Early Events in the Molecular Pathogenesis of Lung Cancer

Premalignant Progression in the Lung: Knowledge Gaps and Novel Opportunities for Interception of Non-Small Cell Lung Cancer. An Official American Thoracic Society Research Statement

Rationale: Despite significant advances in precision treatments and immunotherapy, lung cancer is the most common cause of cancer death worldwide. To reduce incidence and improve survival rates, a deeper understanding of lung premalignancy and the multistep process of tumorigenesis is essential, allowing timely and effective intervention before cancer development. Objectives: To summarize existing information, identify knowledge gaps, formulate research questions, prioritize potential research topics, and propose strategies for future investigations into the premalignant progression in the lung. Methods: An international multidisciplinary team of basic, translational, and clinical scientists reviewed available data to develop and refine research questions pertaining to the transformation of premalignant lung lesions to advanced lung cancer. Results: This research statement identifies significant gaps in knowledge and proposes potential research questions aimed at expanding our understanding of the mechanisms underlying the progression of premalignant lung lesions to lung cancer in an effort to explore potential innovative modalities to intercept lung cancer at its nascent stages. Conclusions: The identified gaps in knowledge about the biological mechanisms of premalignant progression in the lung, together with ongoing challenges in screening, detection, and early intervention, highlight the critical need to prioritize research in this domain. Such focused investigations are essential to devise effective preventive strategies that may ultimately decrease lung cancer incidence and improve patient outcomes.

Mesoporous silica nanoparticles: a versatile carrier platform in lung cancer management

Mesoporous silica nanoparticles (MSNPs) are inorganic nanoparticles that have been comprehensively investigated and are intended to deliver therapeutic agents. MSNPs have revolutionized the therapy for various conditions, especially cancer and infectious diseases. In this article, the viability of MSNPs' administration for lung cancer therapy has been reviewed. However, certain challenges lay ahead in the successful translation such as toxicology, immunology, large-scale production, and regulatory matters have made it extremely difficult to translate such discoveries from the bench to the bedside. This review highlights recent developments, characteristics, mechanism of action and customization for targeted delivery. This review also covers the most recent data that sheds light on MSNPs' extraordinary therapeutic potential in fighting lung cancer as well as future hurdles.

An atlas of epithelial cell states and plasticity in lung adenocarcinoma

Understanding the cellular processes that underlie early lung adenocarcinoma (LUAD) development is needed to devise intervention strategies1. Here we studied 246,102 single epithelial cells from 16 early-stage LUADs and 47 matched normal lung samples. Epithelial cells comprised diverse normal and cancer cell states, and diversity among cancer cells was strongly linked to LUAD-specific oncogenic drivers. KRAS mutant cancer cells showed distinct transcriptional features, reduced differentiation and low levels of aneuploidy. Non-malignant areas surrounding human LUAD samples were enriched with alveolar intermediate cells that displayed elevated KRT8 expression (termed KRT8+ alveolar intermediate cells (KACs) here), reduced differentiation, increased plasticity and driver KRAS mutations. Expression profiles of KACs were enriched in lung precancer cells and in LUAD cells and signified poor survival. In mice exposed to tobacco carcinogen, KACs emerged before lung tumours and persisted for months after cessation of carcinogen exposure. Moreover, they acquired Kras mutations and conveyed sensitivity to targeted KRAS inhibition in KAC-enriched organoids derived from alveolar type 2 (AT2) cells. Last, lineage-labelling of AT2 cells or KRT8+ cells following carcinogen exposure showed that KACs are possible intermediates in AT2-to-tumour cell transformation. This study provides new insights into epithelial cell states at the root of LUAD development, and such states could harbour potential targets for prevention or intervention.

Ganodermanontriol Suppresses the Progression of Lung Adenocarcinoma by Activating CES2 to Enhance the Metabolism of Mycophenolate Mofetil

New anti-lung cancer therapies are urgently required to improve clinical outcomes. Since ganodermanontriol (GDNT) has been identified as a potential antineoplastic agent, its role in lung adenocarcinoma (LUAD) is investigated in this study. Concretely, lung cancer cells were treated with GDNT and/or mycophenolate mofetil (MMF), after which MTT assay, flow cytometry and Western blot were conducted. Following bioinformatics analysis, carboxylesterase 2 (CES2) was knocked down and rescue assays were carried out in vitro. Xenograft experiment was performed on mice, followed by drug administration, measurement of tumor growth and determination of CES2, IMPDH1 and IMPDH2 expressions. As a result, the viability of lung cancer cells was reduced by GDNT or MMF. GDNT enhanced the effects of MMF on suppressing viability, promoting apoptosis and inducing cell cycle arrest in lung cancer cells. GDNT up-regulated CES2 level, and strengthened the effects of MMF on down-regulating IMPDH1 and IMPDH2 levels in the cells. IMPDH1 and IMPDH2 were highly expressed in LUAD samples. CES2 was a potential target for GDNT. CES2 knockdown reversed the synergistic effect of GDNT and MMF against lung cancer in vitro. GDNT potentiated the role of MMF in inhibiting tumor growth and expressions of CES2 and IMPDH1/2 in lung cancer in vivo. Collectively, GDNT suppresses the progression of LUAD by activating CES2 to enhance the metabolism of MMF.

DNA methylome analysis reveals potential alterations contributing to the progression of bronchial hyperplasia

BACKGROUND

Squamous cell lung cancer (SCLC) arises from bronchial changes: basal cell hyperplasia (BCH), squamous metaplasia (SM), and dysplasia. However, the premalignant process preceding SCLC is not inevitable; it can stop at any of the bronchial lesions. Previously, we hypothesized that combinations of premalignant lesions observed in the small bronchi of SCLC patients can reflect the different "scenarios" of the premalignant process: BCHi-the stoppage at the stage of hyperplasia and BCHSM-the progression of hyperplasia to metaplasia.

METHODS AND RESULTS

In this study, using whole-genome bisulfite sequencing we analyzed the DNA methylome of two forms of BCH: isolated BCH (BCHi) and BCH co-occurred with SM (BCHSM) in the small bronchi of SCLC patients. It was shown that BCHi harbored differentially methylated regions (DMRs) affecting genes associated with regulating phosphatase activity. In BCHSM, DMRs were found in genes involved in PI3K-Akt and AMPK signaling pathways. DMRs were also found to affect specific miRNA genes: miR-34a and miR-3648 in BCHi and miR-924 and miR-100 in BCHSM.

CONCLUSIONS

Thus, this study demonstrated the significant changes in DNA methylome between the isolated BCH and BCH combined with SM. The identified epigenetic alterations may underlie different "scenarios" of the premalignant process in the bronchial epithelium.

Targeting Cell Signaling Pathways in Lung Cancer by Bioactive Phytocompounds

Lung cancer is a heterogeneous group of malignancies with high incidence worldwide. It is the most frequently occurring cancer in men and the second most common in women. Due to its frequent diagnosis and variable response to treatment, lung cancer was reported as the top cause of cancer-related deaths worldwide in 2020. Many aberrant signaling cascades are implicated in the pathogenesis of lung cancer, including those involved in apoptosis (B cell lymphoma protein, Bcl-2-associated X protein, first apoptosis signal ligand), growth inhibition (tumor suppressor protein or gene and serine/threonine kinase 11), and growth promotion (epidermal growth factor receptor/proto-oncogenes/phosphatidylinositol-3 kinase). Accordingly, these pathways and their signaling molecules have become promising targets for chemopreventive and chemotherapeutic agents. Recent research provides compelling evidence for the use of plant-based compounds, known collectively as phytochemicals, as anticancer agents. This review discusses major contributing signaling pathways involved in the pathophysiology of lung cancer, as well as currently available treatments and prospective drug candidates. The anticancer potential of naturally occurring bioactive compounds in the context of lung cancer is also discussed, with critical analysis of their mechanistic actions presented by preclinical and clinical studies.

Metabolomic, DNA Methylomic, and Transcriptomic Profiling of Suberoylanilide Hydroxamic Acid Effects on LPS-Exposed Lung Epithelial Cells

Suberoylanilide hydroxamic acid (SAHA) is a histone deacetylase (HDAC) inhibitor with anticancer effects via epigenetic and non-epigenetic mechanisms. The role of SAHA in metabolic rewiring and epigenomic reprogramming to inhibit pro-tumorigenic cascades in lung cancer remains unknown. In this study, we aimed to investigate the regulation of mitochondrial metabolism, DNA methylome reprogramming, and transcriptomic gene expression by SAHA in lipopolysaccharide (LPS)-induced inflammatory model of lung epithelial BEAS-2B cells. LC/MS was used for metabolomic analysis, while next-generation sequencing was done to study epigenetic changes. The metabolomic study reveals that SAHA treatment significantly regulated methionine, glutathione, and nicotinamide metabolism with alteration of the metabolite levels of methionine, S-adenosylmethionine, S-adenosylhomocysteine, glutathione, nicotinamide, 1-methylnicotinamide, and nicotinamide adenine dinucleotide in BEAS-2B cells. Epigenomic CpG methyl-seq shows SAHA revoked a list of differentially methylated regions in the promoter region of the genes, such as HDAC11, miR4509-1, and miR3191. Transcriptomic RNA sequencing (RNA-seq) reveals SAHA abrogated LPS-induced differentially expressed genes encoding proinflammatory cytokines, including interleukin 1α (IL1α), IL1β, IL2, IL6, IL24, and IL32. Integrative analysis of DNA methylome-RNA transcriptome displays a list of genes, of which CpG methylation correlated with changes in gene expression. qPCR validation of transcriptomic RNA-seq data shows that SAHA treatment significantly reduced the LPS-induced mRNA levels of IL1β, IL6, DNA methyltransferase 1 (DNMT1), and DNMT3A in BEAS-2B cells. Altogether, SAHA treatment alters the mitochondrial metabolism, epigenetic CpG methylation, and transcriptomic gene expression to inhibit LPS-induced inflammatory responses in lung epithelial cells, which may provide novel molecular targets to inhibit the inflammation component of lung carcinogenesis.

