Construction of lentivirus-based inhibitor of hsa-microRNA-338-3p with specific secondary structure

BMSC-Derived Exosomes Carrying miR-26a-5p Ameliorate Spinal Cord Injury via Negatively Regulating EZH2 and Activating the BDNF-TrkB-CREB Signaling

BACKGROUND

Spinal cord injury (SCI) is a destructive neurological and pathological state that causes major motor, sensory and autonomic dysfunctions. Bone marrow mesenchymal stem cells (BMSCs)-derived exosomes show great therapeutic potential for SCI. Exosomes derived from miR-26a-modified MSCs promote axonal regeneration following SCI. Our study aims to uncover the mechanisms by which BMSC-derived exosomes carrying miR-26a-5p regulate SCI.

METHODS

BMSCs and BMSC-derived exosomes were isolated and characterized by Oil Red O and alizarin red staining, transmission electron microscopy, flow cytometry, nanoparticle tracking analysis and Western blotting. PC12 cells were treated with lipopolysaccharides (LPS), and SCI was established through laminectomy with contusion injury in rats. Annexin-V staining, CCK-8 and EdU incorporation were applied to determine cell apoptosis, viability, and proliferation. Hematoxylin and Eosin, Nissl and TUNEL staining was used to evaluate SCI injury and apoptosis in the spinal cord. Luciferase and chromatin immunoprecipitation assays were applied to evaluate gene interaction.

RESULTS

BMSC-derived exosomes facilitated LPS-treated PC12 cell proliferation and inhibited apoptosis by delivering miR-26a-5p. Moreover, BMSC-derived exosomal miR-26a-5p alleviated SCI. Furthermore, miR-26a-5p inhibited EZH2 expression by directly binding to EZH2, and EZH2 inhibited BDNF expression via promoting H3K27me3. Increased phosphorylated CREB enhanced KCC2 transcription and expression by binding to its promoter. Knockdown of miR-26a-5p abrogated BMSC-derived exosome-mediated protection in LPS-treated PC12 cells, but it was reversed by KCC2 overexpression.

CONCLUSION

BMSC-derived exosomes carrying miR-26a-5p repressed EZH2 expression to promote BDNF and TrkB expression and CREB phosphorylation and subsequently increase KCC2 expression, thus protecting PC12 cells and ameliorating SCI.

GPX4 Alleviates Diabetes Mellitus-Induced Erectile Dysfunction by Inhibiting Ferroptosis

Pharmacological therapy of diabetes mellitus-induced erectile dysfunction (DMED) is intractable owig to the poor response to phosphodiesterase type 5 inhibitors (PDE5i). The surge in the number of diabetic patients makes it extremely urgent to find a novel therapy for DMED. Ferroptosis is a recently discovered form of cell death evoked by lipid peroxidation and is related to several diabetic complications. GPX4, an important phospholipid hydroperoxidase, can alleviate ferroptosis and maintain redox balance via reducing lipid peroxides. However, whether GPX4 can be a prospective target of DMED needs to be determined. Fifty rats were randomly divided into control group, DMED group, DMED + negative control group (DMED + NC group), DMED + low-dose group (1 × 10⁶ infectious units), and DMED + high-dose group (2 × 10⁶ infectious units). Erectile function was assessed 4 weeks after intracavernous injection of GPX4 or negative control lentivirus. The penile shafts were collected for subsequent molecular biological and histological analysis. The results demonstrated that erectile function of the rats in DMED and DMED + NC groups was extremely impaired and was improved in a dose-dependent manner with GPX4 lentivirus (GPX4-LV) injection. Additionally, upregulation of the ACSL4-LPCAT3-LOX pathway, iron overload, oxidative stress, fibrosis, and decreased endothelial and smooth muscle cell numbers were observed in the corpus cavernosum of DMED group. Meanwhile, the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway was inhibited, and the Ras homolog gene family member A (RhoA)/Rho-associated protein kinase (ROCK) pathway was promoted in DMED rats. The above histologic alterations and related molecular changes were alleviated after GPX4-LV injection. The results revealed that GPX4 improved erectile function by modulating ferroptosis during DMED progression. This finding is of paramount significance in deciphering the molecular mechanism of hyperglycemia-induced ferroptosis, thereby providing a prospective target for preventing the development of DMED.

