Changes of phenotypic expression of prostatic antigen in secondary transitional cell carcinoma of the prostate: Evidence for induction phenomenon as a mechanism for acquisition of prostatic antigens in prostatic transitionalcell carcinoma

BACKGROUND. In vitro and experimental studies of mesenchymal-epithelial int eraction for the prostatic stroma have demonstrated that the prostatic stro ma is capable of inducing the nonprostatic epithelium to acquire many featu res of prostatic epithelium. We investigated whether this phenomenon could be observed in vivo in human prostatic stroma. MATERIALS AND METHODS. Sixty transitional cell carcinoma (TCC) of the urina ry bladder: (a) 20 with glandular lumen; (b) 20 without glandular lumen: (c ) 10 mixed TCC-adenocarcinoma (ACA); and (d) 10 with synchronous or metachr onous TCC of the prostate; and three primary TCC of the prostate were exami ned and submitted for immunostaining for prostatic acid phosphatase (PAP) a nd prostatic specific antigen (PSA). RESULTS. There was a spectrum of immunostaining for PSA ranging from negati ve reactivity In TCC without glandular lumen of the urinary bladder, to foc al and weak reactivity in single cells with varying degrees of nonmucinous glandular differentiation and to strong reactivity in groups of cells in pr imary and synchronous or metachronous TCC in the prostate. The areas of car cinoma geographically closest to the prostate and with the most extensive n onmucinous glandular differentiation displayed the most frequent and strong est immunoreactivity for PSA. The immunoreactivity for PAP was usually stro nger than far PSA. Four cases of TCC and mixed TCC-ACA were immunoreactive only for PAP. Furthermore, there was a change in the phenotype of TCC in th e urinary bladder as ii spread into the prostate. For 10 TCC in the urinary bladder with synchronous or metachronous tumor in the prostate, all TCC in the urinary bladder were negative for PAP and PSA, whereas six TCC in the prostate were focally positive. CONCLUSIONS. The spectrum of immunoreactivity for PAP and PSA and the chang e in immunoreactivity of TCC of the urinary bladder as it spreads into the prostate are likely induced by the prostatic stroma through the mechanism o f mesenchymal-epithelial interaction. Prostate 47:172-182, 2001. (C) 2001 W iley-Liss, Inc.