miR-106b-25/miR-17-92 clusters: Polycistrons with oncogenic roles in hepatocellular carcinoma

MicroRNAs are small endogenously expressed RNA molecules which are involved in the process of silencing gene expression through translational regulation. The polycistronic miR-17-92 cluster is the first microRNA cluster shown to play a role in tumorigenesis. It has two other paralogs in the human genome, the miR-106b-25 cluster and the miR-106a-363 cluster. Collectively, the microRNAs encoded by these clusters can be further grouped based on the seed sequences into four families, namely the miR-17, the miR-92, the miR-18 and the miR-19 families. Over-expression of the miR-106b-25 and miR-17-92 clusters has been reported not only during the development of cirrhosis but also subsequently during the development of hepatocellular carcinoma. Members of these clusters have also been shown to affect the replication of hepatitis B and hepatitis C viruses. Various targets of these microRNAs have been identified, and these targets are involved in tumor growth, cell survival and metastasis. In this review, we first describe the regulation of these clusters by c-Myc and E2F1, and how the members of these clusters in turn regulate E2F1 expression forming an auto-regulatory loop. In addition, the roles of the various members of the clusters in affecting relevant target gene expression in the pathogenesis of hepatocellular carcinoma will also be discussed.     

Temporal expression of microRNA cluster miR-17-92 regulates effector and memory CD8+ T-cell differentiation

MicroRNAs are important regulators of various developmental and physiological processes. However, their roles in the CD8(+) T-cell response are not well understood. Using an acute viral infection model, we show that microRNAs of the miR-17-92 cluster are strongly induced after T-cell activation, down-regulated after clonal expansion, and further silenced during memory development. miR-17-92 promotes cell-cycle progression of effector CD8(+) T cells, and its expression is critical to the rapid expansion of these cells. However, excessive miR-17-92 expression enhances mammalian target of rapamycin (mTOR) signaling and strongly skews the differentiation toward short-lived terminal effector cells. Failure to down-regulate miR-17-92 leads to a gradual loss of memory cells and defective central memory cell development. Therefore, our results reveal a temporal expression pattern of miR-17-92 by antigen-specific CD8(+) T cells during viral infection, the precise control of which is critical to the effector expansion and memory differentiation of CD8(+) T cells.     

血清miR-92a-1-5p及miR-92a-2-5p表达水平与老年卒中后抑郁的关系

目的 分析血清微小核糖核酸-92a-1-5p ( miR-92a-1-5p)、 miR-92a-2-5p 表达水平与老年卒中后抑郁的关系.方法 选取2018年2月至2020年10月胶州中心医院收治的129例老年卒中患者为研究组,另选取110名同期健康体检者为对照组,均检测血清miR-92a-1-5p、miR-92a-2...     

Hypermethylation of miRNA-17-92 cluster in peripheral blood mononuclear cells in diabetic retinopathy

Background and aimsDiabetic retinopathy (DR) is the most common complication of diabetes. The inflammatory milieu of diabetes results in changes throughout the body. This study asked whether epigenetic changes in peripheral blood mononuclear cells (PBMCs) reflect DR severity.MethodsPBMCs were separated from the whole blood of DR individuals using density gradient centrifugation. DNA was isolated, and methylation of micro-RNA (miR)-17–92 cluster was evaluated.ResultsWe observed that the miR-17–92 cluster was hypermethylated in DR individuals; specifically, this change was most remarkable with proliferative-DR (PDR).ConclusionsmiR-17–92 methylation in PBMCs could help understand DR's pathogenesis and identify individuals at the risk of severe DR for early intervention.     

Selection of benign primitive hematopoietic progenitors in chronic myelogenous leukemia on the basis of HLA-DR antigen expression.

Chronic myelogenous leukemia (CML) is a lethal malignancy of the human hematopoietic stem cell. Here we report that coexistent benign, primitive hematopoietic progenitors can be distinguished from their malignant counterparts in CML bone marrow by differences in cell surface antigen expression. Selection of bone marrow cells expressing the CD34 antigen but lacking the HLA-DR antigen results in recovery of small lymphocyte-like blasts, which initiate and sustain production of myeloid clonogenic progeny in vitro. Secondary clonogenic cells derived at week 1, 5, and 8 from long-term bone marrow cultures (LTBMCs) initiated with primitive progenitors, which lack HLA-DR antigens, exhibit neither the Philadelphia chromosome (Ph1) nor the corresponding bcr/abl mRNA characteristic of CML. In contrast, clonogenic cells recovered at week 1, 5, and 8 from LTBMCs initiated with the CML HLA-DR+ population contain Ph1 and express bcr/abl mRNA. This observation indicates that it may be possible to select a population of viable, exclusively benign hematopoietic stem cells from CML bone marrow capable of repopulating the hematopoietic compartment following autologous bone marrow transplantation.     

