Correlation of microRNA-375 downregulation with unfavorable clinical outcome of patients with glioma

Serum bta-miRNA-375 as a potential biomarker for the early diagnosis of enzootic bovine leukosis

To identify a biomarker for the early diagnosis of enzootic bovine leukosis (EBL) caused by bovine leukemia virus (BLV), we investigated the expression of a microRNA, bta-miR-375, in cattle serum. Using quantitative reverse-transcriptase PCR analysis, we measured bta-miR-375 levels in 27 samples from cattle with EBL (EBL cattle), 45 samples from animals infected with BLV but showing no clinical signs (NS cattle), and 30 samples from cattle uninfected with BLV (BLV negative cattle). In this study, we also compared the kinetics of bta-miR-375 with those of the conventional biomarkers of proviral load (PVL), lactate dehydrogenase (LDH), and thymidine kinase (TK) from the no-clinical-sign phase until EBL onset in three BLV-infected Japanese black (JB) cattle. Bta-miR-375 expression was higher in NS cattle than in BLV negative cattle (P < 0.05) and greater in EBL cattle than in BLV negative and NS cattle (P < 0.0001 for both comparisons). Receiver operating characteristic curves demonstrated that bta-miR-375 levels distinguished EBL cattle from NS cattle with high sensitivity and specificity. In NS cattle, bta-miR-375 expression was increased as early as at 2 months before EBL onset-earlier than the expression of PVL, TK, or LDH isoenzymes 2 and 3. These results suggest that serum miR-375 is a promising biomarker for the early diagnosis of EBL.

Comparison of Oncogenes, Tumor Suppressors, and MicroRNAs Between Schizophrenia and Glioma: The Balance of Power

The risk of cancer in schizophrenia has been controversial. Confounders of the issue are cigarette smoking in schizophrenia, and antiproliferative effects of antipsychotic medications. The author has previously suggested comparison of a specific cancer like glioma to schizophrenia might help determine a more accurate relationship between cancer and schizophrenia. To accomplish this goal, the author performed three comparisons of data; the first a comparison of conventional tumor suppressors and oncogenes between schizophrenia and cancer including glioma. This comparison determined schizophrenia has both tumor-suppressive and tumor-promoting characteristics. A second, larger comparison between brain-expressed microRNAs in schizophrenia with their expression in glioma was then performed. This identified a core carcinogenic group of miRNAs in schizophrenia offset by a larger group of tumor-suppressive miRNAs. This proposed "balance of power" between oncogenes and tumor suppressors could cause neuroinflammation. This was assessed by a third comparison between schizophrenia, glioma and inflammation in asbestos-related lung cancer and mesothelioma (ALRCM). This revealed that schizophrenia shares more oncogenic similarity to ALRCM than glioma.

Exosome-Encapsulated miR-31, miR-192, and miR-375 Serve as Clinical Biomarkers of Gastric Cancer

In recent years, microRNAs (miRNAs) derived from exosomes have been attracting attention as novel clinical biomarkers in a variety of cancers. In this study, plasma samples from 60 gastric cancer (GC) patients and 63 healthy individuals were collected, and the exosomal microRNAs (ex-miRNAs) were isolated. We determined the specific ex-miRNAs through miRNA microarray and a database of differentially expressed miRNAs called dbDEMC. Then, the expression levels of exosomal miR-31, miR-192, and miR-375 were analyzed by quantitative polymerase chain reaction (qRT-PCR). Compared to the matched controls, exosomal miR-31, miR-375, and miR-192 were significantly upregulated in GC patients. Also, they were found to be associated with gender, with miR-192 being significantly upregulated in male GC patients. Kaplan-Meier analysis indicated that high expressions of exosomal miR-31, miR-375, and miR-192 were positively correlated with poor clinical outcomes of GC patients. Cox univariate and multivariate analysis found that ex-miR-375 expression and TNM stage were independent prognostic factors of overall survival (OS). Our findings revealed that exosomal miR-31, miR-192, and miR-375 might serve as noninvasive, sensitive, and specific biomarkers for the diagnosis and prognosis of GC patients.

miR-370 is better than miR-375 as a non-invasive diagnostic biomarker for pediatric acute myeloid leukemia patients

BACKGROUND: Acute myeloid leukemia (AML) is characterized by heterogeneity in phenotypic, genotypic, and clinical traits. miRNAs play an important role in pathogenesis and diagnosis of adult AML. Such information is not available about miRNA expression role in pediatric AML. OBJECTIVE: We aimed to investigate the expression of miR-370 and miR-375 as new diagnostic biomarkers to discriminate pediatric AML patients and to predict their roles in the disease molecular basis. METHODS: The expression of both miR-370 and miR-375 in peripheral blood (PB) of pediatric AML patients was assessed by QPCR; their impact for diagnosis was evaluated by ROC curve and their roles in pediatric AML development were predicted by bioinformatics analysis. RESULTS: The expression of miR-370 and miR-375 levels were significantly decreased in pediatric AML patients, suggesting them as tumor suppressor miRNAs as supported by bioinformatics analysis. MiR-370 showed better potential and sensitivity toscreen pediatric AML patients and more significant correlation with AML risk than miR-375. This is the first study to report the positive correlation between both miR-370 and miR-375. CONCLUSION: miR-370 level in peripheral blood can serve as a potential non-invasive diagnostic biomarker and was significantly correlated with AML risk. We strongly recommend PB miRNAs as diagnostic biomarkers for pediatric AML.

Circ-CREBBP promotes cell tumorigenesis and glutamine catabolism in glioma by regulating miR-375/glutaminase axis

Circular RNA CREB-binding protein (circ-CREBBP) has been reported to involve in the tumorigenesis of glioma. However, the role and underlying molecular mechanism of circ-CREBBP in glioma glutamine catabolism remain unclear. The expression of circ-CREBBP, microRNA (miR)-375 and glutaminase (GLS) was detected using quantitative real-time polymerase chain reaction and western blot. The 3‑(4, 5‑dimethylthiazol‑2‑y1)‑2, 5‑diphenyl tetrazolium bromide (MTT), colony formation, flow cytometry and transwell assays were used to determine the effects of them on glioma cell malignant biological behaviors in vitro. Glutamine metabolism was analyzed using assay kits. Murine xenograft model was established to investigate the role of circ-CREBBP in vivo. The binding interactions between miR-375 and circ-CREBBP or GLS were confirmed by the dual-luciferase reporter assay. Circ-CREBBP was highly expressed in glioma tissues and cells, and high expression of circ-CREBBP predicted poor prognosis. Circ-CREBBP knockdown suppressed cell proliferation, migration, invasion and glutamine metabolism while expedited cell apoptosis in glioma in vitro, as well as impeded tumor growth in vivo. Circ-CREBBP directly targeted miR-375, which was demonstrated to restrain glioma cell growth, motility and glutamine metabolism. Moreover, miR-375 inhibition reverted the anticancer effects of circ-CREBBP knockdown on glioma cells. GLS was a target of miR-375, GLS silencing or the treatment of GLS inhibitor bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide (BPTES) impaired glioma cell malignant phenotypes and glutamine metabolism. Importantly, GLS up-regulation weakened the tumor-suppressive functions of miR-375 on glioma cells. Mechanistically, circ-CREBBP indirectly regulated GLS expression through sponging miR-375. In all, circ-CREBBP expedited glioma tumorigenesis and glutamine metabolism through miR-375/GLS axis, suggesting a promising target for combined glioma therapy.

