May 26, 2014
A Restricted Diet May Be A Good Way To Avoid Breast Cancer
Brett Smith for redOrbit.com - Your Universe Online
While decreasing calorie intake might be a great way to lose weight – it can also help in the fight against breast cancer. According to a new study in the journal Breast Cancer Research and Treatment, the highly-aggressive, triple negative subtype of breast cancer is less likely to spread throughout the bodies of lab mice if they are fed a restricted diet.
The study team found when they fed mice with this specific type of breast cancer 30 percent less than those provided with constant food, the cancer cells reduced their generation of microRNAs 17 and 20 (miR 17/20). Scientists have discovered that this class of miRs is frequently elevated in triple negative cancers that spread, or metastasize.
Breast cancer patients are usually treated with hormone therapy to hamper tumor expansion, and steroids to combat the side negative effects of chemotherapy. Both remedies can cause the patient to have a modified metabolism which can cause weight gain. Women often acquire an average of 10 pounds in their 1st year of therapy. Recent reports have revealed that too much weight can make common treatments for breast cancer less efficient, and those who put on pounds during treatment often have worse cancer outcomes, the researchers said.
"That's why it's important to look at metabolism when treating women with cancer," Simone said.
The new study built on previous research by the same team that had shown a lower calorie intake boosted the tumor-killing effects of radiation therapy. The researchers said their latest study was focused on determining which molecular pathways were involved in this effect.
They found that the microRNAs miR 17 and 20, RNA segments that control other genes in the cell, dropped the most when mice were given both radiation therapy and a lower-calorie diet. This decrease in turn heightened the generation of proteins which sustain the extracellular matrix.
"Calorie restriction promotes epigenetic changes in the breast tissue that keep the extracellular matrix strong," Simone explained. "A strong matrix creates a sort of cage around the tumor, making it more difficult for cancer cells to escape and spread to new sites in the body."
Determining a link to miR 17 also gives scientists a molecular target for detecting cancers that are more prone to spread and, possibly, for establishing a new drug to treat the cancers. Theoretically, a drug that cuts miR 17 could have the same effect on the extracellular matrix as a lower calorie diet, the researchers said.
However, focusing on a single molecular pathway is not likely to be as effective as calorie restriction, according to Simone. Triple negative breast cancers are usually quite distinct genetically from patient to patient. If a low calorie-diet works as well in women as it does in animal models, then it would probably alter the expression patterns of a sizable set of genes, hitting numerous targets at once without toxic adverse effects.