The role of cyclin D1, BCL-2, p53 and Ki-67 in epithelial cells in the etiopathogenesis of pterygium

Abstract

Context: Pterygium is a degenerative disease that consists of conjunctival epithelia and fibrovascular tissue. Some studies suggest that there is a defect in the regulation of apoptosis in the epithelial cell cycle characterized by the development of the disease. But, still this matter being debated. Aims: In this study, the clinical, histopathological data, and the expression of the cell cycle regulator Cyclin D1, anti-apoptotic BCL-2, tumor suppressor p53, and cell proliferation marker Ki-67 were searched in pterygium samples. Subjects and Methods: The study enrolled 62 cases of primary pterygium who underwent excision between 2014 and 2017. Recurrent and pseudo-pterygium cases were excluded from series. The clinical data were obtained from the patient files and the slides were reevaluated for the histopathological data. Slides of all were stained by Cyclin D1, BCL-2, and Ki-67 by the immunohistochemical method. For each immunohistochemical marker, first the staining was determined as negative or positive. Then if there is a staining, the hot zone (the area containing more positive cells) was determined and staining percentage (SP) was assessed by counting positive cells/100 epithelial cells). Results: Solar elastosis, edema, inflammation, and epithelial dysplasia were found statistically different between the control group and the patient group (P value <0.001, <0.001, <0.001 <0.001, respectively). A significant difference was found for staining percentage (SP) of Ki-67, p53, BCL-2 between the control group and the patient group (P values <0.001, 0.002, <0.001, respectively). There were no significant differences in the SP of Cyclin D1 between the two groups (p: 0,133). Conclusions: Our results indicate an abnormal expression of p53, BCL-2 and elevated proliferation measured by Ki-67 in pterygium samples when compared to normal conjunctiva. Besides the mesenchymal changes, the increased proliferation and the failure of apoptosis in the epithelial cells participate in the development of pterygium, as well.