Unicondylar knee replacement versus total knee replacement for the treatment of medial knee osteoarthritis: a systematic review and meta-analysis.

BACKGROUND: Since the optimal surgery for isolated medial knee osteoarthritis (OA) is unclear, this study aimed at comparing the effectiveness of unicondylar knee replacement (UKR) with total knee replacement (TKR) for simple medial knee OA. METHODS: Literature searches of PubMed, Embase, Web of Science, and the Cochrane Library were searched up to 1th April 2020. Only studies comparing UKR with TKR for isolated medial knee OA were included. Data collection and extraction, quality assessment, and data analyses were performed according to the Cochrane standards. RESULTS: A total of 13 articles with 1888 patients were included, among which, 944 and 944 underwent UKR and TKR, respectively. The analyzed postoperative outcomes were mostly within 5 years of follow-up. The meta-analysis showed that UKR improved knee general function (P < 0.00001) and health (P = 0.02), moreover, reduced post-operative pain (P = 0.01) and complications (P < 0.05) more than TKR. There were no significant differences in postoperative revision (P = 0.252), high-activity arthroplasty score (HAAS) (P = 0.307) and Oxford knee score (OKS) (P = 0.15) between the two techniques. CONCLUSIONS: The patients of UKR could achieve better clinical results than that of TKR, moreover, there were negligible differences between the two techniques in postoperative revision in the early and mid-term follow-up and surgeons should be aware of the important reasons for revision of UKR. Thus, UKR instead of TKR should be performed in patients with late-stage isolated medial knee OA.

A regulatory circuit comprising GATA1/2 switch and microRNA-27a/24 promotes erythropoiesis.

Transcriptional networks orchestrate complex developmental processes, and such networks are commonly instigated by master regulators for development. By now, considerable progress has been made in elucidating GATA factor-dependent genetic networks that control red blood cell development. Here we reported that GATA-1 and GATA-2 co-regulated the expression of two microRNA genes, microRNA-27a and microRNA-24, with critical roles in regulating erythroid differentiation. In general, GATA-2 occupied the miR-27a≈24 promoter and repressed their transcription in immature erythroid progenitor cells. As erythropoiesis proceeded, GATA-1 directly activated miR-27a≈24 transcription, and this involved a GATA-1-mediated displacement of GATA-2 from chromatin, a process termed 'GATA switch'. Furthermore, the mature miR-27a and miR-24 cooperatively inhibited GATA-2 translation and favoured the occupancy switch from GATA-2 to GATA-1, thus completing a positive feedback loop to promote erythroid maturation. In line with the essential role of GATA factors, ectopic expression of miR-27a or miR-24 promoted erythropoiesis in human primary CD34+ haematopoietic progenitor cells and mice, whereas attenuated miR-27 or miR-24 level led to impaired erythroid phenotypes in haematopoietic progenitor cells and zebrafish. Taken together, these data integrated micro RNA expression and function into GATA factor coordinated networks and provided mechanistic insight into a regulatory circuit that comprised GATA1/2 switch and miR-27a/24 in erythropoiesis.

miR-124 functions as a tumor suppressor in the endometrial carcinoma cell line HEC-1B partly by suppressing STAT3.

