A Role of Bit1 in the Apoptosis Resistance, Anoikis Insensitvity, and Chemoresist

Bit1 在细胞凋亡抵抗、失巢凋亡不敏感性和化疗抵抗中的作用

• 批准号: 8224157
• 负责人: Hector Ramos Biliran
• 金额: $ 36.29万
• 依托单位: XAVIER UNIVERSITY OF LOUISIANA
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-02-28 至 2015-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8224157
• 关键词: Address; Anchorage-Independent Growth; Anoikis; Apoptosis; Apoptotic; Attenuated; Bypass; Cancer Biology; Cancer cell line; Caspase; Cell Death; Cell Death Induction; Cell-Matrix Junction; Cells; DNA Damage; Data; Defect; Disabled Persons; Disease; Distant; Down-Regulation; Ectopic Expression; Etoposide; Exhibits; Figs - dietary; Genetic Transcription; Goals; Heat-Shock Proteins 70; Human; Induction of Apoptosis; Integrins; Lung; Lung Neoplasms; Malignant - descriptor; Malignant Neoplasms; Malignant neoplasm of lung; Mediating; Mitochondria; Molecular; Molecular Analysis; Neoplasm Metastasis; Non-Small-Cell Lung Carcinoma; Oncogenes; Organ; Outcome Study; Pathway interactions; Pharmaceutical Preparations; Phenotype; Predisposition; Principal Investigator; Proteins; Publishing; Radiation; Regulation; Relative (related person); Research; Resistance; Role; Signal Pathway; Signal Transduction; Small Interfering RNA; Stimulus; Structure of parenchyma of lung; Testing; Therapeutic; Tissues; apoptosis inducing factor; base; cancer cell; cancer therapy; chemotherapeutic agent; chemotherapy; combat; inhibitor/antagonist; insight; mortality; new therapeutic target; novel; outcome forecast; overexpression; programs; response; restoration; small hairpin RNA; tool; undergraduate student

DESCRIPTION (provided by applicant): Non-small cell lung cancer (NSCLC) is a highly aggressive form of malignancy that is associated with metastasis and poor response to chemotherapy. Non-small cell lung cancer cells exhibit high resistance to undergo apoptosis, at least in part due to a disabled apoptotic machinery. In particular, partial defects in the caspase-dependent pathway in NSCLC cells conferred resistance to apoptosis induced by DNA-damaging agents such as etoposide or 3-radiation (9,14). Hence, a major therapeutic avenue in combating the aggressiveness and chemotherapy resistance of NSCLC is through effective induction of apoptosis by the alternative caspase-independent cell death pathway. The goal of this project is to address the critical barrier to NSCLC treatment by obtaining the information needed to understand the role of the novel caspase- independent anoikis effector, Bcl2-inhibitor of transcription (Bit1), in the apoptosis resistance and malignant transformation of NSCLC cells. Several observations indicate the nonfunctionality of the Bit1 pathway in lung cancer: i) Bit1 expression is significantly suppressed in various types of NSCLC tissue relative to counterpart normal lung tissue (Fig. 1A and 1B) and ii) an inhibitor of Bit1 function, TLE1, functions as a lung specific oncogene and is overexpressed in human lung tumors (1). While ectopic expression of cytoplasmic localized Bit1 in the NSCLC cell line NCI-H460 induces apoptosis (Fig 1D-F), restoration of mitochondrial localized Bit1 in H460 cells enhances anoikis sensitivity and attenuates anchorage independent growth and resistance to etoposide-induced apoptosis (Fig. 2). Based on the published data and our preliminary results, our objective is to test the hypothesis that malignant NSCLC cells are likely to bypass the Bit1 apoptotic pathway to become anoikis resistant and anchorage-independent, and that activation of the Bit1 pathway may be effective in inducing apoptosis and attenuating the aggressive phenotypes in NSCLC cells. The specific aims are: 1) to examine the regulation and relevance of the Bit1 apoptosis pathway in the survival and apoptotic resistance of NSCLC cells, 2) to test the hypothesis that the Bit1 apoptotic pathway regulates the aggressive phenotypes of NSCLC cells by alteration of mitochondrial Bit1 expression and its impact on anoikis resistance, anchorage- independent growth potential, or chemoresistance of NSCLC cells, and 3) to understand and dissect the apoptotic machinery in NSCLC using Bit1 as a tool. The outcome of this study will delineate the importance of the suppression or blockage of the Bit1 apoptotic pathway in the acquisition of anoikis resistance and anchorage-independence by the NSCLC. We believe that activation of the caspase-independent cell death pathway via the Bit1 apoptotic function will result in a successful eradication of chemoresistance in NSCLC. Thus, Bit-1 may serve as a novel therapeutic target for the treatment of this aggressive cancer. PHS398 (Rev. 5/01) Page Continuation Format Page PUBLIC HEALTH RELEVANCE: A Role of Bit1 in the Apoptosis Resistance, Anoikis Insensitivity, and Chemoresistance in Non-small cell lung cancer (NSCLC) Cells Non-small cell lung cancer (NSCLC) is a highly aggressive disease with poor prognosis and high mortality. The dismal prognosis is in part due to its resistance to conventional chemotherapy and its propensity to disseminate to distant organs. To circumvent the aggressiveness and chemoresistance of NSCLC, it is imperative to identify novel cell death pathway(s) that may enhance the apoptotic sensitivity of NSCLC cells.

