Extracellular vesicles released by hypoxia-induced tumor-associated fibroblasts impart chemoresistance to breast cancer cells via long noncoding RNA H19 delivery

Recently, extracellular vesicles (EVs) have been emphasized in regulating the hypoxic tumor microenvironment of breast cancer (BC), where tumor-associated fibroblasts (TAFs) play a significant role. In this study, we describe possible molecular mechanisms behind the pro-tumoral effects of EVs, secreted by hypoxia (HP)-induced TAFs, on BC cell growth, metastasis, and chemoresistance. These mechanisms are based on long noncoding RNA H19 (H19) identified by microarray analysis. We employed an in silico approach to identify differentially expressed lncRNAs that were associated with BC. Subsequently, we explored possible downstream regulatory mechanisms. We isolated EVs from TAFs that were exposed to HP, and these EVs were denoted as HP-TAF-EVs henceforth. MTT, transwell, flow cytometry, and TUNEL assays were performed to assess the malignant phenotypes of BC cells. A paclitaxel (TAX)-resistant BC cell line was constructed, and xenograft tumor and lung metastasis models were established in nude mice for in vivo verification. Our observation revealed that lncRNA H19 was significantly overexpressed, whereas miR-497 was notably downregulated in BC. HP induced activation of TAFs and stimulated the secretion of EVs. Coculture of HP-TAF-EVs and BC cells led to an increase in TAX resistance of the latter. HP-TAF-EVs upregulated methylation of miR-497 by delivering lncRNA H19, which recruited DNMT1, thus lowering the expression of miR-497. In addition, lncRNA H19-containing HP-TAF-EVs hindered miR-497 expression, enhancing tumorigenesis and TAX resistance of BC cells in vivo. Our study presents evidence for the contribution of lncRNA H19-containing HP-TAF-EVs in the reduction of miR-497 expression through the recruitment of DNMT1, which in turn promotes the growth, metastasis, and chemoresistance of BC cells.

microRNA-497 prevents pancreatic cancer stem cell gemcitabine resistance, migration, and invasion by directly targeting nuclear factor kappa B 1

Objectives: Cancer stem cells (CSCs) comprise a small population of cells in cancerous tumors and play a critical role in tumor resistance to chemotherapy. miRNAs have been reported to enhance the sensitivity of pancreatic cancer to chemotherapy. However, the underlying molecular mechanism requires better understanding.

Methods: Cell viability and proliferation were examined with CCK8 assays. Quantitative real-time polymerase chain reaction was executed to assess mRNA expression. StarBase database was used to select the target genes of miRNA, which were further affirmed by dual luciferase assay. Transwell assay was used to analyze cell invasion and migration.

Results: We proved that miR-497 could be obviously downregulated in pancreatic cancer tissues and CSCs from Aspc-1 and Bxpc-3 cells. In addition, inhibition of miR-497 evidently accelerated pancreatic CSC gemcitabine resistance, migration and invasion. Moreover, we revealed that nuclear factor kappa B 1 (NFκB1) was prominently upregulated in pancreatic cancer tissues and pancreatic CSCs, and NFκB1 was also identified as a direct target of miR-497. Furthermore, we demonstrated that overexpression of NFκB1 could also notably promote the viability, migration, and invasion of gemcitabine-treated pancreatic CSCs, but this effect could be partially abolished by miR-497 overexpression.

Conclusions: Those findings suggest that miR-497 overexpression could suppress gemcitabine resistance and the metastasis of pancreatic CSCs and non-CSCs by directly targeting NFκB1.

Longitude Variation of the microRNA-497/FGF-23 Axis during Treatment and Its Linkage with Neoadjuvant/Adjuvant Trastuzumab-Induced Cardiotoxicity in HER2-Positive Breast Cancer Patients

Purpose

MicroRNA-497 (miR-497) is previously reported to target fibroblast growth factor 23 (FGF-23) and regulates cardiac injury, while their value in predicting drug-induced cardiotoxicity is not reported. Thus, the current study aimed to investigate the correlation of miR-497/FGF-23 with neoadjuvant/adjuvant trastuzumab-induced cardiotoxicity in human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients.

