Antitumor Function And Mechanism Study Of EBV-inhibiting Polypeptide

Epstein-Barr virus(EBV)is a kind of human gammaherpesvirus,which is well known for contributing to oncogenesis.EBV latent infection is associated with a various type of cancers,such as Burkitt's lymphoma,Hodgkin's disease,nasopharyngeal carcinoma and gastric cancer.Virus persistence is closely relative to virus infected cancer cell survival.One of the most important latent viral proteins,Epstein-Barr Virus Nuclear Antigen 1(EBNA1)is expressed in all kinds of latent infection.During latent infection,EBNA1 binds to Origin of Plasmid Replication(OriP)to activate virus replication and viral protein transcription.Pyrrole-Imidazole Polyamide(PIP)is a kind of synthetic minor-groove binder which binds to designated DNA sequences with high affinity and selectivity.PIPs can modulate gene expression by competitively displace transcriptional factors or other proteins from DNA.In this thesis,a PIP-Hoechst 33258 conjugate called EIP-2 was designed and synthesized to target OriP region and block EBNA1-OriP binding,in order to inhibit virus replication and EBV-positive cell proliferation.The results demonstrated that EIP-2 bound to OriP and block EBNA1 binding both in vitro and in vivo with high selectivity and affinity.EIP-2 selectively inhibited EBV-positive cell proliferation,while have insignificant effect on EBVnegative cells.EIP-2 eradicated EBV episomes by significantly inhibiting virus replications in cells,and virus protein expression was also reduced.Most notably,EIP-2 inhibited EBV-positive tumor growth by interrupting virus replication in mice xenograft tumor model with low toxicity.This thesis demonstrated the molecular mechanism of inhibiting EBV-positive tumor by PIP,which was proved efficiently against EBV replication and EBV-positive tumor growth.EIP-2,the PIP-Hoechst conjugated molecule developed in this thesis would be a highly potential candidate for further drug development.