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When two normally occurring hormones are brew together, the effects on women could turn dangerous, scientists have discovered.
When the hormones insulin and estrogen interact, the result is the growth and proliferation of breast cancer cells. Women with diabetes are more likely to get breast cancer, and women with breast cancer are more likely to get diabetes.
What Dr. Victoria Knutson found in her initial lab experiments is that "when breast cancer cells are bathed in estrogen, as occurs in pre-menopausal women, the cells are more sensitive to insulin, which stimulates growth."
Knutson is associate professor in the Department of Integrative Biology and Pharmacology at The University of Texas Medical School at Houston.
"We now know that there is interaction between estrogen and insulin signaling," she says. From her research, the insulin is not causing breast cancer, but it encourages growth in already existing cancer cells.
In the lab, Knutson says, breast cancer cells treated with insulin alone have no impact on the growth of the cells. When breast cancer cells are treated with estrogen, it induces growth. "However, if we add both together, there is a synergy, and we have amplified growth. That amplification increases with higher concentrations of insulin. More insulin is worse," she says and adds, "the impact then for a diabetic woman is horrible."
In a woman who does not have diabetes, the insulin level rises each time she eats and within two hours goes back down. If there is a snack, it shoots up and down quickly. But, with the diabetic, that insulin level goes up and stays there.
If the woman is pre-menopausal, estrogen is also present. Consequently, estrogen in the presence of steadily elevated insulin has an impact on breast cancer growth.
In the 1970s Knutson says, there were studies that demonstrated that diabetic women had a two-to three-fold higher risk for getting breast cancer. "Finding one factor with such a risk is significant."
Breast cancer growth is a complicated puzzle. Knutson is studying one of the pieces, a molecule called LAR, which deactivates the insulin receptor.
LAR has been implicated in diabetes because it helps to turn off the insulin signal. "Although we don't know why, LAR also has been linked to breast cancer that has metastasized or spread to distant sites in the body," she explains.
"We were looking at breast cancer in diabetics, and there was LAR again. It is important because breast cancer cells treated with estrogen decreased the expression of the LAR molecule. This means that the insulin receptor is super active and helps promote the growth of the cancer, even in the absence of insulin. So just by treating the cells with estrogen, we turned on the insulin pathway."
One big question Knutson has is LAR's function in metastasis—the spread of cancer to other parts of the body. Knutson plans to work with the UT M. D. Anderson Cancer Center to study tissue taken from women with breast cancer, both pre-metastatic and metastatic (both localized and spreading breast cancer) tissue.
"There are tests to identify a person in a pre-diabetic state. We already know that a woman with gestational (while pregnant) diabetes is at risk for developing the disease when she is older. Both African-Americans and Hispanics have a predisposition for diabetes," Knutson says. "Except for family history, there is no good predictor for breast cancer. So, if a woman has a family history of both diabetes and breast cancer, that should put her on notice."
By looking at the level and location of LAR she hopes to understand the role of the molecule and if it could be used as a predictor or risk factor for metastatic breast cancer, especially in women who are at risk for diabetes.
Knutson fervently believes that a diabetic woman should be vigilant about being tested for breast cancer or at least have the recommended mammograms for her particular age.
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Dr. Victoria Knutson is an associate professor in the Department of Integrative Biology and Pharmacology at the UT Medical School.
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Eating healthy
reverses metabolic syndrome
Dr. Tasnime Akbaraly of University College London and her colleagues were interested if healthy eating could actually turn-the-tide and reverse metabolic syndrome, which is having 3 or more of the following risk factors: excess abdominal fat; high triglycerides, hypertension, low levels of HDL the “good” cholesterol, or type 2 diabetes. Having metabolic syndrome doubles a persons’ risk of heart disease and greatly increases the odds of developing type 2 diabetes.
The researchers studied 339 British civil servants with metabolic syndrome, and how closely the adhered to the Alternative Healthy Eating Index (AHEI) to see if it could help reverse metabolic syndrome. The AHEI is a set of published nutritional guidelines by the Harvard School of Public Health in 2002 that emphasizes whole grains, fruits, vegetables and decreased red meat consumption.
Five years into the study, nearly 50% no longer had metabolic syndrome. People who followed the AHEI guidelines the closest were nearly twice as likely to have reversed their metabolic syndrome. The results of the study were published in Diabetes Care, online July 29, 2010.
Dr. Alice Lichtenstein, an expert on diet and heart health from Tufts University in Boston who was not involved in the study said, "It's not about focusing on individual components of the diet, it's really the whole package, and that becomes important because it means that if one of the components of a healthy diet is to eat more fruits and vegetables, just buying a pill saying that there's a concentrated extract of fruits and vegetables is probably not what's going to help you."
Call and make an appointment with Wellness Coach Sam Hester, CWC, CPT, LWMC, at 713-500-3327. It's confidential and free. For more information on the wellness services provided, visit UT Counseling and WorkLife Services.
