Regulatory loci sae is required for S.aureus-induced apoptosis in carcinoma cell line

WILL, I. F.; RASPANTI, C. G.; PRUCCA, C.; RIVAROLA, V.; BOGNI, C. I.; NAGEL, R.

Rosario. Argentina.

Congreso; XLII Reunión Anual Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2006

Staphylococcus aureus has the ability to invade and persist within eukaryotic cells. It possesses several cell surface adhesion molecules that allows its binding to non-professional phagocytes. The internalized bacteria are able to induce apoptosis. Global regulatory loci agr and sigB have been shown to play a role in the induction of apoptosis by S. aureus in epithelial and endothelial cells lines. Global regulatory locus saeRS consists of a two-component regulatory system that upregulates the synthesis of several exoproteins at the transcriptional level. The aim of the present study was to investigate the role of the sae locus on the ability of S. aureus to induce apoptosis in the human breast cancer cell line MCF-7.The prococols for these experiments were mainly based on the methods described by Bayles et al. (Infect. Immun. 1998, 66: 336). The results revealed that six hours after internalization of S. aureus strain RN6390 (wild type) MCF-7 cells displayed morphological changes compatible with apoptosis. In contrast, the isogenic sae mutant RC200, which internalized at levels similar to those of RN6390, failed to induce apoptosis. DNAladdering experiments confirmed the lack of apoptosis by the sae mutant. These observations suggest that alpha-hemolysin, as well as other as yet unidentified virulence determinants, might trigger the apoptotic events induced by S. aureus.