Flow cytometric analysis of the response of the r3327-g rat prostatic adenocarcinoma to endocrine manipulation

The technique of flow cytometric DNA histogram analysis (FCM) shows there to be two distinct cell populations (diploid vs aneuploid) in the poorly differentiated R3327‐G rat prostatic adenocarcinoma. The following study compares tumor weight measurements with several FCM computer‐based methods designed to determine rapidly the proliferative status of tumors. Hypophysectomy, bilateral adrenalectomy, orchiectomy, sham operations, or diethyl‐stilbestrol treatments were initiated when the tumors were palpable (day 21) and continued until the tumors were excised (day 52). Hypophysectomy, orchiectomy, adrenalectomy, and diethylstilbestrol treatments all resulted in significant inhibition by tumor weight. Quantitation of the percentage of mid‐S phase aneuploid cells by summation gave the best correlation with tumor weight. Tumors grown in hypophysectomized, orchiectomized, adrenalectomized, or diethylstilbestrol‐treated animals showed a significant reduction in the proportion of mid‐S phase cells as compared with controls. The calculation of the percentage of all aneuploid cells was significantly reduced in hypophysectomy, orchiectomy, and diethylstilbestrol‐treated animals. However, tumors grown in adrenalectomized animals were not significantly different from controls by this method. Adrenalectomy was found to be the least effective form of therapy, and this was reflected in all of the parameters measured. These data show that FCM analysis may be useful in the quantitation of prostatic carcinoma response to therapy.