A Novel miR-98 Negatively Regulates the Resistance of Endometrial Cancer Cells to Paclitaxel by Suppressing ABCC10/MRP-7

Endometrial cancer (EC) is one of the most frequent gynecological tumors, and chemoresistance is a major obstacle to improving the prognosis of EC patients. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) have recently emerged as crucial chemoresistance regulators that alter the levels of downstream target genes. Multidrug Resistance Protein 7 (MRP-7/ABCC10) is an ATP-binding cassette transporter that causes the resistance to anti-cancer drugs. The purpose of this research is to determine whether MRP-7 has a role in mediating the sensitivity of EC cells to paclitaxel and whether the expression of MRP-7 is regulated by miR-98 and lncRNA NEAT1. We reported that the levels of MRP-7 were significantly increased in EC tissues and associated with an unfavorable prognosis. Downregulation of MRP-7 in EC cells sensitized these cells to paclitaxel and reduced cell invasion. PLAUR serves as a downstream molecule of MRP-7 and facilitates paclitaxel resistance and EC cell invasiveness. Moreover, miR-98 serves as a tumor suppressor to inhibit MRP-7 expression, leading to the repression of paclitaxel resistance. Furthermore, a novel lncRNA, NEAT1, was identified as a suppressor of miR-98, and NEAT1 could upregulate MRP-7 levels by reducing the expression of miR-98. Taken together, these findings demonstrate that upregulation of MRP-7 and NEAT1, and downregulation of miR-98 have important roles in conferring paclitaxel resistance to EC cells. The modulation of these molecules may help overcome the chemoresistance against paclitaxel in EC cells.

Circular RNA 0006349 Augments Glycolysis and Malignance of Non-small Cell Lung Cancer Cells Through the microRNA-98/MKP1 Axis

Background: The involvement of dysregulated circular RNAs (circRNAs) in human diseases has been increasingly recognized. In this study, we focused on the function of a newly screened circRNA, circ_0006349, in the progression of non-small-cell lung cancer (NSCLC) and the molecules of action.

Methods: The NSCLC circRNA dataset GSE101684, microRNA (miRNA) dataset GSE29250, and mRNA dataset GSE51852 obtained from the GEO database were used to identify the differentially expressed genes in NSCLC samples. Tumor and normal tissues were collected from 59 patients with NSCLC. The expression of circ_0006349, miR-98, and MAP kinase phosphatase 1 (MKP1) in collected tissue samples and in acquired cells was determined. The binding relationships between miR-98 and circ_0006349/MKP1 were predicted and validated. Altered expression of circ_0006349, miR-98, and MKP1 was introduced in NSCLC cells to examine their roles in cell growth, apoptosis, and glycolysis.

Results: Circ_0006349 and MKP1 were upregulated, and miR-98 was poorly expressed in the collected tumor tissues and the acquired NSCLC cell lines. Circ_0006349 was identified as a sponge for miR-98 to elevate MKP1 expression. Silencing of circ_0006349 suppressed proliferation and increased apoptosis of Calu-3 and H1299 cells, and it reduced glycolysis, glucose uptake, and the production of lactate in cells. Upon circ_0006349 knockdown, further downregulation of miR-98 or upregulation of MKP1 restored the malignant behaviors of cells.

Conclusion: This research demonstrated that circ_0006349 derepressed MKP1 expression by absorbing miR-98, which augmented the proliferation and glycolysis of NSCLC cells and promoted cancer development.

SALL4 and microRNA: The Role of Let-7

SALL4 is a zinc finger transcription factor that belongs to the spalt-like (SALL) gene family. It plays important roles in the maintenance of self-renewal and pluripotency of embryonic stem cells, and its expression is repressed in most adult organs. SALL4 re-expression has been observed in different types of human cancers, and dysregulation of SALL4 contributes to the pathogenesis, metastasis, and even drug resistance of multiple cancer types. Surprisingly, little is known regarding how SALL4 expression is controlled, but recently microRNAs (miRNAs) have emerged as important regulators of SALL4. Due to the ability of regulating targets differentially in specific tissues, and recent advances in systemic and organ specific miRNA delivery mechanisms, miRNAs have emerged as promising therapeutic targets for cancer treatment. In this review, we summarize current knowledge of the interaction between SALL4 and miRNAs in mammalian development and cancer, paying particular attention to the emerging roles of the Let-7/Lin28 axis. In addition, we discuss the therapeutic prospects of targeting SALL4 using miRNA-based strategies, with a focus on the Let-7/LIN28 axis.

Aberrant expression profile of miR-32, miR-98 and miR-374 in chronic lymphocytic leukemia

INTRODUCTION

Leukemia is a malignant and progressive disease of hematopoiesis. The disease arises due to abnormal proliferation and development of white blood cells and their precursors in the blood and bone marrow. Chronic lymphoblastic leukemia (CLL) is a subtype of blood cancers, with the origin of B lymphocytes and the involvement of bone marrow, blood and lymph nodes. MicroRNAs (miRNAs) are small non-coding RNAs with pivotal roles in cellular and molecular processes related to different malignancies, including CLL. In this way, we aimed to evaluate the expression of miR-32-5p, miR-98-5p, and miR-374b-5p in CLL patients. We also investigated the signaling pathways regulated by the studied miRs and also frequently disturbed miRs in CLL.

METHODS

Blood samples were collected from 32 CLL patients from Kermanshah province, Iran and 34 age and sex-matched healthy individuals. RNA was extracted from PBMCs and then was subjected to cDNA synthesis. Using specifically designed primers and Real-Time PCR method the expression of miRNAs was detected and was statistically analyzed. Using mirPath v.3, systematic pathway enrichment analysis was performed for the three studied miRNAs here along with the frequently disturbed miRNAs in CLL.

RESULTS

The experiments indicated a significant reduction in the expression of all three miRs (p-value<0.0001) in CLL patients compared with healthy individuals. ROC analysis suggested that the three studied miRs can serve as potential biomarkers for early diagnosis of CLL. The in silico analysis suggested proteoglycans in cancer as a pathway regulated by the studied miRs and frequently dysregulated miRs in CLL.

