Androgen receptor system in androgen-independent mouse tumor developed from androgen-dependent Shionogi carcinoma 115.

An androgen-independent spindle-shaped cell tumor (NHD) formed from androgen-dependent medullary Shionogi carcinoma (SC115) in DS mice was examined. Although NHD tumors transplanted in female or male mice exhibited almost the same growth speed, the cytosol of this tumor was found to contain an androgen receptor which was similar in binding characteristics to SC115 tumor. Although significant amounts of specific binding sites for testosterone and 5 alpha-dihydrotestosterone were found in the SC115 nuclei as well as in the NHD nuclei shortly after the injection of 3H-testosterone, the androgens in the NHD nuclei disappeared rapidly. The androgen-independency of this tumor may be attributed to a rapid dissociation of the androgen-receptor complexes from NHD nuclei.