Silencing Id-1 inhibits lymphangiogenesis through down-regulation of VEGF-C in oral squamous cell carcinoma

Our previous study demonstrated that overexpression of Id-1 (inhibitor of differentiation/DNA binding) was associated with lymphatic metastasis in human oral squamous cell carcinoma (OSCC). In this study, we further unveiled the association of Id-1 with vascular endothelial growth factor-C (VEGF-C) and peritumoral lymphatic vessel density (PLVD), and the effect of silencing Id-1 on inhibiting lymphangiogenesis in OSCC. We found that Id-1 was associated with VEGF-C (r=0.569, p<0.001) and PLVD (r=0.240, p<0.001) in OSCC. Lentivirus-mediated RNA interference targeting Id-1 in an OSCC cell line Tca8113 resulted in down-regulation of VEGF-C (p=0.003, 0.007). Moreover, when Id-1 was suppressed by injecting Id-1-siRNA-lentivirus into the transplanted tumors in nude mice, VEGF-C was down-regulated (p=0.018) and the PLVD decreased (p=0.001). Our results suggest that Id-1 was correlated with lymphangiogenesis in OSCC. Silencing Id-1 could inhibit lymphangiogenesis through down-regulation of VEGF-C and it might be a promising treatment modality for the lymphatic metastasis of OSCC.