MECHANISMS OF LUNG CANCER PREVENTION

肺癌预防机制

• 批准号: 6218884
• 负责人: REUBEN LOTAN
• 金额: $ 6.93万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-07 至 2001-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6218884
• 关键词: DNA; apoptosis; biopsy; cancer prevention; carcinogenesis inhibitor; cell cycle; cell differentiation; cell line; cell sorting; chemoprevention; cooperative study; human genetic material tag; human tissue; immunocytochemistry; in situ hybridization; keratin; lung neoplasms; molecular oncology; preneoplastic state; receptor expression; respiratory epithelium; retinoid binding proteins; tissue /cell culture; tocopherols; transfection; vitamin receptor

The high mortality rate of lung cancer patients and the dismal 5-year survival rate despite the advancement in treatment modalities are the major reasons for the urgent need to devise novel approaches to prevent this dreadful disease. Recent clinical trials revealed the potential of retinoids as cancer preventive agents. This potential is being further explored in this program project focusing on lung cancer. The objective of this project is to provide insights into mechanisms of retinoid actions on normal, premalignant, and malignant bronchial and lung tissues and cells to complement the clinical studies. It is thought that retinoids exert their actions by changing the expression of genes that influence cell growth and differentiation. Retinoids activate two types of nuclear retinoid receptors (RARs and RXRs), which exist in three subtypes (alpha, beta, and gamma) each and act as transcription factors. Preliminary data show that RARbeta level decreases in dysplastic and malignant lung tissue in vivo. These and other findings raised the hypotheses that RARbeta plays a role in suppression of carcinogenesis, that the down regulation of RARbeta enables premalignant cells to escape the surveillance by physiological levels of retinoids, and that some retinoids can at pharmacological doses overcome the resistance of certain premalignant cells, perhaps by increasing RARbeta expression. This project is designed to understand the involvement of retinoid receptors in particular RARbeta, in lung carcinogenesis. First, their expression will be determined in surgical samples of lung carcinomas, biopsies of bronchial tissue from Project l patients before and after treatment with 13-cis-RA and alpha- tocopherol, and in monolayer and organotypic cultures of normal bronchial epithelial cells, premalignant cells, and lung carcinoma cells. The receptors' mRNAs will be analyzed by in situ hybridization and Northern blotting. To examine the modulation of lung cells by retinoids, the effects of natural and synthetic retinoids with preferences for distinct receptor types on the expression of retinoid receptors, and on proliferation, apoptosis, and differentiation of normal bronchial epithelial cells, immortalized bronchial cells, and malignant lung cells in monolayer cultures, in organotypic cultures, and in semisolid medium will be determined. Proliferation will be determined by cell counting and BrdU incorporation, apoptosis by DNA ladder formation, end labeling of DNA termini, and flow cytometry, and differentiation by immunohistochemical and Western blotting analyses of cytokeratins 7 and 13. To determine whether RARbeta expression or blockade alter the response of premalignant cells and lung carcinoma cell to effects of retinoids on cell growth and differentiation, both the sense and antisense RARbeta will be introduce transiently or in a stable fashion by retroviral vectors into cells that either express or do not express this receptor constitutively and the responses of the cells to retinoids will be examined. Lastly, to determine whether RARbeta plays a role in tumorigenicity, lung carcinoma cells expressing exogenous RARbeta and cells in which RARbeta expression was blocked by antisense RARbeta will be injected subcutaneously into immunocompromised mice and their tumorigenicity will be determined. These studies are expected to increase the understanding of the involvement of RARbeta in the cellular responses to different retinoids and its role in the tumorigenicity of lung carcinoma cells. In addition new retinoids with potential application in chemoprevention trials may be identified.

肺癌患者的高死亡率和5年惨淡的死亡率 尽管治疗方式进步，但生存率是 迫切需要设计新方法以防止的主要原因 这种可怕的疾病。最近的临床试验揭示了 视网膜类似作为癌症预防剂。这种潜力正在进一步 在该计划项目中探索了针对肺癌的项目。目的 该项目旨在洞悉类视黄素动作机制 正常，预调子和恶性支气管和肺组织以及细胞 补充临床研究。据认为类维生素类动物施加 他们的作用通过改变影响细胞的基因的表达 生长与分化。视网膜类似于两种类型的核 类视视感受体（RARS和RXR）存在于三个亚型（alpha， beta和伽玛）每个都充当转录因子。初步数据 证明rarbeta水平降低了发育不良和恶性肺组织 体内。这些发现和其他发现提出了Rarbeta扮演的假设 在抑制癌变中的作用 rarbeta使预示威细胞能够通过 类维生素类似的生理水平，某些类视网膜类似可以 药理学剂量克服了某些预抗药性的抗药性 细胞，也许是通过增加rarbeta表达。这个项目是设计的 要了解类视黄素受体特别是rarbeta的参与， 在肺癌发生中。首先，他们的表达将在 肺癌的手术样本，来自支气管组织的活检 用13-CIS-RA和α-治疗前后的L项目患者 生育酚，以及正常支气管的单层和器官型培养物 上皮细胞，预调子细胞和肺癌细胞。这 将通过原位杂交和北部分析受体的mRNA 吸毒。为了检查性类维生素的调节肺细胞， 天然和合成类维生素的影响，偏爱明显 受体类型的类视黄素受体的表达，以及 正常支气管的增殖，凋亡和分化 上皮细胞，永生的支气管细胞和恶性肺细胞 在单层文化中 将确定。增殖将由细胞计数确定，并且 BRDU掺入，DNA梯子形成的凋亡，DNA的终端标记 末端和流式细胞仪以及免疫组织化学的分化 以及细胞角蛋白7和13的蛋白质印迹分析。 rarbeta表达式还是封锁改变了预抗响应的响应 细胞和肺癌细胞对类维生素类似对细胞生长的影响和 差异化，感官和反义rarbeta都将被介绍 通过逆转录病毒向量瞬时或以稳定的方式进入细胞 要么表达或不构成表达该受体， 将检查细胞对视视视网想的反应。最后，确定 Rarbeta是否在肿瘤性，肺癌细胞中起作用 表达rarbeta表达的外源性rarbeta和细胞 被反义的rarbeta阻塞将被皮下注入 将确定免疫受损小鼠及其肿瘤性。这些 期望研究会增加对参与的理解 rarbeta在细胞对不同类动物的反应中及其在 肺癌细胞的致瘤性。此外，新的类线虫与 可以确定在化学预防试验中的潜在应用。