PREVENTION RELEVANCE

Inflammation increases the risk of lung cancer and blocking inflammation could reduce the incidence of lung cancer. Herein, we demonstrate that histone deacetylase inhibitor suberoylanilide hydroxamic acid regulates metabolic rewiring and epigenetic reprogramming to attenuate lipopolysaccharide-driven inflammation in lung epithelial cells.

Interrogating the precancerous evolution of pathway dysfunction in lung squamous cell carcinoma using XTABLE

Lung squamous cell carcinoma (LUSC) is a type of lung cancer with a dismal prognosis that lacks adequate therapies and actionable targets. This disease is characterized by a sequence of low- and high-grade preinvasive stages with increasing probability of malignant progression. Increasing our knowledge about the biology of these premalignant lesions (PMLs) is necessary to design new methods of early detection and prevention, and to identify the molecular processes that are key for malignant progression. To facilitate this research, we have designed XTABLE (Exploring Transcriptomes of Bronchial Lesions), an open-source application that integrates the most extensive transcriptomic databases of PMLs published so far. With this tool, users can stratify samples using multiple parameters and interrogate PML biology in multiple manners, such as two- and multiple-group comparisons, interrogation of genes of interests, and transcriptional signatures. Using XTABLE, we have carried out a comparative study of the potential role of chromosomal instability scores as biomarkers of PML progression and mapped the onset of the most relevant LUSC pathways to the sequence of LUSC developmental stages. XTABLE will critically facilitate new research for the identification of early detection biomarkers and acquire a better understanding of the LUSC precancerous stages.

The Single-Cell Immunogenomic Landscape of B and Plasma Cells in Early-Stage Lung Adenocarcinoma

Tumor-infiltrating B and plasma cells (TIB) are prevalent in lung adenocarcinoma (LUAD); however, they are poorly characterized. We performed paired single-cell RNA and B-cell receptor (BCR) sequencing of 16 early-stage LUADs and 47 matching multiregion normal tissues. By integrative analysis of ∼50,000 TIBs, we define 12 TIB subsets in the LUAD and adjacent normal ecosystems and demonstrate extensive remodeling of TIBs in LUADs. Memory B cells and plasma cells (PC) were highly enriched in tumor tissues with more differentiated states and increased frequencies of somatic hypermutation. Smokers exhibited markedly elevated PCs and PCs with distinct differentiation trajectories. BCR clonotype diversity increased but clonality decreased in LUADs, smokers, and with increasing pathologic stage. TIBs were mostly localized within CXCL13+ lymphoid aggregates, and immune cell sources of CXCL13 production evolved with LUAD progression and included elevated fractions of CD4 regulatory T cells. This study provides a spatial landscape of TIBs in early-stage LUAD.

SIGNIFICANCE

While TIBs are highly enriched in LUADs, they are poorly characterized. This study provides a much-needed understanding of the transcriptional, clonotypic states and phenotypes of TIBs, unraveling their potential roles in the immunopathology of early-stage LUADs and constituting a road map for the development of TIB-targeted immunotherapies for the treatment of this morbid malignancy. This article is highlighted in the In This Issue feature, p. 2483.

IL-17A Promotes the Migration, Invasion and the EMT Process of Lung Cancer Accompanied by NLRP3 Activation

Background

Lung cancer is a deadly cancer worldwide, and its pathogenesis and treatment methods require continuous research and exploration. As a representative factor of adaptive immunity, the role of interleukin-17A (IL-17A) in lung cancer is still unclear. The purpose of the present study was to investigate the effect of IL-17A on the biological behaviour of lung cancer cells and the relative mechanism.

Methods

The human lung adenocarcinoma A549 and H1299 cell lines were used for in vitro study. The effects of IL-17A on cell proliferation, migration and invasion were assessed by CCK-8 assay, wound-healing assay, transwell invasion assay and real-time cell analysis (RTCA). The expression levels of marker proteins in the process of epithelial-mesenchymal transition (EMT) were detected by western blot analysis. Caspase-1 activity and the concentration of IL-1β after NLRP3 inflammasome activation were measured by a Caspase-1 Activity Assay Kit and an IL-1β ELISA kit, respectively.

Results

Compared to the control group, IL-17A treatment did not affect the proliferation of A549 and H1299 cells in vitro, but it promoted cell migration, invasion and the EMT process. IL-17A treatment increased NLRP3 expression, caspase-1 activity and IL-1β level. Blockade of NLRP3 alleviated the cell migration, invasion and the EMT process induced by IL-17A.

Conclusions

In conclusion, these findings indicated that NLRP3 participates in the migration, invasion and the EMT process of IL-17A-stimulated lung cells in vitro.

Cell-by-Cell: Unlocking Lung Cancer Pathogenesis

For lung cancers, cellular trajectories and fates are strongly pruned by cell intrinsic and extrinsic factors. Over the past couple of decades, the combination of comprehensive molecular and genomic approaches, as well as the use of relevant pre-clinical models, enhanced micro-dissection techniques, profiling of rare preneoplastic lesions and surrounding tissues, as well as multi-region tumor sequencing, have all provided in-depth insights into the early biology and evolution of lung cancers. The advent of single-cell sequencing technologies has revolutionized our ability to interrogate these same models, tissues, and cohorts at an unprecedented resolution. Single-cell tracking of lung cancer pathogenesis is now transforming our understanding of the roles and consequences of epithelial-microenvironmental cues and crosstalk during disease evolution. By focusing on non-small lung cancers, specifically lung adenocarcinoma subtype, this review aims to summarize our knowledge base of tumor cells-of-origin and tumor-immune dynamics that have been primarily fueled by single-cell analysis of lung adenocarcinoma specimens at various stages of disease pathogenesis and of relevant animal models. The review will provide an overview of how recent reports are rewriting the mechanistic details of lineage plasticity and intra-tumor heterogeneity at a magnified scale thanks to single-cell studies of early- to late-stage lung adenocarcinomas. Future advances in single-cell technologies, coupled with analysis of minute amounts of rare clinical tissues and novel animal models, are anticipated to help transform our understanding of how diverse micro-events elicit macro-scale consequences, and thus to significantly advance how basic genomic and molecular knowledge of lung cancer evolution can be translated into successful targets for early detection and prevention of this lethal disease.

Chronic Exposure to Waterpipe Smoke Elicits Immunomodulatory and Carcinogenic Effects in the Lung

Effects of waterpipe smoking on lung pathobiology and carcinogenesis remain sparse despite the worldwide emergence of this tobacco vector. To address this gap, we investigated the effects of chronic waterpipe smoke (WPS) exposure on lung pathobiology, host immunity, and tumorigenesis using an experimental animal model that is prone to tobacco carcinogens and an exploratory observational analysis of human waterpipe smokers and nonsmokers. Mice exhibited elevated incidence of lung tumors following heavy WPS exposure (5 days/week for 20 weeks) compared to littermates with light WPS (once/week for 20 weeks) or control air. Lungs of mice exposed to heavy WPS showed augmented CD8+ and CD4+ T cell counts along with elevated protumor immune phenotypes including increased IL17A in T/B cells, PD-L1 on tumor and immune cells, and the proinflammatory cytokine IL1β in myeloid cells. RNA-sequencing (RNA-seq) analysis showed reduced antitumor immune gene signatures in animals exposed to heavy WPS relative to control air. We also performed RNA-seq analysis of airway epithelia from bronchial brushings of cancer-free waterpipe smokers and nonsmokers undergoing diagnostic bronchoscopy. Transcriptomes of normal airway cells in waterpipe smokers, relative to waterpipe nonsmokers, harbored gene programs that were associated with poor clinical outcomes in patients with lung adenocarcinoma, alluding to a WPS-associated molecular injury, like that established in response to cigarette smoking. Our findings support the notion that WPS exhibits carcinogenic effects and constitutes a possible risk factor for lung cancer as well as warrant future studies that can guide evidence-based policies for mitigating waterpipe smoking.

PREVENTION RELEVANCE

Potential carcinogenic effects of waterpipe smoking are very poorly understood despite its emergence as a socially acceptable form of smoking. Our work highlights carcinogenic effects of waterpipe smoking in the lung and, thus, accentuate the need for inclusion of individuals with exclusive waterpipe smoking in prevention and smoking cessation studies.

Role of Long Noncoding RNAs in Smoking-Induced Lung Cancer: An In Silico Study

The prevalence of lung cancer induced by cigarette smoking has increased over time. Long noncoding (lnc) RNAs, regulatory factors that play a role in human diseases, are commonly dysregulated in lung cancer. Cigarette smoking is closely related to changes in lncRNA expression, which can affect lung cancer. Herein, we assess the mechanism of lung cancer initiation induced by smoking. To calculate the impact of smoking on the survival of patients with lung cancer, we extracted data from The Cancer Genome Atlas and Gene Expression Omnibus databases and identified the differentially expressed genes in the lung cancer tissue compared to the normal lung tissue. Genes positively and negatively associated with smoking were identified. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and Cytoscape analyses were performed to determine the function of the genes and the effects of smoking on the immune microenvironment. lncRNAs corresponding to smoking-associated genes were identified, and a smoking-related lncRNA model was constructed using univariate and multivariate Cox analyses. This model was used to assess the survival of and potential risk in patients who smoked. During screening, 562 differentially expressed genes were identified, and we elucidated that smoking affected the survival of patients 4.5 years after the diagnosis of lung cancer. Furthermore, genes negatively associated with smoking were closely associated with immunity. Twelve immune cell types were also found to infiltrate differentially in smokers and nonsmokers. Thus, the smoking-associated lncRNA model is a good predictor of survival and risk in smokers and may be used as an independent prognostic factor for lung cancer.

