Bevacizumab modulates epithelial-to-mesenchymal transition in the retinal pigment epithelial cells via connective tissue growth factor up-regulation

To investigate the effect of bevacizumab treatment on connective tissue growth factor (CTGF) expression and the induction of epithelial-to-mesenchymal transition in ARPE-19 cells and human donor retinal pigment epithelium (HRPE) cells in vitro.

We quantitated the protein and gene expression level of CTGF by ELISA. The effect of Fc-Fc receptor (Fc-FcR) interaction on CTGF expression was evaluated by CD64 siRNA silencing. Expression of epithelial-to-mesenchymal transition markers, alpha-smooth muscle actin (α-SMA) and zona occludens protein (ZO-1) was evaluated by Western blot. Cell migration and collagen gel contraction assay were examined by light microscopy, and collagen production was measured by ELISA.

Bevacizumab stimulation increased CTGF expression in ARPE-19 and HRPE cells in a dose-dependent manner. CD64 gene silencing inhibited the effect of bevacizumab-induced CTGF up-regulation. Bevacizumab increased the expression of α-SMA and decreased the expression of ZO-1 in ARPE-19 cells. Bevacizumab also caused the release of type-1 collagen and increased cell migration and contraction of collagen.

Bevacizumab exerts pro-fibrotic effects on human RPE cells at clinical doses by up-regulation of CTGF expression via an Fc-FcR interaction. This effect of bevacizumab may be one of the underlying mechanisms involved in age-related macular degeneration therapy or intravitreal bevacizumab-associated complications.