Cigarette smoke is well recognised as a cause of lung cancer and is associated with many other forms of cancer in adults. Cigarette smoke has more than 4 000 components, many of which are linked to the development and progression of lung cancer. Evidence has shown second-hand smoke to be as dangerous as primary smoke due to its impact on the cells of the body.

In the new study, published online in the American Journal of Physiology – Lung Cell and Molecular Physiology, researchers found a cancer-causing agent called reactive oxygen species (ROS) present in the gaseous phase of cigarette smoke that has the ability to inhibit normal cell function. Exposure to the second-hand smoke produced by as little as two cigarettes was found to almost completely stop the function of a cell’s sodium pump within a few hours. In normal cells, the sodium pump plays a critical role transporting potassium into the cell and sodium out of the cell. The competence of the cell’s sodium pump, i.e., its inability to regulate sodium, is predictive of cell damage, disease progression and ultimately, survival.

“This is critical information with regard to second-hand smoke,” said Rajasekaran. “We now know that one need not inhale the particulate matter present in second-hand smoke to suffer the consequence of smoking. Exposure to the gaseous substance alone, which you breathe while standing near a smoker, is sufficient to cause harm.”

Dr Lee Goodglick, Associate Professor in the Department of Pathology and Laboratory Medicine, UCLA, and co-senior author of the study, noted, “Few reliable lung cancer biomarkers that could predict survival, treatment options or response to therapy exist today. Even fewer have been recognised where the function of the biomarker is known, yielding important information about the mechanism of action. This study really accomplishes both.”

This research is the latest finding in the compendium of evidence that supports protecting children from exposure to cigarette smoke. Excessive exposure to cigarette smoke during childhood can facilitate lung cancer development as children grow into adults. While more research is needed to understand the consequences of sodium pump inhibition by cigarette smoke, this study reveals that second-hand smoke is even more dangerous than previously thought.

Source: EurekAlert! March 2012