microRNA Expression Profile of Purified Alveolar Epithelial Type II Cells.

Alveolar type II (ATII) cells are essential for the maintenance of the alveolar homeostasis. However, knowledge of the expression of the miRNAs and miRNA-regulated networks which control homeostasis and coordinate diverse functions of murine ATII cells is limited. Therefore, we asked how miRNAs expressed in ATII cells might contribute to the regulation of signaling pathways. We purified "untouched by antibodies" ATII cells using a flow cytometric sorting method with a highly autofluorescent population of lung cells. TaqMan® miRNA low-density arrays were performed on sorted cells and intersected with miRNA profiles of ATII cells isolated according to a previously published protocol. Of 293 miRNAs expressed in both ATII preparations, 111 showed equal abundances. The target mRNAs of bona fide ATII miRNAs were used for pathway enrichment analysis. This analysis identified nine signaling pathways with known functions in fibrosis and/or epithelial-to-mesenchymal transition (EMT). In particular, a subset of 19 miRNAs was found to target 21 components of the TGF-ß signaling pathway. Three of these miRNAs (miR-16-5p, -17-5p and -30c-5p) were down-modulated by TGF-ß1 stimulation in human A549 cells, and concomitant up-regulation of associated mRNA targets (BMPR2, JUN, RUNX2) was observed. These results suggest an important role for miRNAs in maintaining the homeostasis of the TGF-ß signaling pathway in ATII cells under physiological conditions.

T-Cells Expressing a Highly Potent PRAME-Specific T-Cell Receptor in Combination with a Chimeric PD1-41BB Co-Stimulatory Receptor Show a Favorable Preclinical Safety Profile and Strong Anti-Tumor Reactivity.

The hostile tumor microenvironment (TME) is a major challenge for the treatment of solid tumors with T-cell receptor (TCR)-modified T-cells (TCR-Ts), as it negatively influences T-cell efficacy, fitness, and persistence. These negative influences are caused, among others, by the inhibitory checkpoint PD-1/PD-L1 axis. The Preferentially Expressed Antigen in Melanoma (PRAME) is a highly relevant cancer/testis antigen for TCR-T immunotherapy due to broad expression in multiple solid cancer indications. A TCR with high specificity and sensitivity for PRAME was isolated from non-tolerized T-cell repertoires and introduced into T-cells alongside a chimeric PD1-41BB receptor, consisting of the natural extracellular domain of PD-1 and the intracellular signaling domain of 4-1BB, turning an inhibitory pathway into a T-cell co-stimulatory pathway. The addition of PD1-41BB to CD8+ T-cells expressing the transgenic PRAME-TCR enhanced IFN-γ secretion, improved cytotoxic capacity, and prevented exhaustion upon repetitive re-challenge with tumor cells in vitro without altering the in vitro safety profile. Furthermore, a single dose of TCR-Ts co-expressing PD1-41BB was sufficient to clear a hard-to-treat melanoma xenograft in a mouse model, whereas TCR-Ts without PD1-41BB could not eradicate the PD-L1-positive tumors. This cutting-edge strategy supports development efforts to provide more effective TCR-T immunotherapies for the treatment of solid tumors.

The Oncogene ECT2 Contributes to a Hyperplastic, Proliferative Lung Epithelial Cell Phenotype in Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) and lung cancer are progressive lung diseases with a poor prognosis. IPF is a risk factor for the development of lung cancer, and the incidence of lung cancer is increased in patients with IPF. The disease pathogenesis of IPF and lung cancer involves common genetic alterations, dysregulated pathways, and the emergence of hyperplastic and metaplastic epithelial cells. Here, we aimed to identify novel, common mediators that might contribute to epithelial cell reprogramming in IPF. Gene set enrichment analysis of publicly available non-small cell lung cancer and IPF datasets revealed a common pattern of misregulated genes linked to cell proliferation and transformation. The oncogene ECT2 (epithelial cell transforming sequence 2), a guanine nucleotide exchange factor for Rho GTPases, was highly enriched in both IPF and non-small cell lung cancer compared with nondiseased controls. Increased expression of ECT2 was verified by qPCR and Western blotting in bleomycin-induced lung fibrosis and human IPF tissue. Immunohistochemistry demonstrated strong expression of ECT2 staining in hyperplastic alveolar epithelial type II (ATII) cells in IPF, as well as its colocalization with proliferating cell nuclear antigen, a well-known proliferation marker. Increased ECT2 expression coincided with enhanced proliferation of primary mouse ATII cells as analyzed by flow cytometry. ECT2 knockdown in ATII cells resulted in decreased proliferation and collagen I expression in vitro. These data suggest that the oncogene ECT2 contributes to epithelial cell reprogramming in IPF, and further emphasize the hyperplastic, proliferative ATII cell as a potential target in patients with IPF and lung cancer.

