DNA损伤检查点蛋白调节子1通过抑制p53通路促进胆管癌细胞的增殖、迁移及侵袭OACSTPCD

Objective To investigate the effect of the mediator of DNA damage check point protein 1(MDC1)on proliferation,migration,invasion,cell cycle and cell apoptosis in cholangiocarcinoma(CCA)and the potential molecular mechanism.Methods The small interfering RNA(siRNA)specifically targeting MDC1 was used to transiently knock down MDC1.Recombined plasmid containing MDC1 was transiently transfected into RBE and Huh28 cells for over-expression of MDC1.Real time quantitative PCR(qPCR)and Western blotting were adopted to verify the effectiveness of MDC1 knockdown or overexpression.The proliferation of CCA cells was measured via CCK-8 and cell colony formation assays.Transwell and Invasion assays were used to detect cell migration and invasion while flow cytometry assays were employed to detect cell cycle and apoptosis.Gene set enrichment analysis(GSEA)was conducted to investigate the pathways which were significantly associated with MDC1,and the expression of p53 downstream protein was verified by Western blotting assay.Co-immunoprecipitation(Co-IP)assays were used to verify the interactions between MDC1 and p53.Flow cytometry and Western blotting assays were performed to find out whether MDC1 promoted cell cycle and cell apoptosis through p53 pathway.Based on The Cancer Genome Altas(TCGA)database,the difference in MDC1 expression levels between CCA and normal tissues was analyzed,and the correlations between the MDC1 expression levels and the clinical prognosis of CCA patients were investigated.Results Knockdown of MDC1 in RBE and Huh28 cells significantly inhibited cells proliferation,migration and invasion,significantly decreased the proportion of cells in S phase,and significantly increased the proportion of cells in G0/G1 phase and apoptosis rate while overexpression of MDC1 could significantly promote cell proliferation,migration and invasion,significantly increase the proportion of cells in S phase,and significantly decrease the proportion of cells in G0/G1 phase and apoptosis rate.It was found that MDC1 interacted with p53 in RBE and Huh28 cells,and MDC1 significantly down-regulated the expressions of p53,p-p53(Ser-15),BAX,PUMA and p21,but significantly up-regulated the expression of Bcl-2,which in turn promoted the tumorigenesis of CCA.MDC1 was up-regulated in CCA tissues compared to the normal tissues,and the high expressions of MDC1 were significantly associated with poor clinical outcomes of CCA patients.Conclusion MDC1 promotes the development of CCA by suppressing the p53 pathway,and MDC1 may be a candidate marker for the poor prognosis in CCA.