RNA Interference-Mediated Vascular Endothelial Growth Factor-C Reduction Suppresses Malignant Progression and Enhances Mitomycin C Sensitivity of Bladder Cancer T24 Cells

Vascular endothelial growth factor-C (VEGF-C) has been found to be significantly associated with lymphangiogenesis and regional lymph node metastasis in various human tumors. The present work was aimed to explore the role of VEGF-C in malignant progression of human bladder cancer T24 cell line. First, the expression of VEGF-C in T24 cells was detected by western blotting. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was employed to measure the cellular proliferation after treatment with various concentrations of recombinant human VEGF-C (rhVEGF-C). Then, lentivirus vector-based RNA interference (RNAi) was used to inhibit VEGF-C expression of T24 cells. The alterations of T24 cells regarding proliferation, invasiveness, and the apoptosis induced by mitomycin C (MMC) were evaluated. The results showed that the proliferation rate of T24 cells rose from 27.3% to 65.0%, with increasing rhVEGF-C concentration. T24 cells stably transfected with VEGF-C small interference RNA showed 85% reduction in VEGF-C mRNA expression (p<0.05). The VEGF-C protein level was significantly downregulated (p<0.05) and the growth and invasiveness were also inhibited (p<0.05) compared with the control group. Further, the inhibition of VEGF-C expression markedly enhanced the apoptosis of T24 cells induced by MMC (p<0.05). These were associated with the decreased ratio of Bcl-2/Bax, activation of Caspase-3, decreased expression of MMP-9, as well as the downregulation of phosphorylated p38 MAPK and Akt. The present study suggests that VEGF-C can enhance the proliferation and invasiveness of bladder cancer T24 cells, which is due to suppression of apoptosis and facilitation of migration, accompanied with upregulation of p38 MAPK and Akt phosphorylation. RNAi targeting VEGF-C could effectively suppress malignant progression and enhance chemosensitivity of T24 cells. Thus, inhibition of VEGF-C expression is a potential and promising therapeutic strategy for bladder cancer.