CONCLUSION

The observed reduction in expression of miR-32-5p, miR-98-5p, and miR-374b-5p in treatment naïve CLL patients here might be suggestive of their modulatory protective role in CLL progression. Moreover, the candidate peripheral miRNAs could potentially serve as diagnostic biomarkers which warrant further investigation in a larger sample size.

Long Noncoding RNA X-Inactive Specific Transcript Regulates Neuronal Cell Apoptosis in Ischemic Stroke Through miR-98/BACH1 Axis

Long noncoding RNA X-inactive specific transcript (XIST) has been identified as a crucial regulator in neurodegenerative disorders. However, the role and mechanism of XIST in ischemic stroke remain elusive. In our study, we found that XIST expression was upregulated in both mice subjected to middle cerebral artery occlusion and oxygen-glucose deprivation (OGD)-treated neurons. Functional assays disclosed that the interference of XIST accelerated viability, and suppressed apoptosis and caspase-3 activity in OGD-treated neurons. Moreover, XIST interacted with miR-98, and miR-98 targeted BTB-to-CNC homology 1 (BACH1). miR-98 silencing or BACH1 overexpression counteracted XIST knockdown-mediated effects on cell viability and apoptosis in OGD-treated neurons. In conclusion, our data demonstrated that XIST facilitated the progression of ischemic stroke through regulating the miR-98/BACH1 axis. These findings might provide a novel therapeutic strategy for ischemic stroke treatment.

miR-98-5p inhibits gastric cancer cell stemness and chemoresistance by targeting branched-chain aminotransferases 1

AIMS

Gastric cancer stem cells (GCSCs) have been used as a therapeutic target. This study aims to estimate the role of miR-98-5p (termed miR-98) in the development of GCSCs.

MAIN METHODS

The expression of miR-98 in CD44⁺ GCSCs was verified by RT-PCR. The miR-98 was overexpressed in CD44⁺ GCSCs by Lentivirus. The ability of self-renewal, invasion, chemoresistance and tumorigenicity was detected in vitro or in vivo after overexpression of miR-98. The target genes of miR-98 were predicted and verified by luciferase reporter assays. The effects miR-98/BCAT1 signaling on the chemoresistance and tumorigenicity of CD44⁺ GCSCs were investigated in a xenograft model by rescue experiments.

KEY FINDINGS

We have shown that miR-98 was decreased in CD44⁺ GCSCs. The overexpression of miR-98 could inhibit the expression of stem-related genes and the ability of self-renewal, invasion, and tumorigenicity of GCSCs. Also, we found that miR-98 overexpression enhances the sensitivity to cisplatin treatment in vitro. Using a xenograft model, we showed that miR-98 overexpression reversed paclitaxel resistance to CD44⁺ GCSCs. Finally, we found that branched-chain aminotransferases 1 (BCAT1) is a target gene of miR-98. Overexpressed BCAT1 reversed xenograft tumor formation ability and attenuated the paclitaxel chemosensitivity induced by miR-98 downregulation. Furthermore, BCAT1 restoration affected the expression of invasion and drug resistance-related genes.

SIGNIFICANCE

This study revealed miR-98 inhibits gastric cancer cell stemness and chemoresistance by targeting BCAT1, suggesting that this miR-98/BCAT1 axis represents a potential therapeutic target in gastric cancer.

MicroRNA-98 reduces nerve growth factor expression in nicotine-induced airway remodeling

Evolving evidence suggests that nicotine may contribute to impaired asthma control by stimulating expression of nerve growth factor (NGF), a neurotrophin associated with airway remodeling and airway hyperresponsiveness. We explored the hypothesis that nicotine increases NGF by reducing lung fibroblast (LF) microRNA-98 (miR-98) and PPARγ levels, thus promoting airway remodeling. Levels of NGF, miR-98, PPARγ, fibronectin 1 (FN1), endothelin-1 (EDN1, herein referred to as ET-1), and collagen (COL1A1 and COL3A1) were measured in human LFs isolated from smoking donors, in mouse primary LFs exposed to nicotine (50 μg/ml), and in whole lung homogenates from mice chronically exposed to nicotine (100 μg/ml) in the drinking water. In selected studies, these pathways were manipulated in LFs with miR-98 inhibitor (anti-miR-98), miR-98 overexpression (miR-98 mimic), or the PPARγ agonist rosiglitazone. Compared with unexposed controls, nicotine increased NGF, FN1, ET-1, COL1A1, and COL3A1 expression in human and mouse LFs and mouse lung homogenates. In contrast, nicotine reduced miR-98 levels in LFs in vitro and in lung homogenates in vivo Treatment with anti-miR-98 alone was sufficient to recapitulate increases in NGF, FN1, and ET-1, whereas treatment with a miR-98 mimic significantly suppressed luciferase expression in cells transfected with a luciferase reporter linked to the putative seed sequence in the NGF 3'UTR and also abrogated nicotine-induced increases in NGF, FN1, and ET-1 in LFs. Similarly, rosiglitazone increased miR-98 and reversed nicotine-induced increases in NGF, FN1, and ET-1. Taken together, these findings demonstrate that nicotine-induced increases in NGF and other markers of airway remodeling are negatively regulated by miR-98.

Mechanism of miR-98 inhibiting tumor proliferation and invasion by targeting IGF1R in diabetic patients combined with colon cancer

Expression level of miR-98 in diabetic colon cancer (CRC) tissues and the regulation mechanism of colon cancer cell proliferation and invasion ability were studied. Forty patients with type 2 diabetes mellitus complicated with colon cancer, 40 colon cancer patients, and 40 patients with diabetic colonoscopy were enrolled between January 2017 and January 2018. Real-time quantitative PCR was used to detect the expression level of miR-98. After SW480 cells were transfected with miR-98 mimics or control simulants, the proliferation of cancer cells was detected by MTT assay, and the invasion ability of cancer cells was detected by Transwell cell invasion assay. The dual luciferase assay was used to detect the binding relationship between miR-98 and IGF1R. Western blot analysis was used to detect the expression of IGF1R protein in tumor tissues of patients with diabetes mellitus and colon cancer. Compared with diabetic patients, the expression level of miR-98 was decreased in colon cancer patients. Compared with tumor tissues of colon cancer patients, the expression level of miR-98 was significantly decreased in diabetic colon cancer tissues. Compared with the commonly cultured colon cancer SW480 cells, the expression level of miR-98 was significantly decreased in SW480 cells cultured under high glucose conditions. Increased expression of miR-98 inhibits colon cancer cell proliferation and invasion. miR-98 can target and bind to IGF1R and inhibit its expression level. IGF1R is upregulated in diabetic colon cancer tissue. miR-98 inhibits proliferation and invasion of diabetic colon cancer by targeting IGF1R. The expression level of miR-98 in diabetic colon cancer tissues is lower than that in colon cancer tissues. miR-98 can inhibit the proliferation and invasion of colon cancer cells by targeting the target gene IGF1R. miR-98 may be a potential biological target for the treatment of patients with diabetes and colon cancer.

