Exosomal MiR‐500a‐3p promotes cisplatin resistance and stemness via negatively regulating FBXW7 in gastric cancer

Chemoresistance has been a major challenge in advanced gastric cancer (GC) therapy. Exosomal transfer of oncogenic miRNAs implicates important effects in mediating recipient cell chemoresistance by transmitting active molecules. In this study, we found that microRNA‐500a‐3p was highly expressed in cisplatin (DDP) resistant GC cells (MGC803/DDP and MKN45/DDP) and their secreted exosomes than that in the corresponding parental cells. MGC803/DDP‐derived exosomes enhance DDP resistance and stemness properties of MGC803 recipient cells via exosomal delivery of miR‐500a‐3p in vitro and in vivo through targeting FBXW7. However, reintroduction of FBXW7 in MGC803 cells reverses miR‐500a‐3p‐mediated DDP resistance as well as stemness properties. Furthermore, elevated miR‐500a‐3p in the plasma exosomes of GC patients is correlated with DDP resistance and thereby results in poor progression‐free prognosis. Our finding highlights the potential of exosomal miR‐500a‐3p as an potential modality for the prediction and treatment of GC with chemoresistance.     

Exosomes from miR‐20b‐3p‐overexpressing stromal cells ameliorate calcium oxalate deposition in rat kidney

Hyperoxaluria‐induced calcium oxalate (CaOx) deposition is the key factor in kidney stone formation, for which adipose‐derived stromal cells (ADSCs) have been used as a therapeutic treatment. Studies revealed that miR‐20b‐3p is down‐regulated in hypercalciuric stone‐forming rat kidney. To investigate whether ADSC‐derived miR‐20b‐3p‐enriched exosomes protect against kidney stones, an ethylene glycol (EG)‐induced hyperoxaluria rat model and an in vitro model of oxalate‐induced NRK‐52E cells were established to explore the protective mechanism of miR‐20b‐3p. The results showed that miR‐20b‐3p levels were decreased following hyperoxaluria in the urine of patients and in kidney tissues from animal models. Furthermore, treatment with miR‐20b‐3p‐enriched exosomes from ADSCs protected EG‐induced hyperoxaluria rats, and cell experiments confirmed that co‐culture with miR‐20b‐3p‐enriched exosomes alleviated oxalate‐induced cell autophagy and the inflammatory response by inhibiting ATG7 and TLR4. In conclusion, ADSC‐derived miR‐20b‐3p‐enriched exosomes protected against kidney stones by suppressing autophagy and inflammatory responses.     

MiR‐9 promotes angiogenesis of endothelial progenitor cell to facilitate thrombi recanalization via targeting TRPM7 through PI3K/Akt/autophagy pathway

Endothelial progenitor cells (EPCs) have emerged as a promising therapeutic choice for thrombi recanalization. However, this role of EPCs is confined by some detrimental factors. The aim of this study was to explore the role of the miR‐9‐5p in regulation of the proliferation, migration and angiogenesis of EPCs and the subsequent therapeutic role in thrombosis event. Wound healing, transwell assay, tube formation assay and in vivo angiogenesis assay were carried out to measure cell migration, invasion and angiogenic abilities, respectively. Western blot was performed to elucidate the relationship between miR‐9‐5p and TRPM7 in the autophagy pathway. It was found that miR‐9‐5p could promote migration, invasion and angiogenesis of EPCs by attenuating TRPM7 expression via activating PI3K/Akt/autophagy pathway. In conclusion, miR‐9‐5p, targets TRPM7 via the PI3K/Ak/autophagy pathway, thereby mediating cell proliferation, migration and angiogenesis in EPCs. Acting as a potential therapeutic target, miR‐9‐5p may play an important role in the prognosis of DVT.     

MicroRNA‐198 inhibition of HGF/c‐MET signaling pathway overcomes resistance to radiotherapy and induces apoptosis in human non–small‐cell lung cancer

