Clinical Significance of Apoptosis in Colon Cancer

描述（由申请人提供）：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，在临床结果中存在相当大的阶段无关的变异性。尽管有辅助治疗，30-40%的III期患者会复发并死于疾病。因此，需要额外的预后标志物来更好地定义从辅助化疗中获益最多的患者亚组。预后和预测性标记物还将使更具选择性、定制和分子靶向的治疗方法成为可能。我们建议研究> 1，000例充分表征的II期和III期结肠癌患者的凋亡调节蛋白，这些患者接受了由北中央癌症治疗组（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。其中一些试验包括未经处理的对照组，使我们能够确定预测效用。细胞凋亡调控的缺陷已被证明有助于肿瘤进展和转移，并且可以赋予对抗癌疗法的抗性。已经定义了两种不同的凋亡信号传导途径，包括膜死亡受体（DR）途径和线粒体途径。线粒体途径的参与导致细胞色素释放，细胞色素释放可以通过抗凋亡Bcl-2和凋亡蛋白抑制剂（IAP）减弱，凋亡蛋白抑制剂结合并抑制半胱天冬酶。DR途径由TNF超家族成员参与，TNF超家族成员作为特异性DR的天然配体。DR通过其胞质死亡结构域介导细胞凋亡。诱饵受体缺乏死亡结构域，但可以竞争配体结合。两种凋亡途径都涉及称为半胱天冬酶的细胞内半胱氨酸蛋白酶的激活，其通过蛋白水解加工被激活并导致凋亡。我们的初步数据表明，凋亡调控蛋白在人类结肠癌中显示肿瘤特异性过表达。此外，我们的数据表明，线粒体途径的负性和正性调节因子分别与较短和较长的患者生存率显著相关。最近的数据还表明，DR 4在结肠癌中过表达，可以提供预后信息，诱骗受体3，Fas信号传导的抑制剂。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块中产生，以使得能够有效地免疫组织化学分析多个凋亡调节蛋白。然后，我们的研究结果将与先前确定的标记物（包括微卫星不稳定性、等位基因丢失和DNA倍性）相关联，并且将产生多变量模型以确定用于并入前瞻性辅助治疗试验的最重要的标记物，所述前瞻性辅助治疗试验涉及3，750例患者将由NCCTG/组间机制进行。

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.