Pathology Center, Shanghai First People's Hospital / Faculty of Basic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, PR China.
Pathology Center, Shanghai First People's Hospital / Faculty of Basic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, PR China.
Gene. 2014 Mar 10;537(2):238-44. doi: 10.1016/j.gene.2013.12.061. Epub 2014 Jan 8.
XPF/ERCC1 endonuclease is required for DNA lesion repair. To assess effects of a C2169A nonsense mutation in XPF at position 2169 in gastric cancer tissues and cell lines, genomic DNA was extracted from blood samples of 488 cancer patients and 64 gastric tumors. The mutation was mapped using a TaqMan MGB probe. In addition, gastric cancer cell lines were transfected with mutated XPF to explore XPF/ERCC1 interaction, XPF degradation, and DNA repair by a comet assay. The C2169A mutation was not detected in 488 samples of blood genomic DNA, yet was found in 32 of 64 gastric cancer tissue samples (50.0%), resulting in a 194C-terminal amino acid loss in XPF protein and lower expression. Laser micro-dissection confirmed that this point mutation was not present in surrounding normal tissues from the same patients. The truncated form of XPF (tXPF) impaired interaction with ERCC1, was rapidly degraded via ubiquitination, and resulted in reduced DNA repair. In gastric cancers, the mutation was monoallelic, indicating that XPF is a haplo-insufficient DNA repair gene. As the C2169A mutation is closely associated with gastric carcinogenesis in the Chinese population, our findings shine light on it as a therapeutic target for early diagnosis and treatment of gastric cancer.
XPF/ERCC1 内切酶是 DNA 损伤修复所必需的。为了评估胃癌组织和细胞系中 XPF 2169 位 C2169A 无义突变的影响，从 488 例癌症患者和 64 例胃癌肿瘤的血液样本中提取基因组 DNA。使用 TaqMan MGB 探针对突变进行定位。此外，通过彗星试验转染突变的 XPF 来探索 XPF/ERCC1 相互作用、XPF 降解和 DNA 修复。在 488 份血液基因组 DNA 样本中未检测到 C2169A 突变，但在 64 份胃癌组织样本中的 32 份（50.0%）中发现了该突变，导致 XPF 蛋白的 194 个 C 末端氨基酸缺失和表达水平降低。激光微切割证实该点突变不存在于同一患者的周围正常组织中。XPF 的截断形式（tXPF）与 ERCC1 的相互作用受损，通过泛素化迅速降解，导致 DNA 修复减少。在胃癌中，该突变是单等位基因的，表明 XPF 是一个杂合不足的 DNA 修复基因。由于 C2169A 突变与中国人群的胃癌发生密切相关，我们的研究结果表明它是早期诊断和治疗胃癌的治疗靶点。
