Lin Ya-Wen, Lee Hsuan-Shu, Chen Chien-Hung, Huang Guan-Tarn, Lee Po-Huang, Sheu Jin-Chuan
Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.
J Gastroenterol Hepatol. 2005 Apr;20(4):536-46. doi: 10.1111/j.1440-1746.2005.03609.x.
Loss of heterozygosity (LOH) on chromosomes 16q and 13q, associated with tumor development, is frequently found in hepatocellular carcinoma (HCC). In light of this, an attempt was made to use the LOH pattern determined by microsatellite markers on 16q and 13q to discriminate clonality.
In an effort to locate the LOH region more precisely and select the appropriate markers, LOH studies on 88 HCC using a panel of 35 microsatellite markers on 16q were carried out. Nine independent regions of frequent LOH were defined. In combination with a previous study of deletion mapping of 13q by the same authors, 12 markers on 16q and 13q were selected and polymerase chain reaction amplification, from microdissection-extracted DNA, was used to allelotype microsatellite polymorphism as an indication of clonality.
Two patterns of LOH were observed. In pattern A, in 8 of 16 (50%) patients, the LOH pattern of the first tumor was preserved in the second sample, with some tumors also showing additional LOH. In these patients, the original and second tumors are presumed to arise from the same original clone with or without progressive accumulation of LOH. In pattern B (8 of 16, 50%), LOH seen in the first tumor was not preserved in the second or recurrent tumors, as evidenced by retention of heterozygosity compared with the first tumor.
The data suggest that the second tumor might have arisen from another independent clone. Moreover, this approach also provides a more sensitive and specific strategy to determine whether multiple or recurrent tumors are derived from the same or a different clone.
16号染色体和13号染色体上杂合性缺失（LOH）与肿瘤发生相关，在肝细胞癌（HCC）中较为常见。鉴于此，人们尝试利用16号染色体和13号染色体上微卫星标记确定的LOH模式来鉴别克隆性。
为更精确地定位LOH区域并选择合适的标记，使用一组位于16号染色体上的35个微卫星标记对88例HCC进行了LOH研究。确定了9个常见LOH的独立区域。结合同一作者先前对13号染色体缺失图谱的研究，选择了16号染色体和13号染色体上的12个标记，并使用聚合酶链反应扩增微切割提取的DNA，以对微卫星多态性进行等位基因分型作为克隆性的指标。
观察到两种LOH模式。在模式A中，16例患者中有8例（50%），第一个肿瘤的LOH模式在第二个样本中得以保留，一些肿瘤还显示出额外的LOH。在这些患者中，原发肿瘤和第二个肿瘤被推测来自同一个原始克隆，可能伴有或不伴有LOH的渐进性积累。在模式B中（16例中的8例，50%），第一个肿瘤中出现的LOH在第二个或复发性肿瘤中未保留，与第一个肿瘤相比杂合性得以保留可证明这一点。
数据表明第二个肿瘤可能来自另一个独立克隆。此外，这种方法还提供了一种更敏感和特异的策略，以确定多个或复发性肿瘤是否源自同一个或不同的克隆。
