Bleomycin induces upregulation of lysyl oxidase in cultured human fetal lung fibroblasts

Aim: To investigate the mechanism of bleomycin (BLM)-induced pulmonary fibrosis. Methods: Cultured human fetal lung fibroblast (HLF) cells were exposed to bleomycin (BLM) at 0-30 mu g/mL for 24 h. Western blot analysis was used to detect lysyl oxidase (LO) protein expression. Real-time RT-PCR was used to detect LO mRNA level. LO catalytic activity was measured using diaminopentane as a substrate and Amplex red as a hydrogen peroxide probe. Copper (Cu) concentration was detected by flame atomic absorption spectrophotometry. Results: Exposure of HLF cells to BLM at 10 mu g/mL and 30 mu g/mL increased LO catalytic activity to 130% and 158% of the control in the conditioned media. The expression of LO mRNA was increased to 5.5-fold of the control in HLF cells exposure to BLM at 3 mu g/mL. BLM at 3 mu g/mL also increased the expression of 46 kDa preproLO, 50 kDa proLO and 32 kDa mature LO to 219%, 130%, and 135% of the control, respectively. The Cu concentrations in conditioned media of cultured HLF cells exposed to BLM (10 and 30 mu g/mL) were increased significantly to 1.48 and 2.46-fold of the control, respectively. Conclusion: Bleomycin induces upregulation of LO in cultured human fetal lung fibroblasts, which may be the mechanism of bleomycin-induced pulmonary fibrosis.