Chronic intermittent hypoxia promoted lung cancer stem cell-like properties via enhancing Bach1 expression

MiR-210-3p enhances intermittent hypoxia-induced tumor progression via inhibition of E2F3

PURPOSE

Intermittent hypoxia (IH) is a hallmark of obstructive sleep apnea (OSA), which is related to tumorigenesis and progression. Although micro-ribonucleic acid-210-3p (miR-210-3p) is correlated with hypoxia-induced tumor development, its role in the relationship between IH and tumor function remains poorly understood. The present work focused on elucidating the molecular mechanism through which miR-210-3p drives tumor progression under IH.

METHODS

MiR-210-3p levels were quantified within tumor samples from patients with lung adenocarcinoma who had or did not have OSA. Correlations between miR-210-3p and polysomnographic variables were analyzed. For in vitro experiments, miR-210-3p was inhibited or overexpressed via transfection under IH conditions. Cell viability, growth, invasion and migration assays were carried out. For in vivo modeling of IH using mouse xenografts, a miR-210-3p antagomir was intratumorally injected, tumor biological behaviors were evaluated, and reverse transcription-quantitative polymerase chain reaction (RT-qPCR), immunohistochemistry and western blot were carried out for detecting miR-210-3p and E2F transcription factor 3 (E2F3) expression.

RESULTS

For patients with lung adenocarcinoma and OSA, high miR-210-3p levels showed positive relation to polysomnographic variables, such as oxygen desaturation index, apnea-hypopnea index, and proportion of total sleep time with oxygen saturation in arterial blood < 90%. IH enhanced tumor viability, proliferation, migration, and invasion, downregulated E2F3 expression, and increased miR-210-3-p levels. miR-210-3p overexpression induced similar changes. These changes were reversed by miR-210-3p inhibition in vitro or miR-210-3p antagomir through intratumoral injection in vivo.

CONCLUSIONS

IH-induced tumor development is driven through miR-210-3p by E2F3 suppression. MiR-210-3p represents a potential therapeutic target among patients with concomitant cancer and OSA.

Transcriptional regulation of cancer stem cell: regulatory factors elucidation and cancer treatment strategies

Cancer stem cells (CSCs) were first discovered in the 1990s, revealing the mysteries of cancer origin, migration, recurrence and drug-resistance from a new perspective. The expression of pluripotent genes and complex signal regulatory networks are significant features of CSC, also act as core factors to affect the characteristics of CSC. Transcription is a necessary link to regulate the phenotype and potential of CSC, involving chromatin environment, nucleosome occupancy, histone modification, transcription factor (TF) availability and cis-regulatory elements, which suffer from ambient pressure. Especially, the expression and activity of pluripotent TFs are deeply affected by both internal and external factors, which is the foundation of CSC transcriptional regulation in the current research framework. Growing evidence indicates that regulating epigenetic modifications to alter cancer stemness is effective, and some special promoters and enhancers can serve as targets to influence the properties of CSC. Clarifying the factors that regulate CSC transcription will assist us directly target key stem genes and TFs, or hinder CSC transcription through environmental and other related factors, in order to achieve the goal of inhibiting CSC and tumors. This paper comprehensively reviews the traditional aspects of transcriptional regulation, and explores the progress and insights of the impact on CSC transcription and status through tumor microenvironment (TME), hypoxia, metabolism and new meaningful regulatory factors in conjunction with the latest research. Finally, we present opinions on omnidirectional targeting CSCs transcription to eliminate CSCs and address tumor resistance.

A review of obstructive sleep apnea and lung cancer: epidemiology, pathogenesis, and therapeutic options

Despite undeniable advances in modern medicine, lung cancer still has high morbidity and mortality rates. Lung cancer is preventable and treatable, and it is important to identify new risk factors for lung cancer, especially those that can be treated or reversed. Obstructive sleep apnea (OSA) is a very common sleep-breathing disorder that is grossly underestimated in clinical practice. It can cause, exacerbate, and worsen adverse outcomes, including death and various diseases, but its relationship with lung cancer is unclear. A possible causal relationship between OSA and the onset and progression of lung cancer has been established biologically. The pathophysiological processes associated with OSA, such as sleep fragmentation, intermittent hypoxia, and increased sympathetic nervous excitation, may affect normal neuroendocrine regulation, impair immune function (especially innate and cellular immunity), and ultimately contribute to the occurrence of lung cancer, accelerate progression, and induce treatment resistance. OSA may be a contributor to but a preventable cause of the progression of lung cancer. However, whether this effect exists independently of other risk factors is unclear. Therefore, by reviewing the literature on the epidemiology, pathogenesis, and treatment of lung cancer and OSA, we hope to understand the relationships between the two and promote the interdisciplinary exchange of ideas between basic medicine, clinical medicine, respiratory medicine, sleep medicine, and oncology.

