ATM介导的ARID1A磷酸化在宫颈癌抑制性免疫微环境形成中的作用及机制研究

Evidences have shown that loss of ARID1A gene expression in the cervical cancer is associated with malignant progression of the cancer. But the molecular mechanism involved in ARID1A function loss and its tumor suppressor function remain to be elucidated. Previously we found that ATM interacts with ARID1A and inhibits its function in gene transcription regulation. we also found that ARID1A binds to the promoter of IRF2 and LDHA and regulates their transcription. Moreover, we found that down-regulation of ARID1A in cervical cancer cells can increase PD-L1 expression in cervical cancer cells and impair the response of cervical cancer cells to PD-L1 blockade. In this study, we will further investigate that ARID1A is phosphorylated by ATM and subsequently impaired its function on transcription regulation, which may be an important mechanism of ARID1A function loss in the cervical cancer. We will explore that ARID1A enhance immune surveillance through upregulation of IRF2 and downregulation of LDHA via SWI/SNF mediated chromatin remodeling activity which is an important mechanism of ARID1A tumor suppressor function. We will also confirm that DNA damage activated ATM can increase PD-L1 expression and lactate production by impairing the transcription regulation of ARIDIA on IRF2 and LDHA, which may be the critical mechanism of inhibition of cell immunity and development of suppressing immune microenvironment in cervical cancer following the radiochemotherapy. This study will help to discover new promising therapeutic approach for the treatment of cervical cancer.

研究显示ARID1A在宫颈癌中功能缺失并与恶性进展相关但机制不清楚。前期研究发现宫颈癌细胞中ATM与ARID1A有互作并抑制ARID1A转录调控功能；ARID1A敲低能上调细胞PD-L1表达和降低PD-L1阻断剂疗效；ARID1A结合在IRF2和LDHA启动子并调控它们转录。本项目拟在此基础上从分子、细胞、组织和动物水平：阐明ATM磷酸化ARID1A的DNA结合域及其导致的ARID1A DNA结合功能丧失是宫颈癌中ARID1A功能缺失的重要机制；确定ARID1A通过SWI/SNF染色质重塑活性上调IRF2和下调LDHA表达来增强机体免疫监视能力是ARID1A抑制宫颈癌的机制之一；阐明放化疗激活的ATM通过抑制ARID1A转录调控活性，导致IRF2和LDHA表达变化，进而促进PD-L1表达和乳酸分泌，从而导致宫颈癌抑制性免疫微环境形成。该研究将为宫颈癌新的治疗靶标发现提供理论基础和实验依据。

宫颈癌是妇科生殖系统最常见恶性肿瘤，严重影响妇女身心健康，但其发病机制尚不清楚。晚期宫颈癌治疗效果不佳，ICIs治疗为患者带来希望，但大多数患者存在治疗抵抗，其分子机理尚未阐明。大量研究发现ARID1A功能缺失与颈癌发生发展以及放化疗耐受密切相关，但在宫颈癌中影响ARID1A功能的机制以及其下游的促癌分子网络尚未完全阐明。我们前期研究发现在宫颈癌细胞中ATM与ARID1A相互结合并能磷酸化ARID1A 1065位苏氨酸；通过ChIP-seq检测发现ARID1A结合在IRF2和LDHA启动子并调控该两基因转录。在此基础上，本项目在宫颈癌组织中发现ATM和1065T 磷酸化ARID1A显著上调，且两者在癌组织中呈现显著的正相关性；pARID1A在癌组织中量与患者的临床分期、局部浸润、生存期和免疫抑制性微环境显著相关。在分子和细胞水平证实ATM磷酸化ARID1A1065T后导致ARID1A与靶基因启动子DNA结合能力降低，丧失染色质重塑功能。本项目进一步从分子、细胞和组织水平证实了宫颈癌中存在ATM/ARID1A/LDHA/乳酸和ATM/ARID1A/IRF2/PD-L1这两条新的信号通路，这两条通路激活是宫颈癌免疫逃逸和ICIs治疗抵抗的重要分子机制。通过本项目的研究我们发现了宫颈癌中ARID1A功能的调控机制和ARID1A抑制宫颈癌的分子机理，这为提高宫颈癌ICIs治疗效果提供了新的靶点，为宫颈癌患者精准免疫治疗提供新的分选标志物。