Branham M T, Pellicer M, Campoy E, Palma M, Correa A, Roqué M
Institute of Histology and Embryology (IHEM-CCT-CONICET) and School of Medical Sciences, National University of Cuyo, M5502JMA Mendoza, Argentina.
Pathology Laboratory, J5402EQC San Juan, Argentina.
Case Rep Gastrointest Med. 2014;2014:371638. doi: 10.1155/2014/371638. Epub 2014 Dec 4.
Leiomyomas constitute 2.5% of all resected neoplasms of the stomach. They are usually asymptomatic, but may present mucosal ulceration. Aberrant DNA methylation is a well-defined epigenetic change in human neoplasms; however, gene-acquired methylation may not necessarily be related with a malignant phenotype. In this report we analyzed in a gastric leiomyoma, the methylation status of 84 CpGI in tumor suppressor and DNA repair genes. We analyzed the tumor center (TC) and tumor periphery (TP) separately. We found aberrant methylation in 2/84 CpGI in the TC portion, that is, MLH1 and MSH3, and 5/84 CpGI in the TP, that is, MLH1, MSH3, APC, MSH6, and MGMT. The gene with the highest methylation percentage in the TC and TP was MLH1. Given that MLH1 methylation has been associated with microsatellite instability, we analyzed the status of the microsatellite Bat-26. We found that neither the TC nor the TP presented instability. The methylation of MLH1, MGMT, and APC has been described in GISTs, but to the best of our knowledge this is the first time that the methylation of these genes has been associated with gastric leiomyoma. Further research should be conducted to identify reliable molecular markers that could differentiate between GISTs and gastric leiomyomas.
平滑肌瘤占所有胃切除肿瘤的2.5%。它们通常无症状，但可能出现黏膜溃疡。异常DNA甲基化是人类肿瘤中一种明确的表观遗传变化；然而，基因获得性甲基化不一定与恶性表型相关。在本报告中，我们分析了胃平滑肌瘤中84个CpGI在肿瘤抑制基因和DNA修复基因中的甲基化状态。我们分别分析了肿瘤中心（TC）和肿瘤周边（TP）。我们在TC部分的84个CpGI中发现2个异常甲基化，即MLH1和MSH3，在TP中发现5个异常甲基化，即MLH1、MSH3、APC、MSH6和MGMT。在TC和TP中甲基化百分比最高的基因是MLH1。鉴于MLH1甲基化与微卫星不稳定性相关，我们分析了微卫星Bat-26的状态。我们发现TC和TP均未出现不稳定性。MLH1、MGMT和APC的甲基化在胃肠道间质瘤（GIST）中已有报道，但据我们所知，这是首次将这些基因的甲基化与胃平滑肌瘤相关联。应进一步开展研究以确定能够区分GIST和胃平滑肌瘤的可靠分子标志物。
