Targeting NRAS-Mutant Cancers with the Selective STK19 Kinase
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Published OnlineFirst March 10, 2020; DOI: 10.1158/1078-0432.CCR-19-2604 CLINICAL CANCER RESEARCH | TRANSLATIONAL CANCER MECHANISMS AND THERAPY Targeting NRAS-Mutant Cancers with the Selective STK19 Kinase Inhibitor Chelidonine A C Ling Qian1,2, Kun Chen1,2, Changhong Wang3, Zhen Chen1,2, Zhiqiang Meng1,2, and Peng Wang1,2 ABSTRACT ◥ Purpose: Oncogenic mutations in NRAS promote tumori- cell extracts. The antitumor potency of chelidonine was investi- genesis. Although novel anti-NRAS inhibitors are urgently gated in vitro and in vivo using a panel of NRAS-mutant and needed for the treatment of cancer, the protein is generally NRAS wild-type cancer cells. considered “undruggable” and no effective therapies have yet Results: Chelidonine was identified as a potent and selective reached the clinic. STK19 kinase was recently reported to be a inhibitor of STK19 kinase activity. In vitro, chelidonine treatment novel activator of NRAS and a potential therapeutic target for inhibited NRAS signaling, leading to reduced cell proliferation NRAS-mutant melanomas. Here, we describe a new pharma- and induction of apoptosis in a panel of NRAS-mutant cancer cologic inhibitor of STK19 kinase for the treatment of NRAS- cell lines, including melanoma, liver, lung, and gastric cancer. mutant cancers. In vivo, chelidonine suppressed the growth of NRAS-driven Experimental Design: The STK19 kinase inhibitor was iden- tumor cells in nude mice while exhibiting minimal toxicity. tified from a natural compound library using a luminescent Conclusions: Chelidonine suppresses NRAS-mutant cancer phosphorylation assay as the primary screen followed by verifi- cell growth and could have utility as a new treatment for such cation with an in vitro kinase assay and immunoblotting of treated malignancies. Introduction patients with NRAS-mutant melanoma in a phase III trial; however, binimetinib is still in clinical development (14, 15). The RAS family of small GTPases (HRAS, NRAS, and KRAS) are Recent work demonstrated that the functionally uncharacterized binary molecular switches that transition between an active GTP- serine/threonine kinase STK19 is a novel activator of NRAS (16, 17). bound state and an inactive GDP-bound state (1–4). Stimulation of STK19 phosphorylates NRAS at the evolutionarily conserved residue many cell surface receptors activates membrane-bound RAS proteins serine 89 (S89), which enhances binding between NRAS and its and its downstream signaling pathways, including RAF–MEK–ERK effector proteins, activates downstream signaling pathways, and and PI3K–AKT, which culminate in the promotion of cell growth induces malignant transformation of melanocytes (17). Crossing of and suppression of cell death (5, 6). Aberrant RAS activity due to NRAS Q61R transgenic mice with mice harboring melanocyte-specific oncogenic mutations is frequently associated with the promotion of expression of STK19 or the gain-of-function mutant STK19 D89N tumorigenesis (7, 8); indeed, RAS mutations are present in 20%–30% enhances melanoma formation, confirming the ability of STK19 to of all human cancers (8, 9). Melanoma is characterized by gain-of- stimulate NRAS signaling (17, 18). These observations suggest that function hotspot mutations in NRAS at glutamate 61 (Q61; refs. 10, 11), selective STK19 inhibitors could provide urgently needed therapeutic including arginine, lysine, and leucine mutations (Q61R, Q61K, options to suppress the growth of NRAS-mutant tumors. and Q61L), which are present in approximately 30% of melanomas. Chelidonine is one of the most abundant bioactive isoquinoline These mutations result in a constitutively GTP-bound active confor- alkaloids in extracts of the plant Chelidonium majus, which is also mation of NRAS that drives the malignant transformation of known as the greater celandine (Papaveraceae) and is widely distrib- melanocytes (10–13). However, pharmacologic targeting of mutant uted throughout Europe and Asia (19). Crude extracts of Chelidonium NRAS proteins and the downstream signaling pathways has been majus and purified chelidonine have both been shown to possess challenging. Some drugs with the potential to treat NRAS-mutant antitumor properties, including inhibition of cell proliferation, poten- cancers have been developed, such as the MEK inhibitor binimetinib, tiation of apoptosis, and suppression of cell migration and invasion, in which showed some improvement in progression-free survival of cell lines from such diverse cancers as uveal melanoma, head and neck cancer, gastric carcinoma, liver cancer, and breast cancer (20–24). For 1 example, chelidonine potentiates apoptosis in the HCT116 (KRAS Department of Integrative Oncology, Fudan University Shanghai Cancer Center, k Shanghai, China. 