MicroRNA-17-92 down-regulates expression of distinct targets in different B-cell lymphoma subtypes

Aberrant overexpression of the miR-17-92 polycistron is strongly associated with B-cell lymphomagenesis. Recent studies have shown that miR-17-92 down-regulates the proapoptotic protein Bim, leading to overexpression of Bcl2, which likely plays a key role in lymphomagenesis. However, the fact that Jeko-1 cells derived from mantle cell lymphoma exhibit both homozygous deletion of BIM and overexpression of miR-17-92 suggests other targets are also involved in B-cell lymphomagenesis. To identify essential target(s) of miR-17-92 in lymphomagenesis, we first transfected miR-17-92 into 2 genetically distinct B-cell lymphoma cell lines: Raji, which overexpress c-Myc, and SUDHL4, which overexpress Bcl2. Raji transfected with miR-17-19b-1 exhibited down-regulated expression of Bim and a slight up-regulation in Bcl2 expression. On the other hand, SUDHL4 transfectants showed aggressive cell growth reflecting facilitated cell cycle progression at the G(1) to S transition and decreased expression of CDKN1A mRNA and p21 protein (CDKN1A/p21) that was independent of p53 expression. Conversely, transfection of antisense oligonucleotides against miR-17 and miR-20a into Jeko-1 led to up-regulation of CDKN1A/p21, resulting in decreased cell growth with G(1) to S arrest. Thus, CDKN1A/p21 appears to be an essential target of miR-17-92 during B-cell lymphomagenesis, which suggests the miR-17-92 polycistron has distinct targets in different B-cell lymphoma subtypes.     

miR-221-3p在下肢缺血性疾病中的表达变化

目的探讨miR-221-3p在下肢缺血性疾病中的表达变化。方法临床试验:收集西南医科大学附属医院血管甲状腺外科2014年至2015年间55例动脉硬化闭塞症(ASO)患者和54例健康对照人群血浆,24例ASO截肢患者的正常血管及病变血管。选取3对年龄、性别相近的ASO患者和正常健康人血浆用Microarray筛选出ASO患者血浆中差异性表达在2倍以上的24种microRNA,其中miR-221-3p的表达量明显降低。用实时荧光定量PCR检测临床55例ASO患者和54例健康对照人群血浆及24例ASO截肢患者正常血管和病变血管中miR-221-3p的表达量。动物实验:选取SD大鼠,结扎组分离结扎大鼠股动脉制备下肢缺血模型,假手术组仅暴露分离股动脉不做结扎。分别于术前、术后即刻、术后7天、49天行激光多普勒扫描监测下肢皮肤血流变化。于术后7天、49天行激光多普勒扫描后处死各组大鼠,收集大鼠术侧腓肠肌及下腔静脉血,采用实时荧光定量PCR检测各组血浆和腓肠肌内miR-221-3p的表达量。结果临床试验显示:与健康对照组相比,ASO患者血浆中miR-22-3p的含量明显降低(1.078±0.119比0.617±0.121);与正常血管相比,病变血管中miR-221-3p的表达量也明显降低(1.017±0.113比0.625±0.136)。动物实验显示:与假手术组相比,结扎组7天时血浆和腓肠肌内miR-221-3p的含量明显降低(血浆1.04±0.07比0.31±0.07、腓肠肌1.01±0.07比0.64±0.09),49天时miR-221-3p的含量有所上升但仍低于对照组。结论 miR-221-3p在下肢缺血性疾病中明显降低,有望成为下肢缺血性疾病一个新的诊断方式及治疗靶点。     

Forced expression of p21 in GPIIb-p21 transgenic mice induces abnormalities in the proliferation of erythroid and megakaryocyte progenitors and primitive hematopoietic cells