Differential effects of Nintedanib and Pirfenidone on lung alveolar epithelial cell function in ex vivo murine and human lung tissue cultures of pulmonary fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease. Repetitive injury and reprogramming of the lung epithelium are thought to be critical drivers of disease progression, contributing to fibroblast activation, extracellular matrix remodeling, and subsequently loss of lung architecture and function. To date, Pirfenidone and Nintedanib are the only approved drugs known to decelerate disease progression, however, if and how these drugs affect lung epithelial cell function, remains largely unexplored. METHODS: We treated murine and human 3D ex vivo lung tissue cultures (3D-LTCs; generated from precision cut lung slices (PCLS)) as well as primary murine alveolar epithelial type II (pmATII) cells with Pirfenidone or Nintedanib. Murine 3D-LTCs or pmATII cells were derived from the bleomycin model of fibrosis. Early fibrotic changes were induced in human 3D-LTCs by a mixture of profibrotic factors. Epithelial and mesenchymal cell function was determined by qPCR, Western blotting, Immunofluorescent staining, and ELISA. RESULTS: Low µM concentrations of Nintedanib (1 µM) and mM concentrations of Pirfenidone (2.5 mM) reduced fibrotic gene expression including Collagen 1a1 and Fibronectin in murine and human 3D-LTCs as well as pmATII cells. Notably, Nintedanib stabilized expression of distal lung epithelial cell markers, especially Surfactant Protein C in pmATII cells as well as in murine and human 3D-LTCs. CONCLUSIONS: Pirfenidone and Nintedanib exhibit distinct effects on murine and human epithelial cells, which might contribute to their anti-fibrotic action. Human 3D-LTCs represent a valuable tool to assess anti-fibrotic mechanisms of potential drugs for the treatment of IPF patients.

Cell-specific expression of runt-related transcription factor 2 contributes to pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease with limited therapeutic options and unknown etiology. IPF is characterized by epithelial cell injury, impaired cellular crosstalk between epithelial cells and fibroblasts, and the formation of fibroblast foci with increased extracellular matrix deposition (ECM). We investigated the role of runt-related transcription factor 2 (RUNX2), a master regulator of bone development that has been linked to profibrotic signaling. RUNX2 expression was up-regulated in lung homogenates from patients with IPF and in experimental bleomycin-induced lung fibrosis. The RUNX2 level correlated with disease severity as measured by decreased diffusing capacity and increased levels of the IPF biomarker, matrix metalloproteinase 7. Nuclear RUNX2 was observed in prosurfactant protein C-positive hyperplastic epithelial cells and was rarely found in myofibroblasts. We discovered an up-regulation of RUNX2 in fibrotic alveolar epithelial type II (ATII) cells as well as an increase of RUNX2-negative fibroblasts in experimental and human pulmonary fibrosis. Functionally, small interfering RNA-mediated RUNX2 knockdown decreased profibrotic ATII cell function, such as proliferation and migration, whereas fibroblasts displayed activation markers and increased ECM expression after RUNX2 knockdown. This study reveals that RUNX2 is differentially expressed in ATII cells vs. fibroblasts in lung fibrosis, which contributes to profibrotic cell function. Cell-specific targeting of RUNX2 pathways may represent a therapeutic approach for IPF.-Mümmler, C., Burgy, O., Hermann, S., Mutze, K., Günther, A., Königshoff, M. Cell-specific expression of runt-related transcription factor 2 contributes to pulmonary fibrosis.

