Reducing specific gene levels makes breast cancer cells more responsive to ionizing radiation

Reducing expression of a gene called BRCC36 that interacts with the breast cancer susceptibility gene 1 (BRCA1) makes breast cancer cells more responsive to ionizing radiation, according to scientists at Fox Chase Cancer Center in Philadelphia. The research was presented today at the 96th Annual Meeting of the American Association for Cancer Research (AACR) in Anaheim, Calif. BRCC36 directly interacts with the BRCA1 protein. Almost all invasive breast cancer cells have elevated BRCC36 levels compared to normal breast milk-duct cells.

“Since BRCC36 directly affects BRCA1 and BRCA1 is activated after exposure to radiation, we wanted to see if BRCC36 might be important in this response,” said Xiaowei Chen, Ph.D., a Fox Chase postdoctoral researcher in the laboratory of geneticist Andrew K. Godwin, Ph.D., and the study’s lead author.

Working with breast-cancer cell line MCF-7, the Fox Chase scientists reduced BRCC36 expression by 80 percent. They then exposed the cells to radiation, similar to that used in breast cancer treatment. They found that the number of breast cancer cells killed by the radiation increased by about 10 percent compared to cells that did not have their BRCC36 levels reduced.

“These findings hold promise for future breast cancer treatments,” Chen said. “BRCC36 may be a target to manage radiation-resistant breast cancer cells. Our next step is to find out why the cells with reduced BRCC36 are more sensitive to radiation.”