OBJECTIVE: p21(WAF1/Cip/kip) and p27(Kip1) are cyclin-dependant kinase inhibitors controlling cell-cycle exit and differentiation of numerous cell types. Among hematopoietic cells, megakaryocytes express high levels of p21, while in erythroid cells, p27(Kip1) is predominant. As p21 and p27 could display overlapping functions and as megakaryocytes and erythroid cells derive from a bipotent progenitor, we developed an in vivo model to determine the specific role of p21 in controlling the proliferation/differentiation balance of erythroid and megakaryocytic progenitors. METHODS: Transgenic mice that overexpressed p21 under the control of the human GPIIb promoter in early progenitors and along megakaryocytic differentiation were generated. Different subsets of hematopoietic progenitors (BFU and CFU) and primitive cells (CAFC, LTC-IC) were analyzed by methylcellulose assay. Phenotypic evolution and clonogenic properties of the lin(-) population were analyzed along erythroid and megakaryocytic differentiation. RESULTS: We observed p21 ectopic expression in early hematopoietic progenitors (lin(-)Sca(+)), megakaryocytes, and, to a lesser extent, erythroid cells. This expression induced an important decrease in the number of CFU-MK, BFU-E, CFU-E, primitive progenitors (CAFC day 35), and LTC-IC, but did not affect the maturation process of these cells and the blood cell count. CONCLUSIONS: We show that variation of p21 expression level changes the fate of hematopoietic cells by favoring either proliferation or differentiation pathways. This effect of p21 is exerted not only at the level of primitive progenitors but also in more mature progenitors. However, in vivo, a systemic compensation mechanism is most likely activated in response to variations of the flow of progenitor production.     

白血病患者造血细胞磷酸酶与半胱氨酸蛋白酶基因表达及其临床意义

目的探讨造血细胞磷酸酶（SHP-1）基因和天冬酰胺特异酶切的半胱氨酸蛋白酶（Caspase-1、3）基因表达与白血病患者的化疗效果的关系。方法用RT-PCR方法检测白血病患者骨髓单个核细胞中SHP-1和Caspase-1、3的mRNA表达。结果急性白血病（AL）患者SHP-1和Caspase-1、3表达率分别为33．3％、80．0％、100．0％;慢性髓细胞白血病（CML）患者SHP-1表达率在急变期、慢性期分别为0．0％、37．5％。SHP-1和Caspase-1、3基因阳性患者的首次完全缓解（CR）率分别为85．0％、64．3％、55．8％,明显高于阴性患者（分别为15．6％、20．0％）,差异均有统计学意义（P〈0．05）;Caspase-1、3与SHP-1表达呈正相关。结论SHP-1可能是一个潜在的抑癌基因,它可能是通过激活下游的凋亡基因Caspase-1、3发挥作用;Caspase-1、3与SHP-1基因表达呈正相关且与病人的CR率有关,表明它们均参与了白血病的转归,可同时作为判断白血病患者的疗效和预后指标。     

超声内镜细针穿刺研究胰腺组织中微小核糖核酸的表达及临床意义

目的 研究超声内镜(EUS)-细针穿刺(FNA)胰腺组织中微小核糖核酸(miRNA)的表达及临床意义.方法 用实时定量逆转录-聚合酶链反应方法 检测23例胰腺癌和13例胰腺良性占位病变的EUS-FNA组织标本中miRNA-210、miRNA-21、miRNA-196a、miRNA-181a、miRNA-181b、miRNA-155和miRNA-16的表达并分析其临床意义.结果 胰腺癌中miRNA-210、miRNA-21、miRNA-196a、miRNA-181a、miRNA-181b的相对表达量分别为0.86±1.10、0.69±0.64、0.32±2.50、0.16±0.83、0.56±0.88,均较胰腺良性占位病变中(分别为-0.11±0.98、-0.03±0.97、-1.50±1.40、-0.53±1.10、-0.28±1.10)显著升高,P值分别=0.012、0.011、0.024、0.036、0.015.miRNA-16、miRNA-155在胰腺癌组织和胰腺良性占位病变中的相对表达量分别为-0.11±0.69、0.08±1.04和-0.73±1.26、-0.19±1.19,差异均无统计学意义(P值分别=0.067和0.467).miRNA-196a高表达与胰腺癌淋巴结转移和TNM分期正相关.结论 胰腺癌发生中存在多条miRNA异常高表达,其中miRNA-196a与胰腺癌临床恶性特征相关.