ANTICANCER RESEARCH 34: 69-80 (2014) NOTCH4 Is a Potential Therapeutic Target for Triple-negative Breast Cancer IORI NAGAMATSU1, HIDEYA ONISHI1, SHOJIRO MATSUSHITA1, MAKOTO KUBO2, MASAYA KAI1, AKIRA IMAIZUMI3, KENJI NAKANO4, MASAMI HATTORI5, YOSHINAO ODA5, MASAO TANAKA2 and MITSUO KATANO1 Departments of 1Cancer Therapy and Research, 2Surgery and Oncology, and 5Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; 3Shukoukai Inc., Tokyo, Japan; 4Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka, Japan Abstract. Background/Aim: The prognosis for triple- receptor (ER)-negative/progesterone receptor (PR)-negative/ negative breast cancer (TNBC) is poor. In the present study, human epidermal growth factor receptor-2 (HER2)-positive we evaluated whether NOTCH4 receptor is a potential new and normal-like subtypes (2). One reason for the poor therapeutic target for TNBC. Materials and Methods: In prognosis of TNBC may be the lack of therapeutic targets vitro proliferation and invasiveness were evaluated in TNBC such as ER, PR and HER2 when chemoresistance arises, cells with or without small-interfering RNA (siRNA) for although the chemotherapy response rate is relatively high. NOTCH4, and with or without NOTCH4 plasmid Consequently, development of an effective therapeutic transfection. In vivo, MDA-MB-231 cells with or without strategy for TNBC is urgently required. NOTCH4 siRNA were subcutaneously implanted into the Morphogenesis signaling is thought to have potential for the flank regions of mice. The frequency of nuclear translocation identification of therapeutic targets for cancer. Previously, we of NOTCH4 was assessed by immunohistochemistry in 21 demonstrated that the hedgehog signaling pathway, which is TNBC samples and 46 non-TNBC samples. Results: a morphogenesis signaling pathway, is activated in various NOTCH4 inhibition in TNBC cells reduced proliferation and types of cancer (3, 4), and that it contributes to the invasiveness, and NOTCH4 overexpression in TNBC cells proliferation, invasiveness, and progression of cancer (5-8). increased proliferation and invasiveness. NOTCH4 inhibition In addition, pharmacological manipulation of NOTCH reduced tumour volume and tumourigenicity of mouse signaling, another morphogenesis signaling pathway, might xenografts. TNBC cells had a higher frequency of nuclear be a new strategy for human cancer treatment (9). For translocation of NOTCH4 than other cells. Conclusion: example, a phase I clinical trial using the γ-secretase NOTCH4 is a new potential therapeutic target for triple- inhibitor, MK-0752, which inhibits NOTCH signalling, has negative breast cancer. been started for adult patients with advanced solid tumours (10). We also reported that a γ-secretase inhibitor, N-[N-(3, Breast cancer continues to be a leading cause of cancer- 5-difluorophenacetyl-L-alanyl)]-S-phenylglycine-t-butyl related death among women worldwide (1), even though it ester, has a synergic anti-tumour effect with paclitaxel or is a cancer for which many standardized adjuvant therapies docetaxel (11). NOTCH signaling is mediated by five are available. Of the different types of breast cancer, triple- ligands: DELTA-like 1, DELTA-like 3, DELTA-like 4, negative breast cancer (TNBC) accounts for 15% of all JAGGED-1, and JAGGED-2, and -4 receptors: NOTCH-1 to breast cancers and has the worst prognosis compared to other -4 (12-14); and cell-to-cell contact is essential for the breast cancer subtypes: luminal-A, luminal-B, estrogen activation of NOTCH signalling (15). Many studies have reported the roles of NOTCH1 and NOTCH3 in breast cancer. NOTCH1 contributes to the migration and invasion of breast cancer (9), and high expression of NOTCH1 and its Correspondence to: Hideya Onishi, Cancer Therapy and Research, ligand confers a poor prognosis (16-18). Others Graduate School of Medical Sciences, Kyushu University, 3-1-1 demonstrated that HER2-negative breast cancer is correlated Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. Tel: +81 926426220, with the expression of both NOTCH1 and NOTCH3 (19), Fax: +81 926426221, e-mail: [email protected] and that overexpression of activated NOTCH1 and NOTCH3 Key Words: Triple-negative breast cancer, NOTCH4, invasion, blocks mammary development but induces tumourigenesis of proliferation, therapeutic target, breast cancer. the breast (20). Only a few reports have been published 0250-7005/2014 $2.00+.40 69 ANTICANCER RESEARCH 34: 69-80 (2014) regarding the role of NOTCH4 in breast cancer, but it is Kyushu University (24-222). Paraffin sections of breast cancer known that the activated forms of NOTCH1 and NOTCH4 tissues were deparaffinized and rehydrated according to routine are present in human breast cancer (21), and that