描述（由申请人提供）：非小细胞肺癌（NSCLC）是一种高度侵袭性的恶性肿瘤，与转移和化疗反应差有关。非小细胞肺癌细胞表现出对经历凋亡的高抗性，至少部分是由于失能的凋亡机制。特别是，NSCLC细胞中半胱天冬酶依赖性途径的部分缺陷赋予了对DNA损伤剂（如依托泊苷或3-辐射）诱导的细胞凋亡的抗性（9，14）。因此，对抗NSCLC的侵袭性和化疗耐药性的主要治疗途径是通过替代性半胱天冬酶非依赖性细胞死亡途径有效诱导细胞凋亡。本项目的目标是通过获得了解新型非胱天蛋白酶依赖性失巢凋亡效应物Bcl 2-转录抑制剂（Bit 1）在NSCLC细胞凋亡抵抗和恶性转化中的作用所需的信息，解决NSCLC治疗的关键障碍。几项观察结果表明肺癌中Bit 1通路的非功能性：i）与相应的正常肺组织相比，Bit 1表达在各种类型的NSCLC组织中受到显著抑制（图1A和1B）; ii）Bit 1功能抑制剂TLE 1作为肺特异性致癌基因发挥作用，并在人肺肿瘤中过表达（1）。虽然NSCLC细胞系NCI-H460中细胞质定位的Bit 1的异位表达诱导细胞凋亡（图1D-F），但H460细胞中线粒体定位的Bit 1的恢复增强了失巢凋亡敏感性并减弱了锚定非依赖性生长和对依托泊苷诱导的细胞凋亡的抗性（图2）。基于已发表的数据和我们的初步结果，我们的目标是测试的假设，即恶性NSCLC细胞可能绕过Bit 1凋亡途径，成为失巢凋亡抵抗和锚定独立的，Bit 1途径的激活可能是有效的诱导凋亡和减弱NSCLC细胞的侵袭性表型。具体目标是：1）检查Bit 1凋亡途径在NSCLC细胞的存活和凋亡抗性中的调节和相关性，2）检验Bit 1凋亡途径通过改变线粒体Bit 1表达及其对NSCLC细胞的失巢凋亡抗性、锚定非依赖性生长潜力或化学抗性的影响来调节NSCLC细胞的侵袭性表型的假设，3）以Bit 1为工具，了解和剖析NSCLC的凋亡机制。这项研究的结果将描绘的重要性，抑制或阻断的Bit 1凋亡途径的收购失巢凋亡的阻力和锚定非依赖性的NSCLC。我们相信，通过Bit 1凋亡功能激活caspase非依赖性细胞死亡途径将导致成功根除NSCLC的化疗耐药性。因此，Bit-1可以作为治疗这种侵袭性癌症的新的治疗靶点。PHS 398（Rev. 5/01）页 公共卫生关系：Bit 1在非小细胞肺癌（NSCLC）细胞凋亡抵抗、失巢凋亡不敏感性和化疗抗性中的作用非小细胞肺癌（NSCLC）是一种高度侵袭性疾病，预后差，死亡率高。预后不佳的部分原因是它对常规化疗的抵抗力和扩散到远处器官的倾向。为了避免NSCLC的侵袭性和耐药性，必须鉴定可能增强NSCLC细胞凋亡敏感性的新的细胞死亡途径。