"In this study, we investigated the interplay between cigarette smoke, DNA damage and repair, focusing on the Nucleotide Excision Repair (NER) protein Xeroderma Pigmentosum Group C (XPC)."
BUFFALO, NY – June 9, 2025 – A new research paper was published in Volume 16 of Oncotarget on May 20, 2025, titled " Cigarette smoke and decreased DNA repair by Xeroderma Pigmentosum Group C use a double hit mechanism for epithelial cell lung carcinogenesis ."
In this study, led by first author Nawar Al Nasralla and corresponding author Catherine R. Sears, from the Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Indianapolis and the Richard L. Roudebush Veterans Affairs Medical Center , researchers investigated how cigarette smoke and reduced DNA repair capacity contribute together to the development of lung cancer. They found that when a critical DNA repair protein called XPC is decreased and lung cells are exposed to cigarette smoke, the combination causes extensive damage and significantly increases cancer risk.
Non-small cell lung cancer (NSCLC) develops through both genetic and environmental factors. This study focused on how cigarette smoke affects the body's natural ability to repair DNA. The researchers studied the role of XPC, a protein essential for recognizing and repairing harmful DNA changes caused by tobacco smoke. They found that low levels of XPC — commonly seen in lung cancer patients — made lung cells less capable of repairing DNA. This made the cells unstable and more likely to become cancerous. These changes were most pronounced in normal lung cells, suggesting that the earliest stages of disease occur before cancer is even detected.
The findings support a "double hit" model, where both cigarette smoke and reduced DNA repair work together to drive cancer development. In laboratory experiments, normal lung cells with low XPC levels showed more damage and cell death after cigarette smoke exposure. By contrast, lung cancer cells were more resistant to smoke damage, even when XPC was low, indicating that critical changes had likely occurred earlier in the disease process.
"Our study suggests that cigarette smoke exposure leads to decreased XPC mRNA expression, exacerbates total and oxidative DNA damage, hinders NER, and may contribute to lung cancer development."
The study also showed that DNA repair ability declined significantly in healthy cells after smoke exposure, but this effect was not seen in cancer cells. In addition, the researchers confirmed that XPC gene activity was lower in actual lung tumor tissue compared to nearby healthy lung tissue. This pattern was consistent across both adenocarcinoma and squamous cell carcinoma, the two main types of NSCLC.
These results add to our understanding of how lung cancer begins at the molecular level. By showing how cigarette smoke and reduced DNA repair combine to create genetic instability, the research points toward new strategies for prevention. A better understanding of XPC's role could help identify high-risk individuals and inform future efforts to stop lung cancer before it begins.
Continue reading: DOI: https://doi.org/10.18632/oncotarget.28724
