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逆转瘤前病变的治疗方法的机制，确定损害逆转的遗传和分子事件，确定预测性生物标志物并将结果转化给人们。该项目将利用独特的条件小鼠乳腺癌和唾液腺癌模型来确定p53在针对核受体类视黄醇X受体α (rxrα)和过氧化物酶体增殖物激活受体γ (PPARgamma)的药物分化治疗中的作用。逆转癌前病变是癌症预防治疗项目的目标之一。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rxrα和pppargamma的激活可以通过下调蛋白磷酸酶2A （PP2A）活性的再分化过程来促进难治性发育不良的解决。第二个假设是正常的p53功能有助于rxrα和/或PPARgamma激动剂启动的再分化过程。假设：体内上皮细胞瘤前病变中rxrα和/或pppargamma的药理激活导致疾病成功逆转的机制是通过细胞周期阻滞和分化介导的PP2Ac下调、DP-1磷酸化、CDK-2降低、p27升高、p53活性升高、细胞外基质改变导致胶原生成减少。在erα阳性的乳腺瘤前病变中激活的其他机制包括erα和cyclin D1的下调，Brca1的上调以及细胞外基质变化导致的胶原生成减少。具体目标：1；a.测试药物RXRalpha和/或pppargamma激动剂单独或联合使用是否能够通过下调PP2Ac表达、DP-1磷酸化继发增加、CDK-2缺失和p27表达增加来重新分化栅格小鼠难治性发育不良的唾液组织。1. b.检测正常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rxrα和/或pppargamma激动剂单独或联合使用是否通过下调PP2Ac、DP-1磷酸化增加、p27增加和CDK-2缺失和/或通过erα、cyclin D1缺失和Brca1增加，在CERM小鼠中重新分化表达erα的导管增生和DCIS。比较rxrα和/或PPARgamma激动剂与er α拮抗剂他莫昔芬的组织学和分子反应以及er α转基因的条件下调。2. b.检测正常p53表达是否有助于RXR和/或PPARgamma激动剂、erα拮抗剂他莫昔芬和/或erα转基因的条件下调成功逆转。2. c.检测RXRalpha和/或PPARgamma激动剂单独或联合使用是否能预防er - alpha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.