Metastasis-Associated Protein 2 Represses NF-Ƙb to Reduce Lung Tumor Growth And

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Author Manuscript Published OnlineFirst on August 14, 2020; DOI: 10.1158/0008-5472.CAN-20-1158 Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited.

1 Metastasis-associated protein 2 represses NF-ƙB to reduce lung tumor growth and

2 inflammation

3 Nefertiti El-Nikhely1#, Annika Karger1, Poonam Sarode1, Indrabahadur Singh1§, Andreas

4 Weigert2, Astrid Wietelmann1, Thorsten Stiewe3, Reinhard Dammann4, Ludger Fink5,

5 Friedrich Grimminger6, Guillermo Barreto1,7, Werner Seeger1,6,8, Soni S. Pullamsetti1,6, Ulf R.

6 Rapp1, Rajkumar Savai1,6,8*

7 Affiliations: 1Max Planck Institute for Heart and Lung Research, Member of the German

8 Center for Lung Research (DZL), Member of the Cardio-Pulmonary Institute (CPI), Bad

9 Nauheim, Germany; 2Institute of Biochemistry I, Goethe University Frankfurt, Frankfurt,

10 Germany; 3Institute of Molecular Oncology, Member of the DZL, Philipps-University

11 Marburg, Marburg, Germany; 4Institute for Genetics; member of the German Center for

12 Lung Research (DZL), Justus-Liebig-University, Giessen, Germany; 5Institute of Pathology and

13 Cytology, UEGP, Wetzlar, Germany; 6Department of Internal Medicine, Member of the DZL,

14 Member of CPI, Justus Liebig University, Giessen, Germany; 7Brain and Lung Epigenetics

15 (BLUE), Glycobiology, Cell Growth and Tissue Repair Research Unit (Gly-CRRET), Université

16 Paris-Est Créteil (UPEC), Créteil, France; 8Institute for Lung Health (ILH), Justus Liebig

17 University, Giessen, Germany; #present address: Department of Biotechnology, Institute of

18 Graduate Studies and Research, Alexandria University, Egypt; §present address: Emmy

19 Noether Research Group Epigenetic Machineries and Cancer, Division of Chronic

20 Inflammation and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany.

21 Running title: MTA2/NuRD complex in lung cancer

22 Keywords: cRaf/Inflammation/ Lung cancer/ MTA2/ NF-ƙB/ NuRD

Downloaded from cancerres.aacrjournals.org on October 2, 2021. © 2020 American Association for Cancer Research. Author Manuscript Published OnlineFirst on August 14, 2020; DOI: 10.1158/0008-5472.CAN-20-1158 Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited.

23 *Correspondence: PD Dr. Rajkumar Savai, Molecular Mechanisms in Lung Cancer,

24 Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung

25 Research, Parkstrasse 1, D-61231 Bad Nauheim, Germany, Tel: +49 6032 705 420; Fax: +49

26 6032 705 471, Email: [email protected]

27 Financial support: R. Savai, S.S. Pullamsetti, W. Seeger and U.R. Rapp supported by the Max

28 Planck Society. R. Savai, S.S. Pullamsetti, T. Stiewe, F. Grimminger, R. Dammann, G. Barreto,

29 W. Seeger and U.R. Rapp supported by the UGMLC and Loewe Program. U.R. Rapp received

30 a grant from German Cancer Aid (Deutsche Krebshilfe; 109081). R. Savai and S.S. Pullamsetti

31 received Von-Behring-Röntgen-Stiftung (projects 66-LV06 and 63-LV01). R. Savai, S.S.

32 Pullamsetti, W. Seeger and F. Grimminger supported by Cardio-Pulmonary Institute (CPI). R.

33 Savai, S.S. Pullamsetti, T. Stiewe, R. Dammann, W. Seeger and F. Grimminger supported by

34 the German Center for Lung Research (DZL). R. Savai and S.S. Pullamsetti supported by the

35 German Research Foundation (DFG) by the CRC1213 (Collaborative Research Center 1213),

36 projects A01 (S.S. Pullamsetti), A05 (S.S. Pullamsetti) A10* (R. Savai). S.S. Pullamsetti

37 received European Research Council (ERC) Consolidator Grant (866051).

38 Author contributions: R.S., U.R.R, W.S. F.G. planned and initiated the project, and

39 supervised the entire project; N.E., S.S.P., I.S., P.S., G.B., R.S. designed experiments and

40 analyzed the data; N.E., A.H.K performed MTA2 cell culture experiments; P.S. and N.E.

41 performed ChIP experiments and Western blots; N.E., R.S., SSP., wrote the manuscript; T.S.,

42 R.D., provided important constructs and reagents; N.E., As. W. performed MRI analysis. An.

43 W. performed FACS analysis. N.E., I.S., G.B. performed cell fractionation experiments and

44 analyzed data.

45 Competing financial interests: The authors declare no competing financial interests.

46 Supplementary data for this article are available at Cancer Research Online 45

47 (http://cancerres.aacrjournals.org/).

48 Abstract

49 Although NF-ƙB is known to play a pivotal role in lung cancer, contributing to tumor growth,

50 microenvironmental changes, and metastasis, the epigenetic regulation of NF-ƙB in tumor

51 context is largely unknown. Here we report that the IKK2/NF-ƙB signaling pathway

52 modulates metastasis-associated protein 2 (MTA2), a component of the nucleosome

53 remodeling and deacetylase complex (NuRD). In triple transgenic mice, downregulation of

54 IKK2 (Sftpc-cRaf-IKK2DN) in cRaf-induced tumors in alveolar epithelial type-II cells restricted

55 tumor formation, whereas activation of IKK2 (Sftpc-cRaf-IKK2CA) supported tumor growth;

56 both effects were accompanied by altered expression of MTA2. Further studies employing

57 genetic inhibition of MTA2 suggested that in primary tumor growth, independent of IKK2,

58 MTA2/NuRD corepressor complex negatively regulates NF-ƙB signaling and tumor growth,

59 while later dissociation of MTA2/NuRD complex from the promoter of NF-ƙB target genes

60 and IKK2-dependent positive regulation of MTA2 leads to activation of NF-ƙB signaling,

61 epithelial mesenchymal transition, and lung tumor metastasis. These findings reveal a

62 previously unrecognized biphasic role of MTA2 in IKK2/NF-ƙB-driven primary-to-metastatic

63 lung tumor progression. Addressing the interaction between MTA2 and NF-ƙB would provide

64 potential targets for intervention of tumor growth and metastasis.

65 Statement of significance

66 Findings strongly suggest a prominent role of MTA2 in primary tumor growth, lung

67 metastasis, and NF-ƙB signaling modulatory functions

70 Introduction

71 Lung cancer is a multifaceted disease in which inflammation plays an important role in

72 tumor progression. Mutation of KRas occurs in 30% lung adenocarcinoma cases. Blasco et al.

73 using KRas+/G12V mice concluded that cRaf expression was found to be essential for

74 mediating KRas signaling and tumor formation. Several subsequent studies revealed a

75 potential role for cRaf in lung development and carcinogenesis (1,2).

76 Previous studies have shown that cRaf activates not only the mitogenic cascade but also NF-

77 ƙB signaling either via an autocrine loop or even more direct through MEKK1 (3). NF-ƙB

78 transcription factor dependent signaling demonstrated as a key player in diverse immune

79 and inflammatory responses and regulates a wide range of genes (4,5), many of which play

80 roles in neoplastic transformation. Indeed, aberrant NF-ƙB expression and activity are

81 observed in many cancers (6). As to the NF-ƙB signaling, in unstimulated cells, the NF-

82 ƙB1/RelA (p50/p65)– heterodimers are sequestered in the cytoplasm by a family of

83 inhibitors called IƙBs (Inhibitor of ƙB). Whereas, upon stimulation, activation of the NF-ƙB is

84 initiated by the signal-induced degradation of IƙB proteins, which occurs primarily via

85 activation of a kinase called the IƙB kinase (IKK). IKK is composed of a heterodimer of the

86 catalytic IKKα and IKKβ (also known as IKK1 and IKK2, respectively) subunits and a regulatory

87 protein NEMO (NF-ƙB essential modulator) or IKKγ (7). Several studies have attempted the

88 use of selective IKK2 inhibitors to modulate NF-ƙB activity since targeting NF-ƙB sensitizes

89 cancer cells to chemotherapy in non-small-cell lung carcinoma (NSCLC) (8) and breast cancer

90 (9). In support of these data, Bay11-7085, a selective IKK2 inhibitor, increases the

91 therapeutic effectiveness of bortezomib, a proteasome inhibitor, for ovarian cancer (10).

