Serial transplantation to nude mice of an androgen-dependent pilosebaceous tumor developed in Suncus murinus.

The pilosebaceous tumor spontaneously developed on the sidegland of an old male Suncus murinus was serially transplanted into male nude athymic (BALB/c-nu/nu) mice. By the 18th generation, tumor growth occurred in about 70% of them. The transplantability of the tumor maintained in these male mice to female or castrated male nude mice was less than 35%. The histological features of the tumor did not differ by the hormonal status of hosts. Tumor growth started later and was slower in females than in males. This androgen dependency seems to be restricted to an initial period of growth, since the transplantability to males was decreased by castration within a week after grafting. The tumors grown in males possessed both cytoplasmic and nuclear androgen receptors and those in females cytoplasmic androgen receptor only. The latter tumors were found androgen-sensitive, because treatment with testosterone propionate significantly increased tumor size. In addition, after [3H]-testosterone administration, bound radioactivity was detected in the nuclear fraction from female as well as male hosts. Although the mechanism responsible for the development of these androgen-independent sensitive cells is unknown, the variance in transplantability to female hosts suggests that the original tumor was composed of androgen-dependent and androgen-independent cells.