Until researched by Enrique Martín Blanco, at the Institute of Biology of Barcelona (Spain), it was somehow felt that cancers metastasize (spread) because of some inherent characteristic of cancer cells. Now it has been shown that the ability to metastasize is common to most cells – a normal capacity – that happens to be useful for cancer. After all, what metastasize really means is the ability of cells to leave one location, travel through the bloodstream or lymph system, and invade other tissue. It’s kind of a transport mechanism, and as the research discovered is used as a normal function during periods of growth and for healing.
It’s been known for a while that metastization in cancer cells is induced by proteins, specifically BMPs (from ‘bone morphogenetic proteins’) or TGFß (from ‘transforming growth factor-ß’). These proteins not only trigger the migration of cells, but also provide them with a kind of ‘pass code’ that gives them invasive capabilities.
Working with the biologists best bug, the fruit fly (Drosophila melanogaster), the researchers found a similar protein (Decapentaplegic protein or Dpp) that triggers cell migration. Cells with Dpp in them are both mobile and invasive – just as it is with BMPs and TGFß.
Martin-Blanco said, “If we block the signal of Dpp in the cells, they stop moving. However, if the Dpp protein is over expressed, cells have even more and enhanced migratory and invasive capacities.
The authors have worked with embryos of the fly Drosophila melanogaster, during the formation of its abdominal epithelium, in metamorphosis. This is a process where histoblasts (embryonic cells) that will form the fly abdomen replace larval epidermal cells. The histoblasts remain at the beginning in small nests or groups of cells, and they progressively multiply, spreading and invading the space to substitute all larval epithelial cells.
Seeing the Dpp protein work as part of the normal process of fruit fly growth, was the first time that ‘metastasis’ could be identified with a normal function of cells. It’s hoped that further research will identify more relationships between the action of normal cells and cancer cells. It’s hoped that eventually means will be found to regulate the protein action that triggers metastasis.