Single-cell and bulk RNA sequencing data jointly reveals VDAC2's impacts on prognosis and immune landscape of NSCLC

Non-small cell lung cancer (NSCLC) is characterized by stronger metastatic ability and worse prognosis. In NSCLC, hypoxia is a major cause of invasion and metastasis through promoting angiogenesis. In present study, NSCLC cell clusters were extracted from single cell-sequencing dataset GSE131907, which were combined with hypoxia-related genes to group clusters. qRT-PCR and western blot were used to validate the expression of target gene. Nine NSCLC clusters were extracted, which were divided into two hypoxia-related subgroups, C1 and C2. Totally 101 differentially expressed prognostic genes were identified between subgroups. Of which, VDAC2 showed excellent prognostic value for NSCLC and was selected for further analysis. VDAC2 was upregulated in tumor samples in TCGA and was correlated with advanced stages. In vitro experiments validated this trend. Five crucial immune cells showed differential infiltration proportions between high and low VDAC2 expression groups. VDAC2 knockdown significantly inhibited the proliferation and invasion ability of NSCLC cells. Integrating single cell and bulk sequencing data as well as wet lab experiments, hypoxia-related VDAC2 exhibited important prognostic value and showed the promise of becoming immune-therapy target in NSCLC.

Sodium tanshinone IIA sulfonate inhibits tumor growth via miR-138 upregulation in intermittent hypoxia-induced xenograft mice

PURPOSE

We studied the functions of sodium tanshinone IIA sulfonate (TSA) in inducing tumor growth in obstructive sleep apnea (OSA)-mimicking intermittent hypoxia (IH) xenograft mice and the underlying potential molecular mechanism.

METHODS

RNA sequencing was conducted to screen the differentially expressed microRNAs in cell lines exposed to IH with or without TSA treatment. As part of the 5-week in vivo study, we treated xenograft mice with 8-h IH once daily. TSA and miR-138 inhibitors or mimics were administrated appropriately. In addition, we performed real-time quantitative polymerase chain reaction (RT-PCR), Western blotting, enzyme-linked immunosorbent assay (ELISA), immunohistochemistry (IHC), microvessel density (MVD), and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assays.

RESULTS

RNA sequencing and RT-PCR results demonstrated that TSA increased the levels of miR-138 under IH conditions in vitro. TSA reduced the IH-stimulated high levels of hypoxia-induced factor-1α and vascular endothelial growth factor. Furthermore, IH contributed to high tumor migration, invasion, MVD, and low apoptosis. TSA attenuated IH-mediated tumor proliferation, migration, invasion, MVD, and increased apoptosis, whereas miR-138 inhibitor interrupted the effect of TSA on treating IH-induced tumor behaviors.

CONCLUSIONS

OSA mimicking IH facilitates tumor growth and reduces miR-138 levels. TSA inhibits IH-induced tumor growth by upregulating the expression of miR-138.

Age Differences in the Association of Sleep Duration Trajectory With Cancer Risk and Cancer-Specific Mortality: Prospective Cohort Study

BACKGROUND

Baseline sleep duration is associated with cancer risk and cancer-specific mortality; however, the association between longitudinal patterns of sleep duration and these risks remains unknown.

OBJECTIVE

This study aimed to elucidate the association between sleep duration trajectory and cancer risk and cancer-specific mortality.

METHODS

The participants recruited in this study were from the Kailuan cohort, with all participants aged between 18 and 98 years and without cancer at baseline. The sleep duration of participants was continuously recorded in 2006, 2008, and 2010. Latent mixture modeling was used to identify shared sleep duration trajectories. Furthermore, the Cox proportional risk model was used to examine the association of sleep duration trajectory with cancer risk and cancer-specific mortality.

