Aggressive early-stage lung adenocarcinoma is characterized by epithelial cell plasticity with acquirement of stem-like traits and immune evasion phenotype.

Lung adenocarcinoma (LUAD) is the main non-small-cell lung cancer diagnosed in ~40-50% of all lung cancer cases. Despite the improvements in early detection and personalized medicine, even a sizable fraction of patients with early-stage LUAD would experience disease relapses and adverse prognosis. Previous reports indicated the existence of LUAD molecular subtypes characterized by specific gene expression and mutational profiles, and correlating with prognosis. However, the biological and molecular features of such subtypes have not been further explored. Consequently, the mechanisms driving the emergence of aggressive LUAD remained unclear. Here, we adopted a multi-tiered approach ranging from molecular to functional characterization of LUAD and used it on multiple cohorts of patients (for a total of 1227 patients) and LUAD cell lines. We investigated the tumor transcriptome and the mutational and immune gene expression profiles, and we used LUAD cell lines for cancer cell phenotypic screening. We found that loss of lung cell lineage and gain of stem cell-like characteristics, along with mutator and immune evasion phenotypes, explain the aggressive behavior of a specific subset of lung adenocarcinoma that we called C1-LUAD, including early-stage disease. This subset can be identified using a 10-gene prognostic signature. Poor prognosis patients appear to have this specific molecular lung adenocarcinoma subtype which is characterized by peculiar molecular and biological features. Our data support the hypothesis that transformed lung stem/progenitor cells and/or reprogrammed epithelial cells with CSC characteristics are hallmarks of this aggressive disease. Such discoveries suggest alternative, more aggressive, therapeutic strategies for early-stage C1-LUAD.

Essential role of smooth muscle Rac1 in severe asthma-associated airway remodelling.

BACKGROUND: Severe asthma is a chronic lung disease characterised by inflammation, airway hyperresponsiveness (AHR) and airway remodelling. The molecular mechanisms underlying uncontrolled airway smooth muscle cell (aSMC) proliferation involved in pulmonary remodelling are still largely unknown. Small G proteins of the Rho family (RhoA, Rac1 and Cdc42) are key regulators of smooth muscle functions and we recently demonstrated that Rac1 is activated in aSMC from allergic mice. The objective of this study was to assess the role of Rac1 in severe asthma-associated airway remodelling. METHODS AND RESULTS: Immunofluorescence analysis in human bronchial biopsies revealed an increased Rac1 activity in aSMC from patients with severe asthma compared with control subjects. Inhibition of Rac1 by EHT1864 showed that Rac1 signalling controlled human aSMC proliferation induced by mitogenic stimuli through the signal transducer and activator of transcription 3 (STAT3) signalling pathway. In vivo, specific deletion of Rac1 in SMC or pharmacological inhibition of Rac1 by nebulisation of NSC23766 prevented AHR and aSMC hyperplasia in a mouse model of severe asthma. Moreover, the Rac1 inhibitor prevented goblet cell hyperplasia and epithelial cell hypertrophy whereas treatment with corticosteroids had less effect. Nebulisation of NSC23766 also decreased eosinophil accumulation in the bronchoalveolar lavage of asthmatic mice. CONCLUSION: This study demonstrates that Rac1 is overactive in the airways of patients with severe asthma and is essential for aSMC proliferation. It also provides evidence that Rac1 is causally involved in AHR and airway remodelling. Rac1 may represent as an interesting target for treating both AHR and airway remodelling of patients with severe asthma.

Clinical and histopathologic predictors of therapeutic response to bronchial thermoplasty in severe refractory asthma.

