By blocking protein, researchers keep brain tumors from repairing themselves
- Date:
- February 28, 2019
- Source:
- University of California - San Diego
- Summary:
- Researchers report inhibiting activity of a specific protein in glioblastomas boosts their sensitivity to radiation, improving treatment prospects for one of the most common and aggressive forms of brain cancer.
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Researchers at the San Diego branch of the Ludwig Institute for Cancer Research at University of California San Diego, with colleagues around the country, report that inhibiting activity of a specific protein in glioblastomas (GBM) boosts their sensitivity to radiation, thus improving treatment prospects for one of the most common and aggressive forms of brain cancer.
The findings are published in the February 28, 2019 on line issue of Cancer Cell.
GBM are extremely difficult to treat, with a median survival rate of 15 to 16 months, meaning that half of all patients survive to this length of time. Radiation and chemotherapy are the standard-of-care treatments, both intended to damage and destroy DNA in cancer cells, but their efficiency declines as tumors develop therapeutic resistance.
In their new paper, senior author Frank B. Furnari, PhD, professor of pathology at UC San Diego School of Medicine and member of Ludwig San Diego, first author Jianhui Ma, PhD, a postdoctoral fellow, and colleagues identified a mechanism used by GBM to promote therapeutic resistance: phosphorylation of a protein called phosphatase and tensin homolog or PTEN, which is encoded by the PTEN gene.
Normally, PTEN acts as a tumor suppressor, but mutations or modifications can produce the opposite effect. Specifically, the researchers found that phosphorylation of PTEN -- the adding of a phosphate molecule to an amino acid called tyrosine Y240 in cancer cells -- promoted DNA repair in tumors, reversing the effects of therapeutic radiation.
When scientists blocked Y240 phosphorylation in mouse models of GBM using inhibitors of the fibroblast growth factor receptor, the cancer cells became sensitive to radiation and more died, extending survival in the mice.
"These findings are novel and provide a foundation to move forward with a clinical trial and hopefully expand our findings to other cancer types that use this mechanism to evade therapy," said Furnari.
Story Source:
Materials provided by University of California - San Diego. Original written by Scott LaFee. Note: Content may be edited for style and length.
Journal Reference:
- Jianhui Ma, Jorge A. Benitez, Jie Li, Shunichiro Miki, Claudio Ponte de Albuquerque, Thais Galatro, Laura Orellana, Ciro Zanca, Rachel Reed, Antonia Boyer, Tomoyuki Koga, Nissi M. Varki, Tim R. Fenton, Suely Kazue Nagahashi Marie, Erik Lindahl, Timothy C. Gahman, Andrew K. Shiau, Huilin Zhou, John DeGroot, Erik P. Sulman, Webster K. Cavenee, Richard D. Kolodner, Clark C. Chen, Frank B. Furnari. Inhibition of Nuclear PTEN Tyrosine Phosphorylation Enhances Glioma Radiation Sensitivity through Attenuated DNA Repair. Cancer Cell, 2019; DOI: 10.1016/j.ccell.2019.01.020
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