Intermittent hypoxia increases melanoma metastasis to the lung in a mouse model of sleep apnea

Exosomal miR-106a-5p derived from intermittently hypoxic non-small-cell lung cancer increases tumor malignancy

Intermittent hypoxia (IH) is a hallmark of obstructive sleep apnea (OSA), which is related to tumorigenesis and progression. We explored the possible mechanisms by which OSA may promote the development of non-small cell lung cancer (NSCLC). In this study, NSCLC cells with and without miR-106a-5p inhibition were exposed to IH or room air (RA), and subsequently, exosomes were extracted and identified. Macrophages were incubated with these exosomes to detect the expression of the STAT3 signaling pathway and M2-type macrophage markers, as well as the effect of the macrophages on the malignancy of NSCLC cells. A nude mouse tumorigenesis model was constructed to detect the effects of exosomal miR-106a-5p on M2 macrophage polarization and NSCLC cell malignancy. Our results showed that IH exosomes promoted the polarization of M2 macrophages, thereby promoting the proliferation, invasion, and metastasis of NSCLC cells. Further, Based on microarray analysis of RA and IH exosomes, we discovered that miR-106a-5p, transferred to the macrophages through exosomes, participated in this mechanism by promoting M2 macrophage polarization via down-regulating PTEN and activating the STAT3 signaling pathway in vitro and in vivo. For patients with NSCLC and OSA, exosomal miR-106a-5p levels showed a positive relation to AHI. Exosomal miR-106a-5p represents a potential therapeutic target among patients with concomitant cancer and NSCLC.

Does obstructive sleep apnea increase the risk of cancer and cancer mortality in combined community-based cohorts?

Obstructive sleep apnea (OSA) has been linked to cancer in several clinical and community-based cohorts. The effect in community-based studies free of clinical referral bias needs to be replicated. In this observational prospective cohort study, we pooled data from three community-based prospective cohorts (Uppsala Sleep and Health in Men cohort [UMEN]; Sleep and health in women [SHE]; Men Androgen Inflammation Lifestyle Environment and Stress Cohort [MAILES]; nTotal = 1467). All cohorts had objective data on obstructive sleep apnea and registry linkage data on cancer and cancer mortality. Analyses for different obstructive sleep apnea measures (apnea-hypopnea index [AHI], oxygen desaturation index [ODI], and minimal saturation) as risk factors for cancer incidence (all cancers) were performed using Cox proportional hazards models (follow-up 5-16 years). We did not find an overall increased risk of cancer after adjustment for age, sex, and BMI (HRAHI [95% CI] = 1.00 [0.98; 1.01] and HRODI [95% CI] = 0.99 [0.97; 1.01]). Stratifying by daytime sleepiness did not influence the association. Cancer mortality was not significantly associated with obstructive sleep apnea. Taken together, we did not observe an overall increased risk of cancer or cancer mortality in relation to obstructive sleep apnea, however, our confidence limits remain wide for important diagnostic categories of sleep apnea severity. The relationship between obstructive sleep apnea and cancer needs further investigation in a comprehensive multi-cohort approach with greater statistical precision. For future studies we may need to find and then combine every community-based cohort study that can provide a definitive answer to the question on the risk of cancer from obstructive sleep apnea in the general population.

Association of obstructive sleep apnea symptoms with all-cause mortality and cause-specific mortality in adults with or without diabetes: A cohort study based on the NHANES

BACKGROUND

The association between obstructive sleep apnea syndrome (OSAS) and mortality has not been extensively researched among individuals with varying diabetic status. This study aimed to compare the relationship of OSAS with all-cause and cause-specific mortality in US individuals with or without diabetes based on data from the National Health and Nutrition Examination Survey (NHANES).

METHODS

The study included participants from the NHANES 2005-2008 and 2015-2018 cycles with follow-up information. OSAS data (OSAS.MAP10) was estimated from the questionnaire. Hazard ratios (HRs) and the 95% confidence interval (CI) of OSAS for mortality were calculated by Cox regression analysis in populations with different diabetes status. The relationships between OSAS and mortality risk were examined using survival curves and restricted cubic spline curves.

RESULTS

A total of 13 761 participants with 7.68 ± 0.042 follow-up years were included. In the nondiabetic group, OSAS.MAP10 was positively associated with all-cause, cardiovascular, and cancer mortality. In individuals with prediabetes, OSAS.MAP10 was positively related to all-cause mortality (HR 1.11 [95% CI: 1.03-1.20]) and cardiovascular mortality (HR 1.17 [95% CI: 1.03-1.33]). The relationship between OSAS.MAP10 and the risk of all-cause mortality and cancer mortality exhibited L-shaped curves in diabetes patients (both with nonlinear p values <.01). Further threshold effect analysis revealed that OSAS was positively related to death risk when OSAS.MAP10 exceeded the threshold scores.

CONCLUSION

The relationship between OSAS and mortality differed among participants with or without diabetes. Individualized clinical treatment plans should be developed in clinical practice to reduce the risk of death for patients with different metabolic conditions.

Small Extracellular Vesicles Harboring PD-L1 in Obstructive Sleep Apnea

Obstructive sleep apnea syndrome (OSA) has been associated with increased cancer incidence and aggressiveness. One hypothesis to support this association is the implication of immune response, particularly the programmed cell death pathway, formed by the receptor PD-1 and its ligand PD-L1. Recent studies have shown dysregulation of this pathway in severe OSA patients. It has also been shown that small extracellular vesicles (sEVs) carrying PD-L1 induce lymphocyte dysfunction. Thus, the aim of our study was to analyze the expression of PD-L1 on sEVs of OSA patients and to evaluate the role of sEVs on lymphocyte activation and cytotoxicity. Circulating sEVs were isolated from OSA patients and the control group. Lymphocytes were isolated from the control group. Circulating sEVs were characterized by western blot, nanotracking analysis, and flow cytometry and were incubated with lymphocytes. Our results show no differences in the quantity and composition of sEVs in OSA patients and no significant effects of sEVs in OSA patients on lymphocyte activation and cytotoxicity. These results suggest that OSA does not modify PD-L1 expression on sEVs, which does not contribute to dysregulation of cytotoxic lymphocytes.

Identification of key genes in chronic intermittent hypoxia-induced lung cancer progression based on transcriptome sequencing

BACKGROUND

Obstructive sleep apnea (OSA) is associated with increased risk of lung cancer mortality. Nevertheless, little is known about the underlying molecular mechanisms. This research aimed to investigate differentially expressed genes (DEGs) and explore their function in Lewis lung carcinoma (LLC)-bearing mice exposed to chronic intermittent hypoxia (CIH) by transcriptome sequencing.

METHODS

Lung cancer tissues in LLC-bearing mice exposed to CIH or normoxia were subjected for transcriptome sequencing to examine DEGs. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were employed to explore the function of DEGs. To evaluate the prognostic value of DEGs, the Kaplan-Meier survival analysis in combination with Cox proportional hazard model were applied based on The Cancer Genome Atlas.

RESULTS

A total of 388 genes with 207 up-regulated and 181 down-regulated genes were differentially expressed between the CIH and normoxia control groups. Bioinformatics analysis revealed that the DEGs were related to various signaling pathways such as chemokine signaling pathway, IL-17 signaling pathway, TGF-β signaling pathway, transcriptional misregulation in cancer, natural killer cell mediated cytotoxicity, PPAR signaling pathway. In addition, the DEGs including APOL1, ETFB, KLK8, PPP1R3G, PRL, SPTA1, PLA2G3, PCP4L1, NINJ2, MIR186, and KLRG1 were proven to be significantly correlated with poorer overall survival in lung adenocarcinoma.

