Site-specific growth of the prostate xenograft line UCRU-PR-2.

A xenografted small-cell, undifferentiated prostate (SCUCP) cancer line, UCRU-Pr-2, was implanted at different sites within nude mice to examine the effect of local environmental factors on tumor growth and behavior. All tumors that grew were small-cell carcinomas. Fragments implanted within muscle and under the kidney capsule were locally invasive; however, tumors that grew subcutaneously or intraperitoneally showed no invasion. UCRU-Pr-2 did not grow in the spleen or the liver. No induced metastases were observed in the lung after intravenous injection. The sites of implantation did not allow the outgrowth of subpopulations as detected by the parameters used: light and electron microscopy, expression of tumor markers, levels of hormone production, and DNA flow cytometry. Electron microscopy, which showed both glandular and neuroendocrine differentiation within the same cell, does not support a dual-cell origin of SCUCP.