MicroRNA-375: potential cancer suppressor and therapeutic drug

MiR-375 is a conserved noncoding RNA that is known to be involved in tumor cell proliferation, migration, and drug resistance. Previous studies have shown that miR-375 affects the epithelial-mesenchymal transition (EMT) of human tumor cells via some key transcription factors, such as Yes-associated protein 1 (YAP1), Specificity protein 1 (SP1) and signaling pathways (Wnt signaling pathway, nuclear factor κB (NF-κB) pathway and transforming growth factor β (TGF-β) signaling pathway) and is vital for the development of cancer. Additionally, recent studies have identified microRNA (miRNA) delivery system carriers for improved in vivo transportation of miR-375 to specific sites. Here, we discussed the role of miR-375 in different types of cancers, as well as molecular mechanisms, and analyzed the potential of miR-375 as a molecular biomarker and therapeutic target to improve the efficiency of clinical diagnosis of cancer.

Exosomal miR-375-3p breaks vascular barrier and promotes small cell lung cancer metastasis by targeting claudin-1

Background

High incidence of metastasis is the main cause of death for small cell lung cancer (SCLC), with its underlying molecular mechanisms remain unclear. Exosomal miRNAs are important regulators in metastatic processes of various tumors, but their specific role in SCLC metastasis is unknown.

Methods

Small RNA sequencing followed by qRT-PCR verification was used to screen the potential exosomal miRNAs that might mediate SCLC metastasis. SCLC-cell-secreted exosomes were labeled followed by incubating with vascular endothelial cells to evaluate exosome-mediated communication between SCLC cells and vascular endothelial cells. In vitro permeability assay and transendothelial migration assay were applied to investigate the function of exosomal miRNA on vascular endothelial cells. In vivo permeability assay and mouse lung colonization assay were used to verify the effects of exosomal miRNA on vascular barriers and SCLC metastasis in vivo. Proteomics technology, dual-luciferase reporter system together with rescue assays were conducted to excavate the downstream pathways of miRNA.

Results

Compared with 57 healthy volunteers and 46 non-small cell lung cancer patients, we identified that the level of exosomal miR-375-3p in 126 SCLC patients was obviously higher and was positively correlated with patient TNM stages. In vitro functional experiments found that SCLC-cell-secreted exosomal miR-375-3p could increase the permeability of vascular endothelial cells and facilitate the transendothelial migration of SCLC cells. In vivo, miR-375-3p-enriched exosomes also destroyed the barrier structure of lung, liver and brain tissues of mice, leaded to an increased blood vessel permeability and finally promoted SCLC metastasis. Mechanistically, SCLC-cell-secreted exosomal miR-375-3p was transferred to vascular endothelial cells. The internalized miR-375-3p broke the tight junction of vascular endothelial cells by directedly binding to the 3’UTR of tight junction protein claudin-1 and negatively regulating its expression. Overexpressing claudin-1 in vascular endothelial cells could rescue the broken vascular barriers induced by miR-375-3p.

Conclusions

Our findings underline the crucial roles of exosomal miRNA-375-3p in regulating vascular endothelial barrier integrity and SCLC metastasis. miRNA-375-3p has a great potential to be a novel biomarker monitoring metastasis and guiding clinical therapeutics of SCLC patients.

The impact of microRNAs on myeloid-derived suppressor cells in cancer

Inflammation promotes cancer development. To a large extent, this can be attributed to the recruitment of myeloid-derived suppressor cells (MDSCs) to tumors. These cells are known for establishing an immunosuppressive tumor microenvironment by suppressing T cell activities. However, MDSCs also promote metastasis and angiogenesis. Critically, as small non-coding RNAs that regulate gene expression, microRNAs (miRNAs) control MDSC activities. In this review, we discuss how miRNA networks regulate key MDSC signaling pathways, how they shape MDSC development, differentiation and activation, and how this impacts tumor development. By targeting the expression of miRNAs in MDSCs, we can alter their main signaling pathways. In turn, this can compromise their ability to promote multiple hallmarks of cancer. Therefore, this may represent a new powerful strategy for cancer immunotherapy.

Selective exosome exclusion of miR-375 by glioma cells promotes glioma progression by activating the CTGF-EGFR pathway

Background

Exosomes are membrane-bound extracellular vesicles of 40–150 nm in size, that are produced by many cell types, and play an important role in the maintenance of cellular homeostasis. Exosome secretion allows for the selective removal of harmful substances from cells. However, it remains unclear whether this process also takes place in glioma cells.

Methods

Herein, the role of the tumour-suppressor miR-375 was explored in human glioma cells. Immunoblotting and qRT-PCR experiments demonstrated a functional link between miR-375 and its target, connectivetissuegrowthfactor (CTGF), which led to the identification of the underlying molecular pathways. The exosomes secreted by glioma cells were extracted by ultracentrifugation and examined by transmission electron microscopy. Exosomal expression of miR-375 was then analysed by qRT-PCR; while the exosome secretion inhibitor, GW4869, was used to examine the biological significance of miR-375 release. Moreover, the dynamics of miR-375 release by glioma cells was investigated using fluorescently labelled exosomes. Finally, exosomal miR-375 release was examined in an orthotopic xenograft model in nude mice.

Results

MiR-375 expression was downregulated in gliomas. MiR-375 suppressed glioma proliferation, migration, and invasion by inhibiting the CTGF-epidermalgrowthfactorreceptor (EGFR) signalling pathway. MiR-375-containing exosomes were also identified in human peripheral blood samples from glioma patients, and their level correlated with disease progression status. Exosomal miR-375 secretion impacted the CTGF-EGFR pathway activity. Once secreted, exosomal miR-375 was not taken back up by glioma cells.

Conclusions

Exosomal miR-375 secretion allowed for sustained activation of the CTGF-EGFR oncogenic pathway, promoting the proliferation and invasion of glioma cells. These findings enhance our understanding of exosome biology and may inspire development of new glioma therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-020-01810-9.

Effects of lncRNA TUSC7 on the malignant biological behavior of osteosarcoma cells via regulation of miR-375

The present study aimed at investigating how long-chain non-coding RNA (lncRNA) tumor suppressor candidate 7 (TUSC7) regulates the malignant biological behavior of osteosarcoma cells. Tumor tissues and adjacent tissues of 30 patients with osteosarcoma were collected, and the expression levels of lncRNA TUSC7 and miR-375 were detected by RT-qPCR. lncRNA TUSC7 mimic and miR-375 mimic transfection models were established in MG63 osteosarcoma cells, and Transwell assays were used to detect the migration ability of MG63 cells. An MTT assay was used to assess the proliferation ability of MG63 cells. lncRNA TUSC7 in osteosarcoma tissue was significantly lower than that of adjacent tissues, while miR-375 levels were significantly higher than that of adjacent tissues; the two levels have a negative correlation. lncRNA TUSC7 mimic inhibited MG63 proliferation and migration abilities. miR-375 mimic promoted MG63 proliferation and migration abilities. The lncRNA TUSC7 mimic and miR-375 mimic co-transfection system could partially rescue the inhibition of lncRNA TUSC7 mimic on MG63 cells. In conclusion, lncRNA TUSC7 inhibited the proliferation and migration of MG63 osteosarcoma cells by regulating miR-375.

microRNA-mRNA network model in patients with achalasia

BACKGROUND

Achalasia is a rare idiopathic disease with a complex etio-pathogenesis still unknown. This study aimed to identify microRNA (miRNA)-mRNA regulatory networks underlying achalasia.