ZNF143 Expression is Associated with COPD and Tumor Microenvironment in Non-Small Cell Lung Cancer

Background

Chronic obstructive pulmonary disease (COPD) is an inflammatory-related disease highly associated with increased lung cancer risk. Studies have explored the tumor promoting roles for zinc finger protein 143 (ZNF143). However, the role of ZNF143 in COPD and tumor microenvironment of non-small cell lung cancer (NSCLC) has not been fully elucidated.

Methods

COPD-related key genes were identified by differential gene expression evaluation, WGCNA and SVM-RFE analysis using mRNA expression data retrieved from public databases. ROC analysis was conducted to evaluate the diagnostic value of ZNF143. Correlation between ZNF143 and clinic-pathological features, associations with tumor-infiltrating immune cells (TICs) and the relationship with predictors of immunotherapy efficacy were explored. ZNF143 gene expression was validated by qRT-PCR using an independent cohort.

Results

Bioinformatic and machine learning analysis showed that ZNF143 was a COPD-related gene. ZNF143 expression was significantly upregulated in COPD and is a potential diagnostic biomarker in COPD with AUC > 0.85. ZNF143 expression was significantly upregulated in lung squamous cell carcinoma (LUSC) and lung adenocarcinoma (LUAD). ZNF143 expression levels were significantly higher in LUAD patients with COPD relative to the levels in patients only with LUAD. Upregulation of ZNF143 in patients with comorbidity of NSCLC and COPD was further confirmed by qRT-PCR analysis. High expression of ZNF143 was significantly correlated with advanced TNM stage in LUSC. High ZNF143 expression was associated with activated TICs in both LUAD and LUSC samples. Moreover, ZNF143 expression was significantly correlated with the levels of several known predictors of immunotherapy efficacy, including PD-L1, PD-L2, TMB and TIDE in NSCLC.

Conclusion

ZNF143 is a novel COPD biomarker. High expression level of ZNF143 is associated with immune microenvironment and high risk of progression of COPD to NSCLC.

Lung cancer: Premalignant biology and medical prevention

Lung cancer (both adenocarcinoma and squamous cell) progress through a series of pre-malignant histologic changes before the development of invasive disease. Each of these carcinogenic cascades is defined by genetic and epigenetic alterations in pulmonary epithelial cells. Additionally, alterations in the immune response, progenitor cell function, mutational burden, and microenvironmental mediated survival of mutated clones contribute to the risk of pre-malignant lesions progressing to cancer. Medical preventions studies have been completed and current and future trials are informed by the improved understanding of pre-malignancy. This will lead to precision chemoprevention trials based on lesional biology and histologic characteristics.

Causal associations between dietary antioxidant vitamin intake and lung cancer: A Mendelian randomization study

Background

Oxidative stress is currently considered to be closely related to the occurrence of respiratory tumors, especially lung cancer. Many observational studies have shown that increased antioxidant intake can reduce the risk of lung cancer, but the results are still controversial. Therefore, we performed a two-sample Mendelian randomized (MR) analysis to clarify the causal relationship between antioxidant vitamins and lung cancer.

Methods

To assess the causal effect of dietary antioxidant vitamin intake on lung cancer, we conducted a two-sample MR analysis and we extracted single-nucleotide polymorphisms (SNPs) that are associated with antioxidants from genome-wide association studies (GWASs) of the UK biobank. We gathered summary data for lung cancer from the International Lung Cancer Consortium (ILCCO), including 11,348 cases and 15,861 controls, and applied the inverse-variance weighted (IVW) method as the primary MR analysis, and performed a sensitivity analysis to verify the results.

Results

The results showed that higher dietary retinol intake was causally associated with lung cancer overall [odds ratio (OR) = 1.844, 95% CI, 1.359-2.502, p = 0.00009], squamous cell lung cancer (OR = 2.162, 95% CI, 1.117-4.183, p = 0.022), and lung adenocarcinoma (OR = 1.706, 95% CI, 1.084-2.685, p = 0.021). Additionally, carotene was positively correlated with lung adenocarcinoma (OR = 1.510, 95% CI, 1.002-2.276, p = 0.049). However, there was a non-significant relationship between the intake of other dietary antioxidants (vitamin C and vitamin E) and lung cancer.

Conclusion

Our research showed that dietary retinol intake has an adverse impact on lung cancer, and carotene might increase the risk of adenocarcinoma. This highlights the importance of revealing the underlying mechanisms of dietary antioxidant vitamins in lung cancer and delivers an important health message that dietary antioxidant vitamin intake may not be necessary for the prevention of lung cancer. It also provides a basis for future research.

Lymphocyte cytosolic protein 2 is a novel prognostic marker in lung adenocarcinoma

OBJECTIVE

Lymphocyte cytosolic protein 2 (LCP2) is often ectopically expressed in various human tumors. However, the clinical significance and role of LCP2 in lung adenocarcinoma (LUAD) remain unclear. This study explored the prognostic significance of LCP2 in LUAD patients.

METHODS

LCP2 expression in LUAD tissues was analyzed using data from The Cancer Genome Atlas and Genotype-Tissue Expression databases. Western blotting was employed to detect LCP2 expression in LUAD. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to explore signaling pathways mediated by LCP2 co-regulatory genes. Immunohistochemistry was used to examine levels of LCP2 and programmed death ligand 1 (PD-L1) in 68 LUAD patients. Associations between LCP2 expression and clinicopathological features, prognoses, and PD-L1 levels among the LUAD in-patients were analyzed.

RESULTS

Among the 68 LUAD in-patients, LCP2 expression was correlated with clinical stage and lymph node metastasis. LUAD patients with high LCP2 expression were associated with increased overall survival. LCP2 expression may be associated with an enrichment of several immune functions. Moreover, our immunohistochemistry results demonstrated that LCP2 expression was positively correlated with PD-L1 expression in LUAD tissues.

CONCLUSIONS

In the study, LCP2 was found to be a favorable prognostic biomarker in LUAD patients.

Core genes involved in the regulation of acute lung injury and their association with COVID-19 and tumor progression: A bioinformatics and experimental study

Acute lung injury (ALI) is a specific form of lung damage caused by different infectious and non-infectious agents, including SARS-CoV-2, leading to severe respiratory and systemic inflammation. To gain deeper insight into the molecular mechanisms behind ALI and to identify core elements of the regulatory network associated with this pathology, key genes involved in the regulation of the acute lung inflammatory response (Il6, Ccl2, Cat, Serpine1, Eln, Timp1, Ptx3, Socs3) were revealed using comprehensive bioinformatics analysis of whole-genome microarray datasets, functional annotation of differentially expressed genes (DEGs), reconstruction of protein-protein interaction networks and text mining. The bioinformatics data were validated using a murine model of LPS-induced ALI; changes in the gene expression patterns were assessed during ALI progression and prevention by anti-inflammatory therapy with dexamethasone and the semisynthetic triterpenoid soloxolone methyl (SM), two agents with different mechanisms of action. Analysis showed that 7 of 8 revealed ALI-related genes were susceptible to LPS challenge (up-regulation: Il6, Ccl2, Cat, Serpine1, Eln, Timp1, Socs3; down-regulation: Cat) and their expression was reversed by the pre-treatment of mice with both anti-inflammatory agents. Furthermore, ALI-associated nodal genes were analysed with respect to SARS-CoV-2 infection and lung cancers. The overlap with DEGs identified in postmortem lung tissues from COVID-19 patients revealed genes (Saa1, Rsad2, Ifi44, Rtp4, Mmp8) that (a) showed a high degree centrality in the COVID-19-related regulatory network, (b) were up-regulated in murine lungs after LPS administration, and (c) were susceptible to anti-inflammatory therapy. Analysis of ALI-associated key genes using The Cancer Genome Atlas showed their correlation with poor survival in patients with lung neoplasias (Ptx3, Timp1, Serpine1, Plaur). Taken together, a number of key genes playing a core function in the regulation of lung inflammation were found, which can serve both as promising therapeutic targets and molecular markers to control lung ailments, including COVID-19-associated ALI.

The Challenge of Long-Term Cultivation of Human Precision-Cut Lung Slices

Human precision-cut lung slices (PCLS) have proven to be an invaluable tool for numerous toxicologic, pharmacologic, and immunologic studies. Although a cultivation period of <1 week is sufficient for most studies, modeling of complex disease mechanisms and investigating effects of long-term exposure to certain substances require cultivation periods that are much longer. So far, data regarding tissue integrity of long-term cultivated PCLS are incomplete. More than 1500 human PCLS from 16 different donors were cultivated under standardized, serum-free conditions for up to 28 days and the viability, tissue integrity, and the transcriptome was assessed in great detail. Even though viability of PCLS was well preserved during long-term cultivation, a continuous loss of cells was observed. Although the bronchial epithelium was well preserved throughout cultivation, the alveolar integrity was preserved for about 2 weeks, and the vasculatory system experienced significant loss of integrity within the first week. Furthermore, ciliary beat in the small airways gradually decreased after 1 week. Interestingly, keratinizing squamous metaplasia of the alveolar epithelium with significantly increasing manifestation were found over time. Transcriptome analysis revealed a significantly increased immune response and significantly decreased metabolic activity within the first 24 hours after PCLS generation. Overall, this study provides a comprehensive overview of histomorphologic and pathologic changes during long-term cultivation of PCLS.

