Question

. Name a general condition that, when present, the immune system promotes the formation of tumors: ___________________________________.

Answer 1

The answer is related to the natural killer (NK) cells. These cells are in charge of killing cells that are infected by virus or tumorous cells. But there is a crucial regulator for this tumor cells killing activity: STAT5. This molecule is normally present in cells to upregulate transcription of certain factor for cell growth and cycle, but the NK cell only recieves the correct signal for killing the tumor cells when STAT5 is present. If STAT5 is not present (inhibited or eliminated) the NK cells not only doesn't kill the tumor cells, but it also helps them by promoting angiogenesis. Angiogenesis is the process in which blood vessels are created, and this greatly favors tumor cells, as they are constantly growing and dividing, thus they require a lot of resources.

The general condition is: Absence/inhibition of STAT5