RSK4靶向PI3K/AKT通路调控ACTN4在乳腺癌化疗耐药中的机制研究

Currently，Chemotherapy-resistant research about breast cancer is the focus. In our previous study, we found that RSK4 is closely related to the development of breast cancer. In the retrospective analysis, we found that the expression level of RSK4 is related to the sensitivity of neoadjuvant chemotherapy, and the low expression of RSK4 is ineffective in chemotherapy. We up-regulate RSK4 expression in breast cancer, ACTN4 expression decreased, and increased sensitivity to chemotherapeutic drugs. Down-regulation of RSK4 expression, the sensitivity decreased. In addition, we found that both RSK4 and ACTN4 are involved in the PI3K / AKT pathway. Therefore, we hypothesize that RSK4 modulate ACTN4 regulating chemo-resistance of breast cancer by targeting the PI3K / AKT pathway. This study intends to build breast cancer drug-resistant subtypes, and build lentiviral vector up-regulates or down-regulates the expression of RSK4, explore the sensitivity of RSK4 expression level to specific chemotherapeutic drugs via in vitro and in vivo experiments. Follows, the related core protein expression of PI3K / AKT pathway was detected by western blotting. We further verify the interaction between RSK4 and ACTN4 in vitro and in vivo experiments and explore the relationship between ACTN4 and neoadjuvant chemotherapy. We hope to find a new target for the resistance of breast cancer chemotherapy through this experiment.

乳腺癌化疗耐药研究已是当前研究热点。我们在前期研究中明确了RSK4与乳腺癌发生发展密切相关。在大数据回顾分析中，我们发现RSK4表达水平与新辅助化疗敏感性有关，RSK4表达低者化疗效果欠佳。我们在乳腺癌细胞中上调RSK4的表达，ACTN4表达降低，对化疗药物敏感性增加。下调RSK4的表达，则敏感性降低。另外，我们发现RSK4、ACTN4均与PI3K/AKT通路有关。因此，我们推测RSK4是通过靶向PI3K/AKT通路调控ACTN4影响乳腺癌化疗耐药的。本课题拟构建乳腺癌耐药亚型，构建慢病毒载体上调及下调RSK4的表达，通过体内外实验探究RSK4表达水平对具体化疗药物的敏感性，再研究PI3K/AKT通路相关核心蛋白的表达进行机制研究。进一步验证RSK4与ACTN4的相互作用关系，体内外实验探究ACTN4与新辅助化疗的关系。希望通过本次实验寻找作用于乳腺癌化疗耐药的新靶点。

乳腺癌是常见的女性恶性肿瘤之一，然而化疗耐药仍然是乳腺癌治疗过程的主要障碍，耐药形成过程中的关键基因尚不清楚。本研究旨在探讨核糖体S6蛋白激酶4（RSK4）在调节乳腺癌耐药性中的作用及其可能机制。我们首先使用生物信息学分析RSK4对乳腺癌患者预后及化疗的影响。构建并测定了乳腺癌耐药细胞，随后在耐药细胞中使用慢病毒上调RSK4的表达，采用CCK-8、划痕实验及Transwell实验检测RSK4对细胞耐药性的影响及作用通路，通过裸鼠移植瘤实验进一步验证了RSK4与乳腺癌耐药性的关系，接着通过细胞功能回复实验探究RSK4的作用靶点。最后采用免疫组化方法探讨乳腺癌组织中RSK4与α-辅肌动蛋白4（ACTN4）表达的关系。结果表明，RSK4与乳腺癌患者的生存率呈正相关，过表达RSK4能够减弱乳腺癌化疗耐药，抑制细胞迁移侵袭及肿瘤生长。临床病理分析显示，在人乳腺癌样本中，RSK4的表达与ACTN4呈负相关。综上所述，RSK4可通过抑制PI3K/AKT信号通路有效减弱乳腺癌对阿霉素的抗性，RSK4的高表达降低了乳腺癌中的紫杉醇耐药性，ACTN4是其可能的作用靶点。我们的发现为乳腺癌化疗耐药的潜在机制及治疗方法提供了新的视角。