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Cancer cells can reactivate a cellular process that is an essential part of embryonic development. This allows them to leave the primary tumor, penetrate the surrounding tissue and form metastases in peripheral organs.
During an embryo’s development, epithelial cells can break away from the cell cluster, modify their cell type-specific properties, and migrate into other regions to form the desired structures. This process is known as an epithelial–mesenchymal transition EMT is reversible and can also proceed in the direction from mesenchymal cells to epithelial cells (MET).
It is repeated multiple times during embryonic development and ultimately paves the way for the formation of organs in the human body. Tumor cells can reactivate the program. Although this is a completely normal process during embryogenesis, it also plays an important role in the spread of tumor cells within the body and in the formation of metastases.
Tumor cells are able to reactivate the EMT/MET program. By doing so, they obtain characteristics of stem cells and develop strong resistance to classical and state-of-the-art targeted cancer therapies. An EMT also makes it easier for cancer cells to break away from the primary tumor, to penetrate into surrounding tissue and into blood vessels, to spread throughout the body and to form metastases in distant organs, which is ultimately responsible for the death of most cancer patients.
Regulation the cellular EMT program prevents the development of malignant tumors and the formation of metastases such as in the case of breast cancer, researchers focused specifically on microRNAs (miRNAs), a class of very short non-coding RNAs with a considerable effect on gene regulation.
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