Transcript: Prevent Cancer From Going on TOR
Over the last decade more than 5,000 papers have been published about TOR, an enzyme inhibited by the drug rapamycin, a drug used experimentally to extend lifespan, but already in use clinically to prevent the rejection of kidney transplants. Patients, who received rapamycin due to renal transplantation, had a peculiar “side effect,” a decrease in cancer incidence. In a set of 15 patients who had biopsy proven Kaposi’s sarcoma, a cancer that often affects the skin. Within three months after starting rapamycin therapy, all cutaneous Kaposi’s sarcoma lesions had disappeared in all patients.
This makes sense, given that TOR functions as a master regulator of cellular growth and proliferation. For example TOR is upregulated in nearly 100% of advanced human prostate cancers. Maybe that’s why dairy consumption has been found to be a major dietary risk factor. We used to think it was just all the hormones in milk, but maybe prostate cancer initiation and progression is also promoted by cow’s milk stimulation of TOR. Our understanding of mammalian milk has changed from a “simple food” to a species-specific endocrine signaling system, which activates TOR, promotes cell growth and proliferation and suppresses our body’s internal housecleaning mechanisms. Now normally, milk-mediated TOR stimulation is restricted only to infancy where we really need that constant signal to our cells to grow and divide.
From an evolutionary perspective it can be concluded that the persistent “abuse” of the growth-promoting signaling system of bovine milk by drinking milk over our entire life span maintains the most important hallmark of cancer biology, sustained proliferative signaling.
TOR appears to play a role in breast cancer too. Higher TOR expression has been noted in breast cancer tumors, and associated with more aggressive disease, and lower survival rate among breast cancer patients.
This could explain when women hospitalized for anorexia may end up with only half the risk of breast cancer. Severe caloric restriction in humans may confer protection from invasive breast cancer by suppressing TOR activation. But we don’t have to starve ourselves to suppress TOR, just reducing animal protein intake can attenuate overall TOR activity. Moreover, diets emphasizing plants, especially cruciferous vegetables, not only decrease TOR activation but they provide natural plant-derived inhibitors of TOR in broccoli, and green tea and soy, and turmeric, and grapes, along with other fruits and vegetables such as onions, strawberries, blueberries, mangoes and the skin of cucumbers.
Maybe that’s why plant-based diets are associated with lower risk for many cancers, the downregulation of TOR. Are we finally on the threshold of being able to fundamentally alter human aging and age-related disease? Only time will tell, but if the pace and direction of recent progress are any indication, the next 5,000 studies on TOR should prove very interesting indeed.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
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