RESULTS

A total of 53,273 participants were included in the present study, of whom 40,909 (76.79%) were men and 12,364 (23.21%) were women. The average age of the participants was 49.03 (SD 11.76) years. During a median follow-up of 10.99 (IQR 10.27-11.15) years, 2705 participants developed cancers. Three sleep duration trajectories were identified: normal-stable (44,844/53,273, 84.18%), median-stable (5877/53,273, 11.03%), and decreasing low-stable (2552/53,273, 4.79%). Compared with the normal-stable group, the decreasing low-stable group had increased cancer risk (hazard ratio [HR] 1.39, 95% CI 1.16-1.65) and cancer-specific mortality (HR 1.54, 95% CI 1.18-2.06). Dividing the participants by an age cutoff of 45 years revealed an increase in cancer risk (HR 1.88, 95% CI 1.30-2.71) and cancer-specific mortality (HR 2.52, 95% CI 1.22-5.19) only in participants younger than 45 years, rather than middle-aged or older participants. Joint analysis revealed that compared with participants who had a stable sleep duration within the normal range and did not snore, those with a shortened sleep duration and snoring had the highest cancer risk (HR 2.62, 95% CI 1.46-4.70).

CONCLUSIONS

Sleep duration trajectories and quality are closely associated with cancer risk and cancer-specific mortality. However, these associations differ with age and are more pronounced in individuals aged <45 years.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR-TNRC-11001489; http://tinyurl.com/2u89hrhx.

The dual role of MiR-210 in the aetiology of cancer: A focus on hypoxia-inducible factor signalling

Tumorigenesis exemplifies the complex process of neoplasm origination, which is characterised by somatic genetic alterations and abnormal cellular growth. This multidimensional phenomenon transforms previously dormant cells into malignant equivalents, resulting in uncontrollable proliferation and clonal expansion. Various elements, including random mutations, harmful environmental substances, and genetic predispositions, influence tumorigenesis's aetiology. MicroRNAs (miRNAs) are now recognised as crucial determinants of gene expression and key players in several biological methods, including oncogenesis. A well-known hypoxia-inducible miRNA is MiR-210, which is of particular interest because of its complicated role in the aetiology of cancer and a variation of physiological and pathological situations. MiR-210 significantly impacts cancer by controlling the hypoxia-inducible factor (HIF) signalling pathway. By supporting angiogenesis, metabolic reprogramming, and cellular survival in hypoxic microenvironments, HIF signalling orchestrates adaptive responses, accelerating the unstoppable development of tumorous growth. Targeting several components of this cascade, including HIF-1, HIF-3, and FIH-1, MiR-210 plays a vital role in modifying HIF signalling and carefully controlling the HIF-mediated response and cellular fates in hypoxic environments. To understand the complexities of this relationship, careful investigation is required at the intersection of MiR-210 and HIF signalling. Understanding this relationship is crucial for uncovering the mechanisms underlying cancer aetiology and developing cutting-edge therapeutic approaches. The current review emphasises MiR-210's significance as a vital regulator of the HIF signalling cascade, with substantial implications spanning a range of tumor pathogenesis.

Hypoxia promotes conversion to a stem cell phenotype in prostate cancer cells by activating HIF-1α/Notch1 signaling pathway

PURPOSE

The hypoxic tumor microenvironment and the maintenance of stem cells are relevant to the malignancy of prostate cancer (PCa). However, whether HIF-1α in the hypoxic microenvironment mediates the transformation of prostate cancer to a stem cell phenotype and the mechanism have not been elucidated.

MATERIALS AND METHODS

Prostate cancer stem cells (PCSCs) from PC-3 cell lines were examined for the expression of CD44, CD133, ALDH1, HIF-1α, Notch1, and HES1. We observed the effect of knockdown HIF-1α in vitro and mice models and evaluated the impact of HIF-1α on the Notch1 pathway as well as stem cell dedifferentiation. The effects on sphere formation, cell proliferation, apoptosis, cell cycle, and invasive metastasis were evaluated.

