肠隐窝异常病灶2,3,5,11,17和18号染色体部分位点的杂合子丢失

Loss of heterozygosity on chromosome loci 2,3,5,11,17,and 18 in aberrant crypt foci of human colon

目的 探讨肠隐窝异常病灶 (ACF)作为结直肠癌最早期癌前形态变化的分子基础。方法 微解剖分离提取 3 4例ACF和 3 5例癌组织的基因组DNA ,全自动DNA测序仪毛细管凝胶电泳检测ACF和癌组织在 2 ,3 ,5 ,11,17和 18号染色体上 9个微卫星位点的杂合子丢失 (LOH)。结果 ACFLOH的发生频率 ( 41 18% )低于癌组织 ( 68 5 7% ) (P <0 0 5 ) ,且两者的LOH发生频率在 18q12、5q12、3p2 1、17q2 1、17q11、11p13和 2p16位点LOH有相似的谱形。在 18q12、5q12、3p2 1、17q2 1和 17q11位点发生频率较高 ,在 11p13和 2p16位点较低。ACF在 18q2 1和 5q2 1位点LOH明显低于癌组织 (P <0 0 5 )。癌组织LOH与肿瘤的部位、大体类型、组织学类型和Dukes分期均无关。LOH呈阳性的ACF ,其同来源的癌组织多见于左半结肠 ,大体以隆起型为主。结论 ( 1)ACF作为结直肠癌黏膜癌前早期的形态改变有其分子遗传学证据 ;( 2 )进一步证实结直肠癌的发生发展是多基因受累。

Objective To study the genetic basis of aberrant crypt foci (ACF), which serve as a very early morphological alteration during the development of carcinogenesis by analyzing the loss of heterozygosity (LOH). Methods DNA from 35 colorectal carcinomas (CRC) and 34 matched ACF were isolated by microdissection. LOH of microsatellite loci at 18q12,18q21,5q12,5q21,3p21,2p16,17q21,17q11 and 11p13 was detected by means of ABI-SEQUENCER and GeneScan software was applied for analysis. Results The rate of LOH in ACF (41.18%) was less than that in carcinoma (68.57%) (P<0.05). The profile of LOH rates at loci 18q12, 5q12, 3p21, 17q21, 17q11, 11p13 and 2p16 in ACF was similar to that in carcinoma. The LOH frequencies on 18q12,18q21,5q12,5q21,and 3p21 were higher than that on 17q11 and 11p13. However the rate at 18q21 and 5q21 in ACF was much lower than that in the carcinoma (P<0.05). The co-existing carcinomas displayed more polypoid growth pattern and located more at the sigmoid colon and rectum. LOH in carcinomas did not correlate with the location, size, type of the carcinoma and Duke′s stage. Conclusions ACF are putative preneoplastic lesions that might represent the earliest morphological lesion with the alteration at molecular genetic level. Our study provides further genetic evidence in the pathogenesis of colorectal carcinomas.