microRNAs as novel epigenetic biomarkers for human cancer

The miR-199a-5p/HIF1α dual-regulatory axis participates in hypoxia-induced aggressive phenotypes of oral squamous cell carcinoma (OSCC) cells

BACKGROUND

The late-stage diagnosis and distant metastasis of oral squamous cell carcinoma (OSCC) remain a huge challenge to clinical treatment for OSCC. During the past decades, targeting glycolysis-inducing factors becomes an attractive new strategy in OSCC therapies.

METHODS

OSCC cells were stimulated with hypoxia or transfected with agomir-199a-5p, antagomir-199a-5p, and siRNA for HIF1A, cell proliferation was detected by CCK-8 assay; HIF1α, GLUT1, HK2 and LDHA expression levels were examined with western blot; miR-199 expression was determined with RT-PCR; cell migratory and invasive abilities were examined using wound healing and transwell assays; the lactate and glucose in culture medium were also determined. Luciferase assay or CHIP assay was applied for confirm the binding between miR-199a-5p and HIF1A 3'UTR, or between HIF1α and miR-199a promoter.

RESULTS

HIF1α showed to be abnormally up-regulated, and miR-199a-5p showed to be abnormally down-regulated within OSCC under hypoxia. Hypoxia considerably enhanced OSCC cell proliferation, glycolysis, migratory ability, and invasive ability. MiR-199a-5p bound to HIF1A 3'-UTR and suppressed HIF1A expression; HIF1α targeted miR-199a-5p promoter region and downregulated miR-199a-5p expression. Under hypoxia, miR-199a-5p overexpression significantly repressed HIF1α up-regulation inresponse to hypoxia, OSCC cell proliferation, glycolysis, migratory ability, and invasive ability.

CONCLUSION

miR-199a-5p and HIF1α form a dual-regulatory axis in OSCC cells; the miR-199a-5p/HIF1α dual-regulatory axis contributes to hypoxia-induced aggressive OSCC phenotypes.

Prognostic implication of downregulated exosomal miRNAs in patients with sepsis: a cross-sectional study with bioinformatics analysis

BACKGROUND

Despite the understanding of sepsis-induced extracellular vesicles (EVs), such as exosomes, and their role in intercellular communication during sepsis, little is known about EV contents such as microRNA (miRNA), which modulate important cellular processes contributing to sepsis in body fluids. This study aimed to analyze the differential expression of exosomal miRNAs in plasma samples collected from sepsis patients and healthy controls, and to identify potential miRNA regulatory pathways contributing to sepsis pathogenesis.

METHODS

Quantitative real-time PCR-based microarrays were used to profile plasma exosomal miRNA expression levels in 135 patients with sepsis and 11 healthy controls from an ongoing prospective registry of critically ill adult patients admitted to the intensive care unit. The identified exosomal miRNAs were tested in an external validation cohort (35 sepsis patients and 10 healthy controls). And then, functional enrichment analyses of gene ontology, KEGG pathway analysis, and protein-protein interaction network and cluster analyses were performed based on the potential target genes of the grouped miRNAs. Finally, to evaluate the performance of the identified exosomal miRNAs in predicting in-hospital and 90-day mortalities of sepsis patients, receiver operating characteristic curve (ROC) and Kaplan-Meier analyses were performed.

RESULTS

Compared with healthy controls, plasma exosomes from sepsis patients showed significant changes in 25 miRNAs; eight miRNAs were upregulated and 17 downregulated. Additionally, the levels of hsa-let-7f-5p, miR-331-3p miR-301a-3p, and miR-335-5p were significantly lower in sepsis patients than in healthy controls (p < 0.0001). These four miRNAs were confirmed in an external validation cohort. In addition, the most common pathway for these four miRNAs were PI3K-Akt and mitogen-activated protein kinase (MAPK) signaling pathways based on the KEGG analysis. The area under the ROC of hsa-let-7f-5p, miR-331-3p, miR-301a-3p, and miR-335-5p level for in-hospital mortality was 0.913, 0.931, 0.929, and 0.957, respectively (p < 0.001), as confirmed in an external validation cohort. Also, the Kaplan-Meier analysis showed a significant difference in 90-day mortality between sepsis patients with high and low miR-335-5p, miR-301a-3p, hsa-let-7f-5p, and miR-331-3p levels (p < 0.001, log-rank test).

CONCLUSION

Among the differentially-expressed miRNAs detected in microarrays, the top four downregulated exosomal miRNAs (hsa-let-7f-5p, miR-331-3p miR-301a-3p, and miR-335-5p) were identified as independent prognostic factors for in-hospital and 90-day mortalities among sepsis patients. Bioinformatics analysis demonstrated that these four microRNAs might provide a significant contribution to sepsis pathogenesis through PI3K-Akt and MAPK signaling pathway.

MiRNA-144-5p down-modulates CDCA3 to regulate proliferation and apoptosis of lung adenocarcinoma cells

BACKGROUND

Lung adenocarcinoma (LUAD) belongs to non-small cell lung cancer. In addition to surgical resection, chemotherapy and radiotherapy cause great side effects and low 5-year survival rates. MiRNAs are closely related to cancer development. This study aimed to analyze the molecular mechanism of miRNA-144-5p targeting CDCA3 to inhibit LUAD proliferation.

METHODS

MiRNA and mRNA data were downloaded from TCGA-LUAD dataset for differential expression analysis. TargetScan and miRTarBase databases were adopted to predict the target genes of miRNA, and the signaling pathways involved were analyzed by gene set enrichment analysis. The functions of LUAD cells were analyzed by CCK-8, colony formation assay, stem cell spheroidization assay, and flow cytometry. The expression levels of CDCA3, p53, and cell cycle-associated proteins were evaluated by Western blot.