Non–small‐cell lung cancer (NSCLC) is the most common cause of death from cancer worldwide. MicroRNAs (miRNAs) are a group of important regulators in NSCLC, including miR‐198. However, the underlying molecular mechanisms of miR‐198 involvement in intrinsic resistance to radiotherapy in NSCLC remain to be elucidated. In this study, to investigate the clinical significance of miR‐198 in NSCLC in relation to the response to radiotherapy, we determined the expression patterns of miR‐198 between responders and nonresponders after 2 months of radiotherapy and found that decreased expressions of miR‐198 were associated with radiotherapy resistance. In addition, we altered the endogenous miR‐198 using mimics or inhibitors to examine the effects of miR‐198 on 4‐Gy–irradiated A549 and SPCA‐1 cells in vitro. Upregulating miR‐198 was shown to inhibit cell proliferation, migration, and invasion and induce apoptosis. MiR‐198 inhibition produced a reciprocal result. PHA665752, a selective small‐molecule c‐Met inhibitor, potently inhibited hepatocyte growth factor (HGF)‐stimulated and constitutive c‐Met phosphorylation and rescued 4‐Gy–irradiated A549 and SPCA‐1 cells from miR‐198 inhibition. Most importantly, we established tumor xenografts of 4‐Gy–irradiated A549 and SPCA‐1 cells in nude mice and found that miR‐198 could suppress tumor formation. Hence, our data delineates the molecular pathway by which miR‐198 inhibits NSCLC cellular proliferation and induces apoptosis following radiotherapy, providing a novel target aimed at improving the radiotherapeutic response in NSCLC.     

LncRNA MST1P2/miR‐133b axis affects the chemoresistance of bladder cancer to cisplatin‐based therapy via Sirt1/p53 signaling

Although bladder cancer is commonly chemosensitive to standard first‐line therapy, the acquisition of the resistance to cisplatin (DDP)‐based therapeutic regimens remains a huge challenge. Noncoding RNAs (ncRNAs), including long noncoding RNAs (lncRNAs) and microRNAs, have been reported to play a critical role in cancer resistance to DDP. Here, we attempted to provide a novel mechanism by which the resistance of bladder cancer to DDP treatment could be modulated from the perspective of ncRNA regulation. We demonstrated that lncRNA MST1P2 (lnc‐MST1P2) expression was dramatically upregulated, whereas miR‐133b expression was downregulated in DDP‐resistant bladder cancer cell lines, SW 780/DDP and RT4/DDP. Lnc‐MST1P2 and miR‐133b negatively regulated each other via targeting miR‐133b. Both lnc‐MST1P2 silence and miR‐133b overexpression could resensitize DDP‐resistant bladder cancer cells to DDP treatment. More important, miR‐133b could directly target the Sirt1 3′‐untranslated region to inhibit its expression. Inc‐MST1P2/miR‐133b axis affected the resistance of bladder cancer cells to DDP via Sirt1/p53 signaling. In conclusion, MST1P2 serves as a competing endogenous RNA for miR‐133b to counteract miR‐133b‐induced suppression on Sirt1, therefore enhancing the resistance of bladder cancer cells to DDP. MST1P2/miR‐133b axis affects the resistance of bladder cancer cells to DDP via downstream Sirt1/p53 signaling.     

Hsa_circ_0092276 promotes doxorubicin resistance in breast cancer cells by regulating autophagy via miR-348/ATG7 axis

Previous study has confirmed that hsa_circ_0092276 is highly expressed in doxorubicin (DOX)-resistant breast cancer cells, indicating that hsa_circ_0092276 may be involved in regulating the chemotherapy resistance of breast cancer. Here we attempted to investigate the biological role of hsa_circ_0092276 in breast cancer. We first constructed DOX-resistant breast cancer cells (MCF-7/DOX and MDA-MB-468/DOX). The 50% inhibiting concentration of MCF-7/DOX and MDA-MB-468/DOX cells was significantly higher than that of their parental breast cancer cells, MCF-7 and MDA-MB-46. MCF-7/DOX and MDA-MB-468/DOX cells also exhibited an up-regulation of drug resistance-related protein MDR1. Compared with MCF-7 and MDA-MB-46 cells, hsa_circ_0092276 was highly expressed in MCF-7/DOX and MDA-MB-468/DOX cells. Hsa_circ_0092276 overexpression enhanced proliferation and the expression of LC3-II/LC3-I and Beclin-1, and repressed apoptosis of breast cancer cells. The effect of hsa_circ_0092276 up-regulation on breast cancer cells was abolished by 3-methyladenine (autophagy inhibitor). Hsa_circ_0092276 modulated autophagy-related gene 7 (ATG7) expression via sponging miR-384. Hsa_circ_0092276 up-regulation promoted autophagy and proliferation, and repressed apoptosis of breast cancer cells, which was abolished by miR-384 overexpression or ATG7 knockdown. In addition, LV-circ_0092276 transfected MCF-7 cell transplantation promoted autophagy and tumor growth of breast cancer in mice. In conclusion, our data demonstrate that hsa_circ_0092276 promotes autophagy and DOX resistance in breast cancer by regulating miR-348/ATG7 axis. Thus, this article highlights a novel competing endogenous RNA circuitry involved in DOX resistance in breast cancer.     