METHODS

The investigation was performed in tissue specimens from 11 patients and five controls using the microarray technology followed by an integrated bioinformatics analysis.

KEY RESULTS

One hundred and six miRNAs were significantly up-regulated and 64 were down-regulated in achalasia patients. The expression of the most 10 differential expressed miRNAs (miR-122-5p, miR-133a-3p, miR-504-5p, miR-187-3p, miR-133b, miR-200c-3p, miR-375, miR-200b-5p, miR-200b-3p, and miR203a) was confirmed by droplet digital PCR in an independent cohort. The interactions between the significant miRNAs and their targets uncovered 14 miRNA-mRNA interacting pairs with experimentally predicted genes (ie, FN1, ROCK2, DPYSL2), and 35 pairs with not experimentally target genes (ie, SULF1, MRVI1, PRKG1); all genes were involved in immune cell trafficking, skeletal and muscular system development, nervous system development macro-processes.

CONCLUSION & INFERENCES

The mRNA-miRNA regulatory networks described in this study provide new insights in the genetic background of the disease, suggesting further investigations in novel pathogenic mechanisms.

Up-regulation of microRNA-375 ameliorates the damage of dopaminergic neurons, reduces oxidative stress and inflammation in Parkinson's disease by inhibiting SP1

Background: This study is conducted to investigate the protective role of elevated microRNA-375 (miR-375) in dopaminergic neurons in Parkinson’s disease through down-regulating transcription factor specificity protein 1 (SP1).

Results: The successfully modeled rats with Parkinson’s disease showed aggregated neurobehavioral change, increased neuroinflammatory response and oxidative stress, and lowered dopamine content. Parkinson’s disease rats treated with overexpressed miR-375 displayed improved neurobehavioral change, ameliorated neuroinflammatory response and oxidative stress, heightened dopamine content and abated neuronal apoptosis by down-regulating SP1. Up-regulation of SP1 reversed the protective effect of upregulated miR-375 on Parkinson’s disease.

Conclusion: Up-regulation of miR-375 ameliorated the damage of dopaminergic neurons, reduced oxidative stress and inflammation in Parkinson’s disease by inhibiting SP1.

Methods: Parkinson’s disease rat model was established by targeted injection of 6-hydroxydopamine to damage the substantia nigra striatum. The successfully modeled Parkinson’s disease rats were intracerebroventricularly injected with miR-375 mimics or pcDNA3.1-SP1. The functions of miR-375 and SP1 in neurobehavioral change, neuroinflammatory response, oxidative stress, dopamine content and expression of apoptosis-related proteins in the substantia nigra of Parkinson’s disease rats were evaluated. The target relation of miR-375 and SP1 was confirmed by bioinformatics analysis and dual luciferase reporter gene assay.

A Chemotherapy-Driven Increase in Mcl-1 Mediates the Effect of miR-375 on Cisplatin Resistance in Osteosarcoma Cells

Background

Osteosarcoma (OS) is one of the most difficult cancers to treat due to its resistance to chemotherapy. The essential role played by Mcl-1 in promoting chemoresistance has been observed in a variety of cancers, including OS, while the underlying mechanism remains unclear.

Methods

We investigated the expression of Mcl-1 in 42 paired OS specimens obtained before and after adjuvant chemotherapy, and its correlation with clinicopathological characteristics. Loss and gain of function studies were performed to analyze the effects of Mcl-1 modulations on the chemosensitivity, and the mechanism involved in the deregulation of Mcl-1 in OS cells.

Results

In OS specimens, the expression of Mcl-1 was significantly upregulated after chemotherapy, and high Mcl-1 expression was associated with poorer overall survival and an increased recurrence rate. Furthermore, we demonstrated that chemotherapy-driven increased Mcl-1 decreased chemosensitivity by promoting tumour proliferation and inhibiting DNA damage. Moreover, Mcl-1 was found to be a direct target of miR-375 in OS cells. The knockdown of Mcl-1 phenocopied miR-375 downregulation, and the overexpression of miR-375 rescued the effects of cisplatin-induced DNA damage mediated by Mcl-1.

Conclusion

Our data indicated that chemotherapy-driven increase in the expression of Mcl-1 plays a critical role in chemoresistance, and the intervention of the miR-375/Mcl-1 axis may offer a novel strategy to enhance chemosensitivity in OS treatment.

Reduced microRNA 375 in colorectal cancer upregulates metadherin-mediated signaling

BACKGROUND

The human microRNA 375 (MIR375) is significantly downregulated in human colorectal cancer (CRC) and we have previously shown that MIR375 is a CRC-associated miRNA. The metadherin (MTDH) is a candidate target gene of MIR375.

AIM

To investigate the interaction and function between MIR375 and MTDH in human CRC.

METHODS

A luciferase reporter system was used to confirm the effect of MIR375 on MTDH expression. The expression levels of MIR375 and the target genes were evaluated by quantitative RT-PCR (qRT-PCR), western blotting, or immunohistochemistry.

RESULTS

MTDH expression was found to be upregulated in human CRC tissues compared to that in healthy controls. We show that MIR375 regulates the expression of many genes involved in the MTDH-mediated signal transduction pathways [BRAF-MAPK and phosphatidylinositol-4,5-biphosphate-3-kinase catalytic subunit alpha (PIK3CA)-AKT] in CRC cells. Upregulated MTDH expression levels were found to inhibit NF-κB inhibitor alpha, which further upregulated NFKB1 and RELA expression in CRC cells.

CONCLUSION

Our findings suggest that suppressing MIR375 expression in CRC regulates cell proliferation and angiogenesis by increasing MTDH expression. Thus, MIR375 may be of therapeutic value in treating human CRC.

METTL14 Suppresses CRC Progression via Regulating N6-Methyladenosine-Dependent Primary miR-375 Processing

Epigenetic alterations contributed to human carcinogenesis immensely. N6-methyladenosine (m6A) is one of the most preventive and abundant modifications on RNA molecules present in eukaryotes. However, the biological function of m6A methylation in colorectal cancer (CRC) remains largely unclear. Here, we found that METTL14 was downregulated in CRC tissues and cell lines, and closely correlated with overall survival (OS). METTL14 knockdown significantly reduced m6A levels in total RNAs and promoted CRC cell growth and metastasis, whereas METTL14 overexpression markedly increased m6A levels in total RNA and inhibited CRC cell growth and metastasis. Furthermore, we demonstrated that miR-375 was a downstream target of METTL14. We also verified that METTL14 suppressed CRC cell growth via the miR-375/Yes-associated protein 1 (YAP1) pathway, as well as inhibited CRC cell migration and invasion through the miR-375/SP1 pathway. Taken together, our studies showed an important role for METTL14 in CRC progression and provided novel insight into m6A modification in CRC progression.

Dysregulation of miR-375/AEG-1 Axis by Human Papillomavirus 16/18-E6/E7 Promotes Cellular Proliferation, Migration, and Invasion in Cervical Cancer

Cervical Cancer (CC) is a highly aggressive tumor and is one of the leading causes of cancer-related deaths in women. miR-375 was shown to be significantly down-regulated in cervical cancer cells. However, the precise biological functions of miR-375 and the molecular mechanisms underlying its action in CC are largely unknown. miR-375 targets were predicted by bioinformatics target prediction tools and validated using luciferase reporter assay. Herein, we investigated the functional significance of miR-375 and its target gene in CC to identify potential new therapeutic targets. We found that miR-375 expression was significantly downregulated in CC, and astrocyte elevated gene-1 (AEG-1) was identified as a target of miR-375. Our results also showed that ectopic expression of miR-375 suppressed CC cell proliferation, migration, invasion and angiogenesis, and increased the 5-fluorouracil-induced apoptosis and cell cycle arrest in vitro. In contrast, inhibition of miR-375 expression significantly enhanced these functions. Furthermore, HPV - 16 E6/E7 and HPV - 18 E6/E7 significantly down-regulates miR-375 expression in CC. HPV 16/18-E6/E7/miR-375/AEG-1 axis plays an important role in the regulation of cell proliferation, migration, and invasion in CC. Therefore, targeting miR-375/AEG-1 mediated axis could serve as a potential therapeutic target for CC.

