Soy Isoflavones Sensitize Lung Cancer Cells

DETROITSoy isoflavones have the ability to improve radiation outcomes in lung cancer patients by blocking cancer cells' DNA repair mechanisms while protecting normal tissue, according to a new study published in the April issue of the Journal of Thoracic Oncology.

"These natural soy isoflavones can sensitize cancer cells to the effects of radiotherapy, by inhibiting survival mechanisms which cancer cells activate to protect themselves," said Dr. Gilda Hillman, associate professor in the Department of Radiation Oncology at Wayne State University's School of Medicine and the Karmanos Cancer Institute in Detroit. "At the same time, soy isoflavones can also act as antioxidants in normal tissues, which protect them against unintended damage from the radiotherapy."

Human A549 non-small cell lung cancer (NSCLC) cells that were treated with soy isoflavones before radiation showed more DNA damage and less repair activity than cells that received only radiation.

The researchers used a formulation consisting of the three main isoflavones found in soybeans, including genistein, daidzein and glycitein. Previous research found pure genistein demonstrated antitumor activity in human NSCLC cell lines and enhanced the effects of EGFR-tyrosine kinase inhibitors. This study found the soy mixture had an even greater antitumor effect than pure genistein. The soy mixture also is consistent with the soy isoflavone pills used in clinical studies, which have been proven to be safe, researchers said.