CONCLUSIONS

CIH caused a significant change of gene expression profiling in LLC-bearing mice. The DEGs were found to be involved in various physiological and pathological processes and correlated with poorer prognosis in lung cancer.

Extracellular Vesicles Obtained From Lung Adenocarcinoma Cells Cultured Under Intermittent Hypoxia Induce M2 Macrophage Polarization via miR-20a-5p Delivery

Conclusion: These findings indicate that EVs obtained from lung adenocarcinoma cells cultured under IH deliver miR-20a-5p to promote M2 macrophage polarization by targeting PTEN.

Role of Sleep Apnea and Long-Term CPAP Treatment in the Prognosis of Patients With Melanoma: A Prospective Multicenter Study of 443 Patients

BACKGROUND

OSA has been associated with increased incidence and aggressiveness of melanoma. However, the long-term impact of OSA and CPAP treatment on the prognosis of melanoma remains unexplored.

RESEARCH QUESTION

Are OSA and CPAP treatment associated independently with a poor prognosis for cutaneous melanoma?

STUDY DESIGN AND METHODS

Four hundred forty-three patients with a diagnosis of cutaneous melanoma (2012-2015) underwent a sleep study within 6 months of diagnosis. The main 5-year outcome of the study was a composite of melanoma recurrence, metastasis, or mortality. Patients were divided into four groups: baseline apnea-hypopnea index (AHI) of fewer than 10 events/h (no OSA; control group), OSA treated with CPAP and good adherence, untreated or poor CPAP adherence in moderate (AHI, 10-29 events/h), and severe OSA (AHI, ≥ 30 events/h). Survival analysis was used to determine the independent role of OSA and CPAP treatment on melanoma composite outcome.

RESULTS

Three hundred ninety-one patients (88.2%) were available for analysis at 5-year follow-up (mean age, 65.1 ± 15.2 years; 49% male; Breslow index, 1.7 ± 2.5 mm). One hundred thirty-nine patients had AHI of fewer than 10 events/h (control group); 78 patients with OSA were adherent to CPAP; and 124 and 50 patients had moderate and severe OSA, respectively, without CPAP treatment. Median follow-up was 60 months (interquartile range, 51-74 months). During follow-up, 32 relapses, 53 metastases, and 52 deaths occurred (116 patients showed at least one of the main composite outcomes). After adjusting for age, sex, sentinel lymph nodes affected at diagnosis, BMI, diabetes, nighttime with an oxygen saturation below 90%, Breslow index, Epworth sleepiness scale scores, and melanoma treatment, moderate (hazard ratio [HR], 2.45; 95% CI, 1.09-5.49) and severe OSA (HR, 2.96; 95% CI, 1.36-6.42) were associated with poorer prognosis of melanoma compared with the control group. However, good adherence to CPAP avoided this excess risk (HR, 1.66; 95% CI, 0.71-3.90).

INTERPRETATION

Moderate to severe untreated OSA is an independent risk factor for poor prognosis of melanoma. Treatment with CPAP is associated with improved melanoma outcomes compared with untreated moderate to severe OSA.

Screening for obstructive sleep apnea in patients with cancer - a machine learning approach

Background

Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder associated with daytime sleepiness, fatigue, and increased all-cause mortality risk in patients with cancer. Existing screening tools for OSA do not account for the interaction of cancer-related features that may increase OSA risk.

Study Design and Methods

This is a retrospective study of patients with cancer at a single tertiary cancer institution who underwent a home sleep apnea test (HSAT) to evaluate for OSA. Unsupervised machine learning (ML) was used to reduce the dimensions and extract significant features associated with OSA. ML classifiers were applied to principal components and model hyperparameters were optimized using k-fold cross-validation. Training models for OSA were subsequently tested and compared with the STOP-Bang questionnaire on a prospective unseen test set of patients who underwent an HSAT.

Results

From a training dataset of 249 patients, kernel principal component analysis (PCA) extracted eight components through dimension reduction to explain the maximum variance with OSA at 98%. Predictors of OSA were smoking, asthma, chronic kidney disease, STOP-Bang score, race, diabetes, radiation to head/neck/thorax (RT-HNT), type of cancer, and cancer metastases. Of the ML models, PCA + RF had the highest sensitivity (96.8%), specificity (92.3%), negative predictive value (92%), F1 score (0.93), and ROC-AUC score (0.88). The PCA + RF screening algorithm also performed better than the STOP-Bang questionnaire alone when tested on a prospective unseen test set.

Conclusions

The PCA + RF ML model had the highest accuracy in screening for OSA in patients with cancer. History of RT-HNT, cancer metastases, and type of cancer were identified as cancer-related risk factors for OSA.

Does OSA Increase Risk for Cancer?: A Large Historical Sleep Clinic Cohort Study

BACKGROUND

The relationship between OSA and cancer is unclear.

RESEARCH QUESTION

What is the association between OSA and cancer prevalence and incidence in a large Western Australian sleep clinic cohort (N = 20,289)?

STUDY DESIGN AND METHODS

OSA severity was defined by apnea-hypopnea index (AHI) and nocturnal hypoxemia (duration and percentage at oxygen saturation < 90%) measured by in-laboratory polysomnogram. Measures of potential confounding included age, sex, BMI, smoking status, socioeconomic status, and BP. Outcomes were determined from the Western Australian cancer and death registries. Analyses were confined within periods using consistent AHI scoring criteria: January 1, 1989, to July 31, 2002 (American Sleep Disorders Association criteria), and August 1, 2002, to June 30, 2013 (Chicago criteria). We examined associations of AHI and nocturnal hypoxemia with cancer prevalence using logistic regression and cancer incidence using Cox regression analyses.

RESULTS

Cancer prevalence at baseline was 329 of 10,561 in the American Sleep Disorders Association period and 633 of 9,728 in the Chicago period. Nocturnal hypoxemia but not AHI was independently associated with prevalent cancer following adjustment for participant age, sex, BMI, smoking status, socioeconomic status, and BP. Of those without prevalent cancer, cancer was diagnosed in 1,950 of 10,232 (American Sleep Disorders Association) and 623 of 9,095 (Chicago) participants over a median follow-up of 11.2 years. Compared with the reference category (no OSA, AHI < 5 events per hour), univariable models estimated higher hazard ratios for cancer incidence for mild (AHI 5-15 events per hour), moderate (AHI 15.1-30 events per hour), and severe (AHI > 30 events per hour) OSA. Multivariable analyses consistently revealed associations between age and, in some cases, sex, BMI, and smoking status, with cancer incidence. After adjusting for confounders, multivariable models showed no independent association between OSA severity and increased cancer incidence.

INTERPRETATION

Nocturnal hypoxemia is independently associated with prevalent cancer. OSA severity is associated with incident cancer, although this association seems secondary to other risk factors for cancer development. OSA is not an independent risk factor for cancer incidence.

Intermittent hypoxia BMSCs-derived exosomal miR-31-5p promotes lung adenocarcinoma development via WDR5-induced epithelial mesenchymal transition

BACKGROUND

Intermittent hypoxia (IH) is a factor involved in the incidence and progression of lung adenocarcinoma (LUAD). Bone marrow-derived bone mesenchymal stem cells (BMSCs)-derived exosomes are related to the promotion of tumor development. The objective of this experiment was to clarify the mechanism of exosomes from BMSCs in promoting the progression of LUAD induced by IH.