Apoptotic tumor cell-derived microRNA-375 uses CD36 to alter the tumor-associated macrophage phenotype

Tumor-immune cell interactions shape the immune cell phenotype, with microRNAs (miRs) being crucial components of this crosstalk. How they are transferred and how they affect their target landscape, especially in tumor-associated macrophages (TAMs), is largely unknown. Here we report that breast cancer cells have a high constitutive expression of miR-375, which is released as a non-exosome entity during apoptosis. Deep sequencing of the miRome pointed to enhanced accumulation of miR-375 in TAMs, facilitated by the uptake of tumor-derived miR-375 via CD36. In macrophages, miR-375 directly targets TNS3 and PXN to enhance macrophage migration and infiltration into tumor spheroids and in tumors of a xenograft mouse model. In tumor cells, miR-375 regulates CCL2 expression to increase recruitment of macrophages. Our study provides evidence for miR transfer from tumor cells to TAMs and identifies miR-375 as a crucial regulator of phagocyte infiltration and the subsequent development of a tumor-promoting microenvironment.

The mode of miRNA transfer between tumour-immune cells is usually via exosomes. Here, the authors show that an alternative mode of transfer whereby miR-375 from apoptotic tumour cells can be transferred to tumour-associated macrophages via CD36 receptor, which induces macrophage migration and infiltration to the tumours.

The microRNA-375 as a potentially promising biomarker to predict the prognosis of patients with head and neck or esophageal squamous cell carcinoma: a meta-analysis

BACKGROUND

The prognostic value of microRNA-375 (miR-375) expression in squamous cell carcinoma (SCC) had been reported in the previous studies; however, the results remain inconsistent. This study was performed to investigate the prognostic significance of miR-375 expression in SCC based on all eligible evidences.

METHODS

Relevant studies were identified by searching PubMed, Embace, Medline, Cochrane Library, and China Biology Medicine disk. Survival outcome including overall survival (OS) and other survival outcomes were used as the primary endpoint to evaluate the prognostic outcome of patients with SCC. All statistical analyses were performed in RevMan software version 5.3 and STATA software version 14.1. Furthermore, the quality of included studies was assessed by The Newcastle-Ottawa Scale.

RESULTS

In total, 13 studies, including 1340 patients, met the inclusion criteria for our meta-analysis. The pooled analysis results indicated that downregulation of miR-375 significantly predicted poor OS (HR 1.58, 95% CI 1.34-1.88, P < 0.001). Downregulated miR-375 was also correlated with the other survival outcomes. Subgroup analysis based on tumor type found that lower expression of miR-375 was significantly related with poor OS in patients with esophageal squamous cell carcinoma (ESCC) (HR 1.58, 95% CI 1.29-1.94, P < 0.001) and head and neck squamous cell carcinoma (HNSCC) (HR 1.59, 95% CI 1.16-2.18, P = 0.004).

CONCLUSIONS

This meta-analysis demonstrated that the downexpression of miR-375 was significantly correlated with poor OS in patients with SCCs and indicated the potential clinical use of miR-375 as a molecular biomarker, particularly in assessing prognosis for patients with ESCC and HNSCC.

The role of microRNAs involved in PI3-kinase signaling pathway in colorectal cancer

In recent decades, cancer has been one of the most important concerns of the human community, which affects human life from many different ways, such as breast, lung, colorectal, prostate, and other cancers. Colorectal cancer is one of the most commonly diagnosed cancers in the world that has recently been introduced as the third leading cause of cancer deaths in the world. microRNAs have a very crucial role in tumorgenesis and prevention of cancer, which plays a significant role with influencing various factors through different signaling pathways. Phosphoinositide 3 (PI3)-kinase/AKT is one of the most important signaling pathways involved in the control and growth of tumor in colorectal cancer, through important proteins of this pathway, such as PTEN and AKT, that they can perform specific influence on this process. Our effort in this study is to collect microRNAs that act as tumor suppressors and oncomirs in this cancer through PI3-kinase/AKT signaling pathway.

MiR-375 Regulation of LDHB Plays Distinct Roles in Polyomavirus-Positive and -Negative Merkel Cell Carcinoma

MicroRNA-375 (miR-375) is deregulated in multiple tumor types and regulates important targets involved in tumorigenesis and metastasis. This miRNA is highly expressed in Merkel cell carcinoma (MCC) compared to normal skin and other non-MCC skin cancers, and its expression is high in Merkel cell polyomavirus (MCPyV)-positive (MCPyV+) and low in MCPyV-negative (MCPyV-) MCC tumors. In this study, we characterized the function and target of miR-375 in MCPyV+ and MCPyV- MCC cell lines. Ectopic expression of miR-375 in MCPyV- MCC cells resulted in decreased cell proliferation and migration, as well as increased cell apoptosis and cell cycle arrest. However, in MCPyV+ MCC cells, inhibition of miR-375 expression reduced cell growth and induced apoptosis. Additionally, the expression of lactate dehydrogenase B (LDHB), a known target of miR-375, was inversely correlated with miR-375. Silencing of LDHB reduced cell growth in MCPyV- cell lines, while its silencing in MCPyV+ cell lines rescued the cell growth effect mediated by miR-375 inhibition. Together, our results suggest dual roles of miR-375 and LDHB in MCPyV and non-MCPyV-associated MCCs. We propose that LDHB could be a therapeutic target in MCC and different strategies should be applied in virus- and non-virus-associated MCCs.

The ASH1-miR-375-YWHAZ Signaling Axis Regulates Tumor Properties in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a worldwide malignance, and the underlying mechanisms of this disease are not fully elucidated. In this study, the existence and function of achaete-scute homolog-1 (ASH1)-miR-375-YWHAZ signaling axis in HCC were determined. Our experiments and the Cancer Genome Atlas (TCGA) sequencing data analyses showed that ASH1 and miR-375 were significantly downregulated, whereas YWHAZ was significantly upregulated in HCC. Furthermore, we found that ASH1 positively regulates miR-375, and miR-375 directly downregulates its target YWHAZ. Gain- and loss-of-function study demonstrated ASH1 and miR-375 function as tumor suppressors, whereas YWHAZ acts as an oncogene in HCC. Animal experiment indicated that YWHAZ small interfering RNAs (siRNAs) (si-YWHAZ) delivered by nanoliposomes could suppress the growth of hepatoma xenografts and was well tolerant by nude mice. Further studies revealed that YWHAZ was involved in several protein networks, such as cell autophagy, epithelial-mesenchymal transition (EMT), apoptosis, cell cycle, invasion, and migration. In addition, the patient group with ASH1-high-expression-miR-375-high-expression-YWHAZ-low-expression was correlated with a better clinical prognosis compared with the opposite expression group. In conclusion, we proved the existence of ASH1-miR-375-YWHAZ signaling axis and interpreted its important role in driving HCC tumor progression.

