Department of Surgical Oncology, Gifu University, Graduate School of Medicine, 1-1 Yanagido, Gifu, Gifu, 501-1194, Japan.
Gastric Cancer. 2013 Jul;16(3):345-54. doi: 10.1007/s10120-012-0191-0. Epub 2012 Sep 12.
Oxaliplatin is effective against many types of cancer, and the combination of 5-fluorouracil (5FU) and oxaliplatin is synergistically effective against gastric cancer, as well as colon cancer. The FANCJ protein is one of the Fanconi anemia (FA) gene products, and its interaction with the tumor suppressor BRCA1 is required for DNA double-strand break (DSB) repair. FANCJ also functions in interstrand crosslinks (ICLs) repair by linking to mismatch repair protein complex MLH1-PMS2 (MutLα). While oxaliplatin causes ICLs, 5FU is considered to cause DSBs. Therefore, we investigated the importance of FANCJ in the synergistic effects of oxaliplatin and 5FU in MKN45 gastric cancer cells and the derived 5FU-resistant cell line, MKN45/F2R.
MKN1, TMK1, MKN45, and MKN45/F2R (5FU-resistant) gastric cancer cells were treated with 5FU and/or oxaliplatin. The signaling pathway was evaluated by a western blotting analysis and reverse transcription polymerase chain reaction (RT-PCR). Drug resistance was evaluated by the 3-(4,5-dimethyl-2-tetrazolyl)-2,5-diphenyl-2H tetrazolium bromide (MTT) assay.
In MKN45 cells, the combination of 5FU and oxaliplatin had synergistic effects. DSBs appeared when the cells were treated with 5FU. FANCJ was down-regulated, and BRCA1 was induced in a dose- and time-dependent manner. MKN45 cells showed increased sensitivity to oxaliplatin when FANCJ was knocked down by short interfering (si) RNA. However, these findings were not observed in MKN45/F2R 5FU-resistant cells.
These results strongly suggest that the decrease in FANCJ caused by 5FU treatment leads to an increase in sensitivity to oxaliplatin, thus indicating that the FANCJ protein plays an important role in the synergism of the combination of 5FU and oxaliplatin.
奥沙利铂对多种类型的癌症有效，5-氟尿嘧啶（5FU）和奥沙利铂的联合应用对胃癌和结肠癌具有协同作用。FANCJ 蛋白是范可尼贫血（FA）基因产物之一，其与肿瘤抑制因子 BRCA1 的相互作用对于 DNA 双链断裂（DSB）修复是必需的。FANCJ 还通过与错配修复蛋白复合物 MLH1-PMS2（MutLα）连接来参与链间交联（ICLs）修复。虽然奥沙利铂引起 ICLs，5FU 被认为会引起 DSBs。因此，我们研究了 FANCJ 在奥沙利铂和 5FU 对 MKN45 胃癌细胞及其衍生的 5FU 耐药细胞系 MKN45/F2R 的协同作用中的重要性。
用 5FU 和/或奥沙利铂处理 MKN1、TMK1、MKN45 和 MKN45/F2R（5FU 耐药）胃癌细胞。通过 Western 印迹分析和逆转录聚合酶链反应（RT-PCR）评估信号通路。通过 3-（4,5-二甲基-2-四唑基）-2,5-二苯基-2H 四唑溴盐（MTT）测定评估耐药性。
在 MKN45 细胞中，5FU 和奥沙利铂联合应用具有协同作用。用 5FU 处理时出现 DSBs。FANCJ 下调，BRCA1 呈剂量和时间依赖性诱导。用短发夹 RNA（siRNA）敲低 FANCJ 时，MKN45 细胞对奥沙利铂的敏感性增加。然而，在 5FU 耐药的 MKN45/F2R 细胞中未观察到这些发现。
这些结果强烈表明，5FU 处理导致 FANCJ 的减少导致对奥沙利铂的敏感性增加，因此表明 FANCJ 蛋白在 5FU 和奥沙利铂联合应用的协同作用中发挥重要作用。
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