GENETIC ALTERATIONS AND ALLELIC LOSS IN HUMAN HEPATOCELLULAR CARCINOMA

肝细胞癌是亚洲最常见的癌症之一。 还有非洲。在先前的研究中，中国启东地区的碳氢化合物 常被发现在肿瘤抑制基因p53和 在16号染色体上靠近TAT位点的区域。我们已经将其扩展到 检测60岁以上正常肝组织和肿瘤肝组织的DNA 来自启东和北京的患者。我们利用了微卫星标记 针对16号染色体的长臂(或“Q”)。我们的长期目标 是为了鉴定和鉴定染色体上新的肿瘤抑制基因 16. 14个高度多态的微卫星标记，定位于16q21 和16q24.3，已被用于精细结构分析。 染色体。这些标记的聚合酶链式反应扩增产生两条带 杂合等位基因。如果其中一个显著减少， 肿瘤样本，这表明其中一个等位基因可能缺失。 这种杂合性缺失(LOH)通常是肿瘤的一个指标 缺失区域的抑癌基因。因为肿瘤样本是 通常受到正常组织的污染，定量技术已经 已经开发出来，以允许对 电泳图。这些技术包括分离重叠 由于不完善的聚合酶链式反应而产生的条带卡顿(或阴影) 放大。染色体的破坏被发现是广泛的 沿着16号染色体的映射区域。在63对样本中，只有 11(175)个座位均未检测到显著杂合性缺失。这个 染色体的破坏非常广泛，50%到85%的 在每个基因座上显示可检测到的杂合性缺失的样本。量化 分析表明，染色体上有两到三个“热点” 杂合等位基因的相对条带强度为 与个体的侧翼基因座显著不同。 这可能表明继发性“亚克隆性”杂合性缺失，或者肿瘤组织 是多克隆的。这些结果表明了广泛的染色体破坏。 16号染色体的“Q”臂，所以不太可能有 是一种新的肿瘤抑制基因，定位于TAT位点附近。然而， 通过关注上述热点，我们或许能够本地化 可能含有这种抑癌基因的一个或多个小区域 基因。

Hepatocellular carcinoma (HCC) is one of the most common cancers in Asia and Africa. In a previous study, HCCs from the Qidong region of China were frequently found mutated in the tumor suppressor gene p53 and in a region near TAT locus on chromosome 16. We have extended this by examining DNA from normal and tumor liver tissue obtained from over 60 patients from Qidong and Beijing. We utilized microsatellite markers specific to the long (or "q") arm of chromosome 16. Our long term goal is go identify and characterize new tumor suppressor genes on chromosome 16. Fourteen highly polymorphic microsatellite markers, mapped between 16q21 and 16q24.3, have been used in fine structure analysis of the chromosome. PCR amplification of these markers produces two bands in heterozygous alleles. If one of these is significantly reduced in the tumor sample, it indicates a potential deletion in one of the alleles. Such loss of heterozygosity (LOH) is often an indicator of a tumor suppressor gene in the deleted region. Because the tumor samples are usually contaminated with normal tissue, quantitative techniques have been developed to allow for quantitative analysis of the electrophoretograms. These techniques include separation of overlapping stutter (or shadow) bands that arise because of imperfect PCR amplification. Chromosomal disruption has been found to be extensive along the mapped region of chromosome 16. Out of 63 paired samples, only 11 (175) showed no significant LOH in any of the loci mapped. The disruption of the chromosome was very broad, with from 50 to 85% of the samples displaying detectable LOH at each of the loci. Quantitative analysis indicated two or three "hot spots" along the chromosome where the relative intensities of bands from heterozygous alleles was significantly different from that of flanking loci in an individual. This may indicate secondary "subclonal" LOH, or that the tumor tissue is polyclonal. These results indicate extensive chromosomal disruption of the "q" arm of chromosome 16, and so make it less likely that there is a new tumor suppressor gene localized near the TAT locus. However, by focusing on the above mentioned hot spots, we may be able to localize one or more small regions that might contain such tumor suppressor genes.