Nuclear Interaction between ADR-Induced p65 and p53 Mediates Cardiac Injury in iNOS (−/−) Mice

Marsha P Cole,Daret K St Clair,Jitbanjong Tangpong,Terry D Oberley,Luksana Chaiswing,Kinsley K Kiningham

doi:10.1371/journal.pone.0089251

Abstract

Adriamycin (ADR) treatment causes an imbalance in the levels of nitric oxide (•NO) and superoxide (O2 •−) production leading to cardiac injury. Previously we demonstrated that mice lacking inducible nitric oxide synthase (iNOS) have increased oxidative stress and mitochondrial injury. The molecular events leading to increased mitochondrial injury in iNOS deficient mice is unknown. ADR in the absence of iNOS preferentially activates a proapoptotic pathway without a concurrent increase in prosurvival pathways. Treatment with ADR leads to an increase in DNA binding activity of nuclear factor kappa B (NFκB) and p53 in wildtype mice. Following ADR treatment, p53, but not NFκB DNA binding activity, as well as the level of Bax, a p53 target gene, was increased in iNOS (−/−) mice. This apoptotic signaling effect in iNOS (−/−) is alleviated by overexpression of manganese superoxide dismutase (MnSOD). Increases in NFκB and p53 in ADR-treated wildtype mice did not lead to increases in target genes such as MnSOD, bcl-xL, or Bax. Moreover, co-immunoprecipitation analysis revealed that p65, a prominent member of the NFκB family, interacts with p53 in the nucleus. These results suggest that NFκB and p53 may counter act one another's actions in ADR-treated wildtype (WT) mice. Further, these results identify a novel mechanism by which oxidative stress may regulate transcription of proapoptotic genes.

Highlights

Adriamycin (ADR) remains one of the most widely used chemotherapeutic agents, there is a known dosedependent cardiac toxicity
Manganese superoxide dismutase activity and protein expression is increased in TgM (+/+) and inducible nitric oxide synthase (iNOS) (2/2) -TgM (+/+) mice
Adriamycin is a broad spectrum anthracycline antibiotic used for treatment of most solid tumors; its clinical usefulness is limited by the potential lethal cardiac injury

Summary

Introduction

Adriamycin (ADR) remains one of the most widely used chemotherapeutic agents, there is a known dosedependent cardiac toxicity. Redox cycling of ADR occurs through both enzymatic and non-enzymatic reactions Enzymes such as cytochrome P-450 reductase, NADH dehydrogenase, xanthine oxidase, as well as non-enzymatic reduction catalyzed by iron, have been shown to participate in the redox cycling of ADR and the formation of O2N2 [1]. We have demonstrated that overexpression of manganese superoxide dismutase (MnSOD) is protective against ADR-induced cardiac injury using a transgenic mouse model [2,3,4]. This result suggests that O2N2 production as a result of ADR treatment most likely occurs in the mitochondria. Inducers of MnSOD protein and activity such as phenylbutyrate, a histone deacetylase inhibitor, are cardioprotective in ADR-induced toxicity [5]

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