New Study Describes Intracellular Pathway That Promotes Or Suppresses Breast Cancer
The cancerous behavior of the cells is dictated by intracellular signals that present the capacity to induce normal cells to act and become cancerous. The cancerous behavior of cells is defined by growing and reproducing out of control and increased survivability. Also this intracellular signals present the capacity to induce the death of cancerous cells or to make them stop growing. In breast cancer this intracellular signal is represented by TGF-beta which sometimes promote tumor growing and sometimes will suppress cancerous cells.
Researchers from the University of Colorado published in the journal Oncogene a study during witch they observed how breast cancers can switch the activity of TGF-beta pathway. This particular discovery is very important as it provides the know-how basis in the future to block TGF-beta intracellular pathway when it promotes tumor growing and to leave it untouched or even promote the intracellular pathway when it is suppressing cancerous cells.
Early in the human development, embryos need cells that are proliferating very quickly and this action is ensured by SIX1, a transcription factor that make cells to move from one area of the embryo to an other. When we reach adulthood, SIX1 intracellular pathway is switched off in almost all cells because as adults we don’t need that kind of higher proliferation rate. The scientists observed that many breast cancers reactivate SIX1 intracellular pathway that will in turn switch on the TGF-beta pathway from tumor suppressing mode to tumor promoting mode.
SIX 1 pathway can influence the activity of TGF-beta pathway through some small molecules called microRNAs, which present the capacity to regulate the activity of the genes that encode TGF-beta signals. Those microRNAs can attach to the genes that regulates the activity of TGF-beta and transform them in mutant genes that will inhibit the capacity of TGF-beta to stop cell growth. When this action occurs, TGF-beta is not only losing the capacity to stop cells from growing, but is also encouraging cells to start proliferate and to grow into new tissue.
High SIX1 or high microRNAs associated with SIX1 are a sign that a breast cancer is using TGF-beta signaling in a tumor-promoting way, leader of the study says.
All cases of breast cancers that present high levels of SIX1 or associate microRNAs represent the perfect candidates that can benefit from therapy with TGF-beta inhibitors, drugs that are turning off the signals of TGF-beta intracellular pathway and are currently in clinical trials. Researchers also pointed out that in patients where levels of SIX1 or microRNAs are normal, TGF-beta intracellular pathway is preffered to be left intact, because they think that the signals that are given by this pathway are helping the patients to fight against breast cancer.
In the future, scientists hope that they will be able to attack directly the SIX1 intracellular pathway. Due to the fact that this intracellular signaling mechanism is not present in most adult tissues researchers hope that they will be able to inhibit the development of breast cancer with very few side effects in the near future.