骨髓基质干细胞分化对胃癌EMT/MET的调控及其在胃癌发生发展过程中的作用

Bone marrow mesenchymal stem cells (MSCs) as a kind of adult stem cells involve in the occurrence and stroma composition of gastric cancer , but the exact mechanism is not known. We found two subtypes progenitors in the MSC: epithelial progenitors (MSCs-EP) and stromal myofibroblasts progenitors (MSCs-SMP), which separately can induce gastric cancer cell MET and EMT characteristic respectively and participate in the initiation and development of gastric cancer。 We found the differential expression of Gli1 between MSCs-EP and MSCs-SMP up to 16 times by chip assay. Hence, we hypothesize that the transformation status of MSCs subtypes influences the occurrence and development of gastric cancer by the conversion of EMT/MET status in gastric cancer, and it is regulated by the Hedgehog pathway. We will explore MSCs, MSCs-EP, MSCs-SMP alone or mixed in different proportions on the carcinogenesis, development and metastasis of gastric cancer and the impact on the conversion of EMT/MET status in gastric cancer in vitro and vivo model. Moreover, the mechanism of Gli1 on gastric cancer in MSCs differentiation and regulation of EMT/MET status in MSCs and stomach cancer were explored by the regulation of Gli1 expression in MSCs.To investigate the role of MSCs of subtype differentiation, biological functions, regulatory mechanisms will help us open up a new way to clarify the mechanism and treatment of gastric cancer.

骨髓基质干细胞（MSCs）作为成体干细胞参与胃癌的发生和间质的构成，但具体机制未明。我们发现MSC中存在两种祖细胞：上皮样（MSCs-EP）和间质样（MSCs-SMP），分别诱导胃癌表现MET和EMT的特性并参与胃癌的发生发展；通过芯片技术发现Gli1在两者中的差异表达达16倍。首次提出MSCs亚型的转化状态影响胃癌EMT/MET转化从而影响胃癌的发生发展，并受Hedgehog通路调控的观点。本课题在体外及体内探讨MSCs、MSCs-EP、MSCs-SMP单独或不同比例混合对胃癌发生、发展和转移以及对胃癌EMT/MET转化的影响；通过调控MSCs中Gli1基因的表达为切入点，探讨Gli1在MSCs分化及其对胃癌EMT/MET转化调控的影响，从而了解其在胃癌发生、发展和转移过程中的作用机制。研究MSCs转化特点、生物学功能和调控机制，为阐明胃癌发生机理和治疗开辟新途径

上皮间质转化（EMT）是肿瘤细胞获得侵袭和转移能力的重要过程，已被众多的研究证实。而肿瘤细胞发生EMT的诱导因素多种多样。本项目组基于前期研究和后续相关研究指出，TGF-beta1可诱导骨髓基质干细胞（MSCs）EMT标志物E-Cad表达降低，N-Cad、Vim和Snail等表达增高，而BMP-7干预起到相反效应。进一步研究发现TGF-beta1和BMP-7干预可引起MSCs细胞内源性SHH通路关键分子表达变化，且下调MSCs细胞GLI1可引起MSCs间质上皮转化（MET），而上调GLI1引起MSCs细胞EMT；通过MSCs与胃癌细胞共培养，发现MSCs细胞EMT诱发胃癌细胞EMT，并增强胃癌细胞侵袭和转移能力；而MSCs细胞MET不影响胃癌细胞EMT和侵袭转移能力。因此，我们提出骨髓基质干细胞（MSCs）可能通过诱发胃癌细胞EMT，促使胃癌细胞获得和增强侵袭转移；而SHH通路在MSCs细胞EMT/MET过程中扮演重要作用。此外，课题组通过检测胃癌组织中肿瘤干细胞标志物CD44、SHH通路关键分子SHH和GLI1蛋白表达，发现CD44、SHH和GLI1在胃癌组织中高表达与胃癌肿瘤进展密切相关；且其高表达预示患者预后差。本研究证实Sonic Hedgehog信号通路关键因子SHH在胃癌组织中表达上调，SHH表达与胃癌肿瘤进展密切相关，SHH高表达提示胃癌患者具有更短的五年生存率；胃癌细胞自分泌SHH可通过PLCγ1-ERK1/2信号通路促进胃癌细胞增殖。本项目拓展研究证实FOXL1和MLKL蛋白在胃癌组织中低表达，且其低表达提示胃癌患者预后差；阿帕替尼作为VEGFR2特异性靶向药物，可显著抑制VEGF-VEGFR2信号通路异常活化胃癌的肿瘤进展。本项目部分研究已以学术论文形式被SCI收录；在本项目经费支持下，项目负责人培养毕业博士研究生2人，在读硕士研究生1人。