Senolytic drugs target alveolar epithelial cell function and attenuate experimental lung fibrosis ex vivo.

Idiopathic pulmonary fibrosis (IPF) is a devastating lung disease with poor prognosis and limited therapeutic options. The incidence of IPF increases with age, and ageing-related mechanisms such as cellular senescence have been proposed as pathogenic drivers. The lung alveolar epithelium represents a major site of tissue injury in IPF and senescence of this cell population is probably detrimental to lung repair. However, the potential pathomechanisms of alveolar epithelial cell senescence and the impact of senolytic drugs on senescent lung cells and fibrosis remain unknown. Here we demonstrate that lung epithelial cells exhibit increased P16 and P21 expression as well as senescence-associated ß-galactosidase activity in experimental and human lung fibrosis tissue and primary cells.Primary fibrotic mouse alveolar epithelial type (AT)II cells secreted increased amounts of senescence-associated secretory phenotype (SASP) factors in vitro, as analysed using quantitative PCR, mass spectrometry and ELISA. Importantly, pharmacological clearance of senescent cells by induction of apoptosis in fibrotic ATII cells or ex vivo three-dimensional lung tissue cultures reduced SASP factors and extracellular matrix markers, while increasing alveolar epithelial markers.These data indicate that alveolar epithelial cell senescence contributes to lung fibrosis development and that senolytic drugs may be a viable therapeutic option for IPF.

Reduced Frizzled Receptor 4 Expression Prevents WNT/ß-Catenin-driven Alveolar Lung Repair in Chronic Obstructive Pulmonary Disease.

RATIONALE: Chronic obstructive pulmonary disease (COPD), in particular emphysema, is characterized by loss of parenchymal alveolar tissue and impaired tissue repair. Wingless and INT-1 (WNT)/ß-catenin signaling is reduced in COPD; however, the mechanisms thereof, specifically the role of the frizzled (FZD) family of WNT receptors, remain unexplored. OBJECTIVES: To identify and functionally characterize specific FZD receptors that control downstream WNT signaling in impaired lung repair in COPD. METHODS: FZD expression was analyzed in lung homogenates and alveolar epithelial type II (ATII) cells of never-smokers, smokers, patients with COPD, and two experimental COPD models by quantitative reverse transcriptase-polymerase chain reaction, immunoblotting, and immunofluorescence. The functional effects of cigarette smoke on FZD4, WNT/ß-catenin signaling, and elastogenic components were investigated in primary ATII cells in vitro and in three-dimensional lung tissue cultures ex vivo. Gain- and loss-of-function approaches were applied to determine the effects of FZD4 signaling on alveolar epithelial cell wound healing and repair, as well as on expression of elastogenic components. MEASUREMENTS AND MAIN RESULTS: FZD4 expression was reduced in human and experimental COPD lung tissues as well as in primary human ATII cells from patients with COPD. Cigarette smoke exposure down-regulated FZD4 expression in vitro and in vivo, along with reduced WNT/ß-catenin activity. Inhibition of FZD4 decreased WNT/ß-catenin-driven epithelial cell proliferation and wound closure, and it interfered with ATII-to-ATI cell transdifferentiation and organoid formation, which were augmented by FZD4 overexpression. Moreover, FZD4 restoration by overexpression or pharmacological induction led to induction of WNT/ß-catenin signaling and expression of elastogenic components in three-dimensional lung tissue cultures ex vivo. CONCLUSIONS: Reduced FZD4 expression in COPD contributes to impaired alveolar repair capacity.

Noncanonical WNT-5A signaling impairs endogenous lung repair in COPD.