92 However, these attempts failed to reach final clinical trials owing to their off-target effects.

93 These studies emphasize the importance of acquiring more insight into the regulation of NF-

94 ƙB. Increasing evidence has shown that NF-ƙB is regulated epigenetically, especially in the

95 context of tumorigenesis. For example, members of NF-ƙB family can, themselves, act as

96 epigenetic regulators of NF-ƙB–dependent gene activation; the homodimer of p50 interacts

97 with HDAC1 to inhibit pro-inflammatory genes (11). This inhibition has also been reported

98 with respect to lipopolysaccharide (LPS) tolerance (12). A study concerning acute myeloid

99 leukemia suggests that C/EBP displaces HDACs from p50 homodimers and thus drives the

100 activation of anti-apoptotic genes (13). Another mechanism for epigenetic regulation is via

101 diverse chromosome regulatory machinery such as the nucleosome and remodelling

102 deacetylase complex (NuRD) complex. The NuRD complex was first discovered in 1998 in

103 different species. NuRD is critical for chromatin assembly, transcription, and genomic

104 stability (14). Its main structural components are metastasis-associated proteins 1/2

105 (MTA1/2), retinoblastoma protein associated protein 46/48 (RbAp46/48); its enzymatic

106 components are chromodomain helicase DNA binding protein 3/4 (CHD3/4) and HDAC1/2. In

107 lung cancer, Liu et al. showed that nuclear MTA2 correlates with lung cancer cell

108 proliferation, tumor size, and lymph node metastasis, making it a potential candidate as a

109 prognostic marker (15). Moreover, MTA2 overexpression was correlated with tumor

110 progression and poor prognosis in a study conducted on patients with esophageal squamous

111 cell carcinoma (16). However, how MTA2/NuRD complex regulates NF-ƙB signaling pathway

112 and how it is contributing to tumorigenesis remains to be elucidated.

113 Hitherto, the epigenetic regulation of NF-ƙB has been an intriguing conundrum. We thus

114 investigated how MTA2, an essential member of the NuRD complex, regulates NF-ƙB and its

115 role in tumorigenesis and the components of the tumor microenvironment.

116

117 Materials & methods

118 Mice and animal experiments

119 The Sftpc-cRaf mouse was originally generated by Ulf Rapp (17). The Tet-O-IKK2CA and Tet-O-

120 IKK2DN mice were obtained from Thomas Wirth (University of Ulm) (18) and Sftpc-rtTA mice

121 were from Jackson Laboratory. Tet-O-IKK2CA and Tet-O-IKK2DN mice were crossed with the

122 Sftpc-rtTA mice to obtain cell-specific expression of modified IKK2 in alveolar type II cells.

123 The double transgenic offspring mice were crossed with Sftpc-cRaf mice to alter IKK2 in

124 adenoma-forming ATII cells. Genotypes were verified by PCR from genomic tail DNA as

125 described previously (19) (Supp. Table 1 for genotyping primers). Transgenes were induced

126 with doxycyclin (500 mg/kg body weight; Ssniff, Soest, Germany) food at the age of 5 weeks

127 and until euthanization.

128 For the syngenic model, C57BL/6 mice were injected subcutaneously with 3 x 106 LLC1 cells,

129 intravenously with 1 x 106 LLC1 cells and tumor growth was monitored for 20-21 days.

130 Tumor volume based on caliper measurements was calculated by the modified ellipsoidal

131 formula (L  W2)/2 as described previously (20,21). For flow cytometry, lung homogenates

132 were digested with collagenase D and DNase for 30 min. After preparing single cell

133 suspension by passing through 100 µm and 40 µm-filters, cells were stained with different

134 antibodies for immune cells (20). All mouse studies were carried out according to the

135 protocols approved by German federal authorities for animal research (Regierungspräsidium

136 Giessen and Darmstadt, Hessen, Germany).

137 Quantitative RT–PCR

138 For isolation of RNA from tissues, 50–100 mg tissue was homogenised in 1 ml Trizol (Qiagen,

139 Germany) twice at 6500 rpm for 25 secs using Precellys® Ceramic Kit 1.4 (PEQLAB, Erlangen,

140 Germany) and Precellys homogenizer. Total RNA isolated from homogenized tumor samples

141 or cell lines was reverse transcribed using the using ImProm-II™ Reverse Transcription

142 System (Promega, Madison, USA) with Oligo-dT primers according to the suppliers’

143 recommendation. Quantitative PCR was carried out in triplicates using iQTM SYBR Green

144 Supermix (Bio-Rad, Germany) according to the manufacturer’s recommendations. Results

145 were analyzed for the relative expression of mRNAs normalized against Hypoxanthine-

146 guanine phosphoribosyltransferase (HPRT) and 18S. A complete list of primers used in the

147 study is shown in Supp. Table 1.

148 Cell culture and activity assays

149 All cell lines were obtained from the American Tissue Collection Center (ATCC) and grown in

150 DMEM (A427, A549, HEK) or RPMI 1640 medium (H2122, H1650, Colo699, LLC1)

151 supplemented with 10% FCS, 100 U/ml penicillin and 100 μg/ml streptomycin at 37 °C with

152 5% CO2. The cell line was authenticated by the manufacturer and checked for mycoplasma,

153 using LookOut® Mycoplasma PCR Detection Kit. The cells were verified to be mycoplasma

154 negative and were used between passages ten to twentyfive. Transduced cell lines were

155 maintained in culture medium containing 6-8 μg/ml puromycin. To stimulate NF-ƙB

156 signaling, cells were treated with TNFα (10 ng/ml) for 1 hr unless otherwise stated. Cells

157 were transiently transfected with different plasmids using Lipofectamine 2000 at a ratio of

158 1:3. The NF-Gluc reporter plasmid for NF-ƙB activity was a kind gift of Bakhos A. Tannous,

159 and experiments using this plasmid were performed as described before (22). Briefly, cells

160 were transfected with NF-Gluc, and after 48 h samples from the supernatant were collected

161 and incubated with 20µM coelenterazine and chemiluminescence was measured. The

162 EpigenaseTM HDAC activity/inhibition direct colorimetric assay kit (Epigentek, USA) was used

163 to determine HDAC activity in nuclear extracts of cells or whole-cell lysates. An amount of

164 10 µg protein was added per well, which are coated with acetylated histone HDAC substrate.

165 The deacetylated products were detected with a specific antibody conjugated with

166 horseradish peroxidase (HRP), the activity of which was measured spectrophotometrically at

167 450 nm.

168 Stable cell generation

169 Stable cells were generated via lentiviral transfection for both MTA2 OE and MTA2 KD. First,

170 HEK293T cells were co-transfected with pLKO-1 empty vector or pLKO-1 carrying shMTA2

171 (for MTA2 KD) or pCDH -CMV-MCS-EF1-copGFP-T2A-Puro empty vector or pCDH-MTA2 (for

172 MTA2 OE) together with the viral packaging vector psPAX2 and envelope vector pMD2G at a

173 ratio of 3:2:1 using TurboFect transfection reagent (Thermo Fisher Scientific Inc., Germany)

174 and serum-free medium. After 48h of transfection, cell medium containing the viral particles

175 was collected to transduce target cells (LLC1 cells with mouse shMTA2 and A549 cells with

176 human shMTA2 and pCDH-MTA2) with the lentiviral vector of interest using polybrene

177 (Fermentas, Germany) at a final concentration of 0.8 μg/ml. Two days later, positive cells

178 were selected with puromycin at a concentration of 6-8 μg/ml according to the cell line.

