Complex diseases such as endometriosis are usually caused by a variety of complementary factors. For example, the epithelial to mesenchymal transition (EMT)– a phenomenon where epithelial cells become migratory rather than connected to other cells–is thought to be a requirement for endometriosis, and so is proliferation of cells that make up endometriotic lesions. Although these two processes seem to be associated, a group of researchers from the Medical University of Vienna and University of Toronto recently discovered that EMT and proliferation can act independently to form endometriotic lesions by acting through different gene expression and protein expression patterns.
EMT can be triggered by a protein known as TWIST1. This protein causes cells to release their cell-to-cell contacts by inhibiting production of the protein CDH1. Two other similar proteins are SNAIL and SLUG, which can also induce EMT.
On the other side of the board, expression of the gene MYC has been associated with increased proliferation rates in cells. Some studies have also suggested that MYC is involved in endometriosis because samples of endometriotic lesions from endometriosis patients show expression of MYC.
To establish whether or not EMT and proliferation are a concurrent phenomenon in endometriosis, the researchers collected tissue samples and investigated overlapping expression of TWIST, CDH1, SNAIL, SLUG, and MYC. The results of the study were published in the journal Reproductive Biology and Endocrinology, in the article, “Enhanced Epithelial to Mesenchymal Transition (EMT) and Upregulated MYC in Ectopic Lesions Contribute Independently to Endometriosis.”
A total of 74 endometriosis samples and 47 normal samples were analyzed for gene expression. Endometrial samples were both eutopic and ectopic in nature, and these were collected in one surgical procedure per patient. When the researchers looked at relative amounts of gene expression, TWIST1, SNAIL, and SLUG were highly expressed in endometrial tissues, and CDH1 was highly repressed as a result of TWIST1 activity. MYC followed a similar pattern of overexpression, but MYC was not always present where there was TWIST1, nor was there always TWIST1 were there was MYC.
“We found exclusive expression of either TWIST1 or MYC in the same samples, indicating that EMT and proliferation contribute independently of each other to the formation of endometriotic lesions,” concluded the authors. In fact, the research team found a significant inverse relationship of MYC and TWIST1 in paired samples. This means that TWIST1 and MYC do not work together to enhance endometriotic lesion formation and that if researchers are to use these genes to help diagnose endometriosis, an inverse pattern of expression should be expected.