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Background Exploratory biomarker analysis was conducted to identify factors related to the outcomes of patients with stage II/III gastric cancer using data from the Adjuvant Chemotherapy Trial of S-1 for Gastric Cancer, which was a randomized controlled study comparing the administration of an orally active combination of tegafur, gimeracil, and oteracil with surgery alone. Methods Formalin-fixed paraffin-embedded surgical specimens from 829 patients were retrospectively examined, and 63 genes were analyzed by quantitative real-time RT-PCR after TaqMan assay-based pre-amplification. Gene expression was normalized to the geometric mean of GAPDH , ACTB , and RPLP0 as reference genes, and categorized into low and high values based on the median. The impact of gene expression on survival was analyzed using 5-year survival data. The Benjamini and Hochberg procedure was used to control the false discovery rate. Results IGF1R and AREG were most strongly correlated with overall survival, which was significantly worse in high IGF1R patients than low IGF1R patients, but better in high AREG patients than low AREG patients. The hazard ratio for death in the analysis of overall survival (S-1 vs. surgery alone) was reduced in the high IGF1R group compared with the low IGF1R group and in the low AREG group compared with the high AREG group. There were no significant interaction effects. Conclusion IGF1R gene expression was associated with poor outcomes after curative resection of stage II/III gastric cancer, whereas AREG gene expression was associated with good outcomes. No significant interaction effect on survival was evident between S-1 treatment and gene expression.

Myocardial ischemia–reperfusion injury (IRI) leads to the stabilization of the transcription factors hypoxia-inducible factor 1-alpha (HIF1-alpha) and hypoxia-inducible factor 2-alpha (HIF2-alpha). While previous studies implicate HIF1-alpha in cardioprotection, the role of HIF2-alpha remains elusive. Here we show that HIF2-alpha induces the epithelial growth factor amphiregulin (AREG) to elicit cardioprotection in myocardial IRI. Comparing mice with inducible deletion of Hif1a or Hif2a in cardiac myocytes, we show that loss of Hif2-alpha increases infarct sizes. Microarray studies in genetic models or cultured human cardiac myocytes implicate HIF2-alpha in the myocardial induction of AREG. Likewise, AREG increases in myocardial tissues from patients with ischemic heart disease. Areg deficiency increases myocardial IRI, as does pharmacologic inhibition of Areg signaling. In contrast, treatment with recombinant Areg provides cardioprotection and reconstitutes mice with Hif2a deletion. These studies indicate that HIF2-alpha induces myocardial AREG expression in cardiac myocytes, which increases myocardial ischemia tolerance. Myocardial ischemia–reperfusion injury stabilizes the hypoxia-inducible factor HIF2-alpha. Here, the authors show that HIF2-alpha protects the heart from injury via induction of the epidermal growth factor amphiregulin, and that amphiregulin administration is cardioprotective in mice.

Background Airway fibrosis is one of the pathological characteristics of severe asthma. Transforming growth factor (TGF)-β has been known to promote epithelial-mesenchymal transition formation and to play a role in the progression of tissue fibrosis. Cellular communication network factor 2 (CCN2) and fibronectin (FN) are well-known markers of EMT and fibrosis. However, whether AREG is involved in TGF-β-induced CCN2 and FN expression in human lung epithelial cells is unknown. Methods AREG and FN were analyzed by immunofluorescence staining on ovalbumin-challenged mice. CCN2 and FN expression were evaluated in human lung epithelial (A459) cells following TGF or AREG treatment for the indicated times. Secreted AREG from A549 cells was detected by ELISA. Cell migration was observed by a wound healing assay. Chromatin immunoprecipitation was used to detect the c-Jun binding to the CCN2 promoter. Results AREG and FN expression colocalized in lung tissues from mice with ovalbumin-induced asthma by immunofluorescence staining. Moreover, TGF-β caused the release of AREG from A549 cells into the medium. Smad3 siRNA down-regulated AREG expression. AREG also stimulated CCN2 and FN expression, JNK and c-Jun phosphorylation, and cell migration in A549 cells. AREG small interfering (si) RNA inhibited TGF-β-induced expression of CCN2, FN, and cell migration. Furthermore, AREG-induced CCN2 and FN expression were inhibited by EGFR siRNA, a JNK inhibitor (SP600125), and an activator protein-1 (AP-1) inhibitor (curcumin). EGFR siRNA attenuated AREG-induced JNK and c-Jun phosphorylation. Moreover, SP600125 downregulated AREG-induced c-Jun phosphorylation. Conclusion These results suggested that AREG mediates the TGF-β-induced EMT in human lung epithelial cells through EGFR/JNK/AP-1 activation. Understanding the role of AREG in the EMT could foster the development of therapeutic strategies for airway remodeling in severe asthma.

