miR-340 inhibits tumor cell proliferation and induces apoptosis by targeting multiple negative regulators of p27 in non-small cell lung cancer

An miR-340-5p-macrophage feedback loop modulates the progression and tumor microenvironment of glioblastoma multiforme

MicroRNAs (miRNAs) have been shown to be involved in the progression and tumor microenvironment of glioblastoma multiforme (GBM). Our previous research has indicated that miR-340-5p has an antitumor effect in vitro. However, the role of miR-340-5p in GBM has not been fully elucidated. Here, we show that downregulation of miR-340-5p in GBM is correlated with tumor size, recurrence, and poor survival. Moreover, we found that miR-340-5p levels are correlated with the density of tumor-associated macrophages (TAMs) and M2-polarized TAMs in GBM. Biofunctional investigations revealed that downregulation of miR-340-5p promoted TAM recruitment and M2-TAMs polarization in vitro and in vivo. In addition, we found that upregulation of miR-340-5p inhibited tumor growth and was associated with good prognosis in vivo. Through gene expression profiles and bioinformatics analysis, we showed that miR-340-5p directly targets POSTN, which recruited TAMs through integrin αvβ3. Downregulation of miR-340-5p in GBM did not induce the differentiation of TAMs into polarized M2 cells but was able to promote the M2 polarization of TAMs through directly targeting LTBP-1. Furthermore, we found that M2-TAMs promoted tumorigenesis and were associated with a poor prognosis in vivo. In an in vitro study, we demonstrated that M2-TAMs inhibited miR-340-5p expression in GBM cells by upregulation of TGFβ-1, which increased HMGA-2 expression in GBM. A ChIP assay confirmed that HMGA-2 transcriptionally suppressed miR-340-5p expression. Patients with low-miR-340-5p expression, high CD163, high POSTN, high LIBP1 levels, and high HMGA-2 had a poor prognosis with shorter overall survival, confirming data from the TCGA database. These findings suggest that an miR-340-5p-macrophage feedback loop modulates the progression and tumor microenvironment of GBM and may represent a prognostic biomarker and therapeutic strategy for GBM.

High expression of long intergenic non-coding RNA LINC00662 contributes to malignant growth of acute myeloid leukemia cells by upregulating ROCK1 via sponging microRNA-340-5p

Long non-coding RNAs (lncRNAs) have emerged as crucial regulatory factors in diverse pathological processes, especially in tumorigenesis. Accumulating evidence has demonstrated that long intergenic non-coding RNA 00662 (LINC00662) is overexpressed in multiple cancers and facilitates cancer development and progression. However, whether LINC00662 is involved in acute myeloid leukemia (AML) remains unknown. This study was aimed to explore the expression, biological function and regulatory mechanism of LINC00662 in AML. Here, we found that LINC00662 was significantly increased in AML tissues and cell lines. Knockdown of LINC00662 significantly reduced the growth of AML cells and upregulated AML cell apoptosis. In contrast, overexpression of LINC00662 promoted AML cell growth. MicroRNA-340-5p (miR-340-5p) was predicted as a target of LINC00662. Luciferase reporter assays and RNA pull-down assays confirmed that LINC00662 directly interacted with miR-340-5p. Expression of miR-340-5p was downregulated in AML and silencing of LINC00662 upregulated miR-340-5p expression in AML cells. Moreover, overexpression of miR-340-5p inhibited cell growth and increased apoptosis in AML cells. Inhibition of miR-340-5p significantly reversed the inhibitory effect of LINC00662 silencing on AML cell growth. In addition, Rho-associated protein kinase 1 (ROCK1) was verified as a target gene of miR-340-5p in AML cells. Restoration of ROCK1 expression partially reversed LINC00662 silencing or miR-340-5p overexpression-mediated inhibitory effect on AML cell growth. Overall, our results demonstrate that LINC00662 contributes to the malignant growth of AML cells by upregulating ROCK1 via sponging miR-340-5p, highlighting the important role of the LINC00662/miR-340-5p/ROCK1 axis in regulating the malignant behavior of AML cells.

Effects of miR‑340 overexpression and knockdown on the proliferation and metastasis of NSCLC cell lines

The present study aimed to investigate the potential biological functions of microRNA-340 (miR-340) in non-small cell lung cancer (NSCLC) beyond its role as a critical regulator of tumorigenesis and tumor progression. The expression levels of miR-340 and RAB27B were analyzed by reverse transcription-quantitative polymerase chain reaction. Subsequently, the protein expression levels of RAB27A, RAB27B, RAB9A, RAB11A and BRAB21 were determined by western blot analysis. The expression levels of the aforementioned proteins in NSCLC tissues were analyzed by immunohistochemistry. RAB27B, as a potential target of miR-340 was investigated via a dual-luciferase reporter assay. The proliferative ability of PC9, A549 and BEAS-2B cells was detected with a Cell Counting kit-8 assay, while the migration and invasion of the NSCLC cells were analyzed using a Transwell assay. The results revealed that the expression levels of miR-340 in the NSCLC cells were significantly decreased compared with those in normal cells (BEAS-2B cells). RAB27B was proposed as a potential target gene of miR-340, and its expression was notably increased in the NSCLC cells. miR-340 overexpression inhibited the migration and invasion of the NSCLC cells by targeting RAB27B, while the knockdown of miR-340 exerted opposite effects. On the whole, these findings indicate that the miR-340/RAB27B axis may be actively involved in the occurrence of NSCLC. Thus, miR-340 and RAB27B may be novel therapeutic targets for the treatment of NSCLC.

MicroRNA-340-5p suppresses non-small cell lung cancer cell growth and metastasis by targeting ZNF503

Background

MicroRNAs (miRNAs) have been reported to play crucial roles in cancer cell processes, including proliferation, metastasis and cell cycle progression. We aimed to identify miRNAs that could act as suppressors of cell growth and invasion in non-small cell lung cancer (NSCLC).

Methods

Fifteen paired NSCLC tissue samples and pericarcinomatous normal tissues were collected and preserved in liquid nitrogen. The expression levels of miR-340-5p and ZNF503 mRNA were detected using a qPCR assay. The transfection of plasmids was conducted using Lipofectamine 3000 according to the manufacturer’s protocol. Cell proliferation was determined using a CCK-8 assay. The protein levels of endothelial–mesenchymal transition markers were measured using a western blot assay. Cell invasive ability was evaluated using a transwell assay. TargetScan was used to predict targets of miR-340. A dual luciferase reporter assay was performed to confirm a potential direct interaction between miR-340-5p and ZNF503.

Results

The expression level of miR-340-5p was frequently found to be lower in NSCLC tissues than in matched pericarcinomatous normal tissues. Overexpression of miR-340-5p significantly inhibited the proliferation and invasion NCI-H1650 (a NSCLC cell line), while inhibition of miR-340-5p stimulated cell growth. Using TargetScan, we predicted that ZNF503 could be a target of miR-340-5p. Further mechanistic studies demonstrated that the forced expression of ZNF503 could partially abrogate the miR-340-5p-mediated decrease in NCI-H1650 cell viability and invasion, suggesting that miR-340-5p suppressed cell growth and invasion in a ZNF503-dependent manner.

Conclusion

Our findings indicate that miR-340-5p inhibits NCI-H1650 cell proliferation and invasion by directly targeting ZNF503 and that miR-340-5p can serve as a potential therapeutic target for treating NSCLC.

Electronic supplementary material

The online version of this article (10.1186/s11658-019-0161-1) contains supplementary material, which is available to authorized users.

