交叉反应物质197逆转卵巢癌紫杉醇耐药的作用与机制

Chemotherapy failure and high death rate are often attributed to resistance to chemotherapeutic agents, which has become a formidable problem in ovarian cancer.Cross-reacting material 197 (CRM197), an HB-EGF inhibitor, has been proven to significantly increases the sensitivity to paclitaxel in human ovarian carcinoma cells, but the machanism has not been sufficiently elucidated. Our study showed that CRM197 significantly reverses the resistance to paclitaxel in a paclitaxel-resistant human ovarian carcinoma cell line (A2780/Taxol), through regulating the expression of nucleus accumbens-1(NAC-1), a paclitaxel resistance-associated gene. This study will demonstrate that CRM197 contributes to paclitaxel resistance in ovarian cancer through the regulation of the NAC-1 pathway,including Gadd45gip1、Gadd45γ、P38MAPK/JNK ，in vitro and in vivo by ectopic expression and gene knockdown using transfection、real-time RT-PCR、Western blot、establishing tumor xenograft in nude mice and so on. Thus, this study will provide evidence for the study on CRM197 and shed light on the chemotherapy options for chemoresistant ovarian cancer patients.

紫杉醇治疗卵巢癌的耐药问题是关键难题。申请者前期研究发现交叉反应物质197（CRM197）作为肝素结合表皮生长因子（HB-EGF）的抑制剂，可调控耐药基因伏隔核因子1（NAC-1）而增强紫杉醇对癌细胞的杀伤作用。鉴于NAC-1可通过生长抑制DNA损伤基因45γ（Gadd45γ）及GADD45γ相互作用蛋白1（Gadd45gip1）调控与肿瘤细胞凋亡相关的MAPK信号通路，最终诱导卵巢癌的细胞凋亡。申请者推测CRM197逆转卵巢癌紫杉醇耐药作用的机制也与上述通路有关。本研究拟采用卵巢癌紫杉醇耐药细胞株A2780/Taxol探讨CRM197逆转其耐药的作用及相关信号通路；并在裸鼠接种耐药瘤株条件下加以验证；分别搜集紫杉醇敏感与耐药的卵巢癌组织标本，检测NAC-1表达水平并探讨其与紫杉醇耐药的相关性。本研究将创新性阐明CRM197逆转卵巢癌紫杉醇耐药机制，旨在为卵巢癌耐药患者的治疗提供新的思路。

紫杉醇耐药是卵巢癌治疗中的关键难题。我们的前期研究显示，交叉反应物质197（CRM197）可增强卵巢癌紫杉醇耐药细胞（A2780/Taxol）对紫杉醇的敏感性，并推测该作用与下调耐药基因伏隔核因子1（NAC-1）相关。在本课题中，我们验证这一发现并探讨CRM197下调NAC-1逆转耐药的作用机制。结果显示，CRM197可通过抑制A2780/Taxol细胞中NAC-1的表达水平促进NAC-1下游DNA损伤基因45（Gadd45）与GADD45相互作用蛋白1（Gadd45gip1）及丝裂原活化蛋白激酶激酶4（MEKK4）的表达，从而激活促凋亡信号通路JNK/p38MAPK诱导癌细胞凋亡，最终增强耐药细胞对紫杉醇的敏感性。本研究将为创新性阐明CRM197逆转卵巢癌紫杉醇耐药的作用与机制奠定重要基础，旨在为卵巢癌耐药患者的治疗提供新的思路。