Sophoraflavanone G Resensitizes ABCG2-Overexpressing Multidrug-Resistant Non-Small-Cell Lung Cancer Cells to Chemotherapeutic Drugs

Elevated expression of the ATP-binding cassette (ABC) drug transporter ABCG2 in cancer cells contributes to the development of the multidrug resistance phenotype in patients with advanced non-small-cell lung cancer (NSCLC). Due to the lack of U.S. Food and Drug Administration (FDA)-approved synthetic inhibitors of ABCG2, significant efforts have been invested in discovering bioactive compounds of plant origin that are capable of reversing ABCG2-mediated multidrug resistance in cancer cells. Sophoraflavanone G (SFG), a phytoncide isolated from the plant species Sophora flavescens, is known to possess a wide spectrum of pharmacological activities, including antibacterial, anti-inflammatory, antimalarial, and antiproliferative effects. In the present study, the chemosensitizing effect of SFG in ABCG2-overexpressing NSCLC cells was investigated. Experimental results demonstrate that at subtoxic concentrations SFG significantly reversed ABCG2-mediated multidrug resistance in a concentration-dependent manner. Additional biochemical data and in silico docking analysis of SFG to the inward-open conformation of human ABCG2 indicate that SFG inhibited the drug transport function of ABCG2 by interacting with residues within the transmembrane substrate-binding pocket of ABCG2. Collectively, these findings provide evidence that SFG has the potential to be further tested as an effective inhibitor of ABCG2 to improve the efficacy of therapeutic drugs in patients with advanced NSCLC.

Early Diagnosis and Screening for Lung Cancer

Cancer interception refers to actively blocking the cancer development process by preventing progression of premalignancy to invasive disease. The rate-limiting steps for effective lung cancer interception are the incomplete understanding of the earliest molecular events associated with lung carcinogenesis, the lack of preclinical models of pulmonary premalignancy, and the challenge of developing highly sensitive and specific methods for early detection. Recent advances in cancer interception are facilitated by developments in next-generation sequencing, computational methodologies, as well as the renewed emphasis in precision medicine and immuno-oncology. This review summarizes the current state of knowledge in the areas of molecular abnormalities in lung cancer continuum, preclinical human models of lung cancer pathogenesis, and the advances in early lung cancer diagnostics.

Evaluation of the Radiomics Method for the Prediction of Atypical Adenomatous Hyperplasia in Patients With Subcentimeter Pulmonary Ground-Glass Nodules

Objectives

We aimed to develop a prediction model to distinguish atypical adenomatous hyperplasia (AAH) from early lung adenocarcinomas in patients with subcentimeter pulmonary ground-glass nodules (GGNs), which may help avoid aggressive surgical resection for patients with AAH.

Methods

Surgically confirmed cases of AAH and lung adenocarcinomas manifesting as GGNs of less than 1 cm were retrospectively collected. A prediction model based on radiomics and clinical features identified from a training set of cases was built to differentiate AAH from lung adenocarcinomas and tested on a validation set.

Results

Four hundred and eighty-five eligible cases were included and randomly assigned to the training (n = 339) or the validation sets (n = 146). The developed radiomics prediction model showed good discrimination performance to distinguish AAH from adenocarcinomas in both the training and the validation sets, with, respectively, 84.1% and 82.2% of accuracy, and AUCs of 0.899 (95% CI: 0.867–0.931) and 0.881 (95% CI: 0.827–0.936).

Conclusion

The prediction model based on radiomics and clinical features can help differentiate AAH from adenocarcinomas manifesting as subcentimeter GGNs and may prevent aggressive resection for AAH patients, while reserving this treatment for adenocarcinomas.

Oncogenic potential of human pluripotent stem cell-derived lung organoids with HER2 overexpression

Lung adenocarcinoma (LUAD) is the most common types among lung cancers generally arising from terminal airway and understanding of multistep carcinogenesis is crucial to develop novel therapeutic strategy for LUAD. Here we used human induced pluripotent stem cells (hiPSCs) to establish iHER2-hiPSCs in which doxycycline induced the expression of the oncoprotein human epidermal growth factor receptor 2 (HER2)/ERBB2. Lung progenitors that differentiated from iHER2-hiPSCs, which expressed NKX2-1/TTF-1 known as a lung lineage maker, were cocultured with human fetal fibroblast and formed human lung organoids (HLOs) comprising alveolar type 2-like cells. HLOs that overexpressed HER2 transformed to tumor-like structures similar to atypical adenomatous hyperplasia, which is known for lung precancerous lesion and upregulated the activities of oncogenic signaling cascades such as RAS/RAF/MAPK and PI3K/AKT/mTOR. The degree of morphological irregularity and proliferation capacity were significantly higher in HLOs from iHER2-hiPSCs. Moreover, the transcriptome profile of the HLOs shifted from a normal lung tissue-like state to one characteristic of clinical LUAD with HER2 amplification. Our results suggest that hiPSC-derived HLOs may serve as a model to recapitulate the early tumorigenesis of LUAD and would provide new insights into the molecular basis of tumor initiation and progression.

Clinical value of 3'-deoxy-3'-[18F]fluorothymidine-positron emission tomography for diagnosis, staging and assessing therapy response in lung cancer

Lung cancer has the highest mortality rate of any tumour type. The main driver of lung tumour growth and development is uncontrolled cellular proliferation. Poor patient outcomes are partly the result of the limited range of effective anti-cancer therapies available and partly due to the limited accuracy of biomarkers to report on cell proliferation rates in patients. Accordingly, accurate methods of diagnosing, staging and assessing response to therapy are crucial to improve patient outcomes. One effective way of assessing cell proliferation is to employ non-invasive evaluation using 3'-deoxy-3'-[¹⁸F]fluorothymidine ([¹⁸F]FLT) positron emission tomography [¹⁸F]FLT-PET. [¹⁸F]FLT, unlike the most commonly used PET tracer [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG), can specifically report on cell proliferation and does not accumulate in inflammatory cells. Therefore, this radiotracer could exhibit higher specificity in diagnosis and staging, along with more accurate monitoring of therapy response at early stages in the treatment cycle. This review summarises and evaluates published studies on the clinical use of [¹⁸F]FLT to diagnose, stage and assess response to therapy in lung cancer.

Long non-coding RNA SLC25A25-AS1 exhibits oncogenic roles in non-small cell lung cancer by regulating the microRNA-195-5p/ITGA2 axis

Long non-coding RNA SLC25A25 antisense RNA 1 (SLC25A25-AS1) exerts antitumour activity in colorectal cancer. The present study investigated whether SLC25A25-AS1 is implicated in the aggressiveness of non-small cell lung cancer (NSCLC) and the possible underlying mechanism. SLC25A25-AS1 expression in NSCLC was determined by reverse transcription-quantitative PCR. The proliferation, apoptosis, migration and invasion of NSCLC cells were tested in vitro through cell counting kit-8 assay, flow cytometry analysis, Transwell migration and invasion assays, followed by in vivo validation using animal experiments. Additionally, the competitive endogenous RNA theory for SLC25A25-AS1, microRNA-195-5p (miR-195-5p) and integrin α2 (ITGA2) was identified using subcellular fractionation, bioinformatics analysis, reverse transcription-quantitative PCR, western blotting, a luciferase assay and RNA immunoprecipitation. As compared with normal lung tissues, increased expression of SLC25A25-AS1 was demonstrated in NSCLC tissues using The Cancer Genome Atlas database.. In addition, SLC25A25-AS1 was overexpressed in both NSCLC tissues and cell lines. High SLC25A25-AS1 expression was markedly associated with shorter overall survival time of patients with NSCLC. SLC25A25-AS1 silencing impeded NSCLC cell proliferation and triggered apoptosis, while restricting cell migration and invasion. Tumour growth in vivo was also impaired by SLC25A25-AS1 silencing. Mechanistically, SLC25A25-AS1 was demonstrated to be an miR-195-5p sponge in NSCLC cells. miR-195-5p mimics decreased ITGA2 expression in NSCLC cells by directly targeting ITGA2, and SLC25A25-AS1 interference decreased ITGA2 expression by sequestering miR-195-5p. Furthermore, the antitumour effects of SLC25A25-AS1 silencing on malignant behaviours were counteracted when ITGA2 was restored or when miR-195-5p was silenced. In summary, by controlling the miR-195-5p/ITGA2 axis, SLC25A25-AS1 served tumour-promoting roles in NSCLC cells. Therefore, the SLC25A25-AS1/miR-195-5p/ITGA2 signalling pathway might be an attractive target for future therapeutic options in NSCLC.

Pathology and Classification of SCLC

Simple Summary

Small cell lung carcinoma (SCLC), is a high-grade neuroendocrine carcinoma defined by its aggressiveness, poor differentiation, and somber prognosis. This review highlights current pathological concepts including classification, immunohistochemistry features, and differential diagnosis. Additionally, we summarize the current knowledge of the immune tumor microenvironment, tumor heterogeneity, and genetic variations of SCLC. Recent comprehensive genomic research has improved our understanding of the diverse biological processes that occur in this tumor type, suggesting that a new era of molecular-driven treatment decisions is finally foreseeable for SCLC patients.

Abstract

Lung cancer is consistently the leading cause of cancer-related death worldwide, and it ranks as the second most frequent type of new cancer cases diagnosed in the United States, both in males and females. One subtype of lung cancer, small cell lung carcinoma (SCLC), is an aggressive, poorly differentiated, and high-grade neuroendocrine carcinoma that accounts for 13% of all lung carcinomas. SCLC is the most frequent neuroendocrine lung tumor, and it is commonly presented as an advanced stage disease in heavy smokers. Due to its clinical presentation, it is typically diagnosed in small biopsies or cytology specimens, with routine immunostaining only. However, immunohistochemistry markers are extremely valuable in demonstrating neuroendocrine features of SCLC and supporting its differential diagnosis. The 2015 WHO classification grouped all pulmonary neuroendocrine carcinomas in one category and maintained the SCLC combined variant that was previously recognized. In this review, we explore multiple aspects of the pathologic features of this entity, as well as clinically relevant immunohistochemistry markers expression and its molecular characteristics. In addition, we will focus on characteristics of the tumor microenvironment, and the latest pathogenesis findings to better understand the new therapeutic options in the current era of personalized therapy.

