Cyclooxygenase-2 expression and prostaglandin E-2 synthesis are up-regulated in carcinomas of the cervix: A possible autocrine/paracrine regulation of neoplastic cell function via EP2/EP4 receptors

The prevalence of cervical cancer in South African women is reported as bei ng the highest in the world, occurring, on the average, in 60 of every 100, 000 women. Cervical cancer is thus considered an important clinical problem in sub-Saharan Africa. Recent studies have suggested that epithelial tumor s may be regulated by cyclooxygenase (COX) enzyme products. The purpose of this study was to determine whether cyclooxygenase-a (COX-2) expression and PGE(2) synthesis are up-regulated in cervical cancers. Real-time quantitat ive RT-PCR and Western blot analysis confirmed COX-2 ribonucleic acid and p rotein expression in all cases of squamous cell carcinoma (n = 8) and adeno carcinoma (n = 2) investigated. In contrast, minimal expression of COX-2 wa s detected in histologically normal cervix (n = 5). Immunohistochemical ana lyses localized COX-2 expression and PGE(2) synthesis to neoplastic epithel ial cells of all squamous cell (n = 10) and adenocarcinomas (n = 10) studie d. Immunoreactive COX-2 and PGE(2) were also colocalized to endothelial cel ls lining the microvasculature. Minimal COX-2 and PGE(2) immunoreactivity w ere detected in normal cervix (n = 5). To establish whether PGE(2) has an a utocrine/paracrine effect in cervical carcinomas, we investigated the expre ssion of two subtypes of PGE, receptors, namely EP2 and EP4, by real-time q uantitative RT-PCR. Expression of EP2 and EP4 receptors was significantly h igher in carcinoma tissue (n = 8) than in histologically normal cervix (n = 5; P < 0.01). Finally, the functionality of the EP2/EP4 receptors was asse ssed by investigating cAMP generation after in vitro culture of cervical ca ncer biopsies and normal cervix in the presence or absence of 300 nmol/L PG E(2). cAMP production was detected in all carcinoma tissue after treatment with exogenous PGE(2) and was significantly higher in carcinoma tissue (n = 7) than in normal cervix(n = 5; P < 0.05). The fold induction of cAMP in r esponse to PGE, was 51.1 +/- 12.3 in cervical carcinoma tissue compared wit h 5.8 +/- 2.74 in normal cervix. These results confirm that COX-2, EP2, and EP4 expression and PGE(2) synthesis are up-regulated in cervical cancer ti ssue and suggest that PGE(2) may regulate neoplastic cell function in cervi cal carcinoma in an autocrine/paracrine manner via the EP2/EP4 receptors.