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Objective:Observing the effect of exosomes derived from hypoxic Bone marrow mesenchymal stem cells (BMSCs) on the function of chondrocytes, and exploring the role and mechanism of exosomal miR-196b-5p. Evaluating the application prospects of hypoxic BMSCs exosomes and miR-196b-5p for cartilage regeneration.Methods:Chondrocytes were cultured in the supernatant of BMSCs cultured under normoxia or hypoxia, respectively. The proliferation of chondrocytes was detected by CCK-8 assay and the expressions of Collagen type 2 (Col2), Col1, Aggrecan and SOX9 were detected by qPCR to evaluate the effect of hypoxic BMSCs paracrine on chondrocyte functions. Obtaining normoxic and hypoxic exosomes through ultracentrifugation, and testing their effects on the proliferation and anabolic-related genes of chondrocytes through CCK-8 assay and qPCR. Verifying the expression of miR-196b-5p in hypoxic exosomes based on exosomal miRNA array. Knocking out miR-196b-5p in hypoxic BMSCs, and detecting the effect of hypoxic exosomal miR-196b-5p on the functions of chondrocytes by loss-of-function assay. Predicting the downstream of miR-196b-5p through bioinformatics tools, and exploring the mechanism of hypoxic exosomal miR-196b-5p by gain-of-function assays. Hypoxic exosomes and miR-196b-5p-knockout hypoxic exosomes were loaded on silk fibroin hydrogel and subcutaneously into nude mice. After 4 weeks of culture, histological staining of saffron O, Masson and biochemical content of sGAG and collagen were performed to assess the application prospect of hypoxic exosomes and hypoxic exosomal miR-196b-5p on cartilage regeneration. Results:The results of CCK-8 assay and qPCR indicated that the supernatant of hypoxic BMSCs significantly promoted the proliferation of chondrocytes 1.20±0.07 and the expression of cartilage-related markers (Col2 2.95±0.17, Aggrecan 2.45±0.27, SOX9 2.92±0.29) compared to normoxic BMSCs (0.94±0.04, 1.89±0.09, 1.67±0.21, 1.76±0.16), the differences were statistically significant ( P<0.05). The result of CCK-8 assay showed that hypoxic exosomes (1.28±0.04) promoted the proliferation of chondrocytes compared to normoxic exosomes 1.05±0.06, the differences were statistically significant ( P<0.05). CCK-8 assay revealed that the down-regulation of miR-196b-5p in hypoxic exosomes 0.99±0.06 attenuated the proliferation of chondrocytes compared to control group 1.20±0.07, the differences were statistically significant ( P<0.05); the expression of Col2 0.56±0.04, Aggrecan 0.74±0.09, and SOX9 0.45±0.05 in chondrocytes was reduced in the miR-196b-5p knockdown group compared to the control group (1.00±0.09, 1.00±0.12, 1.00±0.07), the differences were statistically significant ( P<0.05). Co-transfection of pmirGLO-BACH1-WT reporter vector with miR-196b-5p mimics decreased the luciferase activity 0.73±0.06, the differences were statistically significant ( P<0.05). Co-transfection of pmirGLO-BACH1-MUT reporter vector with miR-196b-5p mimics showed no change in luciferase activity. BACH1 is the target of miR-196b-5p. Subcutaneous culture in nude mice showed that hypoxic exosomes significantly promoted the deposition of sGAG 383.2±21.54 and collagen 67.40±3.45, while reducing the expression of miR-196b-5p in hypoxic exosomes weakened the deposition of sGAG 258.4±19.50 and collagen 57.15±4.95, the differences were statistically significant ( P<0.05). Conclusion:Hypoxic exosomes promoted the functions of chondrocytes by inhibiting the expression of BACH1 through miR-196b-5p. Hypoxic exosomes can be applied in cartilage regeneration.
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Objective To construct miR-196b sponge lentiviral vector,and laid the foundation for studying the function of miR-196b in bone marrow stromal cells.Methods Based on the miR-196b mature sequence,a sequence consisting of 6 tandem repeats of the complementary sequence of miR-196b was designed,and which was cloned into pUC19 plasmid by using reverse PCR.Then the six-repeat sequence was cut and subcloned into pLVX-shRNA2 lentiviral vector.The lentivirus was packaged using 293T cells,and titer determination was done.The pLVX-shRNA2 lentivirus was used as the control group,and the 196b-sponge-pLVX lentivirus was the experimental group.Then ST2 cells were infected with the viruses,and the infection efficiency was calculated.The protein level of forkhead box O1 (FoxO1) was detected by Western blot assay.Results The identity of the sponge sequence was verified by sequencing.The titer of the sponge virus was 1 × 108 PFU/mL,and the infection efficiency reached 80％.Compared with the control group,the expression level of FoxO 1 protein was significantly increased (P ＜ 0.05).Conclusion The miR-196b sponge lentiviral vector is successfully constructed,and which has the capability to inhibit endogenous miR-196b.
