LATS1转导对胃癌细胞内Hippo-YAP信号通路的分子调控机理

Gastric cancer is one of the most common gastrointestinal malignancies worldwide, and is the second most common cause of death from cancer. Tumor invasion and metastasis are the main reasons leading to the death of patients with gastric cancer. So, exploring the molecular mechanisms and therapeutic targets of gastric cancer with metastasis is one of the key issues which need to be resolved. Recently, it has been reported that large tumor suppressor 1 (LATS1) is involved in development and progression of some tumors via regulation of the Hippo-YAP signaling pathway. Our previous studies have also shown that ectopic expression of Hippo-YAP pathway is closely associated with tumorigenesis of gastric cancer, and decreased expression of LATS1 in gastric cancer with lymph node metatasis is negatively related to increased expression of Yes-associated protein (YAP), the effector of Hippo-YAP pathway. In this study, we explore the following issues: ① Effect and regulatory mechanism of LATS1 transduction on gastric cancer cell proliferation, apoptosis, metastasis and Hippo-YAP pathway; ② Establishment of orthotopic implantation gastric cancer metastasis model in severe combined immunodeficiency (SCID) mice, and molecular mechanism of LATS1 transduction on gastric cancer lymph node, liver metastasis and Hippo-YAP pathway; ③ Molecular mechanism of Hippo-YAP pathway on gastric cancer cell invasin and metastasis in vitro and in vivo. Taken together, these studies will help elucidate the effect and molecular mechanism of LATS1 transduction on gastric cancer cell invasin and metastasis, and provide the experimental and theoretical basis for prevention of gastric cancer metastasis and improvement of patients with gastric cancer.

胃癌是国内外最常见的消化道恶性肿瘤之一，肿瘤侵袭与转移是导致胃癌患者死亡的主要原因，研究胃癌转移的调控机制及治疗靶点是当前需要解决的关键问题之一。近期有作者报道 LATS1通过调控Hippo-YAP通路参与肿瘤发生与进展。我们研究亦表明，Hippo-YAP通路异常表达与胃癌发生发展密切相关， LATS1在有淋巴结转移的胃癌组织中表达降低，与YAP表达呈负相关。故本项目拟探讨以下问题：① LATS1转导对胃癌细胞增殖、凋亡、转移及Hippo-YAP信号通路的调控作用机制；② 建立重度联合免疫缺陷（SCID）小鼠原位移植胃癌转移模型，探讨LATS1对胃癌淋巴结、肝转移以及Hippo-YAP通路的作用机制；③ Hippo-YAP通路在体内外对胃癌浸润与转移的分子作用机理。以上有助于阐明LATS1在胃癌侵袭与转移中的作用及其调控机制，为预防胃癌转移及改善胃癌患者的预后提供有力的实验及理论依据。

本课题项目阐明了Hippo信号通路效应蛋白YAP在胃癌组织的高表达，以及沉默YAP在体内外抑制胃癌细胞增殖，克隆形成及侵袭转移，诱导细胞凋亡和周期阻滞，其作用机制与下调FGF-1、CTGF、MMP-2/-9、CyclinD1、BCL-2，上调Caspase-3/-9、TIMP-1/-2、E-Cadherin表达有关。证实了Hippo-YAP信号通路轴心蛋白LATS1在胃癌组织低表达，与胃癌转移呈负相关，LATS1低表达与胃癌患者不良生存有关，是胃癌患者生存和复发的独立预后因素。进而，过表达LATS1抑制胃癌细胞增殖和侵袭潜能，诱导细胞凋亡和周期阻滞；而沉默LATS1促进胃癌细胞增殖和侵袭，减少细胞凋亡和促进细胞周期进程，其作用机制与下调YAP及其下游MMP-2/-9、CyclinD1、BCL-2表达，上调Bax表达，抑制YAP核聚集有关。进而，通过构建SCID小鼠胃癌肝转移模型，确认LATS1过表达抑制胃癌生长和肝转移，IHC显示LATS1下调YAP、CTGF、MMP-2/-9、BCL-2，上调Bax表达。通过阐明LATS1转导对Hippo-YAP信号通路调控及其在胃癌发生发展中的作用机制，为胃癌诊疗提供潜在生物学靶标。受该课题资助目前发表SCI论文13篇，国内统计源期刊5篇。培养硕士研究生2名（张瑞、陆雯雯），博士研究生2名（张靖、王歌）。人才培养方面，课题组张靖博士，2013年7月荣获上海市优秀毕业生，2015年9月入选国家博士后管理委员会与香港学者协会联合颁发“香江学者奖”，至香港中文大学攻读博士后，2016年12月被特聘为上海市中西医结合学会消化专业委员会委员兼秘书。该课题顺利结题，使课题组人员的科研水平和实力提高了一个新的台阶。