RESULTS

In our study, hypoxia upregulated HIF-1α expression and induced a stem cell phenotype through activation of the Notch1 pathway, leading to enhanced proliferation, invasion, and migration of PCa PC-3 cells. The knockdown of HIF-1α significantly inhibited cell dedifferentiation and the ability to proliferate, invade and metastasize. However, the inhibitory effect of knocking down HIF-1α was reversed by Jagged1, an activator of the Notch1 pathway. These findings were further confirmed in vivo, where hypoxia could enhance the tumorigenicity of xenograft tumors by upregulating the expression of HIF-1α to activate the Notch1 pathway. In addition, the expression of HIF-1α and Notch1 was significantly increased in human PCa tissues, and high expression of HIF-1α correlated with the malignancy of PCa.

CONCLUSION

In a hypoxic environment, HIF-1α promotes PCa cell dedifferentiation to stem-like cell phenotypes by activating the Notch1 pathway and enhancing the proliferation and invasive capacity of PC-3 cells.

The dual role and mutual dependence of heme/HO-1/Bach1 axis in the carcinogenic and anti-carcinogenic intersection

INTRODUCTION

In physiological concentrations, heme is nontoxic to the cell and is essential for cell survival and proliferation. Increasing intracellular heme concentrations beyond normal levels, however, will lead to carcinogenesis and facilitate the survival of tumor cells. Simultaneously, heme in an abnormally high quantity is also a potent inducer of tumor cell death, contributing to its ability to generate oxidative stress on the cells by boosting oxidative phosphorylation and suppressing tumors through ferroptosis. During tumorigenesis and progression, therefore, heme works as a double-edged sword. Heme oxygenase 1 (HO-1) is the rate-limiting enzyme in heme catabolism, which converts heme into physiologically active catabolites of carbon monoxide (CO), biliverdin, and ferrous iron (Fe²⁺). HO-1 maintains redox equilibrium in healthy cells and functions as a carcinogenesis inhibitor. It is widely recognized that HO-1 is involved in the adaptive response to cellular stress and the anti-inflammation effect. Notably, its expression level in cancer cells corresponds with tumor growth, aggressiveness, metastasis, and angiogenesis. Besides, heme-binding transcription factor BTB and CNC homology 1 (Bach1) play a critical regulatory role in heme homeostasis, oxidative stress and senescence, cell cycle, angiogenesis, immune cell differentiation, and autoimmune disorders. Moreover, it was found that Bach1 influences cancer cells' metabolism and metastatic capacity. Bach1 controls heme level by adjusting HO-1 expression, establishing a negative feedback loop.

MATERIALS AND METHODS

Herein, the authors review recent studies on heme, HO-1, and Bach1 in cancer. Specifically, they cover the following areas: (1) the carcinogenic and anticarcinogenic aspects of heme; (2) the carcinogenic and anticarcinogenic aspects of HO-1; (3) the carcinogenic and anticarcinogenic aspects of Bach1; (4) the interactions of the heme/HO-1/Bach1 axis involved in tumor progression.

CONCLUSION

This review summarized the literature about the dual role of the heme/HO-1/Bach1 axis and their mutual dependence in the carcinogenesis and anti-carcinogenesis intersection.

A novel OSA-related model of intermittent hypoxia in endothelial cells under flow reveals pronounced inflammatory pathway activation

Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder characterized by recurrent episodes of upper airway obstruction and subsequent hypoxia. In patients with OSA, severity and number of these hypoxic events positively correlate with the extent of associated cardiovascular pathology. The molecular mechanisms underlying intermittent hypoxia (IH)-driven cardiovascular disease in OSA, however, remain poorly understood-partly due to the lack of adequate experimental models. Here, we present a novel experimental approach that utilizes primary human endothelial cells cultivated under shear stress. Oxygen partial pressure dynamics were adopted in our in vitro model according to the desaturation-reoxygenation patterns identified in polysomnographic data of severe OSA patients (n = 10, with 892 severe desaturations, SpO₂<80%). Using western blot analysis, we detected a robust activation of the two major inflammatory pathways ERK and NF-κB in endothelial cells, whereas no HIF1α and HIF2α protein stabilization was observed. In line with these findings, mRNA and protein expression of the pro-inflammatory adhesion and signaling molecule ICAM-1 and the chemokine CCL2 were significantly increased. Hence, we established a novel in vitro model for deciphering OSA-elicited effects on the vascular endothelium. First data obtained in this model point to the endothelial activation of pro-inflammatory rather than hypoxia-associated pathways in OSA. Future studies in this model might contribute to the development of targeted strategies against OSA-induced, secondary cardiovascular disease.