179 Cell proliferation by BrdU incorporation

180 Cell proliferation was quantified using colorimetric cell proliferation ELISA BrdU kit (Roche,

181 Germany) according to the manufacturer’s protocol. After 24 hrs of serum starvation, the

182 medium was replaced with medium to be tested and incubated for as long as required for

183 the stimulation or inhibition. BrdU was then added to the cells for 2 hrs in a serum-free

184 medium. Cells were then fixed, and BrdU incorporated in proliferating cells was detected

185 with an antibody conjugated with HRP. After the addition of the substrate, the plate was

186 measured at 370 nm with a reference measurement at 492 nm.

187 Invasion assay

188 Invasive ability of the cells was measured using a transwell chamber (Falcon Cell Culture

189 Insert, Corning, Inc) containing membranes with pores of 8 µm, which were initially coated

190 with 100 µl/chamber Matrigel (VWR International). Cells were suspended in serum free

191 medium and 5 x 104 cells/membrane were seeded on top of the Matrigel. DMEM containing

192 10 % FCS was added to the lower compartment as a chemo-attractant. Following incubation

193 at 37 °C in 5 % CO2 for 20 h, the non-invasive cells on the upper side of the membrane were

194 removed using a cotton swab. The invasive cells on the lower surface were fixed in 100 %

195 methanol for 3 min and stained in 10 % crystal violet for 10 min. After a final wash in distilled

196 water, membranes were dried and mounted on slides with pertex. Slides were scanned using

197 a NanoZoomer digital slide scanner C9600 (Hamamatsu Photonics, Japan) and invasive cells

198 were quantified by ImageJ software.

199 Chromatin Immunoprecipitation (ChIP)

200 Chromatin Immunoprecipitation (ChIP) was performed as previously described (23) with

201 slight modifications. Briefly, cells subjected to various treatments were fixed with

202 formaldehyde at a final concentration of 1% for 10 min at room temperature. Glycine was

203 then added at a final concentration of 125mM for 5min to quench formaldehyde.

204 Crosslinked cells were washed three times with cold 1xPBS and collected by scraping. Cell

205 nuclei were separated and sonicated using Bioruptor® Next gen (Diagenode, Belgium) for 16

206 cycles at 90% power. The chromatin solution was collected, diluted with DB-dilution buffer

207 supplemented with protease and phosphatase inhibitors, and then incubated with 80 µl

208 protein A or G agarose beads conjugated with salmon sperm DNA for 1 hrs at 4°C. Aliquots

209 of DNA-protein samples were collected after centrifugation at 1000 xg for 3 min and

210 incubated overnight at 4°C with 2 µg of antibody or IgG in a final volume of 1.8 ml. From the

211 DNA-protein sample, 10-20 % were stored as input control. After incubation agarose beads

212 were added and bound DNA-protein were washed with 800 µl of low salt washing buffer,

213 then high salt washing buffer, then LiCl washing buffer and finally twice with TE buffer. DNA

214 was cross-linked and eluted the DNA with 0.5 µl RNase A (1 mg/ml, Fermentas, Germany) at

215 37°C on thermo-shaker (900 rpm) for 2 hrs followed by 5 µl of 10 mg/ml proteinase K (Sigma

216 Aldrich, Germany) at 56°C for 2 hrs with shaking. Finally, NaCl was added to a final

217 concentration of 0.2 M and incubated overnight at 65°C. Finally, eluted DNA was diluted 1:4

218 with water and used for qPCR. (Primers used for ChIP assay and their sequences and

219 antibodies are listed in Supp. Table 1).

220 Western blotting

221 Lungs or cells were lysed in ice-cold RIPA buffer (50 mM Tris-HCl, pH 8.0, 150 mM NaCl, 0.1%

222 SDS, 0.5% deoxycholate and 1% Nonidet P-40) with protease and phosphatase inhibitor

223 cocktails (Roche) using a homogenizer in a cold environment. After centrifuging for 10 min at

224 full speed at 4°C, the supernatant containing proteins was quantified using the BioRad

225 Protein quantification kit. Protein samples were mixed with 5x SDS sample application buffer

226 and boiled for 3-5 min, and then 20 µg protein was loaded on 10% SDS PAGE gels and

227 transferred to nitrocellulose membranes. After blocking, membranes were incubated with

228 primary antibodies and secondary antibodies. The antibodies used in the study are listed in

229 Supp. Table. 1

230 Immunocytochemistry

231 Cells grown on chamber slides were treated and fixed with acetone-methanol (1:1). After

232 blocking with 5% BSA, cells were incubated with primary antibodies. Indirect

233 immunofluorescence was conducted by incubation with Alexa 488/555–conjugated

234 secondary antibodies (Supp. Table 1). After incubation, slides were counterstained with

235 DAPI (for nuclear staining) and mounted with fluorescent mounting medium (Dako

236 Cytomation). At the end of the procedure, fluorescence images were acquired.

237 Fractionation of nuclear lysate by sucrose gradient

238 H1650 cells were cultured in 10 cm-culture plates, two for each condition. After treatment

239 with and TNFα for 6h, cells were washed twice with PBS and collected by scraping for

240 subsequent centrifugation. Using 2ml of hypotonic lysis buffer complemented with protease

241 and phosphatase inhibitors, cell pellets were lysed by vortexing and incubation on ice for 10-

242 15 min followed by centrifugation. Nuclear fractions were lysed by 450 µl native nuclear lysis

243 buffer. A sucrose gradient was prepared by mixing 2 ml of 5%, 13.75%, 22.5%, 31.25%, and

244 40% of sucrose. Tubes were incubated overnight at 4°C. The nuclear samples were overlayed

245 on top of the sucrose gradient and centrifuged at 37,5000 rpm for 16.5 h min. After

246 centrifugation, the plastic tubes were gently pierced from the bottom to collect 500 µl

247 fractions. The proteins collected were then examined by immunoblotting.

248 Histology, immunofluorescence staining, and immunohistochemistry

249 Mouse lung tissues were collected at different times and fixed with 10% formalin, paraffin-

250 embedded and sectioned for hematoxylin and eosin staining, immunohistochemistry (IHC)

251 and immunofluorescence staining. Antibodies are listed in Supp. Table 1. For

252 immunofluorescence, tissue sections were hydrated and incubated with trypsin for 10 min

253 for antigen retrieval or with citrate for 30 min. Then, tissues were blocked in 5% BSA with

254 0.1% Triton-X in PBS for 1 hr at RT, to avoid unspecific binding of the antibodies. The

255 following primary antibodies were used: RELA, C-Raf, PCNA, MTA2, and IKK2, all diluted

256 1:200. After incubation with the primary antibodies at 4°C overnight, slides were incubated

257 with the corresponding Alexa Fluor®-labelled secondary antibodies (Supp. Table 1) at a

258 dilution of 1:1000, counterstained with 4,6-diamidino-2-phenylindole (DAPI, Life

259 Technologies, USA) and mounted with Dako fluorescent mounting media (Dako, North

260 America, Inc., USA). Quantification of total fluorescent intensity was carried out by

261 computer-aided image analysis using ImageJ software.

262 Statistical analysis

263 Statistical analyses were performed with GraphPad Prism 5 and 6 Software. Student's t-test

264 (two-tailed) was used to compare two groups. When more than two groups were compared,

265 differences among the groups were determined by one-way ANOVA with Tukey’s post test

266 for unpaired non-parametric variables. Data are expressed as mean ± SEM, and statistical

267 significance was set at p ≤ 0.05.

268

269 Results

270 IKK2 is required for NF-ƙB activation and subsequent tumor growth

271 KRAS, which is at the top of the mitogenic cascade, plays an essential role in many cancers.

272 Activation of its downstream target, cRaf, is indispensable for the formation of lung

273 adenomas (24). Hence, we used a mouse model of cRaf to dissect its function and possibly

274 it's regulation. In the Surfactant Protein C (Sftpc)-cRaf mouse model, alveolar type II (ATII)

275 cells grow uncontrollably, leading to the formation of lung adenomas or hyperplasia (Fig.

