Chinnasri Patcharee, Pairojkul Chawalit, Jearanaikoon Patcharee, Sripa Banchob, Bhudhisawasdi Vajarabhongsa, Tantimavanich Srisurang, Limpaiboon Temduang
Department of Clinical Microbiology, Mahidol University, Bangkok, Thailand.
Hum Pathol. 2009 Jun;40(6):817-26. doi: 10.1016/j.humpath.2008.11.002. Epub 2009 Feb 5.
Cholangiocarcinoma in northeast Thailand is associated with liver fluke infection. Mechanisms of inactivation of the p15(INK4b), p16(INK4a), and p14(ARF) have been reported in many human cancers but have not hitherto been studied in liver fluke-related cholangiocarcinoma, particularly genetic and epigenetic effects on protein expression. We investigated loss of heterozygosity and microsatellite instability and performed fine mapping of the chromosomal region 9p21-pter in 94 microdissected cholangiocarcinoma samples using polymerase chain reaction based-microsatellite markers. Methylation and protein expression of p14(ARF), p15(INK4b), and p16(INK4a) was determined using methylation-specific polymerase chain reaction and immunohistochemistry, respectively. Genetic and epigenetic alterations, including loss of protein expression, were correlated with clinicopathological data. Fine mapping at 9p21-pter showed a distinctive region between D9S286 and D9S1752 of common loss. Methylation frequency was 40.2% for p14(ARF), 48.9% for p15(INK4b), and 28.3% for p16(INK4a). Loss of protein expression of p14(ARF), p15(INK4b), and p16(INK4a) was 30.9%, 58%, and 81.5%, respectively. Both p14(ARF) methylation and allelic loss at 9p21 were associated with loss of p14(ARF) expression. Poor prognosis was associated with loss of p16(INK4a) expression. In conclusion, mechanisms of inactivation of p14(ARF), p15(INK4b), and p16(INK4a) in liver fluke-related cholangiocarcinoma are preferentially different, by which epigenetic event being the main mechanism of p14(ARF), whereas p16(INK4a) and p15(INK4b) inactivation occurs through genetic and both genetic and epigenetic events, respectively.
泰国东北部的胆管癌与肝吸虫感染有关。p15(INK4b)、p16(INK4a)和p14(ARF)的失活机制在许多人类癌症中已有报道，但迄今为止尚未在肝吸虫相关的胆管癌中进行研究，尤其是对蛋白质表达的遗传和表观遗传效应。我们研究了94个显微切割的胆管癌样本中9p21 - pter染色体区域的杂合性缺失和微卫星不稳定性，并使用基于聚合酶链反应的微卫星标记进行精细定位。分别使用甲基化特异性聚合酶链反应和免疫组织化学法测定p14(ARF)、p15(INK4b)和p16(INK4a)的甲基化和蛋白质表达。包括蛋白质表达缺失在内的遗传和表观遗传改变与临床病理数据相关。9p21 - pter的精细定位显示在D9S286和D9S1752之间存在一个常见缺失的独特区域。p14(ARF)的甲基化频率为40.2%，p15(INK4b)为48.9%，p16(INK4a)为28.3%。p14(ARF)、p15(INK4b)和p16(INK4a)的蛋白质表达缺失分别为30.9%、58%和81.5%。p14(ARF)甲基化和9p21处的等位基因缺失均与p14(ARF)表达缺失相关。预后不良与p16(INK4a)表达缺失相关。总之,肝吸虫相关胆管癌中p14(ARF)、p15(INK4b)和p16(INK4a)的失活机制存在差异，表观遗传事件是p14(ARF)失活的主要机制，而p16(INK4a)和p15(INK4b)失活分别通过遗传事件以及遗传和表观遗传事件发生。