MicroRNA-98 targets HMGA2 to inhibit the development of retinoblastoma through mediating Wnt/β-catenin pathway

BACKGROUND

Recently, the incidence and mortality of retinoblastoma (RB) have gradually increased. Many studies support the pivotal role of microRNAs (miRNAs) in the pathogenesis of RB. Alternation of microRNA-98 (miR-98) expression has been detected in several cancers, excluding RB. This study was designed to assess the regulatory mechanisms of miR-98 in human RB.

METHODS

RT-qPCR and Western blot analysis were used to detect miR-98 and HMGA2 expression. The effects of miR-98 were explored using the CCK-8 and Transwell assays. Dual-luciferase reporter assay was performed to confirm the relationship between miR-98 and HMGA2.

RESULTS

In RB, downregulation of miR-98 was identified. Upregulation of miR-98 inhibited proliferation, invasion and migration of RB cells. Further, HMGA2 was confirmed as a direct target gene of miR-98. And knockdown of HMGA2 suppressed the progression of RB. Moreover, upregulation of HMGA2 reversed the suppressive effects in the development of RB. In addition, miR-98 also showed suppressive effect on EMT and Wnt/β-catenin pathway.

CONCLUSION

MiR-98 targets HMGA2 to act as a tumor suppressor in RB by mediating Wnt/β-catenin pathway.

In silico identification of thiostrepton as an inhibitor of cancer stem cell growth and an enhancer for chemotherapy in non-small-cell lung cancer

Cancer stem cells (CSCs) play an important role in cancer treatment resistance and disease progression. Identifying an effective anti-CSC agent may lead to improved disease control. We used CSC-associated gene signatures to identify drug candidates that may inhibit CSC growth by reversing the CSC gene signature. Thiostrepton, a natural cyclic oligopeptide antibiotic, was the top-ranked candidate. In non-small-cell lung cancer (NSCLC) cells, thiostrepton inhibited CSC growth in vitro and reduced protein expression of cancer stemness markers, including CD133, Nanog and Oct4A. In addition, metastasis-associated Src tyrosine kinase signalling, cell migration and epithelial-to-mesenchymal transition (EMT) were all inhibited by thiostrepton. Mechanistically, thiostrepton treatment led to elevated levels of tumour suppressor miR-98. Thiostrepton combined with gemcitabine synergistically suppressed NSCLC cell growth and induced apoptosis. The inhibition of NSCLC tumours and CSC growth by thiostrepton was also demonstrated in vivo. Our findings indicate that thiostrepton, an established drug identified in silico, is an inhibitor of CSC growth and a potential enhancer of chemotherapy in NSCLC.

MicroRNA-98-HMGA2-POSTN signal pathway reverses epithelial-to-mesenchymal transition in laryngeal squamous cell carcinoma

It has been widely considered that reversing epithelial-to-mesenchymal transition (EMT) is a potential access to restrain cancer progression and therapeutic resistance. Here, we aim to uncover the novel mechanisms by which we can reverse EMT and inhibit metastasis in laryngeal squamous cell carcinoma (LSCC). We show that miR-98 is significantly reduced in both LSCC specimens and cell lines. Over-expression of miR-98 inhibits the EMT-related gene expression and metastasis and invasive behavior in LSCC in vitro, as well as reduces lung metastasis in mouse model. In the mechanistically study, miR-98 directly targets HMGA2 in mediating EMT. HMGA2 knock down by si-RNA method declines several EMT-related genes expression and LSCC migration and invasion. In parallel, overexpression of HMGA2 transforms LSCC cells to acquire stem cell-like features. Furthermore, we reveal that HMGA2-mediated EMT is closely linked with the expression of POSTN that inhibits EMT, as a tumor suppressor, by gene profiling analyses. POSTN is transcriptionally repressed by HMGA2. In clinic, the HMGA2 mRNA level is negatively correlated with the miR-98 level in LSCC patient cohort. In conclusion, our study confers a powerful signal: miR-98-HMGA-POSTN in LSCC, which is able to reverse EMT and inhibit metastasis, underlining the therapeutic potential of this signal.

Down-regulation of microRNA-98 promoted apoptosis of TNF-α stimulated human fibroblast-like synoviocytes via up-regulating IL-10

In this study, we constructed a tumor necrosis factor α (TNF-α)-induced synovial cell inflammatory model using human synoviocytes (HS) cell line to explore the function of miR-98 in rheumatoid arthritis (RA). miR-98 mimics or miR-98 inhibitor were transfected into HS cells to up-regulate or down-regulate the expression of miR-98. The proliferation and apoptosis of HS cells were determined using CCK8 assay and flow cytometry, respectively. TargetScan website was utilized to predict the targets of miR-98. Luciferase assay was carried out to verify that IL-10 is a target of miR-98. Western blot was performed to analyze the expression of IL-10, apoptosis-related and NF-κB signaling pathway-related proteins. Our results demonstrated that the expression of miR-98 was up-regulated in HS cells stimulated by TNF-α. Down-regulation of miR-98 by inhibitor in TNF-α-stimulated HS cells dramatically inhibited cell proliferation and promoted cell apoptosis compared with the miR-98 inhibitor NC group. The protein expression of Bcl-2 was declined while the levels of Bax and Bim were increased by miR-98 inhibitor in TNF-α-stimulated HS cells. IL-10 was predicted and verified as a target of miR-98. qRT-PCR and western blot results revealed that the level of IL-10 was negatively regulated by miR-98. Finally, we identified that down-regulation of miR-98 reduced the expression level of p-p65 and p-IκBα in TNF-α-stimulated HS cells. In summary, our present study demonstrated that down-regulation of miR-98 inhibited the proliferation and promoted the apoptosis of TNF-α-stimulated HS partly by targeting IL-10 and regulating NF-κB signaling pathway, insinuating miR-98 as a candidate biomarker in RA.

