A Study On The Mechanism Of MARVELD1 In Regulating DNA Damage Response And Colorectal Cancer Therapy Resistance

Genome instability is a hallmark of cancer that leads to an increase in genetic alterations,thus enabling the acquisition of additional capabilities required for tumorigenesis and progression.Various types of DNA damage are important sources of genomic instability;the repair mechanisms and the molecules that regulate these mechanisms collectively referred to as the DNA Damage Response(DDR)system.PARP1(Poly(ADP-Ribose)Polymerase 1)mediates multiple signal transduction in the DDR as a master regulator.When DNA damage occurring,PARP1,as a sensor of DNA damage,binds to the damage site and initiates auto-PARylation.Subsequently,PARP1 recruits the related proteins to the damage sites to facilitate the repair.PARP inhibitors have been clinically applied to the treatment of multiple tumors with remarkable efficacy.Therefore,uncovering the regulatory factors of PARP1 contributes to a more comprehensive view of tumorigenesis and treatment strategies.MARVELD1(MARVEL Domain Containing 1)is a functional gene obtained in our laboratory.Its expression was down-regulated in multiple malignancies of epithelial origin due to hypermethylation in the promoter region,but the levels were elevated in tumors such as pancreatic cancer and glioma;our previous study illustrated that MARVELD1 exhibits significantly responsive changes in tumor cells after exposure to stimuli,however,its function and mechanism are unclear.In this study,we investigated that MARVELD1 interacting with PARP1 mediates DDR,maintains genomic stability and influences the DNA damage therapy efficacy.In this work,phenotypic experiments were performed to confirm that MARVELD1 significantly down-regulates DNA damage levels and promotes DDR;the association between MARVELD1 expression and overall survival in the TCGA(The Cancer Genome Atlas)database was analyzed and high MARVELD1 expression was found to be associated with poor prognosis;experiments using MARVELD1 knockout mice demonstrated that MARVELD1 deletion resulted in spontaneous genomic instability and increased sensitivity to DNA damage It was demonstrated that MARVELD1 contributes to the maintenance of genomic stability by regulating DDR both in vitro and in vivo,at the cellular and tissue levels,respectively.In order to investigate how MARVELD1 is involved in the regulation of the DDR system,this study identified the interactors of MARVELD1 and obtained multiple pathways related to the DDR by functional enrichment;validating PARP1 as a key interactor of MARVELD1;PARP1 facilitated the nuclear translocation of MARVELD1 under DNA damage conditions by the PARylation.Our data verified that MARVELD1 regulates DDR from the perspective of its interactors and elucidated the mechanism of MARVELD1 responsive nuclear translocation.Based on the above results,this paper further explored the molecular biological significance of the interaction between MARVELD1 and PARP1.It was confirmed that MARVELD1 could recruit NAA50(N-Alpha-Acetyltransferase 50)to facilitate PARP1 acetylation and prevent its ubiquitinated degradation,thus promoting the maintenance of PARP1 protein stability.The significance of the interaction between MARVELD1 and PARP1 was revealed from another perspective,and the “regulation loop” was formed with MARVELD1 nuclear translocation dependent on PARP1.To analyze the causes of poor prognosis associated with high MARVELD1 expression,the prognostic features of MARVELD1 were validated using colorectal cancer tissue microarrays;analyzing the relationship between endogenous MARVELD1 levels and chemotherapy sensitivity in CRC cell lines and confirming the regulatory relationship between MARVELD1,PARP1 and NAA50;patient-derived xenografts were used to clarify the association of MARVELD1 expression levels with treatment.The prognostic features of MARVELD1 were characterized from different aspects,showing that MARVELD1 is involved in the regulation of DDR and contributes to the maintenance of genomic stability through interacting with PARP1,leading to DNA damage therapy resistance and poor prognosis.In conclusion,this study reveals that MARVELD1 depends on PARylation for nuclear translocation and promotes PARP1 protein stability by enhancing NAA50-mediated acetylation,thus forming a "feedback loop" to regulate the DDR system;the partnership of MARVELD1 and PARP1 confers therapeutic resistance and provides new insights for CRC patients applicable to chemotherapy combined with PARP inhibitors.