METHODS

This study examined if IH BMSCS-derived exosomes affect the malignancy of LUAD cells in vitro. Dual-luciferase assays were conducted to confirm the target of miR-31-5p with WD repeat domain 5 (WDR5). We further investigated whether or not  exosomal miR-31-5p or WDR5 could regulate epithelial-mesenchymal transition (EMT). We determined the effect of IH exosomes using a tumorigenesis model in vivo.

RESULTS

miR-31-5p entered into LUAD cells via exosomes. MiR-31-5p was greatly upregulated in IH BMSCs-derived exosomes compared with RA exosomes. Increased expression of exosomal miR-31-5p induced by IH was discovered to target WDR5 directly, increased activation of WDR5, and significantly facilitated EMT, thereby promoting LUAD progression.

CONCLUSIONS

The promoting effect of IH on LUAD is achieved partly through BMSCs-derived exosomal miR-31-5p triggering WDR5 and promoting EMT.

Shared Lifestyle-Related Risk Factors of Cardiovascular Disease and Cancer: Evidence for Joint Prevention

Cardiovascular disease (CVD) and cancer are leading causes of mortality and morbidity worldwide and are the major focus of the World Health Organization's joint prevention programs. While, diverse diseases, CVD and cancer, have many similarities. These include common lifestyle-related risk factors and shared environmental, metabolic, cellular, inflammatory, and genetic pathways. In this review, we will discuss the shared lifestyle-related and environmental risk factors central to both diseases and how the strategies commonly used to prevent atherosclerotic vascular disease can be applied to cancer prevention.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Implications of obstructive sleep apnea in lung adenocarcinoma: A valuable omission in cancer prognosis and immunotherapy

Lung adenocarcinoma (LUAD) is a highly invasive malignant tumor with poor prognosis, and there is growing evidence that obstructive sleep apnea (OSA) could significantly promotes the risk of LUAD. In order to improve the treatment outcomes of patients with LUAD and OSA, we aim to screen OSA-related genes that may potentially affect LUAD and to discover a high sensitivity prognostic signature that can stratify LUAD/OSA patients and to further accurately identify LUAD patients who might respond to immunotherapy. Molecular subtypes classified by the prognostic signature did not belong to any previously reported subtypes of LUAD. The tumor microenvironment (TME), mutation, and so on, were significantly distinct between patients within different risk groups or clusters. Combined with gene set variation analysis (GSVA) and drug susceptibility analysis, patients in the low-risk group (The vast majority of patients belonging to cluster2 by molecular subtyping) were not suitable for immunotherapy due to T-cell exhaustion caused by long-term inflammatory response; the question of how to reverse T-cell exhaustion may be a primary consideration. Cluster3 patients had the highest benefit from immunotherapy, and although cluster1 patients had the worst prognosis, they were more sensitive to traditional chemotherapeutic drugs. Animal experiments showed that chronic intermittent hypoxia (CIH) could not only significantly promote the tumor growth of LUAD, but also increase the expression levels of risk genes. This risk model may contribute greatly to the evaluation of prognosis, molecular characteristics, and treatment modalities of LUAD/OSA, and could be further translated into clinical applications to ameliorate the treatment dilemmas.

Differential Impact of Intermittent vs. Sustained Hypoxia on HIF-1, VEGF and Proliferation of HepG2 Cells

Obstructive sleep apnea (OSA) is an emerging risk factor for cancer occurrence and progression, mainly mediated by intermittent hypoxia (IH). Systemic IH, a main landmark of OSA, and local sustained hypoxia (SH), a classical feature at the core of tumors, may act separately or synergistically on tumor cells. Our aim was to compare the respective consequences of intermittent and sustained hypoxia on HIF-1, endothelin-1 and VEGF expression and on cell proliferation and migration in HepG2 liver tumor cells. Wound healing, spheroid expansion, proliferation and migration were evaluated in HepG2 cells following IH or SH exposure. The HIF-1α, endothelin-1 and VEGF protein levels and/or mRNA expression were assessed, as were the effects of HIF-1 (acriflavine), endothelin-1 (macitentan) and VEGF (pazopanib) inhibition. Both SH and IH stimulated wound healing, spheroid expansion and proliferation of HepG2 cells. HIF-1 and VEGF, but not endothelin-1, expression increased with IH exposure but not with SH exposure. Acriflavine prevented the effects of both IH and SH, and pazopanib blocked those of IH but not those of SH. Macitentan had no impact. Thus, IH and SH stimulate hepatic cancer cell proliferation via distinct signaling pathways that may act synergistically in OSA patients with cancer, leading to enhanced tumor progression.

Obstructive Sleep Apnea: A Look towards Micro-RNAs as Biomarkers of the Future

Sleep-disordered breathing (SDB) includes a broad spectrum of diseases, of which obstructive sleep apnea syndrome (OSA) is the most clinically significant manifestation. OSA is a respiratory disorder characterized by episodes of complete or partial obstruction of the upper airways that disturb ventilation and sleep architecture. In recent years, interest in the clinical implications of OSA seems to have increased, probably due to the numerous studies that have shown the existence of an important correlation between OSA and cardiovascular, dysmetabolic, and neoplastic changes. The guidelines currently available highlight the importance of diagnosis and effective treatment for OSA, underlining the need for new biomarkers that are useful in clinical practice, feasible, and reproducible to guide medical decision making. In this review, we intend to provide an overview of the potential role of microRNAs as new indicators for OSA management. MicroRNAs (miRNAs) are small non-coding RNA molecules that play an important role in RNA silencing and regulation of gene expression at the post-transcriptional level. These can bind specifically to their target genes by forming silencing complexes, thus inducing degradation or altered gene expression. A wide range of miRNAs have been extensively studied in a variety of diseases including cancer, and recently, miRNAs have been shown to have enormous potential to function as diagnostic and clinical biomarkers of disease. This review includes recent studies that establish the inevitable role of miRNAs in the pathogenesis of OSA.

Intermittent hypoxia enhances the expression of hypoxia inducible factor HIF1A through histone demethylation

The cellular response to hypoxia is regulated through enzymatic oxygen sensors, including the prolyl hydroxylases, which control degradation of the well-known hypoxia inducible factors (HIFs). Other enzymatic oxygen sensors have been recently identified, including members of the KDM histone demethylase family. Little is known about how different oxygen-sensing pathways interact and if this varies depending on the form of hypoxia, such as chronic or intermittent. In this study, we investigated how two proposed cellular oxygen-sensing systems, HIF-1 and KDM4A, KDM4B, and KDM4C, respond in cells exposed to rapid forms of intermittent hypoxia (minutes) and compared to chronic hypoxia (hours). We found that intermittent hypoxia increases HIF-1α protein through a pathway distinct from chronic hypoxia, involving the KDM4A, KDM4B, and KDM4C histone lysine demethylases. Intermittent hypoxia increases the quantity and activity of KDM4A, KDM4B, and KDM4C, resulting in a decrease in histone 3 lysine 9 (H3K9) trimethylation near the HIF1A locus. We demonstrate that this contrasts with chronic hypoxia, which decreases KDM4A, KDM4B, and KDM4C activity, leading to hypertrimethylation of H3K9 globally and at the HIF1A locus. Altogether, we found that demethylation of histones bound to the HIF1A gene in intermittent hypoxia increases HIF1A mRNA expression, which has the downstream effect of increasing overall HIF-1 activity and expression of HIF target genes. This study highlights how multiple oxygen-sensing pathways can interact to regulate and fine tune the cellular hypoxic response depending on the period and length of hypoxia.