Overexpression of miR-98 attenuates neuropathic pain development via targeting STAT3 in CCI rat models

MicroRNA (miRNA) are significant regulators of neuropathic pain development and neuroinflammation can contribute a lot to the progression of neuropathic pain. Recently, miR-98 has been reported to be involved in various diseases. However, little is known about the role of miR-98 in neuropathic pain development and neuroinflammation. Therefore, our study was aimed to investigate the function of miR-98 in neuropathic pain via establishing a rat model using chronic constriction injury (CCI) of the sciatic nerve. Here, we observed that miR-98 was downregulated in CCI rat models. Overexpression of miR-9 was able to inhibit neuropathic pain progression. Recently, STAT3 has been reported to serve a key role in various processes, including inflammation. Interestingly, our study indicated that STAT3 was dramatically upregulated and activated in CCI rats. By using informatics analysis, STAT3 was predicted as a direct target of miR-98 and the direct correlation was confirmed. Then, miR-98 was overexpressed in CCI rats and it was found that miR-98 was able to repress neuropathic pain development via inhibiting the neuroinflammation. As displayed, interleukin 6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α) expression was obviously induced in CCI rats, while miR-98 reduced their protein levels. Finally, we found that overexpression of STAT3 reversed the inhibitory effect of miR-98 on neuropathic pain development. Taken these together, we reported that overexpression of miR-98 attenuated neuropathic pain development via targeting STAT3 in CCI rat models.

The Effect of miR-98 and miR-214 on Apoptotic and Angiogenic Pathways in Hepatocellular Carcinoma HepG2 Cells

Hepatocellular carcinoma (HCC) is one of the foremost causes of cancer related morbidity worldwide. An increasing number of studies have confirmed that microRNAs play an important role in the development, progression and metastasis of HCC. From those important miRNAs are miR-98 and miR-214. This study were conducted to explore the effect of these two miRNAs on some apoptotic and angiogenic genes namely, BCL-2, survivin, CCND1, CDC2, P53 and P21, VEGF, Hif-1α, MMP-2, MMP-9, Ang-1, Ang-2, and FGF-1. miRNAs mimics and inhibitors transfection was used to investigate the role of both studied molecules in apoptosis and angiogenesis in HepG2 cells. QRT-PCR was used for Quantitative gene and miRNA expression analyses. The study revealed that miR-98 could serve as a pro-apoptotic factor through the upregulation of P53 gene expression levels. Besides, the anti-angiogenic effect of this miRNA was evident through the down regulation of Ang-1 and FGF-1 genes. Meanwhile, miR-214 showed a pro-apoptotic role and anti-angiogenic effects. These effects were verified through the significant down regulation of BCL-2, CDC2, VEGF, Ang-1 and MMP-2. These results introduced a possible positive role played by both miR-98 and miR-214 on some pro-apoptotic and anti-angiogenic genes.

Aspirin ameliorates lung cancer by targeting the miR-98/WNT1 axis

Background

Aspirin, an anti‐inflammatory drug, has been widely investigated in the treatment of many cancer types, including colorectal, ovarian, breast, and prostate cancers. MicroRNAs (miRNAs) are the most well studied noncoding RNAs in cancers. In the current study, we were interested in defining the function of aspirin in lung cancer treatment and the related noncoding RNAs involved in this process.

Methods

The function of aspirin in lung cancer growth was evaluated by cell viability and colony formation assays. Screening of miRNAs affected by aspirin was performed through quantitative real‐time PCR. Prediction of miR‐98 targeting WNT1 was performed using online bioinformatics software and was further confirmed by luciferase reporter gene analysis. The levels of miR‐98 and WNT1 were tested through immunoblotting and quantitative real‐time PCR analysis in lung cancer cells under aspirin treatment.

Results

Cell viability was sharply suppressed in lung cancer cells with an increasing dose of aspirin. Aspirin markedly weakened the malignant colony formation ability of lung cancer cells. One out of six tumor suppressor miRNAs could be obviously regulated by aspirin in lung cancer cells. The inhibition of miR‐98 on the luciferase activities of wild‐type 3' untranslated region vectors of WNT1 was clearly revealed in lung cancer cells. Meanwhile, the inhibitor of miR‐98 increased the luciferase activities of wild‐type 3' untranslated region vectors of WNT1. After treatment with aspirin the expression of miR‐98 was induced and then its target gene, WNT1, was depressed in the cells.

Conclusion

Aspirin targets the miR‐98/WNT1 axis to ameliorate lung cancer development.

MicroRNA-98 promotes drug resistance and regulates mitochondrial dynamics by targeting LASS2 in bladder cancer cells

MicroRNA-98(miR-98) has been shown to be critical for tumorigenesis, however its involvement in bladder cancer are unclear. The present study aims to investigate the expression, biological roles and potential mechanisms of miR-98 in human bladder cancer. We found that miR-98 was upregulated in bladder urothelial carcinoma tissues compared with adjacent normal tissues. In addition, miR-98 expression was higher in bladder cancer cell lines than in uroepithelial cell line SV-HUC-1. Functional studies revealed that miR-98 mimic promoted proliferation of T24 cells while miR-98 inhibitor inhibited proliferation of BIU-87 cells. Moreover, miR-98 mimic increased cisplatin/doxorubicin resistance and inhibited apoptosis in T24 cells, while miR-98 inhibitor decreased chemoresistance and facilitated apoptosis in BIU-87 cells. Further experiments using MitoTracker and JC-1 staining showed that miR-98 could regulate mitochondrial fission/fusion balance and mitochondrial membrane potential. Western blot showed that miR-98 upregulated cyclin D1, p-Drp1 and Drp1. Using luciferase reporter assay, we demonstrated that LASS2 acted as a direct target of miR-98. LASS2 overexpression induced mitochondrial fusion and downregulated mitochondrial potential, with decreased p-Drp1 status. Additionally, LASS2 siRNA abrogated the effects of miR-98 mimic on Drp1phosphorylation and chemoresistance. We also found a negative correlation between LASS2 and miR-98 in bladder cancer tissues. In conclusion, our study demonstrates that miR-98 targets LASS2 and regulates bladder cancer chemoresistance through modulation of mitochondrial function.

