ROLE OF PROGESTERONE RECEPTOR RATIO IN BREAST CANCER

黄体酮是一种关键的生殖激素，结合核内黄体酮受体（pr）调节转录。PR有两种同工异构体PR- a和PR- b，它们具有非常不同的生物学效应。这两种亚型在乳腺癌中共表达。假设：黄体酮在乳腺癌中的作用受肿瘤中存在的A:B比率的影响。目的1。构建PR- a与PR- b比值可变化的乳腺癌细胞系，研究孕酮对内源性C/EBPbeta、Stat5a和bcl-xL基因随PR同型比变化的调控作用。T47D乳腺癌细胞系，其中一种PR异构体是固定的，而另一种PR异构体可以从低到高水平变化，将使用激素诱导系统来控制A:B比例。这些细胞将用于研究受两种PR差异调控的三种基因的内源性表达：受PR-B而不受PR-A调控的C/EBPbeta和Stat5a，以及受PR-A而不受PR-B调控的bcl-xL。这些研究首次尝试了解A:B比例如何调节内源性孕激素调控基因的表达。目标2。为了阐明PRA和PR- b差异调控靶基因的机制，我们克隆并鉴定了PR同工型差异调控的三个基因的启动子。C/EBPbeta、Stat5a和bcl-xL的启动子结构与PR-A或PR-B对它们的差异调控有关的假设将通过克隆这些基因的启动子来验证。启动子片段将被亚克隆到荧光素酶报告载体中，该载体将被瞬时转染到仅表达PR-A或PR-B的细胞中以研究它们的调控作用。顺式pr调控元件将通过诱变来定位。这些研究首次尝试确定启动子特异性因子是否解释PR-A与PR-B的差异转录调控。由于pr是乳腺癌的预后指标，这些研究可能需要修订临床分析，以包括两种亚型的测量。

Progesterone is a key reproductive hormone that binds to intranuclear progesterone receptors (PRs) which regulate transcription. There are two PR isoforms, PR-A and PR-B, that have very different biological effects. Both isoforms are coexpressed in breast cancers. Hypothesis:the effects of progesterone in breast cancers are influenced the A:B ratio present in the tumor. Aim 1. To construct breast cancer cell lines in which the PR-A to PR-B ratio can be varied, and to study progesterone regulation of endogenous C/EBPbeta, Stat5a and bcl-xL genes as the PR isoform ratio is varied. T47D Breast cancer cell lines in which one PR isoform is fixed, and the other can be varied from low to high levels will be created using the ecdysone inducible system to control the A:B ratio. These cells will be used to study endogenous expression of three genes differentially regulated by the two PRs: C/EBPbeta and Stat5a, which are regulated by PR-B but not PR-A, and bcl-xL, which is regulated by PR-A but not PR- B. These studies represent the first attempt to understand how the A:B ratio regulates expression of endogenous, progesterone-regulated genes. Aim 2. To elucidate the mechanisms by which PRA and PR-B differentially regulate target genes, by cloning and characterizing the promoters of three genes differentially regulated by the PR isoforms. The hypothesis that the structure of the promoters of C/EBPbeta, Stat5a and bcl-xL is responsible for their differential regulation by PR-A or PR-B will be tested by cloning the promoters of these genes. The promoter fragments will be subcloned into luciferase reporter vectors which will be transiently transfected into cells expressing only PR-A or PR-B to study their regulation. The cis-acting PR-regulated elements will be mapped by mutagenesis. These studies represent the first attempts to determine whether promoter-specific factors explain differential transcriptional regulation by PR-A vs. PR-B. Since PRs are prognostic indicators in breast cancer, these studies may require revision of clinical assays to include measurement of the two isoforms.