Chronic intermittent hypoxia, a hallmark of obstructive sleep apnea, promotes 4T1 breast cancer development through endothelin-1 receptors

The association between obstructive sleep apnea (OSA) and cancer is still debated and data are scarce regarding the link between OSA and breast cancer progression. Since conclusive epidemiological studies require large sample sizes and sufficient duration of exposure before incident cancer occurrence, basic science studies represent the most promising approach to appropriately address the topic. Here we assessed the impact of intermittent hypoxia (IH), the major hallmark of OSA, on the development of breast cancer and explored the specific involvement of the endothelin signaling pathway. Original in vitro and in vivo models were used where 3D-spheroids or cultures of murine 4T1 breast cancer cells were submitted to IH cycles, and nude NMRI mice, orthotopically implanted with 4T1 cells, were submitted to chronic IH exposure before and after implantation. The role of the endothelin-1 in promoting cancer cell development was investigated using the dual endothelin receptor antagonist, macitentan. In vitro exposure to IH significantly increased 4T1 cell proliferation and migration. Meta-analysis of 4 independent in vivo experiments showed that chronic IH exposure promoted tumor growth, assessed by caliper measurement (overall standardized mean difference: 1.00 [0.45-1.55], p < 0.001), bioluminescence imaging (1.65 [0.59-2.71]; p < 0.01) and tumor weight (0.86 [0.31-1.41], p < 0.01), and enhanced metastatic pulmonary expansion (0.77 [0.12-1.42]; p = 0.01). Both in vitro and in vivo tumor-promoting effects of IH were reversed by macitentan. Overall, these findings demonstrate that chronic intermittent hypoxia exposure promotes breast cancer growth and malignancy and that dual endothelin receptor blockade prevents intermittent hypoxia-induced tumor development.

Manuscript Title: A 4-miRNAs Serum Panel for Obstructive Sleep Apnea Syndrome Screening

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is a common chronic sleep disorder. OSAS is closely related to cardiovascular disease, metabolic disorders, cancer risk, and sudden death. This association has special significance in young people. Although it is known that OSAS has a great impact on physical health, it is estimated that 70-80% of patients with moderate-to-severe OSAS remain undiagnosed. Therefore, a new method for early diagnosis of the disease, the therapeutic effect of OSAS and prevention of complications to important.

METHODS

A total of 110 patients with moderate-to-severe OSAS diagnosed in the Sleep Disorders Diagnosis and Treatment Center of Peking University Shenzhen Hospital were selected. After excluding other diseases, 59 patients were finally selected as the OSAS group. In addition, 60 healthy people were selected as the control group. Serum RNA was then extracted. Eight RNA samples were randomly selected from the two groups for high-throughput miRNA sequencing. The 10 miRNAs with the greatest differences were selected as preselected markers from the results. Then, qRT-PCR was performed on the remaining RNA samples of the two groups to extract and verify the 10 miRNAs, and statistical analysis was performed between groups.

RESULTS

A diagnostic panel was constructed by a stepwise logistic regression model combined with the expression data of miRNAs in the validation phase. A four-miRNA panel was identified to better predict OSAS, and the model was calculated using the following formula: Logit (P)= 0.77-1.65 × miR-486-5p - 4.56 × miR-148a-3p + 1.79 × miR-744-5p + 1.13 × let-7d-3p. The AUC for the four-miRNA panel was 0.955 (95% CI: 0.899 to 0.985; sensitivity = 91.38%, specificity = 91.38%). Gene Ontology (GO) annotation and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis was included in bioinformatic analysis.

CONCLUSION

A 4-miRNAs panel as a diagnostic biomarker for OSAS screening is feasible.

Mechanical ventilation promotes lung tumor spread by modulation of cholesterol cell content

Mechanical stretch of cancer cells can alter their invasiveness. During mechanical ventilation, lungs may be exposed to an increased amount of stretch, but the consequences on lung tumors have not been explored. To characterize the influence of mechanical ventilation on the behavior of lung tumors, invasiveness assays and transcriptomic analyses were performed in cancer cell lines cultured in static conditions or under cyclic stretch. Mice harbouring lung melanoma implants were submitted to mechanical ventilation and metastatic spread was assessed. Additional in vivo experiments were performed to determine the mechano-dependent specificity of the response. Incidence of metastases was studied in a cohort of lung cancer patients that received mechanical ventilation compared with a matched group of non-ventilated patients. Stretch increases invasiveness in melanoma B16F10luc2 and lung adenocarcinoma A549 cells. We identified a mechanosensitive upregulation of pathways involved in cholesterol processing in vitro, leading to an increase in PCSK9 and LDLR expression, a decrease in intracellular cholesterol and preservation of cell stiffness. A course of mechanical ventilation in mice harboring melanoma implants increased brain and kidney metastases two weeks later. Blockade of PCSK9 using a monoclonal antibody increased cell cholesterol and stiffness and decreased cell invasiveness in vitro and metastasis in vivo In patients, mechanical ventilation increased PCSK9 abundance in lung tumors and the incidence of metastasis, thus decreasing survival. Our results suggest that mechanical stretch promote invasiveness of cancer cells, which may have clinically relevant consequences. Pharmacological manipulation of cholesterol endocytosis could be a novel therapeutic target in this setting.

The association of obstructive sleep apnea with melanoma incidence and mortality: a meta-analysis of 5,276,451 patients

BACKGROUND

Melanoma is the most aggressive and lethal form of skin cancer. While emerging in-vivo evidence suggests that intermittent hypoxia, a hallmark feature of obstructive sleep apnea (OSA), may induce melanoma tumorigenesis, the epidemiological association between OSA and melanoma has been inconsistent.

METHODS

We performed a literature search of PubMed, Embase, Scopus and Cochrane Library from inception until 6 June 2021. Two reviewers independently selected randomized trials or observational studies that reported the association of OSA with melanoma incidence or mortality in adults, in comparison to participants with no OSA. Two reviewers independently extracted relevant data and assessed the quality of evidence using the GRADE framework and the Newcastle-Ottawa Scale (NOS). We pooled data using an inverse variance-weighted meta-analysis and ran pre-specified subgrourp analyses.

RESULTS

The meta-analysis included six studies out of 1897 records, comprising a combined cohort of 5,276,451 patients. All studies were adjusted for covariates, with majority of studies adjusting for age (N=5) and sex (N = 4). Compared to those without OSA, patients with OSA had 71% higher pooled hazards of melanoma (HR = 1.71; 95% CI: 1.08-2.69, I² = 99%). Subgroup analyses for studies with (1) median follow-up duration of at least five years, (2) prospective study design, (3) adjustment for obesity yielded HRs of 1.88 (95%CI:1.32-2.67, N = 5), 1.11 (95%CI:0.77-1.60, N = 2) and 1.52 (95%CI:0.75-3.08, N = 3) respectively. One study investigating the relationship between OSA and melanoma mortality detected no association. There were insufficient studies to assess publication bias.

CONCLUSIONS

Meta-analysis of mainly retrospective observational studies, with significant heterogeneity, suggests increased melanoma incidence in OSA patients. Future studies should prospectively explore the differential risk of melanoma for varying OSA severity, and whether timely OSA treatment may mitigate this risk.

Polysomnographic Markers of Obstructive Sleep Apnea Severity and Cancer-Related Mortality: A Large Retrospective Multicenter Clinical Cohort Study

RATIONALE

The evidence for an association between cancer survival and obstructive sleep apnea (OSA) remains under-explored.

OBJECTIVES

To evaluate an association between markers of OSA severity (respiratory disturbances, hypoxemia, and sleep fragmentation) and cancer-related mortality in individuals with previously diagnosed cancer.

METHODS

We conducted a multicenter retrospective cohort study using linked clinical and provincial health administrative data on consecutive adults who underwent a diagnostic sleep study between 1994 and 2017 in four Canadian academic hospitals and were previously diagnosed with cancer through the Ontario Cancer Registry. Multivariable cause-specific Cox regressions were utilized to address the research objective.