BACKGROUND: Phenotypes and endotypes predicting optimal response to bronchial thermoplasty (BT) in patients with severe asthma remain elusive. OBJECTIVE: Our aim was to compare the clinical characteristics and hallmarks of airway inflammation and remodeling before and after BT in responder and partial responder patients with severe asthma refractory to oral steroids and to omalizumab. METHODS: In all, 23 patients with severe refractory asthma were divided into BT responders (n = 15) and BT partial responders (n = 8), according to the decrease in asthma exacerbations at 12 months after BT. Clinical parameters were compared at baseline and 12 months after BT, and hallmarks of airway inflammation and remodeling were analyzed by immunohistochemistry in bronchial biopsy specimens before and 3 months after BT. RESULTS: At baseline, the BT responders were around 8 years younger than the BT partial responders (P = .02) and they had a greater incidence of atopy, higher numbers of blood eosinophils (both P = .03) and IgE levels, higher epithelial IFN-α expression, and higher numbers of mucosal eosinophils and IL-33-positive cells (P ≤ .05). A reduction in blood eosinophil count, serum IgE level, type 2 airway inflammation, and numbers of mucosal IL-33-positive cells and mast cells associated with augmented epithelial MUC5AC and IFN-α/ß immunostaining was noted after BT in responders, whereas the numbers of mucosal IL-33-positive cells were augmented in BT partial responders. Most of these changes were correlated with clinical parameters. Subepithelial membrane thickening and airway smooth muscle area were similar in the 2 patient groups at baseline and after BT. CONCLUSION: By reducing allergic type 2 inflammation and increasing epithelial MUC5AC and anti-viral IFN-α/ß expression, BT may enhance host immune responses and thus attenuate exacerbations and symptoms in BT responders. Instead, targeting IL-33 may provide a clinical benefit in BT partial responders.

Non-Coding RNAs as Prognostic Biomarkers: A miRNA Signature Specific for Aggressive Early-Stage Lung Adenocarcinomas.

Lung cancer burden can be reduced by adopting primary and secondary prevention strategies such as anti-smoking campaigns and low-dose CT screening for high risk subjects (aged >50 and smokers >30 packs/year). Recent CT screening trials demonstrated a stage-shift towards earlier stage lung cancer and reduction of mortality (~20%). However, a sizable fraction of patients (30-50%) with early stage disease still experience relapse and an adverse prognosis. Thus, the identification of effective prognostic biomarkers in stage I lung cancer is nowadays paramount. Here, we applied a multi-tiered approach relying on coupled RNA-seq and miRNA-seq data analysis of a large cohort of lung cancer patients (TCGA-LUAD, n = 510), which enabled us to identify prognostic miRNA signatures in stage I lung adenocarcinoma. Such signatures showed high accuracy (AUC ranging between 0.79 and 0.85) in scoring aggressive disease. Importantly, using a network-based approach we rewired miRNA-mRNA regulatory networks, identifying a minimal signature of 7 miRNAs, which was validated in a cohort of FFPE lung adenocarcinoma samples (CSS, n = 44) and controls a variety of genes overlapping with cancer relevant pathways. Our results further demonstrate the reliability of miRNA-based biomarkers for lung cancer prognostication and make a step forward to the application of miRNA biomarkers in the clinical routine.

A malignant inflammatory myofibroblastic tumor of the hypopharynx harboring the 3a/b variants of the EML4-ALK fusion gene.

Inflammatory myofibroblastic tumors (IMT) in the head and neck region are rare neoplasms that generally mimic benign/low-grade neoplasms. Overexpression of anaplastic lymphoma kinase (ALK) has been reported in 50% of IMT cases, secondary to ALK activation by structural rearrangements in the ALK gene, which results in a fusion protein with echinoderm microtubule associated protein like 4 (EML4) in ~20% of cases. The present study describes a case of a 74-year-old woman with a malignant IMT in the right posterior hypopharynx harboring a previously unreported chromosomal rearrangement resulting in EML4 and ALK gene fusion. Strong ALK immunoreactivity was observed in neoplastic cells, while fluorescent in situ hybridization combined with fluorescent fragment analysis and direct sequencing identified the first case of the 3a/b variants of the EML4-ALK fusion gene in IMT. The results of the current study highlight the uncommon occurrence of ALK-positive IMT in the head/neck region and demonstrate the importance of integrating different molecular methodologies to identify unequivocal gene fusion characterization.