The Effect of Newly Synthesized Heterosteroids on miRNA34a, 98, and 214 Expression Levels in MCF-7 Breast Cancer Cells

Hybrid anticancer drugs have emerged as great therapeutic options that can effectively overcome most obstacles facing conventional anticancer drugs. miRNAs are considered as class of non-coding RNAs that can negatively regulate protein coding gene expression. miRNA expression is commonly altered in cancer cells. The current work aimed to test the effect of new pro-apoptotic heterosteroids on some drug resistance related miRNAs expression levels (miRNA34a, 98, and 214) in MCF-7 breast cancer cells. After cell treatment with these compounds 4, 6, 7, 13, 18, 21, 22 and 24, miRNAs were extracted and subjected to reverse transcription and subsequent PCR amplification using Real Time-PCR technique. The expression levels of miR-34a, miR-98 and miR-214 were quantitatively determined. The study revealed that the expression levels of miR-34a, miR-98 and miR-214 were up-regulated upon treatment with tamoxifen, which was used as a positive control drug, as compared to control cells,. Strikingly, the levels of miR-34a, miR-98 and miR-214 expression were significantly down-regulated when treated with most of the new heterosteroids as compared to control cells. These results could indicate the promising effects of these new heterosteroids on reducing drug resistance as compared to tamoxifen drug. As well established, cells develop drug resistance to tamoxifen.

MiR-98 modulates macrophage polarization and suppresses the effects of tumor-associated macrophages on promoting invasion and epithelial-mesenchymal transition of hepatocellular carcinoma

BACKGROUND

Tumor-associated macrophages (TAMs) are generally recognized as a promoter of tumor progression. miR-98 has been shown to suppress the proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) of hepatocellular carcinoma (HCC) cells. Here, we aim to investigate the role of miR-98-mediated macrophage polarization in HCC progression.

METHODS

Human blood monocytes were isolated from healthy male donors and incubated with culture medium collected from HepG2 cells for 7 days. The phenotype of the macrophages was detected. The protein expression was detected by Western blot. Levels of cytokines secreted in culture medium were measured using the specific enzyme-linked immunosorbent assay kits. To explore the role of miR-98 in HCC-conditioned TAMs, HCC cells HepG2 and SMMC7721 were cultured with conditioned medium from HCC-conditioned TAMs that had been transfected with miR-98 mimic/inhibitor. Cell proliferation, migration and invasion assays were performed.

RESULTS

HCC-conditioned TAMs possessed M2-like phenotype, including increased protein expression of CD163 and TNF-αlow, IL-1βlow, TGF-βhigh and IL-10high phenotype. HCC-conditioned TAMs also promoted proliferation, migration, invasion and EMT of HepG2 and SMMC7721 cells. Furthermore, miR-98 modulated macrophage polarization from M2 to M1 in HCC-conditioned TAMs, as evidenced by the alteration of M1- or M2-related cytokines. Moreover, miR-98 mimic significantly suppressed the HCC-conditioned TAMs-mediated promotion of cell migration, invasion and EMT in HepG2 and SMMC7721 cells compared with negative control, whereas miR-98 inhibitor exerted reversed effects.

CONCLUSIONS

miR-98 may play a vital role in regulating macrophage polarization, thereby suppressing the TAMs-mediated promotion of invasion and EMT in HCC.

miR-98 inhibits cell proliferation and induces cell apoptosis by targeting MAPK6 in HUVECs

The aim of current study was to explore the role of microRNA (miR)-98 in atherosclerosis. Human vascular endothelial cells (HVECs) were isolated from the peripheral blood of healthy volunteers and patients with atherosclerosis. Compared with endothelial cells from the healthy control group, the expression level of mitogen activated protein kinase (MAPK)6 was significantly upregulated and miR-98 was downregulated in the endothelial cells of patients with atherosclerosis. The human umbilical vein endothelial cell line (HUVEC) was adopted to perform in vitro studies. Overexpression of miR-98 reduced the proliferation and induced the apoptosis of HUVECs, which were revealed using an MTT assay, and flow cytometry assay, respectively. The aforementioned influences of miR-98 on HUVECs were mediated by targeting MAPK6, which was verified using luciferase assays. Additionally, the overexpression of miR-98 reduced the protein level of apoptosis regulator Bcl-2 and MAPK6; however, it induced the protein expression of caspase-3 and apoptosis regulator Bax. In conclusion, these findings demonstrate that miR-98 is an important regulator of atherosclerosis, suggesting that miR-98 may be a potential therapeutic target for the treatment of atherosclerosis.

MicroRNA-98 inhibits the cell proliferation of human hypertrophic scar fibroblasts via targeting Col1A1

Background

Hypertrophic scarring (HS) is a severe disease, and results from unusual wound healing. Col1A1 could promote the hypertrophic scar formation, and the expression of Col1A1 in HS tissue was markedly higher than that in the normal. In present study, we aimed to identify miRNAs as post-transcriptional regulators of Col1A1 in HS.

Methods

MicroRNA-98 was selected as the key miRNA comprised in HS. The mRNA levels of miR-98 in HS tissues and the matched normal skin tissues were determined by qRT-PCR. MTT and flow cytometry were used to determine the influence of miR-98 on cell proliferation and apoptosis of HSFBs, respectively. Col1A1 was found to be the target gene of miR-98 using luciferase reporter assay. Luciferase assay was performed to determine the relative luciferase activity in mimic NC, miR-98 mimic, inhibitor NC and miR-98 inhibitor with Col1A13′-UTR wt or Col1A13′-UTR mt reporter plasmids. The protein expression of Col1A1 in HSFBs after transfection with mimic NC, miR-98 mimic, inhibitor NC and miR-98 inhibitor were determined by western blotting.

