Novel tools to analyze the function of Salmonella effectors show that SvpB ectopic expression induces cell cycle arrest in tumor cells

PLoS One. 2013 Oct 21;8(10):e78458. doi: 10.1371/journal.pone.0078458. eCollection 2013.

Abstract

In order to further characterize its role in pathogenesis and to establish whether its overproduction can lead to eukaryotic tumor cell death, Salmonella strains able to express its virulence factor SpvB (an ADP-ribosyl transferase enzyme) in a salicylate-inducible way have been constructed and analyzed in different eukaryotic tumor cell lines. To do so, the bacterial strains bearing the expression system have been constructed in a ∆purD background, which allows control of bacterial proliferation inside the eukaryotic cell. In the absence of bacterial proliferation, salicylate-induced SpvB production resulted in activation of caspases 3 and 7 and apoptotic cell death. The results clearly indicated that controlled SpvB production leads to F-actin depolimerization and either G1/S or G2/M phase arrest in all cell lines tested, thus shedding light on the function of SpvB in Salmonella pathogenesis. In the first place, the combined control of protein production by salicylate regulated vectors and bacterial growth by adenine concentration offers the possibility to study the role of Salmonella effectors during eukaryotic cells infection. In the second place, the salicylate-controlled expression of SpvB by the bacterium provides a way to evaluate the potential of other homologous or heterologous proteins as antitumor agents, and, eventually to construct novel potential tools for cancer therapy, given that Salmonella preferentially proliferates in tumors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP Ribose Transferases / genetics*
  • Actins / genetics
  • Apoptosis / genetics*
  • Caspase 3 / genetics
  • Cell Line, Tumor
  • G2 Phase Cell Cycle Checkpoints / genetics*
  • HCT116 Cells
  • HeLa Cells
  • Humans
  • Salmonella / genetics*
  • Virulence / genetics
  • Virulence Factors / genetics

Substances

  • Actins
  • Virulence Factors
  • ADP Ribose Transferases
  • Caspase 3

Grants and funding

This work was supported by the grant “Proyecto de Excelencia P07-CVI02518” from the Andalusian government and by a fellowship from the Andalusian government to BMP. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.