Clinical Significance of Apoptosis in Colon Cancer

描述(申请人提供)：肿瘤分期仍然是人类结直肠癌最重要的预后变量，用于确定是否需要辅助化疗。然而，在临床结果中有相当大的不同阶段的变异性。尽管辅助性治疗，30%-40%的III期患者将复发并死于他们的疾病。因此，需要更多的预后标记物来更好地确定从辅助化疗中获益最多的患者亚群。预后和预测标记物也将使更具选择性、量身定制和分子靶向的治疗方法成为可能。我们建议研究北中癌症治疗小组(NCCTG)和加拿大国家癌症研究所进行的基于5-氟尿嘧啶的辅助治疗试验中接受治疗的患者的&gt；1000例特征良好的II和III期结肠癌患者的凋亡调节蛋白。其中一些试验包括未经处理的对照手臂，使我们能够确定预测效用。细胞凋亡调控的缺陷已被证明与肿瘤的进展和转移有关，并可能导致对抗癌治疗的抵抗。目前已经定义了两条不同的细胞凋亡信号通路，包括膜死亡受体(DR)通路和线粒体通路。线粒体途径的参与导致细胞色素的释放，细胞色素的释放可以被抗凋亡的Bcl-2和与caspase结合并抑制caspase的凋亡蛋白抑制物(LAPS)所减弱。DR通路由肿瘤坏死因子超家族的成员参与，这些超家族充当特定DR的天然配体。DRs通过其胞质死亡结构域介导细胞凋亡。诱骗受体缺乏死亡结构域，但可以竞争配体结合。这两条凋亡途径都涉及到细胞内半胱氨酸蛋白酶的激活，这种半胱氨酸蛋白酶通过蛋白分解过程被激活，并导致细胞凋亡。我们的初步数据表明，凋亡调节蛋白在人类结肠癌中显示出肿瘤特异性的过度表达。此外，我们的数据表明，线粒体途径的负调控和正调控分别与较短和较长的患者存活率显著相关。最近的数据还表明，DR4在结肠癌中过度表达，可以提供预后信息，就像Fas信号的抑制物诱骗受体3一样。我们建议在1,324例结肠癌患者中确定凋亡调节蛋白的预测和预后意义。组织微阵列将从石蜡切片中创建，以实现对多种凋亡调节蛋白的高效免疫组织化学分析。然后，我们的研究结果将与先前确定的标记相关联，包括微卫星不稳定性、等位基因丢失和DNA倍体，并将创建多变量模型，以确定最重要的标记，以纳入由NCCTG/Intergroup机制进行的一项涉及3750名患者的前瞻性辅助治疗试验。

DESCRIPTION (provided by applicant): Tumor stage remains the most important prognostic variable in human colorectal cancers and is used to determine the need for adjuvant chemotherapy. However, there is considerable stage-independent variability in clinical outcome. Despite adjuvant treatment, 30-40% of stage III patients will recur and die of their disease. Accordingly, additional prognostic markers are needed to better define the subset of patients who would benefit most from adjuvant chemotherapy. Prognostic and predictive markers would also enable a more selective, tailored and molecularly- targeted treatment approach. We propose to study apoptotic regulatory proteins in >1,000 well characterized stage II and III colon cancers from patients treated in 5-fluorouracil-based adjuvant therapy trials conducted by the North Central Cancer Treatment Group (NCCTG) and the National Cancer Institute of Canada. Some of these trials include untreated control arms enabling us to determine predictive utility. Defects in the regulation of apoptosis have been shown to contribute to tumor progression and metastasis, and can confer resistance to anti-cancer therapies. Two distinct apoptotic signalling pathways have been defined and include the membrane death receptor (DR) pathway and the mitochondrial pathway. Engagement of the mitochondrial pathway results in cytochrome release which can be attenuated by anti-apoptotic Bcl-2 and by inhibitors of apoptosis proteins (lAPs), which bind to and inhibit caspases. The DR pathway is engaged by members of the TNF superfamily which act as natural ligands for specific DRs. DRs mediate apoptosis through their cytoplasmic death domains. Decoy receptors lack death domains but can compete for ligand binding. Both apoptotic pathways involve activation of intracellular cysteine proteases known as caspases that become activated through proteolytic processing and lead to apoptosis. Our preliminary data indicate that apoptotic regulatory proteins display tumor-specific overexpression in human colon cancers. Moreover, our data suggest that negative and positive regulators of the mitochondrial pathway are significantly associated with shorter and longer patient survival rates, respectively. Recent data also suggest that DR4 is overexpressed in colon cancers and can confer prognostic information, as can decoy receptor 3, an inhibitor of Fas signalling. We propose to determine the predictive and prognostic significance of apoptotic regulatory proteins in 1,324 colon cancer patients. Tissue microarrays will be created from paraffin blocks to enable the efficient immunohistochemical analysis of multiple apoptosis-regulating proteins Our study results will then be correlated with previously determined markers including microsatellite instability, allelic loss, and DNA ploidy and multivariate models will be created to determine the most significant markers for incorporation into a prospective adjuvant therapy trial involving 3,750 patients to be conducted by the NCCTG/Intergroup mechanism.