Title:A Reverse Structure-based Design of HPV E7 Inhibitor
Volume: 18
Issue: 4
Author(s): Wan Chein Tan, Shatrah Othman*, See Khai Lim, Nurshamimi Nor Rashid and Choon Han Heh
Affiliation:
- Department of Molecular Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
- Drug Design
and Development Research Group, University of Malaya, Kuala Lumpur, Malaysia
Keywords:
Human Papillomavirus E7, pRb, peptide inhibitor, LXCXE, cell cycle, in silico.
Abstract:
Background: Human papillomavirus (HPV) is a small, non-enveloped double-stranded circular
DNA virus. The high-risk types of HPV are claimed to be responsible for over 99% of cervical
cancers. One of the essential HPV oncoproteins, E7, is responsible for escaping from G1/S cell cycle
arrest in HPV-infected cells by binding to the retinoblastoma protein (pRb) through its LXCXE binding
site.
Objective: To design a peptide inhibitor targeting HPV E7 through an in silico approach.
Methods: In this study, the LXCXE binding domain of pRb is used as a target to design peptide inhibitors
using a reverse structure-based approach. The designed amino acid sequence from the B pocket of
pRb, named peptide Y, was further investigated in vitro analysis. The cytotoxicity of the peptide was
analysed in two cell lines, namely, CaSki, containing an integrated HPV16 genome, and HaCaT, an
immortalized keratinocyte cell. Cell cycle analysis was also carried out in both cell lines treated with
peptides.
Results: In the in silico approach, a 9-amino acids peptide sequence formed 4 conventional hydrogen
bonds with LXCXE motif was selected for in vitro assay. Based on the cytotoxicity analysis, the peptide
showed low toxicity in both cell lines, where the cell viability remained over 74% when treated
with peptide Y. The peptide also caused an accumulation of cells in G0/G1 (+5.4%) and S phase
(+10.2%) and a reduction of cells in the G2/M phase (-14.9%) in the CaSki cells with no significant effect
on normal cells, indicating it is a potential HPV inhibitor.
Conclusion: A peptide inhibitor, peptide Y, that was designed from the LXCXE binding motif in pRb
can inhibit HPV E7 by causing a cell accumulation effect in G0/G1, and S phases of the cell cycle in
the HPV transformed cell lines. These findings could contribute to HPV E7 peptide inhibitor in the future.