Methods

A total of 97 HER2-positive surgical breast cancer patients who received neoadjuvant/adjuvant trastuzumab contained regimens were enrolled; then, their peripheral blood mononuclear cells (PBMC) and serum were collected at baseline, after neoadjuvant treatment, at 3 months (M3), 6 months (M6), 9 months (M9), and 12 months (M12) after surgery. The PBMC was used for miR-497 measurements, and the serum was used for FGF-23 measurements. The cardiotoxicity events and incidence were recorded.

Results

A total of 24 (24.7%) patients occurred cardiotoxicity during the treatment period. MiR-497 decreased from baseline (median: 0.955) to M12 after surgery (median: 0.602) (p < 0.001), while FGF-23 increased from baseline (median: 0.390 ng/mL) to M12 after surgery (median: 0.566 ng/mL) (p < 0.001); besides, the miR-497/FGF-23 axis greatly reduced from baseline (median: 2.545) to M12 after surgery (median: 1.222) (p < 0.001). At most time points, miR-497 was negatively related to FGF-23 (all p < 0.05). Notably, the miR-497/FGF-23 axis at all time points (including baseline, postneoadjuvant treatment, M3, M6, M9, and M12) was related to a lower risk of cardiotoxicity (all p < 0.05). Furthermore, the miR-497/FGF-23 axis was also positively correlated with the left ventricular ejection fraction (LVEF) at all time points (all p < 0.01).

Conclusion

The MiR-497/FGF-23 axis serves as a potential indicator predicting trastuzumab-induced cardiotoxicity in HER2-positive breast cancer patients.

Expression and Diagnostic Value of miR-497 and miR-1246 in Hepatocellular Carcinoma

Objective

Serum microRNAs (miRNAs) may serve as biomarkers in various cancers. Our study aims to explore the roles of miR-497 and miR-1246 in hepatocellular carcinoma (HCC).

Methods

The expression levels of miR-497 and miR-1246 were measured by RT-PCR. A correlation analysis was conducted between the expression levels of miR-497 and miR-1246 and clinicopathological characteristics of patients. The receiver operating characteristic (ROC) curve was applied to evaluate the diagnostic efficacy in HCC. In addition, bioinformatics tools were also utilized to predict the potential targets of miR-497 and miR-1246.

Results

The expression level of miR-497 in HCC was significantly down-regulated compared with the control group while the miR-1246 revealed a significantly higher expression level in HCC. There was a significant correlation demonstrated between the expression levels of miR-497 and miR-1246 in preoperative serum of HCC and the differentiation degree, Tumor Node Metastasis (TNM) classification, and metastasis. The expression levels of serum miR-497 and miR-1246 were significantly associated with the diagnosis, prognosis, and overall survival rate of patients with HCC. Moreover, the potential target genes of miR-497 in HCC include ARL2, UBE2Q1, PHF19, APLN, CHEK1, CASK, SUCO, CCNE1, and KIF23. The low expression of these nine genes is associated with a better prognosis of HCC patients. AUTS2 is a novel target gene of miR-1246, and its low expression is significantly related to the low overall survival rate of HCC patients.

Conclusions

miR-497 and miR-1246 are possibly involved in the progression of HCC by regulating target genes, respectively, and could serve as biomarkers in HCC.

miR-497 inhibits proliferation and invasion in triple-negative breast cancer cells via YAP1

MicroRNA (miR)-497 has been reported as a tumor suppressor in various cancer types. Nonetheless, the regulation of triple-negative breast cancer (TNBC) by miR-497 remains poorly understood. The present study aimed to investigate the potential function and mechanism of miR-497 in TNBC. A total of 36 TNBC and matched non-cancerous tissue samples were collected for analysis. Reverse transcription-quantitative PCR was performed to detect the miR-497 levels in TNBC tissue. The association between miR-497 expression, clinical characteristics and survival was then analyzed. To investigate the role of miR-497 in TNBC, MTT, colony formation, Transwell invasion, cell cycle and cell apoptosis assays were conducted following transfection of miR-497 mimics into the MDA-MB-231 and MDA-MB-468 cell lines. Luciferase reporter assays and western blot analysis were used to confirm the regulation of a putative target of miR-497. The results indicated that the expression of miR-497 was downregulated in the TNBC specimens. Further analysis demonstrated that the expression of miR-497 was downregulated in patients with advanced TNBC stages and that low miR-497 was associated with poor prognosis in patients with TNBC. Transfection of miR-497 mimics inhibited TNBC cell proliferation and increased cell apoptosis in MDA-MB-231 and MDA-MB-468 cells. Moreover, cell migration was inhibited following overexpression of miR-497, which also led to the arrest of the breast cancer cells in the G₀/G₁ phase of the cell cycle. Yes-associated protein 1 (YAP1), a critical molecule in the Hippo pathway, was identified as a target of miR-497. Notably, the protein and mRNA expression levels of YAP1 in MDA-MB-231 and MDA-MB-468 cells were downregulated following overexpression of miR-497. Overall, the findings of the present study indicated that miR-497 inhibited TNBC cell proliferation and migration and induced cell apoptosis by negatively regulating YAP1 expression. Thus, targeting miR-497 may represent a potential strategy for the treatment of TNBC.

