ACTIVITY OF MULTI DRUG RESISTANCE P-GLYCOPROTEINS

多重耐药P-糖蛋白的活性

• 批准号: 2750289
• 负责人: KATHRYN L COULTER
• 金额: $ 3.05万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/2750289
• 关键词: CHO cells; P glycoprotein; cell growth regulation; cholesterol; cytotoxicity; enzyme activity; enzyme induction /repression; enzyme mechanism; isozymes; lipid metabolism; multidrug resistance; phosphorylation; protein kinase C; steroid metabolism; transfection

Multiple drug resistance of tumor cells is a major obstacle in the successful treatment of cancer by chemotherapy. Multiple drug resistance frequently results from amplification and overexpression of a family of proteins termed multiple drug resistance (MDR) P-glycoproteins. The MDR proteins have multiple sites for phosphorylation by protein kinase C (PKC), and a number of recent observations suggest that MDR may be directly activated by PKC phosphorylation. First, expression of specific PKC isoenzymes is increased in multiple drug resistant cell lines in comparison with the drug-sensitive parent cell lines. Second, treatment of MDR cell lines with PKC activators enhances drug resistance, while treatment with PKC inhibitors reverses the MDR phenotype. Finally, transfection of some PKC isoenzymes enhances the MDR phenotype. In addition, the proteins coded by all of the MDR cDNA's isolated to date have multiple potential PKC phosphorylation sites, indicating that PKC may play a direct role in the phosphorylation of MDR. Evidence from our lab demonstrates that MDR P-glycoproteins play an important role in cholesterol biosynthesis and esterification, possibly by transporting cholesterol and cholesterol precursors between membranes within the cell. This finding suggests that PKC regulation of MDR activity may play a normal physiologic role in cholesterol metabolism. The current proposal describes experiments designed to test the hypothesis that specific PKC isoenzymes directly regulate MDR activity by phosphorylation. and that this regulation has consequential effects on cellular cholesterol metabolism. To test this hypothesis, I will assess the ability of each of ten different PKC isoenzymes (alpha, BetaI, BetaII, gamma, delta, epsilon, eta, theta, mu, and zeta) to alter MDR activity when overexpressed in CHO cells; I will assay changes in drug accumulation, drug-induced ATPase activity, and cell growth in the presence of cytotoxic MDR substrate drugs.

Multiple drug resistance of tumor cells is a major obstacle in the 通过化疗成功治疗癌症。多重耐药 frequently results from amplification and overexpression of a family of proteins termed multiple drug resistance (MDR) P-glycoproteins.多重耐药性 蛋白质具有多个被蛋白激酶 C 磷酸化的位点 （PKC），最近的一些观察结果表明 MDR 可能是 直接被 PKC 磷酸化激活。一、具体表达 PKC isoenzymes is increased in multiple drug resistant cell lines in 与药物敏感的亲代细胞系进行比较。二、治疗 of MDR cell lines with PKC activators enhances drug resistance, while treatment with PKC inhibitors reverses the MDR phenotype.最后， transfection of some PKC isoenzymes enhances the MDR phenotype.在 此外，迄今为止分离出的所有 MDR cDNA 编码的蛋白质 have multiple potential PKC phosphorylation sites, indicating that PKC may play a direct role in the phosphorylation of MDR. Evidence from our lab demonstrates that MDR P-glycoproteins play an 可能在胆固醇生物合成和酯化中起重要作用 通过在膜之间运输胆固醇和胆固醇前体 细胞内。这一发现表明 PKC 对 MDR 的调节 活动可能在胆固醇代谢中发挥正常的生理作用。 当前的提案描述了旨在测试的实验 特定 PKC 同工酶直接调节 MDR 活性的假设 通过磷酸化。 and that this regulation has consequential effects 对细胞胆固醇代谢的影响。 为了检验这个假设，我将评估十个人中每人的能力 不同的 PKC 同工酶（α、BetaI、BetaII、gamma、delta、epsilon、 eta, theta, mu, and zeta) to alter MDR activity when overexpressed in CHO 细胞；我将检测药物蓄积、药物诱导的 ATPase 的变化 activity, and cell growth in the presence of cytotoxic MDR substrate 药物。