miR-298 plays a pivotal role in colon cancer invasiveness by targeting PTEN.

Evidence indicate that the miR-298 dysregulation might associate with colorectal cancer (CRC) development. Herein, we evaluated the effect of miR-298 dysregulation on colon cancer invasiveness. First, metabolic activity, cell cycle progression, apoptosis, and invasion of miR-298 overexpressed/knocked out colon cancer cells were examined and combined with their transcriptome analysis data for better visualization of miR-298 intracellular signaling networks. Interaction between miR-298 and its target was evaluated with luciferase assay and validated using western blot analysis. The proportion of abnormal miR-298 level was investigated in tumor samples, matched normal adjacent tissues, and plasmas of 100 CRC patients, and also compared with 100 normal plasma samples. The Mann-Whitney U test was performed to assess miR-298 differences among the studied groups, and the correlation between miR-298 and the risk of CRC was shown by univariate and multivariate logistic regression. The data indicate that miR-298 overexpression promoted proliferation and metastasis in CRC cells via targeting phosphatase and tensin homolog. Comparative analysis of CRC tumors, normal adjacent tissues, and plasmas indicated a significant miR-298 upregulation in tumors and plasmas (1.72-fold and 1.65-fold, respectively; p < .001). Also, the aberrant level of miR-298 contributed with CRC tumor differentiation, TNM stage and lymph node metastasis (p < .001), and independently associated with poor survival of CRC patients (p < .029; hazard ratio: 1.292; 95% confidence interval: 0.339-2.184). Collectively, these data showed that abnormal level of miR-298 correlated with cancer development and through that lowered the overall survival rate of CRC patients. Therefore, miR-298 could be considered as a therapeutic target for CRC.

MiR-298 Exacerbates Ischemia/Reperfusion Injury Following Ischemic Stroke by Targeting Act1.

BACKGROUND/AIMS: This study investigated the role of the microRNA miR-298 and its target Act1 in ischemic stroke. METHODS: Cell viability was assessed with the 3-(4,5-dimethythiazol-2- yl)-2,5-diphenyl tetrazolium bromide assay. Apoptotic cells were detected by flow cytometry, and mRNA and protein expression were assessed by quantitative real-time PCR and western blotting, respectively. The regulatory relationship between miR-298 and Act1 was evaluated with the luciferase assay. To clarify the role of Act1 following ischemic stroke, the transcript was knocked down by short interfering RNA. The in vitro findings were validated in a mouse model of middle cerebral artery occlusion by administration of miR-298 mimic. RESULTS: Act1 was upregulated whereas miR-298 was downregulated in ischemic stroke. miR-298 overexpression by transfection of a mimic suppressed Act1 protein levels in vitro and in vivo, and the luciferase assay showed that miR-298 directly binds to the 3' untranslated region of the Act1 transcript. miR-298 overexpression enhanced cell apoptosis and autophagy and exacerbated ischemic infarction and neurological deficits, effects that were exerted via negative regulation of Act1/c-Jun N-terminal kinase (JNK)/nuclear factor (NF)-κB signaling and downstream autophagy pathways. CONCLUSIONS: Upregulation of miR-298 following ischemic stroke promotes brain injury in vitro and vivo by inhibiting the Act1/JNK/NF-κB signaling cascade and the downstream autophagy pathway. Therapeutic strategies that target miR-298 could be beneficial for the treatment of ischemic stroke.

MicroRNA-298 determines the radio-resistance of colorectal cancer cells by directly targeting human dual-specificity tyrosine(Y)-regulated kinase 1A.

