靶向抑制铜伴侣蛋白CCS逆转卵巢癌C13*细胞的顺铂耐药性

顺铂（cisplatin），即二胺二氯铂/diaminedichloroplatinum（DDP），是治疗卵巢癌最有效的化疗药物；然而，耐药性是限制顺铂临床治疗效果的最重要因素。目前，卵巢癌对顺铂的耐药机制仍不十分清楚。超氧化物歧化酶1铜伴侣蛋白（copper chaperone for superoxide dismutase 1, CCS）介导Cu2+特异性传递给超氧化物歧化酶1（superoxide dismutase1, SOD1），为维持细胞增殖和生存所必需；相反，抑制CCS可减缓肿瘤细胞增殖。本研究旨在证明，AMPK依赖的CCS表达与卵巢癌的顺铂耐药有关。实时定量PCR及免疫印迹结果显示，与顺铂敏感细胞株OV2008比较，顺铂耐药细胞株C13*中的CCS mRNA和蛋白质表达水平明显上调。shRNA靶向沉默CCS或采用抑制剂DC_AC50抑制CCS后，可明显增强顺铂对C13*细胞增殖的抑制作用，提示CCS高表达与顺铂耐药相关，而抑制CCS可逆转顺铂的耐药性。同样，免疫印迹结果证明，CCS在A549、H1944等6种不同肺癌细胞中的表达水平高低与顺铂敏感性密切相关。采用siRNA干扰CCS在A549细胞中的高表达，或在CCS低表达的H1944细胞中过表达CCS，可明显增加A549或减弱H1944细胞对顺铂的敏感性，进一步证明CCS表达与顺铂耐药性相关。此外，采用AMPK抑制剂化合物C阻断AMPKα Thr172磷酸化（激活），即抑制AMPK信号通路，可明显抑制CCS在C13*细胞中的表达，提高其对顺铂的敏感性。以上研究结果提示，AMPK信号通路依赖的CCS表达参与肿瘤的顺铂耐药机制，而抑制CCS逆转顺铂耐药。本文的结果还提示，CCS有望成为克服顺铂耐药的潜在靶点。

Inhibition of Copper Chaperone for Superoxide Dismutase 1 (CCS) Reverses Cisplatin Resistance in C13* Ovarian Cancer Cells

Cisplatin (also known as diaminedichloroplatinum, DDP) is currently one of the most effective chemotherapeutics for treatment of ovarian cancer. However, the resistance to DDP is a common obstacle. The mechanisms of DDP resistance are unclear. Copper chaperone for superoxide dismutase1 (CCS) mediates the transfer of Cu2+ to superoxide dismutase 1 (SOD1), thereby maintains cell proliferation and survival. Contrarily, inhibition of CCS can retard tumor cell proliferation. This study aims to demonstrate that AMPK dependent CCS expression is involved in ovarian cancer DDP resistance. Real time quantitative PCR (RT-qPCR) and Western blotting results showed that the levels of CCS mRNA and protein in DDP-resistant ovarian cancer C13* cells were markedly up-regulated when compared to that of DDP-sensitive OV2008 cells. Silencing CCS by shRNA or inhibiting CCS by the inhibitor DC_AC50 could significantly enhance DDP-inhibited proliferation of C13* cells, indicating that high expression of CCS is associated with DDP resistance, and suppression of CCS can reverse DDP resistance. Similarly, Western blotting results revealed that the levels of CCS in six lung cancer cells including A549 and H1944 were closely correlated to the sensitivities of cancer cells to DDP. Silencing CCS expression markedly increased DDP sensitivity of A549, while over expression of CCS decreased DDP sensitivity of H1944, which further demonstrated the correlation of CCS with DDP resistance. In addition, blocking the phosphorylation/activation of AMPKα at Thr172 by Compound C, an inhibitor of AMPK, could down-regulate CCS expression in C13* and enhance its sensitivity to DDP. These data suggest that AMPK signal-dependent CCS expression is involved in the mechanism of DDP resistance in cancers, and suppressing CCS reverses DDP resistance. These data also indicate that the CCS is hopeful to be a potential target for overcoming DDP resistance.