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Objective To evaluate the expression of miR-196b in newly diagnosed pediatric acute myeloid leukemia (AML) and its clinical signiifcance. Methods Fifty-two AML children were enrolled in this study and 30 non-leukemia com-pared children were selected as controls. The expressions of miR-196b were detected in bone marrow samples by real-time quan-titative PCR (q-RT-PCR) and the results were expressed in 2-??Ct. Results miR-196b expressions were signiifcantly higher in M4-5 and lower in non-M4-5 of AML children than those in control (P<0.01), with a lowest level in t (15;17) and a highest level in MLL subtypes (P<0.01). The miR-196b expressions were signiifcantly different among different prognosis groups (P<0.01) and the level in the favorable prognostic group was lower than in poor prognosis group. It was also found that miR-196b expres-sion was lower in remission group than that in no-remission group after the ifrst induction remission therapy (P<0.05). Mean-while, the expression of miR-196b in the children with WBC≥100×109/L were statistically higher than that in the children with WBC<100×109/L (P<0.01), and miR-196b level was positively correlated with the platelet counts (r=0.302, P=0.030). Conclu-sions miR-196b expression is increased in poor prognosis group of AML children, and high expression of miR-196b is related with low response rate and poor prognosis. miR-1966 is expected to become a new target for the treatment of AML.
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Objective To study if 5-Aza-2’-deoxycytidine along or together with 4-phenylbutyric acid could affect miR-196b expression levels in chronic myeloid leukemia cells .Methods K562 cells were treated with DNA methylation inhibitor 5-Aza-2’-deoxycytidine, histone deacetylase inhibitors 4-phenylbutyric acid separately and the combined treatment with both of them, then expression levels of miR-196b were detected using Real-time PCR.Results The half inhibition concentration of 4-phenylbutyric acid was 1.58mmol/L.Comparing with the expression level of miR-196b in normal human bone marrow cells, the expression levels of miR-196b were significantly lower in Aza group , PBA group and negative control cells and nearly consistent among three groups , and as high as normal cells in combined treatment group . Conclusion The expression level of miR-196b in K562 cells could not return to normal treated with 5-Aza-2 ’-deoxycytidine or 4-phenylbutyric acid separately , while could restore normal when treated with both agents , indicating that miR-196b expression level in K562 cells is related with both DNA methylation and histone acetylation .
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Background and purpose: Colorectal cancer (CRC) is the most frequently occurring primary malignant tumor. Chemotherapy can reduce the risk of local and distant relapse. Therefore, it is very important to ifnd new biomarkers that can predict chemoresistant and help in treatment decisions. Methods:In this study, we examined the expression levels of 1 200 human miRNAs in 6 CRC tissues, using miRNA proifling assay arrays. A validation study was done to corroborate a subset of the results, including expression levels of miR-4299, miR-196b, miR-324-5p, miR-455-3p and miR-939, by analyzing 100 specimens of stageⅣcolorectal adenocarcinoma (not respond and respond to the chemotherapy) to quantitative real-time PCR. We modeled the relationship between the expression levels of these miRNAs and the survival rate of 100 CRC patients by Kaplan-Meier method. Results:Expression proifles in CRCs suggested that 5 miRNAs were candidate markers associated with the chemoresistance of colorectal cancer. We found that miR-4299 and-196b had signiifcant diagnostic value for chemoresistance CRC. miR-4299 yielded an AUC (the areas under the ROC curve) of 0.784 and miR-196b yielded an AUC of 0.647 in discriminating CRC from controls. Combined ROC analysis using these 2 miRNAs revealed an elevated AUC of 0.848 with 67.9%sensitivity and 90.9%speciifcity in discriminating chemoresistance CRC. The low level of miR-4299 expression and the high level of-196b expression are signiifcantly correlated with the good survival of CRC patients. Conclusion:These data suggest that miR-4299 and-196b have strong potential as novel biomarkers for chemoresistant detection of colorectal cancer.