MicroRNA-target cross-talks: Key players in glioblastoma multiforme

The role of microRNAs in brain cancer is still naive. Some act as oncogene and others as tumor suppressors. Discovery of efficient biomarkers is mandatory to debate that aggressive disease. Bioinformatically selected microRNAs and their targets were investigated to evaluate their putative signature as diagnostic and prognostic biomarkers in primary glioblastoma multiforme. Expression of a panel of seven microRNAs (hsa-miR-34a, hsa-miR-16, hsa-miR-17, hsa-miR-21, hsa-miR-221, hsa-miR-326, and hsa-miR-375) and seven target genes ( E2F3, PI3KCA, TOM34, WNT5A, PDCD4, DFFA, and EGFR) in 43 glioblastoma multiforme specimens were profiled compared to non-cancer tissues via quantitative reverse transcription-polymerase chain reaction. Immunohistochemistry staining for three proteins (VEGFA, BAX, and BCL2) was performed. Gene enrichment analysis identified the biological regulatory functions of the gene panel in glioma pathway. MGMT ( O-6-methylguanine-DNA methyltransferase) promoter methylation was analyzed for molecular subtyping of tumor specimens. Our data demonstrated a significant upregulation of five microRNAs (hsa-miR-16, hsa-miR-17, hsa-miR-21, hsa-miR-221, and hsa-miR-375), three genes ( E2F3, PI3KCA, and Wnt5a), two proteins (VEGFA and BCL2), and downregulation of hsa-miR-34a and three other genes ( DFFA, PDCD4, and EGFR) in brain cancer tissues. Receiver operating characteristic analysis revealed that miR-34a (area under the curve = 0.927) and miR-17 (area under the curve = 0.900) had the highest diagnostic performance, followed by miR-221 (area under the curve = 0.845), miR-21 (area under the curve = 0.836), WNT5A (area under the curve = 0.809), PDCD4 (area under the curve = 0.809), and PI3KCA (area under the curve = 0.800). MGMT promoter methylation status was associated with high miR-221 levels. Moreover, patients with VEGFA overexpression and downregulation of TOM34 and BAX had poor overall survival. Nevertheless, miR-17, miR-221, and miR-326 downregulation were significantly associated with high recurrence rate. Multivariate analysis by hierarchical clustering classified patients into four distinct groups based on gene panel signature. In conclusion, the explored microRNA-target dysregulation could pave the road toward developing potential therapeutic strategies for glioblastoma multiforme. Future translational and functional studies are highly recommended to better understand the complex bio-molecular signature of this difficult-to-treat tumor.

Knockdown of Long Noncoding RNA LUCAT1 Inhibits Cell Viability and Invasion by Regulating miR-375 in Glioma

Recently, long noncoding RNAs (lncRNAs) have emerged as new gene regulators and prognostic markers in several cancers, including glioma. Here we focused on lncRNA LUCAT1 on the progression of glioma. qRT-PCR was used to determine the expression of LUCAT1 and miR-375 in glioma tissues and cells. MTT and Transwell invasion assays were performed to determine the function of LUCAT1 in glioma progression. The bioinformatics tool DIANA was used to predict the targets of LUCAT1. Pearson’s correlation analysis was performed to explore the correlation between LUCAT1 and miR-375. In the present study, we showed that LUCAT1 was substantially upregulated in glioma tissues and cells. LUCAT1 inhibition significantly suppressed the proliferation and invasion of glioma cells. Subsequently, DIANA showed that miR-375 was predicted to contain the complementary binding sites to LUCAT1. Luciferase reporter assay showed that miR-375 directly targeted LUCAT1. In addition, we found that miR-375 was downregulated in glioma tissues and negatively correlated with LUCAT1 expression in glioma tissues. Furthermore, the results showed that miR-375 could rescue the function of LUCAT1 in glioma progression. The lncRNA LUCAT1 was critical for the proliferation and invasion of glioma cells by regulating miR-375. Our findings indicated that LUCAT1 might offer a potential novel therapeutic target for the treatment of glioma.

MicroRNA Regulation of Glycolytic Metabolism in Glioblastoma

Glioblastoma (GBM) is the most aggressive and common malignant brain tumour in adults. A well-known hallmark of GMB and many other tumours is aerobic glycolysis. MicroRNAs (miRNAs) are a class of short nonprotein coding sequences that exert posttranscriptional controls on gene expression and represent critical regulators of aerobic glycolysis in GBM. In GBM, miRNAs regulate the expression of glycolytic genes directly and via the regulation of metabolism-associated tumour suppressors and oncogenic signalling pathways. This review aims to establish links between miRNAs expression levels, the expression of GBM glycolytic regulatory genes, and the malignant progression and prognosis of GBM. In this review, the involvement of 25 miRNAs in the regulation of glycolytic metabolism of GBM is discussed. Seven of these miRNAs have been shown to regulate glycolytic metabolism in other tumour types. Further eight miRNAs, which are differentially expressed in GBM, have also been reported to regulate glycolytic metabolism in other cancer types. Thus, these miRNAs could serve as potential glycolytic regulators in GBM but will require functional validation. As such, the characterisation of these molecular and metabolic signatures in GBM can facilitate a better understanding of the molecular pathogenesis of this disease.

MicroRNA 375 regulates proliferation and migration of colon cancer cells by suppressing the CTGF-EGFR signaling pathway

MicroRNA 375 (MIR375) is significantly down regulated in human colorectal cancer (CRC) tissues; we have previously identified MIR375 as a colon cancer associated microRNA (miRNA). We identified putative MIR375 target genes by comparing the mRNA microarray analysis data of MIR375-overexpressing cells with the candidate MIR375 target genes predicted by public bioinformatic tools. We investigated that the connective tissue growth factor (CTGF) is a direct target gene of MIR375. Expression of CTGF, a ligand of epidermal growth factor receptor (EGFR), was markedly enhanced in human CRC tissues in comparison with the corresponding normal colon tissues. We demonstrated that the expression levels of molecules in EGFR signaling pathways were regulated by MIR375 in colorectal cells. Using immunohistochemistry and the xenograft of MIR375-overexpressing colorectal cells in mice, we showed that MIR375 regulates cell growth and proliferation, angiogenesis, cell migration, cell cycle arrest, apoptosis, and necrosis in colon cells. Furthermore, results of MIR375 overexpression and cetuximab treatment indicated that the apoptosis and necrosis in colon cells were synergistically enhanced. Our results suggest that the down-regulation of MIR375 modulates EGFR signaling pathways in human colorectal cells and tissues by increasing CTGF expression; therefore, MIR375 may have a therapeutic value in relation to human CRC.

The expression profiling of serum miR-92a, miR-375, and miR-760 in colorectal cancer: An Egyptian study

Dysregulation in microRNA expression is a common feature in colorectal cancer. Due to the inconsistent results regarding serum miR-92a expression pattern and the insufficient studies on serum miR-375 and miR-760, we aimed in this study to investigate their expression profile and diagnostic and prognostic power in Egyptian colorectal cancer patients. The expression profile of miR-92a, miR-375, and miR-760 was determined in the sera of 64 colorectal cancer patients using quantitative real-time reverse transcription polymerase chain reaction in comparison to 27 healthy control subjects. The expression fold change of the studied microRNAs was correlated with patients' clinicopathological features. Receiver operating characteristic curve analysis was done to determine the role of these microRNAs in colorectal cancer diagnosis and follow-up according to the yielded area under the curve. The expression pattern of miR-92a was significantly upregulated (3.38 ± 2.52, p < 0.0001), while both of miR-375 and 760 were significantly downregulated (-1.250 ± 1.80, p< 0.0001; -1.710 ± 1.88, p < 0.0001, respectively) in colorectal cancer than the control. MiR-92a was positively correlated ( r = 0.671, p = 0.0001), while miR-375 and miR-760 were inversely correlated ( r = -0.414, p = 0.001; r = -0.644, p = 0.0001) with advanced colorectal cancer stages. Receiver operating characteristic curve analysis disclosed the highest diagnostic potential for miR-760 to discriminate colorectal cancer patients and early-stage colorectal cancer from the control (area under the curve = 0.922 and 0.875, respectively), while the highest prognostic potential for discrimination between colorectal cancer stages was for miR-92a. In conclusion, serum level of miR-92a, miR-375, and miR-760 may serve as biomarkers of colorectal cancer in Egyptian patients with high diagnostic power for miR-760 and high prognostic power for miR-92a.

