A novel EGFR-tyrosine kinase inhibitor (TKI), osimertinib, has marked efficacy in patients with EGFR-mutated lung cancer. However, some patients show intrinsic resistance and an insufficient response ...to osimertinib. This study showed that osimertinib stimulated AXL by inhibiting a negative feedback loop. Activated AXL was associated with EGFR and HER3 in maintaining cell survival and inducing the emergence of cells tolerant to osimertinib. AXL inhibition reduced the viability of EGFR-mutated lung cancer cells overexpressing AXL that were exposed to osimertinib. The addition of an AXL inhibitor during either the initial or tolerant phases reduced tumor size and delayed tumor re-growth compared to osimertinib alone. AXL was highly expressed in clinical specimens of EGFR-mutated lung cancers and its high expression was associated with a low response rate to EGFR-TKI. These results indicated pivotal roles for AXL and its inhibition in the intrinsic resistance to osimertinib and the emergence of osimertinib-tolerant cells.
Drug tolerance is the basis for acquired resistance to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) including osimertinib, through mechanisms that still remain unclear. ...Here, we show that while AXL-low expressing EGFR mutated lung cancer (EGFRmut-LC) cells are more sensitive to osimertinib than AXL-high expressing EGFRmut-LC cells, a small population emerge osimertinib tolerance. The tolerance is mediated by the increased expression and phosphorylation of insulin-like growth factor-1 receptor (IGF-1R), caused by the induction of its transcription factor FOXA1. IGF-1R maintains association with EGFR and adaptor proteins, including Gab1 and IRS1, in the presence of osimertinib and restores the survival signal. In AXL-low-expressing EGFRmut-LC cell-derived xenograft and patient-derived xenograft models, transient IGF-1R inhibition combined with continuous osimertinib treatment could eradicate tumors and prevent regrowth even after the cessation of osimertinib. These results indicate that optimal inhibition of tolerant signals combined with osimertinib may dramatically improve the outcome of EGFRmut-LC.
Epidemiologic studies have found that obesity is associated with malignant grade and mortality in prostate cancer. Several adipokines have been implicated as putative mediating factors between ...obesity and prostate cancer. Fatty acid binding protein 4 (FABP4), a member of the cytoplasmic fatty acid binding protein multigene family, was recently identified as a novel adipokine. Although FABP4 is released from adipocytes and mean circulating concentrations of FABP4 are linked with obesity, effects of exogenous FABP4 on prostate cancer progression are unclear. In this study, we examined the effects of exogenous FABP4 on human prostate cancer cell progression. FABP4 treatment promoted serum‐induced prostate cancer cell invasion in vitro. Furthermore, oleic acid promoted prostate cancer cell invasion only if FABP4 was present in the medium. These promoting effects were reduced by FABP4 inhibitor, which inhibits FABP4 binding to fatty acids. Immunostaining for FABP4 showed that exogenous FABP4 was taken up into DU145 cells in three‐dimensional culture. In mice, treatment with FABP4 inhibitor reduced the subcutaneous growth and lung metastasis of prostate cancer cells. Immunohistochemical analysis showed that the number of apoptotic cells, positive for cleaved caspase‐3 and cleaved PARP, was increased in subcutaneous tumors of FABP4 inhibitor‐treated mice, as compared with control mice. These results suggest that exogenous FABP4 might promote human prostate cancer cell progression by binding with fatty acids. Additionally, exogenous FABP4 activated the PI3K/Akt pathway, independently of binding to fatty acids. Thus, FABP4 might be a key molecule to understand the mechanisms underlying the obesity‐prostate cancer progression link.
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Obesity is associated with malignancy and poor prognosis in prostate cancer (PC). In this study, the authors found that an adipokine called “fatty‐acid binding protein 4” (FABP4) promoted PC‐cell invasion in vitro. FABP4 also activated the PI3K/Akt pathway in PC cells. FABP4 inhibitor, which inhibits FABP4 binding to fatty acids, reduced this invasiveness in vitro, as well as tumor growth and lung metastasis in vivo. FABP4 may therefore play a key role in the molecular mechanisms underlying the connection between obesity and prostate‐cancer progression.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The p53 and EGFR pathways are frequently altered in bladder cancer, yet their contributions to its progression remain elusive. Here we report that DEAD box polypeptide 31 (DDX31) plays a critical ...role in the multistep progression of muscle-invasive bladder cancer (MIBC) through its sequential interactions with mutant p53 (mutp53) and EGFR. In early MIBC cells, nuclear DDX31-bound mutp53/SP1 enhanced mutp53 transcriptional activation, leading to migration and invasion of MIBC. Cytoplasmic DDX31 also bound EGFR and phospho-nucleolin in advanced MIBC, leading to EGFR-Akt signaling activation. High expression of both cytoplasmic DDX31 and p53 proteins correlated with poor prognosis in patients with MIBC, and blocking the DDX31/NCL interaction resulted in downregulation of EGFR/Akt signaling, eliciting an
antitumor effect against bladder cancer. These findings reveal that DDX31 cooperates with mutp53 and EGFR to promote progression of MIBC, and inhibition of DDX31/NCL formation may lead to potential treatment strategies for advanced MIBC.
