Kuroki Tamotsu, Trapasso Francesco, Yendamuri Sai, Matsuyama Ayumi, Alder Hansjuerg, Mori Masaki, Croce Carlo M
Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Cancer Res. 2003 Jul 1;63(13):3724-8.
Promoter hypermethylation is an alternative way to inactivate tumor suppressor genes in cancer. Alterations of chromosome 3p are frequently involved in many types of cancer, including esophageal squamous cell carcinoma. Here, we investigated the methylation status and loss of heterozygosity (LOH) of 3p tumor suppressor genes. We examined the promoter methylation status of von Hippel-Lindau disease (VHL), retinoic acid receptor beta (RAR-beta), RAS association domain family 1A (RASSF1A), and fragile histidine triad (FHIT) genes in 22 esophageal squamous cell carcinoma cell lines and 47 primary tumors and corresponding noncancerous tissues by a methylation-specific PCR. In addition, we analyzed 47 paired samples for LOH at eight loci on chromosome 3p. Hypermethylation in VHL, RAR-beta, RASSF1A, and FHIT was detected in 36, 73, 73, and 50% of tumor cell lines, respectively. In primary tumors, hypermethylation in VHL, RAR-beta, RASSF1A, and FHIT was detected in 13, 55, 51, and 45%, respectively. In corresponding noncancerous tissues, hypermethylation in RAR-beta and FHIT was frequently detected in 38 and 30%, respectively, whereas no VHL hypermethylation and only 4% of RASSF1A hypermethylation were detected. Furthermore, in clinical stages I and II, hypermethylation in RAR-beta (67%) and FHIT (78%) was frequently detected, whereas no VHL hypermethylation and 11% of RASSF1A hypermethylation were detected. On the other hand, the correlation between FHIT hypermethylation and LOH at FHIT region was statistically significant (P = 0.008). Our findings suggest that hypermethylation of the RAR-beta and FHIT may play an important role in the early stage of esophageal squamous cell carcinogenesis. In addition, FHIT may be inactivated in accordance with the two-hit inactivation model, involving deletion of one allele and hypermethylation of the other.
启动子高甲基化是癌症中使肿瘤抑制基因失活的另一种方式。3号染色体短臂的改变频繁见于多种癌症，包括食管鳞状细胞癌。在此，我们研究了3号染色体上肿瘤抑制基因的甲基化状态和杂合性缺失（LOH）情况。我们通过甲基化特异性PCR检测了22个食管鳞状细胞癌细胞系、47例原发性肿瘤及相应癌旁组织中von Hippel-Lindau病（VHL）、视黄酸受体β（RAR-β）、RAS关联结构域家族1A（RASSF1A）和脆性组氨酸三联体（FHIT）基因的启动子甲基化状态。此外，我们分析了47对样本在3号染色体短臂上8个位点的杂合性缺失情况。在肿瘤细胞系中，VHL、RAR-β、RASSF1A和FHIT的高甲基化检出率分别为36%、73%、73%和50%。在原发性肿瘤中，VHL、RAR-β、RASSF1A和FHIT的高甲基化检出率分别为13%、55%、51%和45%。在相应癌旁组织中，RAR-β和FHIT的高甲基化检出率分别为38%和30%，而未检测到VHL高甲基化，RASSF1A高甲基化仅为4%。此外，在临床I期和II期，RAR-β（67%）和FHIT（78%）的高甲基化检出率较高，而未检测到VHL高甲基化，RASSF1A高甲基化仅为11%。另一方面，FHIT高甲基化与FHIT区域杂合性缺失之间的相关性具有统计学意义（P = 0.008）。我们的研究结果表明，RAR-β和FHIT的高甲基化可能在食管鳞状细胞癌发生的早期阶段起重要作用。此外，FHIT可能按照双打击失活模型失活，即一个等位基因缺失，另一个等位基因高甲基化。
