| Objective: Dipeptidyl peptidase Ⅲ(DPP3),a zinc-dependent metallopeptidase,is upregulated in a variety of malignancies.However,little is known about its roles in the pathogenesis of these malignancies.The present study was designed to investigate the roles of DPP3 in the pathogenesis and progression of esophageal squamous cell cancer(ESCC).Methods: The expression level of DPP3 in ESCC tissues and adjacent normal tissues was detected in 93 cases of tissue biopsies collected from patients diagnosed with esophageal carcinoma by immunohistochemistry.The relationship between DPP3 expression and clinical pathological parameters of patients was analyzed.The correlation between DPP3 expression and prognosis of patients with esophageal cancer was analyzed based on follow-up data.Lentivirus interference was used to knock down the expression of DPP3 in Eca-109 and Te-1 esophageal squamous cancer cells,respectively.RT-q PCR and Western blotting were used to verify the transfection efficiency.The cells were divided into knockdown group(sh DPP3)and control group(sh Ctrl).The effect of DPP3 expression on cell proliferation,migration or apoptosis was determined in sh DPP3 and sh Ctrl followed by detection at the cellular level using a Celigo cell count assay,flow cytometry,wound-healing assay and Transwell assay as well as chip screening with a Human Apoptosis Antibody Array kit,which enables the quantitative detection of 43apoptosis-related proteins.Bioinformatics were used to further predict downstream signaling pathways and Western blotting were used to verify the effects of DPP3 knockdown on protein expression of proteins related to downstream signaling pathways.Finally,the above cells were implanted subcutaneously into Balb/c nude mice to construct a nude mouse tumor model,and the effect of DPP3 on tumor formation and proliferation of esophageal carcinoma cells in nude mice was verified in vivo.Results:(1)DPP3expression is localized in cytoplasm and nucleus.Statistical analysis confirmed a significantly higher DPP3 expression level in tumour tissues than in normal control tissues.The expression of DPP3 was significantly and positively correlated with lymph node metastasis(N stage).The overall survival rate of patients was related to clinical stage,N stage,lymph nodes metastasis and DPP3 expression,and high DPP3 expression was significantly associated with poor prognosis.(2)DPP3depletion resulted in reduced cell proliferation and migration and enhanced cell cycle arrest and apoptosis of EC cells.In addition,DPP3 depletion was associated with the upregulation of the pro-apoptotic proteins SMAC and p53 and the downregulation of the anti-apoptotic proteins cl AP-2,IGFBP-2 and TRAILR-4.After DPP3 knockdown,the expressions of p-AKT,CDK6,Cyclin D1 and PIK3 CA proteins were down-regulated,but the change of AKT protein was not affected.(3)The results of nude mouse tumor transplantation showed that the total fluorescence expression of transplanted tumors in sh DPP3 group was low,and the tumor volume and weight of transplanted tumors were significantly decreased compared with the control group.The positive rate of Ki67 expression in transplanted tumor tissues in sh DPP3 group was significantly decreased.DPP3 knockdown affected the m RNA expression of PI3 K and m TOR in transplanted tumors.Conclusions: DPP3 may promote cell proliferation,migration and survival of EC cells in vitro and tumour growth and invasion of esophageal carcinoma in vivo,and thus may serve as a molecular target for tumour therapy.In addition,DPP3 is associated with the pro-apoptotic proteins SMAC and p53 as well as the anti-apoptotic proteins cl AP-2,IGFBP-2,and TRAILR-4.DPP3 may participate in the occurrence and development of tumors through the PI3K/AKT pathway. |
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