MicroRNAs (miRNAs) play an important role in the development and progression of endometrial carcinoma (EC). Recently, several studies have shown that microRNA-124 (miR-124) is downregulated in various cancers, which can affect tumor initiation and maintenance. However, the effects of miR-124 on EC are largely unknown. In this study, we identified the under-expression of miR-124 in 35 paired EC tissues and adjacent normal tissues. Further, functional experiments found that ectopic expression of miR-124 markedly suppressed cell proliferation, migration, and invasion of EC cells. It also induced cell apoptosis and G1-phase cell cycle arrest. Moreover, we identified signal transducer and activator of transcription 3 (STAT3) as a direct target of miR-124, and over expression of miR-124 not only induced changes in STAT3 expression but also altered expression of its target genes, cyclin D2 and matrix metalloproteinase 2, in the human endometrial carcinoma cell line HEC-1B. In addition to targeting STAT3 directly, we found that miR-124 suppresses phosphorylation of STAT3 through targeting IL-6R indirectly. Restored STAT3 expression through treatment with IL-6 cytokine partly abolished miR-124-mediated cell cycle arrest and apoptosis induction. These results combined with the tumorigenetic role of STAT3 in HEC-1B cells suggest that the antitumor effects of miR-124 are achieved, at least partly, through down regulation of STAT3 mRNA and its downstream target genes. Therefore, inhibition of constitutively activated STAT3 by ectopic expression of miR-124 in EC may provide a novel therapeutic strategy for the treatment of EC.

LIM mineralization protein-1 inhibits the malignant phenotypes of human osteosarcoma cells.

Osteosarcoma (OS), also known as osteogenic sarcoma, is the most common primary malignancy of bone tumor in children and adolescents. However, its underlying molecular pathogenesis is still only vaguely understood. Recently, LIM mineralization protein-1 (LMP-1) was reported to be an essential positive regulator of osteoblast differentiation. In the present study, we found that the expression of LMP-1 is downregulated in OS tissues compared with adjacent normal tissues. Moreover, we restored the expression of LMP-1 through a recombinant adenovirus. Overexpression of LMP-1 inhibited cell proliferation and invasion, arrested cell cycle progression, and induced apoptosis in vitro. Finally, ectopic LMP-1 expression suppressed the expression of Runx2 and BMP-2 in OS cells. These data demonstrate that LMP-1 is an essential tumor suppressor in the OS pathological process, which will provide a new opportunity for discovering and identifying novel effective treatment strategies.

Interplay between microRNAs and the STAT3 signaling pathway in human cancers.

MicroRNAs (miRNAs, also miR) are a class of noncoding endogenous RNAs that regulate gene expression through binding to protein-coding messenger RNA (mRNA) molecules, predominantly within the 3'-untranslated region (3'-UTR). Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that regulates a battery of genes involved in regulating a variety of biological processes. There is a growing body of evidence demonstrating that miRNAs are closely associated with the STAT3 signaling pathway. In this review, we focus on interactions between miRNAs and the STAT3 signaling pathway, focusing on their reciprocal regulation and roles in cancer. For instance, several papers independently support the existence of regulatory feedback loops between miRNAs and the STAT3 pathway in different cancer contexts including IL-6-STAT3-miR-24/miR-629-HNF4α-miR-124 and IL-6R-STAT3-NF-κB-Lin-28-let-7a. Furthermore, several miRNA components are reported to be involved in STAT3-mediated tumorigenesis, for example miR-21, miR-155, and miR-181b. Through binding to STAT3-binding sites within the promoters of these oncomiRs, STAT3 activates their transcription and mediates tumorigenesis. Some miRNAs directly modulate STAT3 activity through targeting the STAT3 3'-UTR; other miRNAs target SOCS, PIAS3, and EGFR genes, which encode proteins that regulate the STAT3 signaling pathway. Given that miRNAs represent a newly discovered class of regulatory molecules, investigating their biological functions and contribution to pathologies caused by STAT3 dysregulation is essential to improve our understanding of tumorigenesis and to develop novel anticancer therapeutics. The more we can learn about miRNAs-STAT3 interactions, the better able we will be to manipulate them for developing cancer therapeutics.

Multiple surgical treatment comparisons for irreparable rotator cuff tears: A network meta-analysis.

