The Effect Of Silencing Dipeptidyl Peptidase â…£/CD26on Invasiveness And Proliferation Of SKOV3Epithelial Ovarian Cancer Cells

Background and Objective：Ovarian cancer has the first death rate in all female reproductive systemmalignant tumors and its incidence has been rising in recent years. Epithelial ovariancancer has the highest incidence in all ovarian malignant tumors,many cases werediagnosed at late stage with different levels of transfer and cytoreductive surgery cannot cure these tumors completely.Its recurrence can not be avoided even though avariety of adjuvant therapy is done after successful surgery,so far the prognosis andtreatment of it is much far from the expectations of people.Sustaining proliferativesignaling stimulation,enabling replicative immortality,activating proliferation、invasion and metastasis are basic reasons of the malignant behavior during themultistep development of tumors.So exploring the molecular mechanism of ovariancancer in occurrence and development and searching new biological target for thetreatment of it is a focused issue for many obstetricians and gynaecologists.Tumor metastasis is a pathological process that the tumor cells after breakingaway from primary lesion tissue move to the other organ and tissue through the bloodvessels or lymph-vessel.The key step of the process is the degradation of tumors’ extracellular matrix.The collagen is the dominating ingredient of extracellularmatrix,and the gelatinases can degrade the collagen and it has high activity in tumortissue.So the study about the effect of the protein which has the activity of gelatinasesin the tumors’ invasion and metastasis becomes a focused issue for the researchers.Serine protease (serine-integral membrance peptidase，SIMP) family which hasthe role of degrading serine protein has a distinctive serine residual in the activecenter(the name’ birth), and degrades the extracellular matrix by activating serineresidual.There is a study that metastasis of the malignant tumor cells is closely relatedto the destruction of the matrix and SIMP may participate in malignant activity oftumors.Dipeptidyl peptidase Ⅳ (DPPⅣ) is one member of SIMP family,and it isalso called CD26by the reason of its expression on the surface of activated Tlymphocyte.It has dipeptidyl peptidase and the gelatin enzyme activity, which candegrade the extracellular matrix.In different cell types and individual organisms,CD26participates in regulating biological molecular activity, the protein hydrolysis,tissue repair,tumor cell migration,inflammation, invasion of tumor and otherphysiological and pathological process through hydrolysis, degradation of precursorsubstances and biological macromolecules, performing a variety of physiologicalfunctions.Studies have shown that CD26is related with cell malignant transformationand evolution process of tumors.Hiroto has reported that DPPⅣ promotesmetastasis and proliferation of malignant mesothelioma,Showing that DPPⅣ playsan active role in malignant behaviors of tumors.Recently at home and abroad,there are not much study about the role of DPPⅣ in proliferation and invasion of malignant tumors,not to mention the study inovarian cancer.It is unclear that what a role that DPPⅣ play in proliferation andinvasion of ovarian cancer.Our group preliminarily have found that the expression of DPPⅣ in the ovariancancer tissue and SKOV3cells is higher than the normal tissue,and the proliferation,and invasive ability of DPPⅣ/CD26+epithelial ovarian cancer is evidently strongerthan the DPPⅣ/CD26-cells. It shows that DPPⅣ can promote proliferation andinvasion of tumors.In this experiment,we silence DPPⅣ to explore its function ininvasion and proliferation of epithelial ovarian cancer,and to further know the role of occurrence and development of ovarian cancer to provide theoretical foundation forexploring the tumor’s progress and metastasis,and to provide new target for thebiological treatment of ovarian cancer.Materials and Experimental Methods：1.SKOV3was transfected with short hairpin RNA （shRNA） of DPPⅣ、GAPDH and empty plasmid(shCD26、shGAPDH、shNC)，respectively. Transfectionefficiency of the short hairpin RNA was estimated according to the amount of greenfluorescence by fluorescence microscope.2.The expression of DPPⅣ mRNA and protein of different plasms in SKOV3cells were examined by reverse transcription PCR and western blot,respectively.3.The Invasiveness, cell cycle and cell proliferation of different plasms inSKOV3cells were analysed using Matrigel invasion assay, flow cytometry and CellCounting Kit-8(CCK-8), respectively.Results：1.The transfection efficiency of shCD26,shGAPHD and shNC were59%,64%and60%(P>0.05),and the difference were not of with statistical significance.2.The expression level of DPPIV mRNA of shNC,shCD26,shGAPDH andnon-transfected was0.80±0.01，1.20±0.11,2.15±0.15and1.32±0.04.The level ofDPPIV mRNA of the shCD26-transfected was significantly lower than the otherthree groups(P<0.05)，so was the DPPIV protein of the shCD26-transfected.3.The cell number of transmembrane of shCD26,shNC and non-transfected wasrespectively37±4.08,65±4.74and66.8±3.82.The cell number of transmembraneand the cell activity of the shCD26were considerably below the shNC and thenon-transfected (P<0.05）. The shCD26-transfected cells demonstrated higher G0/G1propertion,,but contained S-phase cells and G2/M-phase cells at lowerlevels,.Compared to the shNC and the non-transfected,the difference was significant(P<0.05）. Conclusions：DPPⅣ may be involved in cell invasiveness and proliferation of SKOV3cells,to provide theoretical foundation for exploring the tumor’s progress andmetastasis,and to provide new target for the biological treatment of ovarian cancer.