Methylation-mediated down-regulation of microRNA-497-195 cluster confers osteogenic differentiation in ossification of the posterior longitudinal ligament of the spine via ADORA2A

Aberrant expression of microRNAs (miRNAs) has been associated with spinal ossification of the posterior longitudinal ligament (OPLL). Our initial bioinformatic analysis identified differentially expressed ADORA2A in OPLL and its regulatory miRNAs miR-497 and miR-195. Hence, this study was conducted to clarify the functional relevance of miR-497-195 cluster in OPLL, which may implicate in Adenosine A2A (ADORA2A). PLL tissues were collected from OPLL and non-OPLL patients, followed by quantification of miR-497, miR-195 and ADORA2A expression. The expression of miR-497, miR-195 and/or ADORA2A was altered in posterior longitudinal ligament (PLL) cells, which then were stimulated with cyclic mechanical stress (CMS). We validated that ADORA2A was expressed highly, while miR-497 and miR-195 were down-regulated in PLL tissues of OPLL patients. miR-195 and miR-497 expression in CMS-treated PLL cells was restored by a demethylation reagent 5-aza-2'-deoxycytidine (AZA). Moreover, expression of miR-195 and miR-497 was decreased by promoting promoter CpG island methylation. ADORA2A was verified as the target of miR-195 and miR-497. Overexpression of miR-195 and miR-497 diminished expression of osteogenic factors in PLL cells by inactivating the cAMP/PKA signaling pathway via down-regulation of ADORA2A. Collectively, miR-497-195 cluster augments osteogenic differentiation of PLL cells by inhibiting ADORA2A-dependent cAMP/PKA signaling pathway.

Regulation of microRNA-497 expression in human cancer

MicroRNAs (miRNAs/miRs) are a type of non-coding single-stranded RNA, with a length of ~22 nt, which are encoded by endogenous genes and are involved in the post-transcriptional regulation of gene expression in animals and plants. Studies have demonstrated that miRNAs play an important role in the occurrence, development, metastasis, diagnosis and treatment of cancer. In recent years, miR-497 has been identified as one of the key miRNAs in a variety of cancer types and has been shown to be downregulated in a variety of solid tumors. However, the regulation of miR-497 expression involves a complex network, which is affected by several factors. The aim of the present review was to summarize the mechanism of regulation of miR-497 expression at the pre-transcriptional and transcriptional levels in cancer, as well as the role of miR-497 expression imbalance in cancer diagnosis, treatment and prognosis. The regulatory mechanisms of miR-497 expression may aid in our understanding of the causes of miR-497 expression imbalance and provide a reference value for further research on the diagnosis and treatment of cancer.

MicroRNA-497 elevation or LRG1 knockdown promotes osteoblast proliferation and collagen synthesis in osteoporosis via TGF-β1/Smads signalling pathway

