Trichoplax adhaerens: A Novel Model Organism in Cancer Research

Trichoplax adhaerens (Placozoa) is the simplest multicellular animal to be described. This organism lacks nervous tissue, muscle tissue and organs, and is composed of only five cell types organized into three layers. Placozoa are gaining popularity as a model organism due to their simple make-up and completely sequenced genome. The complete sequencing of this organism’s genome has revealed the presence of important genes in cancer such as TP53 and MDM2 genes. Along with the presence of these genes, there are also additional pathways commonly deregulated in cancer that are well conserved in this organism. T. adhaerens are able to survive exposure to 160Gy and even 240Gy of X-ray radiation. Though small dark bodies form within the main body, they tend to extrude those masses, and continue to reproduce afterwards. After exposure to both grades of radiation, there was a greater increase in the apparent population size of the treated population than the control population. There was also a greater decrease in surface area of the organisms exposed to 160Gy than the control organisms. This increase in population and decrease in surface area of the treated organisms could be due to the extruded bodies. We hypothesize that the observed extrusion is a novel cancer defense mechanism for ridding the animal of damaged or mutated cells. This hypothesis should be tested through longitudinal observation and genetic analysis of the extruded bodies.