Beijing: Scientists have identified a mechanism that explains how fine air pollution particles might cause lung cancer, according to a study published today in eLife.
The findings could lead to new approaches for preventing or treating the initial lung changes that lead to the disease.
Tiny, inhalable fine particulate matter (FPM) found in air pollutants has been recognized as a Group 1 carcinogen and a substantial threat to global health. However, the cancer-causing mechanism of FPM remains unclear.
"Despite its potential to cause mutations, recent research suggests that FPM does not directly promote – and may even inhibit – the growth of lung cancer cells," explains first author Zhenzhen Wang, an associate researcher at Nanjing University (NJU), Nanjing, China, who carried out the study between labs at NJU and the University of Macau.
"This suggests that FPM might lead to cancer through indirect means that support tumor growth. For example, some studies suggest FPM can prevent immune cells from moving to where they are needed."
To explore this possibility, Wang and the team collected FPM from seven different locations in China and studied its effects on the main immune cells that defend against tumor growth – called cytotoxic T-cells (CTLs). In mice administered with lung cancer cells that were not exposed to FPM, CTLs were recruited to the lung to destroy the tumor cells. By contrast, in the mice whose lungs were exposed to FPM, the infiltration of CTLs was delayed – potentially allowing the tumor cells to establish in lung tissue.
"The most surprising find was the mechanism by which this process occurred," Wang says. "The peroxidasin enzyme stuck to the FPM in the lung, which increased its activity. Taken together, this means that wherever FPM lands in the lung, increased peroxidasin activity leads to structural changes in the lung tissue that can keep immune cells out and away from growing tumor cells.", the News Medical reported.