Internal Ribosome Entry Site Dramatically Reduces Transgene Expression in Hematopoietic Cells in a Position-Dependent Manner

Bicistronic transgene expression mediated by internal ribosome entry site (IRES) elements has been widely used. It co-expresses heterologous transgene products from a message RNA driven by a single promoter. Hematologic gene delivery is a promising treatment for both inherited and acquired diseases. A combined strategy was recently documented for potential genome editing in hematopoietic cells. A transduction efficiency exceeding ~90% can be achieved by capsid-optimized recombinant adeno-associated virus serotype 6 (rAAV6) vectors. In this study, to deliver an encephalomyocarditis virus (EMCV) IRES-containing rAAV6 genome into hematopoietic cells, we observed that EMCV IRES almost completely shut down the transgene expression during the process of mRNA–protein transition. In addition, position-dependent behavior was observed, in which only the EMCV IRES element located between a promoter and the transgenes had an inhibitory effect. Although further studies are warranted to evaluate the involvement of cellular translation machinery, our results propose the use of specific IRES elements or an alternative strategy, such as the 2A system, to achieve bicistronic transgene expression in hematopoietic cells.

MicroRNA-338-3p suppresses tumor growth of esophageal squamous cell carcinoma in vitro and in vivo

Accumulating evidence has shown that microRNAs (miRNAs) are aberrantly expressed in human esophageal squamous cell carcinoma (ESCC) and are crucial in tumorigenesis, among which miR‑338‑3p has been examined to be downregulated in patients with ESCC. However, the role of miR‑338‑3p in ESCC remains to be elucidated. In the present study, the role of miR‑338‑3p on the growth and survival of an ESCC cell line was determined with several in vitro approaches and in nude mouse models. It was determined that miR‑338‑3p expression was frequently downregulated in ESCC tissue compared with corresponding adjacent non‑tumor tissue, and that its expression was significantly correlated with tumor stage and metastasis. Overexpression of miR‑338‑3p in ESCC cells suppressed cell proliferation, colony formation, migration and invasion, and induced cell arrest at the G0/G1 stage and cell apoptosis in vitro. In addition, it was demonstrated that overexpression of miR‑338‑3p significantly suppresses tumor growth of xenograft tumors in mice (P<0.05). These findings revealed that miR‑338‑3p may act as a tumor suppressor in ESCC, and its dysregulation may be involved in the initiation and development of human ESCC. In addition, it was suggested that miR‑338‑3p may be a potential therapeutic agent for treatment of ESCC.

Anti-miRNA-221 sensitizes human colorectal carcinoma cells to radiation by upregulating PTEN

AIM: To investigate the regulative effect of miRNA (miR)-221 on colorectal carcinoma (CRC) cell radiosensitivity and the underlying mechanisms.

METHODS: A human CRC-derived cell line was cultured conventionally and exposed to different doses of X-rays (0, 2, 4, 6 and 8 Gy). The total RNA and protein of the cells were extracted 24 h after irradiation, and the alteration of miR-221 and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) gene mRNA expression was detected by real-time reverse transcriptase polymerase chain reaction (PCR). The protein alteration of PTEN in the cells was detected by Western blotting. Caco2 cells were pretreated with or without anti-PTEN-siRNA prior to the addition of pre-miR-221 or anti-miR-221 using Lipofectamine 2000. Colony formation assay and flow cytometry analysis were used to measure the surviving cell fraction and the sensitizing enhancement ratio after irradiation. Additionally, PTEN 3′-untranslated region fragment was PCR amplified and inserted into a luciferase reporter plasmid. The luciferase reporter plasmid construct was then transfected into CRC cells together with pre-miR-221 or anti-miR-221, and the luciferase activity in the transfected cells was detected.

RESULTS: The X-ray radiation dose had a significant effect on the expression of miR-221 and PTEN protein in human Caco2 cells in a dose-dependent manner. The miR-221 expression level improved gradually with the increase in irradiation dose, while the PTEN protein expression level reduced gradually. miR-221 expression was significantly reduced in the anti-miR-221 group compared with the pre-miR-221 and negative control groups (P < 0.01). Anti-miR-221 upregulated expression of PTEN protein and enhanced the radiosensitivity of Caco2 cells (P < 0.01). Moreover, the inhibitory effect was dramatically abolished by pretreatment with anti-PTEN-siRNA, suggesting that the enhancement of radiosensitivity was indeed mediated by PTEN. A significant increase of luciferase activity was detected in CRC cells that were cotransfected with the luciferase reporter plasmid construct and anti-miR-221 (P < 0.01).

CONCLUSION: Anti-miR-221 can enhance the radiosensitivity of CRC cells by upregulating PTEN.

MicroRNA-338-3p inhibits colorectal carcinoma cell invasion and migration by targeting smoothened

OBJECTIVE

To investigate the regulative effect of microRNA-338-3p on colorectal carcinoma cell invasion and migration.

