Upregulation of DNA repair genes and cell extrusion underpin the remarkable radiation resistance of Trichoplax adhaerens

PLoS Biol. 2021 Nov 17;19(11):e3001471. doi: 10.1371/journal.pbio.3001471. eCollection 2021 Nov.


Trichoplax adhaerens is the simplest multicellular animal with tissue differentiation and somatic cell turnover. Like all other multicellular organisms, it should be vulnerable to cancer, yet there have been no reports of cancer in T. adhaerens or any other placozoan. We investigated the cancer resistance of T. adhaerens, discovering that they are able to tolerate high levels of radiation damage (218.6 Gy). To investigate how T. adhaerens survive levels of radiation that are lethal to other animals, we examined gene expression after the X-ray exposure, finding overexpression of genes involved in DNA repair and apoptosis including the MDM2 gene. We also discovered that T. adhaerens extrudes clusters of inviable cells after X-ray exposure. T. adhaerens is a valuable model organism for studying the molecular, genetic, and tissue-level mechanisms underlying cancer suppression.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • DNA Damage / genetics
  • DNA Damage / radiation effects
  • DNA Repair / genetics*
  • DNA Repair / radiation effects
  • Gene Expression Regulation / radiation effects
  • Placozoa / anatomy & histology
  • Placozoa / genetics*
  • Placozoa / radiation effects
  • Radiation Exposure
  • Radiation Tolerance / genetics*
  • Sequence Analysis, DNA
  • Up-Regulation / genetics*
  • Up-Regulation / radiation effects
  • Whole Genome Sequencing
  • X-Rays