RESULTS

The expression of miRNA-144-5p was significantly down-regulated in LUAD, but overexpression of it repressed proliferation and spheroidization, and promoted apoptosis of LUAD cells. By bioinformatics prediction and dual-luciferase reporter assay, miRNA-144-5p was validated to target CDCA3, thereby regulating proliferation of LUAD cells. Besides, the results of cell experiments showed that miRNA-144-5p targeting CDCA3 affected cell proliferation and apoptosis in LUAD by regulating cell cycles, and miRNA-144-5p/CDCA3 mediated the p53 signaling pathway to affect the growth of LUAD cells.

SIGNIFICANCE

Through the study of the pathogenesis of miRNA-144-5p regulating LUAD, we can better understand the molecular mechanism underlying LUAD development.

MicroRNA-129-1-3p Represses the Progression of Triple-Negative Breast Cancer by Targeting the GRIN2D Gene

The aberrant expression of miRNA is strongly linked to numerous stages of triple-negative breast cancer (TNBC) progression, and it plays an indispensable role in the process from tumor onset and progress to invasion and metastasis. In this study, we first transfected miR-129-1-3p mimics and inhibitor into MDA-MB-231 TNBC cells, respectively. Then, we assessed the pathological role of miR-129-1-3p in MDA-MB-231 cells. The results showed that miR-129-1-3p were successfully inserted into MDA-MB-231 cells. Besides, miR-129-1-3p could distinctively repress the growth, migration along with infiltration of MDA-MB-231 cells, which might be related to the inhibition of GRIN2D expression. Our results indicate that miR-129-1-3p was illustrated to serve as a tumor repressor via targeting GRIN2D in TNBC cells and highlight that the restoration of miR-129-1-3p might be a new treatment target for TNBC.

Long non-coding RNA MALAT1 regulates oxaliplatin-resistance via miR-324-3p/ADAM17 axis in colorectal cancer cells

Background

Colorectal cancer (CRC) is one of the most general malignant tumors. Accumulating evidence implied that long non-coding RNA Metastasis Associated Lung Adenocarcinoma Transcript 1 (MALAT1) participated in the tumorigenesis of CRC. However, the effect of MALAT1 in drug-resistance needed to be further illustrated.

Methods

Levels of MALAT1, microRNA (miR)-324-3p, and a disintegrin and metalloprotease metallopeptidase domain 17 (ADAM17) were detected using quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assay. Cell Counting Kit 8 (CCK-8) was used to assess the half maximal inhibitory concentration (IC50) of oxaliplatin (Ox). Meanwhile, cell proliferation, migration and apoptosis were detected by CCK-8, transwell assay, and flow cytometry, respectively. The interaction between miR-324-3p and MALAT1 or ADAM17 was clarified by dual-luciferase reporter assay. Also, the effect of MALAT1 on tumor growth was detected in xenograft tumor mice treated with Ox.

Results

Significant up regulation of MALAT1 and ADAM17, and decrease of miR-324-3p were observed in Ox-resistant CRC tissues and cells. MALAT1 deficiency enhanced the sensitivity of Ox-resistant CRC cells response to Ox, while miR-324-3p repression or ADAM17 acceleration could overturn this effect. Moreover, MALAT1 silencing repressed tumor growth in Ox-treated nude mice. Mechanically, MALAT1 exerted promotion effect on the resistance response to Ox via miR-324-3p/ADAM17 axis in Ox-resistant CRC cells.

Conclusion

MALAT1 modulated the sensitivity of Ox through ADAM17 in Ox-resistant CRC cells by sponging miR-324-3p, thus MALAT1 might serve as a novel insight for the therapy of CRC.

MiR-342-3p inhibits cell migration and invasion through suppressing forkhead box protein Q1 in ovarian carcinoma

Previous studies have shown that microRNAs are involved in the pathogenesis of ovarian carcinoma (OC). However, the abnormal expression and function of miR-342-3p have not been reported in OC. Therefore, this research was designed to explore its role in OC. In this study, qRT-PCR assay showed that the expression level of miR-342-3p was reduced in OC tissues and cell lines. Functionally, Transwell assay suggested that overexpression of miR-342-3p suppressed cell migration and invasion in OC. In addition, forkhead box protein Q1 (FOXQ1) was confirmed to be a direct target gene by luciferase activity assay. Furthermore, FOXQ1 was found to be upregulated and function as an oncogene in OC. More importantly, miR-342-3p was negatively correlated with FOXQ1 expression in OC tissues. Furthermore, overexpression of FOXQ1 could partially rescue inhibitory effect of miR-342-3p on cell migration and invasion in OC. In brief, we concluded that miR-342-3p inhibited migration and invasion of OC cells through suppressing FOXQ1 expression.

MicroRNA-769-5p suppresses cell growth and migration via targeting NUSAP1 in bladder cancer

BACKGROUND

Nucleolar and spindle-associated protein 1 (NUSAP1) has been identified to be strongly implicated in the carcinogenesis of cervical carcinoma, breast cancer, and liver cancer, and shows a high expression level in bladder cancer, indicating that NUSAP1 might be a potent target for cancer treatment. Using bioinformatics methods, we found that NUSAP1 was a putative target of miR-769-5p. Here, we aimed to explore whether miR-769-5p is involved in bladder cancer progression via targeting NUSAP1.