BACKGROUND: Radiotherapy stands as a promising therapeutic modality for colorectal cancer (CRC); yet, the formidable challenge posed by radio-resistance significantly undermines its efficacy in achieving CRC remission. AIM: To elucidate the role played by microRNA-298 (miR-298) in CRC radio-resistance. METHODS: To establish a radio-resistant CRC cell line, HT-29 cells underwent exposure to 5 gray ionizing radiation that was followed by a 7-d recovery period. The quantification of miR-298 levels within CRC cells was conducted through quantitative RT-PCR, and protein expression determination was realized through Western blotting. Cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and proliferation by clonogenic assay. Radio-induced apoptosis was discerned through flow cytometry analysis. RESULTS: We observed a marked upregulation of miR-298 in radio-resistant CRC cells. MiR-298 emerged as a key determinant of cell survival following radiation exposure, as its overexpression led to a notable reduction in radiation-induced apoptosis. Intriguingly, miR-298 expression exhibited a strong correlation with CRC cell viability. Further investigation unveiled human dual-specificity tyrosine(Y)-regulated kinase 1A (DYRK1A) as miR-298's direct target. CONCLUSION: Taken together, our findings underline the role played by miR-298 in bolstering radio-resistance in CRC cells by means of DYRK1A downregulation, thereby positioning miR-298 as a promising candidate for mitigating radio-resistance in CRC.

Antidepressant-Like Effect of Geniposide in Mice Exposed to a Chronic Mild Stress Involves the microRNA-298-5p-Mediated Nox1.

Depression is a common mental disorder that presents a considerable challenge for public health. The natural product geniposide has neuroprotective effects on depression, but the underlying mechanism behind these effects had remained undefined. The present study was designed to investigate the role of microRNAs (miRs) in this mechanism. It studied mice with depression-like behavior established by exposure to chronic unpredictable mild stress (CUMS) for 2 months. The CUMS mice were intragastrically fed with geniposide at a dose of 10 ml/kg daily for two consecutive weeks. We monitored the depression-like behaviors of the CUMS mice by the forced swimming test (FST) and tail suspension test (TST). Then, we measured the cerebral expression of miR-298-5p and NADPH oxidase 1 (Nox1) mRNA in the CUMS mice by the RT-qPCR. The targeting relationship between miR-298-5p and Nox1 was evaluated by dual-luciferase reporter gene assay. The concentrations of adenosine triphosphate (ATP) and reactive oxygen species (ROS) were determined by the CellTiter-Glo® and flow cytometry, respectively. The mitochondrial membrane potential (MMP) was detected using JC-1 staining. Moreover, the expression of inflammatory cytokines (TNF-α, IL-1ß, IL-6, and TGF-ß) was determined by ELISA, RT-qPCR, and western blot analysis. We found that miR-298-5p was poorly-expressed while Nox1 was highly-expressed in the brain tissues of the CUMS-induced mice. Intriguingly, Geniposide treatment reversed the behavioral abnormalities of CUMS mice, including shortened immobility time. Geniposide inhibited the Nox1 expression by increasing miR-298-5p levels. There were increased ATP content and MMP and reduced contents of ROS and inflammatory cytokines in the CUMS mice receiving geniposide treatment. Hence, this study revealed an antidepressant effect of geniposide on CUMS-induced depression-like behavior in mice by down-regulating the miR-298-5p-targeted Nox1. This highlights a novel candidate target for the treatment of depression.

MicroRNA-298 Reverses Multidrug Resistance to Antiepileptic Drugs by Suppressing MDR1/P-gp Expression in vitro.

P-glycoprotein (P-gp), a critical multidrug transporter, recognizes and transports various antiepileptic drugs (AEDs) through the blood-brain barrier (BBB). This may decrease the concentrations of AEDs in brain tissues and cause multidrug resistance (MDR) in patients with refractory epilepsy. Compelling evidence indicates that microRNAs (miRNAs) modulate MDR in various cancers by regulating P-gp expression. Furthermore, a previous study showed that miR-298 mediates MDR in breast cancer cells by downregulating P-gp expression. Based on the therapeutic results obtained from tumor cells, we aimed to determine whether miR-298 reverses MDR to AEDs by regulating P-gp expression in the BBB. We first established different drug-resistant cell lines, including PHT-resistant HBMECs (human brain microvascular endothelial cells) and doxorubicin (DOX)-resistant U87-MG (human malignant glioma) cells, by inducing P-gp overexpression. Quantitative real-time PCR (qRT-PCR) analysis revealed reduced expression of miR-298 in both HBMEC/PHT and U87-MG/DOX cells, and the luciferase reporter assay identified the direct binding of miR-298 to the 3'-untranslated region (3'-UTR) of P-gp. Moreover, ectopic expression of miR-298 downregulated P-gp expression at the mRNA and protein levels, thereby increasing the intracellular accumulation of AEDs in drug-resistant HBMEC/PHT and U87-MG/DOX cells. Thus, our findings suggest that miR-298 reverses MDR to AEDs by inhibiting P-gp expression, suggesting a potential target for overcoming MDR in refractory epilepsy.