BACKGROUND: To evaluate the effect of different surgical methods in the treatment of patients with irreparable rotator cuff tears (IRCTs) using a network meta-analysis. METHODS: A search of the PubMed, EMbase, The Cochrane Library, VIP, WanFang Data, and CNKI databases was performed in January 2023 to search for randomized controlled trials and cohort studies of different surgical methods in the treatment of IRCTs. Risk assessment of the included randomized controlled trials was conducted using the risk of bias assessment tool recommended by the Cochrane Manual, and the Newcastle-Ottawa Scale was used for the risk assessment of cohort studies. Data were analyzed and plotted using Stata 15.0 software. RESULTS: A total of 17 studies involving 2123 patients and 10 surgical methods were included in this study. According to the surface under the cumulative ranking curve, the probability ranking in descending order is latissimus dorsi transfer (LDT) + partial repair > LDT > reverse total shoulder arthroplasty > superior capsular reconstruction > patch > partial repair > debridement + tenotomy of the long head of the biceps > debridement > in space subacromial balloon spacer + tenotomy of the long head of the biceps > in space subacromial balloon spacer. CONCLUSION: Among the multiple surgical treatments for patients with IRCTs, LDT + partial repair may have the best effect, and more randomized controlled trials with larger sample sizes are needed for further verification.

Let-7a suppresses Ewing sarcoma CSCs' malignant phenotype via forming a positive feedback circuit with STAT3 and lin28.

Cancer stem cells (CSCs) have been documented to be closely related with tumor metastasis and recurrence, and the same important role were identified in Ewing Sarcoma (ES). In our previous study, we found that let-7a expression was repressed in ES. Herein, we further identified its putative effects in the CSCs of ES (ES-CSCs). The expression of let-7a was consistently suppressed in the separated side population (SP) cells, which were identified to contain the characteristics of the stem cells. Then, we increased the expression of let-7a in ES-CSCs, and found that the ability of colony formation and invasion of ES-CSCs were suppressed in vitro. The same results were found in the tumor growth of ES-CSCs' xenograft mice in vivo. To further explore the putative mechanism involved, we also explored whether signal transducer and activator of transcription 3 (STAT3) was involved in the suppressive effects. As expected, excessive expression of let-7a could suppress the expression STAT3 in the ES-CSCs, and repressed the expression of STAT3 imitated the suppressive effects of let-7a on ES-CSCs, suppressing the ability of colony formation and invasion of ES-CSCs. Furthermore, we found lin28 was involved in the relative impacts of let-7a, as well as STAT3. Let-7a, STAT3 and lin28 might form a positive feedback circuit, which serve a pivotal role in the carcinogensis of ES-CSCs. These findings maybe provide assistance for patients with ES in the future, especially those with metastasis and recurrence, and new directions for their treatment.

Effects of 9 oral care solutions on the prevention of oral mucositis: a network meta-analysis of randomized controlled trials.

BACKGROUND: Oral mucositis (OM) is a common, disabling, and severe early effect of chemotherapy and radiotherapy that limits the effectiveness of anticancer therapy. The prevention and treatment of OM in patients with malignant tumors is an urgent problem in the field of anticancer therapy. METHODS: Databases including PubMed, Embase, Scopus, The Cochrane Library, and Google Scholar were searched to collect published randomized control trials (RCTs) about the effects of different oral care solutions on the prevention of OM from inception to January 2019. We used the Cochrane Handbook to assess the methodological quality of the RCTs. Two of the authors independently extracted the articles and predefined data. Network meta-analysis was then performed using Stata 15.0 software. RESULTS: A total of 28 RCTs involving 1861 patients were included. The results of network meta-analysis showed that chlorhexidine, benzydamine, honey, and curcumin were more effective than placebo (P < .05) and that honey and curcumin were more effective than povidone-iodine (P < .05). Probability ranking according to the Surface Under the Cumulative Ranking curve showed the following treatments: curcumin, honey, benzydamine, chlorhexidine, allopurinol, sucralfate, granulocyte-macrophage colony-stimulating factor, povidone-iodine, and aloe. CONCLUSION: Our preliminary results indicate that curcumin and honey may serve as the preferred options for patients to prevent OM. The findings may offer an important theoretical basis for clinical prevention and treatment. However, this conclusion still requires an RCT with a larger sample size for further verification.

