Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
NHCPRC Key Laboratory of Combined Multi-Organ Transplantation, Hangzhou, China.
Clin Transl Oncol. 2020 Mar;22(3):392-400. doi: 10.1007/s12094-019-02140-9. Epub 2019 Jul 1.
Intrahepatic cholangiocarcinoma (ICC) is one of the most devastating cancers of the gastrointestinal tract. It is crucial to determine the accurate prognostic factors and find new therapeutic strategies. Meanwhile, O-methylguanine-DNA methyltransferase (MGMT) is associated with malignant tumor progression. Thus, further studies are needed to investigate whether MGMT plays a similar role in ICC.
Quantitative real-time PCR, western blot, and immunohistochemistry staining were used to detect the expression of MGMT in ICC tissues. The correlations between MGMT expression and clinicopathologic features were analyzed. The cell-proliferation assay and colony-formation assay were applied to evaluate proliferation ability, while methylation-specific PCR were used to detect the methylation status of the MGMT promoter CpG island in ICC tissues and cells.
Our study found that the expression of MGMT was decreased in ICC tissues when compared with paired normal tissues. In addition, we demonstrated that MGMT expression was positively correlated with overall survival rates and tumor histological grade. Silencing of MGMT significantly promoted cell proliferation in ICC. Further research showed that silencing of MGMT induced cells to enter S phase by inhibiting p21, p27, and Cyclin E expression, ultimately promoting ICC proliferation. We also demonstrated that the MGMT promoter was highly methylated in ICC, and the levels of MGMT and p21 mRNA increased after DNA demethylation. In addition, the levels of MGMT and p21 protein were positively correlated in ICC tissues.
MGMT may play a critical role in carcinogenesis and the development of ICC, and provides a new marker of clinical prognosis and target for ICC treatment.
肝内胆管癌（ICC）是胃肠道最具破坏性的癌症之一。确定准确的预后因素并寻找新的治疗策略至关重要。同时，O-甲基鸟嘌呤-DNA 甲基转移酶（MGMT）与恶性肿瘤进展有关。因此，需要进一步研究以探讨 MGMT 是否在 ICC 中发挥类似作用。
采用定量实时 PCR、western blot 和免疫组织化学染色检测 MGMT 在 ICC 组织中的表达。分析 MGMT 表达与临床病理特征的相关性。应用细胞增殖试验和集落形成试验评估增殖能力，甲基化特异性 PCR 检测 ICC 组织和细胞中 MGMT 启动子 CpG 岛的甲基化状态。
我们的研究发现，与配对的正常组织相比，MGMT 在 ICC 组织中的表达降低。此外，我们证明 MGMT 表达与总生存率和肿瘤组织学分级呈正相关。MGMT 沉默显著促进 ICC 细胞增殖。进一步的研究表明，MGMT 沉默通过抑制 p21、p27 和 Cyclin E 的表达使细胞进入 S 期，从而促进 ICC 增殖。我们还证明了 MGMT 启动子在 ICC 中高度甲基化，DNA 去甲基化后 MGMT 和 p21mRNA 的水平增加。此外，ICC 组织中 MGMT 和 p21 蛋白水平呈正相关。
MGMT 可能在 ICC 的发生和发展中发挥关键作用，为 ICC 的临床预后标志物和治疗靶点提供了新的依据。
