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

Abstract

Background: 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.Methods: 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. Results: 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 cotreatment with melatonin was also evaluated and confirmed in mice with melanoma xenografts.

Melatonin alleviated the immune response and improved the salivary gland function in primary Sjögren’s syndrome

“…In ammatory signalling pathways are closely related to the pathological changes of various chronic diseases in vivo [16,17]. The proin ammatory cytokines produced by the activation of signalling pathways promote the activation of T cells, which plays an important role in the progression of various autoimmune diseases, including pSS [18,19]. Conversely, in ammatory mediators also interfere with the expression of clock genes [20], but the relevant mechanisms involved are complex and have not been fully elucidated yet.…”

“…As indicated in our study, the disordered expression of clock genes observed in pSS patients and animals may be the cause of pSS, or excessive in ammatory responses may disturb the normal expression of biological clock genes. Melatonin can inhibit a variety of important in ammation-related pathways and molecules and may reduce in ammation by blocking these in ammatory signalling pathways, which are closely related to the progression of pSS [9,19,[28][29][30]. Moreover, as a broad antioxidant, melatonin can effectively reduce tissue damage during chronic in ammation [8,9,31].…”

Melatonin synergizes BRAF‐targeting agent dabrafenib for the treatment of anaplastic thyroid cancer by inhibiting AKT/hTERT signalling

“…In recent years, increasing evidence has demonstrated that melatonin has anti‐tumour effect in various cancers, such as melanoma, breast cancer, lung carcinoma and thyroid cancer 24‐27 . Melatonin has been shown to be an effective combination therapy for cancers by improving the curative effect of conventional anticancer drugs, reducing their side effects and overcoming their resistance to chemotherapy 28,29 . However, the combination of melatonin and BRAF‐targeting agent dabrafenib for the treatment of anaplastic thyroid cancer has not been reported.…”

“…[24][25][26][27] Melatonin has been shown to be an effective combination therapy for cancers by improving the curative effect of conventional anticancer drugs, reducing their side effects and overcoming their resistance to chemotherapy. 28,29 However, the combination of melatonin and BRAF-targeting agent dabrafenib for the treatment of anaplastic thyroid cancer has not been reported.…”

Can melatonin and its metabolites boost the efficacy of targeted therapy in patients with advanced melanoma?

“…By means of modulation of OXPHOS, melatonin may finally enhance the mitochondria-mediated proapoptotic effect of BRAF/MEK inhibitors. [39][40][41] Moreover, altered melanin synthesis induced by melatonin may lead to changes in cell plasticity and thus invasiveness.…”