An androgen-dependent pilosebaceous tumor spontaneously developed in the japanese house musk shrew Suncus murinus

Abstract

Following administration of [ 3H]testosterone to castrated male Japanese house musk shrews ( Suncus murinus), radioactive metabolites were detected in sidegland nuclei and the major one of them was dihydrotestosterone (DHT). The androgen binding capacity of the cytoplasmic fraction of sideglands was measured in vitro by the use of [ 3H]R1881 as a ligand. The binding showed a high affinity for R1881 ( K d = 6.2 × 10 −10 M) and a low capacity ( B max = 22 fmol/mg protein). p]Sucrose density gradient centrifugation brought about a peak of [ 3H]R1881 in the 7S region in low ionic strength buffer. Their characteristics as described above are consistent with those of other androgen target organs. A cutaneous pilosebaceous tumor, which spontaneously developed on the sidegland of old male S. murinus, was transplanted to nude athymic mice. It grew in males only and failed to grow in females and castrated males. A specific androgen binding was found in this tumor ( K d = 7.8 × 10 −10M, B max = 100 fmol/mg protein). Therefore, this transplantable pilosebaceous tumor is androgen-dependent and can be utilized as a new suitable model in the study of the mechanism of androgen on tumor development.