The role of insulin-like growth factor binding protein-3 in the breast cancer cell response to DNA-damaging agents
The role of insulin-like growth factor binding protein-3 in the breast cancer cell response to DNA-damaging agents
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DOI：
10.1038/onc.2012.538
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发表时间：
2014-01-01
期刊：
影响因子：
8
通讯作者：
Baxter, R. C.
中科院分区：
文献类型：
--
作者：
Lin, M. Z.;Marzec, K. A.;Baxter, R. C.
在暴露于辐射和化学治疗剂之后，表皮生长因子受体（EGFR）可以通过形成包括DNA依赖性蛋白激酶（DNA-PKcs）的催化亚基的蛋白质复合物来调节DNA双链断裂（DSB）的修复。这是肿瘤对DNA损伤疗法产生抗性的关键机制之一。我们前期的研究表明，胰岛素样生长因子结合蛋白-3（IGFBP-3）是DNA-PKcs的底物，可以反式激活EGFR。因此，我们质疑IGFBP-3是否可能与调节DNA损伤反应的EGFR-DNA-PK复合物相互作用。本研究的目的是描述IGFBP-3在乳腺癌细胞对DSB诱导的化疗药物的反应中的作用。在雌激素受体阴性乳腺癌细胞系MDA-MB-468和Hs 578 T中，其高度表达IGFBP-3，EGFR和IGFBP-3的核定位通过细胞毒性药物依托泊苷或多柔比星处理而增强，并且通过EGFR激酶抑制剂吉非替尼而减少。IGFBP-3，EGFR和DNA-PKcs之间的增强关联，暴露于DNA损伤药物后，通过免疫共沉淀分析和直接可视化的邻位连接试验得到支持。在Ser 2056的DNA-PKcs的激活，通过非同源末端连接测定测量的DNA修复，以及由DNA损伤剂诱导的EGFR和DNA-PKcs相互作用的增加，都被IGFBP-3沉默降低，这表明IGFBP-3在DNA损伤治疗的DNA修复反应中具有强制性作用。总之，IGFBP-3共易位到乳腺癌细胞的细胞核，并与DNA-PKcs和EGFR在DNA损伤后形成复合物，表明其可能参与DNA修复的调节。这表明通过靶向IGFBP-3的DNA修复功能来使乳腺癌对化疗或放疗敏感的治疗方法的可能性。
Following exposure to radiation and chemotherapeutic agents, the epidermal growth factor receptor (EGFR) can modulate the repair of DNA double-strand breaks (DSB) by forming protein complexes that include the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs). This is one of the key mechanism by which tumors become resistant to DNA-damaging therapies. Our previous studies have shown that insulin-like growth factor binding protein-3 (IGFBP-3) is a substrate for DNA-PKcs, and can transactivate EGFR. We therefore questioned whether IGFBP-3 might interact with the EGFR - DNA-PK complex that regulates the DNA damage response. The aim of this study was to delineate the role of IGFBP-3 in the response of breast cancer cells to DSB-inducing chemotherapeutic agents. In the estrogen receptor-negative breast cancer cell lines MDA-MB-468 and Hs578T, which express IGFBP-3 highly, nuclear localization of EGFR and IGFBP-3 was enhanced by treatment with cytotoxic drugs etoposide or doxorubicin and reduced by the EGFR kinase inhibitor gefitinib. Enhanced association among IGFBP-3, EGFR and DNA-PKcs, following the exposure to DNA-damaging drugs was supported by both co-immunoprecipitation analysis and direct visualization by proximity ligation assay. The activation of DNA-PKcs at Ser2056, DNA repair as measured by a nonhomologous end-joining assay, and the increase in EGFR and DNA-PKcs interaction induced by DNA-damaging agents, were all decreased by IGFBP-3 silencing, suggesting that IGFBP-3 has an obligatory role in the DNA repair response to DNA-damaging therapy. In conclusion, IGFBP-3 co-translocation to the nucleus of breast cancer cells and its formation of a complex with DNA-PKcs and EGFR in response to DNA damage shows its potential involvement in the regulation of DNA repair. This suggests the possibility of a therapeutic approach for sensitizing breast cancer to chemo-or radiotherapy by targeting the DNA repair function of IGFBP-3.