Oct. 21 (HealthDay News) -- U.S. researchers say they may have found a way to protect healthy tissue and also increase tumor death when cancer patients undergo radiation therapy.

The key is a biochemical signaling pathway that can influence how radiation exposure affects both healthy and cancerous cells. In experiments with mice, the researchers found that blocking a molecule called thrombospondin-1 from binding to its cell surface receptor (CD47) resulted in nearly total protection for normal tissue when exposed to standard and very high doses of radiation.

"We almost couldn't believe what we were seeing," study co-author Dr. Jeff S. Isenberg, an associate professor in the division of pulmonary, allergy and critical care medicine at the University of Pittsburgh School of Medicine, said in a news release.

"This dramatic protective effect occurred in skin, muscle and bone marrow cells, which is very encouraging. Cells that might have died of radiation exposure remained viable and functional when pre-treated with agents that interfere with the thrombospondin-1/CD47 pathway," Isenberg said.

The researchers also found that blocking this pathway delayed the regrowth of tumor cells after radiation exposure.

The findings were published Oct. 21 in the journal Science Translational Medicine.

Isenberg and colleagues are investigating the pathway's role in several other conditions, including hypertension, sickle cell disease, heart attack and wound healing.

SOURCE: University of Pittsburgh, news release, Oct. 21, 2009