KLF5 regulated lncRNA RP1 promotes the growth and metastasis of breast cancer via repressing p27kip1 translation

Increasing evidence suggest that lncRNAs (long noncoding RNAs) play important roles in human cancer. Breast cancer is a heterogeneous disease and the potential involvement of lncRNAs in breast cancer remains unexplored. In this study, we characterized a novel lncRNA, RP1-5O6.5 (termed as RP1). We found that RP1 was highly expressed in breast cancer and predicted poor prognosis of breast cancer patients. Gain-of-function and loss-of-function assays showed that RP1 promoted the proliferation and metastasis of breast cancer cells in vitro and in vivo. Mechanistically, RP1 maintained the EMT and stemness states of breast cancer cells via repressing p27kip1 protein expression. RP1 combined with the complex p-4E-BP1/eIF4E to prevent eIF4E from interacting with eIF4G, therefore attenuating the translational efficiency of p27kip1 mRNA. Furthermore, we found that p27kip1 evidently downregulated Snail1 but not ZEB1 to inhibit invasion of breast cancer cells. Kruppel-like factor 5 (KLF5) was positively correlated with RP1 in breast cancer tissues. Moreover, we demonstrated that KLF5 recruited p300 to the RP1 promoter to enhance RP1 expression. Taken together, our findings demonstrated that KLF5-regulated RP1 plays an oncogenic role in breast cancer by suppressing p27kip1, providing support for the clinical investigation of therapeutic approaches focusing on RP1.

miR-340-FHL2 axis inhibits cell growth and metastasis in ovarian cancer

Although increasing evidence indicated that deregulation of microRNAs (miRNAs) contributed to tumor initiation and progression, but little is known about the biological role of miR-340 in ovarian cancer (OC). In this study, we found that miR-340 expression was downregulated in OC tissues compared with its expression in normal ovarian epithelium and endometrium, and treatment with 5-aza-2′-deoxycytidine (5-Aza-dC) or trichostatin A (TSA) increased miR-340 expression in OC cells. In addition, ectopic miR-340 expression inhibited OC cell growth and metastasis in vitro and in vivo. Four and a half LIM domains protein 2 (FHL2) was confirmed as a direct target of miR-340 and silencing FHL2 mimicked the effects of miR-340 in OC cells. Further mechanistic study showed that miR-340 inhibited the Wnt/β-catenin pathway by targeting FHL2, as well as downstream cell cycle and epithelial-to-mesenchymal transition (EMT) signals in OC cells. Moreover, the greatest association between miR-340 and FHL2 was found in 481 ovarian serous cystadenocarcinoma tissues via pan-cancer analysis. Finally, we revealed that lower miR-340 or higher FHL2 was associated with poor OC patient outcomes. Our findings indicate that the miR-340-FHL2 axis regulates Wnt/β-catenin signaling and is involved in tumorigenesis in OC. Therefore, manipulating the expression of miR-340 or its target genes is a potential strategy in OC therapy.

High serum CRP influences myocardial miRNA profiles in ischemia-reperfusion injury of rat heart

Objective

Prognosis of myocardial infarction tends to be worse when serum C-reactive protein (CRP) level is high. miRNAs are also known to be involved in different pathogeneses of heart diseases such as myocardial infarction. However, how CRP is involved in myocardial infarction has not been fully elucidated. We hypothesized that serum CRP changes the miRNA profile during ischemia-reperfusion injury (IRI) of the myocardium. To confirm this hypothesis, we performed global miRNA expression profiling of myocardium using IRI and CRP infusion rat model.

Methods

After ligation of the coronary artery of rat hearts, human serum CRP was intravenously injected, and reperfusion was performed (I/R+CRP group, n = 6). Control group consisted of the sham group (n = 3), IV CRP infusion group (CRP only, n = 3), and the I/R-only group (I/R only, n = 5). We evaluated 423 miRNA expression in non-ischemic areas and areas at risk (AAR) of each group using NanoString nCounter miRNA expression assay.

Results

MiR-124 was downregulated in non-ischemic myocardium in CRP-only group. In AAR, 7 miRNAs were commonly upregulated in both I/R-only and I/R+CRP groups. And additional 6 miRNAs were upregulated in the I/R+CRP group (miR-33, miR-409-3p, miR-384-3p, miR-3562, miR-101a, and miR-340-5p). Similarly, in the non-ischemic areas, 6 miRNAs were commonly upregulated in both I/R-only and I/R+CRP groups, and additional 5 miRNAs changed in the I/R+CRP group (upregulation of miR-3559-5p, miR-499, and miR-21 and downregulation of miR-500 and miR-532-3p).

Conclusion

We showed that when serum CRP level is high, IRI results in multiple miRNA profile changes not only in ischemic areas but also in non-ischemic myocardium. Our results may provide a strong basis for studying the role of CRP and miRNAs in ischemic heart disease.

Enhanced blebbing as a marker for metastatic prostate cancer

Highly metastatic prostate cancer cells flowing through a microfluidic channel form plasma membrane blebs: they form 27% more than normal cells and have a lower stiffness (about 50%). Hypo-osmotic stress assays (with ∼ 50 % osmolarity) show 22% more blebbing of highly metastatic than moderately metastatic and 30% more than normal cells. Plasma membrane blebbing is known to provide important metastatic capabilities to cancer cells by aiding cell detachment from the primary tumor site and increasing cell deformability to promote cell migration through the extracellular matrix. Increased blebbing was attributed by others to decreased phosphorylated ezrin, radixin, and moesin (ERM) (p-ERM) protein expression-p-ERMs bind the plasma membrane to the actin cortex and reduced p-ERM expression can weaken membrane-cortex attachment. Myosin II also influences blebbing as myosin's natural contraction generates tension in the actin cortex. This increases cellular hydrostatic pressure, causes cortex rupture, cytoplasm flow out of the cortex, and hence blebbing. Highly metastatic cells are surprisingly found to express similar ezrin and myosin II levels but higher moesin levels in comparison with lowly metastatic or normal cells-suggesting that their levels, contrary to the literature [G. Charras and E. Paluch, Nat. Rev. Mol. Cell Biol. 9(9), 730-736 (2008); J.-Y. Tinevez, U. Schulze, G. Salbreux, J. Roensch, J.-F. Joanny, and E. Paluch, Proc. Natl. Acad. Sci. U.S.A. 106(44), 18581-18586 (2009); M. Bergert, S. D. Chandradoss, R. A. Desai, and E. Paluch, Proc. Natl. Acad. Sci. U.S.A. 109(36), 14434-14439 (2012); E. K. Paluch and E. Raz: Curr. Opin. Cell Biol. 25(5), 582-590 (2013)], are not important in metastatic prostate cell blebbing. Our results show that reduced F-actin is primarily responsible for increased blebbing in these metastatic cells. Blebbing can thus serve as a simple prognostic marker for the highly incident and lethal metastatic prostate cancer.

MiR-216b suppresses cell proliferation, migration, invasion, and epithelial-mesenchymal transition by regulating FOXM1 expression in human non-small cell lung cancer

Background/aims: MiR-216b and forkhead box M1 (FOXM1) were demonstrated to exert their biological effects on the development and progression of tumors. This study aimed to investigate the expression and role of miR-216b and FOXM1 in tissues and cell lines of non-small cell lung cancer (NSCLC). Methods: The expressions of miR-216b and FOXM1 in NSCLC tissues and cells were detected by qRT-PCR and Western blot analysis. Cell proliferation was measured by CCK-8 assay. Cell migration and invasion were confirmed by Transwell assay. Finally, the bioinformatics and dual-luciferase reporter assay were conducted to validate the relationship of miR-216b and FOXM1. Results: Compared with normal tissues and cells, the expression of miR-216b was obviously decreased in NSCLC tissues and cells. However, the expressions of FOXM1 mRNA and protein were significantly increased, and negatively correlated with the expression of miR-216b. Multivariate Cox's regression analysis suggested that miR-216b or FOXM1 expression was an independent prognostic factor for patients with NSCLC. MiR-216b overexpression remarkably repressed cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of NSCLC cells. The bioinformatics and dual-luciferase reporter assay validated that the 3'-untranslated region (3'-UTR) of FOXM1 mRNA was indeed a direct target of FOXM1. In vitro, overexpression of FOXM1 partially eliminated inhibitory effects of miR-216b on cell proliferation, migration, and invasion, whereas inhibition of FOXM1 contributed to inhibitory effects mediated by miR-216b. Conclusion: MiR-216b inhibits cell proliferation, migration, invasion, and EMT by targeting the expression of FOXM1 in human NSCLC. These findings suggested a potential therapeutic role of miR-216b in patients of NSCLC.

