PLEK2 mediates metastasis and invasion via α5-nAChR activation in nicotine-induced lung adenocarcinoma.

Evidence has shown a strong relationship between smoking and epithelial mesenchymal transition (EMT). α5-nicotinic acetylcholine receptor (α5-nAChR) contributes to nicotine-induced lung cancer cell EMT. The cytoskeleton-associated protein PLEK2 is mainly involved in cytoskeletal protein recombination and cell stretch migration regulation, which is closely related to EMT. However, little is known about the link between nicotine/α5-nAChR and PLEK2 in lung adenocarcinoma (LUAD). Here, we identified a link between α5-nAChR and PLEK2 in LUAD. α5-nAChR expression was correlated with PLEK2 expression, smoking status and lower survival in vivo. α5-nAChR mediated nicotine-induced PLEK2 expression via STAT3. α5-nAChR/PLEK2 signaling is involved in LUAD cell migration, invasion and stemness. Moreover, PLEK2 was found to interact with CFL1 in nicotine-induced EMT in LUAD cells. Furthermore, the functional link among α5-nAChR, PLEK2 and CFL1 was confirmed in mouse xenograft tissues and human LUAD tissues. These findings reveal a novel α5-nAChR/PLEK2/CFL1 pathway involved in nicotine-induced LUAD progression.

Effect of hyperthermia on intestinal microecology, immune function, and progression-free survival in patients with advanced unresectable lung adenocarcinoma.

This study aims to investigate the effects of hyperthermia on intestinal microecology, immune function, and progression-free survival of patients with advanced unresectable lung adenocarcinoma. A total of twenty patients with lung adenocarcinoma in the study group received the advanced standard first-line treatment protocol, which included pemetrexed + cisplatin combined with sintilimab immunotherapy and hyperthermia. Additionally, twenty patients with lung adenocarcinoma in the control group received the advanced standard first-line treatment protocol, which included pemetrexed + cisplatin combined with sintilimab immunotherapy. The T-lymphocyte subpopulation and CD4/CD8 cell ratio of each sample were detected using flow cytometry. The intestinal flora was evaluated using 16S rRNA gene sequencing. The study observed the changes in the abundance, distribution, composition, and structure of fecal gut microorganisms before and after the treatment in both groups of patients. Significant differences were observed in the intestinal flora between the two groups. The patients in the study group showed improved immunity after treatment, whereas there was no significant change in the immunity of the control group before and after treatment. However, the difference in progression-free survival between the two groups was not statistically significant. Hyperthermia has a significant impact on improving the microecology of intestinal flora and the immunity of patients, but it does not have a significant effect on prolonging the progression-free survival of patients.

Ubiquitin Ligases Siah1a/2 Control Alveolar Macrophage Functions to Limit Carcinogen-Induced Lung Adenocarcinoma.

Cellular components of the tumor microenvironment, including myeloid cells, play important roles in the progression of lung adenocarcinoma (LUAD) and its response to therapy. Here, we characterize the function of the ubiquitin ligases Siah1a/2 in regulating the differentiation and activity of alveolar macrophages (AM) and assess the implication of Siah1a/2 control of AMs for carcinogen-induced LUAD. Macrophage-specific genetic ablation of Siah1a/2 promoted accumulation of AMs with an immature phenotype and increased expression of protumorigenic and pro-inflammatory Stat3 and ß-catenin gene signatures. Administration of urethane to wild-type mice promoted enrichment of immature-like AMs and lung tumor development, which was enhanced by macrophage-specific Siah1a/2 ablation. The profibrotic gene signature seen in Siah1a/2-ablated immature-like macrophages was associated with increased tumor infiltration of CD14+ myeloid cells and poorer survival of patients with LUAD. Single-cell RNA-seq confirmed the presence of a cluster of immature-like AMs expressing a profibrotic signature in lungs of patients with LUAD, a signature enhanced in smokers. These findings identify Siah1a/2 in AMs as gatekeepers of lung cancer development. SIGNIFICANCE: The ubiquitin ligases Siah1a/2 control proinflammatory signaling, differentiation, and profibrotic phenotypes of alveolar macrophages to suppress lung carcinogenesis.

