Diabetes-like symptoms from immune-suppressant drug explained
Scientists have discovered why diabetes-like symptoms develop in some patients prescribed rapamycin, an immune-suppressant drug widely used to prevent rejection in organ and bone marrow transplants.
Bacteria found on Easter Island
Rapamycin is a medication derived from bacteria in soil found on Rapa Nui, the Polynesian name for Easter Island. It blocks certain while blood cells that can reject foreign tissues and organs.
About 15 percent of patients develop insulin resistance and glucose intolerance when taking rapamycin, according to the study conducted by Dana-Farber Cancer Institute.
The study found that normal mice given rapamycin had more trouble regulating their blood sugar because of a drop in insulin signaling.
However, other mice lacking a protein called Yin Yang 1 (YY1) were protected against the diabetes-like effect of rapamycin.
Researchers hypothesized that YY1 was responsible for the diabetic effects. To test this, they bred mice that lacked the YY1 gene and protein in their skeletal muscles.
When these mice took rapamycin, they showed no change in their muscles' glucose uptake or insulin signaling and were immune to the diabetic effects of the drug.
One implication of these results is that physicians should consider prescribing diabetes medication along with rapamycin.
Researchers continue to study the effects of this medication on YY1, examining the possibility that dietary factors may play a role in the risk of developing diabetes symptoms.
Rapamycin being tested as cancer treatment
Rapamycin, is also known as sirolimus and sold under the brand name Rappamune. It's currently is being tested as a treatment for kidney cancer, brain tumors, mantle cell lymphoma, and other cancers.
The drug has also shown in recent animal studies to potentially extend life. A previous study published in Nature found that mice that took rapamycin lived longer than mice that did not.
The results of the current study raise concerns for over using the drug to treat cancers and slow aging.
Rapamycin inhibits the mTOR signaling pathway in cells, a factor regulating the growth and survival of cells. Elevated mTOR activity is one indicator of many cancers.
The study was published in Cell Metabolism.
Source: Dana-Farber Cancer Institute