HUMAN MUTATOR GENES AND THERAPEUTIC EFFICACY IN COLORECTAL CANCER

遗传性非息肉病性结直肠癌(HNPCC)占结直肠癌的6%-10%，主要与人类错配修复(MMR)基因hMSH2和hMLH1的胚系改变有关。另外三个MMR基因[hMSH3、hMSH6和hPMS2]在体外显示了MMR功能，但在HNPCC中很少改变。除HNPCC外，平均有10%-20%的所有类型的散发性肿瘤表现出微卫星不稳定(MCI)，这是人类MMR缺陷的特征。人类的MMR基因与从细菌到人类的高度保守的MMR蛋白家族有关。我们已经开发了国际公认的导致肿瘤发生的MMR途径的程序(S)。此外，我们还发现了一种由MMR基因用来指导修复和/或凋亡的新的信号机制。我们建议：1.)确定已知的MMR基因(Hmsh2、Hmsh3、MSH6、hMLH1和hPMS2)中哪些基因发生了改变，然后进行外显子直接测序、组织荧光原位杂交(FISH)和开发其他新的突变检测方案；确定与非整倍体途径肿瘤相比，MSI肿瘤中哪一种MMR途径基因组合发生了改变：a.)P53、K-ras、TGFRII、IGF-RII、Bax、Tcf-4、β-catinin和染色体18q LOH的序列；以及b)APC、FHIT、P53、p21、Bcl2、PLA2g2s的IHC序列；检测顺铂、MNNG、CPT-11、5-氟尿嘧啶和电离辐射对基因定义的MMR缺陷细胞的细胞影响，以作为治疗效果的预测指标；以及确定与MMR信号转导下游效应器相关的功能后果/过程，从而在体外和体内导致DNA修复和/或凋亡。这些研究是直截了当的，应该提供一个关于人类MMR基因功能变化的数据库，并为MMR途径肿瘤的诊断和治疗效果奠定坚实的基础。

Hereditary Non-Polyposis Colorectal (HNPCC) accounts for 6-10% of colorectal cancers and is primarily associated with germline alterations in the human mismatch repair (MMR) genes hMSH2 and hMLH1. Three other MMR genes [hMSH3, hMSH6 and hPMS2] have demonstrated MMR functions in vitro but are rarely altered in HNPCC. In addition to HNPCC, an average of 10-20% of sporadic tumors of all types manifest microsatellite instability (MCI) that is a hallmark of a human MMR defect. The human MMR genes are related to highly conserved families of MMR proteins identified from bacteria to man. We have developed the internationally recognized procedure(s) for the MMR-pathway leading to tumorigenesis. Moreover, we have discovered a novel signaling mechanism used by the MMR genes to direct repair and/or apoptosis. We propose to: 1.) determine which of the known MMR genes (Hmsh2, Hmsh3, MSH6, hMLH1 and hPMS2) are altered analysis, followed by direct exon sequencing, tissue Fluorescent in situ hybridization (FISH) and the development of other novel mutational detection schemes; II.) determine which of a combination of MMR-pathway genes are altered in MSI tumors in comparison to Aneuploid-Pathway tumors by: a.) sequence for p53, K-ras, TGFRII, IGF-RII, BAX, Tcf-4, beta-catinin, and chromosome 18q LOH; and b) IHC for APC, FHIT, p53, p21, Bcl2, PLA2g2s; III.) det4ermine the cellular consequences of exposures to cisplatinum, MNNG, CPT-11, 5-Fluorouracil and ionization radiation on genetically defined MMR defective cell, to be used as a predictor of therapeutic efficacy; and IV.) determine the functional consequences/processes associated with MMR signaling to downstream effectors leading to DNA repair and/or apoptosis in vitro and in vivo. These studies are straight-forward and should provide a database on the functional alterations of the human MMR genes if colorectal tumors as well as a firm foundation for diagnostic and therapeutic efficacy of MMR-Pathway tumors.