RESULTS

We included 2,222 subjects. Over a median follow-up time of 5.6 years (IQR: 2.7-9.1), 261/2,222 (11.7%) individuals with prevalent cancer died from cancer-related causes, which accounted for 44.2% (261/590) of all-cause death. Controlling for age, sex, alcohol use disorder, prior heart failure, COPD, hypertension, diabetes, treatment for OSA, clinic site, year of the sleep study, and time since the cancer diagnosis, measures of hypoxemia and sleep fragmentation, but not apnea-hypopnea index were significantly associated with the cancer-specific mortality: % time spent with SaO2 <90% (HR per 5% increase: 1.05; 95% CI: 1.01-1.09); mean SaO2 (HR per 3% increase: 0.79; 0.68-0.92); and % of Stage 1 Sleep (HR per 16% increase: 1.27; 1.07-1.51).

CONCLUSION

In a large clinical cohort of adults with suspected OSA and previously diagnosed cancer, measures of nocturnal hypoxemia and sleep fragmentation as markers of OSA severity were significantly associated with cancer-related mortality, suggesting the need for more targeted risk awareness.

Heterogeneity of Melanoma Cell Responses to Sleep Apnea-Derived Plasma Exosomes and to Intermittent Hypoxia

Obstructive sleep apnea (OSA) is associated with increased cutaneous melanoma incidence and adverse outcomes. Exosomes are secreted by most cells, and play a role in OSA-associated tumor progression and metastasis. We aimed to study the effects of plasma exosomes from OSA patients before and after adherent treatment with continuous positive airway pressure (CPAP) on melanoma cells lines, and also to identify exosomal miRNAs from melanoma cells exposed to intermittent hypoxia (IH) or normoxia. Plasma-derived exosomes were isolated from moderate-to-severe OSA patients before (V1) and after (V2) adherent CPAP treatment for one year. Exosomes were co-incubated with three3 different melanoma cell lines (CRL 1424; CRL 1619; CRL 1675) that are characterized by genotypes involving different mutations in BRAF, STK11, CDKN2A, and PTEN genes to assess the effect of exosomes on cell proliferation and migration, as well as on pAMK activity in the presence or absence of a chemical activator. Subsequently, CRL-1424 and CRL-1675 cells were exposed to intermittent hypoxia (IH) and normoxia, and exosomal miRNAs were identified followed by GO and KEG pathways and gene networks. The exosomes from these IH-exposed melanoma cells were also administered to THP1 macrophages to examine changes in M1 and M2 polarity markers. Plasma exosomes from V1 increased CRL-1424 melanoma cell proliferation and migration compared to V2, but not the other two cell lines. Exposure to CRL-1424 exosomes reduced pAMPK/tAMPK in V1 compared to V2, and treatment with AMPK activator reversed the effects. Unique exosomal miRNAs profiles were identified for CRL-1424 and CRL-1675 in IH compared to normoxia, with six miRNAs being regulated and several KEGG pathways were identified. Two M1 markers (CXCL10 and IL6) were significantly increased in monocytes when treated with exosomes from IH-exposed CRL-1424 and CRL-1625 cells. Our findings suggest that exosomes from untreated OSA patients increase CRL-1424 melanoma malignant properties, an effect that is not observed in two other melanoma cell lines. Exosomal cargo from CRL-1424 cells showed a unique miRNA signature compared to CRL-1675 cells after IH exposures, suggesting that melanoma cells are differentially susceptible to IH, even if they retain similar effects on immune cell polarity. It is postulated that mutations in STK-11 gene encoding for the serine/threonine kinase family that acts as a tumor suppressor may underlie susceptibility to IH-induced metabolic dysfunction, as illustrated by CRL-1424 cells.

Lung cancer aggressiveness in an intermittent hypoxia murine model of postmenopausal sleep apnea

OBJECTIVE

Intermittent hypoxia (IH)-a hallmark of obstructive sleep apnea (OSA)-enhances lung cancer progression in mice via altered host immune responses that are also age and sex-dependent. However, the interactions of menopause with IH on tumor malignant properties remain unexplored. Here, we aimed to investigate lung cancer outcomes in the context of ovariectomy (OVX)-induced menopause in a murine model of OSA.

METHODS

Thirty-four female mice (C57BL/6, 12-week-old) were subjected to bilateral OVX or to Sham intervention. Six months after surgery, mice were pre-exposed to either IH or room air (RA) for 2 weeks. Then, 10 lung carcinoma (LLC1) cells were injected subcutaneously in the left flank, with IH or RA exposures continued for 4 weeks. Tumor weight, tumor invasion, and spontaneous lung metastases were assessed. Tumor-associated macrophages (TAMs) were isolated and subjected to flow cytometry polarity evaluation along with assessment of TAMs modulation of LLC1 proliferation in vitro. To determine the effect of IH and OVX on each experimental variable, a two-way analysis of variance was performed.

RESULTS

IH and OVX promoted a similar increase in tumor growth (∼2-fold; P = 0.05 and ∼1.74-fold; P < 0.05, respectively), and OVX-IH further increased it. Regarding lung metastasis, the concurrence of OVX in mice exposed to IH enhanced the number of metastases (23.7 ± 8.0) in comparison to those without OVX (7.9 ± 2.8; P < 0.05). The pro-tumoral phenotype of TAMS, assessed as M2/M1 ratio, was increased in OVX (0.06 ± 0.01; P < 0.01) and IH (0.06 ± 0.01; P < 0.01) compared with sham/RA conditions (0.14 ± 0.03). The co-culture of TAMS with naive LLC1 cells enhanced their proliferation only under IH.

CONCLUSION

In female mice, both the IH that is characteristically present in OSA and OVX as a menopause model emerge as independent contributors that promote lung cancer aggressiveness and seemingly operate through alterations in the host immune response.

Associations of self-reported obstructive sleep apnea with total and site-specific cancer risk in older women: a prospective study

BACKGROUND AND OBJECTIVES

Chronic intermittent hypoxia resulting from obstructive sleep apnea (OSA) may activate multiple carcinogenic pathways and lead to cancer development.

METHODS

We prospectively examined the association between OSA and cancer risk among 65,330 women in the Nurses' Health Study who were free of cancer in 2008 (mean age: 73.3 years). Incident cancer diagnoses were collected until 2016 and confirmed by pathology reports. Clinically diagnosed OSA was self-reported in 2008 and updated in 2012. We used time-dependent Cox regression to estimate hazard ratios (HR) for the associations of OSA with total and site-specific cancer risk.

RESULTS

We documented 5,257 incident cancer diagnoses during follow-up. In the age-adjusted model, OSA was associated with a 15% (95% CI: 1.03, 1.29) increase in total cancer risk. The association became nonsignificant after adjustment for multiple cancer risk factors (HR: 1.08; 95% CI: 0.96, 1.21). When examining cancer risk by site, OSA was associated with significantly increased risk for lung (fully adjusted HR: 1.52; 95% CI: 1.07, 2.17), bladder (fully adjusted HR: 1.94; 95% CI: 1.12, 3.35), and thyroid cancer (fully adjusted HR: 2.06; 95% CI: 1.01, 4.22) and possibly increased risk for kidney cancer (fully adjusted HR: 1.59; 95% CI: 0.84, 3.01). When grouping cancer sites by risk factor profiles, OSA was positively associated with smoking-related cancers (fully adjusted HR: 1.37; 95% CI: 1.11, 1.67), and this association was stronger in never smokers than ever smokers.

