PROGESTERONE RECEPTORS IN BREAST CANCER

乳腺癌的诱发依赖于卵巢类固醇。然而，在诊断时，2/3的肿瘤已经从类固醇激动剂控制生长转变为肽生长因子控制生长。假设：孕激素使乳腺癌因生长因子的增殖作用而起作用，然后孕激素受体（PR）下调，形成一个负反馈循环。其余三分之一的类固醇激素依赖性肿瘤对拮抗剂反应良好，但随着进展而产生耐药性。假设：对拮抗剂的获得性耐药与其激动剂作用的不适当表达有关。目的1。对激动剂的耐药性。类固醇抗性是否与生长因子信号的上调有生化联系？使用表达PR的A-或b -亚型或突变PR的稳定细胞系，我们将研究黄体酮和抗黄体酮RU486：对EGF增殖效应获得性敏感性的启动效应；MAPK和STAT信号的上调MAPK对PR的磷酸化作用，使其泛素化和下调；p21和c-fos启动子的转录协同作用。这些研究将确定PR和EGF在细胞质和细胞核中的串扰机制。目标2。获得性抗拮抗剂。混合拮抗剂的激动作用是否会因拮抗剂占据的PR中调节蛋白的募集而上调？在拮抗剂偏倚酵母双杂交筛选中分离到3个新蛋白。93号ORF有多个NR盒和至少3个TPR域。我们将克隆它，并询问它是否作为支架将PR与EGF信号分子组装在多蛋白复合物中；是一个协调节器；或将PR组装成抑制性转录复合体。另外两种新型蛋白质的作用机制也将被评估。这些研究将描述拮抗剂占据受体的功能是由三种新的受体相互作用蛋白控制的。目标3。获得性抗拮抗剂：乳腺癌。转录辅激活因子与辅抑制因子的比值是否决定了他莫昔芬的疗效？来自他莫昔芬应答或耐药患者的肿瘤将测量与治疗应答相关的共激活因子L7/SPA和SRC-1，以及共抑制因子N-CoR和SMRT的转录物表达。我们将证明SMRT抑制的机制是新颖的。其他研究针对EGF信号分子和ORF 93号。这些研究将记录共调节因子与他莫昔芬耐药之间的关系，并证明拮抗剂占据的类固醇受体不适当地募集因子。总的来说，这些研究将解释乳腺癌的激素抵抗机制。

Induction of breast cancers depends on ovarian steroids. However, at diagnosis, 2/3 of tumors have switched, from growth control by steroid agonists, to control by peptide growth factors. Hypothesis: progesterone primes breast cancers for the proliferative effects of growth factors, which then down-regulate progesterone receptors (PR) creating a negative feedback loop. The remaining 1/3 of steroid hormone-dependent tumors respond well to antagonists but acquire resistance as they progress. Hypothesis: acquired resistance to antagonists is associated with inappropriate expression of their agonist effects. Aim 1. Resistance to Agonists. Is steroid resistance biochemically linked to upregulation of growth factor signaling? Using stable cell lines expressing A- or B-isoforms of PR, or mutant PR, we will study priming effects of progesterone and the antiprogestin RU486: on acquired sensitivity to proliferative effects of EGF; on upregulation of MAPK and STAT signaling; on MAPK phosphorylation of PR which targets them for ubiquitylation and downregulation; on transcriptional synergism at p21 and c-fos promoters. These studies will define mechanisms for cross-talk between PR and EGF in the cytoplasm and nucleus. Aim 2. Acquired Resistance to Anatagonists. Are the agonist effects of mixed antagonists upregulated by recruitment of regulatory proteins to antagonist-occupied PR? Three novel proteins have been isolated in an antagonist-biased yeast two hybrid screen. ORF number 93 has multiple NR boxes and at least 3 TPR domains. We will clone it, and ask whether it acts as a scaffold to assemble PR in a multi-protein complex with EGF signaling molecules; is a coregulator; or assembles PR into a repressive transcription complex. The mechanisms of two other novel proteins will be assessed. These studies will describe the function of antagonist-occupied receptors as governed by three new receptor- interacting proteins. Aim 3. Acquired Resistance to Antagonists: Breast Cancers. Does the transcriptional coactivator to corepressor ratio determine outcome to tamoxifen? Tumors from tamoxifen responsive or resistant patients will be measured for transcript expression of the coactivators L7/SPA and SRC-1, and the corepressors N-CoR and SMRT, in relation to treatment response. We will show that mechanisms of SMRT repression are novel. Other studies address EGF signaling molecules and ORF number 93. These studies will document the relationships between coregulators and tamoxifen resistance, and demonstrate that antagonist-occupied steroid receptors recruit factors inappropriately. Overall, these studies will explain hormone-resistance mechanisms in breast cancers.