Non-small cell lung cancer (NSCLC) remains the leading cause of cancer-related deaths worldwide. The majority of patients are diagnosed in advanced disease stage. Bone metastasis is the most frequent complication in NSCLC resulting in osteolytic lesions. The perfect balance between bone-resorbing osteoclasts and bone-forming osteoblasts activity is lost in bone metastasis, inducing osteoclastogenesis. In NSCLC, the epidermal growth factor receptor (EGFR) pathway is constitutively activated. EGFR binds Amphiregulin (AREG) that is overexpressed in several cancers such as colon, breast and lung. Its levels in plasma of NSCLC patients correlate with poor prognosis and AREG was recently found as a signaling molecule in exosomes derived from cancer cell lines. Exosomes have a key role in the cell-cell communication and they were recently indicated as important actors in metastatic niche preparation. In the present work, we hypothesize a role of AREG carried by exosomes derived from NSCLC in bone metastasis induction. We observed that NSCLC-exosomes, containing AREG, induce EGFR pathway activation in pre-osteoclasts that in turn causes an increased expression of RANKL. RANKL is able to induce the expression of proteolytic enzymes, well-known markers of osteoclastogenesis, triggering a vicious cycle in osteolytic bone metastasis.

The airway epithelium serves as the interface between the host and external environment. In many chronic lung diseases, the airway is the site of substantial remodeling after injury. While, idiopathic pulmonary fibrosis (IPF) has traditionally been considered a disease of the alveolus and lung matrix, the dominant environmental (cigarette smoking) and genetic (gain of function MUC5B promoter variant) risk factor primarily affect the distal airway epithelium. Moreover, airway-specific pathogenic features of IPF include bronchiolization of the distal airspace with abnormal airway cell-types and honeycomb cystic terminal airway-like structures with concurrent loss of terminal bronchioles in regions of minimal fibrosis. However, the pathogenic role of the airway epithelium in IPF is unknown. Combining biophysical, genetic, and signaling analyses of primary airway epithelial cells, we demonstrate that healthy and IPF airway epithelia are biophysically distinct, identifying pathologic activation of the ERBB-YAP axis as a specific and modifiable driver of prolongation of the unjammed-to-jammed transition in IPF epithelia. Furthermore, we demonstrate that this biophysical state and signaling axis correlates with epithelial-driven activation of the underlying mesenchyme. Our data illustrate the active mechanisms regulating airway epithelial-driven fibrosis and identify targets to modulate disease progression. Environmental and genetic risk factors affect the distal airway epithelium in idiopatic pulmonary fibrosis (IPF) but the role of the epithelium in IPF remains unclear. Here the authors show that pathologic activation of the ERBB-YAP axis induces dynamic and structural dysfunction in the distal airway epithelium eliciting a pro-fibrotic phenotype in mesenchymal cells.

Aging is characterized by a progressive loss of physiological integrity, while cancer represents one of the primary pathological factors that severely threaten human lifespan and healthspan. In clinical oncology, drug resistance limits the efficacy of most anticancer treatments, and identification of major mechanisms remains a key to solve this challenging issue. Here, we highlight the multifaceted senescence‐associated secretory phenotype (SASP), which comprises numerous soluble factors including amphiregulin (AREG). Production of AREG is triggered by DNA damage to stromal cells, which passively enter senescence in the tumor microenvironment (TME), a process that remarkably enhances cancer malignancy including acquired resistance mediated by EGFR. Furthermore, paracrine AREG induces programmed cell death 1 ligand (PD‐L1) expression in recipient cancer cells and creates an immunosuppressive TME via immune checkpoint activation against cytotoxic lymphocytes. Targeting AREG not only minimized chemoresistance of cancer cells, but also restored immunocompetency when combined with classical chemotherapy in humanized animals. Our study underscores the potential of in vivo SASP in driving the TME‐mediated drug resistance and shaping an immunosuppressive niche, and provides the proof of principle of targeting major SASP factors to improve therapeutic outcome in cancer medicine, the success of which can substantially reduce aging‐related morbidity and mortality. The senescence‐associated secretory phenotype (SASP) comprises numerous soluble factors including AREG. Intensively produced by treatment‐damaged stroma, AREG drives cancer‐acquired resistance and induces passive formation of an immunosuppressive niche. Experimentally detectable in the circulating blood, AREG is both a stroma‐derived SASP factor meriting therapeutic intervention and a novel noninvasive biomarker to predict adverse outcome of post‐treatment cancer patients in clinical medicine.

