Abstract
CIGB-300 is a clinical-grade anti- Protein Kinase CK2 peptide, binding both its substrate’s phospho-acceptor site and the CK2α catalytic subunit. The cyclic p15 inhibitory domain of CIGB-300 was initially selected in a phage display library screen for its ability to bind the CK2 phospho-acceptor domain of HPV-16 E7. However, the actual role of this targeting in CIGB-300’s antitumoral mechanism remains unexplored. Here, we investigated the physical interaction of CIGB-300 with HPV-E7 and its impact on CK2-mediated phosphorylation. Hence, we studied the relevance of targeting E7 phosphorylation for the cytotoxic effect induced by CIGB-300. Finally, co-immunoprecipitation experiments followed by western blot were performed to study the impact of the peptide on the E7-pRB interaction. Interestingly, we found a clear binding of CIGB-300 to the N terminal region of E7 proteins from HPV-16 type. Accordingly, the in vivo physical interaction of the peptide with HPV-16 E7 reduces the CK2-mediated phosphorylation of E7, as well as its binding to the tumour suppressor pRB. However, the targeting of E7 phosphorylation by CIGB-300 seemed to be dispensable for the induction of cell death in HPV-18 cervical cancer-derived C4-1 cells. These findings unveil novel molecular clues to the means by which the CIGB-300 triggers cell death in cervical cancer cells.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
A.C.R. ailyn.ramon{at}cigb.edu.cu
O.M. basukala{at}icgeb.org, P.M. paola.massimi{at}icgeb.org, M.T. miranda.thomas{at}icgeb.org.
Y.P. ypererapereranegrin{at}ccbjic.com