Clonality Assessment and Clonal Ordering of Individual Neoplastic Crypts Shows Polyclonality of Colorectal Adenomas
Clonality Assessment and Clonal Ordering of Individual Neoplastic Crypts Shows Polyclonality of Colorectal Adenomas
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DOI：
10.1053/j.gastro.2010.01.033
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发表时间：
2010-04-01
期刊：
影响因子：
29.4
通讯作者：
Leedham, Simon J.
中科院分区：
文献类型：
--
作者：
Thirlwell, Christina;Will, Olivia C. C.;Leedham, Simon J.
背景与目的：根据体细胞突变理论，单克隆结直肠病变是由单个干细胞后代的连续突变引起的。然而，对性染色体混合倍体镶嵌（XO/XY）患者的研究表明，结直肠腺瘤是多克隆的。我们评估了单个隐窝的腺瘤克隆性，并完成了腺瘤癌的遗传依赖性分析，以评估突变顺序和时间。方法：对 XO/XY 个体、家族性腺瘤性息肉病和减毒型家族性腺瘤性息肉病患者、小散发性腺瘤患者和散发性腺瘤内癌患者的息肉样本进行分析。使用X/Y染色体荧光原位杂交、XO/XY组织中5q杂合性丢失分析以及腺瘤性息肉病大肠杆菌测序来分析克隆性。对单个隐窝和腺瘤内癌病变的不同表型区域进行了腺瘤性息肉病大肠杆菌、p53 和 K-RAS 突变的分析； 5q、17p 和 18q 杂合性丢失；和非整倍体。构建了系统发育树。结果：所有家族性腺瘤性息肉病相关腺瘤和一些散发性病变均具有多克隆遗传缺陷。一些独立的克隆似乎保留在晚期腺瘤中。遗传事件的明确必然顺序尚未建立。发育不良组织自上而下生长到邻近的隐窝中是克隆竞争的一种可能机制。结论：人类结直肠微腺瘤是多克隆的，可能是由宿主遗传特征、粘膜暴露和活跃的隐窝相互作用共同引起的。肿瘤系统发育分析表明，大多数病变经历间歇性遗传同质化，但异型突变模式表明，在整个腺瘤发展过程中可以发生独立的克隆进化。根据对克隆排序的观察，肿瘤进展过程中遗传事件的要求和时间可能比之前想象的更加多变。
BACKGROUND & AIMS: According to the somatic mutation theory, monoclonal colorectal lesions arise from sequential mutations in the progeny of a single stem cell. However, studies in a sex chromosome mixoploid mosaic (XO/XY) patient indicated that colorectal adenomas were polyclonal. We assessed adenoma clonality on an individual crypt basis and completed a genetic dependency analysis in carcinomas-in-adenomas to assess mutation order and timing. METHODS: Polyp samples were analyzed from the XO/XY individual, patients with familial adenomatous polyposis and attenuated familial adenomatous polyposis, patients with small sporadic adenomas, and patients with sporadic carcinoma-in-adenomas. Clonality was analyzed using X/Y chromosome fluorescence in situ hybridization, analysis of 5q loss of heterozygosity in XO/XY tissue, and sequencing of adenomatous polyposis coli. Individual crypts and different phenotypic areas of carcinoma-in-adenoma lesions were analyzed for mutations in adenomatous polyposis coli, p53, and K-RAS; loss of heterozygosity at 5q, 17p, and 18q; and aneuploidy. Phylogenetic trees were constructed. RESULTS: All familial adenomatous polyposis-associated adenomas and some sporadic lesions had polyclonal genetic defects. Some independent clones appeared to be maintained in advanced adenomas. No clear obligate order of genetic events was established. Top-down growth of dysplastic tissue into neighboring crypts was a possible mechanism of clonal competition. CONCLUSIONS: Human colorectal microadenomas are polyclonal and may arise from a combination of host genetic features, mucosal exposures, and active crypt interactions. Analyses of tumor phylogenies show that most lesions undergo intermittent genetic homogenization, but heterotypic mutation patterns indicate that independent clonal evolution can occur throughout adenoma development. Based on observations of clonal ordering the requirement and timing of genetic events during neoplastic progression may be more variable than previously thought.