Lung adenocarcinoma promotion by air pollutants.

A complete understanding of how exposure to environmental substances promotes cancer formation is lacking. More than 70 years ago, tumorigenesis was proposed to occur in a two-step process: an initiating step that induces mutations in healthy cells, followed by a promoter step that triggers cancer development1. Here we propose that environmental particulate matter measuring ≤2.5 µm (PM2.5), known to be associated with lung cancer risk, promotes lung cancer by acting on cells that harbour pre-existing oncogenic mutations in healthy lung tissue. Focusing on EGFR-driven lung cancer, which is more common in never-smokers or light smokers, we found a significant association between PM2.5 levels and the incidence of lung cancer for 32,957 EGFR-driven lung cancer cases in four within-country cohorts. Functional mouse models revealed that air pollutants cause an influx of macrophages into the lung and release of interleukin-1ß. This process results in a progenitor-like cell state within EGFR mutant lung alveolar type II epithelial cells that fuels tumorigenesis. Ultradeep mutational profiling of histologically normal lung tissue from 295 individuals across 3 clinical cohorts revealed oncogenic EGFR and KRAS driver mutations in 18% and 53% of healthy tissue samples, respectively. These findings collectively support a tumour-promoting role for  PM2.5 air pollutants  and provide impetus for public health policy initiatives to address air pollution to reduce disease burden.

[Life-threatening flare of an underlying «paraneoplastic¼ dermatomyositis in a patient with lung adenocarcinoma treated with anti-PD-1 pembrolizuma]. / Poussée sévère d'une dermatomyosite pré-existante chez une patiente avec un adénocarcinome pulmonaire traité par pembrolizumab, un anti-PD-1.

Dermatomyositis is an autoimmune disease mainly characterized by muscle and skin involvement. Its association with cancer is known but the term «paraneoplastic¼ remains debated. We report here the case of a 71-year-old woman with a new diagnosis of dermatomyositis with, at the same time, the discovery of a lung adenocarcinoma. Lung cancer was treated with pembrolizumab, an immune checkpoint inhibitor directed against the "Programmed cell Death protein 1" (PD-1) receptor. Three weeks later, the patient presented a severe flare of dermatomyositis. Administration of intravenous corticosteroids and infliximab were ineffective. Intravenous immunoglobulins were then administered, followed by subcutaneous methotrexate, with a progressive positive evolution. Flares of pre-existing autoimmune diseases are observed under immune check point inhibitors, even when the evolution of the cancer is favourable. These immune-related adverse events are often «mild to moderate¼ and severe immune related side effects are not more frequent when the patient has a pre-existing autoimmune disease. Treatment can be maintained in the majority of cases. However, as demonstrated in this clinical case, although immune checkpoint inhibitors are not contraindicated in autoimmune diseases, the presence of myositis requires special attention given the potential severity of flares.

: La dermatomyosite est une maladie auto-immune principalement caractérisée par une atteinte musculaire et cutanée. Son association avec le cancer est connue, mais le terme «paranéoplasique¼ reste débattu. Nous rapportons ici le cas d'une patiente de 71 ans avec un nouveau diagnostic de dermatomyosite et, au même moment, la découverte d'un adénocarcinome pulmonaire. La néoplasie pulmonaire a été traitée par pembrolizumab, un inhibiteur des points de contrôle immunitaire dirigé contre le récepteur «Programmed cell Death protein 1¼ (PD-1). Trois semaines plus tard, la patiente présentera une poussée sévère de dermatomyosite, ne répondant pas à la corticothérapie intraveineuse ni à l'infliximab. Des immunoglobulines intraveineuses sont alors administrées, suivies de méthotrexate sous-cutané, avec une évolution progressivement positive. On observe des poussées de maladies auto-immunes préexistantes sous inhibiteurs de points de contrôle immunitaire, même quand l'évolution néoplasique est favorable. Ces effets secondaires immuno-induits sont souvent «légers à modérés¼ et on n'observe pas plus de manifestations indésirables «sévères¼ lorsque le patient présente une maladie auto-immune pré-existante. Le traitement peut être maintenu dans la majorité des cas. Toutefois, comme démontré dans ce cas clinique, bien que les inhibiteurs de points de contrôle immunitaire ne soient pas contre-indiqués en cas de maladie auto-immune, la présence d'une myosite nécessite une attention particulière vu la gravité potentielle des poussées.

