Marcelli M, Haidacher S J, Plymate S R, Birnbaum R S
Department of Medicine, Baylor College of Medicine, Houston, Texas.
Endocrinology. 1995 Mar;136(3):1040-8. doi: 10.1210/endo.136.3.7532576.
The network of androgen-dependent growth factors regulating the growth and function of normal or neoplastic prostate epithelium is largely unknown. To facilitate studies directed at investigating this issue, androgen receptor-negative (AR-) PC3 prostate carcinoma cells were stably transfected with the expression plasmid CMV3 containing a constitutively active AR construct that is truncated at its hormone-binding domain (CMV-ARCA). The major characteristic of the resulting cell line (PC3-ARCA) was a growth rate approximately 35% slower than that of a control mock-transfected cell line (PC3-Neo). Of the several growth factors known to be present in the prostate, the current studies focused on the insulin-like growth factor (IGF) axis, specifically the IGF-binding proteins (IGFBPs), several of which are known to be abnormally produced by prostate cancer. Northern analysis showed that IGFBP-1 and -5 are not expressed by PC3-ARCA and -Neo cells. Western ligand and immunoblot analysis of medium conditioned by PC3-Neo and PC3-ARCA cells revealed that equal amounts of IGFBP-2, -4, and -6 were secreted. In contrast, IGFBP-3 was undetectable in the conditioned medium of PC3-ARCA cells, but normally produced by the AR- cell line PC3-Neo. IGFBP-3 disappearance from the conditioned medium of PC3-ARCA cells was transcriptionally regulated, as a marked decrement in IGFBP-3 messenger RNA was detected by S1 protection analysis. We investigated the responses of these cells to exogenously added IGF-I, IGF-II, or IGFBP-3. IGF-I and IGF-II stimulated the proliferation of PC3-ARCA cells, but not of PC3-Neo cells. IGFBP-3 had no effect when given alone. When IGFBP-3 was administered together with IGF-I or IGF-II, it further increased the mitogenic response observed in PC3-ARCA cells, but no effect on PC3-Neo cells was observed. In conclusion, our studies suggest that the presence of an active AR modulates the proliferation of transfected PC3 prostate cancer cells, and that this phenomenon occurs at least in part through the regulation of IGFBP-3 production.
调节正常或肿瘤性前列腺上皮细胞生长和功能的雄激素依赖性生长因子网络在很大程度上尚不清楚。为便于开展针对该问题的研究，用含有在激素结合结构域截短的组成型活性雄激素受体（AR）构建体的表达质粒CMV3稳定转染雄激素受体阴性（AR-）的PC3前列腺癌细胞。所得细胞系（PC3-ARCA）的主要特征是生长速率比对照空载体转染细胞系（PC3-Neo）慢约35%。在已知存在于前列腺中的几种生长因子中，当前研究聚焦于胰岛素样生长因子（IGF）轴，特别是IGF结合蛋白（IGFBP），其中几种已知由前列腺癌异常产生。Northern分析表明PC3-ARCA和PC3-Neo细胞不表达IGFBP-1和-5。对PC3-Neo和PC3-ARCA细胞条件培养基进行的Western配体和免疫印迹分析显示，分泌的IGFBP-2、-4和-6量相等。相反，在PC3-ARCA细胞的条件培养基中未检测到IGFBP-3，但AR-细胞系PC3-Neo正常产生该蛋白。PC3-ARCA细胞条件培养基中IGFBP-3的消失受转录调控，因为通过S1保护分析检测到IGFBP-3信使核糖核酸显著减少。我们研究了这些细胞对外源添加的IGF-I、IGF-II或IGFBP-3的反应。IGF-I和IGF-II刺激PC3-ARCA细胞增殖，但不刺激PC3-Neo细胞增殖。单独给予IGFBP-3无作用。当IGFBP-3与IGF-I或IGF-II一起给予时，它进一步增强了在PC3-ARCA细胞中观察到的促有丝分裂反应，但对PC3-Neo细胞无作用。总之，我们的研究表明活性AR的存在调节转染的PC3前列腺癌细胞的增殖，并且这种现象至少部分通过调节IGFBP-3的产生而发生。