Results

The mRNA level of miR-98 in HS tissues was much higher than that in the control. Transfection of HSFBs with a miR-98 mimic reduced the cell viability of HSFBs and increased the apoptosis portion of HSFBs, while inhibition of miR-98 increased cell viability and decreased apoptosis portion of HSFBs. miR-98 inhibitor increased the relative luciferase activity significantly when cotransfected with the Col1A1-UTR reporter plasmid, while the mutant reporter plasmid abolished the miR-98 inhibitor-mediated increase in luciferase activity. Western blotting revealed that overexpression of miR-98 decreased the expression of Col1A1.

Conclusions

Overexpression of miR-98 repressed the proliferation of HSFBs by targeting Col1A1.

Curcumin Inhibits LIN-28A through the Activation of miRNA-98 in the Lung Cancer Cell Line A549

Metastasis is common in lung cancer and is associated with poor clinical outcomes and increased mortality. Curcumin is a natural anti-cancer agent that inhibits the metastasis of various cancers by modulating the expression of micro (mi) RNAs such as miR-98, which acts as a tumor suppressor. This study investigated the effect of curcumin on miR-98 expression and in vitro cell line growth and invasiveness in lung cancer. Curcumin treatment enhanced the expression of miR-98 and reduced that of the miR-98 target gene LIN28A as well as matrix metalloproteinase (MMP) 2 and MMP9 in vitro and in vivo. MiR-98 overexpression suppressed lung cancer cell migration and invasion by inhibiting LIN28A-induced MMP2 and MMP9 expression. Meanwhile, LIN28A level was downregulated by overexpression of miR-98 mimic. Induction of miR-98 by curcumin treatment suppressed MMP2 and MMP9 by targeting LIN28A. These findings provide insight into the mechanisms by which curcumin suppresses lung cancer cell line growth in vitro and in vivo and invasiveness in vitro.

miR-98 inhibits expression of TWIST to prevent progression of non-small cell lung cancers

Evidence is mounting that micro RNAs (miRNAs) play a critical role in tumor development. However, the role of miRNAs in lung cancer progression remains largely unknown. Herein, we found that miR-98 significantly impaired in patients with non-small cell lung cancers (NSCLC) and was a novel regulator of NSCLC progression. Patients with high miR-98 expression had a longer overall survival than with low miR-98 expression (p=0.0495). miR-98 expression level inversely correlated with TWIST mRNA level in 71 clinical tissue specimens of NSCLC (p<0.01). Luciferase assay demonstrated that miR-98 interacted binding sites in the TWIST 3'-UTR and reduced expression of TWIST, resulting in repression of cell migration and invasion via impeding TWIST-mediated EMT. Furthermore, introduction of synthetic miR-98 caused growth arrest by inactivating TWIST-Akt-CDK4/CDK6. Meanwhile, miR-98 mimic induced apoptosis by targeting TWIST-Akt axis. In a conclusion, these observations imply that miR-98 may act as a tumor suppressor in NSCLC to decelerate NSCLC aggressiveness by inhibiting TWIST expression.

SNHG16 contributes to breast cancer cell migration by competitively binding miR-98 with E2F5

Long noncoding RNAs (lncRNAs) have been proved to play important roles in cellular processes of cancer, including the development, proliferation, and migration of cancer cells. In the present study, we demonstrated small nucleolar RNA host gene 16 (SNHG16) as an oncogene on cell migration in breast cancer. Expression levels of SNHG16 were found to be frequently higher in breast cancer tissues than in the paired noncancerous tissues. Gain- and loss-of-function studies proved that SNHG16 significantly promoted breast cancer cell migration. We predicted SNHG16 as a competitive endogenous RNA (ceRNA) of E2F transcription factor 5 protein (E2F5) via competition for the shared miR-98 through bioinformatics analysis, and proved this regulation using relative quantitative real-time PCR (qRT-PCR), western blot, RNA immunoprecipitation (RIP) assay and luciferase reporter assay. In addition, we identified a positive correlation between SNHG16 and E2F5 in breast cancer tissues. Furthermore, we demonstrated that forced expression of miR-98 could partially abrogate SNHG16-mediated increase of breast cancer cells migration, suggesting that SNHG16 promoted cell migration in a miR-98 dependent manner. Taken together, our findings indicated that SNHG16 induces breast cancer cell migration by competitively binding miR-98 with E2F5, and SNHG16 can serve as a potential therapeutic target for breast cancer treatment.

MicroRNA-98 Attenuates Cell Migration and Invasion in Glioma by Directly Targeting Pre-B Cell Leukemia Homeobox 3

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults. The extraordinary invasion of human GBM into adjacent normal brain tissues contributes to treatment failure. However, the mechanisms that control this process remain poorly understood. Increasing evidence has demonstrated that microRNAs are strongly implicated in the migration and invasion of GBM. In this study, we found that microRNA-98 (miR-98) was markedly downregulated in human glioma tissues and cell lines. Functional experiments indicated that restored expression of miR-98 attenuated glioma cell invasion and migration, whereas depletion of miR-98 promoted glioma cell invasion and migration. Subsequent investigation showed that pre-B-cell leukemia homeobox 3 (PBX3), an important transcription factor that controls tumor invasion, was a direct and functional target of miR-98 in GBM cells. Consistently, an orthotopic mouse model also demonstrated the suppressive effects of miR-98 overexpression on tumor invasion and PBX3 expression. Silencing of PBX3 using small interfering RNA inhibited the migratory and invasive capacities of glioma cells, whereas reintroduction of PBX3 into glioma cells reversed the anti-invasive function of miR-98. Furthermore, depletion of PBX3 phenocopied the effects of miR-98 overexpression in vivo. Finally, quantitative real-time polymerase chain reaction results showed that miR-98 was negatively correlated with PBX3 expression in 24 glioma tissues. Thus, we propose that PBX3 modulation by miR-98 has an important role in regulating GBM invasion and may serve as therapeutic target for GBM.

miR-98 inhibits hepatocellular carcinoma cell proliferation via targeting EZH2 and suppressing Wnt/β-catenin signaling pathway