PM2.5 exposure and risk of lung adenocarcinoma in women of Taiwan: A case-control study with density sampling.

BACKGROUND AND OBJECTIVE: The prevalence of smoking among women in Taiwan is <5%, but the incidence of lung cancer remains high. This study determined the association between PM2.5 (fine particulate matter with an aerodynamic diameter of ≤2.5 µm) exposure and lung cancer among women in Taiwan. METHODS: In total, 21,301 female lung cancer cases nationwide were newly diagnosed between 2012 and 2017. Each case was age-, sex- and calendar year-matched with four controls randomly selected from the general population. Allowing a latent period of 5 years, we estimated the PM2.5 and nitrogen dioxide (NO2 ) exposures for each individual according to the residential changes from 2000. We adopted self-reported smoking statuses for the cases, while those of controls were estimated using annual surveys in each residential county. We performed multiple logistic regression analyses to examine the associations between PM2.5 and NO2 exposures and incident lung cancer cases. RESULTS: The ORs of lung adenocarcinoma for the third (30.5-35.1 µg/m3 ), fourth (35.1-39.3 µg/m3 ) and fifth PM2.5 exposure quintiles (39.3-48.1 µg/m3 ) relative to the first quintile were 1.10 (95% CI: 1.04-1.16), 1.12 (95% CI: 1.06-1.19) and 1.10 (95% CI: 1.04-1.16), respectively, after adjusting for smoking, residence and comorbidities. A dose-response relationship (p = 0.004) was found. The associations persisted with a 10-year latency and were not detected for small-cell and squamous cell carcinoma after control for smoking. We did not observe a similar effect for NO2 exposure. CONCLUSION: Residential PM2.5 exposure higher than 30 µg/m3 was associated with an increased risk of lung adenocarcinoma in women of Taiwan.

Utilization and costs of epidermal growth factor receptor mutation testing and targeted therapy in Medicare patients with metastatic lung adenocarcinoma.

BACKGROUND: Guidelines in 2013 and 2014 recommended Epidermal Growth Factor Receptor (EGFR) testing for metastatic lung adenocarcinoma patients as the efficacy of targeted therapies depends on the mutations. However, adherence to these guidelines and the corresponding costs have not been well-studied. METHODS: We identified 2362 patients at least 65 years old newly diagnosed with metastatic lung adenocarcinoma from January 2013 to December 2015 using the SEER-Medicare database. We examined the utilization patterns of EGFR testing and targeted therapies including erlotinib and afatinib. We further examined the costs of both EGFR testing and targeted therapy in terms of Medicare costs and patient out-of-pocket (OOP) costs. RESULTS: The EGFR testing rate increased from 38% in 2013 to 51% and 49% in 2014 and 2015 respectively. The testing rate was 54% among the 394 patients who received erlotinib, and 52% among the 42 patients who received afatinib. The median Medicare and OOP costs for testing were $1483 and $293. In contrast, the costs for targeted therapy were substantially higher with median 30-day costs at $6114 and $240 for erlotinib and $6239 and $471 for afatinib. CONCLUSION: This population-based study suggests that testing guidelines improved the use of EGFR testing, although there was still a large proportion of patients receiving targeted therapy without testing. The costs of targeted therapy were substantially higher than the testing costs, highlighting the need to improve adherence to testing guidelines in order to improve clinical outcomes while reducing the economic burden for both Medicare and patients.

Proton pump inhibitors reduce the survival of advanced lung cancer patients with therapy of gefitinib or erlotinib.

