The Function Of MTOR In Helicobacter Pylori CagA Induced Cell Physiological Change

Gastric cancer is the fifth leading cause of cancer in the world,every year 700,000 new deaths occur due to this deadly disease,and over 60%of gastric cancer are due to infection with Helicobacter pylori.The pathogenicity of Helicobacter pylori come from multiple sources,CagA,among them is one that is yet to be completely understood.CagA is secreted from Helicobacter pylori through type IV secretion system into the host cell and hijacks the host’s normal signal pathways,and in this process affects metabolism,cellular structure and in the end,causing carcinogenesis.In previous studies,we found that whether by direct infection with CagA+ strains of Helicobacter pylori or by over-expressing CagA in gastric cancer cells,causes a cell morphological change termed "hummingbird phenotype",named for the extremely elongated shape of the cells afflicted.Through drug screening,we find the durg called rapamycin,which is a potent mTOR signal pathway inhibitor,can block the cell’s morphological change.This study uses a tet-off inducing CagA over-expression system within the human gastric cancer cell line AGS(here by termed A10 cell line),utilizing techniques such as gene knockdown,western blotting,Real-Time PCR,microscope observation and cell counting to explore the connection between mTOR signal pathway and CagA induced cellular changes.Through experiment we find that NF-kB signal pathway does not block hummingbird phenotype,only mTOR inhibitor rapamycin can effective block that process.Through invasion assay we also find that rapamycin can decrease A10 cells invasive abilities and EMT process.By knockdown experiments we distinguished two mTOR complexes mTORcl and mTORc2 and identified mTORcl as the pathway that blocks CagA induced events.Finally through western blotting we identified the affected upstream and downstream targets within the mTOR singal pathway.Exploring the role of mTOR in the CagA signal cascade helps us uncover the pathogenicity of Helicobacter pylori,and provides new methods in the targeted treatment of gastric cancer and other types of cancer,due to the wide variety of cancer with mTOR involvemen.