MicroRNAs (miRNAs) have been corroborated to engage in the process of cellular activities in osteoporosis. However, few researches have been conducted to expose the integrated role of miR‐497, leucine‐rich alpha‐2‐glycoprotein‐1 (LRG1) and transforming growth factor beta 1 (TGF‐β1)/Smads signalling pathway in osteoporosis. Thereafter, the study is set out to delve into miR‐497/LRG1/TGF‐β1/Smads signalling pathway axis in osteoporosis. Osteoporosis bone tissues and normal bone tissues were collected. Rat osteoporosis models were constructed via ovariectomy. Model rats were injected with restored miR‐497 or depleted LRG1 to explore their roles in osteoporosis. Rat osteoblasts were extracted from osteoporosis rats and transfected with restored miR‐497 or depleted LRG1 for further verification. MiR‐497 and LRG1 expression in femoral head tissues and osteoblasts of osteoporosis rats were detected. TGF‐β1/Smads signalling pathway‐related factors were detected. MiR‐497 was poorly expressed while LRG1 was highly expressed and TGF‐β1/Smads signalling pathway activation was inhibited in osteoporosis. MiR‐497 up‐regulation or LRG1 down‐regulation activated TGF‐β1/Smads signalling pathway, promoted collagen type 1 synthesis and suppressed oxidative stress in femoral head tissues in osteoporosis. MiR‐497 restoration or LRG1 knockdown activated TGF‐β1/Smads signalling pathway, promoted viability and suppressed apoptosis of osteoblasts in osteoporosis. Our study suggests that miR‐497 up‐regulation or LRG1 down‐regulation promotes osteoblast viability and collagen synthesis via activating TGF‐β1/Smads signalling pathway, which may provide a novel reference for osteoporosis treatment.

MicroRNA-497/fibroblast growth factor-23 axis, a predictive indictor for decreased major adverse cardiac and cerebral event risk in end-stage renal disease patients who underwent continuous ambulatory peritoneal dialysis

OBJECTIVE

This study aimed at exploring the correlation of microRNA (miR)-497/fibroblast growth factor-23 (FGF-23) axis with major adverse cardiac and cerebral event (MACCE) occurrence in end-stage renal disease (ESRD) patients who underwent continuous ambulatory peritoneal dialysis (CAPD).

METHODS

Totally, 360 ESRD patients who underwent CAPD were enrolled. Their plasma samples were collected to detect miR-497 expression by real-time quantitative polymerase chain reaction, and FGF-23 level by enzyme-linked immunosorbent assay. All patients were followed up for 36 months, and the occurrence of MACCE during the follow-up was documented.

RESULTS

MiR-497 expression negatively correlated with FGF-23 level in ESRD patients who underwent CAPD (P < .001). The MACCE occurrence rate at 1, 2, and 3-year was 5.6%, 11.9%, and 15.0%, respectively. Furthermore, miR-497/FGF-23 axis high level (P < .001) and miR-497 high expression (P = .034) correlated with reduced accumulating MACCE occurrence, whereas FGF-23 high level (P = .008) correlated with increased accumulating MACCE occurrence. Forward stepwise multivariate Cox's regression disclosed that miR-497/FGF-23 axis high level (P = .008) was an independent predictive factor for lower accumulating MACCE occurrence, whereas age (≥55 years) (P < .001), body mass index (≥21.7 kg/m² ) (P = .006), peritoneal dialysis duration (≥61.0 months) (P < .001), C-reactive protein (≥4.7 mg/L) (P = .001), serum uric acid (≥409.4 μmol/L) (P = .009), β-fibrinogen (≥5.8 mmol/L) (P < .001), and low-density lipoprotein cholesterol (≥2.7 mmol/L) (P = .003) were independent factors for predicting higher accumulating MACCE occurrence.

CONCLUSION

MiR-497/FGF-23 axis holds clinical significance for predicting attenuated MACCE risk in ESRD patients who underwent CAPD.

Long Non-Coding RNA TTN-AS1 Promotes the Proliferation and Invasion of Colorectal Cancer Cells by Activating miR-497-Mediated PI3K/Akt/mTOR Signaling

Introduction

Long non-coding RNAs (lncRNAs) have obtained increasing attention due to their regulatory functions in many cancers. This work aimed to investigate the functional roles of lncRNA TTN-AS1 in colorectal cancer (CRC) and to explore the underlying mechanisms.

Methods

The expression profiles of TTN-AS1 and miR-497 in CRC tissues and cell lines were determined by RT-qPCR analysis. MTT assay, transwell assay, western blot analysis, and xenograft tumors in nude mice were employed to analyze the effects of TTN-AS1 on the proliferation, migration, invasion, EMT, and in vivo tumorigenesis of CRC cells. Bioinformatics analysis and dual-luciferase reporter assay determined the direct binding relation between TTN-AS1 and miR-497 in CRC.

