July 22, 2014 - A gene responsible for stopping the movement of cancer from the lungs to other parts of the body has been discovered by researchers, indicating a new way to fight one of the worlds deadliest cancers. By identifying the cause of this metastasis -- which often happens quickly in lung cancer and results in a bleak survival rate -- Salk scientists are able to explain why some tumors are more prone to spreading than others. The newly discovered pathway, detailed today in Molecular Cell, may also help researchers understand and treat the spread of melanoma and cervical cancers.
"Lung cancer, even when it's discovered early, is often able to metastasize almost immediately and take hold throughout the body," says Reuben J. Shaw, Salk professor of molecular and cell biology and a Howard Hughes Medical Institute early career scientist. "The reason behind why some tumors do that and others don't has not been very well understood. Now, through this work, we are beginning to understand why some subsets of lung cancer are so invasive."
Lung cancer, which also affects nonsmokers, is the leading cause of cancer-related deaths in the country (estimated to be nearly 160,000 this year). The United States spends more than $12 billion on lung cancer treatments, according to the National Cancer Institute. Nevertheless, the survival rate for lung cancer is dismal: 80 percent of patients die within five years of diagnosis largely due to the disease's aggressive tendency to spread throughout the body.
To become mobile, cancer cells override cellular machinery that typically keeps cells rooted within their respective locations. Deviously, cancer can switch on and off molecular anchors protruding from the cell membrane (called focal adhesion complexes), preparing the cell for migration. This allows cancer cells to begin the processes to traverse the body through the bloodstream and take up residence in new organs.
In addition to different cancers being able to manipulate these anchors, it was also known that about a fifth of lung cancer cases are missing an anti-cancer gene called LKB1 (also known as STK11). Cancers missing LKB1 are often aggressive, rapidly spreading through the body. However, no one knew how LKB1 and focal adhesions were connected.