MOLECULAR DETERMINANTS OF DRUG SENSITIVITY

药物敏感性的分子决定因素

• 批准号: 6174063
• 负责人: WILLIAM N. HAIT
• 金额: $ 15.46万
• 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/6174063
• 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.

癌症患者的化疗治疗通常是经验性的。 即使是最活跃的药物也会在少数患者中产生有意义的反应。 结果，许多患者接触有毒药物并遭受副作用，却没有获得好处。 例如，紫杉烷类（例如紫杉醇和多西紫杉醇）和长春花生物碱（例如长春瑞滨和长春花碱）是治疗乳腺癌、肺癌和前列腺癌等常见恶性肿瘤最有效的药物。 然而，只有不到 50% 的患者对这些单独的药物有反应。 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 突变会影响对癌症化疗药物的敏感性。 在研究这一观察结果的机制时，我们发现，当 p53 转录沉默时，微管相关蛋白 4 (MAP4) 表达增加，与紫杉醇敏感性增加和长春花生物碱敏感性降低相关。 使用转染 MAP4 的小鼠成纤维细胞，我们证明药物敏感性的这些变化是通过 MAP4 蛋白的过度表达而重现的。 MAP4 过度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紫杉醇。 由于 MAP4 催化并稳定微管的聚合，因此该基因的过度表达提供了可靠的机制来解释突变 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通过 DNA 损伤诱导野生型 p53 来研究这些观察结果的含义。 我们将利用我们的发现来设计抗有丝分裂药物与 DNA 损伤剂联合使用的更合理用途。