Tuesday, December 11, 2012 (Last Updated: 12/12/2012)TUESDAY, Dec. 11 (HealthDay News) -- Excess nutrients associated with menopausal weight gain are deposited into the breast tumors of rats who were already obese before menopause, but the tumors can regress after treatment with an insulin sensitizer, according to a study published online Dec. 7 in Cancer Research.
Erin D. Giles, Ph.D., from the University of Colorado Anschutz Medical Campus in Aurora, and colleagues compared nutrient distribution in lean and obese female rats with breast tumors before and after surgical ovariectomy (inducing menopause and weight gain).
The researchers found that excess nutrients were deposited into mammary and peripheral tissues in the lean animals, but into the tumors of obese animals. Tumors from obese animals had increased progesterone receptor expression, which was associated with the expression of glycolytic and lipogenic enzymes, glucose uptake, and markers of proliferation. When treated with metformin, the tumors regressed and progesterone receptor expression decreased. Breast tumors from postmenopausal women showed a similar correlation between progesterone receptor expression and metabolic upregulation.
"The window of menopausal weight gain may provide a narrowed window during which insulin sensitizers and other interventions that improve metabolic control could be highly efficacious for the treatment and prevention of postmenopausal breast cancer," Giles and colleagues conclude.
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