microRNA‐145‐3p inhibits non‐small cell lung cancer cell migration and invasion by targeting PDK1 via the mTOR signaling pathway

The mammalian target of rapamycin (mTOR) pathway is dysregulated in more than 50% of all human malignancies and is a major target in cancer treatment. In this study, we explored the underlying mechanism involving microRNA‐145‐3p (miR‐145‐3p) in the development and progression of non‐small cell lung cancer (NSCLC) by targeting PDK1 via the mTOR signaling pathway. NSCLC tissues and adjacent normal tissues were obtained from 83 NSCLC patients. miR‐145‐3p, PDK1, and mTOR levels were determined by quantitative real‐time polymerase chain reaction (qRT‐PCR) and immunohistochemistry. Human NSCLC cell lines A549 and H1299 were transfected with miR‐145‐3p and siPDK1 to confirm the effect of miR‐145‐3p and PDK1 on NSCLC cells in vitro. Cell growth was evaluated by a CCK8 assay. Cell motility and chemotaxis analysis were determined by the scratch test and chemotaxis assay, respectively. The protein levels of PDK1 and mTOR were measured using the western blotting. Results showed lower level of miR‐145‐3p and higher levels of PDK1 and mTOR in NSCLC tissues compared to the adjacent normal tissues. In vitro results showed that cell growth, cell motility, and chemotaxis were all inhibited in cells transfected with miR‐145‐3p and those transfected with siPDK. Additionally, dual luciferase reporter gene assay helped confirmed that PDK1 is a target of miR‐145. Finally, levels of PDK1, mTOR, and phosphorylated‐mTOR were lower in cells transfected with miR‐145‐3p as well as those with siPDK1. These findings indicate that miR‐145‐3p may inhibit cell growth, motility, and chemotaxis in NSCLC by targeting PDK1 through suppressing the mTOR pathway.     

MiR‐34b‐3p represses cell proliferation,cell cycle progression and cell apoptosis in non‐small‐cell lung cancer (NSCLC) by targeting CDK4

Lung cancer is the most common incident cancer, with a high mortality worldwide, and non‐small‐cell lung cancer (NSCLC) accounts for approximately 85% of cases. Numerous studies have shown that the aberrant expression of microRNAs (miRNAs) is associated with the development and progression of cancers. However, the clinical significance and biological roles of most miRNAs in NSCLC remain elusive. In this study, we identified a novel miRNA, miR‐34b‐3p, that suppressed NSCLC cell growth and investigated the underlying mechanism. miR‐34b‐3p was down‐regulated in both NSCLC tumour tissues and lung cancer cell lines (H1299 and A549). The overexpression of miR‐34b‐3p suppressed lung cancer cell (H1299 and A549) growth, including proliferation inhibition, cell cycle arrest and increased apoptosis. Furthermore, luciferase reporter assays confirmed that miR‐34b‐3p could bind to the cyclin‐dependent kinase 4 (CDK4) mRNA 3′‐untranslated region (3′‐UTR) to suppress the expression of CDK4 in NSCLC cells. H1299 and A549 cell proliferation inhibition is mediated by cell cycle arrest and apoptosis with CDK4 interference. Moreover, CDK4 overexpression effectively reversed miR‐34‐3p‐repressed NSCLC cell growth. In conclusion, our findings reveal that miR‐34b‐3p might function as a tumour suppressor in NSCLC by targeting CDK4 and that miR‐34b‐3p may, therefore, serve as a biomarker for the diagnosis and treatment of NSCLC.     

MiR‐376a suppresses the proliferation and invasion of non‐small‐cell lung cancer by targeting c‐Myc

It has been reported that miR‐376a is involved in the formation and progression of several types of cancer. However, the expression and function of miR‐376a is still unknown in non‐small cell lung carcinomas (NSCLC). In this study, the expression of miR‐376a in NSCLC tissues and cell lines were examined by real‐time PCR, the effects of miR‐376a on cell proliferation, apoptosis and invasion were evaluated in vitro. Luciferase reporter assay was performed to identify the targets of miR‐376a. The results showed that miR‐376a was significantly downregulated in NSCLC tissues and cell lines. Restoration of miR‐376a in NSCLC cell line A549 significantly inhibited cell proliferation, increased cell apoptosis and suppressed cell invasion, compared with control‐transfected A549 cells. Luciferase reporter assay showed that c‐Myc, an oncogene that regulating cell survival, angiogenesis and metastasis, was a direct target of miR‐376a. Over‐expression of miR‐376a decreased the mRNA and protein levels of c‐Myc in A549 cells. In addition, upregulation of c‐Myc inhibited miR‐376a‐induced inhibition of cell proliferation and invasion in A549 cells. Therefore, our results indicate a tumor suppressor role of miR‐376a in NSCLC by targeting c‐Myc. miR‐376a may be a promising therapeutic target for NSCLC.     