MicroRNA-298 represses hepatocellular carcinoma progression by inhibiting CTNND1-mediated Wnt/ß-catenin signaling.

MicroRNAs (miRNAs) are solid factors involved in the initiation and progression of hepatocellular carcinoma (HCC). Recently, miR-298 is recognized as a cancer-associated miRNA in breast, gastric and ovarian cancer. However, the functional role of miR-298 and its underlying mechanism are rarely reported in HCC. Herein, we found that the expression of miR-298 was down-regulated in HCC tissues and cell lines. The in vitro experiments showed that miR-298 overexpression inhibited cell proliferation, migration and invasion, and induced G1 arrest and apoptosis of HCC cells. miR-298 knockdown exerted an opposite effect on these cellular behaviors of HCC cells. Moreover, miR-298 restoration suppressed HCC tumor growth and metastasis in vivo. Additionally, catenin delta 1 (CTNND1) was demonstrated to be a direct target of miR-298 in HCC cells. CTNND1 knockdown led to similar effects with miR-298 overexpression on HCC cell proliferation, cell cycle progression, apoptosis and mobility. CTNND1 restoration reversed miR-298-induced inhibitory effects on HCC cells. Mechanistically, both miR-298 overexpression and CTNND1 knockdown repressed Wnt/ß-catenin signaling and resulted in reduced expression of ß-catenin, WNT11, Cyclin D1 and MMP7 in HCCLM3 cells. While, CTNND1 restoration abolished miR-298-induced inactivation of Wnt/ß-catenin signaling. In conclusion, our findings provide the first evidence that miR-298 suppresses HCC progression at least partially by targeting CTNND1-mediated Wnt/ß-catenin signaling. MiR-298 may be a target for new therapies in HCC patients.

MicroRNA-298 inhibits malignant phenotypes of epithelial ovarian cancer by regulating the expression of EZH2.

MicroRNA (miRNA or miR)-298 has been reported to be downregulated and to modify the expression of the polycomb protein enhancer of zeste 2 (EZH2) in recurrent epithelial ovarian cancer (EOC). To date, no functional evidence of a miR-298-EZH2 axis in EOC has been documented. The present study aimed to investigate the associations of miR-298 and/or EZH2 expression with clinicopathological features of EOC patients, and revealed their roles in cell motility based on EOC cell lines. Reverse transcription-quantitative polymerase chain reaction was performed to detect the expression levels of miR-298 and EZH2 messenger RNA in human EOC tissues and cell lines. Wound healing and transwell assays were performed to determine the function of the miR-298-EZH2 axis on cell migration and invasion, respectively. Compared with normal tissues, miR-298 expression was significantly downregulated, while EZH2 expression was significantly upregulated, in human EOC tissues (both P=0.001). In addition, miR-298 downregulation and EZH2 upregulation were significantly associated with high clinical stage (both P=0.01) and pathological grade (both P=0.02) of EOC patients. Furthermore, the ectopic expression of miR-298 could efficiently inhibit cell migration and invasion. Notably, the overexpression of EZH2 could restore the cell migration and invasion abilities suppressed by miR-298. Our data offer convincing evidence that the dysregulation of the miR-298-EZH2 axis may be important in tumor progression of EOC patients. The present study also confirmed a tumor-suppressive role of miR-298 in modulating EOC cell motility by regulating the expression of EZH2, implying its potential as a novel miRNA-based therapeutic target for the treatment of human EOC.