SOX1通过调控ATP6L参与肺癌细胞转移及顺铂耐药的研究

Previously, we found that SOX1 which was downregulated in lung cancer played an important role in metastasis and cisplatin resistance in lung cancer. However,the underling mechanism remains unkown. The acidic tumor microenvironment has been proven to play crucial roles in cancer, including tumor chemotherapy resistance and metastasis. We also found that the expression of SOX1 was inhibited by acidic tumor microenvironment, and the inhibition of SOX1 in turn inhibited the expression of ATP6L, which was an important subunit of V-ATPase. It was reported that ATP6L was implicated in the formation and maintenance of acidic tumor microenvironment. On the basis of the results we obtained, we hypothesized that the expression of ATP6L was upregulated in lung cancer because of the low level of SOX1, the formation and maintenance of acidic tumor microenvironment was enhanced by the upregulation of ATP6L, in turn inhibited the expression of SOX1. There was a positive feedback between acidic tumor microenvironment and SOX1 inhibition, which was involved in the metastasis and cisplatin resistance in lung cancer.To test this hypothesis, we will test the effect of acidic tumor microenvironment on metastasis and cisplatin resistance of lung cancer in vitro and in vivo. Whether the expression of ATP6L was directly regluated by SOX1 and the manipulation of acidic tumor microenvironment by SOX1 was ATP6L-dependent also wii be explored in our work. Our work indicated that SOX1 may play an important role in metastasis and cisplatin resistance of human lung cancer, and targeting sox1 may be a promising therapeutic strategy against human lung cancer.

我们前期研究发现SOX1在肺癌细胞中低表达，其在肺癌细胞转移及顺铂耐药方面发挥重要作用，但具体机制尚不完全清楚。肿瘤酸性微环境与化疗药物耐药及转移密切相关。预实验显示酸性微环境抑制肺癌细胞SOX1表达；抑制SOX1促进ATP6L表达，而过表达SOX1则抑制ATP6L 的表达。ATP6L是V-APTase的亚基之一，其参与肿瘤酸性微环境的形成及维持。根据预实验结果我们提出假说：肺癌细胞中SOX1低表达，ATP6L因缺少SOX1抑制而表达升高，进而促进周围酸性微环境的形成及维持，酸性微环境则进一步抑制SOX1的表达，肿瘤酸性微环境与SOX1低表达形成正反馈；肿瘤酸性微环境则促进肺癌细胞转移及顺铂耐药。为验证该假说，我们首先通过体外、体内实验检测酸性微环境对肺癌细胞细胞转移及顺铂耐药的影响；探讨SOX1是否直接调控ATP6L的表达，SOX1调控酸性微环境是否是ATP6L依赖性的。

我们前期研究发现SOX1在肺癌细胞中低表达，其在肺癌细胞转移及顺铂耐药方面发挥重要作用，但具体机制尚不完全清楚。肿瘤酸性微环境与化疗药物耐药及转移密切相关。预实验显示酸性微环境抑制肺癌细胞SOX1表达；抑制SOX1促进ATP6L表达，而过表达SOX1抑制ATP6L 的表达。ATP6L是调控细胞外酸性微环境的关键蛋白。根据预实验结果我们提出假说：肺癌细胞中SOX1低表达，ATP6L因缺少SOX1抑制而表达升高，进而促进周围酸性微环境的形成及维持。我们通过体外、体内实验检测酸性微环境对肺癌细胞细胞转移及顺铂耐药的影响；探讨SOX1是否直接调控ATP6L的表达；探讨SOX1参与肺癌细胞转移的机制。.我们的结果提示酸性微环境可抑制SOX1的表达，其主要机制为酸性微环境促进SOX1启动子发生甲基化。另外发现酸性微环境促进肺癌细胞形态变化。尽管抑制SOX1表达可促进ATP6L的表达，然而我们发现过表达SOX1后细胞外酸性环境没有变化，说明SOX1可能无调控酸性微环境的能力，也可能是调控细胞外pH复杂，单一SOX1可能作用微弱。同时我们发现过表达SOX1可抑制肺癌细胞迁移和血管生成。通过基因芯片筛选出IGFBP1是SOX1下游重要靶基因。后续实验我们证实过表达SOX1可以抑制IGFBP1的表达，而抑制SOX1可以促进IGFBP1的表达。IGFBP1是细胞分泌因子，可以通过自分泌或旁分泌调控血管生成。我们发现过表达IGFBP1可以促进MIF的表达。MIF是重要的炎症因子，可以促进细胞血管生成、促进细胞迁移等。过表达SOX1可通过抑制IGFBP1/MIF表达，而IGFBP1/MIF均参与血管生成，两者受抑制后肺癌细胞血管生成也因此受到抑制；体内实验证实过表达SOX1可以抑制肺癌细胞在裸鼠肺内转移，而过表达IGFBP1可以逆转SOX1抑制的肺癌细胞裸鼠肺内转移；我们发现过表达SOX1可以抑制肺癌细胞骨转移，而IGFBP1过表达后可以促进肺癌细胞骨转移。总之，SOX1可以通过抑制IGFBP1表达参与抑制血管生成、抑制肺癌细胞转移以及参与抑制肺癌骨转移。通过对SOX1功能的研究，为今后肺癌的抗血管生成治疗，以及抗肺癌骨转移治疗等方面提供理论依据。