Interactions between SIRT1 and AP-1 reveal a mechanistic insight into the growth promoting properties of alumina (Al2O3) nanoparticles in mouse skin epithelial cells

Swatee Dey, Vasudevan Bakthavatchalu, Michael T. Tseng, Peng Wu, Rebecca L. Florence, Eric A. Grulke, Robert A. Yokel, Sanjit Kumar Dhar, Hsin Sheng Yang, Yumin Chen, Daret K. St Clair

Research output: Contribution to journalArticlepeer-review

78 Scopus citations

Abstract

The physicochemical properties of nanomaterials differ from those of the bulk material of the same composition. However, little is known about the underlying effects of these particles in carcinogenesis. The purpose of this study was to determine the mechanisms involved in the carcinogenic properties of nanoparticles using aluminum oxide (Al2O3/alumina) nanoparticles as the prototype. Well-established mouse epithelial JB6 cells, sensitive to neoplastic transformation, were used as the experimental model. We demonstrate that alumina was internalized and maintained its physicochemical composition inside the cells. Alumina increased cell proliferation (53%), proliferating cell nuclear antigen (PCNA) levels, cell viability and growth in soft agar. The level of manganese superoxide dismutase, a key mitochondrial antioxidant enzyme, was elevated, suggesting a redox signaling event. In addition, the levels of reactive oxygen species and the activities of the redox sensitive transcription factor activator protein-1 (AP-1) and a longevity-related protein, sirtuin 1 (SIRT1), were increased. SIRT1 knockdown reduces DNA synthesis, cell viability, PCNA levels, AP-1 transcriptional activity and protein levels of its targets, JunD, c-Jun and BcL-xl, more than controls do. Immunoprecipitation studies revealed that SIRT1 interacts with the AP-1 components c-Jun and JunD but not with c-Fos. The results identify SIRT1 as an AP-1 modulator and suggest a novel mechanism by which alumina nanoparticles may function as a potential carcinogen.

Original languageEnglish
Pages (from-to)1920-1929
Number of pages10
JournalCarcinogenesis
Volume29
Issue number10
DOIs
StatePublished - 2008

ASJC Scopus subject areas

  • Cancer Research

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