Signal Transduction Pathways in Breast Cancer: The Important Role of PI3K/Akt/mTOR

Figure 1

Overview of cell signalling mediated by the tyrosine kinase receptors (RTKs) Her2/Neu and estrogen receptors (ERs), two key components of breast cancer development. Their activation initiates the PI3K/Akt/mTOR and MAPK pathways, finally promoting cell growth, proliferation, survival, and other hallmarks of cancer. Although this is a review of PI3K/Akt/mTOR signalling, it is important to understand that the different pathways are connected by different points. In this figure, we have presented two examples: Ras, promoting PI3K activation, and how some AGC kinases (such as SGK-3) activated by mTORC2 also interact with the MAPK pathway. Additionally, GSK-3 plays an important role as well in the regulation of these pathways, represented in the figure. GSK-3 is an example of how complex those interactions are, by the inhibition and activation of different molecules implicated in PI3K and MAPK pathways.