METHODS

MiR-769-5p expression patterns in bladder cancer tissues and cells were detected by RT-PCR. Kaplan-Meier was used to determine the clinical effects of miR-769-5p expression levels on the overall survival of bladder cancer patients. Bioinformatics methods were used to predict the binding sites between miR-769-5p and NUSAP1, which was verified by the luciferase gene reporter assay. CCK-8, flow cytometry, wound healing and transwell chamber experiments were performed to test cell growth, apoptosis, migration and invasion capacities.

RESULTS

miR-769-5p was lowly expressed in bladder cancer tissues and cells, which was closely associated with poor prognosis. Overexpression of miR-769-5p induced significant repressions in cell growth, migration, and invasion and caused an obvious increase in cell apoptosis, whereas these tendencies were reversed when NUSAP1 was upregulated.

CONCLUSION

This study demonstrates that miR-769-5p functions as a tumor suppressor in bladder cancer via targeting NUSAP1.

Effect of down-regulation of miR-221 on cell proliferation and cisplatin sensitivity in cisplatin-resistant gastric cancer cells and underlying mechanism

BACKGROUND

Patients with advanced gastric cancer (GC) usually undergo chemotherapy as the primary treatment. However, the effectiveness of chemotherapy is often limited by the development of drug resistance in GC cells. This study aimed to investigate the expression pattern, biological role, and potential mechanism of microRNA-221 (miR-221) in cisplatin (DDP)-resistant GC cells, in order to provide a reference for clinical treatment of this malignancy.

AIM

To investigate the effect of down-regulation of miR-221 on cell proliferation and DDP sensitivity in DDP-resistant GC cells and to explore the underlying mechanism.

METHODS

AGS and MGC-803 cells were screened for DDP-resistant cells (AGS/DDP and MGC-803/DDP). The expression levels of miR-221 in GC tissues, matched tumor adjacent tissues, DDP-sensitive tissues, DDP-resistant tissues, GC cells, and DDP-resistant GC cells were detected by RT-PCR. After AGS/DDP and MGC-803/DDP cells were transfected with LV-miR-221-shRNA, cell proliferation and DDP sensitivity in those cells were measured by MTT assay, cell apoptosis was detected by Annexin V-FITC/PI staining, and the mRNA and protein expression of CCND1 was detected by RT-qPCR and Western blot, respectively. The potential target genes of miR-221 were predicted by bioinformatics analysis.

RESULTS

The expression of miR-221 was up-regulated in GC tissues and gastric cells, especially in DDP-resistant tissues and DDP-resistant GC cells. Down-regulation of miR-221 inhibited the proliferation of AGS/DDP and MGC-803/DDP cells, but increased their apoptosis and chemosensitivity to DDP. CCND1 was found to be a direct target gene of miR-221. Transfection with LV-miR-221-shRNA inhibited the mRNA and protein expression of CCND1.

CONCLUSION

Down-regulation of miR-221 can inhibit cell proliferation and promote chemosensitivity to DDP in DDP-resistant GC cells, which may be achieved by inhibiting the expression of its target gene CCND1.

Inhibition of MALAT1 reduces tumor growth and metastasis and promotes drug sensitivity in colorectal cancer

Human metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long non-coding RNA known to be highly expressed in several tumors. In colorectal cancer (CRC), MALAT1 promotes cell proliferation, metastasis, and invasion in vitro and in vivo. This study aimed to investigate the effect of MALAT1 on the proliferation, migration, and drug sensitivity of CRC cells in vitro and in vivo and the mechanisms involved therein. We observed increased expression of MALAT1 in six CRC cell lines compared to that in normal cells, suggesting its involvement in CRC progression. Downregulation of MALAT1 inhibited cell migration and induced apoptosis in vitro and inhibited tumor growth and metastasis in nude mice. Furthermore, MALAT1 silencing downregulated the expression of ATP-binding cassette transporters (ABC), breast cancer resistance protein (BCRP), and multi-drug resistance proteins including MDR1 and MRP1, resulting in decreased resistance of cancer cells to 5-FU. In addition, the metastasis and invasion of HCT-116 and HCT-116/5-FU cells were regulated via targeting miR-20b-5p. Based on these observations, we infer that inhibition of MALAT1 suppressed CRC progression and metastasis and improved the sensitivity of cancer cells to 5-FU. The present study proposes a new direction to investigate the molecular mechanisms underlying the invasion and metastasis of CRC, whereby the interaction between MALAT1 and miR-20b-5p could be a novel therapeutic target for CRC.

miR-199b-5p serves as a tumor suppressor in renal cell carcinoma

MicroRNA (miR)-199b-5p has been reported to have a critical role in various types of malignancy. However, the exact function miR-199b-5p in renal cancer remains to be fully elucidated. The present study aimed to detect the expression levels of miR-199b-5p in renal cell carcinoma (RCC) tissues and RCC cell lines, and investigated the effect of miR-199b-5p in vitro with Cell Counting Kit-8, MTT, scratch wound, Transwell and flow cytometric assays. The results demonstrated that the expression levels of miR-199b-5p were significantly downregulated in RCC tissues and cell lines compared with those in paired adjacent normal renal tissues and a reference cell line, respectively. Downregulation of miR-199b-5p by transfection with a synthetic inhibitor promoted cellular proliferation and migration, while reducing the apoptotic rate, indicating that miR-199b-5p may serve as a tumor suppressor in RCC. Further study is required to identify target genes of miR-199b-5p to elucidate the mechanisms underlying the role of miR-199b-5p in the occurrence and development of RCC.

Up-Regulation of miR-21, miR-25, miR-93, and miR-106b in Gastric Cancer

Background:

Differential expression profile of microRNAs (miRNAs) could be a diagnosis signature for monitoring gastric cancer (GC) progression. In this study, we focus on the comparison of expression levels of miR-21, miR-25, miR-93, miR-106b, and miR-375 during the sequential pattern of GC development, including normal gastric, gastric dysplasia, and GC sample.

