Cyclooxygenase-1 &-2 and Ki67 Expression in Early-and Advanced-Stage Ovine Pulmonary Adenocarcinomas

Ovine pulmonary adenocarcinoma (OPA), is a common disease in places where sheep are reared. Its Diagnosis can be done using histopathology, or through the detection of exJSRV nucleic acid. This study aimed to asses Cyclooxygenase-1 (COX-1) and Cyclooxygenase-2 (COX-2) expression in the early and advanced stages of OPA using immunohistochemistry and Western blotting. Lung tissue samples of eighteen sheep bearing symptoms were investigated for this purpose. Tissues were routinely processed and serial sections were obtained. Haematoxylin & Eosin (H&E) staining, Avidin-Biotin Peroxidase Technique (ABC) with commercial antibodies for JSRV capsid protein (JSRV CA), COX-1, COX-2, and Ki67 was performed on the sections. COX-1, and COX-2 expression levels were determined by Western Blotting. All tissues were tested with RT-PCR and further analyzed for confirmation of exJSRV nucleic acid presence. Nine sheep samples were determined to be early stage and other nine were advanced-stage using histopathological analyses. All early-stage and advanced-stage OPA cases showed positive labelling for JSRV CA, Ki67, COX-1, and COX-2. COX-1, COX-2 and Ki67 immunopositivity levels were found to be statistically higher in advanced-stage OPA compared to early-stage OPA. In Western blot analyses, COX-1 and COX-2 expression levels were found to be higher in advanced-stage OPA infections compared to early-stage OPA infections. It was therefore concluded that chronic inflammation and alveolar macrophages could contribute to the development of OPA. Similar to lung cancer in humans, the use of COX inhibitors for the treatment of OPA is thought to be highly effective.