NUCLEOSIDE TRANSPORT INHIBITORS FOR CANCER PREVENTION

用于预防癌症的核苷转运抑制剂

• 批准号: 6878392
• 负责人: John K Buolamwini
• 金额: $ 7.3万
• 依托单位: UNIVERSITY OF TENNESSEE HEALTH SCI CTR
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-22 至 2006-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6878392
• 关键词: antineoplastics; cancer prevention; carcinogenesis; cell line; chemoprevention; combination chemotherapy; cytotoxicity; dehydroepiandrosterone; dipyridamole; drug design /synthesis /production; functional /structural genomics; gene expression; high performance liquid chromatography; messenger RNA; neoplasm /cancer genetics; nucleosides; pharmacokinetics; phorbols; polymerase chain reaction; tamoxifen; transport inhibitor

DESCRIPTION (provided by applicant): Recent studies have shown an overexpression of nucleoside transporters in some human breast, liver, stomach and colorectal cancer tissues, as well as varying profiles of nucleoside transporter subtype gene overexpression among tumors. This might underscore the marked increases in the capacity to take up physiological nucleosides that has been observed as normal cells are transformed into tumor cells. It has also been revealed that nucleoside transporter genes belong to the delayed early proliferative genes class. Taken together, these observations strongly point to a possible role of nucleoside transporters in the carcinogenesis process, at least at the tumor promotion and progression stages. We have recently found that nucleoside transport inhibitors potently antagonize the inhibitory effect of exogenous nucleosides on the antitumor promotion activity of dehydroepiandrosterone (DHEA) against 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced tumor promotion in the JB6 cell carcinogenesis model. This suggests that nucleoside transporters may be involved in the establishment of the tumorigenic phenotype, i.e. promotion of anchorage independent growth characteristics. This is consistent with reports that chemopreventive agents like tamoxifen downregulate nucleoside transporter gene expression. The long-term goal of this research program is to investigate the chemopreventive potential of nucleoside transport inhibitors. The specific aims of this project are: 1) to probe the changes in nucleoside transporter gene expression during JB6 cell tumorigenic transformation, 2) to determine whether nucleoside transport blockers can inhibit carcinogenesis compete against the inhibitory effects of exogenous nucleoside supplies on chemopreventive activity, and 3) to determine structure-activity relationships (SAR) regarding chemoprevention and inhibition of nucleoside transport. The research plan involves experiments to define the role of nucleoside transport inhibition in modulating the effects of chemopreventive agents like DHEA and tamoxifen, in the in vitro JB6 cell carcinogenesis model. Nucleoside transport inhibitors, namely, nitrobenzylthioinosine, dipyridamole and dilazep, as well as novel tetrahydroisoquinolinyl purine riboside inhibitors to be synthesized in the PI's laboratory will be used in these studies. The TPA-induced JB6 P+ cell transformation model using anchorage independent growth as end point, as well as JB6 P+/AP-l-luciferase reporter cell tumor promoter models will be employed for these proof-of-concept in vitro studies. Quantitative analysis of nucleoside transporter gene expression during JB6 tumorigenic transformation will also be carried out by means of real time quantitative RT-PCR. Ancillary studies involving analysis of cellular nucleotide levels by HPLC, and assays of G6PDH activity and its inhibition by DHEA will also be conducted. The mechanistic insights to be gained regarding the carcinogenesis process and its abrogation may lead to the identification of novel molecular targets and agents for cancer prevention.

描述（由申请人提供）： 最近的研究表明，一些人类乳腺癌、肝癌、胃癌和结直肠癌组织中核苷转运蛋白过度表达，并且肿瘤中核苷转运蛋白亚型基因过度表达的情况各不相同。这可能强调了当正常细胞转化为肿瘤细胞时观察到的生理核苷能力的显着增加。还揭示核苷转运蛋白基因属于延迟早期增殖基因类别。综上所述，这些观察结果强烈表明核苷转运蛋白在致癌过程中可能发挥作用，至少在肿瘤促进和进展阶段。我们最近发现，在JB6细胞癌变模型中，核苷转运抑制剂可有效拮抗外源核苷对脱氢表雄酮（DHEA）抗肿瘤促进活性的抑制作用，以对抗12-O-十四烷酰佛波醇-13-乙酸酯（TPA）诱导的肿瘤促进。这表明核苷转运蛋白可能参与致瘤表型的建立，即促进不依赖贴壁的生长特征。这与他莫昔芬等化学预防剂下调核苷转运蛋白基因表达的报道一致。该研究计划的长期目标是研究核苷转运抑制剂的化学预防潜力。该项目的具体目标是：1）探讨JB6细胞致瘤转化过程中核苷转运蛋白基因表达的变化，2）确定核苷转运阻滞剂是否可以与外源核苷供应对化学预防活性的抑制作用竞争抑制致癌作用，以及3）确定化学预防和抑制核苷转运的构效关系（SAR）。该研究计划包括在体外 JB6 细胞癌变模型中进行实验，以确定核苷转运抑制在调节 DHEA 和他莫昔芬等化学预防剂的作用中的作用。这些研究将使用核苷转运抑制剂，即硝基苄基硫代肌苷、双嘧达莫和地拉西普，以及PI实验室合成的新型四氢异喹啉基嘌呤核苷抑制剂。使用贴壁独立生长作为终点的 TPA 诱导的 JB6 P+ 细胞转化模型以及 JB6 P+/AP-1-荧光素酶报告细胞肿瘤启动子模型将用于这些体外概念验证研究。 JB6致瘤转化过程中核苷转运蛋白基因表达的定量分析也将通过实时定量RT-PCR进行。还将进行辅助研究，包括通过 HPLC 分析细胞核苷酸水平，以及 G6PDH 活性及其 DHEA 抑制作用的测定。关于癌发生过程及其消除的机制见解可能会导致识别新的分子靶点和预防癌症的药物。