VEGFR and EGFR inhibition increases epithelial cellular characteristics and chemotherapy sensitivity in mesenchymal bladder cancer cells

The present study investigated the effect of VEGFR and EGFR inhibition via vandetanib (Zactima™) on epithelial-mesenchymal transition (EMT) in bladder cancer. Markers of EMT (EGFR, VEGR, E-cadherin and vimentin) were interogated by Western blotting at baseline and after treatment with EGF, VEGF, vandetanib, cisplatin, or their combination using representative epithelial- and mesenchymal-type human bladder cancer cells. Morphological changes induced by these treatments were examined by microscopy over various time courses. The effect of these changes on cisplatin chemotherapy sensitivity was assessed by MTT assay. RT4 and HTB3 cells had epithelial features while CRL1749 and J82 cells had mesenchymal features. After treatment with EGF, the epithelial-type cells demonstrated increased intercellular separation and pseudopodia, with these changes blocked by vandetanib. In contrast, the mesenchymal cells did not exhibit any morphological changes with the EGF treatment but adopted a clustered/epithelial appearance after the administration of vandetanib. Western blotting shows that treatment of epithelial cells with vandetanib increased the expression of E-cadherin. In comparison, mesenchymal cells demonstrated decreased vimentin expression with the treatment of vandetanib in the presence of EGF and VEGF. Improved growth inhibition was seen in the epithelial cells but not in mesenchymal cells with the concurrent treatment of vandetanib and cisplatin. Sequential treatment of mesenchymal cells with vandetanib followed by cisplatin demonstrated synergy with improved cisplatin activity. The findings offer a novel role of vandetanib on the EMT in bladder cancer, providing insight into EMT in bladder cancer.