RESPONSE OF CELL-GROWTH AND RETINOIC ACID RECEPTOR EXPRESSION TO RETINOIC ACID IN NEOPLASTIC AND NONNEOPLASTIC PROSTATE CELL-LINES

BACKGROUND. Retinoic acid (RA) is recognized as an inhibitor of tumori genesis, but conversely, has also been shown to act as a tumor enhance r, therefore its role in prostate tumor cell growth was investigated. METHODS. The response of two human prostate tumor cell lines (PC-3 and DU-145), and cell lines derived from a well-differentiated canine pro state adenocarcinoma (CPA) and normal canine prostate epithelium (CAFE ) to all-trans RA was determined using growth curve analysis. Addition ally, the constitutive expression and RA-challenged expression of reti noic acid receptors (RARs) -alpha, -beta, and -gamma mRNA was examined using Northern blotting techniques. RESULTS. In response to all-trans RA, the PC-3 and DU-145 cell lines showed considerable growth promoti on, while CAFE and CPA cell growth was dramatically inhibited. Each ce ll line expressed RAR alpha and RAR gamma, with either negligible or n o RAR beta transcripts being detected. RAR alpha and -gamma mRNAs dete cted in the four cell lines were variably regulated in response to RA, and no distinct patterns of RAR regulation that could be related to c ell growth responses were observed. CONCLUSIONS. The data indicates th at no simple association exists between the expression or regulation o f RAR subtype mRNAs and the divergent growth responses to RA displayed by the prostate cell lines. (C) 1997 Wiley-Liss, Inc.