LKB1通过HMGA2激活细胞自噬抑制肾癌侵袭迁移的作用机制研究

Accumulating evidence indicates that the tendency to invade and transfer is one of the obstacles for renal cell carcinoma (RCC) treatment, especially in the terminal RCC, due to the insensitivity to chemoradiotherapy and high likelihood of drug resistance for molecular targeted drugs. It is of great essential to explore the potential molecular mechanisms and interventions that targets for RCC invasion and metastasis. Our previous study demonstrated that the oncogene HMGA2 could promote migration, invasion and epithelial-mesenchymal transition (EMT) in RCC, while the protein kinase LKB1 significantly reversed EMT and downregulated the expression of HMGA2 in RCC. And chloroquine, an autophagy inhibitor, could partially abolish the inhibitory effect of LKB1 on the metastasis of RCC. In addition, the ectopic expression of LKB1 and HMGA2 could both regulate the expression of autophagy-related proteins LC3 and p62. Based on these features, we speculated that HMGA2-mediated autophagy may participate in the anti-metastatic effect of LKB1 on RCC. In our following study, we will focus on the anticancer efficacy and mechanisms of LKB1 on RCC migration and invasion, as well as cell autophagy via in-vitro assays and metastatic model in nude mice. Subsequently, we will demonstrate the potential mechanisms of autophagy in the inhibition of migration and invasion with the measure of autophagy regulators, to investigate the possibility of LKB1, HMGA2 and cell autophagy as the potential therapeutic targets for repressing RCC migration and invasion.

大量证据表明肾癌进程中易发侵袭转移，加之肾癌对放化疗不敏感，且分子靶向药物容易发生耐药，对生存期改善并不明显，一旦发生侵袭转移，将是肾癌尤其是晚期肾癌治疗的一大难题。因此探究肾癌侵袭转移的潜在分子机制及新的干预靶点显得尤为重要。我们的前期研究发现HMGA2这一癌基因可以促进肾癌细胞的侵袭迁移及上皮间质转化过程，而LKB1这一蛋白激酶则能抑制肾癌上皮间质转化并下调HMGA2表达，且LKB1抗肾癌侵袭迁移作用会被自噬抑制剂氯喹逆转。此外LKB1和HMGA2的异常表达均可调控自噬相关蛋白LC3和p62表达，因此我们推测HMGA2所介导的细胞自噬可能参与了LKB1抗肾癌侵袭迁移过程。本研究拟通过一系列体外实验和裸鼠肺转移模型探究LKB1抗肾癌侵袭迁移机制和调控细胞自噬机理，并利用自噬调节剂等探究细胞自噬抗肿瘤侵袭迁移的机理，以及LKB1、HMGA2、细胞自噬作为干预靶点用于抗肿瘤侵袭迁移的可能性。

侵袭转移是肾癌尤其是晚期肾癌治疗的一大难题，因此探究肾癌侵袭转移的潜在分子机制及新的干预靶点显得尤为重要。前期研究发现HMGA2可以促进肾癌细胞的侵袭迁移及上皮间质转化过程，而LKB1这一蛋白激酶则可以下调HMGA2表达。因此我们推测LKB1能够通过负向调控HMGA2抑制肾癌的侵袭迁移过程。本研究通过细胞划痕实验、transwell实验、实时定量PCR、western、数据库分析等多个实验发现：1）LKB1能够负向调控HMGA2抑制肾癌细胞的侵袭迁移及上皮间质转化，且FOXO4可能作为LKB1的上游调控子；2）基于cancer browser数据库发现HMGA2与肾癌的TNM分期、Stage分期呈正相关。且HMGA2在肾癌组织及细胞内呈高表达，并可以正向调控Twist1和Twist2的表达。3）Cancer browser数据库分析发现HMGA1的基因表达与肾癌的grade分级、stage分期以及TNM分期呈正相关关系，且差异具有统计学意义。而HMGA1可能是肾癌诊断和预后的一种潜在生物学标志物，高表达的HMGA1与肾癌患者的不良预后有关。4）LKB1通过正向调控SIK1抑制甲状腺癌的增殖、侵袭转移、血管新生。