METHODS

The microRNA-338-3p expression pattern of colorectal carcinoma tissues and cell lines was detected by real-time reverse transcriptase polymerase chain reaction. The protein level of smoothened was detected by western blot analysis. Furthermore, colorectal carcinoma cells were pretreated with or without anti-smoothened-small interfering ribonucleic acid prior to the addition of pre-microRNA-338-3p or anti-microRNA-338-3p. The status of colorectal carcinoma cell invasion and that of migration were detected by transwell assay and wound healing assay, respectively.

RESULTS

The expression of microRNA-338-3p was significantly down-regulated in colorectal carcinoma tissues in comparison with those in the adjacent non-tumorous tissues, and the value was negatively related to advanced tumor, node, metastasis stage and local invasion. The expression of microRNA-338-3p in colorectal carcinoma cells transfected with pre-microRNA-338-3p p was significantly increased. Furthermore, over-expression of microRNA-338-3p inhibited the expression of smoothened protein in colorectal carcinoma cells, which showed obviously suppressed invasion and migration ability. The expression of microRNA-338-3p in colorectal carcinoma cells transfected with anti-microRNA-338-3p was significantly decreased. Moreover, the down-regulated expression of microRNA-338-3p caused the up-regulated expression of smoothened protein in colorectal carcinoma cells, which showed significantly enhanced invasion and migration ability. However, anti-smoothened-small interfering ribonucleic acid largely, but not completely, reversed the effects induced by blockage of microRNA-338-3p, suggesting that the regulative effect of microRNA-338-3p on colorectal carcinoma cell invasion and migration was indeed mediated by smoothened. Additionally, smoothened was identified as a direct target of microRNA-338-3p by luciferase assay.

CONCLUSIONS

MicroRNA-338-3p could inhibit colorectal carcinoma cell invasion and migration by inhibiting smoothened expression.

miRNA-338-3p suppresses cell growth of human colorectal carcinoma by targeting smoothened

AIM: To investigate the regulative effect of miRNA-338-3p (miR-338-3p) on cell growth in colorectal carcinoma (CRC).

METHODS: The lentiviral vector pLV-THM-miR-338-3p and pLV-THM-miR-338-3p-inhibitor were constructed. The recombinant viral vector encoding the pre-miR-338-3p or miR-338-3p-inhibitor and the two packaging plasmids psPAX2 and pMD2.G were cotransfected into human embryonic kidney 293T cells to package lentivirus. The supernatant containing the lentivirus particles was harvested to determine the viral titer, and this supernatant was then used to transduce CRC-derived cell line, SW-620. Flow cytometry was utilized for sorting the green fluorescent protein (GFP)⁺ cells to establish the SW-620 cell line stably expressing pre-miR-338-3p or miR-338-3p-inhibitor. Moreover, the expression of miR-338-3p was determined by real-time reverse transcriptase polymerase chain reaction, and Western blotting was used to detect the expression of the smoothened (SMO, the possible target of miR-338-3p) protein in SW-620 cells. Furthermore, the status of CRC cell proliferation and apoptosis were detected by 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide assay and flow cytometry, respectively.

RESULTS: Restriction enzyme digestion and DNA sequencing demonstrated that the lentiviral vector pLV-THM-miR-338-3p and pLV-THM-miR-338-3p-inhibitor were constructed successfully. GFP was expressed after the SW-620 cells were transduced by the lentivirus. Expression of miR-338-3p in SW-620 cells transduced with the lentivirus pLV-THM-miR-338-3p was significantly increased (relative expression 3.91 ± 0.51 vs 2.36 ± 0.44, P < 0.01). Furthermore, overexpression of miR-338-3p inhibited the expression of SMO protein in SW-620 cells, which showed obviously suppressed proliferation ability [cellular proliferation inhibition rate (CPIR) 61.9% ± 5.2% vs 41.6% ± 4.8%, P < 0.01]. Expression of miR-338-3p in SW-620 cells transduced with the lentivirus pLV-THM-miR-338-3p-inhibitor was significantly decreased (relative expression 0.92 ± 0.29 vs 2.36 ± 0.44, P < 0.01). Moreover, the downregulated expression of miR-338-3p caused upregulated expression of the SMO protein in SW-620 cells, which showed significantly enhanced proliferation ability (CPIR 19.2% ± 3.8% vs 41.6% ± 4.8%, P < 0.01). However, anti-SMO-siRNA largely, but not completely, reversed the effects induced by blockage of miR-338-3p, suggesting that the regulative effect of miR-338-3p on CRC cell growth was indeed mediated by SMO.

CONCLUSION: miR-338-3p could suppress CRC growth by inhibiting SMO protein expression.