Androgen Receptors Amplify Breast Tumor Progression in Obese Rats

New findings show tumor growth in obese rats is driven by especially sensitive androgen receptors.
The androgen receptor has context-dependent roles in the growth and progression of breast cancer. Although high tumor androgen receptor levels predict favorable patient outcomes, several studies have indicated these receptors promote tumor growth––particularly in ER-positive breast cancers after endocrine therapy.
In a study published in Hormones & Cancer, investigators sought to examine the potential role of androgen receptors in obesity-associated mammary tumors, post endocrine therapy.
“Our original goal was to make a model of obesity and breast cancer that would reflect the condition in women,” said first author Elizabeth Wellberg, PhD. “At first, we were disappointed to discover that rats don’t make much estrogen in fat tissue like humans do. But we then realized that this aspect of the model gave us an excellent opportunity to study cancer progression after anti-estrogen treatment.
“Because fat cells in these rats don’t make estrogen, they are like human breast cancer patients treated to remove estrogen. This allowed us to ask what is responsible for obesity-associated tumor progression in conditions of low estrogen availability.”
In the animal models of obesity and breast cancer, investigators found the tumor cells had especially sensitive androgen receptors in obese animals, but not lean animals. This allowed the cells to magnify growth signals from the hormone testosterone.
The obese rats were treated with the anti-androgen drug enzalutamide. The findings showed the drug shrank existing tumors and new tumors did not develop. The question still remains, however, as to what is creating these overactive androgen receptors.
“When you talk about what’s different between lean and obese individuals there are a lot of things––resistance to insulin, high sugar, and an elevated inflammatory response, what we call…

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