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Visfatin/eNampt is a novel adipokine, secreted by visceral and subcutaneous fat, which could be involved in the development of obesity-associated cancer. Only few studies revealed reactive oxygen species (ROS)-dependent action of visfatin in endothelial cells, myotubes and melanoma cells. The potential pro-apoptotic properties of visfatin/eNampt in human colorectal HCT-116 cells remain unknown. The aim of the study was to examine the effects of visfatin/eNampt on cell viability along with the determination of apoptosis/necrosis extent and ROS level in HCT-116 cells. Additionally antioxidant enzymes' activities (i.e catalase (CAT), gluthatione peroxidase (GSH-Px)), and lipid peroxidation intensity in HCT-116 cells line was evaluated. Viability of HCT-116 cells was decreased after visfatin/eNampt treatment for 24 hours. The number of apoptotic cells in tested cells treated with increasing visfatin/eNampt concentrations (10, 100, 250 ng/ml) was elevated compared to untreated cells (6.4%, 9.7%, 16% vs. 3.2%; respectively). After 24 hours in the visfatin/eNampt treated group (10 - 100 ng/ml) CAT and GSH-Px activities significantly increased and this observation was accompanied by the decrease of ROS level when compared to the control group. Interestingly ROS level (using DCF detection technique) and lipid peroxidation ratio were increased in cells stimulated by visfatin/eNampt in concentration of 250 ng/ml along with the decreased activity of selected antioxidant enzymes when compared to remaining study groups, including control. We concluded that visfatin/eNampt induces decrease of cell viability and apoptosis boost in human colorectal cancer HCT-116 cells line. Visfatin/eNampt affected the level of ROS as well as antioxidant capacity, however the association of ROS level and apoptosis rate was not linear. The role for visfatin/eNampt in cancer redox status in vitro may provide a greater insight into the association between fat derived visfatin/eNampt and its endocrine action in colorectal carcinoma 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.