Kemp C J, Leary C N, Drinkwater N R
McArdle Laboratory for Cancer Research, University of Wisconsin, Madison 53706.
Proc Natl Acad Sci U S A. 1989 Oct;86(19):7505-9. doi: 10.1073/pnas.86.19.7505.
Tfm (testicular feminization) mutant mice lack functional androgen receptors. By studying liver tumor development in Tfm mice, we have shown that the greater susceptibility of male mice relative to female mice for liver tumor induction by N,N-diethylnitrosamine is androgen receptor-dependent. C57BL/6J normal and Tfm mutant mice were injected at 12 days of age with N,N-diethylnitrosamine (0.2 mumol/g, i.p.), and liver tumors were enumerated in 50-week-old animals. Normal males averaged 20 liver tumors per animal; Tfm males, 0.7; normal females, 0.6; and Tfm/+ heterozygous females, 1.5. The androgen receptor gene and the Tfm mutation are X chromosome linked. Because of random X chromosome inactivation, hepatocytes from Tfm/+ heterozygous female mice are mosaic with respect to the expression of mutant or wild-type receptors. To determine if testosterone acts directly as a liver tumor promoter, through the androgen receptor in preneoplastic hepatocytes, or by an indirect mechanism, we chronically treated these mosaic female mice with testosterone and measured the androgen receptor content of the resulting tumors. B6C3F1 Tfm/+ mosaic and +/+ wild-type female mice were injected i.p. at 12 days of age with N,N-diethylnitrosamine (0.1 mumol/g) and ovariectomized at 8 weeks of age. Half of the mice of each group subsequently received biweekly s.c. injections of testosterone (0.15 mg per mouse) for 30 weeks. Tumor multiplicity was the same for wild-type and Tfm/+ mosaic females treated with testosterone (31-32 tumors per animal at 38 weeks of age) and was increased relative to females not treated with testosterone (13-17 tumors per animal at 50 weeks of age). Testosterone treatment did not significantly increase the percentage of androgen receptor-positive tumors in Tfm/+ mosaic females: 58% of the tumors from Tfm/+ mosaic females treated with testosterone were receptor positive compared to 48% in Tfm/+ females not treated with testosterone and 92% in wild-type females treated with testosterone. Finally, the number of androgen receptors in the majority of liver tumors examined was greatly decreased relative to the surrounding normal liver tissue. We conclude that liver tumor promotion by testosterone requires a functional androgen receptor in the intact animal. However, this promotion is not cell autonomous; that is, the response of the preneoplastic hepatocyte is not dependent on the expression of functional receptor in the target cell.
睾丸雌性化（Tfm）突变小鼠缺乏功能性雄激素受体。通过研究Tfm小鼠的肝肿瘤发展，我们发现雄性小鼠相对于雌性小鼠对N，N - 二乙基亚硝胺诱导肝肿瘤的易感性更高是雄激素受体依赖性的。在12日龄时给C57BL / 6J正常和Tfm突变小鼠腹腔注射N，N - 二乙基亚硝胺（0.2μmol/g），并在50周龄动物中统计肝肿瘤数量。正常雄性平均每只动物有20个肝肿瘤；Tfm雄性为0.7个；正常雌性为0.6个；Tfm / +杂合雌性为1.5个。雄激素受体基因和Tfm突变与X染色体连锁。由于随机的X染色体失活，Tfm / +杂合雌性小鼠的肝细胞在突变型或野生型受体的表达方面是嵌合体。为了确定睾酮是否直接作为肝肿瘤促进剂，通过癌前肝细胞中的雄激素受体起作用，还是通过间接机制起作用，我们用睾酮长期处理这些嵌合雌性小鼠，并测量所产生肿瘤中的雄激素受体含量。在12日龄时给B6C3F1 Tfm / +嵌合和 + / +野生型雌性小鼠腹腔注射N，N - 二乙基亚硝胺（0.1μmol/g），并在8周龄时进行卵巢切除。每组一半的小鼠随后每两周皮下注射一次睾酮（每只小鼠0.15mg），持续30周。用睾酮处理的野生型和Tfm / +嵌合雌性的肿瘤 multiplicity相同（38周龄时每只动物31 - 32个肿瘤），并且相对于未用睾酮处理的雌性（50周龄时每只动物13 - 17个肿瘤）有所增加。睾酮处理并未显著增加Tfm / +嵌合雌性中雄激素受体阳性肿瘤的百分比：用睾酮处理的Tfm / +嵌合雌性的肿瘤中有58％受体阳性，相比之下，未用睾酮处理的Tfm / +雌性中为48％，用睾酮处理的野生型雌性中为92％。最后，与周围正常肝组织相比，大多数检查的肝肿瘤中的雄激素受体数量大大减少。我们得出结论，睾酮对肝肿瘤的促进作用在完整动物中需要功能性雄激素受体。然而，这种促进不是细胞自主的；也就是说，癌前肝细胞的反应不依赖于靶细胞中功能性受体的表达。
