Abstract
Purpose :
Retinal pigment epithelial (RPE) cells maintain retinal integrity and homeostasis. In the presence of hypoxia they elaborate various angiogenic factors, including VEGF-A, which is involved in pathogenesis of neovascularization in various retinal disorders. Hypoxia also affects mitochondria that play a major role in cell metabolism. The transcriptional co-activator PGC-1A induces mitochondrial biogenesis and regulates removal of mitochondrial reactive oxygen species (ROS) by-products.
The purpose was to determine if Bevacizumab altered expression levels of VEGF-A and PGC-1A in ARPE-19 cultures, in order to understand its role in angiogenesis and mitochondrial metabolism. The ARPE-19 cell line (www.atcc.org) provides a dependable and widely used RPE model for in-vitro testing. It has been validated in our laboratory to express RPE markers.
Methods :
ARPE-19 cells were cultured for 24 hours, treated with the therapeutic concentration 1.25 mg (1x) or twice the therapeutic concentration 2.5 mg (2x) of Bevacizumab for 24 and 48 hours The RNA was extracted and qRT-PCR used to measure expression levels of VEGF-A and PGC-1A. Data were analyzed by the ΔΔCt Method. Fold change was calculated and p value < 0.05 was considered significant.
Results :
ARPE-19 cells exposed to 1x Bevacizumab showed decreased expression of PGC1-A after 24 (0.37-fold, p = 0.0003) and 48 hours treatment (0.82-fold, p = 0.0287) compared to untreated cultures. The decreased expression was sustained following exposure to 2x Bevacizumab for 24 (0.49-fold, p = 0.0012) and 48 hours (0.44-fold, p = 0.0004) compared to controls. The 1x Bevacizumab-treated cultures had increase in VEGF-A expression at 24 (1.5-fold, p = 0.193) and 48 hours (1.26-fold, p = 0.0374). The 2x Bevacizumab cultures showed increase in VEGF-A levels at 24 (1.66-fold, p = 0.0046) and 48 hours (1.63-fold, p = 0.0032).
Conclusions :
The variable decreased PGC-1A expression at 24 and 48 hours in the 1x Bevacizumab treated cultures became sustained in the 2x Bevacizumab treated cultures. The 1x and 2x Bevacizumab treated cultures showed increased expression of VEGF-A after 24 and 48 hours. These findings show that Bevacizumab may influence mitochondrial biogenesis and homeostasis along with affecting the angiogenesis pathways.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.