Cancer cells have higher reactive oxygen species (ROS) than normal cells, due to genetic and metabolic alterations. An emerging scenario is that cancer cells increase ROS to activate protumorigenic signaling while activating antioxidant pathways to maintain redox homeostasis. Here we show that, in basal-like and BRCA1-related breast cancer (BC), ROS levels correlate with the expression and activity of the transcription factor aryl hydrocarbon receptor (AhR). Mechanistically, ROS triggers AhR nuclear accumulation and activation to promote the transcription of both antioxidant enzymes and the epidermal growth factor receptor (EGFR) ligand, amphiregulin (AREG). In a mouse model of BRCA1-related BC, cancer-associated AhR and AREG control tumor growth and production of chemokines to attract monocytes and activate proangiogenic function of macrophages in the tumor microenvironment. Interestingly, the expression of these chemokines as well as infiltration of monocyte-lineage cells (monocyte and macrophages) positively correlated with ROS levels in basal-like BC. These data support the existence of a coordinated link between cancer-intrinsic ROS regulation and the features of tumor microenvironment. Therapeutically, chemical inhibition of AhR activity sensitizes human BC models to Erlotinib, a selective EGFR tyrosine kinase inhibitor, suggesting a promising combinatorial anticancer effect of AhR and EGFR pathway inhibition. Thus, AhR represents an attractive target to inhibit redox homeostasis and modulate the tumor promoting microenvironment of basal-like and BRCA1-associated BC.

Chronic rejection (CR) after organ transplantation is alloimmune injury manifested by graft vascular remodeling and fibrosis that is resistant to immunosuppression. Single-cell RNA-Seq analysis of MHC class II–mismatched (MHCII-mismatched) heart transplants developing chronic rejection identified graft IL-33 as a stimulator of tissue repair pathways in infiltrating macrophages and Tregs. Using IL-33–deficient donor mice, we show that graft fibroblast–derived IL-33 potently induced amphiregulin (Areg) expression by recipient Tregs. The assessment of clinical samples also confirmed increased expression of Areg by intragraft Tregs also during rejection. Areg is an EGF secreted by multiple immune cells to shape immunomodulation and tissue repair. In particular, Areg is proposed to play a major role in Treg-mediated muscle, epithelium, and nerve repair. Assessment of recipient mice with Treg-specific deletion of Areg surprisingly uncovered that Treg secretion of Areg contributed to CR. Specifically, heart transplants from recipients with Areg-deficient Tregs showed less fibrosis, vasculopathy, and vessel-associated fibrotic niches populated by recipient T cells. Mechanistically, we show that Treg-secreted Areg functioned to increase fibroblast proliferation. In total, these studies identify how a dysregulated repair response involving interactions between IL-33 + fibroblasts in the allograft and recipient Tregs contributed to the progression of CR.

The fibrotic progression of diseases is characterized by the excessive deposition of extracellular matrix (ECM) proteins, leading to an alteration in tissue structure, often based on the activation of epithelial-to-mesenchymal transition (EMT). This can lead to decreased or completely impaired organ function, compromising quality of life and affecting vital organs. Fibrotic phenomena have recently been observed in autoimmune diseases and are correlated with the activation of transduction cascades that trigger chronic inflammation. Currently, effective therapeutic options remain limited due to the numerous molecular mechanisms that are activated and intersect with each other. Amphiregulin (AREG), a ligand for the epidermal growth factor receptor (EGFR), is involved in physiological cellular processes, but emerging data suggest that it plays a key role as a protein located at the crossroads of various activation mechanisms. The critical role of AREG as a molecular bridge between inflammatory and fibrotic mechanisms has aroused our interest in deepening our understanding of AREG involvement in the fibrotic processes identified, to date, in inflammatory autoimmune diseases. The aim of this review is to evaluate emerging targeted interventions to modulate AREG-mediated molecular pathways in fibrotic processes observed in autoimmune diseases, starting with the structure of AREG and the molecular mechanisms in which the protein is involved.

Repair of the lung epithelium after injury is a critical component for resolution; however, the processes necessary to drive epithelial resolution are not clearly defined. Published data demonstrate that Foxp3+ regulatory T cells (Tregs) enhance alveolar epithelial proliferation after injury, and Tregs in vitro directly promote type II alveolar epithelial cell (AT2) proliferation, in part by a contact-independent mechanism. Therefore, we sought to determine the contribution of Treg-specific expression of a growth factor that is known to be important in lung repair, keratinocyte growth factor (kgf). The data demonstrate that Tregs express kgf and that Treg-specific expression of kgf regulates alveolar epithelial proliferation during the resolution phase of acute lung injury and in a model of regenerative alveologenesis in vivo. In vitro experiments demonstrate that AT2 cells cocultured with Tregs lacking kgf have decreased rates of proliferation compared with AT2 cells cocultured with wild-type Tregs. Moreover, Tregs isolated from lung tissue and grown in culture express higher levels of two growth factors that are important for lung repair (kgf and amphiregulin) compared with Tregs isolated from splenic tissue. Lastly, Tregs isolated from human lung tissue can be stimulated ex vivo to induce kgf expression. This study reveals mechanisms by which Tregs direct tissue-reparative effects during resolution after acute lung injury, further supporting the emerging role of Tregs in tissue repair.