Hepatocellular carcinoma (HCC) is a highly aggressive solid malignancy in the word. Aberrant microRNA (miRNA) expression is involved in human diseases including cancer. In the current study, we explore the function of miR-98 in HCC cell proliferation. We found that expression level of miR-98 was significantly decreased in HCC tissues and cells lines compared with adjacent non-tumor issues and human hepatic cell line LO2. Increased expression of miR-98 suppressed HCC cell proliferation and arrested HCC cell cycle in G0/G1 phase. While, suppressed expression of miR-98 showed the opposite effect. Bioinformatics analysis revealed EZH2, a putative tumor promoter as a potential target of miR-98. Additionally, luciferase reporter assay revealed that miR-98 directly binds to the 3'-untranslated region (3'-UTR) of EZH2 mRNA. Furthermore, we demonstrated that miR-98 could reduce the Wnt/β-catenin signal pathway by suppressing EZH2 directly. Moreover, inhibition of EZH2 abrogated the effect of miR-98 inhibitor on HCC cell proliferation. Taken together, these results suggested that miR-98 functioned as a potential tumor suppressor by regulating Wnt/β-catenin signal pathway through direct suppression of EZH2 expression and might sever as a potential therapeutic target for HCC patients.

Peroxisome Proliferator-Activated Receptor γ and microRNA 98 in Hypoxia-Induced Endothelin-1 Signaling

Endothelin-1 (ET-1) plays a critical role in endothelial dysfunction and contributes to the pathogenesis of pulmonary hypertension (PH). We hypothesized that peroxisome proliferator-activated receptor γ (PPARγ) stimulates microRNAs that inhibit ET-1 and pulmonary artery endothelial cell (PAEC) proliferation. The objective of this study was to clarify molecular mechanisms by which PPARγ regulates ET-1 expression in vitro and in vivo. In PAECs isolated from patients with pulmonary arterial hypertension, microRNA (miR)-98 expression was reduced, and ET-1 protein levels and proliferation were increased. Similarly, hypoxia reduced miR-98 and increased ET-1 levels and PAEC proliferation in vitro. In vivo, hypoxia reduced miR-98 expression and increased ET-1 and proliferating cell nuclear antigen (PCNA) levels in mouse lung, derangements that were aggravated by treatment with the vascular endothelial growth factor receptor antagonist Sugen5416. Reporter assays confirmed that miR-98 binds directly to the ET-1 3'-untranslated region. Compared with littermate control mice, miR-98 levels were reduced and ET-1 and PCNA expression were increased in lungs from endothelial-targeted PPARγ knockout mice, whereas miR-98 levels were increased and ET-1 and PCNA expression was reduced in lungs from endothelial-targeted PPARγ-overexpression mice. Gain or loss of PPARγ function in PAECs in vitro confirmed that alterations in PPARγ were sufficient to regulate miR-98, ET-1, and PCNA expression. Finally, PPARγ activation with rosiglitazone regimens that attenuated hypoxia-induced PH in vivo and human PAEC proliferation in vitro restored miR-98 levels. The results of this study show that PPARγ regulates miR-98 to modulate ET-1 expression and PAEC proliferation. These results further clarify molecular mechanisms by which PPARγ participates in PH pathogenesis and therapy.

miR-98 functions as a tumor suppressor in salivary adenoid cystic carcinomas

Purpose

miR-98, a member of the let-7 family of microRNAs, is downregulated in many malignant tumors and has been correlated with tumor progression. However, the roles of miR-98 in salivary adenoid cystic carcinomas (SACCs) are still unclear. Thus, we explored the role of miR-98 in the pathogenesis of SACCs.

Methods

Reverse transcription-polymerase chain reaction was used to quantify miR-98 expression in SACC cell lines as well as in the primary tumors and adjacent tissues. Target gene prediction was carried out using softwares such as miRanda, PicTar, and TargetScan, and the neuroblastoma RAS viral oncogene homologue (N-RAS) was chosen as a potential target gene. Subsequently, the regulatory role of miR-98 on N-RAS expression was examined by Western blotting and immunofluorescence assays. N-RAS expression was detected in SACC tissues and SACC cell lines using immunohistochemistry and Western blot, respectively. Furthermore, the associations between N-RAS expression and clinicopathological features were analyzed. Finally, the effects of miR-98 on the proliferation and metastasis of SACC cell lines were determined.

Results

miR-98 was downregulated in primary tissues and ACC-M cells. Meanwhile, N-RAS expression was significantly higher in SACC tissues than that in the adjacent tissues, and its overexpression was significantly associated with the clinical stage and tumor size. In addition, the overexpression of miR-98 in ACC-M cells inhibited cell proliferation, invasion, and migration in vitro. It also significantly decreased the expression of N-RAS and inhibited signaling through the PI3K/AKT and MAPK/ERK pathways.

Conclusion

These results indicate that miR-98 possibly acts as a tumor suppressor in SACC by negatively regulating the oncogene N-RAS.

High glucose concentration induces endothelial cell proliferation by regulating cyclin-D2-related miR-98

Cyclin D2 is involved in the pathology of vascular complications of type 2 diabetes mellitus (T2DM). This study investigated the role of cyclin‐D2‐regulated miRNAs in endothelial cell proliferation of T2DM. Results showed that higher glucose concentration (4.5 g/l) significantly promoted the proliferation of rat aortic endothelial cells (RAOECs), and significantly increased the expression of cyclin D2 and phosphorylation of retinoblastoma 1 (p‐RB1) in RAOECs compared with those under low glucose concentration. The cyclin D2‐3′ untranslated region is targeted by miR‐98, as demonstrated by miRNA analysis software. Western blot also confirmed that cyclin D2 and p‐RB1 expression was regulated by miR‐98. The results indicated that miR‐98 treatment can induce RAOEC apoptosis. The suppression of RAOEC growth by miR‐98 might be related to regulation of Bcl‐2, Bax and Caspase 9 expression. Furthermore, the expression levels of miR‐98 decreased in 4.5 g/l glucose‐treated cells compared with those treated by low glucose concentration. Similarly, the expression of miR‐98 significantly decreased in aortas of established streptozotocin (STZ)‐induced diabetic rat model compared with that in control rats; but cyclin D2 and p‐RB1 levels remarkably increased in aortas of STZ‐induced diabetic rats compared with those in healthy control rats. In conclusion, this study demonstrated that high glucose concentration induces cyclin D2 up‐regulation and miR‐98 down‐regulation in the RAOECs. By regulating cyclin D2, miR‐98 can inhibit human endothelial cell growth, thereby providing novel therapeutic targets for vascular complication of T2DM.

