Chronic alcohol consumption stimulates VEGF expression, tumor angiogenesis and progression of melanoma in mice

The mechanisms of alcohol-induced cancer in humans are unclear. We used the immunocompetent mice implanted with B16F10 cells to evaluate the effects of physiologically relevant EtOH intake on tumor growth and angiogenesis of melanoma. Six-wk-old male mice (C57BL/6J) were given 1% EtOH in drinking water for 12-hrs during the night which was then replaced with regular water during the remaining 12-hrs each day for 4 wks (n = 10). The control mice received regular drinking water only. In the second week, all mice were inoculated subcutaneously on the right proximal dorsal with 5 x 10(5) B16F10 cells. In the end, the tumors were isolated for measuring tumor size, average microvascular density (AMVD) using CD31 immunohistochemistry, and the expression of VEGF and its receptor (Flt-1) using Northern blot, ELISA, and immunohistochemistry. EtOH intake caused a 2.16-fold increase in tumor weight over the control (4.81 +/- 0.39 vs. 2.23 +/- 0.48 g; n = 10; p = 0.003), a 2.02-fold increase in AMVD (60.63 +/- 5.56 vs. 30.01 +/- 7.41/mm(2); p = 0.0014), and a significant increase in VEGF mRNA and protein expression plus Flt-1 protein levels in melanoma compared to the control group (p < 0.01). These results suggest that progression of melanoma growth and angiogenesis may be mediated by upregulation of VEGF and Flt-1, especially under the influence of EtOH.