Hepatitis B virus-regulated growth of liver cancer cells occurs through the microRNA-340-5p-activating transcription factor 7-heat shock protein A member 1B axis

Hepatocellular carcinoma (HCC) is a common cancer with poor prognosis. Hepatitis B virus (HBV) is one of the leading causes of HCC, but the precise mechanisms by which this infection promotes cancer development are not fully understood. Recently, miR‐340‐5p, a microRNA (miRNA) that has been identified as a cancer suppressor gene, was found to inhibit the migration and invasion of liver cancer cells. However, the effect of miR‐340‐5p on cell proliferation and apoptosis in HBV‐associated HCC remains unknown. In our study, we show that miR‐340‐5p plays an important role during HBV infection and hepatocellular carcinoma development. Specifically, this miRNA directly binds to the mRNA encoding activating transcription factor 7 (ATF7), a protein that both promotes cell proliferation and suppresses apoptosis through its interaction with heat shock protein A member 1B (HSPA1B). We further found that miR‐340‐5p is downregulated by HBV, which enhances ATF7 expression, leading to enhanced cell proliferation and inhibition of apoptosis. Notably, ATF7 is upregulated in HCC tissue, suggesting that HBV may target miR‐340‐5p in vivo to promote ATF7/HSPA1B‐mediated proliferation and apoptosis and regulate liver cancer progression. This work helps to elucidate the complex interactions between HBV and host miRNAs and further suggests that miR‐340‐5p may represent a promising candidate for the development of improved therapeutic strategies for HCC.

Circular RNA SNX29 Sponges miR-744 to Regulate Proliferation and Differentiation of Myoblasts by Activating the Wnt5a/Ca2+ Signaling Pathway

Myogenesis is a complex and precisely orchestrated process that is highly regulated by several non-coding RNAs and signal pathways. Circular RNAs (circRNAs) represent a novel subclass of endogenous non-coding RNAs that have been identified in multiple species and tissues and play a vital role in post-transcriptional regulation in eukaryotes, but the precise molecular mechanism of action remains largely unknown. Here, we screened a candidate circRNA derived from the SNX29 gene, termed circSNX29 from our previous circRNAs sequencing data of bovine skeletal muscle, and further characterized its regulation and function during muscle development. The overexpression of circSNX29 facilitated myoblasts differentiation and inhibited cell proliferation. Computational analysis using RNAhybrid showed the potential for circSNX29 to sponge to miR-744 with nine potential binding sites. We tested this via a luciferase screening assay and found that circSNX29 directly interacted with miR-744 and downregulation of miR-744 efficiently reversed the suppression of Wnt5a and CaMKIIδ. Importantly, through the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enrichment analysis, Fluo-4, AM, cell permeant-calcium ion fluorescent probing, and western blotting assays, we found that overexpression of Wnt5a and circSNX29 activated the non-canonical Wnt5a/Ca²⁺ pathway. Overall, the evidence generated by our study elucidates the regulatory mechanisms of circSNX29 to function as a sponge for miRNA-744 in bovine primary myoblasts.

RNA binding protein PUM2 promotes the stemness of breast cancer cells via competitively binding to neuropilin-1 (NRP-1) mRNA with miR-376a

Others and ours studies have established the promoting roles of NRP-1 (neuropilin-1) in breast cancer, however, the underlying mechanisms by which NRP-1 is regulated are still confused. Here, bioinformatics analysis indicated that RNA binding protein PUM2 could bind to NRP-1 mRNA. Clinical samples showed that PUM2 expression was significantly increased in breast cancer tissues, negatively correlated with the overall survival and relapse-free survival of breast cancer patients, and positively correlated with NRP-1 expression. Meanwhile, PUM2 expression was remarkably increased in non-adherent spheroids. in vitro experiments demonstrated that PUM2 knockdown attenuated the stemness of breast cancer cells, evident by the decrease of spheroid formation capacity, ALDH1 activity and stemness marker expression. Mechanistically, RNA immunoprecipitation (RIP) and luciferase reporter analysis indicated that PUM2 competitively bound to NRP 3'UTR with miR-376a, which had been previously confirmed by us to suppress the stemness of breast cancer cells, and increased NRP-1 mRNA stability and expression. Furthermore, ectopic expression of NRP-1 or miR-376a knockdown rescued the inhibitory effects of NRP-1 knockdown on the stemness of breast cancer cells. Thus, our results suggest that PUM2 could facilitate the stemness of breast cancer cells by competitively binding to NRP-1 3'UTR with miR-376a.

Mechanism of Low Expression of miR-30a-5p on Epithelial-Mesenchymal Transition and Metastasis in Ovarian Cancer

Metastasis of ovarian cancer is regulated by microRNAs. This study focused on the effects of miR-30a-5p on ovarian cancer migration and invasion. Our results showed that the miR-30a-5p and mucin type O-glycan biosynthesis are closely related to ovarian cancer, and that miR-30a-5p was downregulated in ovarian cancer cells. miR-30a-5p overexpression reduced cell viability and inhibited migration and invasion in HO-8910 and HO-8910PM cells. S phase kinase-associated protein 2 (SKP2), B cell lymphoma 9 (BCL9), and NOTHC1 are direct target genes of miR-30a-5p. MTDH, SKP2, BCL9, and NOTCH1 genes were overexpressed in ovarian cancer cells, and they are direct target genes of miR-30a-5p. miR-30a-5p overexpression inhibited epithelial-mesenchymal transition (EMT) process, while upregulation of SKP2, BCL9, and NOTCH1 gene expression levels reduced the inhibition of EMT process by miR-30a-5p. miR-30a-5p was lowly expressed in ovarian cancer, and such a phenomenon is related to ovarian cancer metastasis. miR-30a-5p might inhibit the migration and invasion of ovarian cancer cells by downregulating the expression of SKP2, BCL9, and NOTCH1 genes.

Involvement of the Dysregulation of miR-23b-3p, miR-195-5p, miR-656-5p, and miR-340-5p in Trastuzumab Resistance of HER2-Positive Breast Cancer Cells and System Biology Approach to Predict Their Targets Involved in Resistance

Resistance to trastuzumab has become a limiting factor for therapeutic efficacy of human epidermal growth factor 2 (HER2)-positive breast cancer. Different expression levels of miRNAs in cancer cells have been associated with poor prognosis and response to chemotherapy. The aim of this study was to evaluate miRNAs that were thought to be associated with HER2-positive breast cancer chemoresistance. In this study, the relative expression of candidate miRNAs to U6 RNA was evaluated in trastuzumab-resistant and trastuzumab-sensitive cells using relative real-time PCR. Our results demonstrated that miR-23b-3p, miR-195-5p, miR-656-5p, and miR-340-5p were significantly dysregulated. For the first time in this study, these miRNAs were identified to be involved in trastuzumab resistance. TargetScan and miRDB were then used for predicting the potential targets of the candidate miRNAs. Our results also revealed that the predicted potential targets of these miRNAs were strongly associated with drug resistance pathways. As a relative expression of candidate miRNAs was statistically different in trastuzumab-resistant and trastuzumab-sensitive cells, their potential targets were involved in drug resistance pathways. We strongly hypothesized the dysregulation of miRNAs as a possible mechanism of trastuzumab resistance. We also assumed that the strategic manipulation of these regulatory networks might be a possible therapeutic strategy to improve the results of chemotherapy for this resistance. However, more research is needed to evaluate the role of these miRNAs in the acquisition of trastuzumab resistance.

