Bevacizumab modulates retinal pigment epithelial-to-mesenchymal transition via regulating Notch signaling

To investigate the effect of bevacizumab treatment on Notch signaling and the induction of epithelial-of-mesenchymal transition (EMT) in human retinal pigment epithelial cells (ARPE-19) in vitro.

In vitro cultivated ARPE-19 cells were treated with 0.25 mg/mL bevacizumab for 12, 24, and 48h. Cell morphology changes were observed under an inverted microscope. The expression of zonula occludens-1 (ZO-1), vimentin and Notch-1 intracellular domain (NICD) was examined by immunofluorescence. The mRNA levels of ZO-1, α-SMA, Notch-1, Notch-2, Notch-4, Dll4, Jagged-1, RBP-Jk and Hes-1 expression were evaluated with quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of α-SMA, NICD, Hes-1 and Dll-4 expression were examined with Western blot.

Bevacizumab stimulation increased the expression of α-SMA and vimentin in ARPE-19 cells which changed into spindle-shaped fibroblast-like cells. Meanwhile, the mRNA expression of Hes-1 increased and the protein expression of Hes-1 and NICD also increased, which Notch signaling was activated. The mRNA expression of Notch-1, Jagged-1 and RBP-Jk increased at 48h, and while Dll4 mRNA and protein expression did not change after bevacizumab treatment.

Jagged-1/Notch-1 signaling may play a critical role in bevacizumab-induced EMT in ARPE-19 cells, which provides a novel insight into the pathogenesis of intravitreal bevacizumab-associated complication.