Mechanism Study Of UBD Facilitating P53 Degradation In Promoting The Proliferation Of Colorectal Cancer

PurposeUbiquitin D(UBD)is a member of the ubiquitin-like modifier(UBL)family and is highly expressed in a variety of cancers including colorectal cancer(CRC).However,the mechanisms of its regulatory roles in CRC are largely elusive.In this study,we explored the effect of UBD on the proliferation of CRC.Methods1.QRT-PCR and Western blotting were used to detect the differential expression of UBD in tumor tissues and adjacent non-tumor tissues of patients with colorectal cancer.The relationship between UBD expression level detected by immunohistochemical and clinicopathological data of these patients was statistically analyzed.2.The sh UBD knockdown plasmid and p CDH-UBD overexpression plasmid were constructed,the lentivirus were packed and CRC cells were infected with lentiviral to establish of stable cell lines.CCK-8,colony formation,Ed U and flow cytometry assays were used to detect the functional changes of CRC cells transfected with UBD stable expression plasmids in vitro.A xenograft model was constructed to assess the effect of UBD on the growth of CRC cells in vivo.3.The expression level of p53 in CRC cells with stable interference or overexpression of UBD was verified by Western blotting.Proteasome inhibition and cycloheximide chasing experiments were performed to explore the effect of UBD on p53 proteolysis.Results1.UBD was overexpressed in CRC tumor tissues compared with non-tumor tissues,and its overexpression is positively correlated with tumor size(p = 0.037)and TNM stage(p = 0.017)of CRC patients.2.Functionally,overexpression of UBD can promote the activity and proliferation of CRC cells in vitro,and promote tumorigenesis in vivo,while knockdown of UBD has the opposite effect.3.In terms of mechanism,UBD down-regulates the expression of p53 by accelerating the degradation of p53 and shortens its half-life,thereby further affecting the decrease of downstream target genes p21 and the increase of Cyclin D1,Cyclin E,CDK2,CDK4 and CDK6.In addition,in vivo experiments have shown that UBD-induced tumor growth in nude mice depends on the reduction of p53.ConclusionOur research proves that UBD could promote the proliferation of CRC cells and ultimately promote the development of CRC by mediating the degradation of p53 protein.