Basic research to expand treatment options for multiple myeloma is greatly needed due to the refractory nature of the disease. Histone deacetylase (HDAC) inhibitors, which are epigenetic regulators, are attractive but have limited applications. MicroRNAs (miRNAs), which are also epigenetic regulators, are important molecules that may lead to future therapeutic breakthroughs. In this study, we comprehensively searched for miRNAs that are altered by HDAC inhibitors in myeloma cells. We identified miR-7-5p (miR-7) as a miRNA downregulated by HDAC inhibitors. Transfection of myeloma cell lines with miR-7 suppressed cell proliferation, induced apoptosis, and enhanced the effects of the HDAC inhibitor panobinostat. Expression of miR-7 was downregulated by c-Myc inhibition, but upregulated by bortezomib. Comprehensive examination of miR-7 targets revealed four candidates: SLC6A9, LRRC59, EXOSC2, and PSME3. Among these, we focused on PSME3, an oncogene involved in proteasome capacity in myeloma cells. PSME3 knockdown increases myeloma cell death and panobinostat sensitivity. In conclusion, miR-7, which is downregulated by HDAC inhibitors, is a tumor suppressor that targets PSME3. This miR-7 downregulation may be involved in HDAC inhibitor resistance. In addition, combinations of anti-myeloma drugs that complement changes in miRNA expression should be considered.

The circular RNA (circRNA) Cdr1as is conserved across mammals and highly expressed in neurons, where it directly interacts with microRNA miR-7. However, the biological function of this interaction is unknown. Here, using primary cortical murine neurons, we demonstrate that stimulating neurons by sustained depolarization rapidly induces two-fold transcriptional upregulation of Cdr1as and strong post-transcriptional stabilization of miR-7. Cdr1as loss causes doubling of glutamate release from stimulated synapses and increased frequency and duration of local neuronal bursts. Moreover, the periodicity of neuronal networks increases, and synchronicity is impaired. Strikingly, these effects are reverted by sustained expression of miR-7, which also clears Cdr1as molecules from neuronal projections. Consistently, without Cdr1as, transcriptomic changes caused by miR-7 overexpression are stronger (including miR-7-targets downregulation) and enriched in secretion/synaptic plasticity pathways. Altogether, our results suggest that in cortical neurons Cdr1as buffers miR-7 activity to control glutamatergic excitatory transmission and neuronal connectivity important for long-lasting synaptic adaptations.

BACKGROUND: We recently reported that upregulation of Musashi 2 (MSI2) protein in the rare neuromuscular disease myotonic dystrophy type 1 contributes to the hyperactivation of the muscle catabolic processes autophagy and UPS through a reduction in miR-7 levels. Because oleic acid (OA) is a known allosteric regulator of MSI2 activity in the biogenesis of miR-7, here we sought to evaluate endogenous levels of this fatty acid and its therapeutic potential in rescuing cell differentiation phenotypes in vitro. In this work, four muscle cell lines derived from DM1 patients were treated with OA for 24 h, and autophagy and muscle differentiation parameters were analyzed.
RESULTS: We demonstrate a reduction of OA levels in different cell models of the disease. OA supplementation rescued disease-related phenotypes such as fusion index, myotube diameter, and repressed autophagy. This involved inhibiting MSI2 regulation of direct molecular target miR-7 since OA isoschizomer, elaidic acid (EA) could not cause the same rescues. Reduction of OA levels seems to stem from impaired biogenesis since levels of the enzyme stearoyl-CoA desaturase 1 (SCD1), responsible for converting stearic acid to oleic acid, are decreased in DM1 and correlate with OA amounts.
CONCLUSIONS: For the first time in DM1, we describe a fatty acid metabolism impairment that originated, at least in part, from a decrease in SCD1. Because OA allosterically inhibits MSI2 binding to molecular targets, reduced OA levels synergize with the overexpression of MSI2 and contribute to the MSI2 > miR-7 > autophagy axis that we proposed to explain the muscle atrophy phenotype.

