The Roles And Mechanism Of CNDP2, Versican In Human Gastric Cancer

Gastric cancer has a higher rate of incidence, metastasis and mortality. To furtherexplore the related oncogenes or tumor suppressor gene, and to explore the related areas ofmetastasis of gastric cancer, is of great significance for the prevention, diagnosis andtreatment of this cancer. The expression changes of certain oncogenes or tumor suppressorgene is closely related to the gastric carcinogenesis. While the sustaining damage of genesor genomic, which caused by the epigenetic change, would change the microenvironmentof cell growth and then contribute to the tumor invasion and migration. Thus, the presentstudy aims to investigate tumor suppressor gene and tumor metastasis-associatedmolecules profiling during different phases of molecular mechanisms of gastriccarcinogenesis and metastasis.Chapter Ⅰ: CNDP2is Downregulated in Gastric Cancer and Suppresses GastricCancer Growth by Activating the MAPK Signaling PathwayCytosolic non-specific dipeptidase2(CNDP2) is ubiquitously expressed in all humantissues. Increasing evidence suggests that the dipeptidase appears to do more than justperform an enzymatic activity, it is functionally important in cancers as well. However, theexpression and molecular function of CNDP2in gastric cancer remain largely unknown.In our study, Tissue microarray blocks containing primary gastric cancer and adjacentnormal mucosa specimens obtained from182patients were constructed. Expression ofCNDP2in these specimens was analyzed using immunohistochemistry, RT-PCR, Q-RT-PCR and Western blotting. Analysis implications between the expression of CNDP2and clinical pathological characters were investigated. And then, the plasmid GV142mediated upregulation of CNDP2and lentiviral-mediated knockdown of CNDP2werebuild to transfect gastric cancer cell line AGS and SGC-7901, respectively. Aftertransfection, the cell proliferation, apotosis and cell cycle were analysized by cell viabilityassay (CCK-8), colony formation assay and flow cytometry. Here, we show that theexpression of CNDP2is commonly downregulated in gastric cancer tissues relative to thematched adjacent non-tumour tissues. The expression of CNDP2changed according to thedegree of differentiation of gastric cancer epithelial cell lines. Functionally, the ectopic expression of CNDP2resulted in the significant inhibition of cell proliferation, inductionof cell apoptosis and cell cycle arrest, and ROS generation. The ectopic expression ofCNDP2suppressed gastric tumour growth in nude mice. In addition, lentiviral-mediatedknockdown of CNDP2significantly increased cell proliferation and tumorigenesis in axenograft model. We further revealed that the reintroduction of CNDP2transcriptionallyupregulated p38and activated JNK, while the loss of CNDP2increased thephosphorylation of ERK, but not p38or JNK. Thus, these results suggest that CNDP2actsas a functional tumour suppressor in gastric cancer via activation of the MAPK signallingpathway.Chapter Ⅱ: Interleukin-11promotes the progress of gastric carcinoma viaabnormally expressed VersicanVersican, a ubiquitous component of the extracellular matrix (ECM), accumulates bothin tumor stroma and cancer cells and is highly regulated by various cytokines. The aberrantexpression of versican and its isoforms is known to modulate cell proliferation,differentiation, and migration, all of which are features of the invasion and metastasis ofcancer; versican is also known to favour the homeostasis of the ECM. Interleukin-11(IL-11) is an important cytokine that exhibits a wide variety of biological effects in gastriccancer development. Here, we analysed the expression of versican isoforms and found thatthe major isoforms expressed by both gastric carcinoma tissue and gastric cell lines wereV0and V1, and V1was significantly higher in gastric carcinoma tissue. The treatment ofthe gastric cell lines AGS and MKN45with rhIL-11resulted in a significant increase in theexpression of V0and V1. Exogenous IL-11increased migration in AGS and MKN45cells,whereas these effects were reversed when the expression of V0and V1were abolished bysiRNA targeting versican V0/V1. Collectively, these findings suggest that the abnormallyexpressed versican and its isoforms participate, at least in part, in the progress of gastriccarcinoma triggered by IL-11.