Tumor Suppressor WWOX Contributes to the Elimination of Tumorigenic Cells in Drosophila melanogaster

PLoS One. 2015 Aug 24;10(8):e0136356. doi: 10.1371/journal.pone.0136356. eCollection 2015.

Abstract

WWOX is a >1 Mb gene spanning FRA16D Common Chromosomal Fragile Site, a region of DNA instability in cancer. Consequently, altered WWOX levels have been observed in a wide variety of cancers. In vitro studies have identified a large number and variety of potential roles for WWOX. Although its normal role in vivo and functional contribution to cancer have not been fully defined, WWOX does have an integral role in metabolism and can suppress tumor growth. Using Drosophila melanogaster as an in vivo model system, we find that WWOX is a modulator of TNFα/Egr-mediated cell death. We found that altered levels of WWOX can modify phenotypes generated by low level ectopic expression of TNFα/Egr and this corresponds to altered levels of Caspase 3 activity. These results demonstrate an in vivo role for WWOX in promoting cell death. This form of cell death is accompanied by an increase in levels of reactive oxygen species, the regulation of which we have previously shown can also be modified by altered WWOX activity. We now hypothesise that, through regulation of reactive oxygen species, WWOX constitutes a link between alterations in cellular metabolism observed in cancer cells and their ability to evade normal cell death pathways. We have further shown that WWOX activity is required for the efficient removal of tumorigenic cells from a developing epithelial tissue. Together these results provide a molecular basis for the tumor suppressor functions of WWOX and the better prognosis observed in cancer patients with higher levels of WWOX activity. Understanding the conserved cellular pathways to which WWOX contributes provides novel possibilities for the development of therapeutic approaches to restore WWOX function in cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caspase 3 / genetics
  • Cell Death / genetics
  • Cell Transformation, Neoplastic / genetics*
  • Chromosome Fragile Sites / genetics
  • Disease Models, Animal
  • Drosophila Proteins / biosynthesis
  • Drosophila Proteins / genetics*
  • Drosophila melanogaster
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Neoplasms / genetics*
  • Neoplasms / pathology
  • Tumor Necrosis Factor-alpha / biosynthesis
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Suppressor Proteins / biosynthesis
  • Tumor Suppressor Proteins / genetics*
  • WW Domain-Containing Oxidoreductase

Substances

  • Drosophila Proteins
  • Tumor Necrosis Factor-alpha
  • Tumor Suppressor Proteins
  • WW Domain-Containing Oxidoreductase
  • WWOX protein, Drosophila
  • Caspase 3

Grants and funding

This work was supported by the National Health and Medical Research Council of Australia (519125 to LVO and RIR 207830 to LVO), the Cancer Council South Australia (to RIR), an Australian Research Council (ARC)-NHMRC Research Network Grant (RN0457079 to RIR) and an Australian Research Council Special Research Centre for the Molecular Genetics of Development (CMGD) Grant (S0001531 to RIR).