CONCLUSION

While OSA was not independently associated with overall cancer risk in older women, significant associations were observed for smoking-related cancers, especially in nonsmokers.

Differential effect of intermittent hypoxia and sleep fragmentation on PD-1/PD-L1 upregulation

Immunosurveillance is compromised in patients with obstructive sleep apnea (OSA) as reflected by overexpression of the programmed death cell receptor and its ligand (PD-1/PD-L1) coinhibitory axis. However, the contributions of intermittent hypoxia (IH) and sleep fragmentation (SF) are unclear. We therefore evaluated the expression of PD-1 and PD-L1 on immune cells from mice subjected to IH or SF, and in human cells exposed to IH, oxidative stress, or both conditions. Six-week-old male C57BL/6J mice were exposed to either IH or SF using previously established in vivo models. Moreover, human peripheral blood mononuclear cells (PBMC) were cultured overnight under normoxia, IH, hydrogen peroxide (H2O2), or both. Murine splenocytes and human PBMC were isolated, and labeled using surface-specific antibodies for flow cytometry analysis. Compared to control mice, IH induced higher expression of PD-L1 on F4/80 cells and of PD-1 on CD4+ and CD8+ T-cells, whereas no significant changes emerged after SF. In vitro models of IH and oxidative stress showed similar changes for expression of PD-L1 on human monocytes and PD-1 on CD4+ T-cells. Furthermore, H2O2 increased PD-1 expression on CD8+ T-cells, compromising their cytotoxic capacity assessed by perforin expression, similar to IH. No evidence of synergistic effects was apparent. Therefore, PD-1/PD-L1 upregulation reported in patients with OSA appears to be preferentially mediated by IH rather than SF.

Sodium Tanshinone IIA Sulfonate Attenuates Tumor Oxidative Stress and Promotes Apoptosis in an Intermittent Hypoxia Mouse Model

Objective:

Intermittent hypoxia, a significant feature of obstructive sleep apnea, has pro-tumorigenic effects. Here, we investigated the effect of sodium tanshinone IIA sulfonate on oxidative stress and apoptosis in a mouse model of Lewis lung carcinoma with intermittent hypoxia.

Methods:

Mice were randomly assigned to normoxia (control), normoxia plus sodium tanshinone IIA sulfonate (control + sodium tanshinone IIA sulfonate), intermittent hypoxia, and intermittent hypoxia + sodium tanshinone IIA sulfonate groups. Intermittent hypoxia administration lasted 5 weeks in the intermittent hypoxia groups. Lewis lung carcinoma cells were injected into the right flank of each mouse after 1 week of intermittent hypoxia exposure. Sodium tanshinone IIA sulfonate was injected intraperitoneally in the control + sodium tanshinone IIA sulfonate and intermittent hypoxia + sodium tanshinone IIA sulfonate groups. Tumor oxidative stress was evaluated by detection of malondialdehyde and superoxide dismutase. The apoptosis of tumor cells was evaluated by the terminal deoxynucleotidyl transferase dUTP nick-end labeling assay as well as by Western blot analysis of B-cell lymphoma 2-associated X protein and cleaved caspase-3 expression. Additionally, the expression of hypoxia-induced factor-1α, nuclear factor erythroid 2-related factor 2, and nuclear factor kappa B was also evaluated by Western blot.

Results:

Compared with the control group, the intermittent hypoxia treatment significantly increased Lewis lung carcinoma tumor growth and oxidative stress (serum malondialdehyde) but decreased serum levels of SOD and pro-apoptotic markers (terminal deoxynucleotidyl transferase dUTP nick-end labeling staining, B-cell lymphoma 2-associated X protein, and cleaved caspase-3). These changes were significantly attenuated by intraperitoneal injection of sodium tanshinone IIA sulfonate. Lower nuclear factor erythroid 2-related factor 2 and higher nuclear factor kappa B levels in the intermittent hypoxia group were clearly reversed by sodium tanshinone IIA sulfonate treatment. In addition, sodium tanshinone IIA sulfonate administration decreased the high expression of hypoxia-induced factor-1α induced by intermittent hypoxia.

Conclusion:

Intermittent hypoxia treatment resulted in high oxidative stress and low apoptosis in Lewis lung carcinoma–implanted mice, which could be attenuated by sodium tanshinone IIA sulfonate administration possibly through a mechanism mediated by the nuclear factor erythroid 2-related factor 2/nuclear factor kappa B signaling pathway.

Sleep Apnoea Adverse Effects on Cancer: True, False, or Too Many Confounders?

Obstructive sleep apnoea (OSA) is a prevalent disorder associated with increased cardiovascular, metabolic and neurocognitive morbidity. Recently, an increasing number of basic, clinical and epidemiological reports have suggested that OSA may also increase the risk of cancer, and adversely impact cancer progression and outcomes. This hypothesis is convincingly supported by biological evidence linking certain solid tumours and hypoxia, as well as by experimental studies involving cell and animal models testing the effects of intermittent hypoxia and sleep fragmentation that characterize OSA. However, the clinical and epidemiological studies do not conclusively confirm that OSA adversely affects cancer, even if they hold true for specific cancers such as melanoma. It is likely that the inconclusive studies reflect that they were not specifically designed to test the hypothesis or because of the heterogeneity of the relationship of OSA with different cancer types or even sub-types. This review critically focusses on the extant basic, clinical, and epidemiological evidence while formulating proposed directions on how the field may move forward.

Metabolic rivalry: circadian homeostasis and tumorigenesis

Circadian rhythms govern a large array of physiological and metabolic functions. Perturbations of the daily cycle have been linked to elevated risk of developing cancer as well as poor prognosis in patients with cancer. Also, expression of core clock genes or proteins is remarkably attenuated particularly in tumours of a higher stage or that are more aggressive, possibly linking the circadian clock to cellular differentiation. Emerging evidence indicates that metabolic control by the circadian clock underpins specific hallmarks of cancer metabolism. Indeed, to support cell proliferation and biomass production, the clock may direct metabolic processes of cancer cells in concert with non-clock transcription factors to control how nutrients and metabolites are utilized in a time-specific manner. We hypothesize that the metabolic switch between differentiation or stemness of cancer may be coupled to the molecular clockwork. Moreover, circadian rhythms of host organisms appear to dictate tumour growth and proliferation. This Review outlines recent discoveries of the interplay between circadian rhythms, proliferative metabolism and cancer, highlighting potential opportunities in the development of future therapeutic strategies.

Obstructive sleep apnea and cancer: a complex relationship

PURPOSE OF REVIEW

Obstructive sleep apnea (OSA) has been recognized as a risk factor for cancer mainly through hypoxia, based on studies that did not distinguish among cancer types. The purpose of this review is to discuss the most recent data on epidemiology and pathophysiology of the OSA-cancer association.

RECENT FINDINGS

According to epidemiological studies, OSA may have different influences on each type of cancer, either increasing or decreasing its incidence and aggressiveness. Time spent with oxygen saturation below 90% appears the polysomnographic variable most strongly associated with unfavorable effects on cancer. Experimental studies support the role of hypoxia as an important risk factor for cancer growth and aggressiveness, especially when it shows an intermittent pattern. These effects are largely mediated by the hypoxia-inducible factor, which controls the synthesis of molecules with effects on inflammation, immune surveillance and cell proliferation. Sleep fragmentation participates in increasing cancer risk. Modulating effects of age remain controversial.

SUMMARY

Effects of OSA on cancer may largely vary among neoplastic diseases, both in their magnitude and direction. The worse risk associated with intermittent rather than persistent hypoxia, and the effects of OSA therapy on cancer natural history are still poorly known, and deserve new careful studies.