Gefitinib and erlotinib are the first-line tyrosine kinase inhibitors (TKI) for advanced non-small-cell lung cancer. However, co-administration of either drug with proton pump inhibitors (PPI) or histamine-2 receptor antagonists (H2RA) may reduce TKI's bioavailability. Therefore, we aimed to investigate the effects of these drug-drug interactions. We surveyed nationwide population-based databases between Jan 1, 2010, and Dec 30, 2018. Newly diagnosed patients with advanced lung adenocarcinoma who received first-line gefitinib or erlotinib were identified. Effects on overall survival (OS) and time to next treatment (TTNT) association between PPIs or H2RAs and co-administrated gefitinib or erlotinib were evaluated. PPIs or H2RAs users were defined if the period overlapped with TKIs by ≥ 20%. A total of 4340 gefitinib and 1635 erlotinib users were included. PPI group had the shortest median OS and TTNT compared to the H2RA and non-user groups (in gefitinib cohort: OS: 14.35 vs. 17.67 vs. 21.87 months; P < 0.0001, TTNT: 8.47 vs. 10.78 vs. 10.33 months; P < 0.0001); (in erlotinib cohort: OS: 16.97 vs. 20.07 vs. 23.92 months; P < 0.0001, TTNT: 9.06 vs. 11.85 vs. 10.90 months; P = 0.0808). Compared with the non-user group, the adjusted hazard ratio (aHR) of the PPI group in the gefitinib was 1.58 on OS (95% CI 1.42-1.76), 1.37 on TTNT (95% CI 1.24-1.52); in the erlotinib was 1.54 on OS (95% CI 1.30-1.82) and 1.19 on TTNT (95% CI 1.01-1.39). Concurrent use of PPIs with first-line gefitinib or erlotinib therapy was associated with a worse OS and TTNT in patients with lung adenocarcinoma harboring EGFR mutations.

Severe pembrolizumab-induced gastritis in a patient with lung adenocarcinoma.

Cancer immunotherapy is an increasingly common treatment option based on anti-tumor immune response. However, a challenge is arising regarding its potential, which is the poorly understood recognized immune-mediated adverse effects.

Fatal Autoimmune Storm After a Single Cycle of Anti-PD-1 Therapy: A Case of Lethal Toxicity but Pathological Complete Response in Metastatic Lung Adenocarcinoma.

As immunotherapy agents are incorporated into the routine oncological practice, the number of patients at the risk of immune-related adverse events has increased dramatically. However, the prompt identification and effective management of severe autoimmune complications remain a challenge. We report the case of a patient with metastatic lung adenocarcinoma who experienced a fatal autoimmune storm 3 weeks after the first dose of anti-programmed death receptor-1 (PD-1) agent pembrolizumab, which included thyroiditis, hepatitis, myositis, myocarditis, pneumonitis, and myasthenia gravis. Aggressive autoimmunity was supported by extensive T-cell and macrophage tissue infiltrates and autoantibody positivity. Remarkably, no residual tumor was found at autopsy. This case illustrates the potential harm caused by immunotherapy and our limited knowledge on its prevention, treatment, and association to antitumor efficacy.

Low-Coverage Whole Genome Sequencing Using Laser Capture Microscopy with Combined Digital Droplet PCR: An Effective Tool to Study Copy Number and Kras Mutations in Early Lung Adenocarcinoma Development.

Defining detailed genomic characterization of early tumor progression is critical to identifying key regulators and pathways in carcinogenesis as potentially druggable targets. In human lung cancer, work to characterize early cancer development has mainly focused on squamous cancer, as the earliest lesions are more proximal in the airways and often accessible by repeated bronchoscopy. Adenocarcinomas are typically located distally in the lung, limiting accessibility for biopsy of pre-malignant and early stages. Mouse lung cancer models recapitulate many human genomic features and provide a model for tumorigenesis with pre-malignant atypical adenomatous hyperplasia and in situ adenocarcinomas often developing contemporaneously within the same animal. Here, we combined tissue characterization and collection by laser capture microscopy (LCM) with digital droplet PCR (ddPCR) and low-coverage whole genome sequencing (LC-WGS). ddPCR can be used to identify specific missense mutations in Kras (Kirsten rat sarcoma viral oncogene homolog, here focused on Kras Q61) and estimate the percentage of mutation predominance. LC-WGS is a cost-effective method to infer localized copy number alterations (CNAs) across the genome using low-input DNA. Combining these methods, the histological stage of lung cancer can be correlated with appearance of Kras mutations and CNAs. The utility of this approach is adaptable to other mouse models of human cancer.