276 1A). Lung homogenates of Sftpc-cRaf mice exhibited increased expression of genes involved

277 in NF-ƙB signaling (Rela, Nfkb1, Tnf), regulator kinases Ikbka and Ikbkb (IKK1 and IKK2,

278 respectively) as well as the NF-ƙB target genes (Mmp2, Mmp9, Fn1, Ccnd1) suggesting the

279 activation of NF-ƙB (Fig. 1B). These results support that the canonical IKK2-NF-ƙB axis is one

280 of the downstream signaling pathways activated by cRaf, which is thought to be crucial for

281 the activation of KRAS signaling as well (25). To further explore this axis, a triple transgenic

282 mouse model was established to alter the Inhibitor of Nuclear Factor Kappa B Kinase Subunit

283 Beta (IKK2) (constitutive activation, CA, and dominant-negative inhibition, DN) in ATII cells

284 harboring the Sftpc-cRaf transgene (Fig. 1C). Mice with dominant-negative IKK2 (Sftpc-cRaf-

285 IKK2DN) had fewer tumors as quantified by H&E staining image analysis and by magnetic

286 resonance imaging (MRI) whereas IKK2 activation in ATII cells (Sftpc-cRaf-IKK2CA) promoted

287 tumor formation owing to increased cell proliferation as indicated by cRaf and PCNA

288 expression (Fig. 1D, F). In accordance, compliance of the respiratory system (Crs), tissue

289 damping and elastance also improved upon downregulation of IKK2 (Fig. 1E). Furthermore,

290 the effects of IKK2 modulation also caused changes in the lung immune microenvironment.

291 IKK2 downregulation largely suppressed the infiltration of macrophages, T cells, neutrophils,

292 and dendritic cells into the lung, whereas IKK2 activation enhanced the accumulation of

293 these cells (Supp. Fig. 1).

294 MTA2 play a potential role in IKK2 driven lung metastasis

295 As tumorigenesis was markedly inhibited in Sftpc-cRaf-IKK2DN lungs, we next investigated the

296 impact of IKK2 up and downregulation in epithelial cells. The double transgenic mouse lines

297 with altered IKK2 in ATII cells (Sftpc-IKK2CA and Sftpc-IKK2DN) (Supp. Fig. 2A) were

298 subcutaneously injected with LLC1 lung cancer cells. Notably, constitutive activation of IKK2

299 created a favorable niche for LLC1 metastasis to the lung; more metastatic nodules were

300 observed in Sfptc-IKK2CA lungs as compared to WT and Sfptc-IKK2DN lungs (Fig. 2A, B).

301 Further, ATII cells were isolated from Sfptc-IKK2DN lungs and screened for differential

302 expression of major genes known to play a role in cancer using RT2 profiler PCR array. Both

303 NF-ƙB and non-NF-ƙB target genes were regulated in Sfptc-IKK2DN ATII cells as compared to

304 WT ATII cells, which includes both NF-ƙB (e.g., Rela, Nfkb1 and Mmp9) and non-NF-ƙB target

305 genes (e.g., Mta2 and Tek) (Fig. 2C, Supp. Table 2). Additionally, we performed mRNA

306 expression profiling of the above-mentioned genes from laser micro-dissected (LMD) tumors

307 from WT, Sftpc-cRaf, Sftpc-cRaf-IKK2CA, and Sftpc-cRaf-IKK2DN mice. The expression of Mta2,

308 Mmp9, and Tek increased in Sftpc-cRaf and Sftpc-cRaf-IKK2CA as compared to WT, while only

309 Mta2 showed a significant reduction in Sftpc-cRaf-IKK2DN as compared to Sftpc-cRaf-IKK2CA

310 (Fig. 2D, Supp. Fig. 2B). Similar to known NF-ƙB target genes (Rela, Nfkb1, and Mmp9),

311 expression of Mta2 in lung homogenates (Fig. 2E, Supp. Fig. 2C) and immunofluorescence

312 staining in lungs (Fig. 2F) confirmed upregulation of Mta2 in Sftpc-cRaf and Sftpc-cRaf-IKK2CA

313 and downregulation in Sftpc-cRaf-IKK2DN mice. To understand the role of MTA2 in IKK2-

314 driven lung metastasis, LLC1 MTA2 KD cells were generated (Supp. Fig. 2D) and injected in

315 Sfptc-IKK2CA and Sfptc-IKK2DN mice. The injection of LLC1 MTA2 KD cells showed a significant

316 reduction in metastatic tumor nodules in both Sfptc-IKK2CA and Sfptc-IKK2DN mice compared

317 to LLC1 control cells (Fig. 2G, H); indicating that MTA2 plays a potential role in IKK2-driven

318 lung metastasis.

319 Knockdown of MTA2 has an opposite influence on primary and metastatic tumor growth

320 To study the impact of MTA2 on tumor growth, human (A549, H1650) and mouse (LLC1) lung

321 cancer cells with stable overexpression (MTA2 OE) and knockdown (MTA2 KD) of MTA2 were

322 established by transfection with plasmids encoding MTA2 cDNA and lentivirus-mediated

323 short hairpin RNA, respectively. A549 and H1650 MTA2 OE cells increased mRNA expression

324 of MTA2, no effect was observed MTA1 and MTA2 (Fig. 3A, Supp. Fig. 3A, B). Overexpression

325 of MTA2 in A549 decreased their cell growth and proliferation (Fig. 3B) by decreasing

326 proliferation markers at mRNA level (PCNA, MKI67) and protein level (PCNA, pERK, CCNB1,

327 and CCND1) (Fig. 3C, Supp. Fig. 3C). Further overexpression of MTA2 in H2122, H1650, and

328 Colo699 lung cancer cell lines also showed decreased proliferation (Supp. Fig. 3D). On the

329 other hand, MTA2 overexpression increased invasion of cells as compared to controls (Fig.

330 3D) by decreasing epithelial markers (CDH1 and KRT18), while increasing expression of

331 epithelial markers (FN1 and VIM) at mRNA and protein level in both A549 and H1650 cells

332 (Fig. 3E, F, Supp. Fig. 3E-G) obviously suggesting MTA2 involvement in epithelial

333 mesenchymal transition (EMT) processes. Opposite effects of proliferation and EMT

334 phenotype were observed in A549 and H1650 MTA2 KD cells (Fig. 3G–L, Supp. Fig. 3H-L).

335 Similarly, increased proliferation and decreased invasion were observed upon knockdown of

336 MTA2 in mouse lung cancer syngeneic LLC1 cells (Supp. Fig. 3M). These findings support a

337 differential role of MTA2 on primary tumor growth and metastasis in vitro.

338 Further, LLC1 MTA2 KD cells were subcutaneously and intravenously injected into syngeneic

339 C57BL/6 (WT) mice to understand the role of MTA2 in vivo primary and metastatic tumor

340 growth, respectively. Similar to Sfptc-IKK2CA (Fig. 2G, H), intravenous injection of LLC1 MTA2

341 KD cells in WT mice reduced metastatic tumor growth (Fig. 4A, Supp. Fig. 4A).

342 Interestingly, subcutaneous injection of LLC1 MTA2 KD cells showed increased tumor growth

343 compared to LLC1 cells injected to in WT mice (Fig. 4B, Supp. Fig. 4B); suggesting that in the

344 absence of constitutive activation of IKK2, MTA2 restricts primary tumor growth either by

345 alteration in the tumor microenvironment or due to direct effect on tumor cell specific NF-ƙB

346 signaling. The analysis of immune cells by FACS in LLC1 control and LLC1 MTA2 KD

347 subcutaneous tumor revealed that MTA2 KD tumors showed increased infiltration of

348 macrophages, but T cells, neutrophils, and dendritic cells did not show any significant

349 alteration in MTA2 KD tumors compared to control tumors (Supp. Fig. 4C). Interestingly,

