Paliouras Miltiadis, Diamandis Eleftherios P
Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, 600 University Ave., M5G 1X5 Toronto, ON, Canada.
Breast Cancer Res Treat. 2007 Mar;102(1):7-18. doi: 10.1007/s10549-006-9312-y. Epub 2006 Aug 8.
The regulation of gene expression by steroid hormones plays an important role in the normal development and function of many organs, as well in the pathogenesis of endocrine-related cancers. Previous experiments have shown that many kallikrein genes are under steroid hormone regulation in breast cancer cell lines. We here examine the coordinated expression of multiple kallikrein genes in several breast cancer cell lines after steroid hormone stimulation. Breast cancer cell lines were treated with various steroid hormones and kallikrein (KLK/hK) expression of hK3 (prostate-specific antigen, PSA), hK5, hK6, hK7, hK8, hK10, hK11, hK13, and hK14 was analyzed at the RNA level via RT-PCR and at the protein level by immunofluorometric ELISA assays. We identified several distinct hK hormone-dependent and hormone-independent expression patterns. Hormone-specific modulation of expression was seen for several kallikreins in BT-474, MCF-7, and T-47D cell lines. hK6 was specifically up-regulated upon estradiol treatment in all three cell lines whereas PSA expression was induced by dihydrotestosterone (DHT) and norgestrel stimulation in BT-474 and T-47D. hK10, hK11, hK13, and hK14 were specifically up-regulated by DHT in T-47D and by estradiol in BT-474 cells. Bioinformatic analysis of upstream proximal promoter sequences for these hKs did not identify any recognizable hormone-response elements (HREs), suggesting that the coordinated activation of these four hKs represents a unique expression "cassette", utilizing a common hormone-dependent mechanism. We conclude that groups of human hKs are coordinately expressed in a steroid hormone-dependent manner. Our data supports clinical observations linking expression of multiple hKs with breast cancer prognosis.
类固醇激素对基因表达的调控在许多器官的正常发育和功能中起着重要作用，在内分泌相关癌症的发病机制中也同样如此。先前的实验表明，许多激肽释放酶基因在乳腺癌细胞系中受类固醇激素调控。我们在此研究类固醇激素刺激后几种乳腺癌细胞系中多个激肽释放酶基因的协同表达。用各种类固醇激素处理乳腺癌细胞系，并通过逆转录聚合酶链反应（RT-PCR）在RNA水平以及通过免疫荧光酶联免疫吸附测定法在蛋白质水平分析人激肽释放酶3（前列腺特异性抗原，PSA）、hK5、hK6、hK7、hK8、hK10、hK11、hK13和hK14的激肽释放酶（KLK/hK）表达。我们确定了几种不同的hK激素依赖性和激素非依赖性表达模式。在BT-474、MCF-7和T-47D细胞系中，几种激肽释放酶出现了激素特异性的表达调节。在所有这三种细胞系中，雌二醇处理后hK6均特异性上调，而在BT-474和T-47D中，双氢睾酮（DHT）和炔诺孕酮刺激诱导了PSA表达。在T-47D中，DHT特异性上调了hK10、hK11、hK13和hK14，在BT-474细胞中，雌二醇特异性上调了它们。对这些hK的上游近端启动子序列进行生物信息学分析未发现任何可识别的激素反应元件（HRE），这表明这四种hK的协同激活代表了一种独特的表达“盒”，利用了一种共同的激素依赖性机制。我们得出结论，人hK组以类固醇激素依赖性方式协同表达。我们的数据支持将多种hK的表达与乳腺癌预后相关联的临床观察结果。