MiR-107 suppresses cell proliferation and tube formation of Ewing sarcoma cells partly by targeting HIF-1ß.

MicroRNAs serve a crucial role in the regulation of malignant biological behavior of Ewing's sarcoma (ES). Abnormal expression of miR-107 has been reported in a cohort of cancers, while its exact function in ES remains unclear. Hence, we explored the expression of miR-107 in ES cells and detected its effects on the malignant phenotype of ES cells. Firstly, we perceived the under-expression of miR-107 in human ES cells contrast with the human mesenchymal stem cells. Over-expression of miR-107 restrained cell proliferation and tube formation, arrested cell cycle progression, and facilitated cell apoptosis in SK-ES-1 and RD-ES cell lines. Furthermore, hypoxia inducible factor-1ß (HIF-1ß) was assumed as a target gene of miR-107. We confirmed the target role of HIF-1ß in ES cells. Finally, restoring the expression of HIF-1ß could partly abolish miR-107-mediated tumor suppression in ES cells. In conclusion, our results advised that miR-107 suppressed the malignant biological ability of ES cells through targeting HIF-1ß.

miR­186 functions as a tumor suppressor in osteosarcoma cells by suppressing the malignant phenotype and aerobic glycolysis.

Osteosarcoma (OS) is the most common primary bone malignancy among children and adolescents. Deregulation of microRNAs has been well documented in OS, while the putative effects of miR­186 have not been identified yet. In the present study, we assessed the expression of miR­186 in a cohort of 40 OS tissues and explored its effects on OS cells. As expected, miR­186 was suppressed in OS tissues compared with relative normal tissues. Overexpression of miR­186 inhibited cell proliferation, arrested the cell cycle progression and suppressed the cell invasion of the HOS and U2 OS cell lines. These results indicated the tumor­suppressive role of miR­186 in OS. Among the target genes of miR­186, we found that pituitary tumor transforming gene 1 (PTTG1) may be a target gene of miR­186 in OS and that the overexpression of PTTG1 could partially abolish miR­186­mediated suppressive effects on OS cells. Aerobic glycolysis is the major way of energy supply and is one of the characteristic phenotypes of tumor cells. In addition, we found that overexpression of miR­186 significantly suppressed the expression of hypoxia­inducible factor 1 (HIF­1) and inhibited the glucose uptake and lactate production of OS cells. Collectively, our findings demonstrated that miR­186 functions as a tumor suppressor in OS cells partially by targeting PTTG1 and that HIF­1­mediated suppression of aerobic glycolysis may be also involved in its suppressive effects.

MicroRNA-638 inhibits cell growth and tubule formation by suppressing VEGFA expression in human Ewing sarcoma cells.

Ewing sarcoma (EWS) is a kind of aggressive tumor of bone and soft tissues, which most occurring in children and adolescents. MicroRNAs (miRNAs) perform essential function in the progression and development of EWS, while the putative role of miR-638 in EWS remains uncertain. Accordingly, we detected the expression of miR-638 and explored its putative biological effects on the malignant phenotype of EWS cells. As expected, miR-638 was significantly down-regulated in EWS cells. Moreover, overexpression of miR-638 suppressed cell growth, induced cell apoptosis, and inhibited tubule formation of EWS cells in vitro Among the putative target genes of miR-638 predicted by the miRNA target prediction tools, vascular endothelial cell growth factor A (VEGFA) attracted out attention most. The luciferase reporter assays reaffirmed that VEGFA was a targeted gene of miR-638 in EWS cells. Furthermore, miR-638 suppressed the mRNA and protein level of VEGFA, and restored the expression of VEGFA reversed the suppressed effects of miR-638 in EWS cells. Taken together, the results suggested that miR-638 might perform tumor suppressive effects in EWS, which might be mediated, at least partially, through suppressing the activity of VEGFA.

Chemotherapy-mediated miR-29b expression inhibits the invasion and angiogenesis of cervical cancer.

