肝癌胰岛素样生长因子-Ⅱ表观遗传改变与其基因转录、表达的相关性分析

Correlation between epigenetic alterations in the insulin growth factor-Ⅱ gene and hepatocellular carcinoma

目的分析胰岛素样生长因子（IGF）-Ⅱ表观遗传改变与基因转录、表达间的相互关系。方法以自身配对法收集肝癌的癌灶、癌周和远癌组织，以甲基化特异性PCR分析IGF—Ⅱ基因启动子P3的甲基化状态，以逆转录巢式PCR分析IGF-ⅡmRNA转录水平，以免疫组织化学法分析肝组织IGF-Ⅱ表达、胞内分布与临床病理学特征。对数据采用x2检验、等级相关等分析。结果IGF-Ⅱ基因B启动子甲基化率在肝癌组织为0，显著低于癌旁组织（47．5％，x2=24．918，P〈0．01）及远癌组织（100．0％，x2=80．000，P〈0．01）。肝癌组织IGF-ⅡmRNA扩增阳性率为100．0％，明显高于癌旁组织（52．5％，x2=24．918，P〈0．01）和远癌组织（0，x2=80．000，P〈0．01）；肝癌组织IGF-Ⅱ蛋白阳性表达率为82．5％，明显高于癌旁组织（45．0％，x2=12．170，P〈0．01）和远癌组织（0，x2=55．170，P〈0．01）。癌组织IGF-Ⅱ过表达与其分化程度、浆膜浸润、瘤体大小和HBV感染相关。结论基因表观遗传改变调控IGF-Ⅱ的转录和表达，与肝癌的发生、发展密切相关。

Objective To investigate whether epigenetic alterations in the insulin-like growth factor- Ⅱ （IGF-Ⅱ） gene that cause differential transcription or expression are correlated with onset and severity of hepatocellular carcinoma （HCC）. Methods Patient-matched specimens of HCC, paracancerous, and non-cancerous tissues were collected from 40 primary liver cancer patients. Epigenetic alterations in the promoter （P3） sequence of the IGF-Ⅱ gene were analyzed by methylation-specific PCR （MSP） and IGF- Ⅱ transcription was measured by RT-PCR. IGF-Ⅱ protein expression and clinicopathological features were assessed by immunohistochemistry and microscopic observation. Results The rate of IGF-Ⅱ P3 methylation was significantly lower in HCC tissues （0%） than in paracancerous tissues （vs. 47.5%; 2,2 =24.918, P〈0.001） tissues （vs. 100%;Z2= 80.000, P〈 0.001）. IGF-Ⅱ mRNA expression was significantly higher in HCC tissues （100%） than in paracancerous tissues （vs. 52.5%;x2=24.918, P〈0.001） and non-cancerous tissues （vs. 0% ;x2 = 80.000,P〈0.001）. IGF-Ⅱ protein expression was significantly higher in HCC tissues （82.5%） than in paracancerous tissues （vs. 45.0%;x2= 12.170,P〈0.001） and non-cancerous tissues （vs. 0%;x2= 56.170,P〈0.001）. IGF-Ⅱ overexpression in HCC was significantly associated with degree of differentiation, extent of infiltrated serosa, size of tumor, and HBV-positive infection status. Conclusion Epigenetic alterations in the IGF-Ⅱ gene regulate its transcription and expression and are closely associated with HCC development and progression.