Long non-coding RNA SNHG14 exerts oncogenic functions in non-small cell lung cancer through acting as an miR-340 sponge

Long non-coding RNA (lncRNA) SNHG14 is previously found to be overexpressed in several types of cancers. However, the clinical significance and biological function of SNHG14 in non-small cell lung cancer (NSCLC) are still elusive. In the present study, we found that SNHG14 was aberrantly up-regulated in NSCLC tissues from patients and cell lines compared with their normal counterparts. Increased SNHG14 expression was closely associated with aggressive tumor progression and poor clinical outcome of NSCLC patients. Knockdown of SNHG14 inhibited NSCLC cell proliferation through inducing cell cycle arrest and apoptosis, whereas SNHG14 overexpression exerted the opposite effects. Animal experiment further revealed that down-regulated SNHG14 greatly inhibited NSCLC tumor growth in vivo Further studies demonstrated that SNHG14 might serve as a competing endogenous RNA (ceRNA) by sponging miR-340 in NSCLC cells. Taken together, our study demonstrated that SNHG14/miR-340 axis might play a novel role in regulating the malignant behaviors of NSCLC, which provided a new potential diagnostic and therapeutic strategy for this malignant disease.

miR-135 regulated breast cancer proliferation and epithelial-mesenchymal transition acts by the Wnt/β-catenin signaling pathway

Breast cancer (BC) is the most common cancer in women around the world. microRNAs (miRNAs/miRs) have been proved to be associated with the development and progression of breast cancer. In the present study, to elucidate the effects of dysregulated miR‑135 on cells and underlying mechanisms in BC, in vitro and in vivo experiments were conducted. The biological functions of miR‑135 were studied using MTT, colony formation, wound healing, transwell assays as well as tumorigenicity analysis. Gain‑ and loss‑ of function of miR‑135 studies revealed that ectopic expression of miR‑135 in MDA‑MB‑468 and MCF‑7 cells significantly inhibited cell growth, migration, invasion and EMT, at least in part through inhibiting the activation of the Wnt/β‑catenin pathway. Moreover, this was reversed in cells which were transfected with miR‑135 inhibitors. Taken together, the results of the present study provided evidence that miR‑135 acted as a tumor suppressor in BC, which may represent a novel therapeutic strategy for the diagnosis and prognosis of BC.

Therapeutic microRNAs in human cancer

MicroRNAs (miRNAs) are RNA molecules at about 22 nucleotide in length that are non-coding, which regulate gene expression in the post-transcriptional level by performing degradation or blocks translation of the target mRNA. It is known that they play roles in mechanisms such as metabolic regulation, embryogenesis, organogenesis, differentiation and growth control by providing post-transcriptional regulation of gene expression. With these properties, miRNAs play important roles in the regulation of biological processes such as proliferation, differentiation, apoptosis, drug resistance mechanisms in eukaryotic cells. In addition, there are miRNAs that can be used for cancer therapy. Tumor cells and tumor microenvironment have different miRNA expression profiles. Some miRNAs are known to play a role in the onset and progression of the tumor. miRNAs with oncogenic or tumor suppressive activity specific to different cancer types are still being investigated. This review summarizes the role of miRNAs in tumorigenesis, therapeutic strategies in human cancer and current studies.

LGR5 acts as a target of miR-340-5p in the suppression of cell progression and drug resistance in breast cancer via Wnt/β-catenin pathway

Breast cancer is one of the most common malignant tumors among females. Recent studies demonstrated that microRNAs (miRNAs) played an important role in the regulation of tumor progression. In our present study, we firstly detected miR-340-5p expression in breast cancer cell lines and found lower expression of miR-340-5p in breast cancer cell lines (MCF-7, MDA-MB-231, BT-549, ZR-75-1) through qRT-PCR. Overexpressed miR-340-5p inhibited cell proliferation and drug resistance to docetaxel with enhanced cell apoptosis of breast cancer cells. Through bioinformatic prediction, we found that LGR5 was a potential target of miR-340-5p. LGR5 was highly expressed in breast cancer cells. Relative expression of LGR5 was negatively regulated by miR-340-5p. Knockdown of LGR5 also inhibited cell proliferation and drug resistance to docetaxel with enhanced cell apoptosis of breast cancer cells. Moreover, knockdown of LGR5 decreased the expression of β-catenin, c-myc, Survivin. The activation of Wnt/β-catenin pathway contracted the effects of LGR5 siRNA, indicating that LGR5 siRNA inhibited cell proliferation and drug resistance with induced apoptosis via suppressing Wnt/β-catenin signaling pathway in breast cancer. Taken together, our study demonstrated that overexpressed miR-340-5p inhibited cell proliferation and drug resistance with increased apoptosis of breast cancer cells through down-regulating LGR5 expression via Wnt/β-catenin pathway. The miR-340-5p/LGR5 axis may provide a new perspective for treatment for breast cancer.

Aptamer-miR-34c Conjugate Affects Cell Proliferation of Non-Small-Cell Lung Cancer Cells

MicroRNAs (miRNAs) are key regulators of different human processes that represent a new promising class of cancer therapeutics or therapeutic targets. Indeed, in several tumor types, including non-small-cell lung carcinoma (NSCLC), the deregulated expression of specific miRNAs has been implicated in cell malignancy. As expression levels of the oncosuppressor miR-34c-3p are decreased in NSCLC compared to normal lung, we show that reintroduction of miR-34c-3p reduces NSCLC cell survival in vitro. Further, in order to deliver the miR-34c-based therapeutic selectively to tumor cells, we took advantage of a reported nucleic acid aptamer (GL21.T) that binds and inhibits the AXL transmembrane receptor and is rapidly internalized in the target cells. By applying methods successfully used in our laboratory, we conjugated miR-34c to the GL21.T aptamer as targeting moiety for the selective delivery to AXL-expressing NSCLC cells. We demonstrate that miR-34c-3p and the GL21.T/miR-34c chimera affect NSCLC cell proliferation and are able to overcome acquired RTK-inhibitor resistance by targeting AXL receptor. Thus, the GL21.T/miR-34c chimera exerts dual inhibition of AXL at functional and transcriptional levels and represents a novel therapeutic tool for the treatment of NSCLC.

Kaempferol suppresses proliferation but increases apoptosis and autophagy by up-regulating microRNA-340 in human lung cancer cells

BACKGROUND

Lung cancer is a leading cause of cancer-related deaths worldwide with unsatisfied prognosis. Kaempferol is a dietary flavonoid that inhibits tumorgenesis, and we aimed to uncover the underlying mechanism of kaempferol in lung cancer cells.

METHODS

A549 cells were stimulated with kaempferol, and then cell proliferation, apoptosis, autophagy and expression of miR-340 were assessed. Subsequently, effects of kaempferol on protein expression of phosphatase with tensin homology (PTEN) and key kinases in the phosphatidylinositol-3-kinase (PI3K)/AKT pathways were detected by Western blot analysis. Moreover, the effects of miR-340 inhibition on kaempferol-induced alterations in A549 cells were also studied.

RESULTS

Cell viability, proliferation and cyclinD1 expression level in A549 cells were all reduced by kaempferol. Conversely, cell apoptosis and autophagy were promoted by kaempferol. We found autophagy promoted apoptosis in kaempferol-treated A549 cells. Then, expression of miR-340 was identified to be up-regulated by kaempferol treatment. After treatments with kaempferol, PTEN level was elevated and levels of p-PI3K and p-AKT were decreased. Moreover, the alterations induced by kaempferol were abrogated by miR-340 inhibition.

