Exogenous administration of visfatin affects cytokine secretion and increases oxidative stress in human malignant melanoma Me45 cells

Visfatin has recently been established as a novel adipokine that is predominantly expressed in visceral fat. Recombinant visfatin has immunomodulating properties, which can activate human leukocytes in vitro to induce cytokine production (IL-1β, TNF-α, and IL-6). Only few studies have investigated the effect of visfatin on prostate, breast, ovarian cancer as well as astrocytoma cell biology. There have been no studies on the cytokine secretion in human melanoma cells in response to visfatin stimulation along with intracellular protein kinases inhibitors. ELISA assay was performed in supernatants of Me45 cells stimulated with visfatin in the presence or the absence of specific pharmacological inhibitors of the indicated protein kinases (p38, MEK 1, PI3k and JAK kinase) and nuclear factor kappa B (NK-κB) inhibitor. Intracellular reactive oxygen species level was measured in 2', 7'-dichlorodihydrofluorescein diacetate (H₂DCF-DA)-loaded cells using a fluorescent measurement system. For determination of NF-κB activation, activated NF-κB p65 subunit was determined using an EZ-TFA-detect chemiluminescent transcription factor assay. We report that visfatin led to the significant increase in IL-6 and IL-8 level in culture supernatants of human malignant melanoma Me45 cells. Additionally visfatin resulted in the increase of the intracellular reactive oxygen species level. PI3k and NF-κB pathways were activated upon visfatin stimulation. The results may reflect the fact that PI3k pathway stimulation by visfatin may further lead to NF-κB activation and pro-inflammatory response.