( The most common form of lung cancer may...)Most common lung cancers may begin in newly discovered cells

Working in a mouse model, the researchers isolated a novel type of lung cell that can divide into fresh copies of itself and into the two more specialized kinds of cells deep in the lung. Their experiments show that at the earliest stage of tumor development, the stem cell appears to be the first lung cells that respond to a cancer-causing mutation. The newly identified cell type fulfills all but one of the strictest criteria that scientists look for in defining adult stem cells.

The study is published in the June 17, 2005, issue of the journal Cell.

"The work of Bender Kim and colleagues represents not only a leap forward in our understanding of lung tumorigenesis, it also heralds the arrival of a valuable mouse model for identifying those cells that should be the targets of therapeutic intervention," wrote Anton Berns of The Netherlands Cancer Center in Amsterdam in an accompanying commentary in Cell.

The identification of the cells could lead to earlier diagnosis of lung cancer in people. Lung cancer is the leading cause of cancer-related death in the United States, in part because it is usually detected at an advanced stage. Patients in whom the disease has spread to other organs have a five-year survival rate of only two percent. In contrast, lung cancer detected at an early stage boasts a 50 percent survival rate over a five-year period.

"There are many similarities between stem cells and cancer," said first author Carla Bender Kim, a postdoctoral fellow in the lab of senior author Tyler Jacks, a Howard Hughes Medical Institute investigator at Massachusetts Institute of Technology. "Cancer cells can continue to divide many times. Likewise, stem cells can divide over the lifespan of the organism. Also, tumors are very heterogeneous, composed of many different cells,
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Source:Howard Hughes Medical Institute