Vitamin C has inconsistent effects on malignant
tumor cells, which vary from growth stimulation to apoptosis induction. It is well known that
melanoma cells are more susceptible to
vitamin C than any other
tumor cells, but the precise mechanism remains to be elucidated. In the present study, the proliferation of B16F10
melanoma cells was suppressed by
vitamin C, which induced growth arrest in a dose-dependent manner without cytotoxic effects. Therefore, we investigated the changes in cell cycle distribution of B16F10
melanoma cells by staining DNAs with
propidium iodide (PI). The growth inhibition of B16F10
melanoma by
vitamin C was associated with an arrest of cell cycle distribution at G1 stage. In addition, the levels of p53-p21Waf1/Cip1 increased during G1 arrest, which were essential for
vitamin C-induced cell cycle arrest. The increased p21Waf1/Cip1 inhibited CDK2. Moreover, the activity of p53-p21Waf1/Cip1 pathway was closely related with the activation of
checkpoint kinase 2 (Chk2). Inhibitor of the PI3K-family,
LY294002 and the ATM/ATR inhibitor,
caffeine, blocked
vitamin C-induced growth arrest in B16F10
melanoma cells. These results suggest that
vitamin C might be a potent agent to inhibit proliferative activity of
melanoma cells via the regulation of Chk2-p53-p21Waf1/Cip1 pathway.