Exosomes transmit T790M mutation‐induced resistance in EGFR‐mutant NSCLC by activating PI3K/AKT signalling pathway

Emerging evidence has shown that exosomes derived from drug‐resistant tumour cells are able to horizontally transmit drug‐resistant phenotype to sensitive cells. However, whether exosomes shed by EGFR T790M‐mutant–resistant NSCLC cells could transfer drug resistance to sensitive cells has not been investigated. We isolated exosomes from the conditioned medium (CM) of T790M‐mutant NSCLC cell line H1975 and sensitive cell line PC9. The role and mechanism of exosomes in regulating gefitinib resistance was investigated both in vitro and in vivo. Exosome‐derived miRNA expression profiles from PC9 and H1975 were analysed by small RNA sequencing and confirmed by qRT‐PCR. We found that exosomes shed by H1975 could transfer gefitinib resistance to PC9 both in vitro and in vivo through activating PI3K/AKT signalling pathway. Small RNA sequencing and RT‐PCR confirmed that miR‐3648 and miR‐522‐3p were the two most differentially expressed miRNAs and functional study showed that up‐regulation of miR‐522‐3p could induce gefitinib resistance in PC9 cell. The findings of our study reveal an important mechanism of acquired resistance to EGFR‐TKIs in NSCLC.     

miR‐150‐5p suppresses the stem cell‐like characteristics of glioma cells by targeting the Wnt/β‐catenin signaling pathway

Glioma is the most common brain tumor malignancy with high mortality and poor prognosis. Emerging evidence suggests that cancer stem cells are the key culprit in the development of cancer. MicroRNAs have been reported to be dysregulated in many cancers, while the mechanism underlying miR‐150‐5p in glioma progression and proportion of stem cells is unclear. The expression levels of miR‐150‐5p and catenin beta 1 (CTNNB1, which encodes β‐catenin) were measured by quantitative real‐time polymerase chain reaction (qRT‐PCR) and western blot. The expression levels of downstream genes of the Wnt/β‐catenin pathway and stem cell markers were detected by qRT‐PCR. Tumorigenesis was investigated by cell viability, colony formation, and tumor growth in vitro and in vivo. The interaction between miR‐150‐5p and β‐catenin was explored via bioinformatics analysis and luciferase activity assay. We found that miR‐150‐5p was downregulated in glioma and its overexpression inhibited cell proliferation, colony formation, and tumor growth. Moreover, miR‐150‐5p directly suppressed CTNNB1 and negatively regulated the abundances of downstream genes of the Wnt/β‐catenin pathway and stem cell markers. Furthermore, miR‐150‐5p expression was decreased and β‐catenin level was enhanced in CD133+ glioma stem cells. Knockdown of miR‐150‐5p contributed to CD133? cells with stem cell‐like phenotype, whereas overexpression of miR‐150‐5p suppressed CD133+ glioma stem cell‐like characteristics. In conclusion, miR‐150‐5p inhibited the progression of glioma by controlling stem cell‐like characteristics via regulating the Wnt/β‐catenin pathway, providing a novel target for glioma treatment.     

CiRS‐7 targeting miR‐7 modulates the progression of non‐small cell lung cancer in a manner dependent on NF‐κB signalling

