MOLECULAR DETERMINANTS OF DRUG SENSITIVITY

药物敏感性的分子决定因素

• 批准号: 6376898
• 负责人: WILLIAM N. HAIT
• 金额: $ 15.86万
• 依托单位: UNIV OF MED/DENT NJ-R W JOHNSON MED SCH
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-12 至 2004-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6376898
• 关键词: DNA damage; antimitotics; antineoplastics; apoptosis; cell cycle; chemosensitizing agent; combination cancer therapy; fibroblasts; gene expression; gene mutation; immunofluorescence technique; microtubule associated protein; mutant; neoplasm /cancer chemotherapy; p53 gene /protein; paclitaxel; pharmacokinetics; polymerization; protein structure function; tissue /cell culture; transfection; vinca alkaloids

The treatment of cancer patients with chemotherapy is often empirical. Even the most active drugs produce meaningful responses in the minority of patients. As a result, many patients are exposed to and suffer the side effects of toxic medications without reaping the benefits. For example, taxanes, such as paclitaxel and docetaxel, and vinca alkaloids, such as vinorelbine, and vinblastine, are amongst the most active drugs in the treatment of common malignancies including breast, lung, and prostate. Yet, less than 50 percent of patients respond to these individual agents. Despite this, clinicians have no way of predicting who will respond and who will not. Mutations in p53 occur in approximately 50 percent of human cancers. Recent studies indicate that p53 mutations affect the sensitivity to cancer chemotherapeutic drugs. In studying the mechanism(s) underlying this observation, we found that increased expression of microtubule associated protein 4 (MAP4), which occurs when p53 is transcriptionally silent, is associated with increased sensitivity to paclitaxel and decreased sensitivity to vinca alkaloids. Using murine fibroblasts transfected with MAP4, we demonstrated that these changes in drug sensitivity were reproduced by overexpression of the MAP4 protein. MAP4 overexpression resulted in alterations in drug-induced apoptosis and cell-cycle arrest. Immunofluorescent staining of the microtubule network revealed that cells with increased MAP4 protein expression contained greater polymerized microtubules and bound more fluoresceinated paclitaxel than controls. Since MAP4 catalyzes and stabilizes the polymerization of microtubules, overexpression of this gene provides a credible mechanism to explain the sensitivity to microtubule-active drugs in the presence of mutant p53. Therefore, we propose to study the implications of these observations by analyzing the effects of p53 function on MAP4 overexpression and drug sensitivity in human cancer cell lines and following wild type p53 induction by DNA damage. We will capitalize on our findings to design more rationale uses of antimitotic drugs in combination with DNA damaging agents.

用化疗治疗癌症患者通常是经验性的。 即使是最有效的药物也会在少数患者中产生有意义的反应。 因此，许多患者暴露于并遭受有毒药物的副作用，而没有获得益处。 例如，紫杉烷类（如紫杉醇和多西他赛）和长春花生物碱类（如长春瑞滨和长春碱）是治疗常见恶性肿瘤（包括乳腺癌、肺癌和前列腺癌）中最有活性的药物。 然而，只有不到50%的患者对这些药物有反应。 尽管如此，临床医生无法预测谁会做出反应，谁不会。p53突变发生在大约50%的人类癌症中。 最近的研究表明，p53突变影响癌症化疗药物的敏感性。 在研究这一观察结果背后的机制时，我们发现当p53转录沉默时发生的微管相关蛋白4（MAP 4）的表达增加与对紫杉醇的敏感性增加和对长春花生物碱的敏感性降低有关。 使用MAP4转染的小鼠成纤维细胞，我们证明了这些药物敏感性的变化是通过MAP4蛋白的过表达来再现的。 MAP4过表达导致药物诱导的细胞凋亡和细胞周期停滞的改变。 微管网络的免疫荧光染色显示，与对照组相比，MAP4蛋白表达增加的细胞含有更多的聚合微管，并结合更多的荧光素化紫杉醇。 由于MAP4催化和稳定微管的聚合，该基因的过表达提供了一个可信的机制来解释突变型p53存在下对微管活性药物的敏感性。 因此，我们建议通过分析p53功能对人类癌细胞系中MAP4过表达和药物敏感性的影响以及野生型p53诱导DNA损伤来研究这些观察结果的意义。 我们将利用我们的研究结果，设计更多的合理使用抗有丝分裂药物与DNA损伤剂的组合。