PI3K and Cell Growth

The regulation of cell growth, i.e., cell size, is another key feature of tumori-genesis that is under the control of the PI3-K pathway. Central to the control of cell growth is the mammalian target of rapamycin (mTOR), which activates p70S6 kinase and inhibits elongation-initiation factor 4E binding protein (4E-BP1), culminating in the stimulation of protein synthesis (71). Recently, the pathway linking PI3-K to p70S6 kinase has been further defined at the biochemical and genetic level following the elucidation of the function of two proteins, hamartin and tuberin, which are mutated in the genetic disorder tuberous sclerosis (72). These proteins form a complex, and tuberin acts as a GTPase-activating protein that inhibits the activity of the small GTPase, Rheb. Phosphorylation of tuberin by PKB inhibits GTPase activity. In its GTP-bound state, Rheb activates mTOR via an undefined mechanism (73). Bearing in mind that mTOR is upstream of p70S6kinase, rapamycin has emerged as a potential treatment for both tuberous sclerosis and cancer. An ester analog of rapamycin, CCI-779, inhibits growth of PTEN-deficient human myeloma cell lines (74) and reverses growth of PTEN-deficient prostate cancer cell xenografts (75).

Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

Get My Free Ebook

Post a comment