Hallmarks of Cancer
Sustaining Proliferative Signaling
The first Hallmark of Cancer is the cell’s ability to sustain proliferative signaling. In other words, the cell divides and multiplies uncontrollably. Normally, healthy cells have control over factors that affect the growth of a cell. Healthy cells can control how often they divide, how the cells are going to be structured, and what functions the cells will have. A cell’s ability to multiply without a controlled signal is a key characteristic of a cancer cell.
A ligand, such as a growth factor, binds to a receptor located on the cellular membrane. This connection results in some sort of response, such as cellular proliferation.
This can happen in several ways. First, the production of growth factors that promote cell division may increase. These growth factors may be generated in neighboring cells and relayed to the cancer cell to increase proliferation. Second, the number of receptors on the surface of the cell may also increase. Receptors are responsible for receiving the signal of the growth factor. The growth factor and receptor work hand-in-hand, just like a basketball and a hoop. If the growth factor is the basketball and the receptor is the hoop, increasing the number of basketballs increases the chance to score. Increasing the number of hoops also increases the chance to score. An increase in the number of receptors may stimulate a cell to proliferate even with a low amount of growth factors. The structure of these receptors may also be altered in order to promote proliferation of the cancer cells.