Melatonin synergizes BRAF-targeting agent vemurafenib in melanoma treatment by inhibiting iNOS/hTERT signaling and cancer-stem cell traits

• Published in: Journal of experimental & clinical cancer research 2019-02, Vol.38 (1), p.48-15, Article 48
• Main Authors: Hao, Jiaojiao, Fan, Wenhua, Li, Yizhuo, Tang, Ranran, Tian, Chunfang, Yang, Qian, Zhu, Tianhua, Diao, Chaoliang, Hu, Sheng, Chen, Manyu, Guo, Ping, Long, Qian, Zhang, Changlin, Qin, Ge, Yu, Wendan, Chen, Miao, Li, Liren, Qin, Lijun, Wang, Jingshu, Zhang, Xiuping, Ren, Yandong, Zhou, Penghui, Zou, Lijuan, Jiang, Kui, Guo, Wei, Deng, Wuguo
• Format: Article
• Language: English
• Subjects: Analysis; Animals; Antineoplastic Agents - pharmacology; Antineoplastic Agents - therapeutic use; Antineoplastic Combined Chemotherapy Protocols - pharmacology; Antineoplastic Combined Chemotherapy Protocols - therapeutic use; Antioxidants - pharmacology; Antioxidants - therapeutic use; Apoptosis; Apoptosis - drug effects; Brain cancer; Cancer; Cancer stem cell; Cancer therapies; Care and treatment; Cell cycle; Cell Cycle Checkpoints - drug effects; Cell division; Cell growth; Cell Line, Tumor; Drug resistance; Drug Synergism; Endocrine system; Epithelial-Mesenchymal Transition - drug effects; Gene expression; hTERT; Humans; Immunotherapy; iNOS; Kinases; Liver cancer; Luciferase; Male; Melanoma; Melanoma - drug therapy; Melatonin; Melatonin - pharmacology; Melatonin - therapeutic use; Metastasis; Mice; Mice, Nude; Mutation; Neoplastic Stem Cells - drug effects; NF-kappa B - metabolism; NF-κB; Nitric oxide; Nitric Oxide Synthase Type II - antagonists & inhibitors; Physiology; Protein Kinase Inhibitors - pharmacology; Protein Kinase Inhibitors - therapeutic use; Proto-Oncogene Proteins B-raf - antagonists & inhibitors; Signal Transduction - drug effects; Skin Neoplasms - drug therapy; Stem cells; Telomerase - antagonists & inhibitors; Vemurafenib; Vemurafenib - pharmacology; Vemurafenib - therapeutic use; Xenograft Model Antitumor Assays
• ISSN: 1756-9966; 0392-9078; 1756-9966
• DOI: 10.1186/s13046-019-1036-z

As the selective inhibitor of BRAF kinase, vemurafenib exhibits effective antitumor activities in patients with V600 BRAF mutant melanomas. However, acquired drug resistance invariably develops after its initial treatment. Immunohistochemical staining was performed to detect the expression of iNOS and hTERT, p-p65, Epcam, CD44, PCNA in mice with melanoma xenografts. The proliferation and migration of melanoma cells were detected by MTT, tumorsphere culture, cell cycle, cell apoptosis, AO/EB assay and colony formation, transwell assay and scratch assay in vitro, and tumor growth differences were observed in xenograft nude mice. Changes in the expression of key molecules in the iNOS/hTERT signaling pathways were detected by western blot. Nucleus-cytoplasm separation, and immunofluorescence analyses were conducted to explore the location of p50/p65 in melanoma cell lines. Flow cytometry assay were performed to determine the expression of CD44. Pull down assay and ChIP assay were performed to detect the binding ability of p65 at iNOS and hTERT promoters. Additionally, hTERT promoter-driven luciferase plasmids were transfected in to melanoma cells with indicated treatment to determine luciferase activity of hTERT. Melatonin significantly and synergistically enhanced vemurafenib-mediated inhibitions of proliferation, colony formation, migration and invasion and promoted vemurafenib-induced apoptosis, cell cycle arresting and stemness weakening in melanoma cells. Further mechanism study revealed that melatonin enhanced the antitumor effect of vemurafenib by abrogating nucleus translocation of NF-κB p50/p65 and their binding at iNOS and hTERT promoters, thereby suppressing the expression of iNOS and hTERT. The elevated anti-tumor capacity of vemurafenib upon co-treatment with melatonin was also evaluated and confirmed in mice with melanoma xenografts. Collectively, our results demonstrate melatonin synergizes the antitumor effect of vemurafenib in human melanoma by inhibiting cell proliferation and cancer-stem cell traits via targeting NF-κB/iNOS/hTERT signaling pathway, and suggest the potential of melatonin in antagonizing the toxicity of vemurafenib and augmenting its sensitivities in melanoma treatment.