Spinal cord injury (SCI) is a complex problem in modern medicine. Fibroblast activation and fibroscarring after SCI impede nerve recovery. Non-coding RNA plays an important role in the progression of many diseases, but the study of its role in the progression of spinal fibrosis is still emerging. Here, we investigated the function of circular RNAs, specifically antisense to the cerebellar degeneration-related protein 1 (CDR1as), in spinal fibrosis and characterized its molecular mechanism and pathophysiology. The presence of CDR1as in the spinal cord was verified by sequencing and RNA expression assays. The effects of inhibition of CDR1as on scar formation, inflammation and nerve regeneration after spinal cord injury were investigated in vivo and in vitro. Further, gene expression of miR-7a-5p and protein expression of transforming Growth Factor Beta Receptor II (TGF-βR2) were measured to evaluate their predicted interactions with CDR1as. The regulatory effects and activation pathways were subsequently verified by miR-7a-5p inhibitor and siCDR1as. These results indicate that CDR1as/miR-7a-5p/TGF-βR2 interactions may exert scars and nerves functions and suggest potential therapeutic targets for treating spinal fibrotic diseases.

OBJECTIVE: The pathophysiological mechanisms underlying brain injury resulting from intracerebral hemorrhage (ICH) remain incompletely elucidated, and efficacious therapeutic interventions to enhance the prognosis of ICH patients are currently lacking. Previous research indicates that MicroRNA-7 (miR-7) can suppress the expression of Nod-like receptor protein 3 (NLRP3), thereby modulating neuroinflammation in Parkinson\'s disease pathogenesis. However, the potential regulatory effects miR-7 on NLRP3 inflammasome after ICH are yet to be established. This study aims to ascertain whether miR-7 mitigates secondary brain injury following experimental ICH by inhibiting NLRP3 and to investigate the underlying mechanisms.
METHODS: An ICH model was established by stereotaxically injecting 100 μL of autologous blood into the right basal ganglia of Sprague-Dawley (SD) rats. Subsequently, these rats were allocated into three groups: sham, ICH + Vehicle, and ICH + miR-7, each comprising 18 animals. Twelve hours post-modeling, rats received intraventricular injections of 10 μL physiological saline, 10 μL phosphate, and 10 μL phosphate-buffered saline solution containing 0.5 nmol of miR-7 mimics, respectively. Neurological function was assessed on day three post-modeling, followed by euthanasia for brain tissue collection. Brain water content was determined using the dry-wet weight method. The expression of inflammatory cytokines in cerebral tissues surrounding the hematoma was analyzed through immunohistochemistry and Western blot assays. These cytokines were re-evaluated using Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Moreover, bioinformatics tools were employed to predict miR-7\'s binding to NLRP3. A wild-type luciferase reporter gene vector and a corresponding mutant vector were constructed, followed by transfection of miR-7 mimics into HEK293T cells to assess luciferase activity.
RESULTS: Our study demonstrates that the administration of miR-7 mimics markedly reduced neurological function scores and attenuated brain edema in rats following ICH. A significant upregulation of NLRP3 expression in microglia/macrophage adjacent to the hematoma was observed, substantially reduced after the treatment with miR-7 mimics. Furthermore, this intervention ameliorated neurodegenerative changes and effectively decreased the protein and mRNA levels of pro-inflammatory cytokines, namely TNF-α, IL-1β, IL-6, and Caspase1, in the cerebral tissues proximate to the hematomas. In addition, miR-7 mimics distinctly inhibited the luciferase activity associated with the wild-type reporter gene, an effect not mirrored in its mutant variant.
CONCLUSIONS: The miR-7 suppressed NLRP3 expression in microglia/macrophage to reduce the production of inflammatory cytokines, leading to conducting certain neuroprotection post-ICH in rats.