Methods:

We used SYBR Green-based quantitative-PCR to quantify miRNAs expression.

Results:

Our analysis revealed the increased expression levels of miR-21 (p = 0.034), miR-25 (p = 0.0003), miR-93 (p = 0.0406), and miR-106b (p = 0.023) in GC samples. In addition, GC patients with positive lymph node metastasis showed the up-regulation of miR-25, miR-93, and miR-106b (p < 0.05).

Conclusion:

Our findings suggested that the expression of miR-21, miR-25, miR-93, and miR-106b altered in GC, and some of them may be further investigated as biomarkers for GC early detection and prognosis prediction.

MicroRNA‑433 reduces cell proliferation and invasion in non‑small cell lung cancer via directly targeting E2F transcription factor 3

MicroRNAs (miRNA/miRs) have been associated with the initiation and progression of non‑small‑cell lung cancer (NSCLC). Hence, a comprehensive understanding of the association between dysregulated miRNAs and NSCLC may contribute to the identification of novel therapeutic methods for patients with NSCLC. MiRNA‑433 (miR‑433) has been reported to be dysregulated in numerous types of human cancers; however, its expression pattern, biological roles and associated mechanisms in NSCLC require further investigation. The present study aimed to detect miR‑433 expression and determine its roles and underlying molecular mechanisms in NSCLC. In the present study, reverse transcription‑quantitative polymerase chain reaction revealed that miR‑433 was significantly downregulated in NSCLC tissues and cell lines. This decreased miR‑433 expression was strongly associated with the tumor node metastasis stage and lymph node metastasis of patients with NSCLC. Cell Counting kit‑8 and cell invasion assays revealed that the resumption of miR‑433 expression decreased the proliferation and invasion of NSCLC cells. Bioinformatics analysis predicted E2F transcription factor 3 (E2F3) as a potential target of miR‑433. Luciferase reporter assay, RT‑qPCR and western blot analysis further demonstrated that E2F3 was a direct target of miR‑433 in NSCLC. E2F3 downregulation induced by small interfering RNA exhibited inhibitory effects similar to those of miR‑433 overexpression in NSCLC cells, and the restored E2F3 expression counteracted the suppressive effects on NSCLC cells induced by miR‑433 overexpression. Therefore, miR‑433 may inhibit the progression of NSCLC, at least in part, by targeting E2F3. The present study indicated that miR‑433 may be investigated as an innovative candidate target for the therapy of patients with this fatal disease.

MicroRNA‑539 inhibits the proliferation and invasion of bladder cancer cells by regulating IGF‑1R

Bladder cancer is the most frequent malignancy of the urinary tract and the seventh most common cancer worldwide. The abnormal expression of microRNAs has been frequently observed in various types of human cancers, including bladder cancer. In addition, an increasing body of evidence has demonstrated that microRNAs are potential targets for cancer diagnosis, treatments and prognosis. The aim of the present study was to investigate the expression patterns and potential roles of microRNA‑539 (miR‑539) in bladder cancer and its underlying mechanism. Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) was performed to detect miR‑539 expression in the bladder cancer tissues and cell lines. Following transfection, MTT and cell invasion assays were used to investigate the effects of miR‑539 overexpression or IGF1R underexpression on bladder cancer cell proliferation and invasion. Bioinformatics analysis, a luciferase reporter assay, RT‑qPCR and western blot analysis were utilized to determine the potential targets of miR‑539 in bladder cancer. The results revealed that miR‑539 levels were relatively decreased in bladder cancer tissues and cell lines when compared with those observed in the matched adjacent normal bladder tissues and normal bladder epithelial cell line. miR‑539 expression was associated with the tumor stage and lymph node metastasis of patients with bladder cancer. In addition, the expression of miR‑539 suppressed bladder cancer cell proliferation and invasion. Insulin like growth factor 1 receptor (IGF‑1R) was identified as a direct target of miR‑539, and miR‑539 was also observed to regulate the protein kinase B and extracellular signal‑regulated kinases signaling pathways. IGF‑1R was markedly upregulated in bladder cancer tissues and negatively associated with miR‑539 expression levels. Furthermore, IGF‑1R knockdown in bladder cancer cells significantly inhibited cell proliferation and invasion. To the best of our knowledge, these results demonstrated for the first time that miR‑539 may act as a tumor suppressor and serve important roles in tumorigenesis and progression of bladder cancer. Thus, miR‑539/IGF‑1R may be a potential therapeutic target for the treatment of bladder cancer.

Angiogenesis: Managing the Culprits behind Tumorigenesis and Metastasis

Deregulated angiogenesis has been identified as a key contributor in a number of pathological conditions including cancer. It is a complex process, which involves highly regulated interaction of multiple signalling molecules. The pro-angiogenic signalling molecule, vascular endothelial growth factor (VEGF) and its cognate receptor 2 (VEGFR-2), which is often highly expressed in majority of human cancers, plays a central role in tumour angiogenesis. Owing to the importance of tumour vasculature in carcinogenesis, tumour blood vessels have emerged as an excellent therapeutic target. The anti-angiogenic therapies have been shown to arrest growth of solid tumours through multiple mechanisms, halting the expansion of tumour vasculature and transient normalization of tumour vasculature which help in the improvement of blood flow resulting in more uniform delivery of cytotoxic agents to the core of tumour mass. This also helps in reduction of hypoxia and interstitial pressure leading to reduced chemotherapy resistance and more uniform delivery of cytotoxic agents at the targeted site. Thus, complimentary combination of different agents that target multiple molecules in the angiogenic cascade may optimize inhibition of angiogenesis and improve clinical benefit in the cancer patients. This review provides an update on the current trend in exploitation of angiogenesis pathways as a strategy in the treatment of cancer.

