突触小体相关蛋白SNAP47促进肺腺癌侵袭转移的作用及机制研究

SNARE（Soluble NSF Attachment protein Receptors）complex–mediated vesicle trafficking, as the key process to re-modulate the ECM (extracellular matrix), has been shown to play a pivotal role in the regulation of the tumor invasion and metastasis. However, the underlying mechanisms remain largely unknown. In this study, we focus on Synaptosome associated protein 47 (SNAP 47), which is an important subunit of SNARE complex. Our preliminary data show that SNAP47 is highly expressed in lung adenocarcinoma (LAC). Elevated expression of SNAP47 is significantly associated with patients’ prognosis. Knockdown of SNAP47 inhibits invasion and migration of LAC cell line, and blocks the secretion of MMP2 and MMP14. Also, knockdown of SNAP47 may suppress the activation of the EGFR/PI3K/Akt pathway and inhibit the release of EGF. We therefore hypothesize that SNAP47 may promote the invasion and metastasis of LAC via both increasing the secretion of MMP2 and MMP14 as well as involving the establishment of a positive feedback loop to activate the EGFR pathway. In this study, we will further elucidate the molecular mechanisms whereby SNAP47 promotes the invasion and metastasis of LAC. We will also investigate the role of SNAP47 in the regulation of LAC invasion and metastasis in both mouse model and LAC patients. Our study may identify new potential therapeutic target for the treatment of LAC.

SNARE复合物介导的囊泡运输作为细胞外基质重塑的关键环节，已被证明在肿瘤的侵袭转移过程中发挥了至关重要的作用，但具体的分子机制并不明确。以此为切入点，针对SNAP47这一功能未知的SNARE亚基，我们开展了相关的前期工作。初步研究结果发现： SNAP47特异性高表达于肺腺癌组织，并与病人预后密切相关；沉默SNAP47的表达能够抑制肺腺癌细胞的增殖和侵袭能力，并导致MMP2和MMP14的胞内潴留；沉默SNAP47能够抑制EGFR/PI3K/Akt通路活性，同时导致EGF外排障碍。基于此我们提出：SNAP47可能通过增强肺腺癌细胞MMP2和MMP14的分泌，并参与EGFR正反馈循环的形成，最终促进肺腺癌的侵袭转移。本项目将深入研究SNAP47促进肺腺癌侵袭转移的分子机制，并结合实验动物和临床标本进一步研究SNAP47促进肺腺癌侵袭转移的作用。本研究的成功实施可为肺腺癌防治提供新靶标。

SNARE复合物介导的囊泡运输作为细胞外基质重塑的关键环节，已被证明在肿瘤的侵袭转移过程中发挥了至关重要的作用，但具体的分子机制并不明确。以此为切入点，针对SNAP47这一功能未知的SNARE亚基，课题组在临床肺腺癌标本中进行初步探索，结果表明SNAP47高表达的肺腺癌病人预后差，且与TNM分期相关，通过病人临床资料多因素分析发现SNAP47的表达可作为肺腺癌病人的独立预后因素。然后通过体外实验，在肺腺癌细胞系PC9、 A549中，利用SiRNA沉默SNAP47，进行功能表型探究，发现沉默SNAP47的表达能够抑制肺腺癌细胞的增殖、迁移和侵袭能力，且细胞周期阻滞于G2期；在整体动物水平上，通过裸鼠皮下成瘤实验证实SNAP47的促癌作用。对A549细胞株沉默SNAP47后进行RNA测序（RNA-seq），并对测序结果进行通路分析发现敲低SNAP47可能抑制了EGFR/ PI3K/Akt通路，表明SNAP47极有可能通过激活EGFR/ PI3K/Akt通路活性来增强肿瘤细胞侵袭转移进而促进肺癌恶性进展。