Dec 19, 2013 10:00 AM
Jody Rosenblatt, PhD
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Huntsman Cancer Institute
The Renegades of Cell Biology: Researchers Discover Why K-Ras Gene Mutations Prove So Deadly in Cancer
SALT LAKE CITY—Cells with a mutation in the gene called K-Ras—found in close to 30% of all cancers, but mostly those with worst prognosis, such as pancreatic cancer, colon cancer, and lung cancer—behave in ways that subvert the normal mechanisms of cell death, according to a cell-culture study by researchers from Huntsman Cancer Institute (HCI) at the University of Utah.
Normal cells need survival signals from the tissue that surrounds them to remain alive. Other research has shown cells with the K-Ras mutation can survive and direct their own fate without these signals.
“Epithelia act as a skin that coat and protect most organs and are the sites where most solid tumors arise. Our previous studies showed that cells making up epithelia turnover at high rates due to mechanical pressure. When cells become too crowded (due to cells dividing), some cells pop out and die. The surprising thing we found in this study is that cells with the K-Ras mutations pop into the tissue and instead live,” said Jody Rosenblatt, PhD, an HCI investigator and associate professor in the Department of Oncological Sciences at the University of Utah who co-authored the study. The process of popping cells from epithelia is called extrusion, and in normal cells, this leads to cell death to keep the number of cells under control. “Our new study suggests that this oncogene subverts the mechanism of normal cell death to promote invasion”.
Another characteristic of cells with K-Ras mutations is that they consume parts of themselves (a process called autophagy) to keep up with the energy demands of rapid and unchecked cell division that the mutation causes.
“In normal cells that are about to extrude out, large quantities of an important signal called Sphingosine1-Phosphate (S1P) are present. Cells with the K-Ras mutation also produce S1P, but digest it through autophagy, so it cannot do its job and the cells extrude into the tissue,” said Gloria Slattum, doctoral candidate in the Rosenblatt Lab and lead author of the article. “When we blocked autophagy using a common anti-malaria drug called Chloroquine, the cells with K-Ras mutations extruded out of the tissue and died, just as normal cells do.”
The results were published online December 19 in the journal Current Biology.
Future study will investigate whether these cell-culture results hold true in an animal model. Co-authors of the article include Yapeng Gu, research associate in the Rosenblatt Lab, and Roger Sabbadini of LPath, Inc. The work was supported by a National Institute of Health (NIH) Innovator Award No. DP2 OD002056-01 and 1RO1GM102169-01, a NIH Developmental Biology Training Grant 5T32 HDO7491, and P30 CA042014 awarded to HCI for core facilities.
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About Huntsman Cancer Institute at the University of Utah
Huntsman Cancer Institute (HCI) is one of the world’s top academic research and cancer treatment centers. HCI manages the Utah Population Database - the largest genetic database in the world, with more than 16 million records linked to genealogies, health records, and vital statistics. Using this data, HCI researchers have identified cancer-causing genes, including the genes responsible for melanoma, colon and breast cancer, and paraganglioma. HCI is a member of the National Comprehensive Cancer Network (a 23-member alliance of the world's leading cancer centers) and is a National Cancer Institute-Designated Cancer Center. HCI treats patients with all forms of cancer and operates several high-risk clinics that focus on melanoma and breast, colon, and pancreas cancers. The HCI Cancer Learning Center for patient and public education contains one of the nation's largest collections of cancer-related publications. The institute is named after Jon M. Huntsman, Sr., a Utah philanthropist, industrialist, and cancer survivor.