MicroRNA-623 Targets Cyclin D1 to Inhibit Cell Proliferation and Enhance the Chemosensitivity of Cells to 5-Fluorouracil in Gastric Cancer

The dysregulation of microRNAs (miRNAs) plays an important function in the onset and progression of gastric cancer (GC). In addition, aberrantly expressed miRNAs affect the chemosensitivity of GC cells to chemotherapeutic drugs. Hence, miRNA-based targeted therapy might be applied to treat patients with GC exhibiting chemotherapeutic resistance. In this study, miRNA-623 (miR-623) expression was downregulated in GC tissues and cell lines. Functional analysis showed that the restored miR-623 expression could inhibit the proliferation of GC cells and enhance their chemosensitivity to 5-FU via the cell apoptosis pathway. Cyclin D1 (CCND1) was identified as a direct target gene of miR-623 in GC. The overexpressed CCND1 in GC tissues was negatively correlated with miR-623 level. The recovered CCND1 expression counteracted the effects of miR-623 on GC cell proliferation, chemosensitivity, and 5-FU-induced apoptosis. Thus, our results suggest that miR-623 might function as a tumor suppressor in GC and could be a promising therapeutic target for patients with GC, especially those with chemotherapeutic resistance.

Identification of miRNAs as biomarkers for acquired endocrine resistance in breast cancer

Therapies targeting estrogen receptor α (ERα) including tamoxifen, a selective estrogen receptor modulator (SERM) and aromatase inhibitors (AI), e.g., letrozole, have proven successful in reducing the death rate for breast cancer patients whose initial tumors express ERα. However, about 40% of patients develop acquired resistance to these endocrine treatments. There is a critical need to develop sensitive circulating biomarkers that accurately identify signaling pathways altered in breast cancer patients resistant to endocrine therapies. Serum miRNAs have the potential to serve as biomarkers of the progression of endocrine-resistant breast cancer due to their cancer-specific expression and stability. Exosomal transfer of miRNAs has been implicated in metastasis and endocrine-resistance. This review focuses on miRNAs in breast tumors and in serum, including exosomes, from breast cancer patients that are associated with resistance to tamoxifen since it is best-studied.

MicroRNA-154 inhibits the growth and metastasis of gastric cancer cells by directly targeting MTDH

MicroRNAs (miRNAs) are a group of non-protein-coding, highly conserved single-stranded RNA molecules. The abnormal expression of miRNAs has been demonstrated to have an important function in the carcinogenesis and progression of gastric cancer. microRNA-154 (miR-154) has been reported to be downregulated in non-small cell lung, colorectal and prostate cancer. However, the expression and roles of miR-154 in gastric cancer remain to be established. The present study measured the expression levels of miR-154 in gastric cancer tissues and cell lines. miR-154 was found to be significantly downregulated in gastric cancer tissues and cell lines. In addition, functional studies indicated that the overexpression of miR-154 inhibited the proliferation, migration and invasion of gastric cancer cells. Using TargetScan, a dual luciferase reporter assay, reverse transcription-quantitative polymerase chain reaction and western blot analysis, metadherin (MTDH) was revealed as a novel miR-154 target. In addition, knocking down MTDH lead to a similar effect as overexpressing-154 in gastric cells. The present findings indicate that miR-154 was downregulated in gastric cancer, and inhibited tumor behaviors of gastric cancer cells partially through the downregulation of MTDH. Therefore, the miR-154/MTDH axis may be a novel therapeutic to treat patients with gastric cancer.

MeCP2, a target of miR-638, facilitates gastric cancer cell proliferation through activation of the MEK1/2-ERK1/2 signaling pathway by upregulating GIT1

Methyl-CpG binding protein 2 (MeCP2) is involved in the carcinogenesis and progression of multiple types of cancer. However, its precise role in gastric cancer (GC) and the relevant molecular mechanism remain unknown. In the present study, we found that miR-638 levels were lower in GC tissues and GC cell lines than in adjacent normal tissues and normal gastric epithelial cell lines, respectively. Low miR-638 levels were associated with poor tumor differentiation, tumor size and lymph node metastasis. MeCP2 expression levels were higher in GC tissues than in adjacent normal tissues. It was found that miR-638 inhibited GC cell proliferation, colony formation, G1–S transition and tumor growth, and induced cell apoptosis by directly targeting MeCP2. MeCP2 promoted GC cell proliferation, colony formation and G1–S cell-cycle transition, and suppressed apoptosis. Molecular mechanistic investigations were performed using an integrated approach with a combination of microarray analysis, chromatin immunoprecipitation sequencing and a reporter gene assay. The results showed that MeCP2 bound to the methylated CpG islands of G-protein-coupled receptor kinase-interacting protein 1 (GIT1) promoter and upregulated its expression, thereby activating the MEK1/2–ERK1/2 signaling pathway and promoting GC cell proliferation. Taken together, our study demonstrates that MeCP2, a target of miR-638, facilitates GC cell proliferation and induces cell-cycle progression through activation of the MEK1/2–ERK1/2 signaling pathway by upregulating GIT1. The findings suggest that MeCP2 plays a significant role in GC progression, and may serve as a potential target for GC therapy.