Chronic obstructive pulmonary disease (COPD) is a leading cause of death worldwide. One main pathological feature of COPD is the loss of functional alveolar tissue without adequate repair (emphysema), yet the underlying mechanisms are poorly defined. Reduced WNT-ß-catenin signaling is linked to impaired lung repair in COPD; however, the factors responsible for attenuating this pathway remain to be elucidated. Here, we identify a canonical to noncanonical WNT signaling shift contributing to COPD pathogenesis. We demonstrate enhanced expression of noncanonical WNT-5A in two experimental models of COPD and increased posttranslationally modified WNT-5A in human COPD tissue specimens. WNT-5A was increased in primary lung fibroblasts from COPD patients and induced by COPD-related stimuli, such as TGF-ß, cigarette smoke (CS), and cellular senescence. Functionally, mature WNT-5A attenuated canonical WNT-driven alveolar epithelial cell wound healing and transdifferentiation in vitro. Lung-specific WNT-5A overexpression exacerbated airspace enlargement in elastase-induced emphysema in vivo. Accordingly, inhibition of WNT-5A in vivo attenuated lung tissue destruction, improved lung function, and restored expression of ß-catenin-driven target genes and alveolar epithelial cell markers in the elastase, as well as in CS-induced models of COPD. We thus identify a novel essential mechanism involved in impaired mesenchymal-epithelial cross talk in COPD pathogenesis, which is amenable to therapy.

Cigarette smoke alters the secretome of lung epithelial cells.

Cigarette smoke is the most relevant risk factor for the development of lung cancer and chronic obstructive pulmonary disease. Many of its more than 4500 chemicals are highly reactive, thereby altering protein structure and function. Here, we used subcellular fractionation coupled to label-free quantitative MS to globally assess alterations in the proteome of different compartments of lung epithelial cells upon exposure to cigarette smoke extract. Proteomic profiling of the human alveolar derived cell line A549 revealed the most pronounced changes within the cellular secretome with preferential downregulation of proteins involved in wound healing and extracellular matrix organization. In particular, secretion of secreted protein acidic and rich in cysteine, a matricellular protein that functions in tissue response to injury, was consistently diminished by cigarette smoke extract in various pulmonary epithelial cell lines and primary cells of human and mouse origin as well as in mouse ex vivo lung tissue cultures. Our study reveals a previously unrecognized acute response of lung epithelial cells to cigarette smoke that includes altered secretion of proteins involved in extracellular matrix organization and wound healing. This may contribute to sustained alterations in tissue remodeling as observed in lung cancer and chronic obstructive pulmonary disease.

No involvement of alveolar macrophages in the initiation of carbon nanoparticle induced acute lung inflammation in mice.

BACKGROUND: Carbonaceous nanoparticles (CNP) represent a major constituent of urban particulate air pollution, and inhalation of high CNP levels has been described to trigger a pro-inflammatory response of the lung. While several studies identified specific particle characteristics driving respiratory toxicity of low-solubility and low-toxicity particles such as CNP, the major lung cell type, which initiates and drives that response, remains still uncertain. Since alveolar macrophages (AM) are known to effectively phagocytose inhaled particles and play a crucial role for the initiation of pulmonary inflammation caused by invading microbes, we aimed to determine their role for sterile stimuli such as CNP by profiling the primary alveolar cell compartments of the lung. We exposed C57BL/6 mice to 20 µg CNP by intratracheal instillation and comprehensively investigated the expression of the underlying mediators during a time span of 3 to 72 h in three different lung cell populations: CD45- (negative) structural cells, CD45+ (positive) leukocytes, and by BAL recovered cells. RESULTS: Bronchoalveolar lavage (BAL) analysis revealed an acute inflammatory response characterized by the most prominent culmination of neutrophil granulocytes from 12 to 24 h after instillation, which declined to basal levels by day 7. As early as 3 h after CNP exposure 50 % of the AM revealed particle laden. BAL concentrations and lung gene expression profiles of TNFα, and the neutrophil chemoattractants CXCL1,-2 and-5 preceded the neutrophil recruitment and showed highest levels after 12 h of CNP exposure, pointing to a significant activation of the inflammation-evoking lung cells at this point of time. AM, isolated from lungs 3 to 12 h after CNP instillation, however, did not show a pro-inflammatory signature. On the contrary, gene expression analysis of different lung cell populations isolated 12 h after CNP instillation revealed CD45-, mainly representing alveolar epithelial type II (ATII) cells as major producer of inflammatory CXCL cytokines. Particularly by CD45- cells expressed Cxcl5 proved to be the most abundant chemokine, being 12 h after CNP exposure 24 (±11) fold induced. CONCLUSION: Our data suggests that AM are noninvolved in the initiation of the inflammatory response. ATII cells, which induced highest CXCL levels early on, might in contrast be the driver of acute neutrophilic inflammation upon pulmonary CNP exposure.

