Question

Describe what is epithelial to mesenchymal transition (EMT). Is the process of EMT essential for metastatic spread? Please give evidences that support your answer.

Answer 1

Epithelial to mesenchymal transition (EMT) ; is the process where the epithelial cells transformed in to mesenchymal cells.Mesenchymal ells are not well oraganised. During development, mesenchymal cells gain the ability to migrate, differentiate and transform into any kind of cells.EMT is essential for the numerous development processes like the formation of mesoderm and neural tube formation. EMT is also reversible like Mesenchymal to epithelial transition (MET).

The epithelial cells form the epithelial tissue which cover the internal and external body of an organism. These cells are polarized and form cell to cell adhesion . One of the functions of epithelial tissues are they act a protective barrier to the underlying tissues and organs.The epithelial cells are connected to each other by tight junctions, gap junctions and adherens junction.

During EMT, the epithelial cells lose the polarity and their cell to cell adhesion and gin the ability to migrate and diffrentiate and develop into specific organs. There are 3 main types of EMT ;

• Type 1 EMT is associated with the development such as embro development and organ dvelopment.
• Type 2 EMT is associated with repair process like, tissue repair, wound healing and regeneration process of tissue.
• Type 3 EMT is associated with Tumor metastasis.

EMT has also been shown to occur in the initiation of cancer metastasis progression.EMT comprise the processes by which cells transit between epithelial and mesenchymal states, and they play integral roles in both normal development and cancer metastasis. More recently, the role of adherent EMT in pathogenesis of fibrosis and metastasis of certain carcinogenic tumors has been described . This has challenged the field to more clearly define EMT. It help researchers more accurately assess the relationship between the normal process of cell differentiation and the analogous pathological EMT processes. Such EMT processes occur in both epithelial and non-epithelial cancer. Not all cells will undergo EMT simultaneously, and not all cells that have undergone EMT will successfully metastasize. Cancer progenitor cell characteristics, environmental factors, extracellular and intracellular signaling, and epigenetic changes all influence whether a cell undergoes EMT and metastasis. There are two findings ;

In first one the cancer progenitor cells present in a tumor do not undergo EMT simultaneously, so the cancerous population contains cells at different stages of differentiation. These stages are not fixed. Cancer progenitor cells at any stage of differentiation can undergo EMT to achieve a further stage of differentiation and develop into an advanced grade of cancer. Essentially, these grades are different, they arise from the same progenitor cell and undergo differential EMT at different time points. The second hypothesis suggests that some cancer progenitor cells initially undergo EMT and then metastasize following clonal expansion. In this case, a metastatic tumor will share a signature with the cell that originally underwent EMT, and thus, every cancer grade should come from a different progenitor cell.