miR-410-3p suppresses breast cancer progression by targeting Snail

miR-410-3p acts as an oncogene or tumor-suppressor gene in various types of cancer. However, its role in breast cancer remains unknown. In the present study, expression of miR-410-3p in 30 breast cancer and paired adjacent normal tissues was detected by RT-qPCR. The expression of miR-410-3p was downregulated in 76.7% of the breast cancer samples. To further validate the expression of miR-410-3p in breast cancer, we analyzed miR-410-3p expression profiling data set from The Cancer Genome Atlas (TCGA) including 683 breast cancer and 87 normal breast tissues. We observed that the expression of miR-410-3p was downregulated in breast cancer tissues. Next, we investigated the influence of miR-410-3p on cell proliferation by transiently transfecting the miR-410-3p mimic or inhibitor, as well as their corresponding controls in the MDA-MB-231 and MCF7 cell lines. miR-410-3p overexpression reduced cell growth, colony formation and the number of EdU-positive cells in the MDA-MB-231 cells. In contrast, inhibition of miR-410-3p in the MCF7 cells resulted in a higher proliferation rate as assessed by MTT assay, plate colony formation and EdU assays. Furthermore, miR-410-3p inhibited epithelial-mesenchymal transition. In addition, Snail was found to be a direct target of miR-410-3p based on a luciferase assay. Overexpression of Snail was able to rescue the effect of miR-410-3p in breast cancer cells. Moreover, miR‑410-3p was inversely expressed with Snail in breast cancer samples. Our data provide new knowledge regarding the role of miR-410-3p in breast cancer progression.

Clinical significance of upregulation of mir-196a-5p in gastric cancer and enriched KEGG pathway analysis of target genes

BACKGROUND

miRNAs are relatively recently discovered cancer biomarkers which have important implications for cancer early diagnosis, treatment and estimation of prognosis. Here we focussed on expression of mir-196a-5p in gastric cancer tissues and cell lines so as to analyse its significance for clinicopathologic characteristics and generate enriched KEGG pathways clustered by target genes for exploring its potential roles as a biomarker in gastric cancer.

MATERIALS AND METHODS

The expression of mir-196a-5p in poorly, moderate and well differentiated gastric cancer cell lines compared with GES-1 was detected by RT-qPCR, and the expression of mir-196a-5p in gastric cancer tissues comparing with adjacent non cancer tissues of 58 cases were also assessed by RT- qPCR. Subsequently, an analysis of clinical significance of mir-196a-5p in gastric cancer and enriched KEGG pathways was executed based on the miRWalk prediction database combined with bioinformatics tools DAVID 6.7 and Mirfocus 3.0.

RESULTS

RT-qPCR showed that mir-196a-5p was up-regulated in 6 poorly and moderate differentiated gastric cancer cell lines SGC-7901, MKN-45, MKN-28, MGC-803, BGC-823, HGC-27 compared with GES-1, but down-regulated in the highly differentiated gastric cancer cell line AGS. Clinical data indicated mir-196a-5p to beup-regulated in gastric cancer tissues (47/58). Overexpression of mir-196a-5p was associated with more extensive degree of lymph node metastasis and clinical stage (P <0.05; x2 test). Enriched KEGG pathway analyses of predicted and validated targets in miRWalk combined with DAVID 6.7 and Mirfocus 3.0 showed that the targeted genes regulated by mir-196a-5p were involved in malignancy associated biology.

CONCLUSIONS

Overexpression of mir-196a-5p is associated with lymph node metastasis and clinical stage, and enriched KEGG pathway analyses showed that targeted genes regulated by mir-196a-5p may contribute to tumorgenesis, suggesting roles as an oncogenic miRNA biomarker in gastric cancer.

Expression and mechanism of microRNA-181A on incidence and survival in late liver metastases of colorectal cancer

The emerging role of microRNA-181A (miR-181A) in CRC patients with late liver metastases was studied. In the present study we investigated the association between expression and mechanism of miRNA-181A, liver metastasis and prognosis of colorectal cancer (CRC). The expression of miR-181A and PTEN in CRC patients with late liver metastases was higher than that of the normal (control) group, whereas the expression of miR-181A and PTEN was lower in all pathological groups (TNM I-TNM IV). Overall survival (OS) of lower expression miR-181A CRC patients with late liver metastases was higher than that of higher expression miR-181A CRC patients with late liver metastases. The expression of miR-181A and PTEN in the colon cell line NCM460 was lower than that of the colon cancer SW620 cell line. Upregulation of miR-181A promoted cell viability and inhibited apoptosis of SW620 cells, suppressed PTEN expression and activated phosphorylation of AKT (p-AKT) in SW620 cells. Additionally, downregulation of miR-181A inhibited cell viability of SW620 cells through promotion of PTEN and inhibition of p-AKT. Together, our results indicate that miR-181A expression is associated with CRC patients with late liver metastases through PTEN/AKT signaling.

Roles for miRNAs in endocrine resistance in breast cancer

Therapies targeting estrogen receptor alpha (ERα), including selective ER modulators such as tamoxifen, selective ER downregulators such as fulvestrant (ICI 182 780), and aromatase inhibitors such as letrozole, are successfully used in treating breast cancer patients whose initial tumor expresses ERα. Unfortunately, the effectiveness of endocrine therapies is limited by acquired resistance. The role of microRNAs (miRNAs) in the progression of endocrine-resistant breast cancer is of keen interest in developing biomarkers and therapies to counter metastatic disease. This review focuses on miRNAs implicated as disruptors of antiestrogen therapies, their bona fide gene targets and associated pathways promoting endocrine resistance.