Evolution of DNA methylome from precancerous lesions to invasive lung adenocarcinomas

The evolution of DNA methylome and methylation intra-tumor heterogeneity (ITH) during early carcinogenesis of lung adenocarcinoma has not been systematically studied. We perform reduced representation bisulfite sequencing of invasive lung adenocarcinoma and its precursors, atypical adenomatous hyperplasia, adenocarcinoma in situ and minimally invasive adenocarcinoma. We observe gradual increase of methylation aberrations and significantly higher level of methylation ITH in later-stage lesions. The phylogenetic patterns inferred from methylation aberrations resemble those based on somatic mutations suggesting parallel methylation and genetic evolution. De-convolution reveal higher ratio of T regulatory cells (Tregs) versus CD8 + T cells in later-stage diseases, implying progressive immunosuppression with neoplastic progression. Furthermore, increased global hypomethylation is associated with higher mutation burden, copy number variation burden and AI burden as well as higher Treg/CD8 ratio, highlighting the potential impact of methylation on chromosomal instability, mutagenesis and tumor immune microenvironment during early carcinogenesis of lung adenocarcinomas.

Augmented Lipocalin-2 Is Associated with Chronic Obstructive Pulmonary Disease and Counteracts Lung Adenocarcinoma Development

Rationale: Early pathogenesis of lung adenocarcinoma (LUAD) remains largely unknown. We found that, relative to wild-type littermates, the innate immunomodulator Lcn2 (lipocalin-2) was increased in normal airways from mice with knockout of the airway lineage gene Gprc5a (Gprc5a^-/-) and that are prone to developing inflammation and LUAD. Yet, the role of LCN2 in lung inflammation and LUAD is poorly understood.Objectives: Delineate the role of Lcn2 induction in LUAD pathogenesis.Methods: Normal airway brushings, uninvolved lung tissues, and tumors from Gprc5a^-/- mice before and after tobacco carcinogen exposure were analyzed by RNA sequencing. LCN2 mRNA was analyzed in public and in-house data sets of LUAD, lung squamous cancer (LUSC), chronic obstructive pulmonary disease (COPD), and LUAD/LUSC with COPD. LCN2 protein was immunohistochemically analyzed in a tissue microarray of 510 tumors. Temporal lung tumor development, gene expression programs, and host immune responses were compared between Gprc5a^-/- and Gprc5a^-/-/Lcn2^-/- littermates.Measurements and Main Results: Lcn2 was progressively elevated during LUAD development and positively correlated with proinflammatory cytokines and inflammation gene sets. LCN2 was distinctively elevated in human LUADs, but not in LUSCs, relative to normal lungs and was associated with COPD among smokers and patients with LUAD. Relative to Gprc5a^-/- mice, Gprc5a^-/-/Lcn2^-/- littermates exhibited significantly increased lung tumor development concomitant with reduced T-cell abundance (CD4⁺) and richness, attenuated antitumor immune gene programs, and increased immune cell expression of protumor inflammatory cytokines.Conclusions: Augmented LCN2 expression is a molecular feature of COPD-associated LUAD and counteracts LUAD development in vivo by maintaining antitumor immunity.

Systemic Inflammatory Markers of Survival in Epidermal Growth Factor-Mutated Non-Small-Cell Lung Cancer: Single-Institution Analysis, Systematic Review, and Meta-analysis

BACKGROUND

Systemic inflammatory response (SIR) may influence prognosis in epidermal growth factor receptor (EGFR)-mutated (m) non-small-cell lung cancer (NSCLC). Pretreatment SIR markers (neutrophil-to-lymphocyte ratio [NLR], platelet-to-lymphocyte ratio, lymphocyte-to-monocyte ratio [LMR], lactate dehydrogenase [LDH], and lung immune prognostic index [LIPI]) were assessed as prognostic factors in NSCLC survival.

PATIENTS AND METHODS

Retrospective survival analysis (overall survival [OS] and progression-free survival [PFS]) of EGFR-mutated NSCLC patients at Princess Margaret Cancer Centre were performed separately for early (I-IIIa) and late (IIIb-IV) stage disease for individual SIR variables, dichotomized by optimal cutoff points by Kaplan-Meier survival analysis and multivariable Cox proportional hazard modeling. A systematic review and meta-analysis of known SIR studies in patients with late-stage EGFR-mutated were also performed.

RESULTS

From 2012 to 2019, in 530 patients, significant adjusted hazard ratios (aHR) for OS comparing high versus low NLR were 2.12 for early stage and 1.79 for late stage disease. Additionally, late stage cohorts had significant associations, as follows: high versus low derived NLR, aHR = 1.53; LMR, aHR = 0.62; LDH, aHR = 2.04; and LIPI, aHR = 2.04. Similar patterns were found for PFS in early stage NLR (aHR = 1.96) and late stage NLR (aHR = 1.46), while for PFS, only late stage derived NLR (aHR = 1.34), LDH (aHR = 1.75), and LIPI (aHR = 1.66) were significant. A meta-analysis confirmed that NLR, LMR, LDH, and LIPI were all significantly associated with OS and PFS in the late stage.

CONCLUSION

This primary study and meta-analysis demonstrated that LMR and LDH were significantly associated with late stage EGFR-mutated NSCLC outcomes, and the LIPI scoring system was prognostic. NLR remained an independent prognostic factor across all stages and could represent an early marker of immuno-oncology interactions.

LncRNA SNHG10 is downregulated in non-small cell lung cancer and predicts poor survival

BACKGROUND

LncRNA SNHG10 has been reported to be an oncogenic lncRNA in liver cancer. However, its roles in non-small cell lung cancer (NSCLC) remains unknown.

METHODS

Tumor and paired non-tumor tissues were harvested from 62 NSCLC patients. RT-qPCR was used to detect the expression of SNHG10 and miR-21 in tissues. Overexpression experiments were used to evaluate the interaction between SNHG10 and miR-21 in NSCLC cells. CCK-8 assay was used to detect the cell proliferation.

RESULTS

We observed the expression of SNHG10 was down-regulated in non-small cell lung cancer (NSCLC) compared with that in non-tumor tissues. Moreover, we found that high expression levels of SNHG10 predicted favorable survival of NSCLC patients, and the expression of miR-21 were increased in NSCLC and inversely correlated with SNHG10 expression. In NSCLC cells, overexpression of SNHG10 resulted in increased miR-21 gene methylation and decreased miR-21 expression. Moreover, overexpression of SNHG10 attenuated the enhancing effect of miR-21 overexpression on cell proliferation.

CONCLUSIONS

SNHG10 may involve in NSCLC cell proliferation by regulating the miR-21 gene methylation.

LncRNA SNHG9 is Downregulated in Non-Small Cell Lung Cancer and Suppressed miR-21 Through Methylation to Promote Cell Proliferation

Background

LncRNA SNHG9 has been shown to be an oncogenic lncRNA in glioblastoma, while its role in other cancers is unknown. The aim of this study was to investigate the role of SNHG9 in non-small cell lung cancer (NSCLC).

Methods

The differential expression of SNHG9 in NSCLC was first explored by analyzing the TCGA dataset, followed by measuring the expression levels of SNHG9 in paired NSCLC and non-tumor tissues by RT-qPCR. Expression of miR-21 was also determined by RT-qPCR. Correlations were analyzed by linear regression. The interaction between miR-21 and SNHG9 was detected using RNA pull-down. The expression relationship between SNHG9 and miR-21 was analyzed by SNHG9 or miR-21 overexpression experiments. The effects of overexpression of SNHG9 on the methylation of miR-21 were analyzed by methylation-specific PCR (MSP). Cell proliferation was evaluated by CCK-8 assay.

Results

By analyzing the TCGA dataset, we observed downregulation of SNHG9 in NSCLC, which was confirmed by measuring the expression levels of SNHG9 in paired NSCLC tumor tissues and non-tumor tissues from NSCLC patients involved in this study. MiR-21 was upregulated in NSCLC tumor tissues and inversely correlated with SNHG9 in cancer tissues but not in non-tumor tissues. The interaction between SNHG9 and miR-21 was predicted by bioinformatic analyses, which was further verified by RNA pull-down. In NSCLC cells, overexpression of SNHG9 led to downregulated miR-21 and increased methylation of miR-21 gene. In contrast, miR-21 did not affect the expression of SNHG9. In addition, overexpression of SNHG9 attenuated the enhancing effects of miR-21 on NSCLC proliferation.

Conclusion

SNHG9 might downregulate miR-21 through methylation to suppress cancer cell proliferation.