Increasing evidence suggests mammalian Argonaute (Ago) proteins partition into distinct complexes within cells, but there is still little biochemical or functional understanding of the miRNAs differentially associated with these complexes. In naïve T cells, Ago2 is found almost exclusively in low molecular weight (LMW) complexes which are associated with miRNAs but not their target mRNAs. Upon T-cell activation, a proportion of these Ago2 complexes move into a newly formed high molecular weight (HMW) RNA-induced silencing complex (RISC), which is characterized by the presence of the GW182 protein that mediates translational repression. Here, we demonstrate distinct partitioning of miRNAs and isomiRs in LMW versus HMW RISCs upon antigen-mediated activation of CD8+ T cells. We identify miR-7 as highly enriched in HMW RISC and demonstrate that miR-7 inhibition leads to increased production of IL-2 and up-regulation of the IL-2 receptor, the transferrin receptor, CD71 and the amino acid transporter, CD98. Our data support a model where recruitment of miR-7 to HMW RISC restrains IL-2 signaling and the metabolic processes regulated by IL-2.

Aim: Neo-adjuvant chemotherapy is a common approach for the complex treatment of breast cancer (BC) and paclitaxel (PTX) is frequently included in the therapeutic regimen. However, the effect of PTX-based treatment is hard to predict precisely based on routinely used markers. As microRNAs are considered a new promising class of biomarkers, the link between miRNA expression and PTX resistance of BC cells needs to be well investigated. This study aimed at the identification of miRNAs associated with responses of BC cells to PTX. Methods: Intrinsic PTX sensitivity and miRNA profiling were assayed in five BC cell lines to identify candidate miRNAs. Selected miRNA (n. 15) expressions were analyzed by real-time-quantitative polymerase chain reaction (RT-qPCR) in BC tissue samples (n. 31) obtained from a diagnostic biopsy. Results were analyzed in the context of the effect of two cycles of PTX and the effect of the completed scheme of neoadjuvant therapy. The study\'s design facilitated the evaluation of the effect of PTX on cells and the identification of features of the microRNA expression profiles associated exclusively with sensitivity to this drug. Results: miR-186 and miR-7 expression in BC tissues was higher in patients with better outcomes of PTX-based neoadjuvant therapy. Conclusion: High expressions of miR-186 and miR-7 are associated with good response to PTX, whereas their low expressions may be associated with resistance to PTX in BC, indicating the possibility of developing innovative test systems for the prediction of the PTX response, which can be used before the start of neo-adjuvant chemotherapy for BC.

Adoptive-cell-therapy (ACT) is important therapeutic approach against cancer. We previously showed that miR-7 deficiency endowed CD4+T cells with hyperactivation status in liver injury. However, whether CD4+T cells with miR-7 deficiency could elicit antitumor effect in ACT is still unclear. Naïve CD4+CD62Lhi T cells were purified from CD45.2 WT or CD45.2 miR-7def mice and transferred into syngeneic CD45.1WT mice bearing with lung tumor cells. The infiltration and function of T cells were measured by FCM and immunofluorescence assay. And naïve CD4+CD62Lhi T cells were purified from CD45.2 WT or CD45.2 miR-7def mice, then the cells were activated with CD3 antibody plus CD28 antibody in vitro for 24 h. Then, the cultured supernatant of LLC tumor cells or cytokines IFN-γ and IL-12 was added to establish Th1 polarization. Under these conditions, Th1 polarization-related molecules in these cells were analyzed by flow cytometry. Our data demonstrated a significant reduction in the growth and metastasis of lung cancer cells in the miR-7def CD4+T cell-transferred group, accompanied by a significant enhancement in the infiltration, proliferation, activation, and Th1 polarization of CD4+ T cells. Moreover, we observed the proliferation; activation of tumor-infiltrating CD8+ T cells was significantly increased in the local tumor of the CD45.2 miR-7def CD4+ T cell-transferred group, compared to the CD45.2 WT CD4+ T cell-transferred group. It is noteworthy that MAPK4, a target molecule of miR-7, was upregulated in CD4+ T cells from lung tumor tissues, resulting in an altered transduction of phosphorylation of NF-κB as well as AKT and ERK in vivo and in vitro. miR-7 deficiency promoted Th1-polarization of CD4+ T cells and elicited effective antitumor immune responses in ACT.