Systematic phenotyping and correlation of biomarkers with lung function and histology in lung fibrosis.

To date, phenotyping and disease course prediction in idiopathic pulmonary fibrosis (IPF) primarily relies on lung function measures. Blood biomarkers were recently proposed for diagnostic and outcome prediction in IPF, yet their correlation with lung function and histology remains unclear. Here, we comprehensively assessed biomarkers in liquid biopsies and correlated their abundance with lung function and histology during the onset, progression, and resolution of lung fibrosis, with the aim to more precisely evaluate disease progression in the preclinical model of bleomycin-induced pulmonary fibrosis in vivo. Importantly, the strongest correlation of lung function with histological extent of fibrosis was observed at day 14, whereas lung function was unchanged at days 28 and 56, even when histological assessment showed marked fibrotic lesions. Although matrix metalloproteinase-7 (MMP-7), MMP-9, and PAI-1 were significantly elevated in broncheoalveolar lavage of fibrotic mice, only soluble ICAM-1 (sICAM-1) was elevated in the peripheral blood of fibrotic mice and was strongly correlated with the extent of fibrosis. Importantly, tissue-bound ICAM-1 was also elevated in lung homogenates, with prominent staining in hyperplastic type II alveolar epithelial and endothelial cells. In summary, we show that lung function decline is not a prerequisite for histologically evident fibrosis, particularly during the onset or resolution thereof. Plasma levels of sICAM-1 strongly correlate with the extent of lung fibrosis, and may thus be considered for the assessment of intraindividual therapeutic studies in preclinical studies of pulmonary fibrosis.

Membrane-anchored Serine Protease Matriptase Is a Trigger of Pulmonary Fibrogenesis.

RATIONALE: Idiopathic pulmonary fibrosis (IPF) is a devastating disease that remains refractory to current therapies. OBJECTIVES: To characterize the expression and activity of the membrane-anchored serine protease matriptase in IPF in humans and unravel its potential role in human and experimental pulmonary fibrogenesis. METHODS: Matriptase expression was assessed in tissue specimens from patients with IPF versus control subjects using quantitative reverse transcriptase-polymerase chain reaction, immunohistochemistry, and Western blotting, while matriptase activity was monitored by fluorogenic substrate cleavage. Matriptase-induced fibroproliferative responses and the receptor involved were characterized in human primary pulmonary fibroblasts by Western blot, viability, and migration assays. In the murine model of bleomycin-induced pulmonary fibrosis, the consequences of matriptase depletion, either by using the pharmacological inhibitor camostat mesilate (CM), or by genetic down-regulation using matriptase hypomorphic mice, were characterized by quantification of secreted collagen and immunostainings. MEASUREMENTS AND MAIN RESULTS: Matriptase expression and activity were up-regulated in IPF and bleomycin-induced pulmonary fibrosis. In cultured human pulmonary fibroblasts, matriptase expression was significantly induced by transforming growth factor-ß. Furthermore, matriptase elicited signaling via protease-activated receptor-2 (PAR-2), and promoted fibroblast activation, proliferation, and migration. In the experimental bleomycin model, matriptase depletion, by the pharmacological inhibitor CM or by genetic down-regulation, diminished lung injury, collagen production, and transforming growth factor-ß expression and signaling. CONCLUSIONS: These results implicate increased matriptase expression and activity in the pathogenesis of pulmonary fibrosis in human IPF and in an experimental mouse model. Overall, targeting matriptase, or treatment by CM, which is already in clinical use for other diseases, may represent potential therapies for IPF.

Enolase 1 (ENO1) and protein disulfide-isomerase associated 3 (PDIA3) regulate Wnt/ß-catenin-driven trans-differentiation of murine alveolar epithelial cells.