An electrochemiluminescent microRNA biosensor based on hybridization chain reaction coupled with hemin as the signal enhancer

In this study, a new universal biosensor based on luminol anodic electrochemiluminescence (ECL) for the detection of microRNA-155 was constructed by using hydrogen peroxide (H2O2) as a co-reactant and hemin as a catalyzer for signal amplification. The bare glassy carbon electrode (GCE) was first electrodeposited with Au nanoparticles (AuNPs). Then, helper DNA, which was partly complementary with the hairpin DNA chains, was assembled on the prepared GCE. Target microRNA-155 and the hairpin hybridization chains could create a formation of extended double-stranded DNA (dsDNA) polymers through the displacement of hybridization chains and the hybridization chain reaction (HCR). The HCR-generated dsDNA polymers give rise to the intercalation of a lot of hemin which could catalyze the oxidation of H2O2, leading to a remarkably amplified ECL signal output. The proposed biosensor showed a wide linear range from 5 fM to 50 pM with a relatively low detection limit of 1.67 fM for microRNA-155 detection. With excellent selectivity, good stability and high sensitivity, the proposed biosensor is promising in the development of a high-throughput assay of microRNA-155.

Differential distribution of microRNAs in breast cancer grouped by clinicopathological subtypes

BACKGROUND

microRNAs (miRNAs) that regulate proliferation, invasion and metastasis are considered to be the principal molecular basis of tumor heterogeneity. Breast cancer is not a homogeneous tissue. Thus, it is very important to perform microarray-based miRNA screening of tumors at different sites.

METHODS

Breast tissue samples from the centers and edges of tumors of 30 patients were classified into 5 clinicopathological subtypes. In each group, 6 specimens were examined by microRNA array. All differential miRNAs were analyzed between the edges and centers of the tumors.

RESULTS

Seventeen kinds of miRNAs were heterogeneously distributed in the tumors from different clinicopathological subtypes that included 1 kind of miRNA in Luminal A and Luminal B Her2+ subtypes, 4 kinds in Luminal A and Her2 overexpression subtypes, 6 kinds in Luminal B Ki67+ and Luminal B Her2+ subtypes, 2 kinds between Luminal B Ki67+ and triple-negative breast cancer (TNBC) subtypes, 2 kinds between Luminal B Her2+ and TNBC subtypes, and 2 kinds between Luminal B Ki67+, Luminal B Her2+, and TNBC subtypes. Twenty kinds of miRNAs were homogenously distributed in the tumors from different clinicopathological subtypes that included 6 kinds of miRNAs in Luminal B Ki67+ and Luminal B Her2+ subtypes, 1 kind in Luminal B Ki67+ and Her2 overexpression subtypes, 10 kinds between Luminal B Ki67+ and TNBC subtypes, 2 kinds in Luminal B Her2+ and TNBC subtypes, and 1 kind between Luminal B Ki67+, Luminal B Her2+, and TNBC subtypes.

CONCLUSIONS

A total of 37 miRNAs were significantly distributed in tumors from the centers to edges, and in all clinicopathological subtypes.

The clinical significance of downregulation of mir-124-3p, mir-146a-5p, mir-155-5p and mir-335-5p in gastric cancer tumorigenesis

Dysregulated miRNAs in gastric cancer are usually screened by miRNA microarray from clinical samples, however, reports have indicated that results of each miRNA microarray screening are considerably different, and dysregulated miRNAs, especially downregulated miRNAs were contradictory. In view of this, the Human Cancer Pathway Finder miRNA PCR array was applied to compare 7 gastric cancer cell lines AGS, SGC-7901, MKN-45, MKN-28, MGC-803, BCG-823, and HGC-27 with an immortalized normal gastric cell line, GES-1 in cancer pathway-related miRNA expression profile, followed by qPCR verification, the clinical significance of downregulated miRNAs and the Enriched KEGG pathways and GO terms of their target genes were analyzed. Thirty-eight miRNAs were upregulated, and four miRNAs were downregulated in gastric cancer cell lines. Clinical significance of 4 miRNAs including mir-124-3p, mir-146a-5p, mir-155-5p and mir-335-5p in gastric cancer tissue compared with adjacent non-tumor tissues of 58 patients indicated that the low-expression group of mir-124-3p, mir-146a-5p, mir-155-5p and mir-335-5p showed more extensive lymph node metastasis, lymphatic invasion, venous invasion, high-stage Borrmann type, lymphatic invasion and poor differentiation than that of the high-expression groups, respectively (P<0.05; χ² test). Enriched KEGG pathway analyses showed that most of the targeted genes of the 4 miRNAs concentrated on 37 signaling pathways, and were involved in the same pathways related to cancer. Enriched GO terms showed that targeted genes of the 4 miRNAs concentrated on 339 terms, 24 of 339 terms are associated with cancer tumorigenesis. The Human Cancer Pathway Finder miRNA PCR array could be used to screen dysregulated miRNAs effectively, and 4 screened miRNAs, mir-124-3p, mir-146a-5p, mir-155-5p and mir-335-5p were found to be downregulated in gastric cancer. Clinical significance and bioinformatic analysis on the target genes of these 4 miRNAs indicated that they were deeply involved in tumorigenesis, suggesting roles such as miRNA tumor suppressors in gastric cancer tumorigenesis which could be applied in gastric cancer diagnosis and prognosis.

miR-146a G>C polymorphisms and risk of hepatocellular carcinoma in a Chinese population

MicroRNAs (miRNAs) are thought to have a role in cancer development. We investigated the association among miR-146a G>C genetic variations, hepatitis B (HBV), and C (HCV) infection, and risk of hepatocellular carcinoma (HCC). Unconditional logistical regression analysis suggested that the miR-146a GG genotype and G allele carried a 2.10- (95 % confidence interval (CI)=1.03-4.37) and 1.42-fold (95 % CI=1.07-1.92) increased HCC risk, respectively. HBV-positive subjects carrying the miR-146a GG genotype (odds ratio (OR)=2.95, 95 % CI=1.31-6.81) and G allele (OR=1.65, 95 % CI=1.15-2.58) had an increased risk of HCC. However, the miR-146a GG genotype and G allele did not carry a significantly enhanced risk of HCC in either hepatitis-negative or HCV-infected subjects. miR-146a G>C polymorphisms appear to influence susceptibility to HCC, especially in HBV-infected patients.