Results

We observed a significant increase of TTN-AS1 expression level in CRC tissues and cell lines compared with normal counterparts. High expression of TTN-AS1 predicted a poor prognosis and was correlated with aggressive clinicopathological characteristics in CRC patients. Functionally, gain- and loss-of-function studies indicated that TTN-AS1 knockdown suppressed the proliferation, migration, invasion and epithelial–mesenchymal transition of CRC cells in vitro, whereas TTN-AS1 overexpression showed the complete opposite effects. Mechanistically, we found that TTN-AS1 could directly interact with miR-497, and co-transfection with miR-497 mimics blocked the activation of PI3K/Akt/mTOR signaling, and reversed the effects of TTN-AS1 overexpression in CRC cells.

Conclusion

To conclude, our findings provide novel insight into CRC tumorigenesis and indicate that TTN-AS1 may serve as a potential therapeutic target for CRC treatment.

Circular RNA PVT1 acts as a competing endogenous RNA for miR-497 in promoting non-small cell lung cancer progression

Circular RNAs (circRNAs) are a class of covalently closed non-coding RNAs and play crucial regulatory roles in human cancer biology. The purpose of the present study was to explore the expression pattern and biological role of circular RNA PVT1 (circPVT1) in non-small cell lung cancer (NSCLC). We firstly found that circPVT1 was overexpressed in clinical NSCLC tissues and cell lines. NSCLC patients with high expression of circPVT1 exhibited aggressive clinicopathological characteristics and poor prognosis. In vitro assays of the NSCLC cell lines (H1299 and A549 cells) demonstrated that knockdown of circPVT1 inhibited NSCLC cell proliferation and induced NSCLC cell apoptosis. We further found that circPVT1 served as a competing endogenous RNA of miR-497 and indirectly regulated Bcl-2 expression in NSCLC cells. Finally, inhibition of miR-497 abrogated the effects of circPVT1 knockdown in NSCLC cells. Taken together, the results from our study indicated circPVT1 acts as an oncogene in NSCLC, and may serve as a promising therapeutic target for NSCLC patients.

Long non-coding RNA LINC00978 promotes cell proliferation and tumorigenesis via regulating microRNA-497/NTRK3 axis in gastric cancer

Gastric cancer (GC) is the most common gastrointestinal malignancy in the digestive system. Recent studies have proven that long non-coding RNAs (lncRNAs) are closely related to tumor growth and metastasis. The study aimed to explore the effect of LINC00978 on GC cells proliferation and tumorigenesis. LINC00978 was up-regulated in GC tissues and cell lines. Up-regulation of LINC00978 was positively correlated with low survival rate. LINC00978 silence inhibited proliferation, metastasis, and promoted apoptosis in BGC-823 cells. Additionally, LINC00978 functioned as competing endogenous RNA to inhibit miR-497 expression. Further, NTRK3 was confirmed as a target gene of miR-497. Up-regulation of NTRK3 was found in GC tissues, and the positive correlation was presented between LINC00978 and NTRK3. Further, LINC00978 promoted cell proliferation and tumor weight by regulation of NTRK3. These findings demonstrated that LINC00978 promoted cell proliferation and tumorigenesis by regulating miR-497/NTRK3 axis in GC.

Prognostic Role of MicroRNA-497 In Cancer Patients: A Meta-analysis

Background: MicroRNA-497(miR-497) has been studied for its irreplaceable role of predicting the prognosis of various cancers, but there has been no systematic study to summarize the data. Consequently, we performed this meta-analysis to reveal the association between the expression level of miR-497 and cancer prognosis systematically.

Materials and Methods: PubMed was searched for appropriate studies and a total of 12 eligible publications with 989 cancer patients were recruited into our analysis to assess the strength of the association. Hazard ratios (HRs) and odds ratios (ORs) were analyzed to finish this work.

Results: The cancer patients who have high expressing level of miR-497 are less possible to have lymph node metastasis (OR = 0.25, 95% CI: 0.16-0.40, P < 0.001) and more likely to have favourable tumor-node-metastasis stage (OR = 0.29, 95% CI: 0.17-0.49, P < 0.001). Also, high miR-497 expression level was notably connected to better overall survival (pooled HR = 0.41, 95% CI: 0.32-0.53, P < 0.001).