2Department of Oncology, Shanghai Medical College, Fudan G13D) human colon cancer cell line by inhibiting the NF- B signaling University, Shanghai, China. 3Institute of Chinese Materia Medica, Shanghai pathway (25), and it suppresses the migration and invasion of MDA- University of Traditional Chinese Medicine, Shanghai, China. MB-231 (KRAS G13D) human breast cancer cells by inhibiting – –a Note: Supplementary data for this article are available at Clinical Cancer formation of the integrin-linked kinase PINCH -parvin com- Research Online (http://clincancerres.aacrjournals.org/). plex (26). However, the precise mechanisms of action of chelidonine L. Qian and K. Chen contributed equally to this article. and its direct targets in cancer cells remain unclear, greatly hindering its translation to the clinic. Corresponding Author: Peng Wang, Fudan University Shanghai Cancer Center, In this study, we screened a natural compound library using a 270 Dong An Road, Shanghai 200032, China. Phone: 8621-6417-5590; Fax: 8621- – fi 6443-7657; E-mail: [email protected] phosphorylation assay based approach and identi ed chelidonine as a potent and selective inhibitor of STK19. Using biochemical and Clin Cancer Res 2020;26:3408–19 cellular assays, we show that chelidonine is an ATP-competitive doi: 10.1158/1078-0432.CCR-19-2604 inhibitor of STK19 activity and blocks proliferation and induces Ó2020 American Association for Cancer Research. apoptosis in a panel of NRAS-mutant cancer cell lines via inhibition AACRJournals.org | 3408 Downloaded from clincancerres.aacrjournals.org on September 23, 2021. © 2020 American Association for Cancer Research. Published OnlineFirst March 10, 2020; DOI: 10.1158/1078-0432.CCR-19-2604 Chelidonine for NRAS-Mutant Cancer Treatment irradiated diet and sterilized water. The mice were monitored daily for Translational Relevance signs related to their health status and distress. Oncogenic mutations in NRAS promote tumorigenesis, and For toxicity profiling of chelidonine, C57BL/6J mice were injected novel anti-NRAS inhibitors are urgently needed for cancer treat- intraperitoneally with vehicle [normal saline containing 5% (w/v) ment. STK19 kinase was recently identified as a novel activator of Kolliphor HS 15; Sigma] or chelidonine (10 or 20 mg/kg in vehicle) NRAS and a potential therapeutic target for NRAS-mutant mel- once daily and body weights were measured daily. After 21 days, the anomas. In this study, we identified chelidonine, a natural com- mice were euthanized, and blood and organs were collected. Serum pound, as a potent and selective inhibitor of STK19 kinase activity. aspartate and alanine aminotransferase (AST and ALT) activity was Chelidonine effectively inhibited proliferation and induced apo- measured using Assay Kits (Abcam) according to the manufacturer's ptosis in a panel of cancer cells harboring NRAS mutations. instructions. The organs were processed by fixing in 4% paraformal- Chelidonine also suppressed NRAS-driven tumor growth in a dehyde and embedding in paraffin using standard protocols. Tissues mouse model while displaying minimal toxicity. These data indi- were cut into 5-mm thick sections, stained with hematoxylin and eosin cate that chelidonine can suppress the growth of NRAS-mutant (H&E), and observed by light microscopy. cancer cells and could represent a novel option for the treatment of The pharmacokinetic profile of chelidonine was analyzed in mice such malignancies. injected intraperitoneally with chelidonine at 10 mg/kg. Chelidonine concentrations in mouse plasma were measured using an ultra-high performance LC/MS-MS (UHPLC/MS-MS) method established for this study. of pathways downstream of NRAS, including RAF–MEK–ERK and In vivo xenograft experiments were performed as described previ- PI3K–AKT. Similarly, chelidonine impaired cancer cell growth in vivo ously (27). Briefly, 2  106 SK-MEL-2 (NRAS Q61R), WM1366 while having minimal toxicity. Our results suggest that pharmacologic (NRAS Q61L), or SK-MEL-28 (NRAS-WT) cells were mixed with inhibition of STK19 by chelidonine may provide a novel option for Matrigel (1:1) and injected subcutaneously into the left flanks of targeting NRAS-mutant cancers. 8-week-old female nude mice. Tumor size was measured every 3 days with calipers, and tumor volumes were calculated using the following formula: length  width2  0.5. When the tumor volume reached Materials and Methods approximately 200 mm3, mice were injected with vehicle or chelido- Cell lines nine (10 or 20 mg/kg, i.p.) once daily. On the indicated days, the mice SK-MEL-2, SK-MEL-28, SK-MEL-31, HepG2, Hep3B, NCI-H446, were euthanized, and melanoma xenografts were excised, weighed, and SW-1271, HCT116, and MDA-MB-231 cell lines were purchased from processed for further analysis. ATCC; WM2032, WM3406, and WM1366