Xenografted small cell undifferentiated cancer of prostate: possible common origin with prostatic adenocarcinoma.

The first xenograft line of small cell undifferentiated carcinoma of the prostate (UCRU-PR-2) has been established and characterized. The donor tumor and the xenograft share the common morphological and ultrastructural features of small cell undifferentiated carcinoma (including neurosecretory granules) but also elaborate epithelial membrane antigen and carcinoembryonic antigen, in addition to neurone-specific enolase. The line expresses a diploid DNA complement. Androgen and estrogen receptors are not expressed, although prostatic acid phosphatase is present in sera from tumor-bearing mice in low levels. From these studies, we postulate a possible common stem cell origin for adenocarcinoma and small cell undifferentiated carcinoma of the prostate; further studies of a cell line derived from this tumor may clarify the issue.