DDX31 cooperates with mutp53 and EGFR to promote progression of muscle invasive bladder cancer.
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Abstract
The sensing of various extrinsic stimuli triggers the receptor-interacting protein kinase-3 (RIPK3)-mediated signaling pathway, which leads to mixed-lineage kinase-like (MLKL) ...phosphorylation followed by necroptosis. Although necroptosis is a form of cell death and is involved in inflammatory conditions, the roles of necroptosis in acute pancreatitis (AP) remain unclear. In the current study, we administered caerulein to
Ripk3-
or
Mlkl-
deficient mice (Ripk3
−/−
or Mlkl
−/−
mice, respectively) and assessed the roles of necroptosis in AP. We found that Ripk3
−/−
mice had significantly more severe pancreatic edema and inflammation associated with macrophage and neutrophil infiltration than control mice. Consistently, Mlkl
−/−
mice were more susceptible to caerulein-induced AP, which occurred in a time- and dose-dependent manner, than control mice. Mlkl
−/−
mice exhibit weight loss, edematous pancreatitis, necrotizing pancreatitis, and acinar cell dedifferentiation in response to tissue damage. Genetic deletion of
Mlkl
resulted in downregulation of the antiapoptotic genes
Bclxl
and
Cflar
in association with increases in the numbers of apoptotic cells, as detected by TUNEL assay. These findings suggest that RIPK3 and MLKL-mediated necroptosis exerts protective effects in AP and caution against the use of necroptosis inhibitors for AP treatment.
For non‐small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations, the initial therapeutic interventions will have crucial impacts on their clinical outcomes. ...Drug tolerant factors reportedly have an impact on EGFR‐tyrosine kinase inhibitor sensitivity. This prospective study investigated the impacts of drug tolerant‐related protein expression in tumors based on the efficacy of osimertinib in the first‐setting of EGFR‐mutated advanced NSCLC patients. A total of 92 patients with EGFR‐mutated advanced or postoperative recurrent NSCLC were analyzed and treated with osimertinib at 14 institutions in Japan. AXL, p53, and programmed death‐ligand 1 (PD‐L1) expression in patient tumors was determined using immunohistochemistry. The AXL signaling pathway was investigated using a cell line‐based assay and AXL‐related gene expression in The Cancer Genome Atlas (TCGA) database. High levels of AXL and positive‐p53 expression were detected in 26.1% and 53.3% of the pretreatment EGFR‐mutated NSCLC tumors, respectively. High AXL expression levels were significantly associated with a shorter progression‐free survival compared with low AXL expression levels, irrespective of the EGFR activating mutation status (p = 0.026). Cell line‐based assays indicated that the overexpression of AXL protein accelerated PD‐L1 expression, which induced insensitivity to osimertinib. In the TCGA database, AXL RNA levels were positively correlated with PD‐L1 expression in the lung adenocarcinoma cohort. The results show that high AXL expression levels in tumors impact clinical predictions when using osimertinib to treat EGFR‐mutated NSCLC patients. Trial Registration: UMIN000043942.
High levels of AXL and PD‐L1 expression predicts poor PFS with osimertinib. AXL protein overexpression induces PD‐L1 expression and osimertinib insensitivity. AXL expression in tumors impacts clinical predictions when using osimertinib.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Proteasomes are multisubunit proteases that play a critical role in maintaining cellular function through the selective degradation of ubiquitinated proteins. When 3 additional β subunits, expression ...of which is induced by IFN-γ, are substituted for their constitutively expressed counterparts, the structure is converted to an immunoproteasome. However, the underlying roles of immunoproteasomes in human diseases are poorly understood. Using exome analysis, we found a homozygous missense mutation (G197V) in immunoproteasome subunit, β type 8 (PSMB8), which encodes one of the β subunits induced by IFN-γ in patients from 2 consanguineous families. Patients bearing this mutation suffered from autoinflammatory responses that included recurrent fever and nodular erythema together with lipodystrophy. This mutation increased assembly intermediates of immunoproteasomes, resulting in decreased proteasome function and ubiquitin-coupled protein accumulation in the patient's tissues. In the patient's skin and B cells, IL-6 was highly expressed, and there was reduced expression of PSMB8. Downregulation of PSMB8 inhibited the differentiation of murine and human adipocytes in vitro, and injection of siRNA against Psmb8 in mouse skin reduced adipocyte tissue volume. These findings identify PSMB8 as an essential component and regulator not only of inflammation, but also of adipocyte differentiation, and indicate that immunoproteasomes have pleiotropic functions in maintaining the homeostasis of a variety of cell types.