Shashen-Maidong Decoction inhibited cancer growth under intermittent hypoxia conditions by suppressing oxidative stress and inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Lung cancer is one of the most common malignant tumours and has become the leading cause of cancer-related deaths worldwide. Abnormal microcirculation during tumour growth leads to intermittent hypoxia (IH), which is responsible for promoting cancer cell proliferation and migration. Patients with advanced lung cancers show deficiency of both Qi and Yin Syndrome (DQYS) in TCM, and studies have confirmed that IH exposure is related to DQYS. Shashen-Maidong Decoction (SMD), has been widely applied clinically targeting DQYS and has a long history for treating lung cancer by nourishing the body's "zheng qi" and resisting "xie qi". However, whether SMD could be beneficial to lung cancer under IH conditions remains unclear.

AIM OF THE STUDY

This study aimed to clarify the effects and mechanism of SMD on non-small cell lung cancer (NSCLC) growth under IH conditions.

MATERIALS AND METHODS

C57 mice were injected subcutaneously into the right axilla with Lewis lung cancer (LLC) cells and exposed to IH conditions (21%-5% O2, 5 min/cycle, 8 h/day) for 21 days. SMDs were orally treated with different concentrations (2.6, 5.2 or 10.4 g/kg/day) 30 min before IH exposure. Tumour proliferation and migration were assessed by HE and IHC staining, and oxidative stress was assessed by DHE staining and MDA or SOD detection. IL-6, IL-1β and TNF-α levels were assessed by IHC staining, and the IL-6/JAK2/STAT3 signalling pathway was detected by western blotting.

RESULTS

Our results showed that SMD treatment inhibited tumour growth and liver metastasis in LLC-bearing mice exposed to IH, decreased Ki67, CD31, VEGF, and MMP-2, and increased E-cadherin expression in tumourt tissue. SMD reduced ROS production, increased SOD levels and SOD-2 expression, and decreased MDA levels and NOX-2 expression. SMD decreased IL-6, IL-1β and TNF-α levels, reduced IL-6 expression and inhibited JAK2 and STAT3 phosphorylation. Additionally, SMD treatment improved DQYS and liver and kidney function in LLC-bearing mice under IH conditions.

CONCLUSION

Our research suggests that SMD treatment can inhibit tumour growth in mice exposed to IH. The antitumour effect of SMD may be related to attenuated oxidative stress and inflammation through inactivation of the IL-6/JAK2/STAT3 signalling pathway under IH conditions.

Hypoxia increases RCC stem cell phenotype via altering the androgen receptor (AR)-lncTCFL5-2-YBX1-SOX2 signaling axis

Background

Early studies indicated that the androgen receptor (AR) could promote renal cell carcinoma (RCC) development and metastasis, but its linkage to RCC progression under hypoxia, remains unclear.

Results

Here we found AR expression in RCC cells decreased in response to hypoxia, which might then lead to increase the cancer stem cells (CSC) phenotype through the lncTCFL5-2-modulated YBX1/SOX2 signals. The consequences of such hypoxia-modulated AR/lncTCFL5-2/YBX1/SOX2 signals ablity to alter the CSC phenotype might render RCC cells more resistant to targeted therapy with Sunitinib. Mechanism dissection revealed that AR might alter the lncTCFL5-2/YBX1/SOX2 signaling through transcriptional suppression of the lncTCFL5-2 expression via the AR-response-elements (AREs) on the lncTCFL5-2 promoter. The lncTCFL5-2 interacts with YBX1 to increase its stability, which in turn increases SOX2 expression at a transcriptional level via the YBX1-response-elements (YBX1Es) on the SOX2 promoter. The in vivo mouse model with orthotopic xenografts of RCC cells also validates the in vitro data, and a human RCC sample survey demonstrated the clinical significance of the AR/lncTCFL5-2/YBX1/SOX2 signaling axis for the RCC prognosis, likely as a result of regulating CSC phenotypes.

