Mechanisms Regulating Reversal of Malignancy

描述（由申请人提供）：我们的长期目标是建立成功治疗方法的机制，以逆转癌前病变，鉴定损害逆转的遗传和分子事件，鉴定预测性生物标志物并将结果转化为人。该项目将利用乳腺癌和唾液腺癌的独特条件性小鼠模型来确定p53在靶向核受体维甲酸X受体α（RXR α）和过氧化物酶体增殖物激活受体γ（PPARgamma）的药理学分化治疗中的作用。癌前病变的恢复是癌症预防治疗计划的目标之一。在早期阶段中断恶性过程比治疗完全发展和可能转移的癌症更可取。该建议的中心假设是，配体诱导的上皮细胞中RXR α和PPARgamma的活化可以通过涉及蛋白磷酸酶2A（PP 2A）活性下调的再分化过程促使难治性发育异常消退。次要假设是正常p53功能有助于由RXR α和/或PPARgamma激动剂引发的再分化过程。假设：体内上皮细胞瘤前病变中RXR α和/或PPAR γ的药理学活化导致成功的疾病逆转的机制是通过细胞周期停滞和分化，所述细胞周期停滞和分化由PP 2Ac、DP-1磷酸化的下调、CDK-2的降低、p27的增加、p53活性的增加和胶原蛋白产生的减少以及细胞外基质的变化介导.在ER α阳性乳腺癌前病变中被激活的其他机制包括ER α和细胞周期蛋白D1的下调、Brca 1的上调和胶原蛋白产生的减少以及细胞外基质的变化。具体目标：1。a.测试药理学RXR α和/或PPARgamma激动剂单独或组合是否能够通过PP 2Ac表达的下调伴DP-1磷酸化的继发性获得、CDK-2的损失和p27表达的增加来再分化GRIDS小鼠中的难治性发育不良唾液组织。1. B.测试正常的p53表达水平是否有助于这些药物的成功逆转。2. a.检测药理学RXR α和/或PPARgamma激动剂单独或联合使用是否通过PP 2Ac下调、DP-1磷酸化增加、p27增加和CDK-2丢失和/或通过ER α、细胞周期蛋白D1丢失和Brca 1增加使CERM小鼠中表达ER α的导管增生和DCIS再分化。比较RXR α和/或PPARgamma激动剂与ER α拮抗剂他莫昔芬和ER α转基因条件性下调的组织学和分子学反应。2. B.测试正常p53表达是否有助于通过药理学RXR和/或PPARgamma激动剂、ER α拮抗剂他莫昔芬和/或ER α转基因的条件性下调成功逆转。2. C.检测药理学RXR α和/或PPARgamma激动剂单独或联合使用是否可预防ER α导管增生和DCIS的发生。

DESCRIPTION (provided by applicant): Our long-range goal is to establish the mechanisms underlying successful therapeutic approaches to reverse preneoplasia, identify genetic and molecular events that impair reversal, identify predictive biomarkers and translate results to people. This Project will exploit unique conditional mouse models of breast and salivary gland cancer to define the role of p53 in pharmacological differentiation therapies that target nuclear receptors Retinoid X Receptor alpha (RXRalpha) and Peroxisome proliferator-activated receptor gamma (PPARgamma). Reversal of premalignant disease is one goal of cancer prevention treatment programs. Interruption of the malignant process at an early stage is preferable to treating the fully developed and perhaps metastatic cancer. The central hypothesis of this proposal is that ligand induced activation of RXRalpha and PPARgamma in epithelial cells can impel resolution of refractory dysplasia through a re-differentiation process that involves down-regulation of Protein Phosphatase 2A (PP2A) activity. A secondary hypothesis is that normal p53 function contributes to the re-differentiation process initiated by RXRalpha and/or PPARgamma agonists. Hypothesis: The mechanism by which pharmacological activation of RXRalpha and/or PPARgamma in epithelial cell preneoplasia in vivo leads to successful disease reversal is through cell cycle arrest and differentiation mediated by down- regulation of PP2Ac, DP-1 phosphorylation, decreased CDK-2, increased p27, increased p53 activity, and decreased collagen production with changes in the extracelllalr matrix. Additional mechanisms that will be activated in ERalpha positive mammary preneoplasia include down-regulation of ERalpha and cyclin D1, up- regulation of Brca1 and decreased collagen production with changes in the extracellular matrix. Specific Aims: 1. a. Test if pharmacological RXRalpha and/or PPARgamma agonists alone or in combination are able to redifferentiate refractory dysplastic salivary tissue in GRIDS mice through down-regulation of PP2Ac expression with secondary gain of DP-1 phosphorylation, loss of CDK-2, and increased p27 expression. 1. b. Test if normal p53 expression levels contribute to successful reversal by these pharmacological agents. 2. a. Test if pharmacological RXRalpha and/or PPARgamma agonists alone or in combination redifferentiate ERalpha-expressing ductal hyperplasia and DCIS in CERM mice through down-regulation of PP2Ac, gain of DP-1 phosphorylation, increased p27 and loss of CDK-2 and/or through loss of ERalpha, cyclin D1 and increased Brca1. Compare histological and molecular responses to the RXRalpha and/or PPARgamma agonists with the ERalpha antagonist tamoxifen and conditional down-regulation of the ERalpha transgene. 2. b. Test if normal p53 expression contributes to successful reversal by pharmacological RXR and/or PPARgamma agonists, the ERalpha antagonist tamoxifen and/or conditional down-regulation of the ERalpha transgene. 2. c. Test if pharmacological RXRalpha and/or PPARgamma agonists alone or in combination prevent development of ERalpha ductal hyperplasia and DCIS.