350 MTA2 KD tumors showed upregulation of NF-ƙB signaling (Nfkb1, Rela), NF-ƙB target genes

351 (Nfkbia, Mmp9, Tnf) and proliferation genes (Ccnd1, Myc), indicating negative regulation of

352 NF-ƙB signaling by MTA2 (Fig. 4C, D).

353 As evidences suggests that, in the course of tumor progression, increased inflammation and

354 reactive oxygen species (ROS) can regulate NF-ƙB signaling as well as trigger an oxidative

355 stress-induced response, we explored whether increased inflammatory and/or oxidative

356 stress conditions (stimulating with TNFα and H2O2) can explain opposite roles exerted by

357 MTA2 in primary tumor growth and metastasis (26,27). In corroboration, the short

358 stimulation (2 hrs) of A549 cells with two different concentrations of TNFα (10 and 100 ng)

359 and H2O2 (25 and 250 µM) altered the expression of NF-ƙB signaling genes as well as

360 epithelial-mesenchymal markers. A549 cells treated with a higher concentration of TNFα

361 (100 ng) and H2O2 (250 µM) increased the expression of IKK2, RELA, MTA2, NF-ƙB target

362 genes (MMP9, CCND1) and mesenchymal marker (FN1), while decreased the expression of

363 the epithelial marker (CDH1) compared to control cells and A549 cells treated with a low

364 concentration of TNFα and H2O2 (Supp. Fig. 4D). Altogether, these results suggest that, in

365 the progression of IKK2-driven primary to metastatic tumor growth, MTA2 may play a

366 biphasic role in IKK2-NF-ƙB signaling.

367 MTA2 plays a biphasic role in IKK2-NF-ƙB signaling

368 To understand the contribution of MTA2 to IKK2-NF-ƙB signaling, we stimulated A549 cells

369 with TNFα for different time durations. Upon TNFα stimulation, (i) the expression of IKK2

370 and RELA increased starting from 1 hr (Fig. 5A-B), (ii) the expression of MTA2 increased from

371 6 hrs (Fig. 5A-B), and (iii) the expression of NF-ƙB target genes (MMP9, FN1, NFKB1, CCND1)

372 drastically increased from 6 hrs (Fig. 5C, Supp. Fig.5A). Notably, MTA2 was identified as one

373 of the overexpressed genes in the metastatic lungs of Sfptc-cRaf-IKKCA and Sfptc-IKKCA lungs.

374 Therefore, to understand IKK2-mediated MTA2 modulation and vice versa, we performed

375 siRNA-mediated knockdown of IKK2 or MTA2 in unstimulated (0 hr), 1 hr-TNFα stimulated

376 (time point at which expression of IKK2, RELA increased but not the MTA2 and NF-ƙB target

377 genes, 1 hr) and 6 hrs-TNFα stimulated A549 cells (time point at which expression of all the

378 genes are increased, 6 hrs). In si_IKK2 cells as compared to si_NS (control), the expression of

379 IKK2 and RELA was downregulated at all time points of TNFα stimulation, but the expression

380 of MTA2 and the target genes of NF-ƙB (MMP9, CCND1, FN1) were downregulated only after

381 6hr stimulation with TNFα (Fig. 5D-F, Supp. Fig.5B). Wherein, in si_MTA2 cells as compared

382 to si_NS (control), expression NF-ƙB target genes showed an increase in the absence (0 hr)

383 and during short-term (1 hr) stimulation with TNFα and decrease after 6 hrs stimulation with

384 TNFα (Fig. 5G-I, Supp. Fig.5C). Altogether these results suggest that – (i) in the absence (0 hr)

385 and during short-term (1 hr) stimulation with TNFα, MTA2 negatively regulates target genes,

386 without regulating the expression of IKK2, while (ii) during the long-term (6 hrs) stimulation

387 with TNFα, IKK2-RELA-MTA2 axis positively regulates the expression of target genes;

388 indicating that MTA2 plays a biphasic role in IKK2-NF-ƙB activation.

389 Early IKK2-NF-ƙB activation via TNFα led to the release of MTA2/NuRD repressing complex

390 from NF-ƙB target genes

391 As MTA family members, together with the other components of the NuRD complex, are

392 known to interact and modulate the expression of several genes, it was interesting to

393 investigate whether MTA2 binds to NF-ƙB members through the NuRD complex. At first, we

394 compared the response of A549 and H1650 to TNFα, which demonstrated that H1650 shows

395 a more robust NF-ƙB activation compared to A549 (Fig. 6A). Therefore, to obtain more

396 precise results, we performed nuclear fractionation in H1650 cells to assess how the

397 composition of the multi-protein MTA2/NuRD complex and NF-ƙB members are altered by

398 TNFα stimulation. Nuclear fractionation using sucrose gradient identified members of the

399 NuRD complex (HDAC1, HDAC2, CHD4, and RbAp46) and NF-ƙB in the same fractions, and

400 importantly an additional HDAC1 band appears in fractions 7-15 after stimulation with TNFα

401 (Fig. 6B), suggesting an acetylated form of HDAC1. Acetylation of HDAC1, which is known to

402 be inactivating (28), was confirmed in samples treated with TNFα as seen after pull-down

403 with an antibody that recognizes acetylated proteins (Fig. 6C). HDAC1 activity was

404 significantly reduced in cells treated with TNFα (fractions 7–15, Fig. 6D). Moreover, higher

405 NF-ƙB activity was detected in fractions 7–15 after TNFα treatment (blue bars in Fig. 6E). A

406 proximity ligation assay in A549 cells confirmed the direct interaction between MTA2 and

407 RELA. This interaction was stronger upon MTA2 overexpression, whereas MTA2 knockdown

408 abolished the interaction (Fig. 6F). Correspondingly, upon shorter TNFα stimulation to A549

409 cells, stronger MTA2-RELA interaction was observed in nuclei (Fig. 6G).

410 Finally, to determine the dynamics of MTA2 binding at the consensus NF-ƙB binding sites to

411 promoters of NF-ƙB target genes (NFKB1 proximal, NFKB1 upstream, NFKBIA, MMP9,

412 CCND1) during the short- and long- term TNFα stimulation, we performed ChIP at the time

413 points mentioned above (0 hr, 1 hr, 6 hrs). Interestingly, both short- and long- term

414 stimulation with TNFα leads to enrichment of RELA and NFKB1 (Fig. 7A, Supp. Fig.6A) and

415 the release of MTA2 and other members of the NuRD complex, like RbAp46 and HDAC1 from

416 the promoters of target genes (Fig. 7B, Supp. Fig.6B, C), suggesting a positive regulation of

417 IKK2-NF-ƙB signaling by MTA2 occurs in the long term TNFα stimulation. At this point, it is

418 worth mentioning that, in the absence of TNFα stimulation, NF-ƙB reporter activity in A549

419 cells was reduced with MTA2 overexpression, while knockdown of MTA2 increased NF-ƙB

420 reporter activity (Supp. Fig.7A, B).

421 Further, to confirm the causative role of MTA2 in mediating IKK2-NF-ƙB signaling during

422 short- and long- term TNFα stimulation, we performed overexpression or knockdown of

423 MTA2 in the presence of TNFα at different time points mentioned above, followed by ChIP

424 analysis. In A549 MTA2 KD, RELA was enriched at the promoters of NF-ƙB target genes

425 (NFKB1 proximal, NFKB1 upstream, NFKBIA, MMP9, CCND1) only in the absence (0 hr) and

426 during short-term (1 hr) stimulation with TNFα compared to A549 control cells (Supp.

427 Fig.7C). On the contrary, in A549 MTA2 OE, occupancy of RELA was decreased and

428 occupancy of MTA2 was increased at the promoters in the absence (0 hr) and during short-

429 term (1 hr) stimulation with TNFα (Supp. Fig.7D, E). These results confirmed that the positive

430 regulation of IKK2-NF-ƙB signaling by MTA2 occurs only in the long term TNFα stimulation.