Restoration of miR-98 relieves the inhibitory effect of nicotine on the differentiation of P19 cells into cardiomyocytes

OBJECTIVE

To study whether miR-98 participates in the effects of nicotine on myocardial differentiation.

RESULTS

By western blot, MTT and flow cytometry assays, we found that nicotine suppresses P19 cell differentiation into cardiomyocytes and apoptosis, and promotes proliferation, while restoration of miR-98 relieves the inhibitory effect of nicotine on the P19 cell differentiation. By target prediction analysis and luciferase reporter assay, we observed that miR-98 inhibits the protein expression of Wnt1 by directly acting on the 3'-UTR of Wnt1 mRNA. We assumed that the effect of miR-98 on Wnt1 might alter the activity of the Wnt1/β-catenin signaling pathway and be associated with myocardial differentiation. In summary, nicotine restrains differentiation of P19 cells into cardiomyocytes and decreases the level of miR-98.

CONCLUSIONS

Restoration of miR-98 relieves the inhibitory effect of nicotine on differentiation of P19 cells via targeting the 3'-UTR of Wnt1, which offers novel insights into our understanding of underlying molecular mechanisms of congenital heart defects.

MiR-98 inhibits cell proliferation and invasion of non-small cell carcinoma lung cancer by targeting PAK1

A family of small non-coding RNAs, ~22 nt in length, known as microRNAs (miRNAs), regulating ~30% of all human gene expression, have been reported to be involved in the pathogenesis of a number of types of cancers, including non-small cell carcinoma lung cancer (NSCLC). P21-activated protein kinase 1 (PAK1) is a clinical biomarker of Non-small carcinoma lung cancer. Here, we found that miR-98 is down-regulated, whereas PAK1 is highly expressed in NSCLC tissues and cells. We demonstrated that miR-98 directly targets the 3'UTR of PAK1 and down-regulates its expression at the mRNA and protein level. Also, miR-98 inhibited and PAK1 stimulated proliferation, migration, invasion and apoptosis of NSCLC cells. In agreement, PAK1 over-expression counteracted the inhibitory effect of miR-98. This current study suggests that exogenous miR-98 may serve as novel potential maker for NSCLC therapy.

miR-98 suppresses tumor cell growth and metastasis by targeting IGF1R in oral squamous cell carcinoma

Increasing evidences indicate that dysregulation of miRNAs contributes to the pathogenesis of oral squamous cell carcinoma (OSCC). However, little is known about the potential role of miR-98 in OSCC. Here, we found that miR-98 was downregulated in OSCC tissues and cell lines. Overexpression of miR-98 inhibited proliferation, colony formation, migration, and invasion of OSCC cells. IGF1R was identified as the potential target of miR-98 using dual luciferase assay, qRT-PCR and western blot. Furthermore, restoration of IGF1R remarkably reversed the tumor-suppressive effects of miR-98 on OSCC cells. Moreover, miR-98 expression was inversely correlated with IGF1R expression in 19 cases of OSCC. These findings suggest that miR-98 inhibits cancer cell growth and metastasis by direct targeting IGF1R, implicating miR-98 as a novel potential therapeutic target for OSCC.

miR-98 targets ITGB3 to inhibit proliferation, migration, and invasion of non-small-cell lung cancer

Background

Accumulating evidence has emphasized causative links between aberrant microRNA (miR) expression patterns and cancer development. Abnormally expressed miRNA-98 (miR-98) was found in certain types of human cancers. The biological roles of miR-98 in lung cancer, however, remain largely undefined.

Methods

We evaluated the expression of miR-98 in normal lung tissues, lung cancer tissues, normal human bronchial epithelial cells, and lung cancer cells using quantitative real-time polymerase chain reaction. Effect of miR-98 on proliferation of lung cancer cells was investigated using MTT assay and colony formation assay. Transwell assay was used to assess the effects of miR-98 on migration and invasion of lung cancer cells. Whether miR-98 targets the 3′-untranslated region (3′-UTR) of integrin β3 (ITGB3) coding gene ITGB3 mRNA was ascertained using luciferase reporter assay. Finally, we transplanted miR-98 expressing A549 cells into nude mice to observe the effect of miR-98 on tumor growth in vivo.

Results

We confirmed that miR-98 was frequently low expressed in lung cancer tissues and human lung cancer cells. Reintroduction of miR-98 into lung cancer cells inhibited cell proliferation, migration, and invasion in vitro and suppressed tumor formation in a nude mouse model. Furthermore, we identified that miR-98 exerted inhibitory roles by directly binding to 3′-UTR of ITGB3 mRNA, thus negatively regulated the expression of ITGB3. Interestingly, upon restoring the expression of ITGB3, the effect of miR-98 on cell proliferation was partially reversed.

Conclusion

Our findings suggest that miR-98 prevents proliferation, migration, and invasion of lung cancer cells by directly binding to the 3′-UTR of ITGB3 mRNA and could be a promising treatment option in anticancer therapy.

Over-expression of miR-98 in FFPE tissues might serve as a valuable source for biomarker discovery in breast cancer patients

The miR-98 is thought to be associated with various cancers. This study was to evaluate the potential predictive value of miR-98 expression in formalin-fixed paraffin-embedded tissue of breast cancer patients. The expression levels of miR-98 were examined in 98 breast cancer patients and 40 cancer-free controls using real-time quantitative PCR. The comparison of miR-98 expression levels between patient and control was performed using the Mann-Whitney test. The miR-98 showed higher expression levels in breast cancer patients compared with cancer free controls (p<0.01). The expression levels of miR-98 were highly correlated with miR24/93/378 in breast cancer patients. The miR-98 exhibited great capability of discriminating between cancer patients and controls by the Receiver-operator characteristic (ROC) curve analysis. The miR-98 was found highly correlated with breast cancer by Univariable logistic regression analysis. These results suggest that over-expression of miR-98 in formalin-fixed paraffin-embedded tissues might serve as a valuable source for biomarker discovery in breast cancer patients.