Abstract 2476: Acetylated Survivin functions in DNA damage repair

Abstract

Abstract Survivin is an oncogenic protein that participates in cell division and inhibits apoptosis in cancer cells. These functions are dependent on its interaction with partner proteins within distinct subcellular compartments. Survivin is highly expressed in malignant tumors yet minimally expressed in normal tissues, making it an attractive target for molecular therapy. Inhibition of Survivin function enhances tumor cell sensitivity to radiation, the mechanism of which has been reported to result from a disruption of DNA-double-strand break repair processes. Recently, we demonstrated that Survivin is post-translationally modified by acetylation at numerous lysine residues, one of which is responsible for its subcellular transport. Acetylation at Lys-129 facilitates Survivin homodimerization which prevents its binding to the CRM1 nuclear export protein, inhibiting its translocation from the nucleus to the cytoplasm. The object of this study was to determine the potential relationship between Survivin acetylation and its function in nuclear repair processes. To elucidate the association between Survivin acetylation, nuclear localization and DNA double-strand break repair we subjected HeLa cells to 4Gy γXRT and examined Survivin acetylation at serial time points (20, 40, 60 min) after irradiation. An immediate deacetylation of Survivin was observed at 20 minutes, followed by an increase in both global acetylation and acetylation at Lys-129 at 40 minutes. The increase in Lys-129 acetylation correlated with its nuclear accumulation, as demonstrated by indirect immunofluorescence staining and immunoblotting after subcellular fractionation. Acetylated Survivin was found in endogenous immunoprecipitants with the DNA damage repair protein, Ku70, following γ-irradiation. Indirect immunoflourescence revealed co-localization of Ku70 and acetylated Survivin within the nucleus at similar time points after irradiation suggesting that Survivin acetylation may be required for Ku70 complex formation within the nucleus. These results implicate acetylated Survivin as a regulator of DNA damage repair through the Ku70 DNA repair pathway and further our understanding of Survivin function within the nuclear compartment of cancer cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2476. doi:10.1158/1538-7445.AM2011-2476