Researchers believe they have found a gene responsible for a significant number of lung cancer diagnoses in “never smokers.” The study published in Lancet Oncology scanned the genomes of 2,272 participants who have never smoked, nearly 900 of whom were lung cancer patients, as well as healthy smokers.
“It has been very hard to do this research because never smokers have been mingled with smokers in past studies, and what usually pops up are genes related to nicotine dependence,” said Ping Yang, MD, PhD, a genetic epidemiologist at the Mayo Clinic and the study’s lead investigator.
The researchers report that about 30% of patients who never smoked and who developed lung cancer had the same uncommon variant, or allele, residing in a gene known as GPC5. In laboratory studies, researchers found that this allele leads to greatly reduced GPC5 expression, compared to normal lung tissue. The findings suggest that the gene has an important tumor suppressor-like function and that insufficient function can promote lung cancer development.
“This is the first gene that has been found that is specifically associated with lung cancer in people who have never smoked,” said Yang. “What’s more, our findings suggest GPC5 may be a critical gene in lung cancer development, and genetic variations of this gene may significantly contribute to increased risk of lung cancer.”
Little is known about the GPC5 gene, except that it can be over-expressed in multiple sclerosis, and that alternations in the genome where GPC5 is located are common events in a wide variety of human tumors. “It may be that GPC5 holds different roles depending on the tissue type during various disease development and progression,” said Yang.