MiRNA-181b suppresses IGF-1R and functions as a tumor suppressor gene in gliomas

MicroRNAs (miRNAs) are single-stranded, 18- to 23-nt RNA molecules that function as regulators of gene expression. Previous studies have shown that microRNAs play important roles in human cancers, including gliomas. Here, we found that expression levels of miR-181b were decreased in gliomas, and we identified IGF-1R as a novel direct target of miR-181b. MiR-181b overexpression inhibited cell proliferation, migration, invasion, and tumorigenesis by targeting IGF-1R and its downstream signaling pathways, PI3K/AKT and MAPK/ERK1/2. Overexpression of IGF-1R rescued the inhibitory effects of miR-181b. In clinical specimens, IGF-1R was overexpressed, and its protein levels were inversely correlated with miR-181b expression. Taken together, our results indicate that miR-181b functions in gliomas to suppress growth by targeting the IGF-1R oncogene and that miR-181b may serve as a novel therapeutic target for gliomas.     

The microRNA-302-367 cluster suppresses the proliferation of cervical carcinoma cells through the novel target AKT1

The miR-302-367 cluster is specifically expressed in human embryonic stem cells and has been shown to convert human somatic cells into induced pluripotent stem cells. Here, we investigated the role of the miR-302-367 cluster in cervical carcinoma. The cluster was not endogenously expressed in cervical cancer cells, and its ectopic expression did not reprogram the cervical cancer cells to an embryonic stem cell-like state. However, ectopic expression of the miR-302-367 cluster in HeLa and SiHa cervical cancer cells inhibited cell proliferation and tumor formation by blocking the G1/S cell cycle transition. We identified a new cell cycle regulatory pathway in which the miR-302-367 cluster directly down-regulated both cyclin D1 and AKT1 and indirectly up-regulated p27^Kip1 and p21^Cip1, leading to the suppression of cervical cancer cell proliferation. Our findings suggest that the miR-302-367 cluster may be used as a therapeutic reagent for the treatment of cervical carcinoma.     

Isolation of Synaptic Complexes in a CsCl Gradient: Conditions for Maximal Resolution in the Zonal Rotor B-Xiv and Circular Dichroism Patterns

Synaptic complexes were isolated from different brain regions and developmental stages in a CsCl density gradient using a Ti-14 zonal rotor. The buoyant density of the synaptic complexes from all these tissues was 1.178–1.190. The conditions for maximal resolution were rapid displacement of the density gradient from the rotor (40 ml/min); continuous centrifugation of the particles in the gradient for 66 hours, sample loads not exceeding 200 mg membrane protein. The banding densities of the membranes in the CsCl gradient were shown to be a linear inverse function of their lipid content. The circular dichroism patterns of synaptic complexes and other neural membranes in suspension or SDS solutions were similar to those of membranes from other mammalian cells or from bacteria although the ellipticities of the neural membranes were lower. These studies indicate that the proteins in a variety of membranes are in an α-helical conformation.     

DGCR8‐mediated disruption of miRNA biogenesis induces cellular senescence in primary fibroblasts

The regulation of gene expression by microRNAs (miRNAs) is critical for normal development and physiology. Conversely, miRNA function is frequently impaired in cancer, and other pathologies, either by aberrant expression of individual miRNAs or dysregulation of miRNA synthesis. Here, we have investigated the impact of global disruption of miRNA biogenesis in primary fibroblasts of human or murine origin, through the knockdown of DGCR8, an essential mediator of the synthesis of canonical miRNAs. We find that the inactivation of DGCR8 in these cells results in a dramatic antiproliferative response, with the acquisition of a senescent phenotype. Senescence triggered by DGCR8 loss is accompanied by the upregulation of the cell‐cycle inhibitor p21CIP1. We further show that a subset of senescence‐associated miRNAs with the potential to target p21CIP1 is downregulated during DGCR8‐mediated senescence. Interestingly, the antiproliferative response to miRNA biogenesis disruption is retained in human tumor cells, irrespective of p53 status. In summary, our results show that defective synthesis of canonical microRNAs results in cell‐cycle arrest and cellular senescence in primary fibroblasts mediated by specific miRNAs, and thus identify global miRNA disruption as a novel senescence trigger.     