CONCLUSION

Kaempferol inhibited proliferation but induced apoptosis and autophagy in A549 cells. Additionally, kaempferol might function through up-regulating miR-340, along with up-regulation of PTEN and inactivation of the PI3K/AKT pathway.

MicroRNA-340 inhibits squamous cell carcinoma cell proliferation, migration and invasion by downregulating RhoA

BACKGROUND

MicroRNAs are reported to play an important role in tumor growth and metastasis, including squamous cell carcinoma (SCC). Accumulative evidence has revealed that dysregulated miR-340 expression contributed to the carcinogenesis and development of various cancers.

OBJECTIVE

The aim of the current study was to investigate the role and the underlying mechanism of miR-340 in SCC cell proliferation, migration and invasion.

METHODS

Quantitative real-time PCR was performed to examine the expression of miR-340 in SCC tissues and cell lines. The function of miR-340 in SCC was investigated through Cell Counting Kit-8, wound healing, transwell migration and invasion assays. Bioinformatics analysis, luciferase reporter assay, western blotting and immunohistochemical analysis were conducted to predict and confirm the target gene of miR-340.

RESULTS

In the present study, we first found that miR-340 was significantly decreased in both SCC tissues and cell lines. Moreover, ectopic expression of miR-340 remarkably attenuated SCC cell proliferation, migration and invasion, whereas inhibition of endogenous miR-340 promoted SCC cell proliferation, migration and invasion in vitro. Our subsequent bioinformatics analysis and luciferase reporter assay showed that RhoA was a novel direct target of miR-340 in SCC cells, and the knockdown of RhoA expression rescued the effects of miR-340 inhibition on SCC cell proliferation, migration and invasion. More importantly, the expression of RhoA and miR-340 was negatively correlated in SCC tissues.

CONCLUSION

Our findings demonstrate the tumor suppressor role of miR-340 in SCC by directly regulating RhoA. Therefore, restoration of miR-340 expression can be a potential therapeutic approach for SCC treatment.

Downregulated microRNA-340-5p promotes proliferation and inhibits apoptosis of chondrocytes in osteoarthritis mice through inhibiting the extracellular signal-regulated kinase signaling pathway by negatively targeting the FMOD gene

PURPOSE

Osteoarthritis (OA) is a degenerative joint disease that leads to the destruction of joint function. The aim of this study is to investigate the effects of microRNA-340-5p (miR-340-5p) and its target gene, FMOD, on the proliferation and apoptosis of chondrocytes in mice with OA through the extracellular signal-regulated kinase (ERK) signaling pathway.

MATERIALS

Twenty healthy C57BL/6J mice aged 15 months with a weight of 50 ± 2 g were selected. Ten mice were treated using a unilateral knee anterior cruciate ligament transection as well as a medial meniscectomy to establish the OA model. Besides, another 10 mice were used as the control group.

METHODS

A reverse transcription quantitative polymerase chain reaction and Western blot analysis methods were used to examine the expressions of related genes in cells of each group. A 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide assay and flow cytometry were also conducted to evaluate the cell function after transfection had been completed.

RESULTS

The expressions of fibromodulin (FMOD), type II collagen (Col II), B-cell lymphoma-2 (Bcl-2), sex-determining region of Y chromosome (SRY)-related high-mobility group-box gene 9 (Sox9), and proliferating cell nuclear antigen (PCNA) were decreased, whereas the expressions of miR-340-5p, runt-related transcription factor-2 (Runx2), Bcl-2-associated X protein (Bax), and ERK1/2 were elevated in the OA mice. Downregulation of miR-340-5p and upregulation of FMOD decreased the expressions of Runx2, Bax, and ERK1/2, and cell apoptosis of chondrocytes, and increased the expressions of FMOD, Col II, Bcl-2, Sox9, and PCNA, and cell proliferation.

CONCLUSION

This study suggests that downregulation of miR-340-5p plays a role in promoting cell proliferation and suppressing cell apoptosis of chondrocytes in OA mice through inhibition of the ERK signaling pathway via the FMOD gene.

Lentinan up-regulates microRNA-340 to promote apoptosis and autophagy of human osteosarcoma cells

BACKGROUND

Osteosarcoma (OS) is a common tumor of bone, and the high incidence and poor prognosis of OS call for novel therapeutic strategies. We aimed to explore the functional role of lentinan (LNT) in human OS MG63 cells as well as the underlying mechanisms.

METHODS

Cell viability of MG63 cells under LNT stimulation was measured by CCK-8 assay to explore the adequate concentration of LNT. Cell proliferation, apoptosis and expression of microRNA (miR)-340 in MG63 cells after LNT treatments were assayed by BrdU incorporation assay, flow cytometry assay and quantitative reverse transcription PCR, respectively. Expression of proteins associated with cell cycle, apoptosis, and autophagy were determined by western blot analysis. Subsequently, whether LNT affected MG63 cells through miR-340 as well as the related signaling pathway was explored.

RESULTS

Cell viability was reduced by 5-100 mg/mL of LNT. Percentage of BrdU-positive cells was reduced while that of apoptotic cells was enhanced by LNT treatment. LNT decreased cyclin D1 level but increased levels of active caspase-3 and caspase-9. After treatment, LNT enhanced LC3B-II/LC3B-I and Beclin-1 levels but reduced the p62 level. The miR-340 level was up-regulated by LNT, and further experiments showed LNT promoted apoptosis and autophagy through up-regulating miR-340. Moreover, LNT reduced the phosphorylated levels of MAPK and ERK through up-regulating miR-340.

CONCLUSION

LNT reduced proliferation and induced apoptosis and autophagy by up-regulating miR-340 in MG63 cells, along with inhibition of the MAPK/ERK pathway.

Multiple functions of p27 in cell cycle, apoptosis, epigenetic modification and transcriptional regulation for the control of cell growth: A double-edged sword protein

The cell cycle is controlled by precise mechanisms to prevent malignancies such as cancer, and the cell needs these tight and advanced controls. Cyclin dependent kinase inhibitor p27 (also known as KIP₁) is a factor that inhibits the progression of the cell cycle by using specific molecular mechanisms. The inhibitory effect of p27 on the cell cycle is mediated by CDKs inhibition. Other important functions of p27 include cell proliferation, cell differentiation and apoptosis. Post- translational modification of p27 by phosphorylation and ubiquitination respectively regulates interaction between p27 and cyclin/CDK complex and degradation of p27. In this review, we focus on the multiple function of p27 in cell cycle regulation, apoptosis, epigenetic modifications and post- translational modification, and briefly discuss the mechanisms and factors that have important roles in p27 functions.

MiR-340 suppresses the metastasis by targeting EphA3 in cervical cancer

MicroRNAs (miRNAs) play key roles in cervical cancer metastasis progression. Accumulated evidences have revealed that miRNAs are related to the pathophysiological process. However, the role of miR-340 in cervical cancer and how it works is still not fully interpreted. Using qRT-PCR to examine the expression of miR-340 in cervical cancer tissues. Transwell migration and invasion experiments were used to detect the role of miR-340 in migration and invasion. Luciferase reporter assay, qRT-PCR, and Western blot were used to detect the relationship between miR-340 and EphA3. Using Transwell migration and invasion experiments to investigate the role of EphA3 on migration and invasion. Restoration expriments were also performed. Western blot was used to assay the influence of miR-340 and EphA3 on EMT. We found that miR-340 was downregulated in cervical cancer tissues compared with the normal tissues. Transwell migration and invasion experiments indicated that overexpression of miR-340 frequently inhibited the migration and invasion of cervical cancer cells. EphA3 is a target of miR-340, and ectopic expression of EphA3 can promote the migration and invasion of cervical cancer cells, whereas restoration of EphA3 in miR-340-overexpressing cervical cancer cells reversed the suppressive effects of miR-340. What's more, the process of migration and invasion which regulated by miR-340/EphA3 was depended on adjusting the EMT way. These findings indicate that miR-340 may act as an anti-tumor factor during the process of tumor metastasis through targeting EphA3, suggesting that miR-340 might be a potential new diagnostic and therapeutic molecule for the treatment of cervical cancer.

