A novel mouse colon cancer model and chemoprevention

纺锤体检查点延迟了从中期到后期的进程，直到所有浓缩的染色体 正确地附着在有丝分裂的纺锤体上检查点功能受损通常会导致基因组 不稳定性，使细胞易于发生恶性转化。为了理解 在人类癌症发展中，这种监视机制的功能失活，Pi的实验室已经 专注于BubRl（一种关键的纺锤体检查点激酶）在维持基因组稳定性中的作用， 抑制肿瘤发生。Pi组产生了BubRl+/-小鼠以及BubRl+/-ApcMin/+小鼠。 复合突变小鼠BubRl+/-小鼠在施用后以加速的速率发展肠腺癌。 氧化偶氮甲烷处理。而ApcMin/+小鼠通常在肿瘤内形成许多腺瘤性息肉。 小肠，BubRl+/-ApcMin/+复合突变小鼠发展出显著更自发的结肠炎， 肿瘤比ApcMin/+小鼠。BubRl+/-ApcMin/+小鼠中的结肠肿瘤在临床上更晚期 比在ApcMin/+小鼠中观察到的要多。此外，化学预防化合物如舒林酸硫化物和 S-烯丙基巯基半胱氨酸能够在HT-29和SW-480结肠肿瘤细胞中诱导凋亡; BubRl - 缺陷细胞对这些化合物诱导的细胞凋亡更有抗性。考虑到BubRl和Ape 参与正常细胞中基因组稳定性的调节，我们假设BubRl+/-ApcMin+/- 小鼠将是用于评价各种化合物的抗肿瘤活性的功效的优良啮齿动物模型。 靶向结肠的化学预防化合物和了解纺锤体检查点的体内作用 维持基因组稳定性的成分。为了验证这一假设，Pi的实验室将（i）验证和 测试舒林酸和S-烯丙基巯基半胱氨酸的化学预防作用，S-烯丙基巯基半胱氨酸（或其衍生物） 直接靶向微管或有丝分裂纺锤体，抑制自发性肠肿瘤发生， BubRl+/- ApcMin/+复合突变小鼠，和（ii）研究肠上皮细胞凋亡的分子基础。 通过研究这些突变小鼠的基因组不稳定性和自发癌变率， （B）BubRl和/或Ape缺陷的细胞的转化， 舒林酸和S-烯丙基巯基半胱氨酸对纺锤体检查点完整性的影响，以及（c） 其中ApcMin/+小鼠在BubRl缺陷型基因中肿瘤负荷从小肠转移到结肠， 背景这个项目的长期目标是阐明细胞周期检查点的机制， Wnt信号通路调节细胞增殖和分化以及基因组稳定性。

The spindle checkpoint delays the progression from metaphase to anaphase until all condensed chromosomes are properly attached to mitotic spindles. An impaired checkpoint function often results in genomic instability, which predisposes cells to malignant transformation. To understand the molecular basis of functional inactivation of this surveillance mechanism in human cancer development, the Pi's laboratory has focused on the role of BubRl, a key spindle checkpoint kinase, in the maintenance of genomic stability and suppression of tumorigenesis. The Pi'sgroup has generated BubRl+/- mice as well as BubRl+/-ApcMin/+ compound mutant mice. BubRl+/- mice develop intestinal adenocarcinomas at an accelerated rate after azoxymethane treatment. Whereas ApcMin/+ mice develop many adenomatous polyps generally within the small intestine, BubRl+/-ApcMin/+ compound mutant mice develop significantly more spontaneous colonic tumors than ApcMin/+ mice. The colon tumors in BubRl+/-ApcMin/+ mice are clinically more advanced than those observed in ApcMin/+ mice. Moreover, chemopreventive compounds such as sulindac sulfide and S-allylmercaptocysteine are capable of inducing apoptosis in HT-29 and SW-480 colon tumor cells; BubRl - deficient cells are more resistant to apoptosis induced by these compounds. Given that both BubRl and Ape are involved in the regulation of genomic stability in normal cells, we hypothesize that BubRl+/-ApcMin+/- mice would be an excellent rodent model for evaluating the efficacy of anti-tumor activities of various chemopreventive compounds that target colon and understanding the in vivo role of spindle checkpoint components in the maintenance of genomic stability. To test this hypothesis, the Pi's lab will (i) validate and test the chemopreventive effect of sulindac and S-allylmercaptocysteine, which (or the derivative of which) directly target microtubules or mitotic spindles, on suppression of spontaneous intestinal tumorigenesis in BubRl+/- ApcMin/+ compound mutant mice, and (ii) investigate the molecular basis of intestinal carcinogenesis in these mutant mice by studying (a) the genomic instability and the rate of spontaneous transformation of cells deficient in BubRl and/or Ape, (b) the dependence of anti-proliferative effect of sulindac and S-allylmercaptocysteine on the integrity of the spindle checkpoint, and (c) the mechanism by which ApcMin/+ mice shift in tumor burden from the small intestine to colon in the BubRl-deficient genetic background. The long-term goal of this project is to elucidate the mechanism by which cell cycle checkpoints and the Wnt signaling pathway regulate cell proliferation and differentiation as well as genomic stability.