| ||
| Vol. 20, No. 10 |
| June 1, 1998 |
|
Diabetes, Breast Cancer: A Connection? by NORA K. SHIRE The University of Texas-Houston Medical School By doing simple tests in the laboratory, Dr. Victoria P. Knutson is proving, for the first time, a 30-year-old medical theory: an interaction between the hormones insulin and estrogen results in the growth and proliferation of breast cancer cells. "What I am finding is that the estrogenic influence on breast cancer cells appears to modulate the response of those cells to insulin, and when the cells are bathed in estrogen, as occurs in premenopausal women, the breast cancer cells are more sensitive to insulin, which stimulates growth," she explains.  Dr. Victoria Knutson This all began last fall when Dr. Knutson, an associate professor in The University of Texas-Houston Medical School's department of integrative biology, pharmacology and physiology, was reading the clinical reports from a breast cancer research project and learned that women with diabetes were excluded from the studies. (Her interest in breast cancer research began more than a decade ago because of an ongoing project funded by the U.S. Army.) Her interest was piqued because for the 14 years she has been a UT-Houston faculty, her research focus has been Type II diabetes, which usually occurs after the age of 40, and insulin, which is a growth factor. What was unusual to Dr. Knutson is that although this estrogen-insulin interaction was a conclusion of epidemiologists as far back as the 1970s, her literature search showed that no one had gone into the laboratory to find support or proof. So she did "very simple molecular experiments using very simple biology" to address the question: Does estrogen affect the activity level of the insulin receptor? "Not only are the estrogens affecting the insulin receptor level, they are also affecting the insulin receptor signaling properties," she observes. From her research, the insulin is not causing breast cancer but is encouraging growth in already existing cancer cells. Dr. Knutson presented her findings as an abstract at the Experimental Biology '98 conference recently in San Francisco. What do her findings mean? "In therapy, the use of thamoxfen, a drug that blocks estrogen, might be useful in diabetic women because it would block the estrogen's ability to turn on the insulin receptors," explains Dr. Knutson. Clinically, she 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. Dr. Knutson wants to do a major research project looking for the key to this basic mechanism of what the estrogens are doing that has this effect on the insulin. "As a basic scientist I want to know what the estrogens are doing to the insulin sensory system," she comments. "In fact, maybe this effect is not unique to breast cancer; perhaps, it is important to normal reproductive growth, like the ovaries or the endometrial tissue. It might even maintain a normal growth program for tissues." Only time and work at the laboratory bench will tell.
©2006 Texas Medical Center E-Mail: tmc-info@tmc.edu URL: http://www.tmc.edu/tmcnews/06_01_98/page_03.html |