The alveolar epithelium represents a major site of tissue destruction during lung injury. It consists of alveolar epithelial type I (ATI) and type II (ATII) cells. ATII cells are capable of self-renewal and exert progenitor function for ATI cells upon alveolar epithelial injury. Cell differentiation pathways enabling this plasticity and allowing for proper repair, however, are poorly understood. Here, we applied proteomics, expression analysis and functional studies in primary murine ATII cells to identify proteins and molecular mechanisms involved in alveolar epithelial plasticity. Mass spectrometry of cultured ATII cells revealed a reduction of carbonyl reductase 2 (CBR2) and an increase in enolase 1 (ENO1) and protein disulfide-isomerase associated 3 (PDIA3) protein expression during ATII-to-ATI cell trans-differentiation. This was accompanied by increased Wnt/ß-catenin signaling, as analyzed by qRT-PCR and immunoblotting. Notably, ENO1 and PDIA3, along with T1α (podoplanin; an ATI cell marker), exhibited decreased protein expression upon pharmacological and molecular Wnt/ß-catenin inhibition in cultured ATII cells, whereas CBR2 levels were stabilized. Moreover, we analyzed primary ATII cells from mice with bleomycin-induced lung injury, a model exhibiting activated Wnt/ß-catenin signaling in vivo. We observed reduced CBR2 significantly correlating with surfactant protein C (SFTPC), whereas ENO1 and PDIA3 along with T1α were increased in injured ATII cells. Finally, siRNA-mediated knockdown of ENO1, as well as PDIA3, in primary ATII cells led to reduced T1α expression, indicating diminished cell trans-differentiation. Our data thus identified proteins involved in ATII-to-ATI cell trans-differentiation and suggest a Wnt/ß-catenin-driven functional role of ENO1 and PDIA3 in alveolar epithelial cell plasticity in lung injury and repair.

Coactivator-Associated Arginine Methyltransferase-1 Function in Alveolar Epithelial Senescence and Elastase-Induced Emphysema Susceptibility.

Chronic obstructive pulmonary disease (COPD) is characterized by an irreversible loss of lung function and is one of the most prevalent and severe diseases worldwide. A major feature of COPD is emphysema, which is the progressive loss of alveolar tissue. Coactivator-associated arginine methyltransferase-1 (CARM1) regulates histone methylation and the transcription of genes involved in senescence, proliferation, and differentiation. Complete loss of CARM1 leads to disrupted differentiation and maturation of alveolar epithelial type II (ATII) cells. We thus hypothesized that CARM1 regulates the development and progression of emphysema. To address this, we investigated the contribution of CARM1 to alveolar rarefication using the mouse model of elastase-induced emphysema in vivo and small interfering (si)RNA-mediated knockdown in ATII-like LA4 cells in vitro. We demonstrate that emphysema progression in vivo is associated with a time-dependent down-regulation of CARM1. Importantly, elastase-treated CARM1 haploinsufficient mice show significantly increased airspace enlargement (52.5 ± 9.6 µm versus 38.8 ± 5.5 µm; P < 0.01) and lung compliance (2.8 ± 0.32 µl/cm H2O versus 2.4 ± 0.4 µl/cm H2O; P < 0.04) compared with controls. The knockdown of CARM1 in LA4 cells led to decreased sirtuin 1 expression (0.034 ± 0.003 versus 0.022 ± 0.001; P < 0.05) but increased expression of p16 (0.27 ± 0.013 versus 0.31 ± 0.010; P < 0.5) and p21 (0.81 ± 0.088 versus 1.28 ± 0.063; P < 0.01) and higher ß-galactosidase-positive senescent cells (50.57 ± 7.36% versus 2.21 ± 0.34%; P < 0.001) compared with scrambled siRNA. We further demonstrated that CARM1 haploinsufficiency impairs transdifferentiation and wound healing (32.18 ± 0.9512% versus 8.769 ± 1.967%; P < 0.001) of alveolar epithelial cells. Overall, these results reveal a novel function of CARM1 in regulating emphysema development and premature lung aging via alveolar senescence as well as impaired regeneration, repair, and differentiation of ATII cells.

Cigarette smoke extract affects mitochondrial function in alveolar epithelial cells.

