Effects of Inhaled Tobacco Smoke on the Pulmonary Tumor Microenvironment

Critical Role of the Sulfiredoxin-Peroxiredoxin IV Axis in Urethane-Induced Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC), the most common type of lung cancer, etiologically associates with tobacco smoking which mechanistically contributes to oxidative stress to facilitate the occurrence of mutations, oncogenic transformation and aberrantly activated signaling pathways. Our previous reports suggested an essential role of Sulfiredoxin (Srx) in promoting the development of lung cancer in humans, and was causally related to Peroxiredoxin IV (Prx4), the major downstream substrate and mediator of Srx-enhanced signaling. To further explore the role of the Srx-Prx4 axis in de novo lung tumorigenesis, we established Prx4-/- and Srx-/-/Prx4-/- mice in pure FVB/N background. Together with wild-type litter mates, these mice were exposed to carcinogenic urethane and the development of lung tumorigenesis was evaluated. We found that disruption of the Srx-Prx4 axis, either through knockout of Srx/Prx4 alone or together, led to a reduced number and size of lung tumors in mice. Immunohistological studies found that loss of Srx/Prx4 led to reduced rate of cell proliferation and less intratumoral macrophage infiltration. Mechanistically, we found that exposure to urethane increased the levels of reactive oxygen species, activated the expression of and Prx4 in normal lung epithelial cells, while knockout of Prx4 inhibited urethane-induced cell transformation. Moreover, bioinformatics analysis found that the Srx-Prx4 axis is activated in many human cancers, and their increased expression is tightly correlated with poor prognosis in NSCLC patients.

Heterogeneous expression of ACE2, TMPRSS2, and FURIN at single-cell resolution in advanced non-small cell lung cancer

Purpose

Considering the high susceptibility of patients with advanced non-small cell lung cancer (NSCLC) to COVID-19, we explored the susceptible cell types and potential routes of SARS-CoV-2 infection in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) by analyzing the expression patterns of the entry receptor angiotensin converting enzyme 2 (ACE2) and the spike (S) protein priming proteases transmembrane serine protease 2 (TMPRSS2) and FURIN.

Methods

Single-cell transcriptomic analysis of 14 LUSC and 12 LUAD samples was utilized to exhibit the heterogeneous expression of ACE2, TMPRSS2 and FURIN across different cell subsets and individuals.

Results

12 cell types and 33 cell clusters were identified from 26 cancer samples. ACE2, TMPRSS2 and FURIN were heterogeneously expressed across different patients. Among all cell types, ACE2, TMPRSS2 and FURIN were predominately expressed in cancer cells and alveolar cells, and lowly uncovered in other cells. Compared to LUSC, the protein priming proteases (TMPRSS2 and FURIN) were highly found in LUAD samples. However, ACE2 was not differentially expressed in cancer cells between the two cancer types. Moreover, ACE2, TMPRSS2, and FURIN expressions were not higher in any cell type of smokers than non-smokers.

Conclusion

Our research first revealed the heterogeneous expression of ACE2, TMPRSS2, and FURIN in different cell subsets of NSCLC and also across different individuals. These results provide insight into the specific cells targeted by SARS-CoV-2 (i.e., cancer cells and alveolar cells) in patients with advanced NSCLC, and indicate that smoking may be not an independent risk factor for NSCLC combined with COVID-19.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-022-04253-1.

Hotspots and Frontiers in Inflammatory Tumor Microenvironment Research: A Scientometric and Visualization Analysis

Methods: Articles on inflammatory tumor microenvironment were retrieved from the Web of Science Core Collection, and the characteristics of the articles were analyzed by CiteSpace software.

Background: The inflammatory tumor microenvironment is an essential feature of the tumor microenvironment. The way in which it promotes or inhibits tumor progression plays an important role in the outcome of a tumor treatment. This research aims to explore a scientific collaboration network, describe evolution of hotspots, and predict future trends through bibliometric analysis.

Results: A total of 3,534 papers published by 390 institutions in 81 countries/regions were screened, and the annual quantity has been increasing rapidly in the past decades. United States was the leading country and has the most productive institutions in this field. The research topics were mainly focused on inflammation and immunity mediated by crucial factors as well as the mechanisms of angiogenesis. Additionally, the development and application of nanoparticles is currently a novel research frontier with bright prospect.

Conclusion: The present scientometric study provides an overview of inflammatory tumor microenvironment research over the previous decades using quantitative and qualitative methods, and the findings of this study can provide references for researchers focusing on tumor treatment.

