Effect of miR-24 on chemotherapy sensitivity in lung cancer A549 cells / 中国病理生理杂志

AIM:To study the effect of microRNA (miR)-24 on chemotherapy sensitivity and its possible mechanisms in human lung adenocarcinoma A549 cells. METHODS:The expression of miR-24 in the A549 cells and A549/DDP cells was determined by real-time PCR. Transfection of miR-24 inhibitor was used to down-regulate the miR-24 level in the A549/DDP cells. The viability and apoptosis rate were measured by CCK-8 assay and flow cytometry, respec-tively. The protein levels of Bcl-2, Bax, cleaved caspase-3, cleaved caspase-9, cytochrome C (Cyt C), phosphorylated extracellular signal regulated kinase (p-ERK) and P53 were detected by Western blot. Luciferase reporter assay was used to predict and identify the target genes of miR-24. RESULTS:The expression of miR-24 was significantly higher in the A549/DDP cells than that in the A549 cells (P<0.05). miR-24 inhibitor induced cell apoptosis and increased the sensi-tivity of the A549/DDP cells to cisplatin. Furthermore, miR-24 inhibitor down-regulated the ratio of Bcl-2/Bax, while up-regulated the protein levels of P53, p-ERK, cleaved caspase-9, cleaved caspase-3 and Cyt C. Incubation with U0126, a specific ERK inhibitor, partly reversed the viability of miR-24 inhibitor transfected A549/DDP cells. Bioinformatics analy-sis demonstrated that p53 was a potential target gene of miR-24. Co-teansfection of miR-24 inhibitor and P53 siRNA in A549/DDP cells partially reversed the effect of miR-24 inhibitor on cell viabiltiy. CONCLUSION:Down-regulation of miR-24 increases the sensitivity of A549/DDP cells to cisplatin. The mechanism may be related to directly targeting p53 gene and over-activation of ERK/P53 signaling pathway, thus promoting apoptosis via mitochondrial apoptosis pathway.

Cardiac Hypertrophy is Positively Regulated by MicroRNA‑24 in Rats / 中华医学杂志(英文版)

<p><b>Background</b>MicroRNA-24 (miR-24) plays an important role in heart failure by reducing the efficiency of myocardial excitation-contraction coupling. Prolonged cardiac hypertrophy may lead to heart failure, but little is known about the role of miR-24 in cardiac hypertrophy. This study aimed to preliminarily investigate the function of miR-24 and its mechanisms in cardiac hypertrophy.</p><p><b>Methods</b>Twelve Sprague-Dawley rats with a body weight of 50 ± 5 g were recruited and randomly divided into two groups: a transverse aortic constriction (TAC) group and a sham surgery group. Hypertrophy index was measured and calculated by echocardiography and hematoxylin and eosin staining. TargetScans algorithm-based prediction was used to search for the targets of miR-24, which was subsequently confirmed by a real-time polymerase chain reaction and luciferase assay. Immunofluorescence labeling was used to measure the cell surface area, and H-leucine incorporation was used to detect the synthesis of total protein in neonatal rat cardiac myocytes (NRCMs) with the overexpression of miR-24. In addition, flow cytometry was performed to observe the alteration in the cell cycle. Statistical analysis was carried out with GraphPad Prism v5.0 and SPSS 19.0. A two-sided P < 0.05 was considered as the threshold for significance.</p><p><b>Results</b>The expression of miR-24 was abnormally increased in TAC rat cardiac tissue (t = -2.938, P < 0.05). TargetScans algorithm-based prediction demonstrated that CDKN1B (p27, Kip1), a cell cycle regulator, was a putative target of miR-24, and was confirmed by luciferase assay. The expression of p27 was decreased in TAC rat cardiac tissue (t = 2.896, P < 0.05). The overexpression of miR-24 in NRCMs led to the decreased expression of p27 (t = 4.400, P < 0.01), and decreased G0/G1 arrest in cell cycle and cardiomyocyte hypertrophy.</p><p><b>Conclusion</b>MiR-24 promotes cardiac hypertrophy partly by affecting the cell cycle through down-regulation of p27 expression.</p>