Conclusions

Together, these findings suggest that hypoxia may increase the RCC CSC phenotype via altering the AR/lncTCFL5-2/YBX1/SOX2 signaling axis and a potential therapy to target this newly identified signal perhaps may help improve the targeted therapy with Sunitinib to better suppress RCC progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00912-5.

Transcriptomic Profiling Analysis of Castration-Resistant Prostate Cancer Cell Lines Treated with Chronic Intermittent Hypoxia

Simple Summary

Prostate cancer is the second most frequently diagnosed cancer and the fifth cause of cancer mortality among men. Although localized and confined tumors are relatively curable, patients with advanced metastatic prostate cancer are still problematic. Hypoxia, which is a marked characteristic of advanced solid tumors, has been suggested to induce the progression of prostate cancer. This study aimed to evaluate the impact of chronic intermittent hypoxia on a castration-resistant prostate cancer cell line in inducing cancer progression using RNA sequencing analysis. Through RNA sequencing analysis, we prove that COL13A1, which is a key factor for the progression of metastasis, is closely related to metastatic prostate cancer. These results suggest that our findings indicate a novel strategy for the clinical management of mCRPC.

Abstract

Castration-resistant prostate cancer (CRPC) is still a major concern in men’s health, with 375,000 cancer deaths annually. Hypoxia, which is a marked characteristic of advanced solid tumors, has been suggested to induce prostate cancer towards CRPC, metastasis and treatment resistance. To evaluate the effect of hypoxia on prostate cancer, two and five cycles of hypoxia and reoxygenation were administered using 22Rv1 cell lines and denominated as 22Rv1-CI and 22Rv1-PCI, respectively. Cancer cell migration was promoted in 22Rv1-CI compared to controls, and the expression of COL13A1 was significantly up-regulated in 22Rv1-CI according to differentially expressed gene analysis of RNA sequencing among groups. Cancer cell migration was impeded in a wound healing assay after transfecting si-COL13A1. Moreover, the expression of COL13A1 was also higher in the cell line originating from bone metastatic prostate cancer compared to other cell lines. Using the open database GEO, we also confirmed that the expression of COL13A1 was higher in bone metastatic prostate cancer tissue than in localized prostate cancer tissue in patients. Therefore, COL13A1 may be closely related to the bony metastasis of prostate cancer, and our findings may provide valuable information on the pathophysiology of the metastatic niche induced by hypoxia in patients with CRPC.

Effect of chronic intermittent hypoxia-induced HIF-1α/ATAD2 expression on lung cancer stemness

Background

Obstructive sleep apnea is associated with increased lung cancer incidence and mortality. Cancer stem cells (CSCs) are characterized by their self-renewing ability, which contributes to metastasis, recurrence, and drug resistance. ATPase family AAA domain-containing protein 2 (ATAD2) induces malignancy in different types of tumors. However, a correlation between ATAD2 expression and CSCs in lung cancer has not yet been reported.

Methods

The relative messenger RNA (mRNA) levels of ATAD2, CD44, CD133, and hypoxia-inducible factor (HIF)-1α were determined using reverse-transcription quantitative polymerase chain reaction. ATAD2 protein levels were determined using Western blotting. Cell counting kit-8, 5-ethynyl-2′-deoxyuridine (EdU), and colony formation assays were performed to analyze the proliferation of lung cancer cells. Transwell migration and invasion assays were performed to evaluate cell migration and invasion, respectively. Tumor sphere formation analysis was used to determine tumor spheroid capacity. The link between ATAD2 and HIF-1α was verified using a dual-luciferase reporter assay. Immunofluorescence staining was performed to assess mitochondrial reactive oxygen species (mtROS) production. Flow cytometry analysis was conducted to determine the CD133 and CD44 positive cell ratio.

Results

We evaluated the relative expression of ATAD2 in four lung cancer cell lines (A549, SPC-A1, H460, and H1299 cells) and found increased mRNA and protein levels of ATAD2 in lung cancer samples. ATAD2 overexpression was a poor prognostic factor for lung cancer patients. Loss of ATAD2 reduced lung cancer cell viability and proliferation. Additionally, ATAD2 knockdown repressed lung cancer cell migration, invasion, stem-cell-like properties, and mtROS production. Chronic intermittent hypoxia (CIH)-induced HIF-1α expression significantly activated ATAD2 during lung cancer progression.