microRNA-340 influences cell proliferation, apoptosis and invasion by targeting NF-κB1 in gastric cancer

Gastric cancer is a serious threat to human health, and its pathogenesis may be regulated by a variety of mRNAs. Abnormal expression of microRNA-340 has been frequently reported in many malignant neoplasms, while the molecular mechanism of miR-340 has not been explored in gastric cancer. In this study, the mRNA level of miR-340 was determined by real-time PCR in GC cell lines. The miR-340 mimic was transiently transfected into GC cells by using Lipofectamine™ 2000 reagent. The BrdU-ELISA results showed that introduction of miR-340 inhibited cell proliferation. It was demonstrated that miR-340 mimic arrested cell cycle progression and promoted apoptosis of MKN-45 and BGC-823 cells. In addition, the overexpression of miR-340 could inhibit invasion and EMT of MKN-45 and BGC-823 cells. The expression of NF-κB1 was evidently reduced by up-regulation of miR-340. Luciferase reporter assay further confirmed that miR-340 could directly target the 3'UTR of NF-κB1. Moreover, overexpression of NF-κB1 transfected with miR-340 mimic partially reversed the inhibitory of miR-340 mimic in MKN-45 and BGC-823 cells. In conclusion, miR-340 induced cell apoptosis and inhibited invasion by down-regulation of NF-κB1, which might be a potential target in treatment and prevention of gastric cancer.

Lower miR-340 expression predicts poor prognosis of non-small cell lung cancer and promotes cell proliferation by targeting CDK4

Aberrantly microRNAs (miRs) expression is reported to be involved in tumorigenesis and development in non-small cell lung cancer (NSCLC). MiR-340 had been identified to be downregulated in NSCLC in the previous study. However, the underlying mechanisms of miR-340 involved in NSCLC progression still needed to be well known. In the present study, we confirmed that miR-340 expression was notably down-regulated in NSCLC tissues compared to matched adjacent noncancerous lung tissues by quantitative real time PCR (qRT-PCR) analyses. Lower miR-340 expression positively related to lymph node metastasis, larger tumor size, advanced TNM stage and poor prognosis of NSCLC patients. In vitro assays, we demonstrated that upregulation of miR-340 expression suppressed cell proliferation ability. Bioinformatics analysis and luciferase reporter assays revealed that miR-340 directly targeted the 3'-untranslated (3'UTR) region of CDK4 mRNA. Over-expression of miR-340 suppressed cell proliferation by regulating CDK4 expression in NSCLC cells. Additionally, we showed that increased miR-340 expression promoted the expression of cell proliferation related protein CDK6 expression, but decreasing the P15 and P21 expression. In vivo, we verified that miR-340 overexpression also inhibited tumor growth by regulating CDK4 expression. Therefore, these findings revealed miR-340 functions as a tumor suppressor in NSCLC cells and may provide a potential target of NSCLC treatment.

Nanos genes and their role in development and beyond

The hallmark of Nanos proteins is their typical (CCHC)2 zinc finger motif (zf-nanos). Animals have one to four nanos genes. For example, the fruit fly and demosponge have only one nanos gene, zebrafish and humans have three, and Fugu rubripes has four. Nanos genes are mainly known for their evolutionarily preserved role in germ cell survival and pluripotency. Nanos proteins have been reported to bind the C-terminal RNA-binding domain of Pumilio to form a post-transcriptional repressor complex. Several observations point to a link between the miRNA-mediated repression complex and the Nanos/Pumilio complex. Repression of the E2F3 oncogene product is, indeed, mediated by cooperation between the Nanos/Pumilio complex and miRNAs. Another important interaction partner of Nanos is the CCR4-NOT deadenylase complex. Besides the tissue-specific contribution of Nanos proteins to normal development, their ectopic expression has been observed in several cancer cell lines and various human cancers. An inverse correlation between the expression levels of human Nanos1 and Nanos3 and E-cadherin was observed in several cancer cell lines. Loss of E-cadherin, an important cell-cell adhesion protein, contributes to tumor invasion and metastasis. Overexpression of Nanos3 induces epithelial-mesenchymal transition in lung cancer cell lines partly by repressing E-cadherin. Other than some most interesting data from Nanos knockout mice, little is known about mammalian Nanos proteins, and further research is needed. In this review, we summarize the main roles of Nanos proteins and discuss the emerging concept of Nanos proteins as oncofetal antigens.

Antrodia cinnamomea extract inhibits the proliferation of tamoxifen-resistant breast cancer cells through apoptosis and skp2/microRNAs pathway

BACKGROUND

Breast cancer is the most common cancer in women and affects 1.38 million women worldwide per year. Antiestrogens such as tamoxifen, a selective estrogen receptor (ER) modulator, are widely used in clinics to treat ER-positive breast tumors. However, remissions of breast cancer are often followed by resistance to tamoxifen and disease relapse. Despite the increasing understanding of the resistance mechanisms, effective regimens for treating tamoxifen-resistant breast cancer are limited. Antrodia cinnamomea is a traditional medicinal mushroom native only to Taiwan. In this study, we aimed to examine in vitro effect of antrodia cinnamomea in the tamoxifen-resistant cancer.

METHODS

Antrodia cinnamomea was studied for its biological activity against proliferation of tamoxifen-resistant breast cancer by XTT assay. Next, the underlying mechanism was studied by flow cytometry, qPCR and Western's blotting assay.

RESULTS

Our results revealed that the ethanol extract of antrodia cinnamomea (AC) can inhibit the growth of breast cancer cells, including MCF-7 cell and tamoxifen-resistant MCF-7 cell lines. Combination treatment with AC and 10- 6 M tamoxifen have the better inhibitory effect on the proliferation of tamoxifen-resistant MCF-7 cells than only AC did. AC can induce apoptosis in these breast cancer cells. Moreover, it can suppress the mRNA expression of skp2 (S-phase kinase-associated protein 2) by increasing the expressions of miR-21-5p, miR-26-5p, and miR-30-5p in MCF-7 and tamoxifen-resistant MCF-7 cells.

CONCLUSIONS

These results suggest that the ethanol extract of antrodia cinnamomea could be a novel anticancer agent in the armamentarium of tamoxifen-resistant breast cancer management. Moreover, we hope to identify additional pure compounds that could serve as promising anti-breast cancer candidates for further clinical trials.

A meta-analytic review of the association between two common SNPs in miRNAs and lung cancer susceptibility

Background

MicroRNAs (miRNAs) are involved in many biological processes, including tumor suppression. Multiple studies have shown an association between the miRNA-196a2 rs11614913 and miRNA-146a rs2910164 polymorphisms and cancer risk. However, the implications of the reported data are debatable and inconclusive.

Materials and methods

Relevant articles were retrieved from the PubMed, EMBASE, China National Knowledge Infrastructure, and WanFang databases from January 1, 2007, to April 30, 2017. Studies were assessed based on designated inclusion and exclusion criteria, and data were manually extracted from relevant studies by two investigators. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to explore the association between two single-nucleotide polymorphisms (SNPs) in miRNAs and lung cancer susceptibility.

Results

Nine eligible articles were included, consisting of 3,101 cancer cases and 3,234 controls for miRNA-196a2 rs11614913, and 3,483 cases and 3,578 controls for miRNA-146a rs2910164. For studies evaluating miRNA-196a2 rs11614913, significant associations with lung cancer risk were discovered. Overall, the pooled analysis showed that miRNA-196a2 rs11614913 was associated with a decreased cancer risk (CC vs TT: OR = 1.25, 95% CI: 1.09–1.44; CT vs TT: OR = 1.26, 95% CI: 1.03–1.53). For miRNA-146a rs2910164, only the CC genotype was found to be associated with high lung cancer risk (OR = 1.30, 95% CI: 1.13–1.49). Subgroup analyses based on ethnicity, source of control group, and country indicated that there were strong associations between miRNA-146a rs2910164 and cancer risk.