431

432 Discussion

433 These findings reveal a previously unrecognized tumor-suppressive role as well as NF-ƙB

434 signaling modulatory function of MTA2. This concept, summarized in the diagram in Fig. 7C,

435 is based on the findings that IKK2 alteration in ATII cells (both, constitutive activation and

436 dominant negative inhibition) in the presence of Sftpc-cRaf-induced tumor burden regulate

437 the lung immune microenvironment and tumor growth; MTA2 was identified as a non- NF-

438 ƙB target gene regulated by IKK2 and MTA2 is regulated according to the level of NF-ƙB

439 activation within cancer cells. Under unstimulated conditions, MTA2 negatively regulates NF-

440 ƙB pathway by forming the MTA2/NuRD corepressor complex and interacting with RelA at

441 the promoters of NF-ƙB target genes, leading to decreased primary tumor growth (panel 1).

442 However, the IKK2 activation mediated by short time exposure to inflammatory or growth

443 factor stimuli, does not regulate the expression of MTA2, but releases the MTA2/NuRD

444 complex from the promoters thereby increasing the expression of NF-ƙB target genes that

445 subsequently promotes primary tumor growth, emphasizing the biphasic role of MTA2 in

446 IKK2-NF-ƙB signaling-mediated lung cancer progression (panel 2). On the other hand, in the

447 presence of long-term exposure to inflammatory or growth factor stimuli, IKK2 not only

448 increases the expression of NF-ƙB target genes, but also the expression of MTA2.

449 Importantly, the upregulation of MTA2 regulates the expression of epithelial and

450 mesenchymal markers, thereby promoting epithelial mesenchymal transition and lung

451 metastasis (panel 3).

452 Inflammation and cancer were linked more than a century ago when Rudolf Virchow

453 identified leukocyte infiltration in neoplastic tissues (29). Many years of research followed

454 until the discovery of NF-ƙB, and this paved the way for more insight into the contribution of

455 inflammatory signaling to cancer development. NF-ƙB is not only involved in innate and

456 adaptive immune responses, but it governs the expression of a wide set of diverse genes

457 regulating neoplastic transformation (30,31). Many tumors, especially solid tumors, exhibit

458 constitutive activation of NF-ƙB canonical signaling pathway. This fact encouraged several

459 researchers to develop NF-ƙB inhibitors and IKK2 inhibitors as an adjunct therapy to existing

460 cancer treatment modalities. However, success is presently modest at best.

461 Our results in transgenic mice where cRaf is activated in epithelial cells (ATII) reveal an

462 upregulation of the NF-ƙB pathway and activation of NF-ƙB pathway via IKK2 is shown to

463 control survival, inflammation as well as proliferation in the context of tumorigenesis. This

464 was observed in several other models; in a mouse model of precancerous pancreatic lesions,

465 Daniluk et al. showed that oncogenic Ras initiates a positive feedback loop of NF-ƙB

466 activation that further pathologically activates Ras (32). Furthermore, increased NF-ƙB

467 activation is well documented in most cancer cell lines, mice, and human tumors (33). In

468 concordance with our results, a study by Xia et al. reported that IKK2 depletion in mouse

469 lungs leads to reduced tumor proliferation mediated by a reduction in Timp-1 expression

470 (34).

471 In addition, we observed changes in MTA2 levels and nuclear translocation, a non-canonical

472 NF-ƙB target gene, upon IKK2 modulation. This is in line with previous studies suggesting

473 that IKK2 not only regulates NF-ƙB but also has NF-ƙB- independent effects. Chariot et al.

474 reported that IKK subunits in an NF-ƙB independent manner could phosphorylate

475 transcription factors such as FOXO3 and p53 (35). As p53 binding sites are present at the

476 promoter region of MTA2, suggesting p53 as a potential pathway regulating MTA2 gene (26).

477 Moreover, p53 regulates miR-146a and miR-34a, the microRNAs that can post-

478 transcriptionally regulates MTA2 (36,37). In addition, our in vitro experiments with H2O2

479 suggest that oxidative stress /inflammatory stimuli lead to upregulation and/or nuclear

480 exclusion of MTA2. Although similar stimuli were shown to stimulate the expression of

481 MTA1 and subsequently the regulation of EMT (38), no underlying mechanisms have been

482 ascribed. Thus, future studies are warranted to dissect the MTA proteins regulation by IKK2.

483 Surprisingly, both in vitro and in vivo data showed that MTA2 exerts opposite functions in

484 lung cancer development as it initially inhibited primary tumor growth but later favored

485 metastasis. There are limited publications showing the effect of silencing of MTA2 on tumor

486 growth, Lu et al. showed that shMTA2 reduced both primary and metastatic tumor growth in

487 a human breast cancer model with MDA-MB231 cells (39). It is worth mentioning that MDA-

488 MB231 cells are highly aggressive and poorly differentiated and are derived from a

489 metastatic site. This divergence between our data and that of Lu et al. might also be

490 attributed to different mouse models that are used (nude mice versus syngeneic mice) and

491 the influence of IKK2-NF-ƙB-MTA2 axis on tumor microenvironment, which is lacking in the

492 nude mouse model used in the study of Lu et al.

493 These contrasting and novel roles of MTA2 in primary tumor growth and lung metastasis can

494 partly explained by sustained inflammatory response at the later phases of tumor growth.

495 Reactive oxygen species (ROS) increase by growth factors or ongoing inflammation as well as

496 oxidative stress-induced response, at the later phases of tumor growth, may result in IKK2

497 mediated upregulation of MTA2 and release of MTA2 from the promoters of NF-ƙB target

498 genes, resulting in increased expression of NF-ƙB signaling associated inflammation and

499 proliferative genes, epithelial-mesenchymal transition and metastasis formation (27).

500 Importantly, we identified MTA2 is a novel regulator of NF-ƙB pathway and as well identified

501 a biphasic role of MTA2 in NF-ƙB pathway modulation: (1) inhibiting the NF-ƙB pathway by

502 forming the MTA2/NuRD corepressor complex at the promoters of NF-ƙB target genes in

503 unstimulated conditions; and (2) a subsequent function as an activator of NF-ƙB pathway by

504 releasing the MTA2/NuRD corepressor complex from the promoters of NF-ƙB target genes in

505 the presence of growth factor or inflammatory stimuli. Notably, stimulation experiments

506 with inflammatory stimuli such as TNFα suggest that the release of MTA2/NuRD corepressor

507 complex is regulated by IKK2 and is dependent on the duration and concentration of the

508 inflammatory stimuli. These findings provide not only new mechanistic and functional links

509 between NF-ƙB and the MTA2/NuRD complex but also establish new essential roles for the

510 components of MTA2/NuRD complex in primary tumor growth. Interestingly, long term

511 stimulation with TNFα via IKK2 upregulates the expression of MTA2 that subsequently leads

512 to EMT and lung metastasis. In accordance, several studies correlated the overexpression of

513 MTA2 with poor prognosis in different cancer types, like lung cancer (40), colorectal cancer

514 (41), and estrogen receptor-negative breast cancer (42). In our model, MTA2 was identified

515 as one of the overexpressed genes in SpC-cRaf lungs. It is noteworthy that in animal mouse

516 models, mutations of both Kras and Tp53 in the lung lead to the formation of aggressive

517 metastatic lesions though Kras mutations alone merely formed adenocarcinomas (43,44)

518 whereas SpC-cRaf mutation leads to the formation of benign adenomas. This suggests that

519 MTA2 overexpression is a later event during tumorigenesis. Along similar lines, previous

520 studies demonstrate that the MTA2/NuRD complex is essential to the mediation of TWIST-

521 controlled cancer cell invasion and metastasis (39,45).