Radiotherapy combined with platinum-based chemotherapy is the standard-of-care of locally advanced cervical cancer (CC) patients, while nearly 50% of patients do not respond to standard chemotherapy. Thus, identification of relative molecules participated in chemotherapy might provide new insights in the treatment of CC. In this study, we found a cohort of miRNAs were dysregulated upon treatment with cisplatin, among of which miR-29b was the most upregulated one. We further detected its expression in CC tissues, and found that miR-29b was significantly suppressed in CC and its precancerous lesions, HSIL tissues, and was negatively related with tumor invasion. However, upon treatment with cisplatin, the expression of miR-29b was significantly up-regulated. The biological function assays showed that overexpression of miR-29b suppressed the invasion, EMT procedure and angiogenesis of cervical cancer cells in vitro and inhibited tumor growth and neovascularization in vivo through targeting STAT3 signal pathway. While, inhibition of miR-29b could prevent the cisplatin-induced epithelial features, cell movement and angiogenesis of CC cells, which means miR-29b/STAT3 axis participates in the chemotherapy of cisplatin in CC. Collectively, our data suggest that chemotherapy-mediated miR-29b expression participates in the initiation and progression of cervical cancer through suppressing the proliferation, EMT procedure and angiogenesis of cervical cancer cells by targeting STAT3 signal pathway.

miR-124 represses the mesenchymal features and suppresses metastasis in Ewing sarcoma.

Metastasis is the most powerful predictor of poor outcome of Ewing sarcoma (ES). Thus, identification of new molecules involved in tumor metastasis is of crucial importance to reduce morbidity and mortality of this devastating disease. In this study, we found that miR-124, a highly conserved miRNA, was suppressed in ES tissues and might be associated with tumor metastasis through suppressing its mesenchymal features. Overexpression of miR-124 suppressed the invasion of ES cells in vitro and tumor metastasis in vivo, which might be achieved through suppressing its mesenchymal features, as overexpression of miR-124 could repress the mesenchymal genes expression, and inhibit cell differentiation to mesenchymal lineages in ES cells. However, when SLUG was experimentally restored in these cells, mesenchymal features including suppressed expression of mesenchymal genes and decreased invasive ability were observed. We also found that cyclin D2 (CCND2) was a novel target gene of miR-124, and was directly involved in miR-124-mediated suppressive effects on cell growth. Lastly, we found that treatment with 5-Aza-CdR restored the expression of miR-124, accompanied with suppressed cell proliferation, invasion and mesenchymal features of ES cells, which demonstrated that hypermethylation might be involved in the regulation of miR-124 expression. Collectively, our data suggest that hypermethylation-mediated suppression of miR-124 might be involved in the tumor initiation and metastasis through suppressing the mesenchymal features of ES cells.

Overexpression of miR-140 Inhibits Proliferation of Osteosarcoma Cells via Suppression of Histone Deacetylase 4.

miRNAs play a pivotal role in the development and progression of osteosarcoma (OS). Previous studies indicated that miR-140 acts as a tumor suppressor in many cancers. However, its accurate expression and exact function in OS cells remain unknown. Herein, we demonstrated the lower expression of miR-140 in 40 paired OS tissues. Restoring miR-140 expression in OS cells had a marked effect on inhibiting cell proliferation and invasion, inducing cell apoptosis in vitro, and suppressing tumor growth in vivo. Moreover, a bioinformatics prediction indicated that the histone deacetylase 4 (HDAC4) is a target gene of miR-140 and is involved in miR-140-mediated suppressive effects. In conclusion, our findings show that miR-140 acts as a tumor suppressor in OS by targeting HDAC4.

Increased sorbitol levels in the hypertrophic ligamentum flavum of diabetic patients with lumbar spinal canal stenosis.