Covalent N-arylation by the pollutant 1,2-naphthoquinone activates the EGF receptor.

The epidermal growth factor receptor (EGFR) is the most intensively investigated receptor tyrosine kinase. Several EGFR mutations and modifications have been shown to lead to abnormal self-activation, which plays a critical role in carcinogenesis. Environmental air pollutants, which are associated with cancer and respiratory diseases, can also activate EGFR. Specifically, the environmental electrophile 1,2-naphthoquinone (1,2-NQ), a component of diesel exhaust particles and particulate matter more generally, has previously been shown to impact EGFR signaling. However, the detailed mechanism of 1,2-NQ function is unknown. Here, we demonstrate that 1,2-NQ is a novel chemical activator of EGFR but not other EGFR family proteins. We found that 1,2-NQ forms a covalent bond, in a reaction referred to as N-arylation, with Lys80, which is in the ligand-binding domain. This modification activates the EGFR-Akt signaling pathway, which inhibits serum deprivation-induced cell death in a human lung adenocarcinoma cell line. Our study reveals a novel mode of EGFR pathway activation and suggests a link between abnormal EGFR activation and environmental pollutant-associated diseases such as cancer.

Syngeneic tobacco carcinogen-induced mouse lung adenocarcinoma model exhibits PD-L1 expression and high tumor mutational burden.

Human lung adenocarcinoma (LUAD) in current or former smokers exhibits a high tumor mutational burden (TMB) and distinct mutational signatures. Syngeneic mouse models of clinically relevant smoking-related LUAD are lacking. We established and characterized a tobacco-associated, transplantable murine LUAD cell line, designated FVBW-17, from a LUAD induced by the tobacco carcinogen 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone in the FVB/N mouse strain. Whole-exome sequencing of FVBW-17 cells identified tobacco-associated KrasG12D and Trp53 mutations and a similar mutation profile to that of classic alkylating agents with a TMB greater than 500. FVBW-17 cells transplanted subcutaneously, via tail vein, and orthotopically generated tumors that were histologically similar to human LUAD in FVB/N mice. FVBW-17 tumors expressed programmed death ligand 1 (PD-L1), were infiltrated with CD8+ T cells, and were responsive to anti-PD-L1 therapy. FVBW-17 cells were also engineered to express green fluorescent protein and luciferase to facilitate detection and quantification of tumor growth. Distant metastases to lung, spleen, liver, and kidney were observed from subcutaneously transplanted tumors. This potentially novel cell line is a robust representation of human smoking-related LUAD biology and provides a much needed preclinical model in which to test promising new agents and combinations, including immune-based therapies.

K-Ras-Activated Cells Can Develop into Lung Tumors When Runx3-Mediated Tumor Suppressor Pathways Are Abrogated.

K-RAS is frequently mutated in human lung adenocarcinomas (ADCs), and the p53 pathway plays a central role in cellular defense against oncogenic K-RAS mutation. However, in mouse lung cancer models, oncogenic K-RAS mutation alone can induce ADCs without p53 mutation, and loss of p53 does not have a significant impact on early K-RAS-induced lung tumorigenesis. These results raise the question of how K-RAS-activated cells evade oncogene surveillance mechanisms and develop into lung ADCs. RUNX3 plays a key role at the restriction (R)-point, which governs multiple tumor suppressor pathways including the p14ARF-p53 pathway. In this study, we found that K-RAS activation in a very limited number of cells, alone or in combination with p53 inactivation, failed to induce any pathologic lesions for up to 1 year. By contrast, when Runx3 was inactivated and K-RAS was activated by the same targeting method, lung ADCs and other tumors were rapidly induced. In a urethane-induced mouse lung tumor model that recapitulates the features of K-RAS-driven human lung tumors, Runx3 was inactivated in both adenomas (ADs) and ADCs, whereas K-RAS was activated only in ADCs. Together, these results demonstrate that the R-point-associated oncogene surveillance mechanism is abrogated by Runx3 inactivation in AD cells and these cells cannot defend against K-RAS activation, resulting in the transition from AD to ADC. Therefore, K-RAS-activated lung epithelial cells do not evade oncogene surveillance mechanisms; instead, they are selected if they occur in AD cells in which Runx3 has been inactivated.

