MEVALONATE DYSREGULATION--POTENTIAL THERAPY COLON CANCER

甲羟戊酸失调——结肠癌的潜在治疗方法

• 批准号: 2098408
• 负责人: SELWYN A BROITMAN
• 金额: $ 19.37万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-07-01 至 1998-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2098408
• 关键词: HMG coA reductases; adenoma; athymic mouse; carcinoma; cell growth regulation; cholesterol; colon neoplasms; genetic regulation; genetic transcription; guanine nucleotide binding protein; human tissue; immunocytochemistry; isoprenoid; lipid biosynthesis; liver neoplasms; low density lipoprotein; metastasis; mevalonate; neoplasm /cancer chemotherapy; neoplastic growth; northern blottings; oxidoreductase inhibitor; polymerase chain reaction; receptor; tissue /cell culture

Certain colon tumor hepatic metastases exhibit a deficiency of LDL receptors (LDL-R); additionally, colon tumor cell lines, unlike normal fibroblasts or hepatocytes, are unable to reverse a mevinolin imposed inhibition of HMGCoA reductase (HMGCoA-R) in the presence of LDL. Receptor deficiency could lead to, or result from, an enhanced activity of HMGCoA- R, the key enzyme regulating synthesis of mevalonate and its derivatives. Due to the central role mevalonate metabolism plays in mammalian cells, higher endogenous concentrations of the constituents of this pathway could affect the degree to which the ras protein is incorporated into the plasma membrane, potentially permitting a higher degree of ras activity in such colonic tumors. Thus an enhancement of ras activation is potentially a selective force in the development of colon cancers that may lead to a deficiency in LDL-R expression, or an uncoupling of this pathway to cellular growth needs. The magnitude of the dysregulation of the reductase and its potential effect on the expression of the product of the ras oncogene will be determined to examine the etiologic importance of these changes in the development of certain colon cancers. The response of the cells to either mevinolin inhibition of Reductase, or growth in the presence of exogenous sterols as LDL, will be assessed in vitro and in vivo in regard to: 1) HMGCoA-R activity, and 2)transcription of the LDL-R and HMGCoA-R genes. The role of mevinolin treatment in anchorage independent growth in vitro in relation to the ras protein's: 1)isoprenylation 2) membrane association and 3) activity, will be evaluated. The ability of mevinolin treatment to affect the expression of the ras protein in vivo will be determined using tumors implanted into the hepatic site of nude mice. Intrasplenic inoculations of the tumors will be accomplished as an assessment of the impact of mevinolin treatment (ras isoprenylation) upon the metastatic propensity of the tumors in vivo. The impact of exogenously supplied human LDL upon mevinolins action will be determined. The significance of dysregulations of this pathway which can lead to or be caused by LDL-R deficiency or loss will be evaluated in human colonic tissues ranging from adenomas to carcinoma in situ and hepatic metastases by IgGC-7 staining for LDL-R, northern blot for both LDL-R and HMGCoA-R gene expression, and concurrent analysis of the membrane expression and transformed character of cellular ras genes by FITC and PCR techniques. An understanding of the control of the mevalonate pathway in colon tumors may provide a cohesive theory incorporating the proliferative response in normal and transformed colonic mucosal cells in relation to loss of LDL-R function, subsequent dysregulation of the mevalonate/cholesterol biosynthetic pathway, farnesylation of the ras protein, and the oncogenic process.

某些结肠肿瘤肝转移表现出LDL缺乏 受体（LDL-R）;此外，结肠肿瘤细胞系，与正常 成纤维细胞或肝细胞，不能逆转mevinolin强加的 在LDL存在下抑制HMGCoA还原酶（HMGCoA-R）。受体 缺乏可能导致或导致HMGCoA- R是调节甲羟戊酸及其衍生物合成的关键酶。 由于甲羟戊酸代谢在哺乳动物细胞中起着重要作用， 该途径的成分的较高内源性浓度可 影响ras蛋白掺入血浆的程度 膜，潜在地允许更高程度的ras活性， 结肠肿瘤 因此，ras激活的增强可能是一个潜在的机制。 结肠癌发展中的选择性力量，可能导致 LDL-R表达缺陷，或该途径与 细胞生长的需要。还原酶的失调程度 及其对ras产物表达的潜在影响 癌基因将被确定，以检查这些病因的重要性， 某些结肠癌的发展变化。的响应 细胞的mevinolin抑制还原酶，或生长在 将在体外和体内评估外源性固醇（如LDL）的存在。 体内：1）HMGCoA-R活性，和2）LDL-R的转录 和HMGCoA-R基因。美维诺林治疗在支抗中的作用 与ras蛋白相关的体外独立生长： 1)异戊二烯化2）膜缔合和3）活性，将被 评估。mevinolin处理影响表达的能力， 体内的ras蛋白将使用移植到 裸鼠肝脏部位。肿瘤的脾内接种将是 作为对mevinolin治疗（RAS）影响的评估完成 异戊二烯化）对体内肿瘤转移倾向的影响。的 外源性提供人LDL对mevinolin作用的影响将 测定这一途径失调的重要性， 导致或由LDL-R缺乏或损失引起的，将在 从腺瘤到原位癌的人类结肠组织， 通过IgGC-7染色检测LDL-R，北方印迹检测两者 LDL-R和HMGCoA-R基因表达，同时分析 细胞ras基因的膜表达和转化特性 FITC和PCR技术。对甲羟戊酸控制的认识 在结肠肿瘤中的通路可能提供了一个结合了 正常和转化结肠粘膜细胞的增殖反应， 与LDL-R功能丧失、随后的 甲羟戊酸/胆固醇生物合成途径，ras的法尼基化 蛋白质和致癌过程。