Nicotinamide inhibits melanoma in vitro and in vivo

Abstract

Background Even though new therapies are available against melanoma, novel approaches are needed to overcome resistance and high-toxicity issues. In the present study the anti-melanoma activity of Nicotinamide (NAM), the amide form of Niacin, was assessed in vitro and in vivo. Methods Human (A375, SK-MEL-28) and mouse (B16-F10) melanoma cell lines were used for in vitro investigations. Viability, cell-death, cell-cycle distribution, apoptosis, Nicotinamide Adenine Dinucleotide+ (NAD+), Adenosine Triphosphate (ATP), and Reactive Oxygen Species (ROS) levels were measured after NAM treatment. NAM anti-SIRT2 activity was tested in vitro; SIRT2 expression level was investigated by in silico transcriptomic analyses. Melanoma growth in vivo was measured in thirty-five C57BL/6 mice injected subcutaneously with B16-F10 melanoma cells and treated intraperitoneally with NAM. Interferon (IFN)-γ-secreting murine cells were counted with ELISPOT assay. Cytokine/chemokine plasmatic levels were measured by xMAP technology. Niacin receptors expression in human melanoma samples was also investigated by in silico transcriptomic analyses. Results NAM reduced up to 90% melanoma cell number and induced: i) accumulation in G1-phase (40% increase), ii) reduction in S- and G2-phase (about 50% decrease), iii) a 10-fold increase of cell-death and 2.5-fold increase of apoptosis in sub-G1 phase, iv) a significant increase of NAD+, ATP, and ROS levels, v) a strong inhibition of SIRT2 activity in vitro. NAM significantly delayed tumor growth in vivo (p ≤ 0.0005) and improved survival of melanoma-bearing mice (p ≤ 0.0001). About 3-fold increase (p ≤ 0.05) of Interferon-gamma (IFN-γ) producing cells was observed in NAM treated mice. The plasmatic expression levels of 6 cytokines (namely: Interleukin 5 (IL-5), Eotaxin, Interleukin 12 (p40) (IL12(p40)), Interleukin 3 (IL-3), Interleukin 10 (IL-10) and Regulated on Activation Normal T Expressed and Secreted (RANTES) were significantly changed in the blood of NAM treated mice, suggesting a key role of the immune response. The observed inhibitory effect of NAM on SIRT2 enzymatic activity confirmed previous evidence; we show here that SIRT2 expression is significantly increased in melanoma and inversely related to melanoma-patients survival. Finally, we show for the first time that the expression levels of Niacin receptors HCAR2 and HCAR3 is almost abolished in human melanoma samples. Conclusion NAM shows a relevant anti-melanoma activity in vitro and in vivo and is a suitable candidate for further clinical investigations.

The Key Role of NAD+ in Anti-Tumor Immune Response: An Update

“…Infiltration of T lymphocytes in the tumor was also increased, thus indicating that Nam was able to activate the anti-tumor T cell response (31). Similar results have been obtained in a mouse model of melanoma (19), where Nam administered alone as a therapeutic agent reduced tumor growth and prolonged the survival of mice. Higher levels of IFN-g-producing cells were found in the peripheral blood of mice treated with Nam than in untreated mice.…”

“…In addition, different cytokines/chemokines were modulated in Nam-treated mice (but not in untreated mice), including an increase of IL-5 and Eotaxin and a decrease of IL-10, IL-12, IL-3 and RANTES. Thus, Nam treatment is able to increase IFN-g secretion, which is pivotal for the anti-tumor immune response, and to modulate the balance of cytokine/ chemokine in the periphery (19). These studies confirmed the role of NAD + in the activation of anti-tumor T cell response and clarified one of the mechanisms underlying T cell inactivation after NAD + depletion, centered on metabolic reprogramming.…”

“…We hypothesize that NAD + consumption may represent an additional immunosuppressive mechanism in in vitro experiments and may also represent a strategy enacted by melanoma cells in vivo in the tumor microenvironment to inhibit anti-tumor immune response. In this context, inoculation of Nam in a mouse model of melanoma significantly increased anti-tumor immune response through the induction of IFN-g secretion (19). In addition, in preclinical models of melanoma, mice receiving Nam displayed a higher T cell infiltration within the tumor than those receiving placebo (20).…”

Targeting SIRT2 Sensitizes Melanoma Cells to Cisplatin via an EGFR-Dependent Mechanism

“…In conclusion, our study [ 9 ], and others [ 50 , 51 ], suggest that SIRT2 is a tumor promoter in melanoma cells and this sirtuin is a promising target in antimelanoma therapy; these levels may influence the overall survival of melanoma patients [ 51 ]. The present study shows that inhibition of SIRT2 (shRNA-mediated knockdown and pharmacological by thiomyristoyl) resulted in sensitization of melanoma cells to the widely used anticancer drug cisplatin, most likely by targeting EGFR stability and downstream signaling.…”

Systemic Photoprotection in Skin Cancer Prevention: Knowledge among Dermatologists

“…Otherwise, about a quarter of participants confirmed they are aware of scientific studies reporting a reduction of melanoma due to systemic photoprotection, mainly vitamin D, and that this supplement was even indicated in guidelines for melanoma. A very recent study reported that nicotinamide shows a relevant antimelanoma activity in vitro and in vivo in mice, demonstrating that this molecule significantly delayed tumor growth in vivo and improved survival of melanoma-bearing mice [ 22 ]. However, no studies demonstrated that oral photoprotection has a role in melanoma prevention in humans, and no oral photoprotector is indicated in guidelines for melanoma.…”