Potential involvement of miR-375 in the premalignant progression of oral squamous cell carcinoma mediated via transcription factor KLF5

To elucidate the genetic effect involved in the premalignant progression of chronic inflammation to cancer, we performed microRNA and mRNA profiling in oral lichen planus (OLP), oral squamous cell carcinoma (OSCC), and normal tissue from the same patients. We demonstrate the involvement of a suppressive microRNA, miR-375, in the regulation of this premalignant progression via KLF5, a transcription factor that modulates the expression of genes contributing to proliferation and apoptosis. We found that miR-375 abundance decreased in tissues with progression from the normal state to OLP and subsequently to OSCC. Restoration of miR-375 by transduction of a synthetic mimic into OSCC cells repressed cellular proliferation and promoted apoptosis, with concomitant down-regulation of KLF5, and vice versa. The direct binding of miR-375 to the 3′-untranslated region of KLF5 was further confirmed. Additionally, Survivin (BIRC5), a target of KLF5, was also regulated by miR-375, explaining the susceptibility of miR-375-mimic transfected cells to apoptosis. Further analysis of clinical specimens suggested that expression of KLF5 and BIRC5 is up-regulated during the progression from inflammation to cancer. Our findings provide novel insights into the involvement of microRNAs in progression of inflammation to carcinoma and suggest a potential early-stage biomarker or therapy target for oral carcinoma.

The Expression of miR-375 Is Associated with Carcinogenesis in Three Subtypes of Lung Cancer

Many studies demonstrated unique microRNA profiles in lung cancer. Nonetheless, the role and related signal pathways of miR-375 in lung cancer are largely unknown. Our study investigated relationships between carcinogenesis and miR-375 in adenocarcinoma, squamous cell carcinoma and small cell lung carcinoma to identify new molecular targets for treatment. We evaluated 723 microRNAs in microdissected cancerous cells and adjacent normal cells from 126 snap-frozen lung specimens using microarrays. We validated the expression profiles of miR-375 and its 22 putative target mRNAs in an independent cohort of 78 snap-frozen lung cancer tissues using quantitative reverse-transcriptase PCR. Moreover, we performed dual luciferase reporter assay and Western blot on 6 targeted genes (FZD8, ITGA10, ITPKB, LRP5, PIAS1 andRUNX1) in small cell lung carcinoma cell line NCI-H82. We also detected the effect of miR-375 on cell proliferation in NCI-H82. We found that miR-375 expression was significantly up-regulated in adenocarcinoma and small cell lung carcinoma but down-regulated in squamous cell carcinoma. Among the 22 putative target genes, 11 showed significantly different expression levels in at least 2 of 3 pair-wise comparisons (adenocarcinoma vs. normal, squamous cell carcinoma vs. normal or small cell lung carcinoma vs. normal). Six targeted genes had strong negative correlation with the expression level of miR-375 in small cell lung carcinoma. Further investigation revealed that miR-375 directly targeted the 3’UTR of ITPKB mRNA and over-expression of miR-375 led to significantly decreased ITPKB protein level and promoted cell growth. Thus, our study demonstrates the differential expression profiles of miR-375 in 3 subtypes of lung carcinomas and finds thatmiR-375 directly targets ITPKB and promoted cell growth in SCLC cell line.

MicroRNA as potential biomarkers in Glioblastoma

Glioblastoma is the most aggressive and lethal tumour of the central nervous system and as such the identification of reliable prognostic and predictive biomarkers for patient survival and tumour recurrence is paramount. MicroRNA detection has rapidly emerged as potential biomarkers, in patients with glioblastoma. Over the last decade, analysis of miRNA in laboratory based studies have yielded several candidates as potential biomarkers however, the accepted use of these candidates in the clinic is yet to be validated. Here we will examine the use of miRNA signatures to improve glioblastoma stratification into subgroups and summarise recent advances made in miRNA examination as potential biomarkers for glioblastoma progression and recurrence.

Low-level expression of microRNA-375 predicts poor prognosis in hepatocellular carcinoma

MicroRNAs are predicted to play fundamental roles in the tumorigenesis of hepatocellular carcinoma (HCC). MiR-375 is frequently downregulated in HCC and acts as a tumor suppressor by targeting multiple oncogenes. The objective of this study was to evaluate miR-375 expression and its relevance to the prognosis of HCC. MiR-375 expression was measured in cancerous tissues using qRT-PCR and dichotomized based on a median cutoff. The association between miR-375 expression and clinicopathological parameters and prognosis was subsequently determined. Expression levels of miR-375 were detected in a cohort of 38 HCC patients who underwent curative surgery. No significant correlations were observed between miR-375 expression and clinicopathological parameters, such as gender, age, performance status, preoperative serum AFP level, histological grade, HBV-DNA copy number, ascites, cirrhosis, tumor size, number of tumor nodules, and macrovascular invasion. However, miR-375 expression differs across CLIP scores significantly (p < 0.05). A trend toward poorer disease-free survival (DFS) was observed in patients with lower miR-375 expression compared to those with higher miR-375 expression (p = 0.307). Multivariate analysis demonstrated that low miR-375 expression was an independent prognostic predictor for progression (p = 0.032, risk ratio 3.273). Subgroup analysis revealed that low expression of miR-375 was significantly associated with adverse DFS in patients with poorly differentiated histology, higher serum AFP level (≥400 ng/ml), and advanced tumor stage (CLIP score 1∼3) (p = 0.017, 0.009, and 0.024, respectively). Our study demonstrates that miR-375 expression is significantly correlated with DFS and may be a potential prognostic biomarker of disease progression in HCC.

MicroRNA-375 Suppresses Extracellular Matrix Degradation and Invadopodial Activity in Head and Neck Squamous Cell Carcinoma

CONTEXT

Head and neck squamous cell carcinoma (HNSCC) is a highly invasive cancer with an association with locoregional recurrence and lymph node metastasis. We have previously reported that low microRNA-375 (miR-375) expression levels correlate with poor patient survival, increased locoregional recurrence, and distant metastasis. Increasing miR-375 expression in HNSCC cell lines to levels found in normal cells results in suppressed invasive properties. HNSCC invasion is mediated in part by invadopodia-associated degradation of the extracellular matrix.

OBJECTIVE

To determine whether elevated miR-375 expression in HNSCC cell lines also affects invadopodia formation and activity.

DESIGN

For evaluation of the matrix degradation properties of the HNSCC lines, an invadopodial matrix degradation assay was used. The total protein levels of invadopodia-associated proteins were measured by Western blot analyses. Immunoprecipitation experiments were conducted to evaluate the tyrosine phosphorylation state of cortactin. Human protease arrays were used for the detection of the secreted proteases. Quantitative real time-polymerase chain reaction measurements were used to evaluate the messenger RNA (mRNA) expression of the commonly regulated proteases.

