Department of Oral Medicine, The Second Hospital of Hebei Medical University, Heping Western Road 215, Shijiazhuang, Hebei, 050000, People's Republic of China.
Department of Thoracic Surgery, Tianjin Union Medical Center, 190 Jieyuan Road, Hongqiao District, Tianjin, Tianjin, 300121, People's Republic of China.
Clin Oral Investig. 2017 Nov;21(8):2535-2542. doi: 10.1007/s00784-017-2052-z. Epub 2017 Jan 13.
The study aimed to evaluate the methylation pattern of the interferon-gamma (IFN-γ) gene in oral cancer tissues compared with normal and benign oral disease tissues.
The oral tissues were gained from the patients of 85 cases of oral squamous cell carcinoma (OSCC), 47 cases of oral dysplastic lesions, and 53 normal biopsies. IFN -γ methylation in oral tissues was verified through methylation-specific polymerase chain reaction (PCR) and DNA sequencing analyses, and the expression levels of IFN-γ messenger RNA (mRNA) and protein were detected using real-time reverse transcription (RT)-PCR and enzyme-linked immunosorbent assays, respectively. IFN-γ was localized in macrophages from oral tissues and detected via immunostaining.
IFN-γ mRNA and protein expression levels were evidently decreased in oral cancer tissues, whereas the IFN-γ methylation rate was significantly higher in malignant tumors than in benign and normal tissues (normal, 22.6%; benign, 38.3%; and cancer, 55.3%; P < 0.05). Furthermore, the expression of IFN-γ mRNA was significantly downregulated in oral tumors with methylation compared with tumors without methylation, as determined by real-time RT-PCR (4.76-fold difference; P < 0.05). Likewise, mRNA expression was downregulated by 6.79-fold in oral epithelial dysplasia tissues with methylation compared with those without methylation (P < 0.01). Co-immunostaining to detect MAC2 and IFN-γ demonstrated that macrophages comprised the main source of IFN-γ in oral tissues. IFN-γ methylation demonstrated a significant association with the clinical stage, histopathology grade, and primary tumor.
Aberrant IFN-γ promoter methylation may be involved in the process of tumorigenesis of oral cancer.
IFN-γ hypermethylation during the process of oral carcinogenesis could be useful for the clinical diagnosis and treatment for OSCC.
本研究旨在评估干扰素-γ（IFN-γ）基因在口腔癌组织中的甲基化模式，并与正常和良性口腔疾病组织进行比较。
从 85 例口腔鳞状细胞癌（OSCC）、47 例口腔发育不良病变和 53 例正常活检患者中获得口腔组织。通过甲基化特异性聚合酶链反应（PCR）和 DNA 测序分析验证 IFN-γ 甲基化，使用实时逆转录（RT）-PCR 和酶联免疫吸附试验分别检测 IFN-γ信使 RNA（mRNA）和蛋白的表达水平。通过免疫染色检测 IFN-γ在口腔组织中的巨噬细胞中的定位。
在口腔癌组织中，IFN-γ mRNA 和蛋白表达水平明显降低，而恶性肿瘤中的 IFN-γ 甲基化率明显高于良性和正常组织（正常组织为 22.6%；良性组织为 38.3%；恶性肿瘤为 55.3%；P<0.05）。此外，通过实时 RT-PCR 发现，与无甲基化肿瘤相比，甲基化肿瘤中 IFN-γ mRNA 的表达明显下调（差异倍数为 4.76；P<0.05）。同样，在有甲基化的口腔上皮发育不良组织中，mRNA 表达下调了 6.79 倍（P<0.01）。共同免疫染色检测 MAC2 和 IFN-γ 表明，巨噬细胞是口腔组织中 IFN-γ 的主要来源。IFN-γ 甲基化与临床分期、组织病理学分级和原发肿瘤显著相关。
异常 IFN-γ 启动子甲基化可能参与了口腔癌的肿瘤发生过程。
在口腔癌发生过程中，IFN-γ 高甲基化可能有助于 OSCC 的临床诊断和治疗。
