Elucidation of the genesis mechanism of early lesions of colon cancer-Toward the elucidation of early lesions of de novo colorectal ceancer in humans

ACF- d (I)属于典型ACF的发育不良病变。ACF-D（II）由与正常隐窝相同或小于正常隐窝的隐窝组成，可检测到黏蛋白丢失，高度发育不良病变，传统染色方法难以检测，但可通过鉴别染色方法检测（Ochiai et al., Cancer Lett, 220:67- 74,2005）。通过啮齿动物结肠癌模型，我建议明确ACF-D（II）的发生机制，研究ACF-D（II）是否可能是新生结直肠癌的早期病变，并阐明其特征。下面以偶氮甲烷致大鼠结肠病变为例进行分析。ACF-D发生机制的基因特异性分析（II）免疫组织化学分析。在5例黏液蛋白缺失的ACF-D（II）中，结肠黏液的主要成分Muc2蛋白缺失，而胃黏液的主要成分Muc5AC蛋白未见异位表达。在ACF-D（II）中，通过Muc2启动子激活Muc2基因表达的Cdx2蛋白的表达与正常隐窝和ACF-D(I)中的表达几乎相同。Runx3是TGF-β超家族的靶点，是一种推定的肿瘤抑制基因。5种ACF-D(I)中未检测到Runx3蛋白的缺失，但4种ACF-D（II）中均检测到Runx3蛋白的缺失。这表明Runx3蛋白的丢失经常发生在ACF-D（II）中，而不是ACF-D(I)中。进一步验证Runx3蛋白的丢失是否在ACF-D（II）中具有特异性2。使用array-CGHIn对三种结肠癌细胞ACF-D（II）的发生机制进行基因组综合分析，未检测到拷贝数畸变（CNA）与复数探针的连续丢失。因此，估计在结肠癌前病变ACF-D（II）中可能检测不到CNA。

ACF-D(I) is a dysplastic lesion which belongs to classical ACF. ACF-D(II) is composed of crypts the as same as or smaller than normal crypts, detected mucin loss, high grade dysplastic lesions, and is hard to detect by classical staining methods but can be detected by a differential staining method (Ochiai et al., Cancer Lett, 220:67-74, 2005). Using a colon cancer model in rodents, I propose that the genesis mechanism of ACF-D(II) be made clear, and study whether ACF-D(II) may be an early lesion of de novo colorectal cancer and the character of that be elucidated. This was analyzed in the points below using colonic lesions of rats induced by azoxymethane.1. Gene-specific analysis of the genesis mechanism of ACF-D(II) using immunohistochemical analysis.In all five ACF-D(II) with mucin loss, Muc2 protein, which is major component of mucus in colon, was lost but dystopic expression of Muc5AC protein, which is a major component of mucus in the stomach, was not detected. In ACF-D(II), the expression of Cdx2 protein, which activated gene expression of Muc2 through Muc2 promoter, was almost the same as those in normal crypts and ACF-D(I).Runx3 is the target of the TGF-β superfamily and a putative tumor suppressor gene. Loss of Runx3 protein was not detected in five ACF-D(I), but detected in all four ACF-D(II). It was suggested that loss of Runx3 protein frequently occurred in ACF-D(II) but not ACF-D(I). Furthermore, it will be verified whether loss of Runx3 protein is specific in ACF-D(II) or not.2. Comprehensive analysis in genome of the genesis mechanism of ACF-D(II) using array-CGHIn three colon cancers, copy number aberration (CNA) with continuous loss of plural probes was not detected. So it was estimated that CNA may not be detected in ACF-D(II), pre-cancerous lesions in colon.