Pituitary adenylate cyclase activating polypeptide (PACAP) in human ovarian cancers

Synthesis of regulatory peptides has been described in a number of ovarian tumours. The recently isolated neuropeptide pituitary adenylate cyclase activating polypeptide (PACAP) is expressed transiently in steroidogenic cells of normal rat ovary. In order to evaluate if ovarian tumours also synthesize PACAP, we investigated the expression and processing of pro-PACAP in 11 serous cystadenocarcinomas, one non-differentiated carcinoma, one borderline malignant and four adenomas. Using sequence specific radioimmunoassays and gel chromatography, we found that all tumours expressed PACAP-38 immunoreactivity. Ovarian cancers contained higher (P < 0.03) concentrations (median 0.9 pmol/g, range 0.5-1.6 pmol/g, n = 13) than benign tumours (median 0.5 pmol/g, range 0.4-0.6 pmol/g, n = 4). Chromatography showed that the tumours contained PACAP-38 and PACAP-31-38 suggesting a rather complete processing. By immunohistochemistry, few scattered PACAP positive cells in small clusters or as single cells were identified in the tumours.