Tobacco Smoking Could Accentuate Epithelial-Mesenchymal Transition and Th2-Type Response in Patients With Chronic Rhinosinusitis With Nasal Polyps

Tobacco smoking (TS) has been known as one of the most potent risk factors for airway inflammatory diseases. However, there has been a paucity of information regarding the immunologic alteration mediated by TS in patients with chronic rhinosinusitis with nasal polyps (CRSwNP). To identify the effect of TS, we harvested human tissue samples (never smoker: n=41, current smoker: n=22, quitter: n=23) and analyzed the expression of epithelial-derived cytokines (EDCs) such as IL-25, IL-33, and thymic stromal lymphopoietin. The expressions of Th2 cytokines and total serum IgE showed a type-2 inflammatory alteration by TS. In addition, the epithelial marker E-cadherin and epithelial-mesenchymal transition (EMT)-associated markers (N-cadherin, α-SMA, and vimentin) were evaluated. Histological analysis showed that EDC expressions were upregulated in the current smoker group and downregulated in the quitter group. These expression patterns were consistent with mRNA and protein expression levels. We also found that the local Th2 cytokine expression and IgE class switching, as well as serum IgE levels, were elevated in the current smoker group and showed normal levels in the quitter group. Furthermore, the expressions of E-cadherin decreased while those of N-cadherin, α-SMA, and vimentin increased in the current smoker group compared those in the never smoker group. Taken together, these results indicate that TS contributes to the deterioration of pathogenesis by releasing local EDCs and Th2 cytokines, resulting in EMT in patients with CRSwNP. We verified that alterations of immunological response by TS in sinonasal epithelium can play a vital role in leading to CRSwNP.

METTL3-mediated m6A modification of ZBTB4 mRNA is involved in the smoking-induced EMT in cancer of the lung

N6-methyladenosine (m6A) is an epigenetic modification associated with various tumors, but its role in tumorigenesis remains unexplored. Here, as confirmed by methylated RNA immunoprecipitation sequencing (meRIP-seq) and RNA sequencing (RNA-seq) analyses, exposure of human bronchial epithelial (HBE) cells to cigarette smoke extract (CSE) caused an m6A modification in the 3' UTR of ZBTB4, a transcriptional repressor. For these cells, CSE also elevated methyltransferase-like 3 (METTL3) levels, which increased the m6A modification of ZBTB4. RIP-qPCR illustrated that ZBTB4 was the intent gene of YTHDF2 and that levels of ZBTB4 were decreased in an YTHDF2-dependent mechanism. The lower levels of ZBTB4 were associated with upregulation of EZH2, which enhanced H3K27me3 combining with E-cadherin promoter, causing lower E-cadherin levels and induction of the epithelial-mesenchymal transition (EMT). Further, in the lungs of mice, downregulation of METTL3 alleviated the cigarette smoke (CS)-induced EMT. Further, the expression of METTL3 was high in the lung tissues of smokers and inversely correlated with ZBTB4. Overall, our results show that the METTL3-mediated m6A modification of ZBTB4 via EZH2 is involved in the CS-induced EMT and in lung cancer. These results indicate that m6A modifications are a potential therapeutic target of lung damage induced by CS.

Immune Resistance in Lung Adenocarcinoma

Lung cancer is the leading cancer killer worldwide, imposing grievous challenges for patients and clinicians. The incidence of lung adenocarcinoma (LUAD), the main histologic subtype of lung cancer, is still increasing in current-, ex-, and even non-smokers, whereas its five-year survival rate is approximately 15% as the vast majority of patients usually present with advanced disease at the time of diagnosis. The generation of novel drugs targeting key disease driver mutations has created optimism for the treatment of LUAD, but, as these mutations are not universal, this therapeutic line benefits only a subset of patients. More recently, the advent of targeted immunotherapies and their documented clinical efficacy in many different cancers, including LUAD, have started to change cancer management. Immunotherapies have been developed in order to overcome the cancer's ability to develop mechanisms of immune resistance, i.e., to adapt to and evade the host inflammatory and immune responses. Identifying a cancer's immune resistance mechanisms will likely advance the development of personalized immunotherapies. This review examines the key pathways of immune resistance at play in LUAD and explores therapeutic strategies which can unleash potent antitumor immune responses and significantly improve therapeutic efficacy, quality of life, and survival in LUAD.

Nicotine in Senescence and Atherosclerosis

Cigarette smoke is a known exacerbator of age-related pathologies, such as cardiovascular disease (CVD), atherosclerosis, and cellular aging (senescence). However, the role of nicotine and its major metabolite cotinine is yet to be elucidated. Considering the growing amount of nicotine-containing aerosol use in recent years, the role of nicotine is a relevant public health concern. A number of recent studies and health education sites have focused on nicotine aerosol-induced adverse lung function, and neglected cardiovascular (CV) impairments and diseases. A critical review of the present scientific literature leads to the hypothesis that nicotine mediates the effects of cigarette smoke in the CV system by increasing MAPK signaling, inflammation, and oxidative stress through NADPH oxidase 1 (Nox1), to induce vascular smooth muscle cell (VSMC) senescence. The accumulation of senescent VSMCs in the lesion cap is detrimental as it increases the pathogenesis of atherosclerosis by promoting an unstable plaque phenotype. Therefore, nicotine, and most likely its metabolite cotinine, adversely influence atherosclerosis.