Primary and Transplantable Adenocarcinomas of the A × C Rat Ventral Prostate Gland: Morphologic Characterization and Examination of C19-Steroid Metabolism by Early-Passage Tumors2

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Abstract
Spontaneous adenocarcinomas of the ventral prostate gland observed with a frequency of 70% in a population of 33 aged (30-46 mo. old), virgin male A .times. C rats. Some of these adenocarcinomas involved multiple acini, and in 6 rats the lesions were bilateral. Atypical hyperplasia of ventral prostate acinar epithelium was also observed. It consisted of thickened epithelium in which various numbers of epithelial cells had swollen, foamy, periodic acid-Schiff-positive cytoplasm and condensed, eccentric nuclei. The atypical hyperplasia was found in association with both atrophic and neoplastic epithelium. Treatment with exogenous testosterone caused the development of columnar epithelium in many of the ventral prostate acini, increased the frequency of detected adenocarcinoma and amplified the anaplastic characteristics of neoplastic cells. The malignant character of these spontaneous prostate adenocarcinomas was demonstrated by their transplantability to male A .times. C rats. The transplantable prostate adenocarcinomas were composed of neoplastic epithelial cells that were arranged in cribriform patterns and supported by a delicate connective tissue stroma. Highly anaplastic epithelial cells growing in sheets were also present. When compared to nonneoplastic ventral prostate glands of senescent A .times. C rats, testosterone metabolism by the transplantable adenocarcinomas was distinguished by a shift to more prominent elaboration of 17-ketosteroids, principally 4-androstenedione and a concomitant decreased production of 5.alpha.-reduced 17.beta.-hydroxysteroids. Most acid phosphatase activity of the transplantable adenocarcinomas was tartrate-inhibitable. These early-passage tumors retain biochemical properties characteristic of differentiated prostate acinar epithelium.