Cigarette smoke is the main risk factor for chronic obstructive pulmonary disease (COPD). Exposure of cells to cigarette smoke induces an initial adaptive cellular stress response involving increased oxidative stress and induction of inflammatory signaling pathways. Exposure of mitochondria to cellular stress alters their fusion/fission dynamics. Whereas mild stress induces a prosurvival response termed stress-induced mitochondrial hyperfusion, severe stress results in mitochondrial fragmentation and mitophagy. In the present study, we analyzed the mitochondrial response to mild and nontoxic doses of cigarette smoke extract (CSE) in alveolar epithelial cells. We characterized mitochondrial morphology, expression of mitochondrial fusion and fission genes, markers of mitochondrial proteostasis, as well as mitochondrial functions such as membrane potential and oxygen consumption. Murine lung epithelial (MLE)12 and primary mouse alveolar epithelial cells revealed pronounced mitochondrial hyperfusion upon treatment with CSE, accompanied by increased expression of the mitochondrial fusion protein mitofusin 2 and increased metabolic activity. We did not observe any alterations in mitochondrial proteostasis, i.e., induction of the mitochondrial unfolded protein response or mitophagy. Therefore, our data indicate an adaptive prosurvival response of mitochondria of alveolar epithelial cells to nontoxic concentrations of CSE. A hyperfused mitochondrial network, however, renders the cell more vulnerable to additional stress, such as sustained cigarette smoke exposure. As such, cigarette smoke-induced mitochondrial hyperfusion, although part of a beneficial adaptive stress response in the first place, may contribute to the pathogenesis of COPD.

Relevance of MET activation and genetic alterations of KRAS and E-cadherin for cetuximab sensitivity of gastric cancer cell lines.

PURPOSE: The therapeutic activity of the epidermal growth factor receptor (EGFR)-directed monoclonal antibody cetuximab in gastric cancer is currently being investigated. Reliable biomarkers for the identification of patients who are likely to benefit from the treatment are not available. The aim of the study was to examine the drug sensitivity of five gastric cancer cell lines towards cetuximab as a single agent and to establish predictive markers for chemosensitivity in this cell culture model. The effect of a combination of cetuximab with chemotherapy was compared between a sensitive and a nonsensitive cell line. METHODS: EGFR expression, activation and localisation, the presence and subcellular localisation of the cell adhesion molecule E-cadherin as well as MET activation were examined by Western blot analysis, flow cytometry and immunofluorescence staining. Cells were treated with varying concentrations of cetuximab and cisplatin and 5-fluorouracil in tumour-relevant concentrations. The biological endpoint was cell viability, which was measured by XTT cell proliferation assay. Response to treatment was evaluated using statistical methods. RESULTS: We assessed the activity of cetuximab in five gastric cancer cell lines (AGS, KATOIII, MKN1, MKN28 and MKN45). The viability of two cell lines, MKN1 and MKN28, was significantly reduced by cetuximab treatment. High EGFR expression and low levels of receptor activation were associated with cetuximab responsiveness. MET activation as well as mutations of KRAS and CDH1 (gene encoding E-cadherin) was associated with cetuximab resistance. CONCLUSION: These data indicate that our examinations may be clinically relevant, and the candidate markers should therefore be tested in clinical studies.

DNA methyltransferase 1 as a predictive biomarker and potential therapeutic target for chemotherapy in gastric cancer.

PURPOSE: DNA methylation contributes to carcinogenesis by mediating transcriptional regulation and chromatin remodelling, which may influence the effect of DNA-damaging drugs. We examined the prognostic and predictive impact of DNA methyltransferase (DNMT) 1 and 3b expression in gastric carcinomas (GC) treated by neoadjuvant chemotherapy. In vitro, DNMT1 expression and chemosensitivity were investigated for a functional relationship and the DNMT inhibitor decitabine (DAC) was tested as an alternative treatment option. PATIENTS AND METHODS: DNMT1/3b expression was analysed immunohistochemically in 127 pretherapeutic biopsies of neoadjuvant (platinum/5-fluorouracil)-treated GC patients and correlated with response and overall survival (OS). Short hairpin RNA technology was used to knockdown DNMT1 in the GC cell line, AGS. The chemosensitivity of GC cell lines to DAC alone and to DAC in combination with cisplatin was analysed by XTT or colony formation assays. RESULTS: High DNMT1 and DNMT3b expression was found in 105/127 (83%) and 79/127 (62%) carcinomas, respectively. Patients with low DNMT1 expression demonstrated a significantly better histopathological/clinical response (P=0.03/P=0.008) and OS (P(log-rank)=0.001). In vitro, knockdown of DNMT1 caused an increased chemosensitivity towards cisplatin. Combined treatment with cisplatin and DAC showed a synergistic effect leading to increased cytotoxicity in the cisplatin-resistant cell line AGS. CONCLUSION: Low DNMT1 expression defines a subgroup of GC patients with better outcomes following platinum/5FU-based neoadjuvant chemotherapy. In vitro data support a functional relationship between DNMT1 and cisplatin sensitivity. Besides its potential use as a predictive biomarker, DNMT1 may represent a promising target for alternative therapeutic strategies for a subset of GC patients.

