Characterization of tumour effusions of the Dunning R-3327 rat prostate adenocarcinoma

Enhanced production of prostaglandins (PG) by experimentally-induced and naturally occurring tumours and their effect on tumour growth and immunosurveillance have been noted. Directed toward further evaluation of the relationship between prostatic tumour growth and its milieu, i.e. its microenvironment, the possible correlation between levels of PG, tumour size and metastatic potential was investigated. For this purpose, the levels of PGE₂ and PGF(2α) in peritumoural exudates of 3 tumour sublines of the Dunning R-3327 rat prostate adenocarcinoma: i) R-3327 Mat Lylu - fast growing and highly metastatic; ii) R-3327G - fast growing and poorly metastatic and iii) R-3327H - slow growing and poorly metastatic, were measured. The level of PGF(2α) was highly variable with no significant difference being noted between the tumour sublines. The mean values of PGF(2α) were, however, higher in the smaller tumours within each of the sublines. The levels of PGE₂ were considerably higher in Mat Lylu exudates than those from the non-metastasing R-3327G and H sublines. A vasodilator and regulator of immunological responsiveness, PGE₂ may function as a modulator of tumour metastases. In comsonance with studies by others, elevated levels of PGE₂ may possibly serve as a prognostic marker for the high metastatic potential of neoplastic cells.