522 In conclusion, our data strongly suggests prominent role of MTA2 in primary tumor growth,

523 lung metastasis and NF-ƙB signaling modulatory functions. Thus, addressing the interaction

524 between MTA2/NuRD complex and NF-ƙB would provide potential targets for intervention

525 of tumor growth and metastasis. As the NuRD complex contains HDAC subunits, HDAC

526 inhibitors may represent one potential therapeutic avenue for targeting the interaction

527 between MTA2/NuRD complex and NF-ƙB. A recent study demonstrated that HDAC

528 inhibitors have a selective preference for different types of HDAC complexes (46), suggesting

529 that targeting specific HDAC complexes may be feasible with enzyme inhibitors. However, it

530 remains unclear whether one could selectively target tumor-promoting activities while

531 sparing tumor-suppressive functions with this class of drugs. The other therapeutic option is

532 to screen for the drugs modulating the activity or interactions of MTA2/NuRD complex and

533 NF-ƙB and may represent a more selective approach.

534

535 Acknowledgments

536 We thank Yanina Knepper, Jeanette Knepper, Marianne Hoeck, Vanessa Golchert, for

537 excellent technical assistance. We thank Prof. Thomas Wirth for providing Tet-O-IKK2DN and

538 Tet-O-IKK2CA mice. We thank Prof. Bakhos A. Tannous for the NF-Gluc Luciferase reporter

539 plasmid for NF-ƙB activity. We thank Siavash Mansouri for the cell growth experimental help.

540

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661

662 Figure Legends

663 Fig. 1: IKK2 strongly promotes tumor formation.

664 (A) Schematic diagram of the transgene for the lung adenoma model Sftpc-cRaf. The

665 corresponding H&E stained lung sections are shown below. Expression of transgenes was

666 induced by doxycycline at age of 6 weeks. Scale bars = 1.25 µm and 250 µm. (B) mRNA

667 expression of NF-ƙB-associated genes (Rela, Nfkb1, Tnf, Mmp2, Mmp9, Fn1, Ccnd1, Ikbka and

668 Ikbkb) in lung homogenates from Sftpc-cRaf (n=6) compared with wild type (WT) lungs (n=5).

669 Data are presented as ΔCt values normalized to 18s RNA, with error bars indicating SEM

670 (***p≤0.001 compared to WT). (C) Schematic diagram of the different transgenic mouse

671 lines, Sftpc-cRaf, Sftpc-cRaf–IKK2CA (constitutive activation of IKK2) and Sftpc-cRaf–IKKDN

672 (dominant negative, inhibition of IKK2). (D) Quantification of the tumor burden in mouse

673 lungs based on H&E staining and quantitative image analysis of tumor given as tumor

674 area/total lung area ratio (left panel, n=3; *p ≤ 0.05, **p ≤ 0.01 compared to Sftpc-cRaf, §§p ≤

675 0.05 compared to Sftpc-cRaf–IKK2CA) and quantification of MRI lung tumor burden

676 micrographs as Normalized lung intensity (right panel, n=4; *p ≤ 0.05 to WT, §p ≤ 0.05

677 compared to Sftpc-cRaf). (E) Lung compliance of WT, Sftpc-cRaf, Sftpc-cRaf–IKK2CA and Sftpc-

DN 678 cRaf–IKK mice measured as Crs (compliance; mL/cmH2O), Ers (tissue elastance;

679 cmH2O/mL) and tissue damping (cmH2O.s/mL) (n=4) (*p ≤ 0.05, **p ≤ 0.01 compared to WT,

680 §§p ≤ 0.01 compared to Sftpc-cRaf). (F) Representative images (left to right) of H&E staining,

681 MRI, and immunofluorescence staining for cRaf and PCNA of mouse lungs of Sftpc-cRaf,

682 Sftpc-cRaf–IKK2CA and Sftpc-cRaf–IKKDN groups. Scale bars = 1.25 µm, 250 µm and 50 µm.

683

684

685 Fig. 2: Role of MTA2 in IKK2-driven lung tumor metastasis

686 (A) Syngeneic subcutaneous tumor model using LLC1 cells injected into Sfptc-IKK2CA and

687 Sfptc-IKK2DNmice. Representative pictures of the lungs with the black circles pointing to

688 metastatic nodules and corresponding H&E stained lung sections. Scale bar = 1 mm. (B)

689 Quantification of macroscopic and microscopic tumor nodules (n=5) (*p ≤ 0.05 compared to

690 WT, §§p ≤ 0.01 compared to Sfptc-IKKCA). (C) PCR microarray for selected genes that play a

691 role in major cancer pathways in isolated ATII cells of double transgenic Sfptc-IKK2DN mice

692 compared to WT. mRNA expression of Mta2 in (D) laser micro-dissected (LMD) tumor tissue

693 (E) lung homogenates from WT, Sftpc-cRaf, Sftpc-cRaf–IKK2CA and Sftpc-cRaf–IKKDN mice

694 (n=3) (****p≤0.0001 compared to WT, §§§p≤0.001, §§§§p≤0.0001 compared to Sftpc-cRaf). (F)

695 Representative immunofluorescence images of lung tumor sections for Mta2 expression in

696 WT, Sftpc-cRaf, Sftpc-cRaf–IKK2CA and Sftpc-cRaf–IKKDN. Scale bar = 50 µm. (G) Syngeneic

697 metastasis tumor model using LLC1 control and LLC1 MTA2 KD cells injected into Sfptc-IKKCA

698 and Sfptc-IKKDN mice. Representative pictures of the lungs with the black circles pointing to

699 metastatic nodules and corresponding H&E stained lung sections. Scale bar = 1 mm. (H)

700 Quantification of macroscopic and microscopic tumor nodules (n=3) (****p≤0.0001

701 compared to Sfptc-IKKCA mice injected with LLC1 control cells, §§p≤0.01 compared to Sfptc-

702 IKKDN mice injected with LLC1 control cells).

703 Fig. 3: MTA2 Overexpression and silencing alters tumor cell proliferation invasion and

704 EMT.

705 (A) mRNA expression of MTA2 in A549 control and A549 MTA2 OE cells (n=3) (****p ≤

706 0.0001 compared to A549 control). (B) Quantification cell growth of A549 control and A549

707 MTA2 OE cells at 24, 48 and 72 hours (n = 4) (*p≤ 0.05, **p≤ 0.01, ****p≤ 0.0001 compared

708 with A549 control at corresponding time point). Quantification of proliferation of A549

709 control and A549 MTA2 OE cells (n=5) (****p≤ 0.0001 compared to control cells). (C) mRNA

710 expression of PCNA and MKI67 in A549 control and A549 MTA2 OE cells (n = 6) (**P < 0.01

711 compared with A549 control). (D) Quantification of invasion of A549 control and A549 MTA2

712 OE cells (n=5) (**p≤ 0.01 compared to control cells). (E) mRNA expression of epithelial

713 markers (CDH1, KRT18) mesenchymal markers (FN1, VIM) in A549 control and A549 MTA2

714 OE cells (n=3) (*p≤ 0.05, **p≤ 0.01, ***p≤ 0.001 compared to A549 control). (F) Western

715 blot analysis of MTA2, epithelial markers (CDH1, KRT18), mesenchymal markers (FN1, VIM),

716 and β-actin (loading control) in A549 control and A549 MTA2 OE cells. (G) mRNA expression

717 of MTA2 in A549 control and A549 MTA2 KD cells (n=3) (**p ≤ 0.01 compared to A549

718 control). (H) Quantification cell growth of A549 control and A549 MTA2 KD cells at 24, 48

719 and 72 hours (n = 4) (****p≤ 0.0001 compared with A549 control at corresponding time

720 point). Quantification of proliferation of A549 control and A549 MTA2 KD cells (n=5) (***p≤

721 0.001 compared to control cells). (I) mRNA expression of PCNA and MKI67 in A549 control

722 and A549 MTA2 KD cells (n = 6) (**P < 0.01, ***P < 0.01 compared with A549 control). (J)

723 Quantification of invasion of A549 control and A549 MTA2 KD cells (n=5) (*p≤ 0.05,

724 compared to control cells). (K) mRNA expression of epithelial markers (CDH1, KRT18)

725 mesenchymal markers (FN1, VIM) in A549 control and A549 MTA2 KD cells (n=3) (**p≤ 0.01,

726 ****p≤ 0.0001 compared to A549 control). (L) Western blot analysis of MTA2, epithelial

727 markers (CDH1, KRT18), mesenchymal markers (FN1, VIM), and β-actin (loading control) in

728 A549 control and A549 MTA2 KD cells.

729 Fig. 4: MTA2 inhibition promotes primary tumor growth and inhibits metastatic tumor

730 growth.