Platelet-derived growth factor (PDGF) has been implicated in the pathogenesis of pulmonary fibrosis. Nintedanib, a multi-kinase inhibitor that targets several tyrosine kinases, including PDGF ...receptor (PDGFR), was recently approved as an anti-fibrotic agent to reduce the deterioration of FVC in patients with idiopathic pulmonary fibrosis (IPF). However, the effects of PDGFR-α or -β on pulmonary fibrosis remain unclear. In an attempt to clarify their effects, we herein used blocking antibodies specific for PDGFR-α (APA5) and -β (APB5) in a bleomycin (BLM)-induced pulmonary fibrosis mouse model. The effects of these treatments on the growth of lung fibroblasts were examined using the 3H-thymidine incorporation assay in vitro. The anti-fibrotic effects of these antibodies were investigated with the Ashcroft score and collagen content of lungs treated with BLM. Their effects on inflammatory cells in the lungs were also analyzed using bronchoalveolar lavage fluid. We investigated damage to epithelial cells and the proliferation of fibroblasts in the lungs. APA5 and APB5 inhibited the phosphorylation of PDGFR-α and -β as well as the proliferation of lung fibroblasts induced by PDGF-AA and BB. The administration of APB5, but not APA5 effectively inhibited BLM-induced pulmonary fibrosis in mice. Apoptosis and the proliferation of epithelial cells and fibroblasts were significantly decreased by the treatment with APB5, but not by APA5. The late treatment with APB5 also ameliorated fibrosis in lungs treated with BLM. These results suggest that PDGFR-α and -β exert different effects on BLM-induced pulmonary fibrosis in mice. A specific approach using the blocking antibody for PDGFR-β may be useful for the treatment of pulmonary fibrosis.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The prostate is surrounded by periprostatic adipose tissue. Although adipose tissue was thought to play limited physiological roles, it has recently been recognized as an active endocrine organ, ...secreting growth factors and adipokines. Epidemiologically, obesity is associated with prostate cancer progression. A major mechanism to explain the link between obesity and cancer includes the insulin and insulin‐like growth factor (IGF)‐1 axis, sex steroids, and adipokines. When prostate cancer cells invade periprostatic adipose tissue, adipose tissue contributes to create the tumor microenvironment, mainly via adipokine secretion. Furthermore, direct crosstalk between adipocytes and cancer cells can exist. We showed that fatty acid‐binding protein 4 (FABP4) released from adipocytes was taken up into prostate cancer cells and may act as a carrier of an energy source for the invasion. Bone is an adipocyte‐rich organ and is the common metastatic site of prostate cancer. In the microenvironment of bone metastases, tumor cells, osteoblasts, osteoclasts, adipocytes, and other stromal cells are interacting with one another and organizing a complex system. Thus, growing evidence implicates adipose tissue as a critical contributor to the development of prostate cancer. A deeper understanding of the mechanisms leads to more effective therapeutic strategies for prostate cancer. J. Med. Invest. 65:9‐17, February, 2018
Nintedanib, a tyrosine kinase inhibitor that is specific for platelet-derived growth factor receptors (PDGFR), fibroblast growth factor receptors (FGFR), and vascular endothelial growth factor ...receptors (VEGFR), has recently been approved for idiopathic pulmonary fibrosis. Fibrocytes are bone marrow-derived progenitor cells that produce growth factors and contribute to fibrogenesis in the lungs. However, the effects of nintedanib on the functions of fibrocytes remain unclear.
Human monocytes were isolated from the peripheral blood of healthy volunteers. The expression of growth factors and their receptors in fibrocytes was analyzed using ELISA and Western blotting. The effects of nintedanib on the ability of fibrocytes to stimulate lung fibroblasts were examined in terms of their proliferation. The direct effects of nintedanib on the differentiation and migration of fibrocytes were also assessed. We investigated whether nintedanib affected the accumulation of fibrocytes in mouse lungs treated with bleomycin.
Human fibrocytes produced PDGF, FGF2, and VEGF-A. Nintedanib and specific inhibitors for each growth factor receptor significantly inhibited the proliferation of lung fibroblasts stimulated by the supernatant of fibrocytes. Nintedanib inhibited the migration and differentiation of fibrocytes induced by growth factors in vitro. The number of fibrocytes in the bleomycin-induced lung fibrosis model was reduced by the administration of nintedanib, and this was associated with anti-fibrotic effects.
These results support the role of fibrocytes as producers of and responders to growth factors, and suggest that the anti-fibrotic effects of nintedanib are at least partly mediated by suppression of fibrocyte function.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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