MECHANISMS OF LUNG CANCER PREVENTION

肺癌预防机制

• 批准号: 6269724
• 负责人: REUBEN LOTAN
• 金额: $ 10.91万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 1999-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6269724
• 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惨淡的五年 尽管治疗方式有所进步，但存活率是 迫切需要制定新的方法来预防的主要原因 这种可怕的疾病。最近的临床试验表明， 维甲酸作为癌症防治剂。这种潜力正在进一步扩大 在这个以肺癌为重点的计划项目中进行了探索。的目标是 该项目旨在提供对维甲酸作用机制的深入了解。 正常、癌前和恶性的支气管和肺组织和细胞 以补充临床研究。据认为，维甲酸对 它们通过改变影响细胞的基因的表达来发挥作用 生长和分化。维甲酸激活两种类型的核 视黄醇受体(RARs和RXRs)，存在于三个亚型(α， β和伽马)各自作为转录因子。初步数据 显示在发育不良和恶性肺组织中RARbeta水平降低 在活体内。这些和其他发现提出了RARbeta发挥作用的假设 在抑制癌症发生中的作用，即下调 RARbeta通过以下方式使癌前细胞逃脱监视 维甲酸的生理水平，一些维甲酸可以 药理剂量可克服某些癌前病变的耐药性 细胞，可能是通过增加RARbeta的表达。这个项目是专门设计的 为了了解视黄醇受体，特别是RARbeta的参与， 在肺癌发生中的作用。首先，它们的表达式将在 肺癌的手术标本，支气管组织的活检 L计划对13-顺式维甲酸和α-维甲酸治疗前后的患者进行比较 生育酚，以及正常支气管单层和器官培养 上皮细胞、癌前细胞和肺癌细胞。这个 受体的mRNAs将通过原位杂交和Northern分析 吸墨水。为了研究维甲酸对肺细胞的调节作用， 天然和合成维甲酸对不同类型的 受体类型对维甲酸受体表达的影响 正常支气管的增殖、凋亡和分化 上皮细胞、永生化的支气管细胞和恶性肺细胞 在单层培养、器官型培养和半固体培养中 将会被确定。增殖将通过细胞计数和 BrdU掺入、DNA梯状结构诱导的细胞凋亡、DNA末端标记 TERMINI、流式细胞术和免疫组织化学鉴定 和细胞角蛋白7和13的Western blotting分析。 RARbeta表达或阻断是否改变癌前病变的反应 维甲酸对细胞生长和肺癌细胞生长的影响 区分，正义和反义RARbeta都将被介绍 通过逆转录病毒载体瞬时或稳定地进入细胞 表达或不表达该受体，并且 将检查细胞对维甲酸的反应。最后，确定 RARbeta是否在肺癌细胞的致瘤性中起作用 外源RARbeta的表达和表达RARbeta的细胞 被反义RARbeta阻断后将被注射到皮下 免疫受损的小鼠和它们的致瘤性将被确定。这些 预计研究将增加对参与的了解 RARbeta在细胞对不同维甲酸类化合物反应中的作用 肺癌细胞的致瘤性。此外，新的维甲酸具有 在化学预防试验中的潜在应用可能被确定。