Expression of cyclooxygenase-1 and -2 in naturally occurring squamous cell carcinomas in horses.

This research investigates the expression of cyclooxygenase (COX)-1 and -2 in squamous cell carcinomas (SCCs) and normal tissues in horses, revealing that both these proteins are present in SCC-affected and healthy tissues, unlike in other species. The study suggests further research to understand the influence of COX-2 inhibitors on cancer treatment in horses.

Introduction and Methodology

• The researchers studied the expression of cyclooxygenase (COX)-1 and -2 in naturally occurring squamous cell carcinomas (SCCs) in horses. Their objective was to understand how horses might differ from other species in this aspect.
• They collected tissue samples from 14 horses affected by SCC in different regions like conjunctiva, vulva, prepuce, and penis during surgical excision. They also gathered tissue samples from comparable body regions in 5 horses euthanized for reasons other than neoplasia.
• These tissue samples were snap frozen in liquid nitrogen and stored at -80 degrees Celsius until analysis.
• The researchers extracted protein from the frozen tissues, and performed western blot analyses. Abnormal tissues and nonneoplastic tissues from each body region were run on the same blot, in triplicate.
• Molecular-weight markers and COX-1 and 2 ovine standards served as positive control samples, while no negative control samples were used.

Results

• The analysis revealed that all tissues, including the nonneoplastic and SCC tissues, expressed both COX-1 and -2 proteins.
• This expression of COX proteins in both normal and SCC-affected tissues in horses was identified as markedly different from patterns observed in other species.

Conclusions and Further Research

• Based on the results, the reason for the potential benefit of COX-2 inhibitors in horses and other species is not clear. However, it prompts further research into evaluating the efficacy of COX-2 inhibitors as possible cancer treatments in horses.
• It was also suggested that investigation into the mechanisms of tumor development in horses should be carried out to improve the understanding of this disease and determine how the mechanisms differ from those in other animals.