Conclusion

The results indicated that lung cancer risk was significantly associated with miRNA-196a2 rs11614913 and miRNA-146a rs2910164. These two common SNPs in miRNAs may be potential biomarkers of lung cancer.

MicroRNA-340 inhibits the growth and invasion of angiosarcoma cells by targeting SIRT7

MicroRNAs (miRNAs) are emerging as critical regulators for the development and progression of various cancers, including angiosarcoma. Accumulating evidence suggests that miRNA-340 (miR-340) is an important cancer-associated miRNA. However, little is known about the role of miR-340 in angiosarcoma. In this study, we aimed to investigate the potential biological functions of miR-340 and its potential target gene in angiosarcoma. Our results showed that miR-340 expression was significantly decreased in angiosarcoma compared with normal controls. The overexpression of miR-340 inhibited the growth and invasion of angiosarcoma cells, while the inhibition of miR-340 showed the opposite effect. Bioinformatics analysis predicted that Sirtuin 7 (SIRT7) was a potential target gene of miR-340. The binding relationship between miR-340 and the SIRT7 3'-untranslated region was verified by dual-luciferase reporter assay. Moreover, our results showed that miR-340 negatively regulated SIRT7 expression in angiosarcoma cells and an inverse correlation between miR-340 and SIRT7 expression was shown in clinical angiosarcoma tissues. We found that silencing SIRT7 significantly inhibited the proliferation and invasion of angiosarcoma cells. Notably, the overexpression of SIRT7 promoted the proliferation and invasion of angiosarcoma cells and also partially reversed the antitumor effect of miR-340 on angiosarcoma cell proliferation and invasion. Taken together, our results demonstrate that miR-340 inhibits the growth and invasion of angiosarcoma cells by targeting SIRT7. Our study provides evidence that the miR-340/SIRT7 axis may play an important role in the molecular pathogenesis of angiosarcoma and suggests that miR-340 and SIRT7 may be used as potential and novel therapeutic targets for the treatment of angiosarcoma.

Emerging landscape of circular RNAs in lung cancer

Lung cancer, the leading cause of cancer deaths worldwide, is characterized with malignant cell growth. Advances in next-generation sequencing has helped us further understand RNA and identify novel circular RNAs (circRNAs) that may be useful in the early diagnosis and treatment of lung cancer. Similar to other noncoding RNAs, circRNAs present diverse biological functions in normal and disease states, including various types of cancers. This review focuses mainly on the poorly understood functions of circRNA in lung cancer. This paper also summarizes the recent advances in circRNA biogenesis, analyzes the role of circRNAs in cancers, and discusses the potential mechanisms of circRNAs in lung cancer.

circFGFR4 Promotes Differentiation of Myoblasts via Binding miR-107 to Relieve Its Inhibition of Wnt3a

Muscle development is regulated under a series of complicate processes, and non-coding RNAs, such as microRNAs (miRNAs) and circular RNAs (circRNAs), have been reported to play important roles in regulating myoblast proliferation and differentiation. We found that miR-107 expression was high in skeletal muscle of Qinchuan cattle. Overexpression of miR-107 inhibited bovine myoblasts differentiation and protected cells from apoptosis. Wnt3a was identified as a target of miR-107 by luciferase activity, real-time qPCR, and western blotting assays. Knockdown of Wnt3a inhibited bovine myoblasts differentiation and apoptosis, and this effect was similar to miR-107 overexpression. We also found circFGFR4 to promote myoblasts differentiation and to induce cell apoptosis. Via luciferase screening and RNA pull-down assays, circFGFR4 was observed to sponge miR-107. Overexpression of circFGFR4 increased the expression of Wnt3a, whereas this effect was abolished by miR-107. These results demonstrated that circFGFR4 binding miR-107 promotes cell differentiation via targeting Wnt3a in bovine primary myoblasts.

Effects of miR-340 on hepatocellular carcinoma by targeting the DcR3 gene

In hepatocellular carcinoma (HCC), miR-340 plays a vital role in the regulation of tumor occurrence and deterioration, while DcR3 gene is involved in cancer cell proliferation and apoptosis. This study analyzed miR-340 in the serum of patients with HCC and healthy controls. Then, miR-340, DcR3, TGF-β1 and Smad2 expression were measured in HCC tissues and adjacent parts. Relationship between miR-340 and DcR3 was verified. Effects of miR-340 on human HepG2 cell proliferation and apoptosis were explored. miR-340, DcR3, TGF-β1, Smad2 mRNA and protein expression were also determined after miR-340 transfection. Compared with the control, miR-340 was significantly lower in the serum of the HCC patients (p < 0.01). miR-340 was lower in HCC tissues than in adjacent; however, DcR3, TGF-β1 and Smad2 were higher (p < 0.01). Furthermore, luciferase activity was significantly lower in the cells co-transfected with miR-340 mimics and DcR3-3'UTR-WT (p < 0.01), indicating that DcR3 was a target gene of miR-340. Moreover, decreased expression in DcR3, TGF-β1 and Smad2 was detected after miR-340 overexpression (p < 0.01), thus promoting apoptosis and blocking the proliferation of human HepG2 cells (p < 0.05). Furthermore, overexpression of DcR3 could activate the TGF-β1/Smad2 signal transduction pathway and increase the phosphorylation of Smad2. In conclusion, miR-340 plays a suppressive role in HCC development by targeting DcR3 and silencing the TGF-β1/Smad2 signaling pathway.

miR-340 and ZEB1 negative feedback loop regulates TGF-β- mediated breast cancer progression

MicroRNAs act as key regulators in carcinogenesis and progression in various cancers. In present study, we explored the role of miR-340 in the breast cancer progression. Our results showed that overexpression of miR-340 inhibits breast cancer cell proliferation and invasion, whereas depletion of miR-340 promotes breast cancer progression. Molecularly, ZEB1 was identified as a target gene of miR-340 and miR-340 suppressed the expression of ZEB1 by directly binding to the 3′-UTR of ZEB1. Furthermore, ZEB1 transcriptionally suppresses miR-340 expression. The negative feedback loop regulated TGF-β-mediated breast cancer progression. In conclusion, our data suggested that miR-340 acted as a tumor suppressor in breast cancer progression.

DNMT1/miR-200a/GOLM1 signaling pathway regulates lung adenocarcinoma cells proliferation

OBJECTIVES

Lung adenocarcinoma (LAD) comprises about 80% of all diagnosed lung cancers. However, the underlying regulatory mechanism of LAD cell proliferation is largely unclear. The emergence of microRNAs and molecular-targeted therapies adds a new dimension in our efforts to combat this deadly disease.

METHOD

In this work, the A549 and H1650 human lung cancer cell lines were used in this study. The proliferation was evaluated by the MTT and BrdU assay. The expression level of related proteins was detected by western blot.

RESULT

We reported GOLM1 was highly expressed in LAD cells and associated with low survival ratio and higher grade malignancy. Knockdown of GOLM1 repressed the LAD cell proliferation. Overexpression of GOLM1 promoted the cell proliferation. Further we found that the level of microRNA-200a (miR-200a) expression was low in LAD cells. miR-200a repress GOLM1 expression by directly targeting its 3? UTR. Overexpression of miR-200a repressed the cell proliferation and blocked the increase of LAD cell proliferation caused by GOLM1 overexpression. Further, we found that miR-200 was downregulated by DNMT1.Overexpression of DNMT1 blocked the function of miR-200a on repressing proliferation. We then found that knockdown of DNMT1 repressed LAD cell proliferation, which could be rescued by GOLM1 overexpression.