731 (A) Syngeneic metastasis tumor model using LLC1 control and LLC1 MTA2 KD cells injected

732 into WT mice. Representative pictures of the lungs with the black circles pointing to

733 metastatic nodules and corresponding H&E stained lung sections. Quantification of

734 microscopic tumor nodules in WT mice injected with LLC1 MTA2 KD and LLC1 control cells

735 (n=3; Scale bar = 1 mm; *p ≤ 0.05 compared to WT mice injected with LLC1 control cells). (B)

736 Syngeneic subcutaneous tumor model using LLC1 control and LLC1 MTA2 KD cells injected

737 into WT mice. Representative pictures of the subcutaneous tumor. Time-dependent tumor

738 growth LLC1 MTA2 KD versus LLC1 control group from LLC1 MTA2 KD and LLC1 control group

739 (n=8) (*p≤ 0.05, **p≤ 0.01, ***p≤ 0.001, compared to WT mice injected with LLC1 control

740 cells). (C) Immunofluorescence representative pictures of control and MTA2 KD tumors

741 stained for MTA2 and RELA (green=MTA2 and red=RELA; Scale bar = 50 µm). (D) mRNA

742 expression analysis of Nfkb1, Rela, Nfkbia, Tnf, Mmp9, Ccnd1, and Myc from control and

743 MTA2 KD tumors. (n=5) (***p≤ 0.001 compared to LLC1 control tumors).

744 Fig. 5: MTA2 play a differential role in the activation of IKK2-NF-ƙB signaling

745 (A) Western blot analysis of IKK2, RELA, MTA2, and β-actin (as loading control) (B) mRNA

746 expression of IKK2, RELA, MTA2, (C) MMP9, FN1 in A549 cells stimulated with TNFα

747 (10ng/mL) for 0, 0.5, 1, 2, 6, and 24 hrs. (n = 3) (****P < 0.0001 compared with A549 cells

748 stimulated with TNFα (10ng/mL) for 0 hr). (D) Western blot analysis of IKK2, RELA, MTA2,

749 and β-actin (as loading control) (E) mRNA expression of IKK2, RELA, MTA2, (F) MMP9, FN1 in

750 A549 cells stimulated with TNFα (10ng/mL) for 0, 1, 6 hrs followed by transfection with si_NS

751 (Non silencing, control siRNA) and si_IKK2 for 24 hrs (n = 3) (*P < 0.05, **P < 0.01 compared

752 with A549 cells stimulated with TNFα (10ng/mL) for 0 hr and transfected with si_NS for 24

753 hrs. §§§P < 0.001, §§§§P < 0.0001 compared with A549 cells stimulated with TNFα (10ng/mL)

754 for 1 hr and transfected with si_NS for 24 hrs. $$$$P < 0.0001 compared with A549 cells

755 stimulated with TNFα (10ng/mL) for 6 hr and transfected with si_NS for 24 hrs). (G) Western

756 blot analysis of IKK2, RELA, MTA2, and β-actin (as loading control) (H) mRNA expression of

757 IKK2, RELA, MTA2, (I) MMP9, FN1 in A549 cells stimulated with TNFα (10ng/mL) for 0, 1, 6

758 hrs followed by transfection with si_NS (Non silencing, control siRNA) and si_MTA2 for 24

759 hrs (n = 3) (***P < 0.001 compared with A549 cells stimulated with TNFα (10ng/mL) for 0 hr

760 and transfected with si_NS for 24 hrs. §§§§P < 0.0001 compared with A549 cells stimulated

761 with TNFα (10ng/mL) for 1 hr and transfected with si_NS for 24 hrs. $$P < 0.01, $$$P < 0.001,

762 $$$$P < 0.0001 compared with A549 cells stimulated with TNFα (10ng/mL) for 6 hr and

763 transfected with si_NS for 24 hrs).

764 Fig. 6: MTA2/NuRD complex interacts with the NF-ƙB complex.

765 (A) Gaussia luciferase NF-ƙB reporter activity assay in A549 and H1650 cells after stimulation

766 with TNFα. (n = 3) (*P < 0.05, ***P < 0.001 compared with control). (B) Fractionation images

767 of H1650 cell nuclear lysates treated with TNFα for 6 h, NF-ƙB complex members (RELA and

768 NFKB1) and NuRD complex members (MTA2, HDAC1, HDAC2, CHD4 and RbAp46) were

769 shown in the various cell fractions in response to TNFα, shown for various cell fractions. (C)

770 Immunoprecipitation of acetylated proteins using anti-acetyl lysine (-AcK) or IgG antibodies

771 showed acetylated HDAC1 after treatment with TNFα; various cell fractions given. (D) HDAC

772 activity was measured in cell fractions 7, 9, 11, 13 and 15 (n = 3) (***P < 0.001 compared

773 with control). (E) NF-ƙB activity assay in response to TNFα, shown for various cell fractions (n

774 = 3) (***P < 0.001 compared with control). Proximity ligation assay in (F) A549 control, A549

775 MTA2 OE, A549 MTA2 KD cells (G) in A549 treated with TNFα (n=3; Scale bar = 50 µm).

776 Fig. 7: MTA2 interacts with NF-ƙB complex at promoter sites of NF-ƙB target genes.

777 Real-time PCR with ChIP assays performed on A549 cells stimulated with TNFα (10ng/mL) for

778 0, 1, 6 hrs. Specific oligonucleotides for consensus NF-ƙB binding sites (NFKB1 proximal,

779 NFKB1 upstream) and target genes (NFKBIA, MMP9, CCND1) used to detect binding in

780 chromatin enriched with (A) Ab_RELA (B) Ab_MTA2 (n = 3) (*P < 0.05, **P < 0.01, ***P <

781 0.001, ****P < 0.0001 compared with Ab_RELA/ Ab_MTA2 stimulated with TNFα (10ng/mL)

782 for 0 hr. §P < 0.05, §§P < 0.01, §§§P < 0.001, §§§§P < 0.0001 compared with Ab_RELA in A549

783 cells stimulated with TNFα (10ng/mL) for 1 hr). (C) Schematic diagram is based on the

784 findings that IKK2 alteration in ATII cells (both, constitutive activation and dominant negative

785 inhibition) in the presence of Sftpc-cRaf-induced tumor burden regulate the lung immune

786 microenvironment and tumor growth; MTA2 was identified as a non- NF-ƙB target gene

787 regulated by IKK2 and MTA2 is regulated according to the level of NF-ƙB activation within

788 cancer cells; Under unstimulated conditions, MTA2 negatively regulates NF-ƙB pathway by

789 forming the MTA2/NuRD corepressor complex and interacting with RelA at the promoters of

790 NF-ƙB target genes, leading to decreased primary tumor growth (panel 1). However, the IKK2

791 activation mediated by short time exposure to inflammatory or growth factor stimuli, does

792 not regulate the expression of MTA2, but releases the MTA2/NuRD complex from the

793 promoters thereby increasing the expression of NF-ƙB target genes that subsequently

794 promotes primary tumor growth, emphasizing the biphasic role of MTA2 in IKK2-NF-ƙB

795 signaling-mediated lung cancer progression (panel 2). On the other hand, in the presence of

796 long-term exposure to inflammatory or growth factor stimuli, IKK2 not only increases the

797 expression of NF-ƙB target genes, but also the expression the MTA2. Importantly, the

798 upregulation of MTA2 regulates the expression of epithelial and mesenchymal markers,

799 thereby promoting epithelial mesenchymal transition and lung metastasis (panel 3).

Metastasis-associated protein 2 represses NF-?B to reduce lung tumor growth and inflammation

Nefertiti El-Nikhely, Annika Karger, Poonam Sarode, et al.

Cancer Res Published OnlineFirst August 14, 2020.

Updated version Access the most recent version of this article at: doi:10.1158/0008-5472.CAN-20-1158

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