Wiltshire Timothy, Senft Jamie, Wang Yutian, Konat Gregory W, Wenger Sharon L, Reed Eddie, Wang Weixin
Department of Microbiology, Immunology and Cell Biology, West Virginia University School of Medicine, Morgantown, WV 26506-9300, USA.
Mol Pharmacol. 2007 Apr;71(4):1051-60. doi: 10.1124/mol.106.029504. Epub 2007 Jan 17.
Tumor suppressor gene BRCA1 is frequently mutated in familial breast and ovarian cancer. BRCA1 plays pivotal roles in maintaining genomic stability by interacting with numerous proteins in cell cycle control and DNA repair. Irofulven (6-hydroxymethylacylfulvene, HMAF, MGI 114, NSC 683863) is one of a new class of anticancer agents that are analogs of mushroom-derived illudin toxins. Preclinical studies and clinical trials have demonstrated that irofulven is effective against several tumor cell types. The exact nature of irofulven-induced DNA damage is not completely understood. We demonstrated previously that irofulven activates ATM and its targets, NBS1, SMC1, CHK2, and p53. In this study, we hypothesize that irofulven induces DNA double-strand breaks and that BRCA1 may affect chemosensitivity by controlling cell cycle checkpoints, DNA repair, and genomic stability in response to irofulven treatment. We observed that irofulven induces the formation of chromosome breaks and radials and the activation and foci formation of gamma-H2AX, BRCA1, and RAD51. We also provided evidence that irofulven induces the generation of DNA double-strand breaks. By using BRCA1-deficient or -proficient cells, we demonstrated that in response to irofulven, BRCA1 contributes to the control of S and G(2)/M cell cycle arrest and is critical for repairing DNA double-strand breaks and for RAD51-dependent homologous recombination. Furthermore, we found that BRCA1 deficiency results in increased chromosome damage and chemosensitivity after irofulven treatment.
肿瘤抑制基因BRCA1在家族性乳腺癌和卵巢癌中经常发生突变。BRCA1通过与细胞周期调控和DNA修复中的多种蛋白质相互作用，在维持基因组稳定性方面发挥关键作用。伊洛福芬（6-羟甲基酰基富烯，HMAF，MGI 114，NSC 683863）是一类新型抗癌药物，是蘑菇衍生的隐杯伞毒素类似物。临床前研究和临床试验表明，伊洛福芬对几种肿瘤细胞类型有效。伊洛福芬诱导DNA损伤的确切性质尚未完全了解。我们之前证明伊洛福芬可激活ATM及其靶点NBS1、SMC1、CHK2和p53。在本研究中，我们假设伊洛福芬诱导DNA双链断裂，并且BRCA1可能通过控制细胞周期检查点、DNA修复和基因组稳定性来影响对伊洛福芬治疗的化学敏感性。我们观察到伊洛福芬诱导染色体断裂和放射状形成以及γ-H2AX、BRCA1和RAD51的激活和灶形成。我们还提供证据表明伊洛福芬诱导DNA双链断裂的产生。通过使用BRCA1缺陷或正常的细胞，我们证明，在对伊洛福芬的反应中，BRCA1有助于控制S期和G(2)/M期细胞周期停滞，对于修复DNA双链断裂和RAD51依赖的同源重组至关重要。此外，我们发现BRCA1缺陷导致伊洛福芬治疗后染色体损伤增加和化学敏感性增加。
