Why resistance to chemotherapy may develop

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SEATTLE, Aug. 6 (UPI) -- In a discovery U.S. scientists said was "completely unexpected," a protein was found to enable cancer cells to grow, invade tissue and resist chemotherapy.

Dr. Peter S. Nelson, a member of the Fred Hutchinson Cancer Research Center's Human Biology Division, said the research team from the University of Washington, the Oregon Health and Science University, the Buck Institute for Research on Aging and the Lawrence Berkeley National Laboratory found chemotherapy coaxed non-cancerous cells called fibroblasts to crank out the protein WNT16B within the tumor's vicinity, or micro-environment.

The high levels of this protein enable cancer cells to grow and resist chemotherapy. The researchers observed up to thirty-fold increases in WNT16B production, said Nelson, the study's senior author.

Nelson and colleagues found the fibroblasts, when exposed to chemotherapy, sustain DNA damage that drives the production of a broad spectrum of growth factors that stimulate cancer growth. Under normal circumstances, fibroblasts help maintain the structural integrity of connective tissue, and they play a critical role in wound healing and collagen production.

The WNT family of genes and proteins play an important role in normal development and also in the development of some cancers but, until now, was not known to play a significant role in treatment resistance, Nelson said.

The findings were published online in advance of the print edition of the journal Nature Medicine.