The pathomechanism of the ligamentum flavum (LF) hypertrophy in diabetic patients with lumbar spinal canal stenosis (LSCS) remains unclear. A cross-sectional study was undertaken to investigate the mechanism of LF hypertrophy in these patients. Twenty-four diabetic and 20 normoglycemic patients with LSCS were enrolled in the study. The structure of the LF in the study subjects was evaluated using histological and immunohistochemical methods, and the levels of sorbitol, pro-inflammatory cytokines, and the fibrogenic factor, TGF-ß1, in the LF were analyzed. In vitro experiments were performed using NIH3T3 fibroblasts to evaluate the effect of high-glucose conditions and an aldose reductase inhibitor on the cellular production of sorbitol, pro-inflammatory factors, and TGF-ß1. We found that the LF of diabetic patients exhibited significantly higher levels of sorbitol and pro-inflammatory cytokines, TGF-ß1 and of CD68-positive staining than that of the normoglycemic subjects. The diabetic LF was significantly thicker than that of the controls, and showed evidence of degeneration. The high glucose-cultured fibroblasts exhibited significantly higher levels of sorbitol, pro-inflammatory factors, and TGF-ß1 compared to the low glucose-cultured cells, and these levels were dose-dependently reduced by treatment with the aldose reductase inhibitor. Taken together, our data suggests that increased sorbitol levels in the LF of diabetic patients results in increased production of pro-inflammatory and fibrogenic factor, which contribute to LF hypertrophy, and could increase the susceptibility of diabetic patients to LSCS. Furthermore, aldose reductase inhibition effectively reduced the levels of sorbitol and sorbitol-induced pro-inflammatory factor expression in high glucose-cultured fibroblasts. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1058-1066, 2017.

A dual PI3K/AKT/mTOR signaling inhibitor miR-99a suppresses endometrial carcinoma.

Activation of the PI3K/AKT/mTOR signaling pathway, a common mechanism in all subtypes of endometrial cancers (EC), plays an important role in the initiation and progression of many cancers. Inhibitors against various components of this pathway might promise a novel effective approach for targeted therapy for EC in the future. Intriguingly, two major members of this pathway, AKT1 and mTOR, were both reported to be the putative target genes of miR-99a, which were widely reported to function as a tumor suppressor in a variety of cancers. However, the direct role of miR-99a in endometrial cancer progression and the signaling pathways might been involved have never been deciphered. In this paper, we demonstrate that the expression of miR-99a was significantly suppressed in the EC tissues and was negatively correlated with the differentiation of tumors. Furthermore, we find that overexpression of miR-99a in EC cells induced a complex phenotype, namely an inhibition of cell proliferation, block of G1/S phase transition, induction of cell apoptosis, suppression of cell invasion, and inhibition of tumor growth in vivo, which was mediated, at least partially, through dual-suppression of PI3K/AKT/mTOR pathway. This finding not only helps us understand the molecular mechanism of endometrial carcinogenesis, but also gives us a strong rationale to further investigate miR-99a as a potential biomarker and therapeutic target for EC.

Let-7a suppresses macrophage infiltrations and malignant phenotype of Ewing sarcoma via STAT3/NF-κB positive regulatory circuit.

The interaction between tumors cells, tumor-derived humoral factors and the bone marrow in the bone niches has been shown to be essential for bone tumor initiation and promotion. Among the tumor stromal cells, tumor-associated macrophages (TAMs) are usually the most abundant immune population. Previously, we reported that let-7a functions as a tumor suppressor in ES. Herein, we found that the suppressive effects are not only limited on the malignant phenotype of tumor cells but also on the regulation of macrophage infiltration. We observed that the let-7a expression is negatively related to macrophage infiltrations in ES. Moreover, overexpression of putative ts-miRNA let-7a significantly suppressed the recruitment of PBMCs in vitro and decreased the macrophage infiltrations in ES-xenografted tumors in vivo. Most importantly, a positive regulatory feedback loop consisting of let-7a, signal transducer and activator of transcription 3 (STAT3), and nuclear factor-kappa B (NF-κB) (let-7a/STAT3/NF-κB) was involved in let-7a-mediated suppressive effects. These data might provide evidence of a novel intracellular signaling network function in ES pathogenesis, and manipulating this novel feedback loop will have therapeutic potential for ES patients.

