Elevated proto-oncogene and collagen mRNA expression in PVR retinas

Abstract

Purpose: Retinal detachment is often accompanied by proliferation and migration of retinal cells and by increased synthesis of structural proteins, known as proliferative vitreoretinopathy (PVR). Herein we investigate the messenger RNA (mRNA) expression of proto-oncogenes responsible for cell proliferation and of structural proteins that have a role in membrane formation.

Methods: Retinal samples were obtained from patients undergoing vitreoretinal surgery for the treatment of retinal detachment complicated by PVR. Normal human control retinas were obtained from cornea donors. The mRNA expression of the proto-oncogenes c- myc, c- fos and the proliferation marker Ki67, as well as of collagen type III and type IV, were investigated using the ribonuclease protection assay.

Results: Ki67 mRNA expression was not detectable in either sample type, but c- fos and c- myc mRNA expression was found in normal and PVR retinas. Whereas the expression of c- myc showed a marginal increase, the up-regulation in c- fos expression was strongly significant (5.07-fold). The mRNA of collagen type III was detectable at widely varying levels in all the PVR retinas but was found in only 2 of the 16 analysed normal samples. Collagen type IV mRNA was expressed in both PVR and control samples but was higher (2.21-fold) in the PVR retinas.

Conclusions: These results indicate that an up-regulation of the proto-oncogene c- fos occurs in human PVR retinas. An increase in mRNA expression of collagen types III and IV takes place simultaneously. These changes in mRNA expression appear to be mainly connected to the initiation of cell proliferation, dedifferentiation and formation of tractional membranes.