The function and mechanism of microRNA-92a-3p in lipopolysaccharide-induced acute lung injury.

OBJECTIVES: Sepsis-associated acute lung injury (ALI) is a clinically severe respiratory disorder and remains the leading cause of multiple organ failure and mortality. Herein, we used lipopolysaccharide (LPS) to generate sepsis-induced ALI and try to explore the role and mechanism of microRNA-92a-3p (miR-92a-3p) in this process. METHODS: Mice were intravenously injected with miR-92a-3p agomir, antagomir and negative controls for 3 consecutive days and then were intratracheally instillated by LPS (5 mg/kg) for 12 h. To knock down the endogenous A-kinase anchoring protein 1 (AKAP1), mice were intratracheally injected with recombinant adenovirus carrying the short hairpin RNA targeting AKAP1 (shAkap1) at 1 week before LPS administration. RESULTS: miR-92a-3p level was significantly upregulated in the lungs by LPS injection. miR-92a-3p antagomir reduced LPS-induced intrapulmonary inflammation and oxidative stress, thereby preventing pulmonary injury and dysfunction. In contrast, miR-92a-3p agomir aggravated LPS-induced intrapulmonary inflammation, oxidative stress, pulmonary injury and dysfunction. Moreover, we reported that AKAP1 upregulation was required for the beneficial effects of miR-92a-3p antagomir, and that AKAP1 knockdown completely abolished the anti-inflammatory and antioxidant capacities of miR-92a-3p antagomir. CONCLUSION: Our data identify that miR-92a-3p modulates LPS-induced intrapulmonary inflammation, oxidative stress and ALI via AKAP1 in mice.

MicroRNA-762 Modulates Lipopolysaccharide-induced Acute Lung Injury via SIRT7.

BACKGROUND: Inflammation and oxidative stress contribute to the pathogenesis of lipopolysaccharide (LPS)-induced acute lung injury (ALI). MicroRNA-762 (miR-762) has been implicated in the progression of inflammation and oxidative stress; however, its role in ALI remains unclear. In this study, we aim to investigate the role and underlying mechanisms of miR-762 in LPS-induced ALI. METHODS: Mice were intravenously injected with miR-762 antagomir, agomir or the negative controls for 3 consecutive days and then received a single intratracheal instillation of LPS (5 mg/kg) for 12 h to establish ALI model. Adenoviral vectors were used to knock down the endogenous SIRT7 expression. RESULTS: An increased miR-762 expression was detected in LPS-treated lungs. miR-762 antagomir significantly reduced inflammation, oxidative stress and ALI in mice, while the mice with miR-762 agomir treatment exhibited a deleterious phenotype. Besides, we found that SIRT7 upregulation was essential for the pulmonoprotective effects of miR-762 antagomir, and that SIRT7 silence completely abolished the anti-inflammatory and anti-oxidant capacities of miR-762 antagomir. CONCLUSION: miR-762 is implicated in the pathogenesis of LPS-induced ALI via modulating inflammation and oxidative stress, which depends on its regulation of SIRT7 expression. It might be a valuable therapeutic target for the treatment of ALI.

Overexpression of Ulk2 inhibits proliferation and enhances chemosensitivity to cisplatin in non-small cell lung cancer.

The aim of the present study was to examine the function of unc-51 like autophagy activating kinase 2 (Ulk2) in non-small cell lung cancer (NSCLC). Western blotting was used to analyze the protein expression of Ulk2 in seven pairs of cancerous and adjacent non-cancerous NSCLC specimens. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis was used to determine the mRNA expression of Ulk2 in 20 pairs of tumor and adjacent normal tissues. Two NSCLC cell lines, A549 and H460, were transfected with an Ulk2 overexpression plasmid or empty vector; cell proliferation and chemosensitivity were measured using an MTT assay, and flow cytometry and western blotting were used to evaluate apoptosis. A nude mouse tumorigenesis experiment was used to assess tumor volume in vivo, using A549 cells stably overexpressing Ulk2 and control cells. The protein expression levels of Ulk2 were significantly lower in 6/7 (85.7%) cases of NSCLC compared with in non-cancerous tissues, as determined by western blotting (P<0.05). The mRNA expression levels of Ulk2 were significantly lower in 16/20 (70.0%) NSCLC specimens compared with in non-cancerous tissues, as revealed by RT-qPCR (P<0.05). Overexpression of Ulk2 significantly inhibited the proliferation of A549 and H460 cells (P<0.05) and sensitized the NSCLC cell lines to cisplatin- and etoposide-induced inhibition of proliferation, and to cisplatin-induced apoptosis, with a significant difference identified compared with the control group (P<0.05). Overexpression of Ulk2 significantly increased basal autophagy levels in A549 and H460 cells (P<0.05). Thus, Ulk2-induced enhanced chemosensitivity was suggested to be partly mediated through increased autophagy. The overexpression of Ulk2 significantly suppressed tumor volume in vivo (P<0.05). Overexpression of Ulk2 inhibits cancer cell proliferation and enhances chemosensitivity to cisplatin in NSCLC.

Overexpression of Long Non-Coding RNA ZXF2 Promotes Lung Adenocarcinoma Progression Through c-Myc Pathway.

OBJECTIVE: To investigate the expression of long non-coding RNA ZXF2 in lung adenocarcinoma tissues and its effect on cell proliferation, migration and invasion. METHODS: Forty pairs of cancerous and adjacent non-cancerous lung adenocarcinoma specimens were collected for the studies. Quantitative real-time PCR was used to analyze the expression of ZXF2 in tumor tissues and adjacent normal tissues. The expression of ZXF2 was correlated with patients' clinico-pathological data. Molecular pathway controlled by ZXF2 was explored by using small interfering RNA (siRNA) technology. CCK-8 cell proliferation assay, flow cytometry analysis and transwell assays were used to evaluate cell proliferation, migration and invasion. RESULTS: The expression of ZXF2 was 2 fold or higher in 27 out of 40 (67.5%) cases of lung adenocarcinoma specimens than that in non-cancerous tissues (P<0.05). The relative expression level of ZXF2 was positively correlated with tumor lymph node metastasis (χ(2)=8.485, P<0.05) and poor prognosis of the patients (p=0.0217). In order to explore the molecular mechanisms of ZXF2 mediated tumor progression, ZXF2 expression was inhibited by siRNA in A549 cells, a highly aggressive and metastatic lung adenocarcinoma cell line. We found that siRNA-ZXF2 treatment inhibited cell proliferation (P<0.01) leading to cell cycle arrest (P<0.01). The cell migration and invasion were suppressed by siRNA-ZXF2 treatment (P<0.01). Further biochemical studies revealed that the knockdown of ZXF2 led to down regulation of c-Myc signaling. CONCLUSION: ZXF2 was overexpressed in lung adenocarcinoma tissues and the high expression of ZXF was closely related to tumor progression through c-Myc related pathway. Given the fact that both ZXF2 and c-Myc are located in the same chromosome 8q24.2 loci, the potential interaction between ZXF2 and c-Myc might be a novel target for treatment of lung adenocarcinoma.