HCV-specific interleukin-21+CD4+ T cells responses associated with viral control through the modulation of HCV-specific CD8+ T cells function in chronic hepatitis C patients

Interleukin-21 (IL-21)+CD4+ T cells are involved in the immune response against hepatitis B virus (HBV) by secreting IL-21. However, the role of IL-21+CD4+ T cells in the immune response against chronic hepatitis C (CHC) virus infection is poorly understood. This study aimed to investigate the role of IL-21+CD4+ T cells in CHC patients and the potential mechanisms. The study subjects included nineteen CHC patients who were grouped by viral load (low, < 10⁶ RNA copies/ml, n = 8; high, > 10⁶ RNA copies/ml, n = 11). The peripheral frequency of HCV-specific IL-21+CD4+ T cells was higher in the low viral load group and was negatively correlated with the serum HCV RNA viral load in all CHC patients. Meanwhile, IL-21+ cells accumulated in the liver in the low viral load group. In vitro, IL-21 treatment increased the expression of proliferation markers and cytolytic molecules on HCV-specific CD8+ T cells. In summary, these findings suggest that HCV-specific IL-21+CD4+ T cells might contribute to HCV control by rescuing HCV-specific CD8+ T cells in CHC patients.     

Circulating microRNAs have a sex-specific association with metabolic syndrome

Background

The microRNAs let-7 g and miR-221 have been demonstrated to be related to the glucose metabolism. This study assessed the serum levels of these two microRNAs in subjects with and without metabolic syndrome (MetS).

Results

The serum microRNA levels were detected in 102 subjects aged 40 to 80 years who were recruited from the general population. The status of MetS was defined by the Adult Treatment Panel III (ATP III) criteria modified for Asians. Subjects with histories of cardiovascular diseases or who were receiving treatment with hypoglycemic or lipid-lowering agents were excluded. The levels of both circulating microRNAs (let-7 g and miR-221) were higher in subjects with MetS (p = 0.004 and p = 0.01, respectively). The sex-specific analysis showed that the difference was more prominent in women (for both miRNAs, p < 0.05 in women and p > 0.1 in men). In the female subjects, increased expression of both microRNAs was associated with an increased number of MetS risk components (p = 0.002 for let-7 g and p = 0.022 for miR-221). Moreover, the elevation of serum let-7 g was significantly associated with a low level of high-density lipoprotein cholesterol (p = 0.022) and high blood pressure (p = 0.023). In contrast, the miR-221 level was not associated with any individual MetS risk component.

Conclusions

The circulating levels of let-7 g and miR-221 displayed a female-specific elevation in individuals with metabolic syndrome.     

Circulating miRNA-33: a potential biomarker in patients with coronary artery disease

Background: Circulating microRNAs (miRNA) are present in body fluids in stable, cell-free form. Likewise, these miRNAs can be identified in various stages of coronary artery disease (CAD) such as inflammation, endothelial dysfunction, proliferation and atherosclerosis among others. miRNA expression levels can be identified.

Aims and objectives: To determine the expression of circulating miRNAs (miR-126, miR-92, miR-33, miR-145 and miR-155) in CAD patients of Indian origin.

Material and methods: miRNA profiling analysis in blood plasma was performed by quantitative real-time-PCR (qRT-PCR) in 60 angiographically verified subjects including 30 CAD patients and 30 age- and gender-matched controls. Association between the expression of all five circulating miRNAs and clinical characteristics of patients with CAD were analysed using Medcalc statistics. The severity of CAD was assessed using SYNTAX score (SS).

Results: Expression of plasma miR-33 increased by 2.9 folds in CAD patients than in control group (p value ≥0.002) also it was found that miR-33 expression levels in mild cases (SS: ≤22) were significantly higher than CAD controls. There was a modest negative correlation between miR-33 and total cholesterol/high density lipoprotein ratio, triglycerides and very low density lipoprotein.

Conclusion: The study reports a significant association between increased levels of plasma miR-33 and CAD. Thus, plasma miR-33 appears to be a promising non-invasive biomarker, but requires further validation in a large cohort.     

MicroRNA-21与平滑肌蛋白22α在哈萨克族食管癌组织中的表达及其临床病理学意义

目的探讨microRNA21与SM22a基因在哈萨克族食管癌发生发展中的作用及临床意义。方法免疫组织化学法检测162例石蜡包埋食管鳞状细胞癌组织及RT-PCR方法检测47例哈萨克族食管癌标本中microRNA21、SM22a表达水平,分析这些基因与临床病理特征的关系。结果SM22a在162例食管鳞癌组织中的阳性表达率(87.0%)显著高于食管正常黏膜组织(36.0%);在47例哈萨克族食管癌组织中,SM22a表达水平较远端无癌组织增高。与远端无癌组织相比,microRNA21在哈萨克族食管癌组织中表达水平增高。MicroRNA21高表达与分化程度、淋巴结转移、临床分期相关,SM22a高表达与临床分期相关、淋巴结转移相关;microRNA21与SM22a的表达呈正相关。结论MicroRNA21、SM22a协同高表达共同参与哈萨克族食管癌的侵袭发展过程。