TRPV4/Ca2+信号在血管活性肠肽（VIP）促胃癌侵袭转移中的作用机制研究

The mortality of gastric cancer (GC) increased year by year, and the invasion and metastasis have been the main cause of death. Therefore, it is of great importance to elucidate the molecule and mechanisms invovled in GC invasion and metastasis. The previous study demonstrated that vasoactive intestinal peptide (VIP), as an important regulatory factor in microenvironment, was upregulated in serum and tumor tissues of GC patients, and the high level of expression was positively correlated with invasion and metastasis of GC. However, the mechanisms of VIP in GC invasion and metastasis are still unknown. Calcium is an important second messanger, which has been proved to play an important role in promoting migration and invasion of cancer cells. Our preliminary experiments showed that VIP could increase the calcium influx in GC cells through the TRPV4 channel, and TRPV4 inhibitor could inhibit VIP-induced migration and invasion in GC cells. Thus, we hypothesize that VIP might activate TRPV4 channel to increase the calcium influx in GC cells and promote GC invasion and metastasis through TRPV4/Ca2+ signaling. This proposal will elucidate the molecular and functional mechanisms of VIP activating TRPV4 channel and regulating calcium signaling using molecular biology, calcium analysis and patch clamp. Moreover, we will further uncover the role of TRPV4/Ca2+ signaling in VIP-induced GC invasion and metastasis, which will provide the evidence for exploring the prevention target of GC metastasis.

胃癌致死率逐年上升,侵袭转移是其死亡的主要原因,阐明调控胃癌侵袭转移的分子及机制具有重要意义.既往研究表明,血管活性肠肽（VIP）作为微环境中的重要调节因子,在胃癌患者血清及癌组织中高水平表达并与胃癌侵袭转移密切相关,然而VIP调控胃癌侵袭转移的机制不清.Ca2+离子作为一重要的第二信使,已被证实在多种肿瘤细胞的迁移及侵袭转移中发挥重要调控作用.我们前期预实验发现VIP可通过TRPV4通道促胃癌细胞外Ca2+内流增加,而TRPV4抑制剂可抑制VIP促胃癌迁移及侵袭的作用.据此,我们推测“VIP可激活TRPV4通道开放促胃癌细胞外Ca2+内流增加,通过TRPV4/Ca2+信号参与胃癌侵袭转移的调控".本课题拟通过分子生物学、钙测定及膜片钳等技术,阐明VIP促TRPV4通道激活的分子及功能机制,并证实TRPV4/Ca2+信号在胃癌侵袭转移中的重要作用,为探寻胃癌侵袭转移的防治靶标提供依据.

胃癌在我国的致死率已跃居所有肿瘤第二位，虽然近年来胃癌的综合治疗取得了长足进展，但胃癌的早期侵袭转移使得胃癌的治疗及预后仍然较差，已成为胃癌患者死亡的主要原因。目前针对胃癌侵袭转移的分子机制并不十分清楚，研究阐明胃癌侵袭转移的分子及其机制对于胃癌的早期诊断和治疗具有重要的意义。既往研究表明,血管活性肠肽（VIP）作为微环境中的重要调节因子,在胃癌患者血清及癌组织中高水平表达并与胃癌侵袭转移密切相关，我们前期也发现，VIP可明显促进胃癌细胞迁移及侵袭。VIP及其受体VPAC1在胃癌组织中高表达，与胃癌侵袭转移及不良预后密切相关；血管活性肠肽可通过其特异受体VPAC1促进胃癌细胞体外侵袭及体内转移能力；VIP通过其受体VPAC1介导细胞内钙信号的增加而促进胃癌侵袭转移；VPAC1通过PLC-DAG信号激活TRPV4通道促进细胞外钙的内流；VIP/VPAC1通过TRPV4介导的钙依赖信号促进胃癌细胞的侵袭转移；VPAC1/TRPV4/Ca2+信号可进一步促进胃癌细胞VIP的表达及分泌，进而形成一条正向反馈通路加速和促进胃癌的侵袭转移。通过以上研究及结果，我们阐明了VIP通过调控胃癌细胞钙信号促进胃癌侵袭转移的机制，并证实TRPV4/Ca2+信号在胃癌侵袭转移中的重要作用，为探寻胃癌侵袭转移的防治靶标提供依据。