Involvement of PKC delta (PKCd) in the resistance against doxorubicin analogues

MARÍA INÉS DÍAZ BESSONE; DAMIAN E. BERARDI; PAOLA B. CAMPODÓNICO; LAURA B. TODARO; LEONARD LOTHSTEIN; ELISA D. BAL DE KIER JOFFÉ; ALEJANDRO J. URTREGER

BREAST CANCER RESEARCH AND TREATMENT

SPRINGER

Lugar: Dordrecht; Año: 2011 vol. 126 p. 577 - 587

0167-6806

Doxorubicin is an anti-tumor antibiotic widely used in the management of cancer patients. Its main mechanism of action involves the generation of DNA damage and the inhibition of topoisomerase II, promoting apoptosis. AD 198 is a novel doxorubicin analogue devoid of DNA binding and topoisomerase II inhibitory capacities. It has been proposed that AD 198 induces apoptosis by activating protein kinase C delta (PKCd); a PKC isoform described as growth inhibitory in a large number of cell types. We have previously demonstrated that PKCd overexpression in NMuMG cells induced the opposite effect, promoting proliferation and cell survival. In this work we found that PKCd overexpression confers an enhanced cell death resistance against AD 198 cytotoxic effect and against AD 288, another doxorubicin analog that preserves its mechanism of action. These resistances involve PKCd-mediated activation of two well known survival pathways: Akt and NF-kB. While the resistance against AD 198 could be abrogated upon the inhibition of either Akt or NF-kB pathways, only NF-kB inhibition could revert the resistance to AD 288. Altogether, our results indicate that PKCd increases cell death resistance against different apoptosis inductors, independently of their mechanism of action, through a differential modulation of Akt and NF-kB pathways. Our work contributes to a better understanding of the mechanisms involved in PKCd-induced resistance and may greatly impact in the rationale design of isozyme-specific PKC-modulators as therapeutic agents.