Air Pollution Unmasked: How Air Pollution Fuels Lung Cancer Development

The Problem:

Air pollution is a major public health concern, and it has been linked to a range of health problems, including respiratory diseases, heart disease, and cancer. In particular, there is growing evidence that air pollution can promote the development of lung cancer. A new study published in NatureCommunications sheds light on how air pollution can promote lung cancer by altering the activity of genes that are involved in cell growth and division.

The Study:‍

Building upon existing research, this study looks at how air pollution and car exhaust can cause lung cancer. It goes deeper into understanding how mutant lung cells grow and develop. The researchers found a way to activate a pathway in the body that triggers inflammation, and they identified a possible target for treatments that could reduce the risk of tumors forming. These findings suggest new ways to decrease the chances of cancer spreading in people with mutant lung cells who are exposed to harmful pollutants.

The study was conducted by a team of researchers from across the world and suggests that exposure to environmental particulate matter measuring <2.5 μm (PM2.5) in the air contributes to the differences in rates of EGFR-driven lung cancer in different geographic areas. EGFR-driven lung cancer refers to a specific type of lung cancer where the EGFR (epidermal growth factor receptor) gene plays a significant role in its development and growth. This gene mutation can cause the cells in the lungs to grow and divide abnormally, leading to the formation of tumors. Understanding this specific type of lung cancer is important for developing targeted treatments that can specifically address the effects of the EGFR mutation. Read more about EGFR-driven lung cancer and a personalized treatment method here. PM2.5particles are a type of air pollution often produced by various sources, including vehicle emissions, industrial activities, and burning of fossil fuels. PM2.5 particles can be harmful when inhaled because their small size ( <2.5 μm) allows them to penetrate deep into our lungs, potentially causing respiratory problems, aggravating existing conditions like asthma, and contributing to other health issues. These differences in cancer rates are influenced by various factors, including genetics and occupational exposure. It is crucial to understand how these factors interact with particulate matter exposure to increase the risk of developing lung cancer.

The study leveraged a mouse model to investigate this relationship between particulate matter and lung cancer. While mice are inherently different from humans, they share many genetic, physiological, and anatomical similarities. The researchers made changes in the genes of mice to make their lung cells produce a specific mutant gene associated with cancer. Then, they exposed these mice to either particulate matter or phosphate buffered saline (PBS), a non toxic solution, for three weeks, and measured the amount of tumor growth in their lungs 10 weeks later. They observed that particulate matter exposure caused an increase in certain immune cells, particularly macrophages, in the lungs of both control and EGFR mutant mice, supporting the idea that particulate matter exposure leads to sustained infiltration of macrophages in the lungs even after the exposure period.

The findings indicate that when exposure to particulate matter in the air occurs in vivo with a specific genetic mutation (EGFR L858R), there is an increased ability of certain lung cells (AT2 cells) to function similarly to progenitors, or cells with the potential to develop into different cell types, that fuels tumorigenesis, or the formation of tumors. They also discovered that particulate matter in the air can cause a change in EGFR mutant AT2 cells that increase the chance of lung cancer development. This change is triggered by a cytokine protein called IL-1β, which is released by immune cells in response to infection or tissue damage. However, this effect is not seen when either particulate matter exposure or the genetic mutation occurs alone.

“Key takeaway: This study found that exposure to air pollution can promote lung cancer by altering gene activity which can lead to tumor promotion."

There is an urgent need for carcinogenic assays to identify potential tumor-promoting agents across different tissues and to understand tissue-specific mediators. The study also highlights the need for more research on how air pollution affects human health and action to be taken to decrease air pollutants. Such efforts may guide new screening paradigms in high-risk, under-served populations and molecularly targeted cancer prevention approaches to inhibit cancer initiation.

Until then, what can you do to protect yourself from air pollution? There are several steps you can take:

Breathe Easy: 6 Life-Saving Tips

1. Check the air quality index (AQI) in your area: The AQI is a measure of how polluted the air is in your area. You can check the AQI on websites like AirNow.gov or through local news outlets. If the AQI is high, try to limit your time outdoors.
2. Use an air purifier: An air purifier can help remove pollutants from the air inside your home. Look for a purifier with a HEPA filter, which can capture small particles like PM2.5.
3. Wear a mask: If you need to be outside when the AQI is high, consider wearing a mask that can filter out pollutants. Look for masks that are labeled N95 or N99, which can filter out small particles.
4. Avoid exercising outdoors when the AQI is high: Exercise increases your breathing rate, which means you'll inhale more pollutants if you exercise outdoors when the AQI is high.
5. Use public transportation or carpool: Cars and trucks are major sources of air pollution, so using public transportation or carpooling can help reduce your exposure to pollutants.
6. Support policies that reduce air pollution: Contact your elected officials and urge them to support policies that reduce air pollution, such as regulations on emissions from cars and factories.

By taking these steps, you can help protect yourself from the harmful effects of air pollution and support efforts to improve air quality in your community.

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References:

1. Hill, W., Lim, E.L., Weeden, C.E. et al. Lung adenocarcinoma promotion by air pollutants. Nature 616, 159–167 (2023). https://doi.org/10.1038/s41586-023-05874-3

2. Association, American Lung. “10 Tips to Protect Yourself from Unhealthy Air.” American LungAssociation. Accessed May 19, 2023. https://www.lung.org/clean-air/outdoors/10-tips-to-protect-yourself.
3. Zimmer, Dustin. “How to Protect Yourself from Air Pollution.” Carbon fund, November 3, 2022. https://carbonfund.org/how-to-protect-yourself-from-air-pollution/.