Characterisation of the anti-apoptotic function of P-glycoprotein and transcriptional regulation of the MDR1 gene.

P-糖蛋白抗凋亡功能的表征和 MDR1 基因的转录调控。

• 批准号: nhmrc : 350308
• 负责人: Prof Assam El-Osta
• 金额: $ 31.31万
• 依托单位: The University of Melbourne
• 依托单位国家: 澳大利亚
• 项目类别: NHMRC Project Grants
• 财政年份: 2005
• 资助国家: 澳大利亚
• 起止时间: 2005-01-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://researchdata.edu.au/characterisation-anti-apoptotic-mdr1-gene/76734
• 关键词: Characterisation; anti; apoptotic; function; glycoprotein

The ability of tumor cells to survive treatment by chemotherapy is a major obstacle in curing patients with cancer. One mechanism by which cancer cells become multidrug resistant (MDR) is their acquired expression of a protein called P-glycoprotein (P-gp) that extrudes cytotoxic drugs out of the cancer cell. We have defined a novel role for P-gp in protecting cells against death induced by non-drug stimuli, where an efflux effect of P-gp would have no obvious benefit. This broader survival effect of P-gp may be explained by its ability to regulate the activity of key enzymes (caspases) that exist within cells to induce cell suicide when appropriate. Many chemotherapeutic drugs activate caspases to kill target cells and as P-gp can inhibit caspase activation, it is therefore possible that P-gp affects the activity of anti-cancer drugs by both removing the drugs from the target cells and inhibiting the pathways through which the drugs can kill a cell. We have mutated P-gp to define the region that is necessary for its caspase regulatory function. We are now identifying the proteins that bind to this region so that we can determine how P-gp regulates caspase activation. In addition, we have defined the manner by which P-gp expression is kept low in normal cells and is upregulated following exposure of cells to chemotherapeutic drugs. The gene encoding P-gp (MDR1) is normally switched off due to the way it is packaged within a nuclear structure called chromatin. We have shown that treatment of cancer cell lines with chemotherapeutic drugs alters chromatin in such a way that the MDR1 gene is activated. We will identify the proteins and complexes involved in drug-mediated regulation of chromatin structure and determine if this phenomenon occurs within patients receiving chemotherapy. Our new findings may lead to novel treatment options for patients that have MDR cancers and may provide insight into possible new ways to inhibit the formation of P-gp-expressing MDR tumors.

肿瘤细胞在化疗治疗中存活的能力是治愈癌症患者的主要障碍。癌细胞成为多药耐药（MDR）的一种机制是它们获得性表达一种称为P-糖蛋白（P-gp）的蛋白质，该蛋白质将细胞毒性药物挤出癌细胞。我们已经确定了一种新的作用，P-gp在保护细胞免受非药物刺激诱导的死亡，其中P-gp的外排效应将没有明显的好处。P-gp的这种更广泛的存活效应可以通过其调节细胞内存在的关键酶（半胱天冬酶）的活性以在适当时诱导细胞自杀的能力来解释。许多化疗药物激活半胱天冬酶以杀死靶细胞，并且由于P-gp可以抑制半胱天冬酶激活，因此P-gp可能通过从靶细胞去除药物和抑制药物可以杀死细胞的途径来影响抗癌药物的活性。我们突变了P-gp以确定其半胱天冬酶调节功能所必需的区域。我们现在正在鉴定与该区域结合的蛋白质，以便我们能够确定P-gp如何调节半胱天冬酶激活。此外，我们已经确定了P-gp表达在正常细胞中保持低水平，并在细胞暴露于化疗药物后上调的方式。编码P-gp（MDR 1）的基因通常被关闭，这是由于它被包装在称为染色质的核结构中的方式。我们已经证明，用化疗药物治疗癌细胞系会改变染色质，从而激活MDR 1基因。我们将鉴定参与药物介导的染色质结构调节的蛋白质和复合物，并确定这种现象是否发生在接受化疗的患者中。我们的新发现可能为MDR癌症患者带来新的治疗选择，并可能为抑制表达P-gp的MDR肿瘤形成提供新的可能方法。