The purpose of this study was to figure out the effect of ciRS‐7/miR‐7/NF‐κB axis on the development of non‐small cell lung cancer (NSCLC). In response, the expressions of ciRS‐7, miR‐7 and NF‐κB subunit (ie RELA) within NSCLC tissues and cell lines were determined with real‐time polymerase chain reaction (RT‐PCR) and Western blot. Moreover, the NSCLC cells were transfected with pcDNA3‐ciRS‐7‐ir, pcDNA3‐ciRS‐7, miR‐NC and miR‐7 mimic. Furthermore, the targeted relationships between ciRS‐7 and miR‐7, as well as between miR‐7 and RELA, were confirmed by luciferase reporter assay. The proliferation, migration and apoptosis of NSCLC cells were, successively, measured using CCK‐8 assay, wound‐healing assay and flow cytometry test. Consequently, ciRS‐7, miR‐7, histopathological grade, lymph node metastasis and histopathological stage could independently predict the prognosis of patients with NSCLC (all P < .05). Moreover, remarkably up‐regulated ciRS‐7 and RELA expressions, as along with down‐regulated miR‐7 expressions, were found within NSCLC tissues and cells in comparison with normal ones (P < .05). Besides, overexpressed ciRS‐7 and underexpressed miR‐7 were correlated with increased proliferation, migration and invasion, yet reduced apoptosis rate of NSCLC cells (P < .05). More than that, ciRS‐7 specifically targeted miR‐7 to reduce its expressions (P < .05). Ultimately, the NSCLC cells within miR‐7 + RELA group were observed with superior proliferative, migratory and invasive capabilities than those within miR‐7 group (P < .05), and RELA expression was also significantly modified by both ciRS‐7 and miR‐7 (P < .05). In conclusion, the ciRS‐7/miR‐7/NF‐kB axis could exert pronounced impacts on the proliferation, migration, invasion and apoptosis of NSCLC cells.     

Upregulation of miR‐874‐3p and miR‐874‐5p inhibits epithelial ovarian cancer malignancy via SIK2

Based on miR‐874 expression levels in the GSE47841 microarray, we hypothesized that the mature products of miR‐874, miR‐874‐3p, or miR‐874‐5p, would inhibit epithelial ovarian cancer (EOC) cell proliferation, metastasis, and chemoresistance. We first examined miR‐874‐3p and miR‐874‐5p expression levels in primary EOC tumor tissue samples and found that they were significantly decreased. 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) cell proliferation and transwell assays revealed that miR‐874‐3p and miR‐874‐5p significantly inhibit EOC cell proliferation, migration, and invasion. Then, using MTT and soft agar assays of paclitaxel‐treated Caov3 and SKOV3 cells transfected with miR‐874‐3p and miR‐874‐5p, we found that miR‐874‐3p and miR‐874‐5p enhance EOC cell chemosensitivity. We then confirmed that serine/threonine‐protein kinase 2 (SIK2) was a target gene of miR‐874‐3p and miR‐874‐5p. Overall, the results of this study indicate that SIK2 expression can serve as a prognostic biomarker for EOC and that miR‐874‐3p and miR‐874‐5p have the potential to enhance clinical treatment of EOC.     

Hsa_circ_0128846 promotes tumorigenesis of colorectal cancer by sponging hsa‐miR‐1184 and releasing AJUBA and inactivating Hippo/YAP signalling

Hsa_circ_0128846 was found to be the most significantly up‐regulated circRNA in our bioinformatics analysis. However, the role of hsa_circ_0128846 in colorectal cancer has not been explored. We thus aim to explore the influence and mechanism of hsa_circ_0128846 in colorectal cancer by sponging its downstream miRNA target miR‐1184. We collected 40 colorectal cancer patients’ tumour tissues to analyse the expression of hsa_circ_0128846, miR‐1184 and AJUBA using qRT‐PCR and Western blot where needed. Then, we constructed stably transfected SW480 and HCT116 cells to study the influence of hsa_circ_0128846, miR‐1184 and AJUBA on colorectal cancer cell phenotypes. To obtain reliable results, a plethora of experiments including RNA immunoprecipitation assay, flow cytometry, EdU incorporation assay, wound healing migration assay, transwell invasion assay and live imaging of nude mice xenograft assay were performed. The binding relationship between hsa_circ_0128846, miR‐1184 and AJUBA mRNA in colorectal cancer was validated by reported gene assay. In colorectal cancer tissues, circ_0128846 and AJUBA were both significantly up‐regulated, while miR‐1184 was significantly down‐regulated compared with healthy tissues. Meanwhile, hsa_circ_0128846 can absorb miR‐1184 to promote the progression of CRC in vivo and SW480 and HCT116 cell phenotypes in vitro. The knockdown of AJUBA, a downstream target of miR‐1184, reversed the effect of miR‐1184 in CRC cells via enhancing the phosphorylation of the Hippo/YAP signalling pathway proteins MST1, LATS1 and YAP. This study revealed that hsa_circ_0128846 contributed to the development of CRC by decreasing the expression of miR‐1184, thereby increasing AJUBA expression and inactivating Hippo/YAP signalling.