Mechanism of cellular uptake, intracellular transportation and degradation of the proapoptotic peptide CIGB-300 in low- and high-sensitive tumor cell lines.

HERNÁN G. FARINA; FERNANDO BENAVENT ACERO; SILVIO E. PEREA; YASSER PERERA; DANIEL F. ALONSO ; DANIEL E. GOMEZ

Lublin

Conferencia; 7 th Internationl Conference on Protein Kinase CK2 ?Protein kinase CK2, from basic insights to application; 2013

The John Paul II Catholic University of Lublin, Poland

CIGB-300 is a cyclic synthetic peptide that induces apoptosis in malignant cells, elicits antitumor activity in cancer animal models and shows tumor reduction signs when assayed in first-in-man Phase I trial in patients with cervical malignancies. The CIGB-300 peptide impairs phosphorylation by Casein Kinase 2 by targeting the substrate´s phosphoaceptor domain; moreover CIGB-300 can be delivered into cells by the cell penetrating peptide Tat. Previously, we demonstrated that CIGB-300 showed a differential antiproliferative effect in different tumor cell lines. In this work, it was studied the internalization of CIGB-300 in different populations of tumor. It was found that cell membrane heparan sulfate proteoglycans act as receptors for extracellular CIGB-300 uptake. The most sensitive cell lines showed higher intracellular incorporation of CIGB-300 peptide, in comparison to less sensitive cell lines. Furthermore CIGB-300 uptake is time- and concentration-dependent in all studied cell lines. It was shown that CIGB-300 has the ability to penetrate cells mainly by membrane direct translocation. However, a minor proportion of the peptide uses an energy-dependent endocytic pathway mechanism to gain access into the cells. CIGB-300 is internalized and transported into cells preferentially by caveolae-mediated endocytosis. Lysosomes are involved in CIGB-300 degradation; high sensitive cell lines showed degradation at earlier times compared to low sensitive cells. Altogether, our data suggests a mechanism of internalization, vesicular transportation and degradation pathway for CIGB-300 peptide in tumor cells.