Nav: Home

Sleep apnea may make lung cancer more deadly

November 17, 2016

GLENVIEW, IL, November 17, 2016 - A team of researchers from the University of Chicago and the University of Barcelona has found that intermittent hypoxia, or an irregular lack of air experienced by people with sleep apnea, can increase tumor growth by promoting the release of circulating exosomes. Their results are published in the current issue of the journal CHEST.

Obstructive sleep apnea has been associated with increased incidence of cancer and mortality. In order to better understand the connection between the two, investigators took a detailed look at lung cancer tumor cell growth in mice. Half of the mice experienced regular breathing patterns, while the other half were exposed to intermittent hypoxia (IH) to simulate sleep apnea. The team found that exosomes released in the mice exposed to IH enhanced the malignant properties of the lung cancer cells.

Exosomes are microscopic spheres that transport proteins, lipids, mRNAs, and miRNAs between cells, similar to courier messengers delivering packages. They play a central role in cell-to-cell communication and are involved in promoting cancer cell growth. When exosomes increase in number and change their content, tumors become bigger and metastasize more easily.

"Exosomes are currently under intense investigation since they have been implicated in the modulation of a wide range of malignant processes," explained lead investigator David Gozal, MD, MBA, Department of Pediatrics, Pritzker School of Medicine, The University of Chicago, Chicago, IL. "Hypoxia can increase exosomal release and selectively modify exosome contents such as to enhance tumor proliferation and angiogenesis. We found the overall concentrations of plasma-isolated exosomes in IH-exposed mice were significantly increased."

Data revealed that exposing the mice to IH increased the number of cancer friendly exosomes. These exosomes increased the speed at which cancer cells replicated and promoted the movement of those cells throughout the body, disrupting the endothelial barrier and increasing the likelihood of metastasis. Researchers also found that when they isolated the exosomes from mice that had been exposed to IH, the extracted exosomes promoted malignant cell properties in vitro. Furthermore, exosomes from actual patients with sleep apnea showed the same effects on human cancer cells in culture when compared with exosomes from the same patients after treatment of their sleep apnea with CPAP.

"Over the past few years, exosomes have emerged as critically important players in intercellular communication," noted Dr. Gozal. "Notably, several studies have demonstrated the role of tumor exosomes in regulating major processes of tumor progression, such as angiogenesis, immune modulation, and metastasis."

Researchers also examined the miRNAs released by the exosomes and found differences in the miRNA from mice exposed to IH compared with those with regular breathing patterns. Eleven discrete miRNAs were identified, along with their gene targets inside the lung cancer cells. "The fact that IH elicits altered exosome miRNA content and selectively enhances specific properties of tumor biology provides a strong impetus and rationale for future studies in both mice and humans," commented Dr. Gozal.

Sleep apnea's variable oxygen levels cause damage that is detectable even at the tissue level. Although many other confounding factors exist, sleep apnea is shown to be an independent factor associated with adverse cancer outcomes. This study illustrates that exosomes, invigorated by IH, can influence tumors by facilitating their growth and helping them spread throughout the body, making cancer potentially more dangerous for patients who suffer from sleep apnea.

"There is no doubt," concluded Dr. Gozal, "that improved understanding of the complex network of genes and cellular signaling transduction pathways regulated by exosomal miRNAs in the context of obstructive sleep apnea will augment our knowledge on its potential deleterious effects among cancer patients."
-end-


Elsevier Health Sciences

Related Cancer Articles:

Radiotherapy for invasive breast cancer increases the risk of second primary lung cancer
East Asian female breast cancer patients receiving radiotherapy have a higher risk of developing second primary lung cancer.
Cancer genomics continued: Triple negative breast cancer and cancer immunotherapy
Continuing PLOS Medicine's special issue on cancer genomics, Christos Hatzis of Yale University, New Haven, Conn., USA and colleagues describe a new subtype of triple negative breast cancer that may be more amenable to treatment than other cases of this difficult-to-treat disease.
Metabolite that promotes cancer cell transformation and colorectal cancer spread identified
Osaka University researchers revealed that the metabolite D-2-hydroxyglurate (D-2HG) promotes epithelial-mesenchymal transition of colorectal cancer cells, leading them to develop features of lower adherence to neighboring cells, increased invasiveness, and greater likelihood of metastatic spread.
UH Cancer Center researcher finds new driver of an aggressive form of brain cancer
University of Hawai'i Cancer Center researchers have identified an essential driver of tumor cell invasion in glioblastoma, the most aggressive form of brain cancer that can occur at any age.
UH Cancer Center researchers develop algorithm to find precise cancer treatments
University of Hawai'i Cancer Center researchers developed a computational algorithm to analyze 'Big Data' obtained from tumor samples to better understand and treat cancer.
New analytical technology to quantify anti-cancer drugs inside cancer cells
University of Oklahoma researchers will apply a new analytical technology that could ultimately provide a powerful tool for improved treatment of cancer patients in Oklahoma and beyond.
Radiotherapy for lung cancer patients is linked to increased risk of non-cancer deaths
Researchers have found that treating patients who have early stage non-small cell lung cancer with a type of radiotherapy called stereotactic body radiation therapy is associated with a small but increased risk of death from causes other than cancer.
Cancer expert says public health and prevention measures are key to defeating cancer
Is investment in research to develop new treatments the best approach to controlling cancer?
UI Cancer Center, Governors State to address cancer disparities in south suburbs
The University of Illinois Cancer Center and Governors State University have received a joint four-year, $1.5 million grant from the National Cancer Institute to help both institutions conduct community-based research to reduce cancer-related health disparities in Chicago's south suburbs.
Leading cancer research organizations to host international cancer immunotherapy conference
The Cancer Research Institute, the Association for Cancer Immunotherapy, the European Academy of Tumor Immunology, and the American Association for Cancer Research will join forces to sponsor the first International Cancer Immunotherapy Conference at the Sheraton New York Times Square Hotel in New York, Sept.

Related Cancer Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Changing The World
What does it take to change the world for the better? This hour, TED speakers explore ideas on activism—what motivates it, why it matters, and how each of us can make a difference. Guests include civil rights activist Ruby Sales, labor leader and civil rights activist Dolores Huerta, author Jeremy Heimans, "craftivist" Sarah Corbett, and designer and futurist Angela Oguntala.
Now Playing: Science for the People

#520 A Closer Look at Objectivism
This week we broach the topic of Objectivism. We'll be speaking with Keith Lockitch, senior fellow at the Ayn Rand Institute, about the philosophy of Objectivism as it's taught through Ayn Rand's writings. Then we'll speak with Denise Cummins, cognitive scientist, author and fellow at the Association for Psychological Science, about the impact of Objectivist ideology on society. Related links: This is what happens when you take Ayn Rand seriously Another Critic Who Doesn’t Care What Rand Thought or Why She Thought It, Only That She’s Wrong Quote is from "A Companion to Ayn Rand"