Long noncoding RNA NR2F1-AS1 promotes the malignancy of non-small cell lung cancer via sponging microRNA-493-5p and thereby increasing ITGB1 expression

Several studies have reported that the long noncoding ribonucleic acid (lncRNA) NR2F1 antisense RNA 1 (NR2F1-AS1) affects multiple cellular pathways that are involved in tumorigenesis and tumor progression. The present study aimed to detect NR2F1-AS1 expression in non-small cell lung cancer (NSCLC), investigate the role of NR2F1-AS1 in promoting the tumorigenic behavior of NSCLC cells, and elucidate the mechanism underlying the effect of NR2F1-AS1 on NSCLC progression. Our results showed that NR2F1-AS1 expression was upregulated in NSCLC cells, and notably, its upregulation was correlated with adverse clinical characteristics and shorter overall survival in patients with NSCLC. The absence of NR2F1-AS1 functionally decreased NSCLC cell proliferation, migration, and invasion and promoted tumor cell apoptosis. In addition, the tumor growth of NSCLC cells in vivo was inhibited after NR2F1-AS1 silencing. Mechanistically, NR2F1-AS1 functioned as a competing endogenous RNA for miR-493-5p and consequently increased ITGB1 expression. Rescue assays further validated that an increased output of the miR-493-5p/ITGB1 axis could neutralize the regulatory impact of NR2F1-AS1 knockdown on the malignant phenotype of NSCLC cells. In summary, the NR2F1-AS1/miR-493-5p/ITGB1 pathway initiates pro-oncogenic behavior in NSCLC tumor progression, and the NR2F1-AS1/miR-493-5p/ITGB1 axis may provide new molecular targets for anticancer therapy against NSCLC.

Neoadjuvant chemotherapy combined with intraoperative radiotherapy is effective to prevent recurrence in high-risk non-small cell lung cancer (NSCLC) patients

Background

Basal cell hyperplasia (BCH) and squamous metaplasia (SM) in the small bronchi distant from the tumor is associated with a high risk of non-small cell lung cancer (NSCLC) recurrence. Here, we assessed whether neoadjuvant chemotherapy (NAC), intraoperative radiotherapy (IORT), or adjuvant chemotherapy (AC) is effective to prevent recurrence in NSCLC patients (n=171) with different premalignant lesions in the small bronchi

Methods

BCH, SM, and dysplasia (D) were identified in the samples of lung tissue distant from the tumor. NSCLC patients were treated by surgery, different combinations of NAC and IORT, and AC.

Results

Based on the type of bronchial lesions, NSCLC patients were classified into four groups: BCH⁺SM⁻D⁻ (55.6%, 95/171), BCH⁺SM⁺D⁻ (26.3%; 45/171), BCH⁻SM⁺D⁺ (6.4%, 11/171), and BCH⁻SM⁻D⁻ (11.7%, 20/171). During 5 years, recurrent carcinoma was found in 13.4% (23/171) of patients and represented by metachronous metastases in the thoracic lymph nodes (82.6%, 19/23) and by a relapse in the bronchial stump (17.4%, 4/23). Recurrence was frequent in BCH⁺SM⁺D⁻ patients (87.0%, 20/23), rare in BCH⁺SM⁻D⁻ and BCH⁻SM⁻D⁻ patients (13.0%, 3/23), and absent in BCH⁻SM⁺D⁺ patients (0/23). The 5-year recurrence-free survival was also shorter in BCH⁺SM⁺D⁻ patients (HR 27.35; 95% CI: 6.31−118.48; P<0.0001). In the high-risk (BCH⁺SM⁺D⁻) group, recurrence occurred mainly in cases without NAC and IORT (88.2%, 15/17) and was absent (0/15) when these therapies were combined. NAC- and IORT-negative patients also showed poor overall survival (HR 4.35; 95% CI: 1.96−9.66; P<0.0001) and tended to have decreased recurrence-free survival (P=0.075). Importantly, the recurrence rate was not different between AC-treated and AC-naïve BCH⁺SM⁺D⁻ patients.

Conclusions

The combination of NAC and IORT is an effective strategy to prevent recurrence in high-risk NSCLC patients.

Genetic Markers in Lung Cancer Diagnosis: A Review

Lung cancer is the most often diagnosed cancer in the world and the most frequent cause of cancer death. The prognosis for lung cancer is relatively poor and 75% of patients are diagnosed at its advanced stage. The currently used diagnostic tools are not sensitive enough and do not enable diagnosis at the early stage of the disease. Therefore, searching for new methods of early and accurate diagnosis of lung cancer is crucial for its effective treatment. Lung cancer is the result of multistage carcinogenesis with gradually increasing genetic and epigenetic changes. Screening for the characteristic genetic markers could enable the diagnosis of lung cancer at its early stage. The aim of this review was the summarization of both the preclinical and clinical approaches in the genetic diagnostics of lung cancer. The advancement of molecular strategies and analytic platforms makes it possible to analyze the genome changes leading to cancer development-i.e., the potential biomarkers of lung cancer. In the reviewed studies, the diagnostic values of microsatellite changes, DNA hypermethylation, and p53 and KRAS gene mutations, as well as microRNAs expression, have been analyzed as potential genetic markers. It seems that microRNAs and their expression profiles have the greatest diagnostic potential value in lung cancer diagnosis, but their quantification requires standardization.

Long noncoding RNA OSER1‑AS1 promotes the malignant properties of non‑small cell lung cancer by sponging microRNA‑433‑3p and thereby increasing Smad2 expression

OSER1 antisense RNA 1 (OSER1-AS1), a long noncoding RNA, has been well studied in the context of hepatocellular carcinoma. However, its expression status, specific functions, and tumorigenic mechanism in non-small cell lung cancer (NSCLC) remain uninvestigated. Hence, this study aimed to assess OSER1-AS1 expression, test the malignancy-related biological functions of OSER1-AS1, and illustrate how they affect NSCLC progression. OSER1-AS1 expression in NSCLC was measured by reverse transcription-quantitative polymerase chain reaction. Cell Counting Kit-8 assay, flow cytometry, cell migration and invasion assay, and tumor xenograft assay were performed to analyze the effects of OSER1-AS1 on the malignant phenotypes of NSCLC cells. Bioinformatics prediction with luciferase reporter and RNA immunoprecipitation assays were performed to determine the interaction between OSER1-AS1 and microRNA-433-3p (miR-433-3p). OSER1-AS1 was strongly expressed in NSCLC tissues and cell lines. Enhanced OSER1-AS1 expression was significantly correlated with tumor size, TNM stage, and lymph node metastasis in patients with NSCLC. Patients with NSCLC exhibiting high OSER1-AS1 expression had shorter overall survival than those exhibiting low OSER1-AS1 expression. Functionally, a reduction in OSER1-AS1 expression led to significant decreases in NSCLC cell proliferation, migration, and invasion as well as an increase in cell apoptosis in vivo. OSER1-AS1 knockdown suppressed the tumorigenic ability of NSCLC cells in vivo. Mechanistically, OSER1-AS1 acts as a competing endogenous RNA (ceRNA) in NSCLC cells by sponging miR-433-3p and thereby increasing the expression of mothers against decapentaplegic homolog 2 (Smad2). Finally, restoration experiments revealed that the suppression of miR-433-3p and restoration of Smad2 both counteracted the suppressive effects of OSER1-AS1 depletion in NSCLC cells. Our findings illustrate the biological importance of the OSER1-AS1/miR-433-3p/Smad2 pathway in NSCLC progression and offer a novel perspective regarding the identification of effective therapeutic and diagnostic targets.

lncRNA LEF1-AS1 Promotes Proliferation and Induces Apoptosis of Non-Small-Cell Lung Cancer Cells by Regulating miR-221/PTEN Signaling

Introduction

LEF1-AS1 is a characterized oncogenic lncRNA in oral cancer. Analysis of TCGA dataset revealed the upregulation of LEF1-AS1 in non-small-cell lung cancer (NSCLC). This study was therefore carried out to investigate the involvement of LEF1-AS1 in NSCLC.

Methods

A total of 62 NSCLC patients were included to collect paired cancer and non-tumor tissues. RT-qPCR was performed to measure levels of LEF1-AS1 and miR-221 expression. Transient transfections were performed to explore the interactions between LEF1-AS1, miR-221 and PTEN. Cell proliferation and apoptosis were analyzed by cell proliferation assay and cell apoptosis assay, respectively.

Results

We found that LEF1-AS1 was upregulated in NSCLC patients. In addition, expression of LEF1-AS1 was negatively correlated with the expression of PTEN but positively correlated with the expression of miR-221 in NSCLC tissue samples. In NSCLC cells, overexpression of LEF1-AS1 led to downregulated expression of PTEN but upregulated expression of miR-221, which can directly target PTEN. Overexpression of LEF1-AS1 and miR-221 promoted cancer cell proliferation and inhibited apoptosis. PTEN played an opposite role and reduced the effects of overexpressing LEF1-AS1 and miR-221.

Conclusion

LEF1-AS1 may promote the proliferation and induce apoptosis of NSCLC cells by regulating miR-221/PTEN signaling.

Rationale for Lung Adenocarcinoma Prevention and Drug Development Based on Molecular Biology During Carcinogenesis

Lung adenocarcinoma (LUAD) is the most common and aggressive subtype of lung cancer with the greatest heterogeneity and aggression. Inspite of recent years’ achievements in understanding the pathogenesis of this disease, as well as the development of new therapeutic approaches, our knowledge on crucial early molecular events during its development is still rudimentary. Recent classification and grading of LUAD has postulated that LUAD does not arise spontaneously, but through a stepwise process from lung adenomatous premalignancy atypical adenomatous hyperplasia to adenocarcinoma in situ, minimally invasive adenocarcinoma, and eventually frankly invasive predominant adenocarcinoma. In this review, we discuss the molecular processes that drive the evolutionary process that results in the formation of LUAD. We also describe how to handle lung premalignancy in clinical settings based on the most recent advances in genomic biology and our own understanding of lung cancer prevention.

Restoration of Mal overcomes the defects of apoptosis in lung cancer cells

BACKGROUND AND AIMS

Cancer is one of the life-threatening diseases of human beings; the pathogenesis of cancer remains to be further investigated. Toll like receptor (TLR) activities are involved in the apoptosis regulation. This study aims to elucidate the role of Mal (MyD88-adapter-like) molecule in the apoptosis regulation of lung cancer (LC) cells.

METHODS

The LC tissues were collected from LC patients. LC cells and normal control (NC) cells were isolated from the tissues and analyzed by pertinent biochemical and immunological approaches.

