The aim of this study is to investigate the molecular mechanisms underlying delayed progressive pulmonary fibrosis a characteristic of subacute paraquat (PQ) poisoning. to PQ around the cytomorphology of A549 cells. The cells were exposed to 0 100 300 or 500 μM PQ for 2 PLX7904 days. Cytomorphology was observed under light microscopy: cells showing rounded morphology aggregation and flotation in the medium were observed after PLX7904 exposure to 300 or 500 μM PQ suggesting the induction of cell death by high-dose and short-term exposure to PQ (Fig. 1A). Significant cell death after exposure to 300 and 500 μM PQ was proved by measuring the lactate dehydrogenase (LDH) liberated from your cells due to membrane injury (Fig. 1B). To evaluate whether cell death by PQ was PLX7904 apoptosis or not caspase9 activation and phosphatidylserine (PS) exposure were examined. After high-dose (300 and 500 μM) exposure to PQ the cleaved (activated) form of caspase9 and the externalization of PS on cell surface was detected by Western blot analysis and annexin V staining respectively (Fig. 1C and 1D). Therefore high-dose exposure to PQ induces apoptotic cell death in A549 cells as reported previously [20 21 Fig 1 High-dose short-term exposure to PQ induces caspase9 activation and subsequent A549 cell death. Loss of E-cadherin during A549 cell death by high-dose PQ exposure We next evaluated whether PQ induces EMT in A549 cells. The cells were exposed to 0 100 300 or 500 μM PQ for 2 days and the expression levels of E-cadherin as well as α-SMA were examined. After high-dose (300 μM PQ as the lowest effective dose) exposure to PQ a decrease in E-cadherin was observed (Fig. 2A) while a decrease in α-SMA was also detected (Fig. 2B). Loss of E-cadherin is one of the features of anoikis-like apoptotic cell death  and decrease of α-SMA during myofibroblast apoptosis have also been reported [23 24 for example due to caspase3-mediated proteolysis . Thus high-dose exposure to PQ induces apoptotic cell death that is accompanied by a decrease in E-cadherin as well as α-SMA implying that PQ-induced cell death is not associated with EMT-like response and therefore might be anoikis. Fig 2 A549 cell death by high-dose short-term PQ treatment is usually accompanied by a decrease in the epithelial cell marker E-cadherin but not by an increase in the mesenchymal cell marker α-SMA. Low-dose long-term PQ exposure induces EMT-like response in A549 cells To investigate further whether PQ PLX7904 induces EMT-like response in A549 cells cells were exposed to low doses (0 10 or 30 μM) of PQ for 6 days. Cells not exposed to PQ showed the cobblestone-like appearance characteristic of epithelial cells (Fig. 3A). In contrast cells exposed to 30 μM PQ showed a morphological transformation into spindle-shaped mesenchymal-like cells (Fig. 3A). It seems that the cell number is usually decreased during PQ exposure (Fig. 3A) probably due to the transient attenuation of cell cycle progression during EMT [25 26 Western blot analysis demonstrated that this expressions of E-cadherin and α-SMA are significantly decreased and increased respectively after exposure to 30 μM PQ (Fig. 3B). Another EMT markers cytokeratin19 (an epithelial marker) and vimentin (a mesenchymal marker) also showed tendencies to decrease and increase respectively after exposure to 30 μM PQ (Fig. 3B). RT-PCR analysis Rabbit Polyclonal to OR1A1. also demonstrated that this levels of E-cadherin and α-SMA mRNAs were significantly reduced and improved respectively after contact with 30 μM PQ (Fig. 3C). Collectively we conclude that low-dose (30 μM) long-term (6 times) PQ publicity induces EMT-like mobile response in A549 cells. Fig 3 Low-dose long-term contact with PQ induces both a reduction in E-cadherin and a rise in α-SMA. Low-dose long-term PQ publicity induces nuclear translocation of EMT-inducing transcription elements in A549 cells Provided the evidences of EMT-like mobile response (Fig. 3) we examined whether EMT-inducing transcription elements ZEB1 Twist and Snail had been turned on during low-dose long-term PQ publicity in A549 cells. Immunofluorescence evaluation demonstrated that ZEB1 and Twist had been localized to nucleus after contact with 30 μM PQ for 6 times (Fig. 4). Although modified subcellular PLX7904 localization of Snail was also seen in the cells during PQ publicity it had been localized in the perinuclear area actually after PQ publicity (Fig. 4). These total results claim that at least two EMT-inducing transcription factors ZEB1 and Twist are activated.