Production of truncated MBD4 protein by frameshift mutation in DNA mismatch repair-deficient cells enhances 5-fluorouracil sensitivity that is independent of hMLH1 status.
Production of truncated MBD4 protein by frameshift mutation in DNA mismatch repair-deficient cells enhances 5-fluorouracil sensitivity that is independent of hMLH1 status.
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DNA 错配修复缺陷细胞中通过移码突变产生截短的 MBD4 蛋白可增强 5-氟尿嘧啶敏感性，且与 hMLH1 状态无关。
DOI：
10.1080/15384047.2016.1178430
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发表时间：
2016
影响因子：
3.6
通讯作者：
Carethers,JohnM
中科院分区：
文献类型：
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作者：
Suzuki,Satoshi;Iwaizumi,Moriya;Tseng-Rogenski,Stephanie;Hamaya,Yasushi;Miyajima,Hiroaki;Kanaoka,Shigeru;Sugimoto,Ken;Carethers,JohnM
甲基cpg结合结构域蛋白4 （MBD4）是一种DNA糖基化酶，可以去除DNA中的5-氟脱氧尿嘧啶，并修复T:G或U:G错配。MBD4是DNA错配修复（MMR）缺陷移码突变的靶标，导致MBD4蛋白（TruMBD4）缺失其糖基化酶结构域。本研究表明，TruMBD4在增强5-氟尿嘧啶（5FU）在mmr缺陷结肠直肠癌细胞中的敏感性中起重要作用。我们从生化角度发现，TruMBD4与5FU结合到DNA中的亲和力高于MBD4。TruMBD4降低了先前报道中决定5FU敏感性的MMR识别复合物的5FU亲和力，这表明其他机制可能是触发细胞毒性的有效机制。为了分析TruMBD4对5FU的总体敏感性，我们在使用5FU治疗后，在hmlh1精通或缺乏的结直肠癌细胞中建立了TruMBD4过表达。与对照组相比，5fu处理的TruMBD4细胞表现出生长特性降低，与hmlh1status无关。流式细胞术显示5fu处理的TruMBD4细胞处于S期的数量多于对照组。我们得出结论，mmr缺陷癌症患者对5FU治疗表现出特征性的耐药性，可能是通过碱基切除修复基因embd4的继发性移码突变增加了5FU敏感性。
Methyl-CpG binding domain protein 4 (MBD4) is a DNA glycosylase that can remove 5-fluorodeoxyuracil from DNA as well as repair T:G or U:G mismatches.MBD4is a target for frameshift mutation with DNA mismatch repair (MMR) deficiency, creating a truncated MBD4 protein (TruMBD4) that lacks its glycosylase domain. Here we show that TruMBD4 plays an important role for enhancing 5-fluorouracil (5FU) sensitivity in MMR-deficient colorectal cancer cells. We found biochemically that TruMBD4 binds to 5FU incorporated into DNA with higher affinity than MBD4. TruMBD4 reduced the 5FU affinity of the MMR recognition complexes that determined 5FU sensitivity by previous reports, suggesting other mechanisms might be operative to trigger cytotoxicity. To analyze overall 5FU sensitivity with TruMBD4, we established TruMBD4 overexpression inhMLH1-proficient or -deficient colorectal cancer cells followed by treatment with 5FU. 5FU-treated TruMBD4 cells demonstrated diminished growth characteristics compared to controls, independently ofhMLH1status. Flow cytometry revealed more 5FU-treated TruMBD4 cells in S phase than controls. We conclude that patients with MMR-deficient cancers, which show characteristic resistance to 5FU therapy, may be increased for 5FU sensitivity via secondary frameshift mutation of the base excision repair geneMBD4.