The Association of Sleep Disorders, Obesity and Sleep-Related Hypoxia with Cancer

BACKGROUND

Sleep disorders have emerged as potential cancer risk factors.

OBJECTIVE

This review discusses the relationships between sleep, obesity, and breathing disorders with concomitant risks of developing cancer.

RESULTS

Sleep disorders result in abnormal expression of clock genes, decreased immunity, and melatonin release disruption. Therefore, these disorders may contribute to cancer development. Moreover, in sleep breathing disorder, which is frequently experienced by obese persons, the sufferer experiences intermittent hypoxia that may stimulate cancer cell proliferation.

DISCUSSION

During short- or long- duration sleep, sleep-wake rhythm disruption may occur. Insomnia and obstructive sleep apnea increase cancer risks. In short sleepers, an increased risk of stomach cancer, esophageal squamous cell cancer, and breast cancer was observed. Among long sleepers (>9 hours), the risk of some hematologic malignancies is elevated.

CONCLUSION

Several factors including insomnia, circadian disruption, obesity, and intermittent hypoxia in obstructive sleep apnea are contributing risk factors for increased risk of several types of cancers. However, further studies are needed to determine the more significant of these risk factors and their interactions.

Five-year relative survival in sleep apnea patients with a subsequent cancer diagnosis

STUDY OBJECTIVES

In vitro and animal studies suggest that intermittent hypoxia characterizing sleep apnea contributes to accelerated cancer progression. However, the impact of sleep apnea on survival subsequent to cancer diagnosis is unknown.

METHODS

We identified a cohort of 1,575 adults diagnosed with sleep apnea between 2005 and 2014 with a subsequent cancer diagnosis via linkage of the University of Washington Medicine system and a population-based cancer registry serving the same Seattle-Puget Sound region. We computed age-standardized 5-year relative survival after cancer diagnosis for all cancers combined, and for specific cancer sites, for both the sleep apnea cohort and the general Seattle-Puget Sound population, and we used US life tables as the reference population. Relative survival was estimated by sex, cancer stage, and health care engagement.

RESULTS

Five-year overall relative survival for cancer was more favorable in the sleep apnea cohort than in the general population [83.6%, 95% confidence interval (CI): 79.8%-86.8% vs 71.6%, 95% CI: 71.3%-71.9%]; this pattern was applicable to most specific cancer sites. However, 5-year relative survival was slightly less favorable in the sleep apnea cohort among patients with melanoma (97.7%, 95% CI: 84.6%-99.7% vs 99.2%, 95% CI: 98.8%-99.5%) and cancer of the corpus uteri (84.0%, 95% CI: 58.2%-94.5% vs 84.6%, 95% CI: 83.1%-86.0%).

CONCLUSIONS

The fact that survival after cancer, overall and for most cancer sites, was more favorable in patients with sleep apnea warrants larger community-based studies to further tease out effects of sleep apnea and treatment on site-specific survival for different cancer types, particularly in patients with melanoma or uterine cancer.

Short-term prognostic effects of circulating regulatory T-Cell suppressive function and vascular endothelial growth factor level in patients with non-small cell lung cancer and obstructive sleep apnea

OBJECTIVE

To determine if suppressive function of regulatory T-cells (Tregs) and vascular endothelial cell growth factor (VEGF) levels are closely associated with prognosis of patients with non-small cell lung cancer (NSCLC) and obstructive sleep apnea (OSA).

METHODS

Peripheral blood from 20 OSA patients, 44 newly diagnosed NSCLC patients with (n = 22) and without (n = 22) OSA was collected. Forkhead box protien 3 plus (Foxp3⁺) and CTLA-4⁺ Tregs ratio were analyzed with flow cytometry. Levels of VEGF, IL-10 and TGF-β₁ were analyzed with enzyme-linked immuno sorbent assay. NSCLC patients with and without OSA were followed up for two years. Optimal cutoff values were determined by receiver operating characteristic curves. Survival analysis were performed using the Kaplan-Meier test.

RESULTS

NSCLC patients with OSA showed higher Foxp3⁺Tregs ratio, higher plasma VEGF and TGF-β₁ levels when compared with NSCLC patients without OSA (P < 0.05). In NSCLC patients with OSA or not, subjects with higher Foxp3⁺Treg ratio, higher TGF-β₁ and VEGF levels tended to have poor mean survival time and two-year overall survival (OS, Foxp3⁺Treg: 636.7 vs. 704.8 days, 59.0% vs. 82.6%, P = 0.125; TGF-β₁: 637.8 vs. 698.4 days, 57.0% vs. 84.4%, P = 0.054; VEGF: 642.9 vs. 677.5 days, 48.6% vs. 81.3%, P = 0.074). Multivariate Cox regression adjusted for disease stage and receipt of systemic treatments, confirmed the links between high VEGF level and worse OS (HR: 1.003; 95% CI: 1.001-1.005; P = 0.021).

CONCLUSIONS

OSA may up-regulate the expression of circulating TGF-β₁, VEGF and Foxp3⁺Tregs expression in NSCLC patients. Elevated VEGF level is closely associated with worse short-term survival in NSCLC patients with OSA or not.

The Association of Sleep Apnea and Cancer in Veterans

Objective

To test the association between preexisting obstructive sleep apnea (OSA) and subsequent cancer in a large long-term cohort of veteran patients.

Study Design

Retrospective matched cohort study.

Setting

The Veterans Affairs Health Care System.

Subjects and Methods

All veteran patients diagnosed with OSA between 1993 and 2013 by International Classification of Diseases, Ninth Revision ( ICD-9) codes in any Veterans Affairs facility and veteran patients without an OSA diagnosis, matched to patients with OSA by age and index year. Cancer diagnoses were identified by ICD-9 codes for the time period at least 2 years after OSA diagnosis or index date. We tested the association between OSA and cancer using multivariate Cox regression with time since cohort entry as the time axis, adjusting for potential confounders.

Results

The cohort included 1,377,285 patients (726,008 with and 651,277 without an OSA diagnosis) with mean age of 55 years, predominantly male (94%), a minority obese (32%), and median follow-up of 7.4 years (range, 2.0-25.2). The proportion of patients diagnosed with cancer was higher in those with vs without an OSA diagnosis (8.3% vs 3.6%; mean difference 4.8%; 95% confidence interval [CI], 4.7%-4.8%; P < .001). After adjusting for age, sex, year of cohort entry, smoking status, alcohol use, obesity, and comorbidity, the hazard of incident cancer was nearly double in patients with vs without an OSA diagnosis (hazard ratio, 1.97; 95% CI, 1.94-2.00; P < .001).

Conclusion

Preexisting OSA was strongly associated with subsequent cancer in this veteran cohort, independent of several known cancer risk factors. These findings suggest that OSA may be a strong, independent risk factor for subsequent cancer development.

Morphological Characteristic of Melanoma B16 Progression in C57BL/6 Mice with High and Low Resistance to Hypoxia

The features of B16 melanoma progression in male C57BL/6 mice with initially high and low resistance to hypoxia were studied. To assess the resistance to hypoxia, the mice were placed in a low-pressure chamber at a simulated altitude of 10,000 m. One month after testing, B16 melanoma was inoculated to high- and low-resistant animals. In 19 days after melanoma transplantation, the severity of melanoma progression was assessed by morphological and immunofluorescent methods. The expression of vegf-a and hif-1a in the liver of melanomabearing and control mice was evaluated by real-time PCR. Tumor growth progression was more pronounced in low-resistant mice, which was seen from high weight of the primary tumor node, relative necrosis area, proliferation rates (mitotic index and number of Ki-67+ cells), and expression of vegf-a gene in the liver. In high-resistant to hypoxia animals, the number of caspase-3+ cells dying by apoptosis was higher. The data on more rapid melanoma progression in mice with low resistance to hypoxia should be considered during the search of new prognostic markers and methods for therapy of malignant neoplasms.

