| 1. |
- Broström, Julia M., et al.
(author)
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Toluene diisocyanate exposure and autotaxin–lysophosphatidic acid signalling
- 2018
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In: Toxicology and Applied Pharmacology. - : Elsevier BV. - 0041-008X .- 1096-0333. ; 355, s. 43-51
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Journal article (peer-reviewed)abstract
- Toluene diisocyanate (TDI) is a reactive chemical used in manufacturing plastics. TDI exposure adversely affects workers' health, causing occupational asthma, but individuals differ in susceptibility. We recently suggested a role for signalling mediated by the enzyme autotaxin (ATX) and its product, lysophosphatidic acid (LPA), in TDI toxicity. Here we genotyped 118 TDI-exposed workers for six single-nucleotide polymorphisms (SNPs) in genes encoding proteins implicated in ATX–LPA signalling: purinergic receptor P2X7 (P2RX7), C–C motif chemokine ligand 2 (CCL2), interleukin 1β (IL1B), and caveolin 1 (CAV1). Two P2RX7 SNPs (rs208294 and rs2230911) significantly modified the associations between a biomarker of TDI exposure (urinary 2,4-toluene diamine) and plasma LPA; two IL1B SNPs (rs16944 and rs1143634) did not. CAV1 rs3807989 modified the associations, but the effect was not statistically significant (p = 0.05–0.09). In vitro, TDI-exposed bronchial epithelial cells (16HBE14o-) rapidly released ATX and IL-1β. P2X7 inhibitors attenuated both responses, but confocal microscopy showed non-overlapping localizations of ATX and IL-1β, and down-regulation of CAV1 inhibited the ATX response but not the IL-1β response. This study indicates that P2X7 is pivotal for TDI-induced ATX–LPA signalling, which was modified by genetic variation in P2RX7. Furthermore, our data suggest that the TDI-induced ATX and IL-1β responses occur independently.
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| 2. |
- Broström, Julia, et al.
(author)
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Toluene diisocyanate: Induction of the autotaxin-lysophosphatidic acid axis and its association with airways symptoms.
- 2015
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In: Toxicology and Applied Pharmacology. - : Elsevier BV. - 1096-0333 .- 0041-008X. ; 287:3, s. 222-231
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Journal article (peer-reviewed)abstract
- Diisocyanates are industrial chemicals which have a wide range of applications in developed and developing countries. They are notorious lung toxicants and respiratory sensitizers. However, the mechanisms behind their adverse effects are not adequately characterized. Autotaxin (ATX) is an enzyme producing lysophosphatidic acid (LPA), and the ATX-LPA axis has been implicated in lung related inflammatory conditions and diseases, including allergic asthma, but not to toxicity of environmental low-molecular-weight chemicals. We investigated effects of toluene diisocyanate (TDI) on ATX induction in human lung epithelial cell models, and we correlated LPA-levels in plasma to biomarkers of TDI exposure in urine collected from workers exposed to <5ppb (parts per billion). Information on workers' symptoms was collected through interviews. One nanomolar TDI robustly induced ATX release within 10min in vitro. A P2X7- and P2X4-dependent microvesicle formation was implicated in a rapid ATX release and a subsequent protein synthesis. Co-localization between purinergic receptors and ATX was documented by immunofluorescence and confocal microscopy. The release was modulated by monocyte chemoattractant protein-1 (MCP-1) and by extracellular ATP. In workers, we found a dose-response relationship between TDI exposure biomarkers in urine and LPA levels in plasma. Among symptomatic workers reporting "sneezing", the LPA levels were higher than among non-symptomatic workers. This is the first report indicating induction of the ATX-LPA axis by an environmental low-molecular-weight chemical, and our data suggest a role for the ATX-LPA axis in TDI toxicity.