Effect and mechanism of microRNA-24 on cell proliferation and migration of osteosarcoma cell line U2OS / 国际肿瘤学杂志

Objective To investigate the effect of microRNA-24 (miR-24) on cell proliferation and migration in osteosarcoma cell line U2OS and its possible mechanism.Methods U2OS cell line with miR-24 over-expression was established by transfecting miR-24 mimic, and then cell proliferation and migration in control group, negative control group and miR-24 over-expression group were detected with real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) assay, cell counting kit-8 (CCK-8) assay and Transwell assay, respectively.Epithelial-mesenchymal transition (EMT) progression and activation of nuclear factor-κB (NF-κB) pathway were detected by Western blotting.Results The expressions of miR-24 in the control group, negative control group and miR-24 over-expression group were 1.00±0.00, 1.03±0.08 and 2.46±0.29, with significant difference (F=11.026, P=0.012).Compared with the control group, the expression of miR-24 in human osteosarcoma U2OS cell line was significantly increased after transfecting miR-24 mimic (t=4.604, P=0.009).After over-expression of miR-24 for 24 h, 48 h and 72 h, U2OS cell viabilities were decreased significantly compared with the control group [(3.56±0.27)% vs.(8.63±0.79)%, t=3.896, P=0.016;(20.16±1.09)% vs.(54.77±5.42)%, t=4.813, P=0.008;(45.47±3.16)% vs.(95.52±8.56)%, t=7.173, P=0.002)].After over-expression of miR-24 for 24 h, the cell migration rates in control group, negative control group and miR-24 over-expression group were (100.00±0.00)%, (99.26±5.85)% and (31.37±2.09)%, respectively, and there was statistically significant difference among the three groups (F=12.175, P=0.009);and compared with control group, cell migration rate was decreased significantly after over-expression of miR-24 (t=3.843, P=0.004).Meanwhile, over-expression of miR-24 up-regulated the expression levels of epithelial cell markers E-cadherin (t=3.852, P=0.018) and β-catenin (t=3.512, P=0.024), while down-regulated the expression levels of mesenchymal cell markers N-cadherin (t=3.832, P=0.018) and vimentin (t=4.058, P=0.012), with a suppressed EMT progress.Other than that, miR-24 over-expression inhibited the expressions of NF-κB (p65) (t=4.813, P=0.008), phosphorylation inhibitor of nuclear factor kappa-B kinase α (p-IKK-α) (t=3.764, P=0.013) and phosphorylation inhibitor of nuclear factor kappa-B kinase complex α (p-IκB-α) (t=4.064, P=0.012), suppressing the activation of NF-κB pathway.Conclusion miR-24 can suppress cell proliferation and migration of osteosarcoma cell line U2OS in vitro, and its mechanism may be related to the suppression of NF-κB activation and EMT progression.It hints that miR-24 may be used as a potential new target for osteosarcoma therapy.

Expression differences and clinical significance of miR-29b,miR-24 and miR-200c in plasma of infants with PCG and normal / 眼科新进展

Objective To identify the expression differences of mircoRNA-29 b (miR-29b),microRNA? 24 (miR-24) and microRNA-200 c (miR-200c) in plasma of infants with primary congenital glaucoma (PCG) and normal,and analyze its clinical significance.Methods The expression quantity of microRNAs (miR-29b,miR-24,miR-200c) in plasma of PCG group (16 cases) and normal control group (49 cases) were detected by RT-PCR,and the relationship between their expression differences and severity of disease were analyzed.The diagnostic value of miRNAs for PCG was evaluated by receiver-operating characteristic curve (ROC).Results The expression quantity of miR-29b,miR-24,miR-200c in PCG group (0.31 ±0.19,0.17 ±0.16,0.55 ±0.18,respectively) were significantly lower than those in normal control group (1.18-±0.52,2.86 ±2.65,1.62 ± 0.76,respectively) (all P ＜ 0.05);The expression quantity of miR-24 and miR-29b in plasma was related to the severity of PCG,the more severe the disease,the lower the expression;ROC curve indicated that miR-24 and miR-29b had a higher diagnostic value for PCG disease than miR-200c.Conclusion Free miRNAs in plasma may be used as a new plasma markers for auxiliary diagnosis of PCG.