Destrin Contributes to Lung Adenocarcinoma Progression by Activating Wnt/ß-Catenin Signaling Pathway.

Lung cancer, especially lung adenocarcinoma, is one of the most common neoplasms worldwide. However, the mechanisms underlying its initiation, development, and metastasis are still poorly understood. Destrin (DSTN) is a member of ADF/cofilin family. Its detailed biological function remains unknown, although it is reported that DSTN is involved in cytoskeleton remodeling and regulation of actin filament turnover. Recent evidence has shown that high expression of cofilin-1 is associated with invasion and poor prognosis of several types of human tumors, but the detailed mechanism is still entirely unclear, particularly in lung cancer tumorigenesis and malignancy. Here, we report that DSTN was highly expressed in a mouse lung cancer model induced by urethane and in clinical lung adenocarcinoma tissue samples. Its expression level was positively correlated with cancer development, as well as metastasis to the liver and lymph nodes. Consistently, it was directly associated with the poor prognosis of lung adenocarcinoma patients. Furthermore, we also found that DSTN promotes cell proliferation, invasion, and migration in vitro, and facilitates subcutaneous tumor formation and lung metastasis via intravenous injection in vivo. Mechanically, DSTN associates with and facilitates nuclear translocation of ß-catenin, which promotes epithelial-to-mesenchymal transition (EMT). Taken together, our results indicated that DSTN enhances lung cancer malignancy through facilitating ß-catenin nuclear translocation and inducing EMT. Combined with multivariate analyses, DSTN might potentially serve as a therapeutic target and an independent prognostic marker of lung adenocarcinoma. IMPLICATIONS: This finding indicates that DSTN facilitates ß-catenin nuclear translocation and promotes malignancy in lung adenocarcinoma.

Targeting Opsin4/Melanopsin with a Novel Small Molecule Suppresses PKC/RAF/MEK/ERK Signaling and Inhibits Lung Adenocarcinoma Progression.

The identification of oncogenic biomolecules as drug targets is an unmet need for the development of clinically effective novel anticancer therapies. In this study, we report for the first time that opsin 4/melanopsin (OPN4) plays a critical role in the pathogenesis of non-small cell lung cancer (NSCLC) and is a potential drug target. Our study has revealed that OPN4 is overexpressed in human lung cancer tissues and cells, and is inversely correlated with patient survival probability. Knocking down expression of OPN4 suppressed cells growth and induced apoptosis in lung cancer cells. We have also found that OPN4, a G protein-coupled receptor, interacted with Gα11 and triggered the PKC/BRAF/MEK/ERKs signaling pathway in lung adenocarcinoma cells. Genetic ablation of OPN4 attenuated the multiplicity and the volume of urethane-induced lung tumors in mice. Importantly, our study provides the first report of AE 51310 (1-[(2,5-dichloro-4-methoxyphenyl)sulfonyl]-3-methylpiperidine) as a small-molecule inhibitor of OPN4, suppressed the anchorage-independent growth of lung cancer cells and the growth of patient-derived xenograft tumors in mice. IMPLICATIONS: Overall, this study unveils the role of OPN4 in NSCLC and suggests that targeting OPN4 with small molecules, such as AE 51310 would be interesting to develop novel anticancer therapies for lung adenocarcinoma.

Osteopontin drives KRAS-mutant lung adenocarcinoma.

