Novel CTD inhibitors with synthetic lethality to oncogenic Ras for cancer therapy

新型 CTD 抑制剂对致癌 Ras 具有合成杀伤力，用于癌症治疗

• 批准号: 7779354
• 负责人: BINGLIANG FANG
• 金额: $ 31.06万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7779354
• 关键词: Antineoplastic Agents; Apoptosis; Breast; C-terminal; CDK9 Protein Kinase; Cancer cell line; Categories; Cell Line; Cells; Clinical Treatment; Clinical Trials; Colon; Complex; Cyclin-Dependent Kinases; Data; Development; Developmental Therapeutics Program; Drug Kinetics; Epithelial Cells; Evaluation; Future; Gene Mutation; Genetic Transcription; Genus Cola; Goals; Growth; Human; In Vitro; Induction of Apoptosis; K-ras Gene; Lead; Lung; Lung Neoplasms; Maintenance; Malignant Neoplasms; Malignant neoplasm of lung; Molecular; Molecular Analysis; Mutation; National Cancer Institute; New Agents; Normal Cell; Nude Mice; Oncogenes; Oncogenic; Ovarian; Ovary; Pathway interactions; Personal Communication; Phenotype; Phosphorylation; Play; Predisposition; RAS genes; RNA; RNA Polymerase II; RNA Splicing; RNA polymerase II largest subunit; Renal carcinoma; Reporting; Role; Safety; Screening procedure; Small Interfering RNA; Solid; Testing; Therapeutic Agents; Toxic effect; Yeasts; analog; anti-cancer therapeutic; anticancer activity; anticancer treatment; antitumor agent; cancer cell; cancer therapy; cell transformation; cyclin T1; cytotoxic; flavopiridol; in vitro activity; in vivo; inhibitor/antagonist; killings; mutant; novel; novel therapeutics; pre-clinical; preclinical study; prevent; protein kinase C iota; prototype; public health relevance; ras Proteins; research clinical testing; small molecule libraries; tumor; tumor xenograft; tumorigenic

DESCRIPTION (provided by applicant): The oncogenic Ras proteins play critical roles in the development and maintenance of cancer phenotypes and serve as important targets for anticancer treatment. However, oncogenic Ras-targeted therapeutic agents are not yet available. Therefore, it is urgent to develop anticancer agents that can effectively eliminate Ras-mutant cancer cells. We hypothesize that agents that induce synthetic lethality in cancer cells expressing oncogenic Ras genes but not in normal isogenic cells will be valuable prototypes for developing Ras-targeted anticancer therapeutics. In searching for such agents, we screened a chemical library and identified a compound (designated oncrasin-1) that kills immortalized and tumorigenic human ovarian epithelial cells expressing oncogenic K-Ras but not their isogenic normal counterparts. Oncrasin-1 can effectively kill various lung cancer cells with K-Ras mutations. The cytotoxic effects correlated with apoptosis induction by the compounds and could be blocked by K-Ras siRNA or protein kinase C iota (PKCiota) siRNA, suggesting that Ras and/or PKCiota activities are required for oncrasin-induced apoptosis. Treatment of sensitive cancer cells with oncrasin-1, -60, or -231 led to suppression of the phosphorylation of the C-terminal domain (CTD) of the largest subunit of RNA polymerase II, whish is consistent with previous reports that the continuous activity of RNA polymerase II is required to prevent oncogene-induced apoptosis in transformed cells and that mutations compromising CTD function is synthetically lethal with elevated levels of Ras activity in yeast. Treatment with oncrasin-1 also led to co-aggregation of PKCiota and splicing factors in megaspliceosomes and to disruption of the interaction between PKCiota and CDK9/cyclin T1 complex, which phosphorylates the CTD. Thus, we hypothesized that oncrasin compounds are a novel class of CTD inhibitors with selective anticancer activity. The in vivo administration of oncrasin-1 suppressed the growth of human lung tumor xenografts by >70% and prolonged the survival of tumor-bearing nude mice without causing detectable toxicity. Testing some of those analogues on NCI-60 cell lines showed that oncrasins are active against several cell lines derived from lung, colon, breast, ovary, and kidney cancers and oncrasin-60 lies outside the category of adequately studied classes of antitumor agents, indicating its novel anticancer mechanisms. Thus, oncrasin compounds are potentially a novel class of CTD inhibitors that are synthetically lethal to cancers with increased Ras/PKCiota activity. However, in vivo evaluation of the pharmacokinetics, antitumor efficacy, and safety of oncrasin compounds is necessary before they can be evaluated clinically. The goal of this proposal is to determine anti- lung cancer activity of the most active analogues by evaluating their in vitro activities in several lung cancer cell lines with or without Ras gene mutations, their pharmacokinetics, and their in vivo activity and toxicity. The proposed studies will provide solid preclinical data for possible clinical evaluation of oncrasin compounds and may lead to the development of new therapeutic agents that are useful for the treatment of lung cancers. PUBLIC HEALTH RELEVANCE: We have identified a group of new agents that are selectively toxic to cancer cells with increased Ras activity but not to normal cells. The molecular characterization revealed those compounds inhibit the phosphorylation and function of C-terminal domain of the largest subunit of RNA polymerase II. The goal of this proposal is to perform pre-clinical studies on their antitumor activities in lung cancer cells in vitro and in vivo that are required for future clinical trials.

