Down-regulation of microRNA-34a* in rheumatoid arthritis synovial fibroblasts promotes apoptosis resistance
ABSTRACT To investigate the expression and effect of the microRNA-34 (miR-34) family on apoptosis in rheumatoid arthritis synovial fibroblasts (RASFs).
Expression of the miR-34 family in synovial fibroblasts with or without stimulation with Toll-like receptor (TLR) ligands, tumor necrosis factor α (TNFα), interleukin-1β (IL-1β), hypoxia, or 5-azacytidine was analyzed by real-time polymerase chain reaction (PCR). Promoter methylation was studied by combined bisulfite restriction analysis. The effects of overexpression and silencing of miR-34a and miR-34a* on apoptosis were analyzed by annexin V/propidium iodide staining. Production of X-linked inhibitor of apoptosis protein (XIAP) was assessed by real-time PCR and immunohistochemistry analysis. Reporter gene assay was used to study the signaling pathways of miR-34a*.
Basal expression levels of miR-34a* were found to be reduced in synovial fibroblasts from RA patients compared to osteoarthritis patients, whereas levels of miR-34a, miR-34b/b*, and miR-34c/c* did not differ. Neither TNFα, IL-1β, TLR ligands, nor hypoxia altered miR-34a* expression. However, we demonstrated that the promoter of miR-34a/34a* was methylated and showed that transcription of the miR-34a duplex was induced upon treatment with demethylating agents. Enforced expression of miR-34a* led to an increased rate of FasL- and TRAIL-mediated apoptosis in RASFs. Moreover, levels of miR-34a* were highly correlated with expression of XIAP, which was found to be up-regulated in RA synovial cells. Finally, we identified XIAP as a direct target of miR-34a*.
Our data provide evidence of a methylation-specific down-regulation of proapoptotic miR-34a* in RASFs. Decreased expression of miR- 34a* results in up-regulation of its direct target XIAP, thereby contributing to resistance of RASFs to apoptosis.
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ABSTRACT: Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovitis, synovial hyperplasia and progressive degeneration of affected joints. These processes are mediated by cells of the immune system as well as by synovial fibroblasts (RASF) originating from the lining layer of the synovium. In this scenario RASFs display an activated phenotype: they show an altered expression of adhesion molecules which allows attachment to articular cartilage and by synthesis of proteases they mediate progressive cartilage and bone destruction. Furthermore, they produce various cytokines and chemokines, which are essential for promoting the inflammatory response. In recent years it has become evident that RASFs not only passively respond to the proinflammatory milieu in the joints of RA patients but also actively contribute by the overproduction of several cytokines and chemokines. These proinflammatory cytokines trigger the transformation of RASFs into an aggressive and invasive phenotype. Additionally, the primarily altered genuine RASFs are actively involved in the recruitment and activation of immune cells. Taken together, they are key players in the development of the well-known chronic, destructive inflammatory response in joints affected by RA.
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ABSTRACT: MiR-200c expression is dysregulated in various malignancies and may predict the survival of patients with cancer, although the results of different studies conflict. Therefore, we conducted a meta-analysis to resolve this discrepancy. We queried the PubMed and Embase using multiple search strategies. Data were extracted from studies comparing overall survival and progression-free survival in patients with cancer with high and low levels of miR-200c expression. Fixed and random models were used where appropriate. A combined hazards ratio (HR) was calculated to estimate the association of high levels of miR-200c with survival. We selected 16 studies of 1485 participants for our final meta-analysis. Upregulated expression of miR-200c predicted significantly worse overall survival in patients with cancer (HR 1.51; 95% confidence interval [CI] 1.06-2.16, P = 0.023). Subgroup analysis indicated that high levels of miR-200c was associated with decreased survival of Caucasians and patients with gynecological tumors with pooled HR values of 1.82 (95% CI 1.27-2.26, P = 0.01) and 3.23 (95% CI 1.11-9.38, P = 0.032), respectively. Because of the absence of apparent heterogeneity, the combined HRs were 1.69 (95% CI 1.24-2.30, P = 0.001) for squamous cell carcinoma and 1.91 (95% CI 1.40-2.59, P < 0.001) for samples from peripheral blood. Increased expression of miR-200c significantly associated with shorter progression-free survival of patients with cancer (HR 2.37; 95% CI 1.47-3.81, P < 0.001). Our meta-analysis indicates that the level of miR-200c expression predicted survival of patients with cancer, particularly for Caucasians and patients with gynecological cancer. Increased expression of miR-200c predicted shorter survival of patients with squamous cell carcinomas. Our findings indicate that monitoring the levels of miR-200c in blood may be useful for following tumor progression as well as patients' prognosis.International Journal of Clinical and Experimental Medicine 01/2015; 8(2):1931-43. · 1.42 Impact Factor
Article: MicroRNAs in rheumatoid arthritis[Show abstract] [Hide abstract]
ABSTRACT: The role of genetic and epigenetic factors in the development of rheumatic diseases has been an interesting field of research over the past decades all around the world. Research on the role of microRNAs (miRNAs) in rheumatoid arthritis (RA) has been active and ongoing, and investigations have attempted to use miRNAs as biomarkers in disease diagnosis, prognosis, and treatment. This review focuses on experimental researches in the field of miRNAs and RA to present the data available up to this date and includes researches searched by keywords "microRNA" and "rheumatoid arthritis" in PubMed from 2008 to January 2015. All references were also searched for related papers. miRNAs are shown to act as proinflammatory or anti-inflammatory agents in diverse cell types, and their role seems to be regulatory in most instances. Researchers have evaluated miRNAs in patients compared to controls or have investigated their role by overexpressing or silencing them. Multiple targets have been identified in vivo, in vitro, or in silico, and the researches still continue to show their efficacy in clinical settings.Clinical Rheumatology 03/2015; 34(4). DOI:10.1007/s10067-015-2898-x · 1.77 Impact Factor