Effect of Genistein on vasculogenic mimicry formation by human uveal melanoma cells

Background: Vasculogenic mimicry (VM) was increasingly recognized as a form of aggressive melanoma acquiring blood supply. Genistein had attracted much attention as a potential anticancer agent. Therefore, we examined the effect of Genistein on VM in human uveal melanoma cells. Methods: VM structure was detected by periodic acid-Schiff (PAS) staining for uveal melanoma C918 cells cultured on the three-dimensional type I collagen gels after exposed to Genistein. We used reverse transcription polymerase chain reaction (RT-PCR) and Western Blot analysis to examine the effect of Genistein on vascular endothelial cadherin (VE-cadherin) mRNA and protein expression. The nude mice models of human uveal melanoma C918 cells were established to assess the number of VM using immunohistochemical and PAS double-staining. Results: Genistein inhibited the survival of C918 cells in vitro. The ectopic model study showed that VM in tumor tissue sections were significantly reduced by Genistein in vivo. In vitro, the VM structure was found in control, 25 and 50 mu M Genistein-treatment groups but not in 100 and 200 mu M. RT-PCR and Western Blot showed that 100 and 200 mu M concentration of Genistein could significantly decrease VE-cadherin mRNA and protein expression of C918 cells compared with control (P < 0.05). However, the 25 and 50 mu M Genistein slightly decreased the VE-cadherin level in vitro (P > 0.05). Conclusion: Genistein inhibits VM formation of uveal melanoma cells in vivo and in vitro. One possible underlying molecular mechanism by which Genistein could inhibit VM formation of uveal melanoma is related to down-regulation of VE-cadherin.