微小RNA-302c/白细胞介素8通路调控胃癌曲妥珠单抗耐药的机制研究

Trastuzumab is the first molecular targeting drug applied to gastric cancer, and offers hope for gastric cancer patients in later stage. However, resistance to Trastuzumab is a "bottleneck" which seriously hinders further improvement on efficacy. Our previous studies revealed that microRNA (miR) -302c modulated invasion and metastasis of gastric cancer by inhibiting the expression of Interleukin-8 (IL8). Further studies showed that expression of miR-302c was down-regulated in Trastuzumab resistant cell line, while IL8 was up-regulated. On this basis, we hypothesis that miR-302c / IL8 axis involves in the regulation of Trastuzumab resistance in gastric cancer. Here we propose to firstly screen the key signaling pathway regulating expression of miR-302c / IL8 axis in Trastuzumab-resistant gastric cancer cell and then clarify the pivotal role of IL8 in resistance to Trastuzumab, including anti-apoptosis, maintaining stemness of cancer stem cell and pro-angiogenesis, through cellular experiments and patient’s sample studies. The value of inhibiting the expression or function of IL8 to reverse Trastuzumab resistance in gastric cancer will be explored afterwards, through combining the in vitro methods with in vivo animal model. We expect new ideas for targeting therapy and individualized treatment of gastric cancer can be provided.

曲妥珠单抗（Trastuzumab）是第一个应用于临床的胃癌靶向治疗药物，为晚期胃癌患者的治疗带来了希望，但随之而来的耐药问题却严重阻碍其疗效进一步提高。我们在前期研究中发现，微小RNA（miR）-302c可通过抑制白细胞介素-8（IL8）表达调节胃癌的侵袭转移。进一步研究表明，曲妥珠单抗耐药胃癌细胞株中，miR-302c表达下调，而IL8表达上调。在此基础上，我们提出miR-302c / IL8通路参与调节胃癌曲妥珠单抗耐药的假说。我们拟通过细胞实验筛选曲妥珠单抗耐药胃癌细胞株调节miR-302c / IL8表达的关键信号通路，并结合组织标本研究，从抗细胞凋亡、维持肿瘤干细胞干性、促血管生成等方面阐明IL8参与胃癌曲妥珠单抗耐药的分子机制。进而通过细胞实验和动物模型研究，探讨抑制IL8表达或功能以逆转胃癌曲妥珠单抗耐药的应用价值，以期为胃癌的靶向治疗和个体化治疗提供新的思路。

曲妥珠单抗（Trastuzumab）是第一个应用于临床的胃癌靶向治疗药物，为晚期胃癌患者的治疗带来了希望，但随之而来的耐药问题严重阻碍其疗效进一步提高。我们在本项目研究中，发现胃癌组织和胃癌细胞中HER2与IL8表达呈负相关性。然后通过建立曲妥珠单抗耐药胃癌细胞株，发现耐药细胞株中IL8的表达和分泌明显上调，miR-302c表达明显下调。进而证明胃癌细胞中miRNA-302可以IL8为靶标，并抑制其表达。继而使用曲妥珠单抗联合IL8中和性抗体或IL8受体特异性抑制剂处理胃癌曲妥珠单抗耐药细胞，显著抑制了肿瘤细胞的增殖，诱导细胞凋亡，同时下调干细胞标志的表达。从而提示抑制IL8表达或功能可以做为逆转胃癌曲妥珠单抗耐药的一个策略。我们还建立了HER2阳性胃癌患者曲妥珠单抗敏感和耐药的裸鼠异种移植瘤（PDX）模型，筛选了参与胃癌曲妥珠单抗耐药的重要基因和信号通路，发现HER2下游信号通路的失活及DNA复制和细胞周期异常活化可能是HER2阳性胃癌发生曲妥珠单抗耐药的重要机制，为胃癌的靶向治疗和个体化治疗提供了新的思路。