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Normal, benign, and malignant human prostatic tissue was cultivated in vitro. Cytopathic effects in derived epithelial cells were examined. Light microscopy revealed polykaryocyte formation, vacuolation, cytoplasmic bridges and processes, nuclear inclusions, increased acid phosphatase activity at the cell membrane of polykaryocytes as compared to mononuclear cells, and cell rounding and clumping. Electron microscopy of the polykaryocytes showed nuclear membrane proliferation and protrusion, scarlike nuclear inclusions containing microfibrils, and virus-like particles similiar to viral nucleoids and nucleocapsids. The latter were also observed in the cytoplasm. The above alterations are similar to those induced by known herpesviruses. The significance of these changes, the possibility of the presence of a latent herpesvirus in the prostate, and its role in neoplastic disease are postulated.

This report reviews the background and the present status of the MA-160 cell line. This cell line was reported to have arisen from tissue cultures of a human, benign prostatic adenoma and consequently has been used for investigations on the prostat and on hormone-dependent cells. Recent studies using chromosome analysis by banding techniques, glucose-6-phosphate dehydrogenase (G6D) electrophoretic mobility, and a specific prostatic acid phosphatase test indicate that MA-160 is not of prostatic origin but a HeLa cell contaminant, arising as a result of intraspecies cell contamination. It is suggested that whenever spontaneous transformation is observed in vitro and established cell lines are being used in the laboratory, the cells in question be thoroughly checked with the currently available chromosomal, biochemical, and cytochemical methods in order to establish their origin and to rule out interspecies and intraspecies cell contamination.

Ultrastructural changes in the prepubertal human prostatic epithelium maintained in vitro are described and are compared with the ultrastructure of the same tissue before culture. In cultured cells, rough endoplasmic reticulum and Golgi complex are poorly represented and the latter also loses its polarity. Increase in cytoplasmic microfilaments is discussed in relation to possible vitamin A deficiency. Primary and secondary lysosomes, arising from autophagy and endocytosis, occur in large numbers as autophagosomes, myelin figures, residual bodies, and multivesicular bodies. Prostatic acid phosphatase activity, an important secondary sex characteristic, is influenced by sex hormones and malignancy; since this enzyme is lysosome-associated, special emphasis is placed on lysosomal changes. Some ultrastructural changes in rough endoplasmic reticulum, Golgi complex, and the lysosomal system are similar to those observed after castration. This study presents ultrastructure of cultured cells which form the basis for studies involving neoplastic transformation, aging, and hormonal manipulation using an in vitro model. This is necessitated by the absence of an in vivo animal model for prostatic neoplasia; hence studies on prostatic oncogenesis, and age-related phenomenon, must be done on cells in vitro. Significance of this study is enhanced by the fact that normal human prepubertal prostate has not been studied before and normal viable prostate is generally not available for investigations.

The objective of this report is to demonstrate that only slight and superficial similarities exist between true virus particles and secretion granules in human prostatic epithelium. In spite of this, secretion granules have sometimes been called virus or virus-like particles. With the current interest in the possible role of viruses in the etiology of some human cancers, many investigations are in progress in search of human tumor viruses. The presence of RNA virus particles in normal as well as tumor tissues derived from animals and man, further complicates the picture. Also, in view of the fact that recent studies indicate an association between herpes simplex type 2 virus and cervical cancer, the possibility of the involvement of the same virus, which has a venereal mode of transmission, in prostatic and other genitourinary cancers in the human male has been considered. Investigators with peripheral interests in such studies are cautioned against making quick decisions on the nature of the "virus-like particles" often observed in secretory cells because these particles often happen to be cell organelles.