CONCLUSION

This work revealed the critical function of GOLM1/miR-200a/DNMT1 signaling pathway on regulating LAD cell proliferation, and might lay the foundation for further clinical treatment of LAD.

miFAST: A novel and rapid microRNA target capture method

MicroRNAs (miRNAs), small 22-25 nucleotide non-coding RNAs, play important roles in cellular and tumor biology. However, characterizing miRNA function remains challenging due to an abundance of predicted targets and an experimental bottleneck in identifying biologically relevant direct targets. Here, we developed a novel technique (miFAST) to identify direct miRNA target genes. Using miFAST, we confirmed several previously reported miR-340 target genes and identified five additional novel direct miR-340 targets in melanoma cells. This methodology can also be efficiently applied for the global characterization of miRNA targets. Utilizing miFAST to characterize direct miRNA targetomes will further our understanding of miRNA biology and function.

SRGAP1, a crucial target of miR-340 and miR-124, functions as a potential oncogene in gastric tumorigenesis

Slit-Robo GTPase-activating protein 1 (SRGAP1) functions as a GAP for Rho-family GTPases and downstream of Slit-Robo signaling. We aim to investigate the biological function of SRGAP1 and reveal its regulation by deregulated microRNAs (miRNAs) in gastric cancer (GC). mRNA and protein expression of SRGAP1 were examined by quantitative reverse transcription PCR (qRT-PCR) and western blot. The biological role of SRGAP1 was demonstrated through siRNA-mediated knockdown experiments. The regulation of SRGAP1 by miR-340 and miR-124 was confirmed by western blot, dual luciferase activity assays and rescue experiments. SRGAP1 is overexpressed in 9 out of 12 (75.0%) GC cell lines. In primary GC samples from TCGA cohort, SRGAP1 shows gene amplification in 5/258 (1.9%) of cases and its mRNA expression demonstrates a positive correlation with copy number gain. Knockdown of SRGAP1 in GC cells suppressed cell proliferation, reduced colony formation, and significantly inhibited cell invasion and migration. Luciferase reporter assays revealed that SRGAP1 knockdown significantly inhibited Wnt/β-catenin pathway. In addition, SRGAP1 was found to be a direct target of two tumor-suppressive miRNAs, miR-340 and miR-124. Concordantly, these two miRNAs were downregulated in primary gastric tumors and these decreasing levels w5ere associated with poor outcomes. Expression of miR-340 and SRGAP1 displayed a reverse relationship in primary samples and re-expressed SRGAP1, rescued the anti-cancer effects of miR-340. Taken together, these data strongly suggest that, apart from gene amplification and mutation, the activation of SRGAP1 in GC is partly due to the downregulation of tumor-suppressive miRNAs, miR-340 and miR-124. Thus SRGAP1 is overexpressed in gastric carcinogenesis and plays an oncogenic role through activating Wnt/β-catenin pathway.

MicroRNA-122-3p inhibits tumor cell proliferation and induces apoptosis by targeting Forkhead box O in A549 cells

The imbalance between cell proliferation and apoptosis was implicated to serve key roles in cancer pathogenesis. The characteristics of microRNAs (miRNAs/miRs) have attracted much attention in research focusing on cancer pathogenesis in recent years. miR-122-3p has been reported to be associated with a number of disease processes and pathogenesis, including lung cancer. The present study aimed to investigate the association of miR-122-3p expression level with cell proliferation and apoptosis in a lung cancer cell line. A549 cells were transfected with miR-122-3p to interrupt the expression of miR-122-3p. Subsequently, MTT and BrdU assay, and western blot were used to analyze the influence of miR-122-3p on lung cancer cell proliferation, cell viability and its underlying mechanism. The present study revealed that, by targeting p27, overexpression of miR-122-3p inhibited cell proliferation in lung cancer. Furthermore, the cell apoptosis analysis suggested that overexpression of miR-122-3p was able to inhibit cell apoptosis by targeting Forkhead box O. These findings suggest that miR-122-3p may be associated with the pathology and progression of lung cancer and be a new therapeutic target for this disease.

Prediction of potential drivers connecting different dysfunctional levels in lung adenocarcinoma via a protein-protein interaction network

Lung cancer is a serious disease that threatens an affected individual's life. Its pathogenesis has not yet to be fully described, thereby impeding the development of effective treatments and preventive measures. "Cancer driver" theory considers that tumor initiation can be associated with a number of specific mutations in genes called cancer driver genes. Four omics levels, namely, (1) methylation, (2) microRNA, (3) mutation, and (4) mRNA levels, are utilized to cluster cancer driver genes. In this study, the known dysfunctional genes of these four levels were used to identify novel driver genes of lung adenocarcinoma, a subtype of lung cancer. These genes could contribute to the initiation and progression of lung adenocarcinoma in at least two levels. First, random walk with restart algorithm was performed on a protein-protein interaction (PPI) network constructed with PPI information in STRING by using known dysfunctional genes as seed nodes for each level, thereby yielding four groups of possible genes. Second, these genes were further evaluated in a test strategy to exclude false positives and select the most important ones. Finally, after conducting an intersection operation in any two groups of genes, we obtained several inferred driver genes that contributed to the initiation of lung adenocarcinoma in at least two omics levels. Several genes from these groups could be confirmed according to recently published studies. The inferred genes reported in this study were also different from those described in a previous study, suggesting that they can be used as essential supplementary data for investigations on the initiation of lung adenocarcinoma. This article is part of a Special Issue entitled: Accelerating Precision Medicine through Genetic and Genomic Big Data Analysis edited by Yudong Cai & Tao Huang.

Long non-coding RNA n326322 promotes the proliferation and invasion in nasopharyngeal carcinoma

Long non-coding RNAs (lncRNAs) have been reported to perform significant roles in cancer development and progression. Our research has found that a novel lncRNA n326322 was higher in nasopharyngeal carcinoma (NPC) cells. Moreover, the gain and loss of functional approaches revealed that the overexpression of lncRNA-n326322 promoted NPC cell proliferation and invasion, whereas the downregulation of lncRNA-n326322 suppressed cell proliferation and invasion. Further experiments demonstrated that potential mechanism may be associated with the activation of PI3K/AKT and ERK/MAPK pathways. Taken together, these results indicate that lncRNA-n326322 is associated with tumorigenesis of NPC.

miR-340 predicts glioblastoma survival and modulates key cancer hallmarks through down-regulation of NRAS

Glioblastoma is the most common primary brain tumor in adults; with a survival rate of 12 months from diagnosis. However, a small subgroup of patients, termed long-term survivors (LTS), has a survival rate longer then 12–14 months. There is thus increasing interest in the identification of molecular signatures predicting glioblastoma prognosis and in how to improve the therapeutic approach. Here, we report miR-340 as prognostic tumor-suppressor microRNA for glioblastoma. We analyzed microRNA expression in > 500 glioblastoma patients and found that although miR-340 is strongly down-regulated in glioblastoma overall, it is up-regulated in LTS patients compared to short-term survivors (STS). Indeed, miR-340 expression predicted better prognosis in glioblastoma patients. Coherently, overexpression of miR-340 in glioblastoma cells was found to produce a tumor-suppressive activity. We identified NRAS mRNA as a critical, direct target of miR-340: in fact, miR-340 negatively influenced multiple aspects of glioblastoma tumorigenesis by down-regulating NRAS and downstream AKT and ERK pathways. Thus, we demonstrate that expression of miR-340 in glioblastoma is responsible for a strong tumor-suppressive effect in LTS patients by down-regulating NRAS. miR-340 may thus represent a novel marker for glioblastoma diagnosis and prognosis, and may be developed into a tool to improve treatment of glioblastoma.