title: Potent anti-tumor effect generated by a novel human papillomavirus (HPV) antagonist peptide reactivating the pRb/E2F pathway.
abstract: Human papillomavirus type 16 (HPV16) E7 is a viral oncoprotein believed to play a major role in cervical cancer. In this study, an antagonist peptide against HPV16E7 protein was first identified from screening the c7c phage display peptide library. The binding specificity and affinity of the selected peptide to HPV16E7 were tested by competitive enzyme-linked immunosorbent assay (ELISA). The antagonist peptide showed obvious anti-tumor efficacy both in cell lines and animal tumor models. Significant cell proliferation inhibition with high specificity was noted when HPV16-positive cells were treated with the peptide. This anti-tumor efficacy was resulted from overriding the activities of HPV16E7 and reactivating the pRb/E2F pathway, as shown by a series of experiments. Flow cytometry analysis revealed that the selected peptide induced G1 arrest in a dose-dependent manner. Competitive ELISA, pull down, and Co-IP experiments indicated that the selected peptide disrupted the interaction between HPV16E7 and pRb proteins both in vitro and in vivo. Luciferase reporter assay verified that transcription activities of E2F were suppressed by the peptide through restoration of pRb. RT-PCR and Western blot revealed that it reduced cyclins A, D1, and E1 expression, and led to HPV16E7 protein degradation, but pRb protein stabilization. The current study suggests that this specific peptide may serve as a potential therapeutic agent for HPV16-positive cervical cancer.
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing, People's Republic of China.
authors.forename: Cai-ping
authors.initials: CP
authors.lastname: Guo
authors.forename: Ke-wei
authors.initials: KW
authors.lastname: Liu
authors.forename: Hai-bo
authors.initials: HB
authors.lastname: Luo
authors.forename: Hong-bo
authors.initials: HB
authors.lastname: Chen
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
authors.forename: Shen-nan
authors.initials: SN
authors.lastname: Sun
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.forename: Laiqiang
authors.initials: L
authors.lastname: Huang
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002999:Clone Cells; D050684:E2F Transcription Factors / Q000378:metabolism*; D004705:Endocytosis / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D051379:Mice; D027383:Papillomaviridae / Q000187:drug effects*; D050725:Papillomavirus E7 Proteins / Q000378:metabolism; D019151:Peptide Library; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D055550:Protein Stability / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D050684:E2F Transcription Factors; D050725:Papillomavirus E7 Proteins; D019151:Peptide Library; D010455:Peptides; D012333:RNA, Messenger; D016160:Retinoblastoma Protein