RESULTS

Increased miR-375 expression in HNSCC cells suppresses extracellular matrix degradation and reduces the number of mature invadopodia. Higher miR-375 expression does not reduce cellular levels of selected invadopodia-associated proteins, nor is tyrosine phosphorylation of cortactin altered. However, HNSCC cells with higher miR-375 expression had significant reductions in the mRNA expression levels and secreted levels of specific proteases.

CONCLUSIONS

MicroRNA-375 regulates invadopodia maturation and function potentially by suppressing the expression and secretion of proteases.

MicroRNA-375 functions as a tumor suppressor in osteosarcoma by targeting PIK3CA

Osteosarcoma has become one of the most common primary malignant bone tumors in childhood and adult. Numerous studies have demonstrated that aberrant microRNA (miRNA) expression is involved in human disease including cancer. To date, the potential miRNAs regulating osteosarcoma growth and progression are not fully identified yet. Herein, we showed that miR-375 was frequently downregulated in osteosarcoma tissue and cell lines compared to normal human colon tissues. Overexpression of miR-375 resulted in decreased expression of PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha) at both mRNA and protein levels. We found that miR-375 overexpression markedly suppressed cell proliferation in vitro. And inhibition of miR-375 promotes osteosarcoma growth. Mechanistic studies showed that PIK3CA was a potential target of miR-375 and it mediated reduction of PIK3CA resulted in suppression of PI3K/Akt pathway. Taken together, our results demonstrate that miR-375 functions as a growth-suppressive miRNA and plays an important role in inhibiting the tumorigenesis through targeting PIK3CA in osteosarcoma.

miR-375 inhibits cell growth and correlates with clinical outcomes in tongue squamous cell carcinoma

miR-375 has been implicated in various types of cancers. However, its role in tongue squamous cell carcinoma (TSCC) remains unclear. This study aimed to investigate the effects of miR-375 on cell growth and the prognosis of TSCC patients. Using quantitative reverse transcription-polymerase chain reaction, we evaluated miR-375 expression in TSCC samples and TSCC cell lines. The results showed that miR-375 expression was significantly reduced in the TSCC tissues and cell lines. A low level expression of miR-375 in TSCC patients was related to poor of prognosis. Moreover, the effects of miR-375 overexpression on cell proliferation, the cell cycle and the expression of Sp1 and cyclin D1 were examined in TSCC cells. We demonstrated that overexpression of miR-375 significantly inhibited the cell proliferation and cell cycle progression in TSCC cell lines. Overexpression of miR-375 inhibited Sp1 expression by targeting the 3' untranslated region of the Sp1 transcript. The knockdown of Sp1 expression resulted in the subsequent downregulation of cyclin D1. Taken together, our study suggests that miR-375 inhibits the cell growth, and its expression is correlated with clinical outcomes in TSCC.

Circulating miR-375 and miR-199a-3p as potential biomarkers for the diagnosis of hepatocellular carcinoma

Aiming to find novel non-invasive biomarkers with high accuracy for the detention of early-stage hepatocellular carcinoma (HCC), we examined the predictive power of two microRNAs (miR; miR-375 and miR-199a-3p) as potential biomarkers in early-stage HCC. A total of 234 serum samples (78 samples from HCC patients, 156 samples from healthy controls) were collected. We measured the levels of the two mature microRNAs (miRNAs) (miR-375 and miR-199a-3p) with probe-based stem-loop quantitative reverse-transcriptase PCR (RT-qPCR) in all subjects. In addition, the correlation between the expression levels of two miRs and clinicopathological factors was explored. Receiver operating characteristic curve (ROC) analyses revealed that the two serum miRs could be promising biomarkers for HCC, with relatively high area under the curve (AUC) values as follows: miR-375, 0. 637 with 95 % confidence interval (CI) of 0.560-0.741; miR-199a-3p, 0. 883 with 95 % CI of 0.827-0.938. Stratified analyses indicated that circulating miR-199a-3p showed better predictive value in patients with long-term drinking. Our data suggested that circulating miR-375 and miR-199a-3p could be a novel serum biomarker for HCC. Nevertheless, further validating and improving study with larger sample should be conducted to confirm our results.

MicroRNA expression signatures determine prognosis and survival in glioblastoma multiforme--a systematic overview

Despite advances in our knowledge about glioblastoma multiforme (GBM) pathology, clinical challenges still lie ahead with respect to treatment in GBM due to high prevalence, poor prognosis, and frequent tumor relapse. The implication of microRNAs (miRNAs) in GBM is a rapidly expanding field of research with the aim to develop more targeted molecular therapies. This review aims to present a comprehensive overview of all the available literature, evaluating miRNA signatures as a function of prognosis and survival in GBM. The results are presented with a focus on studies derived from clinical data in databases and independent tissue cohorts where smaller samples sizes were investigated. Here, miRNA associated to longer survival (protective) and miRNA with shorter survival (risk-associated) have been identified and their signatures based on different prognostic attributes are described. Finally, miRNAs associated with disease progression or survival in several studies are identified and functionally described. These miRNAs may be valuable for future determination of patient prognosis and could possibly serve as targets for miRNA-based therapies, which hold a great potential in the treatment of this severe malignant disease.

Prognostic significance of microRNA-375 downregulation in solid tumors: a meta-analysis

Objective. Recently, many studies have shown that microRNAs (miRNA) exhibit altered expression in various cancers and may play an important role as prognostic biomarker of cancers. We performed a meta-analysis to evaluate the impact of miR-375 expression in solid tumors on patients' overall survival (OS). Methods. Studies were identified by searching PubMed, Embace, and Cochrane Library (last search update was in May 2014) and were assessed by further quality evaluation. The pooled hazard ratios (HRs) with 95% confidence intervals (CIs) for total and stratified analyses were calculated to investigate the association between miR-375 expression and cancer patients OS. Results. Our analysis results indicated that downregulation of miR-375 predicted poor OS (HR = 1.91, 95% CI 1.48–2.45, P < 0.001). Subgroup analyses showed that lower expression of miR-375 was significantly related with poor OS in patients with esophageal carcinoma (HR = 2.24, 95% CI 1.69–2.96, P < 0.001) and non-small-cell lung cancer (NSCLC) (HR = 1.71, 95% CI 1.31–2.24, P < 0.001). Conclusions. The findings from this meta-analysis suggest that miR-375 expression is associated with OS of patients with malignant tumors and could be a useful clinical prognostic biomarker.

Identification of conserved and novel microRNAs in cerebral ischemia-reperfusion injury of rat using deep sequencing

MicroRNAs are a class of noncoding small RNAs that regulate gene expression by inhibiting target genes at post-transcriptional levels. MicroRNAs have been highlighted in many organs and tissues, including the brain. To identify special microRNAs involved in ischemia-reperfusion injury, we performed a comprehensive small RNA profiling in rat model and the control using Illumina high-throughput sequencing. A total of 9,444,562 and 10,290,391 clean reads were sequenced from two small RNA libraries constructed, respectively. Three hundred fifty-eight known microRNAs were identified, in which 78 microRNAs exhibited significantly differential expression between model and control. In addition, 62 and 68 novel miRNAs were found in model and control, respectively. Comparative analysis showed that 24 novel microRNAs were differentially expressed with greater than six-fold change. The GO annotation suggested that predicted targets of microRNAs were enriched into the category of metabolic process, cell part, cell-extracellular communications, and so on. KEGG pathway analysis suggested that these genes were involved in many important pathways, mainly including signaling transduction, MAPK signaling pathway, NF-κB signaling pathway, and neurotrophin signaling pathway. Our findings provided a deeper understanding to the regulatory mechanism of microRNAs underlying cerebral ischemia, therefore benefitting the improvement of the protection and treatment strategies of this disease.