Expression of class I histone deacetylases (HDAC1 and HDAC2) in oesophageal adenocarcinomas: an immunohistochemical study.

BACKGROUND: Histone deacetylases (HDACs) are enzymes which play a central role in post-translational histone and non-histone protein modification. Deregulation of HDACs has been detected in various human malignancies and may also influence response to chemotherapy. AIMS: To investigate the expression of class I histone deacetylase (HDAC) isoforms 1 and 2 in oesophageal adenocarcinomas. METHODS: 132 primary resected tumours and 48 tumours treated by chemotherapy were analysed. Expression of HDAC1 and HDAC2 was determined by immunohistochemistry, applied on a tissue microarray and on pretherapeutic biopsies, and correlated with pathological features and prognosis. RESULTS: There was negative or low expression of HDAC1 in 54% of tumours, moderate expression in 41% and high expression in 5%. HDAC2 expression was negative or low in 30% of tumours, moderate in 47% and high in 21%. In primary resected tumours, high HDAC2 levels were associated with lymphatic tumour spread and lower tumour differentiation grade. HDAC1 levels were not associated with pT, pN category or tumour differentiation grade. For neoadjuvant treated tumours, there was only a trend for an association with high pretherapeutic HDAC2 expression and tumour regression after chemotherapy. Pretherapeutic HDAC1 levels were not associated with regression after chemotherapy. Survival analysis failed to show any prognostic impact of HDAC1 or HDAC2 expression. CONCLUSIONS: High HDAC2 expression is associated with aggressive tumour behaviour in oesophageal adenocarcinomas. No significant prognostic value could be found with respect to overall survival or an association with response to conventional chemotherapy for HDAC expression. Immunohistochemical determination of HDACs may be useful for prediction of response to specific HDAC inhibitors.

Histone deacetylase (HDAC) 1 and 2 expression and chemotherapy in gastric cancer.

BACKGROUND: Histone deacetylases (HDACs) modulate chromatin and may influence the effect of DNA-damaging drugs. We investigated HDAC1 and -2 expression in gastric carcinomas (GCs) for an association of patient outcome with conventional neoadjuvant chemotherapy. In vitro, HDAC inhibitors were evaluated as alternative treatment options. METHODS: HDAC1/2 expression was analyzed immunohistochemically in 127 pretherapeutic biopsy samples of neoadjuvant (platinum/5-fluorouracil) chemotherapy-treated GC patients and correlated with response and overall survival (OS). Chemosensitivity of four GC cell lines to cisplatin and the HDAC inhibitors suberoylanilide hydroxamic acid (SAHA) and valproic acid was determined by XTT assays. Efficiencies of combined drug schedules were analyzed. RESULTS: High expression of HDAC1/2 was found in 69 (54%) of 127 and 108 (85%) of 127 carcinomas, respectively, and was not associated with response or OS. In patients whose disease responded to therapy, high HDAC1 expression was associated with worse OS (P = 0.005). In cell lines, sequential treatment with SAHA and cisplatin showed synergistic effects irrespective of the initial cisplatin sensitivity. CONCLUSIONS: HDAC1 and -2 expression is not suitable to predict response or survival for neoadjuvant-treated GC patients, but HDAC1 expression may be used for risk stratification in patients whose disease responds to therapy. Sequential treatment with SAHA and cisplatin may represent an alternative treatment option for GC patients.