Conclusions: High expressing levels of miR-497 might be a potential biomarker which can be used to predict the better prognosis of different cancer types.

MicroRNA-497 inhibits tumor growth through targeting insulin receptor substrate 1 in colorectal cancer

MicroRNAs (miRNAs) have been demonstrated to serve an important role in diverse biological processes and cancer progression. Downregulation of microRNA-497 (miR-497) has been observed in human colorectal cancer (CRC) tissues, but the function of miR-497 in CRC has not been well investigated. In the present study, it was demonstrated that expression of miR-497 was significantly downregulated in human CRC tissues compared to adjacent normal tissues. Enforced expression of miR-497 inhibited proliferation, migration and invasion abilities of CRC cell lines SW1116 and SW480. Furthermore, overexpression of miR-497 inhibited phosphoinositide 3-kinase/AKT and mitogen-activated protein kinase/extracellular signal-regulated kinase signaling by targeting insulin receptor substrate 1 (IRS1). In human clinical specimens, IRS1 was inversely correlated with miR-497 in CRC tissues. Collectively, the results of the present study demonstrate that miR-497 is a tumor suppressor miRNA and indicate its potential application for the treatment of human CRC in the future.

microRNA-497 overexpression decreases proliferation, migration and invasion of human retinoblastoma cells via targeting vascular endothelial growth factor A

The expression level and roles of microRNA-497 (miR-497) have been frequently reported in previous studies on cancer. However, its expression, function and associated molecular mechanisms in retinoblastoma remain unknown. In the present study, miR-497 expression levels in human retinoblastoma tissues, normal retinal tissues and retinoblastoma cell lines were determined using reverse transcription-quantitative polymerase chain reaction. In addition, a Cell Counting Kit-8 assay, cell migration assay, cell invasion assay, western blot analysis and Dual-Luciferase reporter assay were used to explore the expression, functions and molecular mechanisms of miR-497 in human retinoblastoma. It was demonstrated that miR-497 was significantly downregulated in retinoblastoma tissues and cell lines compared with normal retinal tissues. Ectopic expression of miR-497 decreased the proliferation, migration and invasion of retinoblastoma cells. Furthermore, VEGFA was verified as a potential direct target of miR-497 in vitro. Taken together, the results indicate that miR-497 functions as a tumor suppressor in the carcinogenesis and progression of retinoblastoma via targeting VEGFA. miR-497 should be investigated as a potential therapeutic target for the treatment of retinoblastoma.

Downregulation of microRNA-497 is associated with upregulation of synuclein γ in patients with osteosarcoma

The present study aimed to investigate the effects of microRNA (miRNA/miR)-497 expression levels on the expression levels of synuclein γ (SNCG) in serum samples, as well as osteosarcoma and lung-metastatic tissue samples, from patients with osteosarcoma. Between December 2010 and August 2013, fasting peripheral blood was collected from 36 patients with osteosarcoma for serum separation. In addition, osteosarcoma and lung metastatic tissues were resected from 15 osteosarcoma patients with lung metastasis by surgery. Bioinformatics was employed to predict the amount miRNA that binds to SNCG. Reverse transcription-quantitative polymerase chain reaction was used to determine the expression levels of SNCG and miR-497, and western blotting was performed to determine protein expression levels. It was observed that SNCG mRNA and protein expression levels were significantly upregulated in osteosarcoma tissues (P<0.01). Additionally, SNCG mRNA (P<0.01) and protein (P<0.05) expression levels were significantly upregulated in the blood of patients with osteosarcoma. SNCG mRNA and protein expression levels were also significantly upregulated in lung metastatic tissues (P<0.01). miR-497 was significantly downregulated in all three samples; therefore downregulation of miR-497 may lead to the occurrence, development and metastasis of osteosarcoma through the upregulation of SNCG mRNA. In summary, the upregulation of SNCG in blood, osteosarcoma tissue and lung metastatic tissue samples is associated with the dowregulation of miR-497, suggesting that miR-497 may be a potential marker and therapeutic target for the treatment of osteosarcoma.