NOTCH4 procedures. The sections were immersed in 3% H2O2 and 10% goat serum and incubated with primary antibody against NOTCH4 (sc- receptor signalling is involved in the regulation of breast 5594, 1:100; Santa Cruz Biotechnology, CA, USA) at 4˚C cancer stem cell activity (22). However, the function of overnight. The samples were incubated with HISTFINE simple stain NOTCH4 in breast cancer remains poorly-understood. MAX-PO(R) (Nichirei, Tokyo, Japan) and visualized using 3,3’- In the present study, we analyzed the biological diaminobenzidine with haematoxylin counterstaining. significance of the NOTCH4 receptor in TNBC to evaluate whether the NOTCH4 receptor is a potential therapeutic Western blot analysis. Protein samples were extracted using M-PER target for TNBC. (Thermo Fisher Scientific, Chicago, IL, USA), lysed in sodium dodecyl sulphate (SDS) buffer, separated by SDS-polyacrylamide gel Materials and Methods electrophoresis(PAGE), and transferred to PVDF membranes. The membranes were incubated with primary antibodies against NOTCH4 (sc-8645, 1:200; Santa Cruz Biotechnology) or α-tubulin (1:1000; Cell lines. TNBC cell lines (MDA-MB-231 and Hs578T) and non- Sigma-Aldrich, St. Louis, MO, USA) at 4˚C overnight, followed by TNBC cell lines (MCF-7 and BT-474) were obtained from the peroxidase-labelled secondary antibodies at 37˚C for 1 h. Immunoblots American Type Culture Collection (Manassas, VA, USA). MDA- were developed using the ECL Prime Western Blotting Detection MB-231, MCF-7, and BT-474 cells were maintained in RPMI-1640 System (GE Healthcare Life Sciences, Buckinghamshire, UK). (Nacalai Tesque, Kyoto, Japan) supplemented with 10% foetal bovine serum (FBS; Biological Industries, Kibbutz Beit Haemek, Proliferation assay. Cells (5×103 cells/well) were seeded in 96-well Israel) at 37˚C in 5% CO . Hs578T cells were maintained in 2 plates in complete culture medium. After 24, 48, and 72 h, cell Dulbecco’s modified Eagle’s medium (DMEM; Nacalai Tesque) growth was determined using Cell Count Reagent SF (Nacalai supplemented with 10% FBS at 37˚C in 5% CO . 2 Tesque). RNA interference. SiRNAs for NOTCH1 (ON-TARGETplus SMART pool L-007771), NOTCH2 (ON-TARGETplus SMART pool L- Soft agar colony-formation assay. Cells were mixed with RPMI- 012235), NOTCH3 (ON-TARGETplus SMART pool L-011093), 1640 containing 0.3% agar and 10% FBS and plated on 0.3% basal NOTCH4 #1 (ON-TARGETplus SMART pool L-111108), and agar in six-well plates. Each well was then further covered with negative control siRNA were obtained from Dharmacon RNA RPMI-1640 containing 10% FBS. Three weeks later, the colonies Technologies (Chicago, IL, USA). The siRNA for NOTCH4 #2 (sc- were stained with crystal violet (Sigma-Aldrich). 40137) was obtained from Santa Cruz Biotechnology (Dallas, TX, USA). Cells were transfected with 25 nM siRNA using the Cell invasion assay. The invasiveness of breast cancer cells was Lipofectamine RNAiMAX Reagent (Invitrogen, Carlsbad, CA, USA) assessed based on the invasion of cells through Matrigel-coated according to the manufacturer’s protocol. At 48 h after transfection, transwell inserts as previously described (8). In brief, the upper the cells were harvested and subjected to further analyses. surface of a filter (pore size, 8.0 μm; BD Biosciences, Heidelberg, Germany) was coated with basement membrane Matrigel (BD Plasmids and cell transfection. The pNOTCH4 plasmid was Biosciences). Cells were suspended in RPMI-1640 then 1.0×105 cells obtained from Promega (Madison, WI, USA) and transfected with were added to the upper chamber and incubated for 4 h. After Lipofectamine 2000 (Invitrogen) according to the manufacturer’s incubation, the filter was fixed and stained with Diff-Quick reagent protocol. At 24 h after transfection, the cells were harvested and (International Reagents, Kobe, Japan). All cells that had migrated subjected to further analyses. from the upper to the lower side of the filter were measured using a BIOREVO BZ-9000 microscope (Keyence, Osaka, Japan). Tumour Conventional and real-time reverse transcription polymerase chain cell invasiveness testing was carried out in triplicate wells. reaction (RT-PCR). Total RNA was isolated using the High Pure Isolation Kit (Roche Diagnostics Gmbh, Mannheim, Germany) and In vivo xenograft tumour model. Five-week-old female severe reverse-transcribed using the Quantitect Reverse Transcription Kit combined immunodeficiency (SCID) mice were purchased from (Qiagen, Hilden, Germany), according to the manufacturers’ Charles River Laboratories Japan (Kanagawa, Japan) and protocols. Conventional and real-time RT-PCR reactions were acclimatized for two weeks. All animal procedures were approved performed using the sets of primers shown in Table I with