New study throws a bad light on this widely used cancer therapy

Feb 15, 2012 08:46 GMT  ·  By
Radiations turn some normal breast cancer cells into radiation- and chemotherapy-resistant induced breast cancer stem cells
   Radiations turn some normal breast cancer cells into radiation- and chemotherapy-resistant induced breast cancer stem cells

A group of investigators in the United States has determined that radiation therapy may not be the best approach to treat breast cancer. Though the radiations kill off more than half of tumor cells every treatment, they also trigger changes in surviving cancer cells. These changes make them more resilient.

In other words, regular cancerous cells are turned into breast cancer stem cells, a more radiation - and chemotherapy-resistant class of cells that cannot easily be destroyed. This cellular population then sets the foundation for the recurrence of breast cancer, even if the original tumor is suppressed.

The study was carried out at the University of California in Los Angeles (UCLA) Jonsson Comprehensive Cancer Center's (JCCC) Department of Radiation Oncology. If verified, the discovery could have significant influence on how breast cancer is usually addressed.

One possible solution to this newly found problem would be to develop a chemical approach towards stopping this cellular transformation from occurring. If this can be achieved, then the beneficial effects of radiotherapy will no longer be counteracted by the development of breast cancer stem cells (BCSC).

Details of the new investigation were published in the February 13 early online issue of the esteemed scientific journal Stem Cells. The senior author of the paper was JCCC researcher, and UCLA associate professor of radiation oncology, Dr. Frank Pajonk.

“We found that these induced breast cancer stem cells (iBCSC) were generated by radiation-induced activation of the same cellular pathways used to reprogram normal cells into induced pluripotent stem cells (iPS) in regenerative medicine,” he explains.

“It was remarkable that these breast cancers used the same reprogramming pathways to fight back against the radiation treatment,” adds the investigators, who also holds an appointment at the UCLA Eli and Edythe Broad Center of Regenerative Medicine.

An added benefit of controlling the cellular transformation leading to the development of BCSC would be that the total amount of radiations currently used to treat breast cancer could decrease significantly.

During the new study, the UCLA team removed all naturally occurring BCSC from a breast tumor sample, and then irradiated it with the same amount of radiations it would normally receive during radiotherapy.

In response to irradiation, some of the cells that survived the radiations turned into iBCSC, which looked surprisingly similar to their natural counterparts.

“What is really exciting about this study is that it gives us a much more complex understanding of the interaction of radiation with cancer cells that goes far beyond DNA damage and cell killing. The study may carry enormous potential to make radiation even better,” Pajonk explains.

The National Cancer Institute, the California Breast Cancer Research Program and the US Department of Defense provided the funds necessary for this investigation.