Drug resistance mediated by AEG-1/MTDH/LYRIC

AEG-1/MTDH/LYRIC has been shown to promote cancer progression and development. Overexpression of AEG-1/MTDH/LYRIC correlates with angiogenesis, metastasis, and chemoresistance to various chemotherapy agents in cancer cells originating from a variety of tissues. In this chapter, we focus on the role of AEG-1/MTDH/LYRIC in drug resistance. Mechanistic studies have shown that AEG-1/MTDH/LYRIC is involved in classical oncogenic pathways including Ha-Ras, myc, NFκB, and PI3K/Akt. AEG-1/MTDH/LYRIC also promotes protective autophagy by activating AMP kinase and autophagy-related gene 5. Another reported mechanism by which AEG-1/MTDH/LYRIC regulates drug resistance is by increasing loading of multidrug resistance gene (MDR) 1 mRNA to the polysome, thereby facilitating MDR1 protein translation. More recently, a novel function for AEG-1/MTDH/LYRIC as an RNA-binding protein was elucidated, which has the potential to impact expression of drug sensitivity or resistance genes. Finally, AEG-1/MTDH/LYRIC acts in microRNA-directed gene silencing via an interaction with staphylococcal nuclease and tudor domain containing 1, a component of the RNA-induced silencing complex. Altered microRNA expression and activity induced by AEG-1/MTDH/LYRIC represent an additional way that AEG-1/MTDH/LYRIC may cause drug resistance in cancer. The multiple functions of AEG-1/MTDH/LYRIC in drug resistance highlight that it is a viable target as an anticancer agent for a wide variety of cancers.

Roles of miR-375 in digestive tumors

MicroRNAs (miRNAs) are a group of small non-coding RNAs that regulate gene expression post-transcriptionally. A large body of evidence has indicated that dysregulation of miRNAs is an important hallmark of cancer. MiRNAs modulate malignant phenotypes of cancer by repressing many critical oncogenes or tumor suppressors. MiR-375 was firstly identified in pancreatic beta-cells and it can regulate insulin secretion and pancreatic development. Further studies found that miR-375 is significantly downregulated in multiple types of tumors, especially digestive system tumors, such as hepatocellular carcinoma, gastric cancer, esophageal cancer, and pancreatic cancer. Overexpression of miR-375 represses target genes, such as AEG-1, JAK2, ATG7, IGF1R, PDK1, 14-3-3Z and YAP1, and thereby inhibits malignant properties of cancer. It is also found that miR-375 in tissues or circulation could be used as a biomarker for diagnosis or prognosis prediction in digestive system tumors. Since miR-375 play an important role in the initiation and progression of digestive system tumors, it can become a novel therapeutic target. Monitoring the levels of miR-375 may contribute to the early diagnosis and prognosis prediction.

MicroRNA-375 inhibits colorectal cancer growth by targeting PIK3CA

Colorectal cancer (CRC) is the second most common cause of death from cancer. MicroRNAs (miRNAs) represent a class of small non-coding RNAs that control gene expression by triggering RNA degradation or interfering with translation. Aberrant miRNA expression is involved in human disease including cancer. Herein, we showed that miR-375 was frequently down-regulated in human colorectal cancer cell lines and tissues when compared to normal human colon tissues. PIK3CA was identified as a potential miR-375 target by bioinformatics. Overexpression of miR-375 in SW480 and HCT15 cells reduced PIK3CA protein expression. Subsequently, using reporter constructs, we showed that the PIK3CA untranslated region (3'-UTR) carries the directly binding site of miR-375. Additionally, miR-375 suppressed CRC cell proliferation and colony formation and led to cell cycle arrest. Furthermore, miR-375 overexpression resulted in inhibition of phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. SiRNA-mediated silencing of PIK3CA blocked the inhibitory effect of miR-375 on CRC cell growth. Lastly, we found overexpressed miR-375 effectively repressed tumor growth in xenograft animal experiments. Taken together, we propose that overexpression of miR-375 may provide a selective growth inhibition for CRC cells by targeting PI3K/Akt signaling pathway.

The emerging role of miR-375 in cancer

MicroRNAs (miRNAs) are evolutionarily conserved, small noncoding RNAs that are believed to play fundamental roles in various biological processes through regulation of gene expression at the level of posttranscription. MiR-375 was first identified as a pancreatic islet-specific miRNA regulating insulin secretion. However, further study revealed that miR-375 is a multifunctional miRNA participating in pancreatic islet development, glucose homeostasis, mucosal immunity, lung surfactant secretion and more importantly, tumorigenesis. Recently, miR-375 has been found significantly downregulated in multiple types of cancer, and suppresses core hallmarks of cancer by targeting several important oncogenes like AEG-1, YAP1, IGF1R and PDK1. The alteration of miR-375 in cancer is caused by a variety of mechanisms, including the dysregulation of transcription factors, aberrant promoter methylation and so on. Reduced expression of miR-375 in tissue or circulation may indicate the presence of neoplasia as well as a poor prognosis of many malignant cancers. Moreover, miR-375 stands for a promising direction for developing targeted therapies due to its capacity to inhibit tumor cell growth in vitro and in vivo. Here, we summarize the present understanding of the tumor suppressive role of miR-375 in cancer progression; the mechanisms underlying the dysregulation of miR-375; the potential use of miR-375 in prognosis and diagnosis and the therapeutic prospects of miR-375 in cancer.

Developing epigenetic diagnostics and therapeutics for brain disorders

Perturbations in epigenetic mechanisms have emerged as cardinal features in the molecular pathology of major classes of brain disorders. We therefore highlight evidence which suggests that specific epigenetic signatures measurable in central - and possibly even in peripheral tissues - have significant value as translatable biomarkers for screening, early diagnosis, and prognostication; developing molecularly targeted medicines; and monitoring disease progression and treatment responses. We also draw attention to existing and novel therapeutic approaches directed at epigenetic factors and mechanisms, including strategies for modulating enzymes that write and erase DNA methylation and histone/chromatin marks; protein-protein interactions responsible for reading epigenetic marks; and non-coding RNA pathways.

MicroRNA-650 expression in glioma is associated with prognosis of patients

MicroRNAs are known as non-coding RNAs that regulate the expression of target mRNA. Accumulating evidence has indicated that microRNA expression in human malignancies can be utilized as a prognostic marker for patients. However, the prognostic value of miR-650 in human glioma has not been investigated yet. In the present investigation, we have recruited 168 cases glioma specimens and 21 normal control brain specimens. Quantitative real-time PCR was carried out to investigate the expression of miR-650. Kaplan-Meier analysis and Cox's proportional hazards model was used to evaluate the association of miR-650 with prognosis of glioma patients. Results showed that miR-650 expression was increased in glioma compared with normal control specimens (P < 0.001). It was also found that miR-650 expression was related to World Health Organization grade and Karnofsky performance score (KPS) for high expression was more frequently detected in glioma of high grade or low KPS score (P < 0.001). The prognosis of glioma with high miR-650 expression was significantly worse compared with that of glioma with low miR-650 expression. These results proved that miR-650 expression was a significant prognostic indicator in glioma, which may suggest new management of human glioma.