RESULTS

We found that fewer apoptotic LC cells were induced by cisplatin in the culture as compared to NC cells. The expression of Fas ligand (FasL) was lower in LC cells than that in NC cells. FasL mRNA levels declined spontaneously in LC cells. A complex of FasL/TDP-43 was detected in LC cells. LC cells expressed less Mal than NC cells. Activation of Mal by lipopolysaccharide (LPS) increased TDP-43 expression in LC cells. TDP-43 formed a complex with FasL mRNA to prevent FasL mRNA from decay. Reconstitution of Mal or TDP-43 restored the sensitiveness of LC cells to apoptotic inducers.

CONCLUSIONS

LC cells express low Mal levels that contributes to FasL mRNA decay through impairing TDP-43 expression. Reconstitution of Mal restores sensitiveness of LC cells to apoptosis inducers that may be a novel therapeutic approach for LC treatment.

A Novel Flavonoid Kushenol Z from Sophora flavescens Mediates mTOR Pathway by Inhibiting Phosphodiesterase and Akt Activity to Induce Apoptosis in Non-Small-Cell Lung Cancer Cells

The roots of Sophora flavescens (SF) are clinically used as a traditional Chinese medicine for the treatment of various lung diseases. In this study, we investigated the mechanism by which SF inhibits proliferation and induces apoptosis in non-small-cell lung cancer (NSCLC) cells. A new compound, kushenol Z (KZ), and 14 known flavonoids were isolated from SF. KZ, sophoraflavanone G, and kushenol A demonstrated potent cytotoxicity against NSCLC cells in a dose- and time-dependent manner; KZ showed a wide therapeutic window. We also found that KZ induced NSCLC cell apoptosis by increasing the Bax/Bcl-2 ratio and by activating caspase-3 and caspase-9 leading to mitochondrial apoptosis, and upregulated CHOP and activatedcaspase-7 and caspase-12, which triggered the endoplasmic reticulum stress pathway. After KZ treatment, we observed cAMP accumulation, which reflected the inhibition of cAMP-phosphodiesterase (PDE), along with the increase in PKA activity; additionally, phospho-p70 S6 kinase was downregulated. KZ also attenuated the phosphorylation of Akt and PRAS40, which was partially rescued by an Akt activator. This suggested that KZ mediated the antiproliferative activity in NSCLC cells by inhibiting the mTOR pathway through the inhibition of cAMP-PDE and Akt. These findings suggested that KZ may be used as a promising cAMP-PDE and Akt inhibitor in targeted chemotherapeutic drug development.

Long-term cancer risk associated with lung nodules observed on low-dose screening CT scans

OBJECTIVE

Non-calcified nodules (NCNs) associated with false positive low-dose CT (LDCT) lung cancer screens have been attributed to various causes. Some, however, may represent lung cancer precursors. An association of NCNs with long-term lung cancer risk would provide indirect evidence of some NCNs being cancer precursors.

METHODS

LDCT arm participants in the National Lung Screening Trial (NLST) received LDCT screens at baseline and years 1-2. The relationship between NCNs found on LDCT screens and subsequent lung cancer diagnosis over different time periods was examined at the person and lobe level. For the latter, a lobe had a cancer outcome only if the cancer was located in the lobe. Separate analyses were performed on baseline and post-baseline LDCT findings; for the latter, those with baseline NCNs were excluded and only new (non-pre-existing) NCNs examined. Raw and adjusted rate-ratios (RRs) were computed for presence of NCNs and subsequent lung cancer risk; adjusted RRs controlled for demographic and smoking factors.

RESULTS

26,309 participants received the baseline LDCT screen. Over median 11.3 years follow-up, 1675 lung cancers were diagnosed. Adjusted RRs for time periods 0-4, 4-8 and 8-12 years following the baseline screen were 5.1 (95 % CI:4.4-5.9), 1.5 (95 % CI:1.3-1.9) and 1.5 (95 % CI:1.2-1.8) at the person-level and 14.7 (95 % CI:12.6-17.2), 2.6 (95 % CI: 2.0-3.4) and 2.2 (95 % CI:1.6-2.9) at the lobe-level. 18,585 participants were included in the post-baseline analysis. Adjusted RRs for periods 0-4, 4-8 and 8-11 years were 5.6 (95 % CI: 4.5-7.0), 1.9 (95 % CI: 1.3-2.7) and 1.6 (95 % CI: 0.9-2.9) at the person-level and 19.6 (95 % CI:14.9-25.3), 2.5 (95 % CI:1.3-4.7) and 3.3 (95 % CI:1.4-7.6) at the lobe-level. Raw RRs were similar.

CONCLUSION

NCNs are associated with excess long-term lung cancer risk, suggesting that some may be lung cancer precursors.

Epithelial cell plasticity defines heterogeneity in lung cancer

Lung cancer is the leading cause of cancer death for both men and women and accounts for almost 18.4% of all deaths due to cancer worldwide, with the global incidence increasing by approximately 0.5% per year. Lung cancer is regarded as a devastating type of cancer owing to its high prevalence, reduction in the health-related quality of life, frequently delayed diagnosis, low response rate, high toxicity, and resistance to available therapeutic options. The highly heterogeneous nature of this cancer with a proximal-to-distal distribution throughout the respiratory tract dramatically affects its diagnostic and therapeutic management. The diverse composition and plasticity of lung epithelial cells across the respiratory tract are regarded as significant factors underlying lung cancer heterogeneity. Therefore, definitions of the cells of origin for different types of lung cancer are urgently needed to understand lung cancer biology and to achieve early diagnosis and develop cell-targeted therapies. In the present review, we will discuss the current understanding of the cellular and molecular alterations in distinct lung epithelial cells that result in each type of lung cancer.

Microwave Ablation in Primary Lung Malignancies

Lung cancer is the leading cause of cancer-related mortality worldwide. Eighty-five percent of cases correspond to non-small cell lung cancer (NSCLC) and pivotal nonsurgical options for early-stage disease include percutaneous ablation and stereotactic body radiation therapy (SBRT). Microwave Ablation (MWA) is a locoregional treatment option that has many advantages over radiofrequency ablation and has been able to overcome the limitations of this technique in the treatment of early-stage NSCLC. In this review article, we highlight the current evidence supporting the use of MWA in patients with early-stage NSCLC and discuss the technical considerations of the procedure, including optimal patient selection and planning strategies, as well as the potential complications and reported outcomes. Finally, we mention future trends involving ablation in NSCLC, including its role in combination with SBRT in central tumors, management of post-SBRT local recurrence, and its potential as an adjuvant treatment option for patients with resistance to systemic therapy or in combination with checkpoint inhibitors.

Driver Mutations in Normal Airway Epithelium Elucidate Spatiotemporal Resolution of Lung Cancer

Rationale: Uninvolved normal-appearing airway epithelium has been shown to exhibit specific mutations characteristic of nearby non-small cell lung cancers (NSCLCs). Yet, its somatic mutational landscape in patients with early-stage NSCLC is unknown.Objectives: To comprehensively survey the somatic mutational architecture of the normal airway epithelium in patients with early-stage NSCLC.Methods: Multiregion normal airways, comprising tumor-adjacent small airways, tumor-distant large airways, nasal epithelium and uninvolved normal lung (collectively airway field), matched NSCLCs, and blood cells (n = 498) from 48 patients were interrogated for somatic single-nucleotide variants by deep-targeted DNA sequencing and for chromosomal allelic imbalance events by genome-wide genotype array profiling. Spatiotemporal relationships between the airway field and NSCLCs were assessed by phylogenetic analysis.Measurements and Main Results: Genomic airway field carcinogenesis was observed in 25 cases (52%). The airway field epithelium exhibited a total of 269 somatic mutations in most patients (n = 36) including key drivers that were shared with the NSCLCs. Allele frequencies of these acquired variants were overall higher in NSCLCs. Integrative analysis of single-nucleotide variants and allelic imbalance events revealed driver genes with shared "two-hit" alterations in the airway field (e.g., TP53, KRAS, KEAP1, STK11, and CDKN2A) and those with single hits progressing to two in the NSCLCs (e.g., PIK3CA and NOTCH1).Conclusions: Tumor-adjacent and tumor-distant normal-appearing airway epithelia exhibit somatic driver alterations that undergo selection-driven clonal expansion in NSCLC. These events offer spatiotemporal insights into the development of NSCLC and, thus, potential targets for early treatment.

Exhaled breath condensate biomarkers for lung cancer

Lung cancer is the main cause of cancer incidence and mortality worldwide and the identification of clinically useful biomarkers for lung cancer detection at both early and metastatic stage is a pressing medical need. Although many improvements have been made in the treatment and in the early screening of this cancer, most diagnosis are made at a late stage, when a lot of genetic and epigenetic changes have occurred. A promising source of biomarkers reflective of the pathogenesis of lung cancer is exhaled breath condensate (EBC), a biological fluid and a natural matrix of the respiratory tract. Molecules such as DNAs, RNAs, proteins, metabolites and volatile compounds are present in EBC, and their presence/absence or their variation in concentrations can be used as biomarkers. The aims of this review are to briefly describe exhaled breath composition, firstly, and then to document some of the EBC candidate biomarkers for lung cancer by dividing them according to their origin (genome, transcriptome, epigenome, metabolome, proteome and microbiota) in order to demonstrate the potential use of EBC as a helpful tool in cancer diagnostics, molecular profiling, therapy monitoring and screening of high risk individuals.