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| 3. |
- Ghalali, Aram
(author)
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Akt signaling and coordinated changes in the distribution and expression of Akt-regulating phosphatases
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Cancer is one of the major causes of death worldwide. The PI3K/Akt signaling pathway is up-regulated in a variety of human cancers. Akt is an important signaling molecule in cellular survival pathways. Activated Akt (pAkt) is able to induce protein synthesis pathways, and is therefore a key protein involved in growth and prevention of apoptosis. Several lipid or protein phosphatases exist that inhibit Akt signaling. Nuclear localization of pAkt is crucial for its activity and function. Previously, it was demonstrated that cholesterol-lowering and anti-carcinogenic drugs, statins, rapidly depleted nuclear pAkt. We focused on the mechanism behind this rapid nuclear pAkt depletion. In paper I our results showed that statins or extracellular ATP induced a complex and coordinated response in insulin-stimulated A549 cells leading to depletion of nuclear pAkt. This involved lipid/protein phosphatases PTEN, PHLPP1 and -2, PP2A and calcineurin. Purinergic P2X7 receptor was identified to be a mediator of this effect. In study II, the rapid nuclear pAkt depletion was further investigated and the possible role of a PI3K subunit, p110β, was elucidated. This subunit has been associated with aggressive prostate cancer, and studies on mouse embryonic fibroblast cells and cancer cells showed that p110β is essential for nuclear pAkt depletion. EHBP1 and P-Rex1 have been involved in protein transport and membrane recruitment of proteins, and both of these proteins have been associated with aggressive or invasive prostate cancer. In paper III we found that P2X7 correlated with aggressive prostate cancer and that P2X7-mediated rapid nuclear pAkt depletion is dependent of both EHBP1 and P-Rex1. Moreover, pharmacological concentrations of statins decreased nuclear pAkt in non-transformed prostatic cells, suggesting that the anticancer effect of statins might be mediated by inhibition of the Akt pathway. In Paper IV we characterized crosstalk between PHLPPs and PTEN, two proteins that down-regulate Akt activity. This crosstalk was seen in cancer cells and TGFβ-1-activated prostate stem cells, and had an impact on cellular invasiveness. The P2X4 receptor was identified to be a mediator of crosstalk induction. Downstream of P2X4 epigenetic and transcriptional factors were activated. Overall, these studies show a novel mechanism leading to nuclear pAkt depletion. We also provide evidence for a role of P2X7-EHBP1-Akt axis in prostate cancer development and that inhibition of Akt may affect the invasive capacity of the cancer cells. A crosstalk between Akt phosphatases regulates Akt and affects invasiveness.
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| 4. |
- Nilchian, Azadeh, et al.
(author)
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CXADR-Mediated Formation of an AKT Inhibitory Signalosome at Tight Junctions Controls Epithelial-Mesenchymal Plasticity in Breast Cancer.
- 2019
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In: Cancer Research. - : American Association for Cancer Research. - 0008-5472 .- 1538-7445. ; 79:1, s. 47-60
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Journal article (peer-reviewed)abstract
- Tight junctions (TJ) act as hubs for intracellular signaling pathways controlling epithelial cell fate and function. Deregulation of TJ is a hallmark of epithelial-mesenchymal transition (EMT), which contributes to carcinoma progression and metastasis. However, the signaling mechanisms linking TJ to the induction of EMT are not understood. Here we identify a TJ-based signalosome, which controls AKT signaling and EMT in breast cancer. The coxsackie- and adenovirus receptor (CXADR), a TJ protein with an essential yet uncharacterized role in organogenesis and tissue homeostasis, was identified as a key component of the signalosome. CXADR regulated the stability and function of the phosphatases and AKT inhibitors PTEN and PHLPP2. Loss of CXADR led to hyper-activation of AKT and sensitized cells to TGF-β1-induced EMT. Conversely, restoration of CXADR stabilized PHLPP2 and PTEN, inhibited AKT, and promoted epithelial differentiation. Loss of CXADR in luminal A breast cancer correlated with loss of PHLPP2 and PTEN and poor prognosis. These results show that CXADR promotes the formation of an AKT-inhibitory signalosome at TJ and regulates epithelial-mesenchymal plasticity in breast cancer cells. Moreover, loss of CXADR might be used as a prognostic marker in luminal breast cancer.
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