描述（申请人提供）：致癌Ras蛋白在癌症表型的发展和维持中起着关键作用，是抗癌治疗的重要靶点。然而，目前还没有针对肿瘤的ras靶向治疗药物。因此，开发能够有效消灭ras突变癌细胞的抗癌药物迫在眉睫。我们假设，在表达致癌Ras基因的癌细胞中诱导合成致死性的药物，而不是在正常等基因细胞中诱导合成致死性的药物，将是开发Ras靶向抗癌治疗药物的有价值的原型。在寻找这类药物的过程中，我们筛选了一个化学文库，并确定了一种化合物（命名为oncrasin-1），它可以杀死表达致癌K-Ras的永生化和致瘤性人类卵巢上皮细胞，而不是它们的等基因正常对应物。Oncrasin-1能有效杀伤多种K-Ras突变的肺癌细胞。细胞毒性作用与化合物诱导的细胞凋亡相关，可被K-Ras siRNA或PKCiota siRNA阻断，表明Ras和/或PKCiota活性是oncrasin诱导的细胞凋亡所必需的。用oncrasin-1、-60或-231治疗敏感癌细胞可抑制RNA聚合酶II最大亚基c末端结构域（CTD）的磷酸化，这与之前的报道一致，即RNA聚合酶II的持续活性是防止转化细胞中癌基因诱导的凋亡所必需的，并且在酵母中，随着Ras活性水平的升高，损害CTD功能的突变是合成致死的。用oncrasin-1处理也导致PKCiota和剪接因子在大粒粒体中共同聚集，并破坏PKCiota和CDK9/cyclin T1复合物之间的相互作用，从而磷酸化CTD。因此，我们假设oncrasin化合物是一类具有选择性抗癌活性的新型CTD抑制剂。体内给药oncrasin-1可抑制人肺癌异种移植物生长约70%，延长荷瘤裸鼠的生存期，且无明显毒性。在NCI-60细胞系上测试这些类似物表明，oncrasins对来自肺癌、结肠癌、乳腺癌、卵巢癌和肾癌的几种细胞系有活性，而oncrasins -60不在充分研究的抗肿瘤药物类别中，表明其具有新的抗癌机制。因此，oncrasin化合物可能是一类新的CTD抑制剂，对Ras/PKCiota活性增加的癌症具有合成致死性。然而，在进行临床评价之前，有必要对oncrasin化合物的体内药代动力学、抗肿瘤功效和安全性进行评估。本研究的目的是通过评估其在几种具有或不具有Ras基因突变的肺癌细胞系中的体外活性、药代动力学以及体内活性和毒性来确定最具活性的类似物的抗肺癌活性。拟议的研究将为致癌素化合物的临床评估提供可靠的临床前数据，并可能导致开发新的治疗药物，用于治疗肺癌。