Carcinogen-induced tumors in SFN-transgenic mice harbor a characteristic mutation spectrum of human lung adenocarcinoma

The landscape of genetic alterations in disease models such as transgenic mice or mice with carcinogen‐induced tumors has provided a huge amount of information that has shed light on the process of tumorigenesis in human non‐small‐cell lung cancer (NSCLC). We have previously identified stratifin (SFN) as a potent oncogene, and generated SFN‐transgenic (Tg‐SPC‐SFN^+/−) mice, which express human SFN (hSFN) only in the lung. Here, we have found that carcinogen nicotine‐derived nitrosaminoketone (NNK)‐induced tumors developing in Tg‐SPC‐SFN^+/− mice show a similar histology to human lung adenocarcinoma and exhibit high hSFN expression. In order to compare the genetic characteristics of Tg‐SPC‐SFN^+/− tumors and human lung adenocarcinoma, the former were subjected to whole‐exome sequencing. Interestingly, Tg‐SPC‐SFN^+/− tumors showed the distinct distribution of exonic mutations and high number of mutated genes and transversion. Moreover, Tg‐SPC‐SFN^+/− tumors showed 73 genes that were commonly detected in more than 2 tumors, mutations of which were also found in human lung adenocarcinoma. The expression levels of some of these genes were significantly associated with the clinical outcome of lung adenocarcinoma patients. Additionally, mutated genes in Tg‐SPC‐SFN^+/− tumors were closely associated with key canonical pathways such as PI3K/AKT signaling and apoptosis signaling. These results suggest that SFN overexpression is a universal abnormality in human lung adenocarcinogenesis and Tg‐SPC‐SFN^+/− tumors recapitulate key features of major human lung adenocarcinoma. Therefore, Tg‐SPC‐SFN^+/− mice provide a useful model for clarifying the molecular mechanism underlying lung adenocarcinogenesis.

Premalignant lesions of squamous cell carcinoma of the lung: The molecular make-up and factors affecting their progression

Squamous cell carcinoma (SCC), one of the most common forms of lung cancer, shows accelerated progression and aggressive growth and usually is observed at advanced stages. SCC originates from morphological changes in the bronchial epithelium that occur during chronic inflammation: basal cell hyperplasia, squamous metaplasia, and dysplasia I-III. However, the process is not inevitable; it can be stopped at any stage, remain in the stable state indefinitely and either progress or regress. The reasons and mechanisms of different scenarios of the evolution of premalignant lesions in the respiratory epithelium are not fully understood. In this review, we summarized the literature data (including our own data) regarding genetic, epigenetic, transcriptomic and proteomic profiles of the premalignant lesions and highlighted factors (environmental causes, inflammation, and gene polymorphism) that may govern their progression or regression. In conclusion, we reviewed strategies for lung cancer prevention and proposed new models and research directions for studying premalignant lesions and developing new tools to predict the risk of their malignant transformation.

Germline Predisposition and Copy Number Alteration in Pre-stage Lung Adenocarcinomas Presenting as Ground-Glass Nodules

Objective: Synchronous multiple ground-glass nodules (SM-GGNs) are a distinct entity of lung cancer which has been emerging increasingly in recent years in China. The oncogenesis molecular mechanisms of SM-GGNs remain elusive. Methods: We investigated single nucleotide variations (SNV), insertions and deletions (INDEL), somatic copy number variations (CNV), and germline mutations of 69 SM-GGN samples collected from 31 patients, using target sequencing (TRS) and whole exome sequencing (WES). Results: In the entire cohort, many known driver mutations were found, including EGFR (21.7%), BRAF (14.5%), and KRAS (6%). However, only one out of the 31 patients had the same somatic missense or truncated events within SM-GGNs, indicating the independent origins for almost all of these SM-GGNs. Many germline mutations with a low frequency in the Chinese population, and genes harboring both germline and somatic variations, were discovered in these pre-stage GGNs. These GGNs also bore large segments of copy number gains and/or losses. The CNV segment number tended to be positively correlated with the germline mutations (r = 0.57). The CNV sizes were correlated with the somatic mutations (r = 0.55). A moderate correlation (r = 0.54) was also shown between the somatic and germline mutations. Conclusion: Our data suggests that the precancerous unstable CNVs with potentially predisposing genetic backgrounds may foster the onset of driver mutations and the development of independent SM-GGNs during the local stimulation of mutagens.

Genome-Wide and Phenotypic Evaluation of Stem Cell Progenitors Derived From Gprc5a-Deficient Murine Lung Adenocarcinoma With Somatic Kras Mutations

Lung adenocarcinomas (LUADs) with somatic mutations in the KRAS oncogene comprise the most common molecular subtype of lung cancer in smokers and present with overall dismal prognosis and resistance to most therapies. Our group recently demonstrated that tobacco carcinogen-exposed mice with knockout of the airway lineage G-protein coupled receptor, Gprc5a, develop LUADs with somatic mutations in Kras. Earlier work has suggested that cancer stem cells (CSCs) play crucial roles in clonal evolution of tumors and in therapy resistance. To date, our understanding of CSCs in LUADs with somatic Kras mutations remains lagging. Here we derived CSCs (as spheres in 3D cultures) with self-renewal properties from a murine Kras-mutant LUAD cell line we previously established from a tobacco carcinogen-exposed Gprc5a^−/− mouse. Using syngeneic Gprc5a^−/− models, we found that these CSCs, compared to their parental isoforms, exhibited increased tumorigenic potential in vivo, particularly in female animals. Using whole-transcriptome sequencing coupled with pathways analysis and confirmatory PCR, we identified gene features (n = 2,600) differentially expressed in the CSCs compared to parental cells and that were enriched with functional modules associated with an augmented malignant phenotype including stemness, tumor-promoting inflammation and anti-oxidant responses. Further, based on in silico predicted activation of GSK3β in CSCs, we found that tideglusib, an irreversible inhibitor of the kinase, exhibited marked anti-growth effects in the cultured CSCs. Our study underscores molecular cues in the pathogenesis of Kras-mutant LUAD and presents new models to study the evolution, and thus high-potential targets, of this aggressive malignancy.

Genomic landscape of allelic imbalance in premalignant atypical adenomatous hyperplasias of the lung

Background

Genomic investigation of atypical adenomatous hyperplasia (AAH), the only known precursor lesion to lung adenocarcinomas (LUAD), presents challenges due to the low mutant cell fractions. This necessitates sensitive methods for detection of chromosomal aberrations to better study the role of critical alterations in early lung cancer pathogenesis and the progression from AAH to LUAD.

Methods

We applied a sensitive haplotype-based statistical technique to detect chromosomal alterations leading to allelic imbalance (AI) from genotype array profiling of 48 matched normal lung parenchyma, AAH and tumor tissues from 16 stage-I LUAD patients. To gain insights into shared developmental trajectories among tissues, we performed phylogenetic analyses and integrated our results with point mutation data, highlighting significantly-mutated driver genes in LUAD pathogenesis.

Findings

AI was detected in nine AAHs (56%). Six cases exhibited recurrent loss of 17p. AI and the enrichment of 17p events were predominantly identified in patients with smoking history. Among the nine AAH tissues with detected AI, seven exhibited evidence for shared chromosomal aberrations with matched LUAD specimens, including losses harboring tumor suppressors on 17p, 8p, 9p, 9q, 19p, and gains encompassing oncogenes on 8q, 12p and 1q.

Interpretation

Chromosomal aberrations, particularly 17p loss, appear to play critical roles early in AAH pathogenesis. Genomic instability in AAH, as well as truncal chromosomal aberrations shared with LUAD, provide evidence for mutation accumulation and are suggestive of a cancerized field contributing to the clonal selection and expansion of these premalignant lesions.

Fund

Supported in part by Cancer Prevention and Research Institute of Texas (CPRIT) grant RP150079 (PS and HK), NIH grant R01HG005859 (PS) and The University of Texas MD Anderson Cancer Center Core Support Grant.

Epigenetic Suppression of the T-box Subfamily 2 (TBX2) in Human Non-Small Cell Lung Cancer

(1) The TBX2 subfamily of transcription factors (TBXs 2, 3, 4 and 5) are markedly down-regulated in human non-small cell lung cancer (NSCLC) and exert tumor suppressor effects in lung malignancy. Yet, mechanisms underlying suppressed expression of the TBX2 subfamily in NSCLC are elusive. Here, we interrogated probable epigenetic mechanisms in suppressed expression of the TBX2 subfamily in human NSCLC. (2) TBX2 subfamily gene expression and methylation levels in NSCLC and normal lung tissues were surveyed using publicly available RNA-sequence and genome-wide methylation datasets. Methylation β-values of the four genes were statistically compared between NSCLCs and normal lung tissues, correlated with gene expression levels, and interrogated with clinicopathological variables. Expression and methylation levels of TBXs were quantified in NSCLC cells using real-time PCR and methylation-specific PCR assays, respectively. Effects of the DNA methyltransferase inhibitor 5-azacytidine (Aza) on TBX2 subfamily expression were assessed in NSCLC cells. Impact of TBX2 subfamily expression on Aza-treated cells was evaluated by RNA interference. (3) All four TBXs were significantly hypermethylated in NSCLCs relative to normal lung tissues (p < 0.05). Methylation β-values of the genes, with exception of TBX2, were significantly inversely correlated with corresponding mRNA expression levels (p < 0.05). We found no statistically significant differences in hypermethylation levels of the TBX2 subfamily by clinicopathological features including stage and tobacco history. Expression levels of the TBX genes were overall suppressed in NSCLC cells relative to normal alveolar cells. Members of the subfamily were significantly hypermethylated in all tested NSCLC cell lines relative to normal alveolar cells. Treatment with Aza induced the expression of the TBX2 subfamily concomitant with NSCLC cell growth inhibition. Further, simultaneous knockdown of the four TBX genes markedly reduced anti-growth effects of Aza in NSCLC cells. (4) Our study sheds light on new epigenetic profiles in the molecular pathogenesis of human NSCLC.