An international effort to chart out the genetic landscape of lung cancer has turned up a host of surprises. These include an array of new genes, including one that manipulates the growth of cells needed for lung function.
This report on the aberrations in the genetic sequence of lung adenocarcinoma (the most common form of lung cancer) discovered 57 changes often linked with the tumors. Till now, only about a third of these changes are linked with the 15 genes already said to affect lung cancer.
Advertisement"It is important to find these alterations in the cancer genome because it can tell us about what causes cancer and how to treat it," informs Dr. Matthew Meyerson of the Broad Institute of the Massachusetts Institute of Technology and Harvard University. This study appears online in the journal Nature.
The most common change brought out in this systematic study controls as many as 12 percent of lung cancer tumors. "This is a cancer gene that is special for lung cells," Meyerson was quoted. The gene (NKX2-1), affects the activity of alveoli, which are tiny air bags in the lungs, which facilitate the exchange of oxygen and carbon dioxide. "If you have mice that lack this gene, they don't make alveoli and they can't breathe. They die when they are born," says Meyerson, who is also an associate professor at the Dana-Farber Cancer Institute in Boston.
The study proposes that this gene can morph into one that promotes the growth of lung cancer. This cancer kills more than 1 million people worldwide each year, including more than 150,000 in the United States.
The finds are the first part of the Tumor Sequencing Project, which has included genome researchers from Baylor College of Medicine in Houston, Washington University in St. Louis and several cancer research centers as well. The researchers hunted for common genetic changes among more than 500 tumor specimens. The study is based on the notion that most human cancers arise from changes in DNA that occur over time.
The researchers were on the look out for extra or missing pieces of DNA."It turns out that the most common change is a lung-cancer specific gene," Meyerson says referring to the NKX2-1 discovery.
The finding of extra copies of the HER2 gene; hallmark of an aggressive type of breast cancer, was quite rare. This gene is targeted with the drug Herceptin, made by Genentech. "It is not a new discovery but it points out that lung cancer could also be treated with Herceptin," Meyerson avers. Also found were extra copies of the gene that makes telomerase (an enzyme associated with aging and cancer).
The next step in this research will see sequencing of the genome for mutations specific to lung cancer. According to Meyerson, the work has been done though the analysis remains. "There's more good stuff coming and lots of it," he vouches.
The Tumor Sequencing Project hopes to ultimately lay the foundation for more cancer genome efforts, including The Cancer Genome Atlas, a project of the National Human Genome Research Institute and the National Cancer Institute. The latter aims to sequence a wide range of human cancers.