Conclusions

This study found that CIH induced HIF-1α expression, which acts as a transcriptional activator of ATAD2. The present study also suggests a novel mechanism by which the integrity of CIH-triggered HIF-1α/ATAD2 may determine lung cancer aggressiveness via the interplay of mtROS and stemness in lung cancer cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11658-022-00345-5.

Sleep-disordered breathing and risk of lung cancer: a meta-analysis longitudinal follow-up studies

Consensus remains lack regarding whether sleep-disordered breathing (SDB) is an independent risk factor for lung cancer. We therefore conducted a meta-analysis to clarify the relationship of SDB and lung cancer. Longitudinal follow-up studies investigating the association between SDB and incidence of lung cancer were included by search of electronic databases including PubMed, Embase, and Cochrane's Library. A random-effects model was adopted to combine the results. Seven studies were included. Pooled results showed that presence of SDB was independently associated with higher incidence of lung cancer [adjusted risk ratio (RR): 1.28; 95% confidence interval (CI), 1.11-1.47; P < 0.001; I2 = 37%]. Sensitivity analysis limited to studies with adjustment of smoking showed consistent results (three studies, RR: 1.34; 95% CI, 1.22-1.48; P < 0.001; I2 = 8%). Subgroup analysis suggested that the association between SDB and higher risk of lung cancer was not significantly affected by study characteristics such as study design, source of population, sample size, evaluation methods for SDB, follow-up duration, methods for validation of lung cancer, or score of study quality (P values for subgroup difference all >0.05). No significant publication bias was observed (P for Egger's regression test = 0.258). These results suggested that SDB may be an independent risk factor of lung cancer in adult population. Intensive screening and prevention of lung cancer in subjects with SDB should be considered.

MiR-142-3p as an Indicator of OSA Severity Predicts Prognosis in Lung Adenocarcinoma with OSA

PURPOSE

The aim was to explore the correlation between Obstructive sleep apnea (OSA) and Lung adenocarcinoma malignant prognosis and evaluate the miR-142-3p was used as an OSA severity indicator to predict the prognosis of Lung adenocarcinoma patients.

METHODS

This study comprised of 21 diagnosed lung adenocarcinoma patients with or without OSA. The sleep-related variables and tumor pathology were recorded. Hypoxia-inducible factor-1α (HIF1α) and ki67 expression were analyzed by immunohistochemistry in tumor samples. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to assess the level of miR-142-3p.

RESULTS

Lung adenocarcinoma with OSA showed higher apnea-hypopnea index (AHI), oxygen desaturation index (ODI), and the lower lowest pulse oxygen saturation (LS_PO₂) compared to Lung adenocarcinoma without OSA (P<0.05), and patients with severer OSA have an advanced TNM stage (P=0.004) and metastasis rate (p=0.032). In addition, OSA may down-regulate the miR-142-3p expression in patients with Lung adenocarcinoma, and the patients with low miR-142-3p expression exhibited severe OSA. MiR-142-3p levels significantly decreased in the advanced TNM stage (p=0.015), and the expression of miR-142-3p was negatively associated with AHI (r= -0.505, p=0.020), ODI (r= -0.513, p=0.017).

CONCLUSION

OSA severity may increase Lung adenocarcinoma malignant prognosis. OSA may down-regulate the expression of miR-42-3p. The expression of miR-142-3p was inversely correlated with AHI and ODI as a surrogate of OSA severity. Additionally, the low miR-142-3p expression level was significantly associated with advanced TNM stage in Lung adenocarcinoma patients.

BTB and CNC homology 1 (Bach1) induces lung cancer stem cell phenotypes by stimulating CD44 expression

BACKGROUND

Growing evidence suggests that cancer stem cells (CSCs) are responsible for cancer initiation in tumors. Bach1 has been identified to contribute to several tumor progression, including lung cancer. The role of Bach1 in CSCs remains poorly known. Therefore, the function of Bach1 on lung CSCs was focused currently.

