The Effect Of NOTCH1-regulated Expression Of Cancer Stem Cell Markers On Proliferation And Invasiveness Of Ovarian Cancer Cells

Part one The expression of NANOG and CD44 in epithelial ovarian cancer tissues and its clinical significance Objective: To investigate the expression and clinical significance of cancer stem cell markers NANOG and CD44 in epithelial ovarian cancer(EOC)tissues.Methods: The expression of NANOG and CD44 in EOC and benign ovarian tumor tissues was detected by immunohistochemical method.Results: The positive expression rates of NANOG and CD44 in EOC were significantly higher than that in benign ovarian tumor tissues(P< 0.001);In EOC,positive correlation was observed between the expression levels of NANOG and CD44(r=0.346,P<0.01).The positive expression rate of NANOG was associated with clinical stage and histological grade(P<0.05),and has no relationship with age,pathological types,lymphatic metastasis and the location of tumors;The positive expression rate of CD44 was associated with clinical stage and lymphatic metastasis(P<0.05),and has no relationship with age,histological grade,pathological types and the location of tumors.Conclusions: NANOG and CD44 take part in the occurrence and development of EOC;both of them have a relationship with bad prognosis.NANOG combined with CD44 can be used as indicators of tumor staging and prognosis.Part two The role of NOTCH1 in regulating the expression of cancer stem cell markers and capacities of proliferation and invasion of ovarian cancer cells Objective: To investigate the role of NOTCH1 in regulating the expression of ovarian cancer stem cell markers and capacities of proliferation,invasion and tumorigenesis of epithelial ovarian cancer cells SKOV3 and A2780.Methods: Using lenti-virus transfection combined with RNA interference technique to knockdown NOTCH1.The expression of NOTCH1 and other cancer stem cell markers in SKOV3 and A2780 was detected by Western blot,and their corresponding mRNA levels were detected by RT-qPCR.The changes in the invasiveness and the sensitivity to cisplatin caused by NOTCH1 knockdown were determined by scratch-wound healing assay,Transwell assay and CCK-8 assay.In vivo tumorigenicity and proliferation ability were tested in nude mice.Results: The expression of NANOG,OCT-4,CD44 and CD 117 proteins was inhibited after NOTCH1 knockdown in both SKOV3 and A2780 cell lines(P<0.05).The levels of NANOG,OCT-4,CD44 and CD117 mRNA decreased after NOTCH1 knockdown in SKOV3(P<0.05);only NANOG and OCT-4 mRNA decreased in A2780(P<0.05).NOTCH1 knockdown also inhibits the proliferation and invasiveness but increases the sensitivity to cisplatin of SKOV3 and A2780 cell lines(P<0.05).The proliferation of ovarian cancer cells SKOV3 in tumor xenografts was inhibited as a result of NOTCH1knockdown(P<0.05)?Conclusions: NOTCH1 takes part in regulating the expression of genes pertaining to cancer stem cells;targeted down-regulation of NOTCH1 inhibits proliferation and invasiveness of ovarian cancer cells.NOTCH 1 is a promising new target to control the malignant progress of EOC.