BACKGROUND: The epithelial immunomodulation and regeneration are intrinsic critical events against inflammatory bowel disease (IBD). MiR-7 is well documented as a promising regulator in the development of various diseases including inflammatory diseases.
OBJECTIVE: This study aimed to assess the effect of miR-7 in intestinal epithelial cells (IECs) in IBD.
METHODS: MiR-7def mice were given dextran sulfate sodium (DSS) to induce enteritis model. The infiltration of inflammatory cells was measured by FCM and immunofluorescence assay. 5\'deletion assay and EMSA assays were performed to study the regulatory mechanism of miR-7 expression in IECs. The inflammatory signals and the targets of miR-7 were analyzed by RNA-seq and FISH assay. IECs were isolated from miR-7def, miR-7oe and WT mice to identify the immunomodulation and regeneration capacity. IEC-specific miR-7 silencing expression vector was designed and administered by the tail vein into murine DSS-induced enteritis model to evaluate the pathological lesions of IBD.
RESULTS: We found miR-7 deficiency improved the pathological lesions of DSS-induced murine enteritis model, accompanied by elevated proliferation and enhanced transduction of NF-κB/AKT/ERK signals in colonic IECs, as well as decreased local infiltration of inflammatory cells. MiR-7 was dominantly upregulated in colonic IECs in colitis. Moreover, the transcription of pre-miR-7a-1, orchestrated by transcription factor C/EBPα, was a main resource of mature miR-7 in IECs. As for the mechanism, EGFR, a miR-7 target gene, was downregulated in colonic IECs in colitis model and Crohn\'s disease patients. Furthermore, miR-7 also controlled the proliferation and inflammatory-cytokine secretion of IECs in response to inflammatory-signals through EGFR/NF-κB/AKT/ERK pathway. Finally, IEC-specific miR-7 silencing promoted the proliferation and transduction of NF-κB pathway in IECs and alleviated the pathological damage of colitis.
CONCLUSIONS: Our results present the unknown role of miR-7/EGFR axis in IEC immunomodulation and regeneration in IBD and might provide clues for the application of miRNA-based therapeutic strategies in colonic diseases.

Dysregulation of cholesterol homeostasis is associated with several pathologies including cardiovascular diseases and neurological disorders such as Alzheimer\'s disease (AD). MicroRNAs (miRNAs) have emerged as key post-transcriptional regulators of cholesterol metabolism. We previously established the role of miR-7 in regulating insulin resistance and amyloidosis, which represents a common pathological feature between type 2 diabetes and AD. We show here an additional metabolic function of miR-7 in cholesterol biosynthesis. We found that miR-7 blocks the last steps of the cholesterol biosynthetic pathway in vitro by targeting relevant genes including DHCR24 and SC5D posttranscriptionally. Intracranial infusion of miR-7 on an adeno-associated viral vector reduced the expression of DHCR24 in the brain of wild-type mice, supporting in vivo miR-7 targeting. We also found that cholesterol regulates endogenous levels of miR-7 in vitro, correlating with transcriptional regulation through SREBP2 binding to its promoter region. In parallel to SREBP2 inhibition, the levels of miR-7 and hnRNPK (the host gene of miR-7) were concomitantly reduced in brain in a mouse model of Niemann Pick type C1 disease and in murine fatty liver, which are both characterized by intracellular cholesterol accumulation. Taken together, the results establish a novel regulatory feedback loop by which miR-7 modulates cholesterol homeostasis at the posttranscriptional level, an effect that could be exploited for therapeutic interventions against prevalent human diseases.