Cyclooxygenase 1 and 2 mRNA and protein expression in the Gallus domesticus model of ovarian cancer.

OBJECTIVE

Our purpose was to determine the mRNA and protein expression of cyclooxygenase 1 (COX-1) and cyclooxygenase 2 (COX-2) in ovarian tumors and normal ovaries of the hen, which is an excellent model for human ovarian cancer. Tissue concentrations of prostaglandin E(2) (PGE2) and PGE2 metabolites were also determined.

METHODS

Tissue was obtained from ovarian tumor (n = 18) and normal ovary (n = 29) of 2- to 4-year old Single-comb White Leghorn hens. Quantitative real-time PCR with Sybr Green was used to quantify the mRNA expression of COX-1 and COX-2, using 18S expression as an internal control for COX normalization. Immunohistochemistry using antibodies for COX-1 and COX-2 was used to localize protein expression of each isoform in a subset of tumor (n = 5) and normal samples (n = 6). For determination of tissue prostaglandin concentration, tissue was obtained from ovarian tumor (n = 8) and normal ovary (n = 8). PGE2 and PGE2 metabolites were measured using competitive enzyme immunoassays (EIAs).

RESULTS

Our results indicate that COX-1 mRNA expression is significantly higher (P < 0.05) in ovarian tumor samples compared to normal ovaries while there is no significant difference in expression of COX-2 between the samples. Immunohistochemistry results support this finding and show COX-1 expression only in tumor samples and COX-2 expression unchanged between normal ovary and tumor samples. PGE2 levels are significantly higher (P < 0.05) in tumor samples compared to normal ovaries, and there is no significant difference in PGE2 metabolite levels between the samples.

CONCLUSION

These findings may implicate COX-1 as a suitable target for the prevention or treatment of ovarian cancer.