Effect of baicalin on hippocampal damage in kainic acid-induced epileptic mice

The aim of the present study was to determine the effect of baicalin on the expression of miR-497 and its target B-cell lymphoma-2 (Bcl-2) in the hippocampus of kainic acid (KA)-induced epileptic mice. To establish status epilepticus (SE), 0.1 µg/5 µl KA was injected into the lateral cerebral ventricle in mice, which then received an intraperitoneal injection of baicalin (100 mg/kg) after 1 and 8 h. Hematoxylin and eosin staining was used to observe the pathological changes in morphology and neuronal apoptosis was determined by terminal transferase-mediated dUTP nick end-labeling staining. Western blot analysis was used to detect the expression of Bcl-2 and cleaved caspase-3 proteins in the hippocampus, while reverse transcription-quantitative polymerase chain reaction was used to quantify hippocampal miR-497 expression. The results showed that baicalin significantly attenuated neuronal damage and apoptosis in the hippocampus 72 h after SE. In addition, baicalin decreased SE-induced expression of miR-497 and cleaved caspase-3 protein, while upregulating the expression of Bcl-2 protein. In conclusion, the present results suggest that baicalin possesses potent antiapoptotic properties and attenuates hippocampal injury in mice after SE, which may be associated with the downregulation of miR-497 and cleaved caspase-3 and the upregulation of Bcl-2.

MicroRNA-497 inhibits cell proliferation, migration, and invasion by targeting AMOT in human osteosarcoma cells

MicroRNAs (miRNAs) have a role in the development and progression of human malignancy. The expression of miR-497 is decreased in malignant tumors, which suggests a role for miR-497 as a tumor suppressor. Angiomotin is encoded by the AMOT gene, which is a target for miR-497. Angiomotin has a role in angiogenesis, cell proliferation, and invasion in human malignancies, including osteosarcoma. However, the role of miR-497 in human osteosarcoma is unknown. This preliminary study included human osteosarcoma tissues and normal tissues from 20 patients, the osteosarcoma cell lines, MG-63, SAOS-2, U-2 OS, and the human osteoblast cell line hFOB (OB3). Western blots for angiomotin and quantitative real-time polymerase chain reaction for the expression of miR-497 and AMOT were performed. Knockdown studies were performed using RNA interference and transfection studies used miR-497 mimics. Quantitative cell migration assays were performed, and cell apoptosis was studied by flow cytometry. Osteosarcoma cells and cell lines showed reduced expression of miR-497 and increased expression of angiomotin. Transfection of osteosarcoma cells with miR-497 mimics suppressed the expression of angiomotin. Results from a dual-luciferase reporter system supported AMOT as a direct target gene of miR-497. Knockdown of AMOT using RNA interference resulted in inhibition of osteosarcoma cell proliferation, migration, and invasion. These preliminary studies support a role for miR-497 as a suppressor of AMOT gene expression in human osteosarcoma cells, resulting in suppression of tumor cell proliferation and invasion. Further studies are recommended to investigate the role of miR-497 in osteosarcoma and other malignant mesenchymal tumors.

MicroRNA-497 regulates cell proliferation in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary cancer of the liver. MicroRNA-497 (miR-497) is known to be downregulated in several types of human cancer; however, the expression, function and underlying mechanisms of miR-497 in HCC remain unclear. Therefore, the present study investigated miR-497 expression in HCC samples and HCC-derived cell lines using reverse transcription-quantitative polymerase chain reaction. The protein expression of one of the predicted common targets of miR-497, insulin-like growth factor-1 receptor (IGF-1R), was assessed using western blot analyses and immunohistochemistry. The role of miR-497 in regulating the proliferation of HCC-derived cells was also investigated in vitro and in vivo. Of 60 paired specimens from HCC patients, miR-497 was downregulated in 42 cancer specimens compared with adjacent non-cancer tissues. Western blotting and immunohistochemical analyses revealed that IGF-1R expression was significantly increased in HCC compared to control tissues. In addition, overexpression of miR-497 was observed to inhibit colony formation and tumor growth in MHCC-97H human HCC cells. Conversely, SMMC-7721 human HCC cells transfected with a miR-497 inhibitor exhibited enhanced colony formation and tumor growth. Finally, IGF-1R protein, phosphoinositide 3-kinase/Akt signaling pathway-associated proteins and cyclin pathway-associated proteins were differentially expressed between miR-497-overexpressing cells and miR-497-silenced cells. These results indicate that miR-497 may be a potentially effective gene therapy target.