METHODS

The expression of Bach1, CD133, CD44, Sox2, Nanog and Oct4 mRNA was assessed using Real-Time Quantitative Reverse Transcription PCR (RT-qPCR). Protein expression of Bach1, CD133, CD44, Sox2, Nanog, Oct4, p53, BCL2, BAX, p-p38, p-AKT1, c-Fos and c-Jun protein was analyzed by western blotting. 5-ethynyl-29-deoxyuridine (EdU), colony formation, Flow cytometry analysis and transwell invasion assay were carried out to analyze lung cancer cell proliferation, apoptosis and invasion respectively. Tumor sphere formation assay was utilized to evaluate spheroid capacity. Flow cytometry analysis was carried out to isolate CD133 or CD44 positive lung cancer cells. The relationship between Bach1 and CD44 was verified using ChIP-qPCR and dual-luciferase reporter assay. Xenograft tumor tissues were collected for hematoxylin and eosin (HE) staining and IHC analysis to evaluate histology and Ki-67.

RESULTS

The ratio of CD44 + CSCs from A549 and SPC-A1 cells were significantly enriched. Tumor growth of CD44 + CSCs was obviously suppressed in vivo compared to CD44- CSCs. Bach1 expression was obviously increased in CD44 + CSCs. Then, via using the in vitro experiment, it was observed that CSCs proliferation and invasion were greatly reduced by the down-regulation of Bach1 while cell apoptosis was triggered by knockdown of Bach1. Loss of Bach1 was able to repress tumor-sphere formation and tumor-initiating CSC markers. A repression of CSCs growth and metastasis of shRNA-Bach1 was confirmed using xenograft models and caudal vein injection. The direct interaction between Bach1 and CD44 was confirmed by ChIP-qPCR and dual-luciferase reporter assay. Furthermore, mitogen-activated protein kinases (MAPK) signaling pathway was selected and we proved the effects of Bach1 on lung CSCs were associated with the activation of the MAPK pathway. As manifested, loss of Bach1 was able to repress p-p38, p-AKT1, c-Fos, c-Jun protein levels in lung CSCs. Inhibition of MAPK signaling remarkably restrained lung CSCs growth and CSCs properties induced by Bach1 overexpression.

CONCLUSION

In summary, we imply that Bach1 demonstrates great potential for the treatment of lung cancer metastasis and recurrence via activating CD44 and MPAK signaling.

Chronic and Cycling Hypoxia: Drivers of Cancer Chronic Inflammation through HIF-1 and NF-κB Activation: A Review of the Molecular Mechanisms

Chronic (continuous, non-interrupted) hypoxia and cycling (intermittent, transient) hypoxia are two types of hypoxia occurring in malignant tumors. They are both associated with the activation of hypoxia-inducible factor-1 (HIF-1) and nuclear factor κB (NF-κB), which induce changes in gene expression. This paper discusses in detail the mechanisms of activation of these two transcription factors in chronic and cycling hypoxia and the crosstalk between both signaling pathways. In particular, it focuses on the importance of reactive oxygen species (ROS), reactive nitrogen species (RNS) together with nitric oxide synthase, acetylation of HIF-1, and the action of MAPK cascades. The paper also discusses the importance of hypoxia in the formation of chronic low-grade inflammation in cancerous tumors. Finally, we discuss the effects of cycling hypoxia on the tumor microenvironment, in particular on the expression of VEGF-A, CCL2/MCP-1, CXCL1/GRO-α, CXCL8/IL-8, and COX-2 together with PGE₂. These factors induce angiogenesis and recruit various cells into the tumor niche, including neutrophils and monocytes which, in the tumor, are transformed into tumor-associated neutrophils (TAN) and tumor-associated macrophages (TAM) that participate in tumorigenesis.

Hypoxia in Cancer and Fibrosis: Part of the Problem and Part of the Solution

Adaptive responses to hypoxia are involved in the progression of lung cancer and pulmonary fibrosis. However, it has not been pointed out that hypoxia may be the link between these diseases. As tumors or scars expand, a lack of oxygen results in the activation of the hypoxia response, promoting cell survival even during chronic conditions. The role of hypoxia-inducible factors (HIFs) as master regulators of this adaptation is crucial in both lung cancer and idiopathic pulmonary fibrosis, which have shown the active transcriptional signature of this pathway. Emerging evidence suggests that interconnected feedback loops such as metabolic changes, fibroblast differentiation or extracellular matrix remodeling contribute to HIF overactivation, making it an irreversible phenomenon. This review will focus on the role of HIF signaling and its possible overlapping in order to identify new opportunities in therapy and regeneration.