Phospho-ΔNp63 α /Rpn13-dependent regulation of LKB1 degradation modulates autophagy in cancer cells

Yiping Huang, Edward A. Ratovitski

Research output: Contribution to journalArticle

Abstract

Oxidativue stress was shown to promote the translocation of Ataxia-telangiectasia mutated (ATM) to cytoplasm and trigger the LKB1-AMPK-tuberin pathway leading to a down-regulation of mTOR and subsequently inducing the programmed cell death II (autophagy). Cisplatin was previously found to induce the ATM-dependent phosphorylation of ΔNp63α in squamous cell carcinoma (SCC) cells. In this study, phosphorylated (p)-ΔNp63α was shown to bind the ATM promoter, to increase the ATM promoter activity and to enhance the ATM cytoplasmic accumulation. P-ΔNp63α protein was further shown to interact with the Rpn13 protein leading to a proteasome-dependent degradation of p-ΔNp63α and thereby protecting LKB1 from the degradation. In SCC cells (with an altered ability to support the ATM-dependent ΔNp63α phosphorylation), the non-phosphorylated ΔNp63α protein failed to form protein complexes with the Rpn13 protein and thereby allowing the latter to bind and target LKB1 into a proteasome-dependent degradation pathway thereby modulating a cisplatin-induced autophagy. We thus suggest that SCC cells sensitive to cisplatin-induced cell death are likely to display a greater ratio of p-ΔNp63α/non-phosphorylated ΔNp63α than cells with the innate resistant/impaired response to a cisplatin-induced cell death. Our data also suggest that the choice made by Rpn13 between p-ΔNp63α or LKB1 to be targeted for degradation is critical for cell death decision made by cancer cells in response to chemotherapy.

Original languageEnglish (US)
Pages (from-to)959-968
Number of pages10
JournalAging
Volume2
Issue number12
Publication statusPublished - Dec 2010

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Keywords

  • Autophagy
  • Chemoresistance
  • LKb1
  • Oncogene
  • P63
  • Protein degradation
  • Tumor suppressor

ASJC Scopus subject areas

  • Aging
  • Cell Biology
  • Geriatrics and Gerontology

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