自噬相关基因5在肝癌组织中的表达及临床意义

背景与目的：肝细胞癌（hepatocellular carcinoma，HCC）是死亡率极高的原发性肝癌，其恶变的机制目前尚未明确。近些年随着对自噬研究的深入，发现自噬可以提供肿瘤生长高能量的需求，增加肿瘤细胞对极端低氧、化疗药物等环境的适应性，因而与肿瘤的恶性进程关系密切。该研究旨在探讨自噬小体形成中泛素样连接系统Atgl2-Atg5-Atgl6参与自噬的关键因子，自噬相关基因5（autophagy-related gene 5，Atg5）在HCC组织中的表达及与临床病理参数的关系。方法：回顾性分析中国医科大学肿瘤医院于2015年3月—2017年6月进行肝癌手术切除的110例已确诊无误的HCC标本，免疫组织化学染色检测110例癌旁及HCC组织中Atg5蛋白的表达，同时分析HCC组织中Atg5蛋白表达与患者临床病理学特征之间的关系。蛋白质印迹法（Western blot）与实时荧光定量聚合酶链反应（real-time fluorescent quantitative polymerase chain reaction，RTFQ-PCR）分别检测46例癌旁和HCC组织中Atg5蛋白及mRNA的表达。结果：免疫组织化学结果显示，HCC组织Atg5蛋白的阳性率71.82%（79/110），明显高于癌旁组织的阳性率20.09%（23/110）,差异有统计学意义（P<0.05）。HCC组织Atg5蛋白水平与肿瘤直径、甲胎蛋白（alpha fetoprotein，AFP）及血管侵犯相关（P<0.05），肿瘤直径大于等于5 cm、AFP水平大于等于200 ng/mL且合并血管侵犯HCC患者的Atg5蛋白水平较高。Western blot结果显示，HCC组织Atg5蛋白水平为1.25±0.25，癌旁组织为0.47±0.12（P<0.05）。RTFQ-PCR结果显示，Atg5 mRNA在HCC组织中的表达相当于癌旁组织的4.37倍（P<0.05）。结论：HCC组织中Atg5的基因表达和蛋白水平均显著增加，HCC组织的发生、发展可能与Atg5自噬活性的激活有关。

Expression of autophagy-related gene 5 in hepatocellular carcinoma and its clinical significance

Background and purpose: Hepatocellular carcinoma (HCC) is a primary liver cancer with extremely high mortality, and the mechanism of its malignant transformation is not yet clear. In recent years, with the deep research on autophagy, it has been found that autophagy can ensure the high energy demand of tumor growth and increase the adaptability of tumor cells to extreme hypoxia and chemotherapeutic drugs. Thus autophagy is closely related to the malignant process of the tumor. The aim of this study was to investigate the expression of autophagyrelated gene 5 (Atg5) in the ubiquitous connection system Atgl2-Atg5-Atgl6 in HCC and its relationship with clinicopathological parameters. Methods: HCC and adjacent tissues from 110 patients treated in Cancer Hospital of China Medical University from March 2015 to June 2017 were collected retrospectively. The immunohistochemical staining method was used to detect the expression of Atg5 protein in these HCC and adjacent tissues. Moreover, we analyzed the relationship between Atg5 protein expression and clinicopathological parameters in HCC tissues. Western blot and real-time fluorescent quantitative polymerase chain reaction (RTFQ-PCR) were used to detect the expression of Atg5 protein and its mRNA in 46 of 110 patients’ HCC and adjacent tissues. Results: The immunohistochemical results showed that the positive rate of Atg5 protein in HCC tissues was 71.82% (79/110), which was significantly higher than that in adjacent tissues ［20.09% (23/110), P<0.05］. The expression of Atg5 protein in HCC tissues was correlated with tumor size, alpha fetoprotein (AFP) level and vascular invasion (P<0.05). Furthermore, when clinicopathological parameters in HCC tissues were tumor size ≥5 cm, AFP level ≥200 ng/mL and combined with vascular invasion, the positive rate of Atg5 protein expression was higher. The expression of Atg5 protein was 1.25±0.25 in HCC tissues, and 0.47±0.12 in the adjacent tissues. The expression of Atg5 protein in HCC tissues was higher than that in adjacent tissues (P<0.05). RTFQ-PCR results showed that the relative expression level of Atg5 mRNA in HCC was 4.37 times that of the adjacent tissues (P<0.05). Conclusions: The gene expression and protein level of Atg5 in HCC is significantly increased. Furthermore, the activation of Atg5 may be closely related to the occurrence and development of HCC tissues.