Increased expression of osteopontin (secreted phosphoprotein 1, SPP1) is associated with aggressive human lung adenocarcinoma (LADC), but its function remains unknown. Our aim was to determine the role of SPP1 in smoking-induced LADC. We combined mouse models of tobacco carcinogen-induced LADC, of deficiency of endogenous Spp1 alleles, and of adoptive pulmonary macrophage reconstitution to map the expression of SPP1 and its receptors and determine its impact during carcinogenesis. Co-expression of Spp1 and mutant KrasG12C in benign cells was employed to investigate SPP1/KRAS interactions in oncogenesis. Finally, intratracheal adenovirus encoding Cre recombinase was delivered to LSL.KRASG12D mice lacking endogenous or overexpressing transgenic Spp1 alleles. SPP1 was overexpressed in experimental and human LADC and portended poor survival. In response to two different smoke carcinogens, Spp1-deficient mice developed fewer and smaller LADC with decreased cellular survival and angiogenesis. Both lung epithelial- and macrophage-secreted SPP1 drove tumor-associated inflammation, while epithelial SPP1 promoted early tumorigenesis by fostering the survival of KRAS-mutated cells. Finally, loss and overexpression of Spp1 was, respectively, protective and deleterious for mice harboring KRASG12D-driven LADC. Our data support that SPP1 is functionally involved in early stages of airway epithelial carcinogenesis driven by smoking and mutant KRAS and may present an important therapeutic target.

The antioxidant N-acetylcysteine protects from lung emphysema but induces lung adenocarcinoma in mice.

Oxidative stress is a major contributor to chronic lung diseases. Antioxidants such as N-acetylcysteine (NAC) are broadly viewed as protective molecules that prevent the mutagenic effects of reactive oxygen species. Antioxidants may, however, increase the risk of some forms of cancer and accelerate lung cancer progression in murine models. Here, we investigated chronic NAC treatment in aging mice displaying lung oxidative stress and cell senescence due to inactivation of the transcription factor JunD, which is downregulated in diseased human lungs. NAC treatment decreased lung oxidative damage and cell senescence and protected from lung emphysema but concomitantly induced the development of lung adenocarcinoma in 50% of JunD-deficient mice and 10% of aged control mice. This finding constitutes the first evidence to our knowledge of a carcinogenic effect of antioxidant therapy in the lungs of aged mice with chronic lung oxidative stress and warrants the utmost caution when considering the therapeutic use of antioxidants.

Electronic-cigarette smoke induces lung adenocarcinoma and bladder urothelial hyperplasia in mice.

Electronic-cigarettes (E-cigs) are marketed as a safe alternative to tobacco to deliver the stimulant nicotine, and their use is gaining in popularity, particularly among the younger population. We recently showed that mice exposed to short-term (12 wk) E-cig smoke (ECS) sustained extensive DNA damage in lungs, heart, and bladder mucosa and diminished DNA repair in lungs. Nicotine and its nitrosation product, nicotine-derived nitrosamine ketone, cause the same deleterious effects in human lung epithelial and bladder urothelial cells. These findings raise the possibility that ECS is a lung and bladder carcinogen in addition to nicotine. Given the fact that E-cig use has become popular in the past decade, epidemiological data on the relationship between ECS and human cancer may not be known for a decade to come. In this study, the carcinogenicity of ECS was tested in mice. We found that mice exposed to ECS for 54 wk developed lung adenocarcinomas (9 of 40 mice, 22.5%) and bladder urothelial hyperplasia (23 of 40 mice, 57.5%). These lesions were extremely rare in mice exposed to vehicle control or filtered air. Current observations that ECS induces lung adenocarcinomas and bladder urothelial hyperplasia, combined with our previous findings that ECS induces DNA damage in the lungs and bladder and inhibits DNA repair in lung tissues, implicate ECS as a lung and potential bladder carcinogen in mice. While it is well established that tobacco smoke poses a huge threat to human health, whether ECS poses any threat to humans is not yet known and warrants careful investigation.