Let-7a functions as a tumor suppressor in Ewing's sarcoma cell lines partly by targeting cyclin-dependent kinase 6.

MicroRNAs play an important role in the development and progression of Ewing's sarcoma (ES). Especially, the expression of let-7a has been reported to be significantly downregulated in various cancers, and can affect the initiation and maintenance of tumor progression. However, the relative effects of let-7a on ES cells and relative mechanisms are largely unknown. In this study, we identified the underexpression of let-7a in human ES cells comparing with the human mesenchymal stem cells. Then, we sought to compensate for its loss through exogenous transfection with let-7a mimic into ES cell lines A673 and SK-ES-1. Restored let-7a expression inhibited cell proliferation, migration, as well as invasion; arrested cell cycle progression; and induced cell apoptosis of both cell lines. Moreover, bioinformatic prediction suggested that cyclin-dependent kinase 6 (CDK6), which is overexpressed and functions as an oncoprotein in ES cells, is a putative target gene of let-7a. Using mRNA and protein expression analysis and luciferase assays, we further identified the target role of CDK6. Finally, we found that restored CDK6 expression in ES cells that had been treated with let-7a mimic before could partly dampen let-7a-mediated tumor suppression. Taken together, our results showed that let-7a acted as a tumor suppressor in ES by targeting CDK6, and it may provide novel diagnostic and therapeutic options for human Ewing sarcoma clinical operation in future.

The up-regulation of miR-199b-5p in erythroid differentiation is associated with GATA-1 and NF-E2.

MicroRNAs (miRNAs) represent a class of small non-coding regulatory RNAs that play important roles in normal hematopoiesis, including erythropoiesis. Although studies have identified several miRNAs that regulate erythroid commitment and differentiation, we do not understand the mechanism by which the crucial erythroid transcription factors, GATA-1and NF-E2 directly regulate and control differentiation via miRNA pathways. In this study, we identified miR-199b-5p as a key regulator of human erythropoiesis, and its expression was up-regulated during the erythroid differentiation of K562 cells. Furthermore, the increase of miR-199b-5p in erythroid cells occurred in a GATA-1- and NF-E2-dependent manner during erythrocyte maturation. Both GATA-1 and NF-E2 bound upstream of the miR-199b gene locus and activated its transcription. Forced expression of miRNA-199b-5p in K562 cells affected erythroid cell proliferation and maturation. Moreover, we identified c-Kit as a direct target of miR-199b-5p in erythroid cells. Taken together, our results establish a functional link among the erythroid transcription factors GATA-1/NF-E2, miR-199b-5p and c-Kit, and provide new insights into the coupling of transcription and post-transcription regulation in erythroid differentiation.

A feedback loop consisting of microRNA 23a/27a and the ß-like globin suppressors KLF3 and SP1 regulates globin gene expression.

The developmental stage-specific expression of the human ß-like globin genes has been studied for decades, and many transcriptional factors as well as other important cis elements have been identified. However, little is known about the microRNAs that potentially regulate ß-like globin gene expression directly or indirectly during erythropoiesis. In this study, we show that microRNA 23a (miR-23a) and miR-27a promote ß-like globin gene expression in K562 cells and primary erythroid cells through targeting of the transcription factors KLF3 and SP1. Intriguingly, miR-23a and miR-27a further enhance the transcription of ß-like globin genes through repression of KLF3 and SP1 binding to the ß-like globin gene locus during erythroid differentiation. Moreover, KLF3 can bind to the promoter of the miR-23a∼27a∼24-2 cluster and suppress this microRNA cluster expression. Hence, a positive feedback loop comprised of KLF3 and miR-23a promotes the expression of ß-like globin genes and the miR-23a∼27a∼24-2 cluster during erythropoiesis.