A Cell Culture Model that Mimics Physiological Tissue Oxygenation Using Oxygen-permeable Membranes

Dissolved oxygen and its availability to cells in culture is an overlooked variable which can have significant consequences on experimental research outcomes, including reproducibility. Oxygen sensing pathways play key roles in cell growth and behavior and pericellular oxygen levels should be controlled when establishing in vitro models. Standard cell culture techniques do not have adequate control over pericellular oxygen levels. Slow diffusion through culture media limits the precision of oxygen delivery to cells, making it difficult to accurately reproduce in vivo-like oxygen conditions. Furthermore, different types of cells consume oxygen at varying rates and this can be affected by the density of growing cells. Here, we describe a novel in vitro system that utilizes hypoxic chambers and oxygen-permeable culture dishes to control pericellular oxygen levels and provide rapid oxygen delivery to adherent cells. This procedure is particularly relevant for protocols studying effects of rapid oxygen changes or intermittent hypoxia on cellular behavior. The system is inexpensive and easily assembled without highly specialized equipment.

Circulating microRNA profile as a potential biomarker for obstructive sleep apnea diagnosis

Evaluation of microRNAs (miRNAs) could allow characterization of the obstructive sleep apnea (OSA) and help diagnose it more accurately. We aimed to examine circulating miRNA profiles to establish the differences between non-OSA and OSA patients. Additionally, we aimed to analyse the effect of continuous positive airway pressure (CPAP) treatment on the miRNA profile. This observational, longitudinal study included 230 subjects referred to the Sleep Unit due to suspected OSA. Expression profiling of 188 miRNAs in plasma was performed in 27 subjects by TaqMan-Low-Density-Array. OSA-related miRNAs were selected for validation by RT-qPCR in 203 patients. Prediction models were built to discriminate between non-OSA and OSA: 1) NoSAS-score, 2) differentially expressed miRNAs, and 3) combination of NoSAS-score plus miRNAs. The differentially expressed miRNAs were measured after 6 months of follow-up. From the 14 miRNAs selected for validation, 6 were confirmed to be differentially expressed. The areas under the curve were 0.73 for the NoSAS-score, 0.81 for the miRNAs and 0.86 for the combination. After 6 months of CPAP treatment, miRNA levels in the OSA group seem to approximate to non-OSA levels. A cluster of miRNAs was identified to differentiate between non-OSA and OSA patients. CPAP treatment was associated with changes in the circulating miRNA profile.

Severe depletion of peripheral blood dendritic cell subsets in obstructive sleep apnea patients: A new link with cancer?

Recent evidence suggests that alterations of the immune responses are associated with the inflammatory nature of obstructive sleep apnea (OSA) and of its related co-morbidities. In this scenario, we asked whether circulating dendritic cell (DC) subsets may be possible players as their role has not yet been detailed. The frequency distribution of peripheral blood myeloid (mDC1 and mDC2) and plasmacytoid (p) DCs was investigated by mean of multi-parametric flow cytometry in 45 OSA patients (mean age: 53 yrs; M = 29) at the time of the first diagnosis and compared to 30 age- and sex-matched healthy controls. Oxidative burst (OB) and serum levels of tumor necrosis factor (TNF)-α, (interleukin) (IL)-6, interferon (INF)-γ, IL-2, IL-4, IL-10 and vascular endothelial growth factor (VEGF) were also analyzed. All subsets of circulating DCs were significantly depleted in OSA patients as compared to healthy subjects (p < 0.01, in all instances), with mDC2 and pDC subtypes being more severely compromised. These findings were co-existing with higher levels of OB along with an increased expression of IL-6, IL-10, TNF-α, IFN-γ, and VEGF (p < 0.005 in all instances). In particular, IL6 levels were significantly higher (p = 0.013) in severe OSA patients (apnea/hypopnea index >30) and were inversely correlated with both mDC2 (r = -0.802, p < 0.007) and pDC (r = -0.317, p = 0.04) subsets. We first provide evidence for a constitutive reduction of all circulating DC subsets in OSA patients. Perturbation of DCs coexists with an inflammatory milieu and is negatively correlated with the expression of IL-6, which is actually recognized as a pivotal inhibitor of DC maturation. Future studies exploring the contribution of DCs in the pathogenesis of OSA and of its complications should be encouraged.

Acute and chronic hypoxia differentially predispose lungs for metastases

Oscillations in oxygen levels affect malignant cell growth, survival, and metastasis, but also somatic cell behaviour. In this work, we studied the effect of the differential expression of the two primary hypoxia inducible transcription factor isoforms, HIF-1α and HIF-2α, and pulmonary hypoxia to investigate how the hypoxia response of the vascular endothelium remodels the lung pre-metastatic niche. Molecular responses to acute versus chronic tissue hypoxia have been proposed to involve dynamic HIF stabilization, but the downstream consequences and the extent to which differential lengths of exposure to hypoxia can affect HIF-isoform activation and secondary organ pre-disposition for metastasis is unknown. We used primary pulmonary endothelial cells and mouse models with pulmonary endothelium-specific deletion of HIF-1α or HIF-2α, to characterise their roles in vascular integrity, inflammation and metastatic take after acute and chronic hypoxia. We found that acute hypoxic response results in increased lung metastatic tumours, caused by HIF-1α-dependent endothelial cell death and increased microvascular permeability, in turn facilitating extravasation. This is potentiated by the recruitment and retention of specific myeloid cells that further support a pro-metastatic environment. We also found that chronic hypoxia delays tumour growth to levels similar to those seen in normoxia, and in a HIF-2α-specific fashion, correlating with increased endothelial cell viability and vascular integrity. Deletion of endothelial HIF-2α rendered the lung environment more vulnerable to tumour cell seeding and growth. These results demonstrate that the nature of the hypoxic challenge strongly influences the nature of the endothelial cell response, and affects critical parameters of the pulmonary microenvironment, significantly impacting metastatic burden. Additionally, this work establishes endothelial cells as important players in lung remodelling and metastatic progression.

Intermittent hypoxia enhances the tumor programmed death ligand 1 expression in a mouse model of sleep apnea

Background

As a hallmark of obstructive sleep apnea (OSA), intermittent hypoxia (IH) promotes tumor progress. The high expression of programmed death 1 and programmed death ligand 1 (PD-L1) in tumor leads to immune evasion and subsequently aggravates tumor progress. This study aims to determine the tumor PD-L1 expression under the IH condition.

Methods

A total of 24 C57BL/6J mice were randomly assigned to the normoxia (control, CTL) group and the IH group. Mice in the IH group were subjected to the IH condition for 5 weeks. Lung cancer cells were injected into the flank of each mouse after 1 week of IH exposure. Tumor PD-L1 expression was detected by immunohistochemistry (IHC). Correlation between tumor weight, tumor volume, and expression of PD-L1 was analyzed.

Results

Compared to the CTL group, mice in the IH group had a high PD-L1 expression. The IH can enhance the tumor PD-L1 expression. Tumor weight, volume, and HIF-1α levels were closely associated with the PD-L1 expression in the IH group, while dissimilar findings were observed in the CTL group.

Conclusions

The IH enhances tumor PD-L1 expression in OSA mimicking mice. Additional studies are required to clarify the underlying mechanism.