LncRNA MEG3 mediates nickel oxide nanoparticles‐induced pulmonary fibrosis via suppressing TGF‐β1 expression and epithelial‐mesenchymal transition process

Abstract

Nickel oxide nanoparticles (NiO NPs) causes pulmonary fibrosis via activating transforming growth factor-β1 (TGF-β1) in rats, but its upstream regulatory mechanisms are unknown. This study aimed to explore the role of long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) in NiO NPs-induced collagen deposition. Male Wistar rats were intratracheally instilled with NiO NPs (0.015, 0.06, and 0.24 mg/kg b.w.) twice a week for 9 weeks. Human lung adenocarcinoma epithelial cells (A549 cells) were cultured with NiO NPs (25, 50, and 100 μg/ml) to establish collagen deposition model. We discovered that NiO NPs-induced rat pulmonary fibrosis was accompanied by the epithelial-mesenchymal transition (EMT) occurrence and MEG3 down-regulation in rat lung tissues. In cell collagen deposition model, NiO NPs also evoked EMT and decreased MEG3 expression in a dose-dependent manner in A549 cells. By overexpressing MEG3 in A549 cells, we found that MEG3 inhibited the level of TGF-β1, EMT process and collagen formation. Moreover, our data showed that SB431542 (TGF-β1 inhibitor) had an inhibitory effect on NiO NPs-induced EMT and collagen formation. Our results indicated that MEG3 inhibited NiO NPs-induced collagen deposition by regulating TGF-β1-mediated EMT process, which may provide some clues for insighting into the mechanisms of NiO NPs-induced pulmonary fibrosis.

LncRNA MEG3 restrained pulmonary fibrosis induced by NiO NPs via regulating hedgehog signaling pathway‐mediated autophagy

“…Rats were randomly divided into control group and NiO NPs groups (0.015, 0.06, 0.24 mg/kg) (eight rats per group). As we described in previous research, 14 the different concentrations of NiO NP were intratracheally instilled into rats twice a week for nine consecutive weeks. The control group was given an equal volume of 0.9% saline.…”

“…The construction and packaging of lentiviral MEG3 vector and cell infection were carried out according to our previous research. 14 In this study, LV-MEG3 refers to the lentivirus carrying the full-length sequence of MEG3, and LV-NC refers to the lentivirus packaged with empty vectors (negative control). Normal A549 cells (uninfected A549 cells), LV-MEG3 A549 cells (LV-MEG3 infected A549 cells), and LV-NC A549 cells (LV-NC infected A549 cells) were derived from cell lines preserved in our laboratory, and they were treated with 50 mg/ mL NiO NPs for 24 h.…”

“…Primers design and synthesis of Shh, ptch1, Smo, Gli1, and GAPDH were completed by Takara Biotechnology Co., Ltd. (Dalian, China), the primers of P62, Beclin1, and LC3B were performed by Sangon Biotech Co., Ltd. (Shanghai, China), and the primers of MEG3 was provided as mentioned earlier. 14 All primers are listed in Table 1. The relative expression levels of MEG3 and mRNAs were quantified by GAPDH levels, which can be calculated by using the formula 2 (ÀΔΔCt) .…”

“…To investigate the relationship between MEG3 and Hh pathway, we used 50 μg/mL NiO NPs to treat LV-NC A549 cells and LV-MEG3 A549 cells that have been successfully established in our laboratory, and we found MEG3 was significantly up-regulated in LV-MEG3 A549 cells compared with normal A549 cells and LV-NC A549 cells. 14 LV-NC A549 cells and A549 cells untreated with NiO NPs were performed as lentivirus control and negative control, respectively. As shown in Figure 7, there was no difference in the expression of Shh, Moreover, the protein levels of Beclin 1 and LC3BII, as well as the ratio of LC3BII/I in the NiO NPs + LV-MEG3 group were higher than those of NiO NPs group, whereas P62 protein level was lower than that of the NiO NPs group (P < .05).…”

“…13 The expression of MEG3 was decreased in a dose-dependent manner in NiO NPsinduced pulmonary fibrosis. 14 However, the downstream regulatory mechanisms of MEG3 in pulmonary fibrosis are still unclear.…”