MiR-106a targets Mcl-1 to suppress cisplatin resistance of ovarian cancer A2780 cells

Resistance to chemotherapy is a major obstacle for the effective treatment of advanced ovarian cancer. The mechanism of chemoresistance is still poorly understood. Recently, more and more evidence showed microRNAs (miRNAs) modulated many key molecules and pathways involved in chemotherapy. microRNA-106a (miR-106a) has been implicated in many cancers, but its role in ovarian cancer and drug resistance still remains unexplored. This study was to investigate whether miR-106a mediated resistance of the ovarian cancer cell line A2780 to the chemotherapeutic agent cisplatin (DDP). The different levels of miR-106a in A2780 cells and their resistant variant A2780/DDP cells were identified by using real-time PCR. MTT assay and flow cytometry were used to analyze the effect of miR-106a on cisplatin resistance of these paired cells. Real-time PCR, Western blotting and luciferase reporter assay were applied to explore whether Mcl-1 was a target of miR-106a. As compared to A2780 cells, the expression of miR-106a was down-regulated in the cisplatin resistant cell line A2780/DDP. Moreover, knockdown of miR-106a dramatically decreased antiproliferative effects and apoptosis induced by cisplatin in A2780 cells, while overexpression of miR-106a significantly increased antiproliferative effects and apoptosis induced by cisplatin in A2780/DDP cells. Furthermore, miR-106a inhibited cell survival and cisplatin resistance through downregulating the expression of Mcl-1. Mcl-1 was a direct target of miR-106a. These results suggest that miR-106a may provide a novel mechanism for understanding cisplatin resistance in ovarian cancer by modulating Mcl-1.

Endocrine resistance in breast cancer: Current status and a perspective on the roles of miRNAs (Review)

Current endocrine therapies for females with estrogen receptor-positive breast cancer have facilitated substantial improvements in outcomes. The effectiveness of endocrine therapy is limited by either initial de novo resistance or acquired endocrine resistance. Multiple mechanisms responsible for endocrine resistance have been proposed, including deregulation of various components of the estrogen receptor (ER) pathway, alterations in cell cycle and cell survival signaling molecules, and the activation of escape pathways. Dysregulation of miRNA expression has been associated with experimental and clinical endocrine therapy resistance. miRNAs are pivotal to understanding the complex biological mechanism of endocrine resistance, and may serve as novel candidate predictive and prognostic surrogates and therapeutic targets. This review focuses on current progress concerning the roles of miRNAs in endocrine resistance, and discusses the challenges and opportunities for implementing miRNA-based assays and treatment for patients with endocrine-resistant breast cancer.

A novel real-time PCR assay of microRNAs using S-Poly(T), a specific oligo(dT) reverse transcription primer with excellent sensitivity and specificity

Background

MicroRNAs (miRNAs) are small, non-coding RNAs capable of postranscriptionally regulating gene expression. Accurate expression profiling is crucial for understanding the biological roles of miRNAs, and exploring them as biomarkers of diseases.

Methodology/Principal Findings

A novel, highly sensitive, and reliable miRNA quantification approach,termed S-Poly(T) miRNA assay, is designed. In this assay, miRNAs are subjected to polyadenylation and reverse transcription with a S-Poly(T) primer that contains a universal reverse primer, a universal Taqman probe, an oligo(dT)₁₁ sequence and six miRNA-specific bases. Individual miRNAs are then amplified by a specific forward primer and a universal reverse primer, and the PCR products are detected by a universal Taqman probe. The S-Poly(T) assay showed a minimum of 4-fold increase in sensitivity as compared with the stem-loop or poly(A)-based methods. A remarkable specificity in discriminating among miRNAs with high sequence similarity was also obtained with this approach. Using this method, we profiled miRNAs in human pulmonary arterial smooth muscle cells (HPASMC) and identified 9 differentially expressed miRNAs associated with hypoxia treatment. Due to its outstanding sensitivity, the number of circulating miRNAs from normal human serum was significantly expanded from 368 to 518.

Conclusions/Significance

With excellent sensitivity, specificity, and high-throughput, the S-Poly(T) method provides a powerful tool for miRNAs quantification and identification of tissue- or disease-specific miRNA biomarkers.

The role of microRNAs in cancer: diagnostic and prognostic biomarkers and targets of therapies

INTRODUCTION

miRNAs are noncoding RNAs that target specific mRNA with subsequent regulation of particular genes, implicated in various biological processes. In cancer, miRNAs could show a different expression from normal tissues. miRNAs have a role as oncogenes when they target tumor suppressor genes and similarly they are tumor suppressors when they target oncogenes.

AREAS COVERED

In this review, areas covered include the role of miRNAs in cancer diagnosis, prognosis and research for achievement of therapeutic strategies implicating miRNAs in oncology. As biogenesis of miRNAs is fundamental to understand their usefulness, this has also been discussed. Both miRNA expression profiles in cancer tissues and miRNA levels in peripheral blood were studied for improvement in the management of cancer patients.

EXPERT OPINION

miRNAs have the potential for better understanding of tumor biology, but could also provide clinical advancement in management and therapy of various malignancies. The possibility of miRNA detection in peripheral blood would allow an eager expansion of their application in various clinical settings for cancer. The applicability of miRNA expression profiles still needs to be defined.