The relationship between and clinical significance of MicroRNA-32 and phosphatase and tensin homologue expression in colorectal cancer

FNIP1 suppresses colorectal cancer progression through inhibiting STAT3 phosphorylation and nuclear translocation

Folliculin interacting protein 1 (FNIP1) primarily participates in regulating cellular energy metabolism and is associated with Birt-Hogg-Dubé (BHD) syndrome. Although FNIP1 has been demonstrated to function as both a tumor suppressor and promoter, its role in colorectal cancer (CRC) remains unclear. Our study demonstrated a significant downregulation of FNIP1 in CRC, correlating with shorter overall and disease-specific survival. FNIP1 may potentially serve as an independent prognostic factor in CRC. Moreover, FNIP1 inhibited CRC progression in vitro and in vivo. Mechanistically, FNIP1 bound to phosphorylated signal transducer and activator of transcription-3 (p-STAT3) and downregulated its expression. FNIP1 deletion increased STAT3 phosphorylation and nuclear localization, thereby promoting CRC progression. The use of p-STAT3-specific chemical inhibitors successfully mitigated excessive tumorigenesis resulting from FNIP1 absence. Thus, our results suggest that FNIP1 hinders CRC progression by suppressing STAT3 phosphorylation and nuclear translocation. FNIP1 may be a candidate prognostic indicator and a therapeutic target for intervention in CRC.

Rs12039395 Variant Influences the Expression of hsa-miR-181a-5p and PTEN Toward Colorectal Cancer Risk

BACKGROUND

Single nucleotide polymorphisms (SNPs) in microRNA (miRNA) genes could alter miRNA expression levels or processing and, thus, may contribute to colorectal cancer (CRC) development. Therefore, this study aimed to examine whether the MIR181A1 genomic sequence possesses SNPs that can affect the expression of hsa-miR-181a-5p and, subsequently, impact its targets and associate with CRC risk.

METHODS

The NCBI dbSNP database was searched for possible SNPs associated with MIR181A1. One SNP with a minor allele frequency > 5%, rs12039395 G > T was identified. In silico analyses determined the effect of the SNP on the secondary structure of the miRNA and predicted the hsa-miR-181a-5p target genes. The SNP was genotyped using allelic discrimination assay, the relative hsa-miR-181a-5p expression level was determined using quantitative real-time PCR, and immunohistochemical staining was used to detect target genes in 192 paraffin-embedded specimens collected from 160 CRC patients and 32 healthy subjects.

RESULTS

The rs6505162 SNP conferred protection against CRC, and the G-allele presence provides may provide accessibility for the transcriptional machinery. Hsa-miR-181a-5p was significantly over-expressed in the CRC group compared to controls and in samples carrying the G-allele compared to those with T-allele. PTEN, identified as the only hsa-miR-181a-5p target implicated in CRC, was significantly diminished in the CRC group compared to controls and showed an inverse relationship with hsa-miR-181a-5p expression level as well as negatively associated with the G-allele presence in CRC.

CONCLUSION

This study highlights that rs12039395 G > T may protect against CRC by influencing the expression of hsa-mir-181a-5p and its target gene, PTEN.

Correlation of PTEN signaling pathway and miRNA in breast cancer

Breast cancer (BC) is one of the most common cancers among women and can be fatal if not diagnosed and treated on time. Various genetic and environmental factors play a significant role in the development and progression of BC. Within the body, different signaling pathways have been identified that contribute to cancer progression, or conversely, cancer prevention. Phosphatase and tensin homolog (PTEN) is one of the proteins that prevent cancer by inhibiting the oncogenic PI3K/Akt/mTOR signaling pathway. MicroRNAs (miRNAs) are molecules with about 18 to 28 base pairs, which regulate about 30% of human genes after transcription. miRNAs play a key role in the progression or prevention of cancer through different signaling pathway and mechanisms, e.g., apoptosis, angiogenesis, and proliferation. miRNAs, which are upstream mediators of PTEN, can reinforce or suppress the effect of PTEN signaling on BC cells, and suppressing the PTEN signaling, linked to weakness of the cancer cells to chemotherapeutic drugs. However, the precise mechanism and function of miRNAs on PTEN in BC are not yet fully understood. Therefore, in the present study, has been focused on miRNAs regulating PTEN function in BC.

miRNAs as cornerstones in colorectal cancer pathogenesis and resistance to therapy: A spotlight on signaling pathways interplay - A review

Colorectal cancer (CRC) is the world's third most prevalent cancer and the main cause of cancer-related mortality. A lot of work has been put into improving CRC patients' clinical care, including the development of more effective methods and wide biomarkers variety for prognostic, and diagnostic purposes. MicroRNAs (miRNAs) regulate a variety of cellular processes and play a significant role in the CRC progression and spread via controlling their target gene expression by translation inhibition or mRNA degradation. Consequently, dysregulation and disruption in their function, miRNAs are linked to CRC malignant pathogenesis by controlling several cellular processes involved in the CRC. These cellular processes include increased proliferative and invasive capacity, cell cycle aberration, evasion of apoptosis, enhanced EMT, promotion of angiogenesis and metastasis, and decreased sensitivity to major treatments. The miRNAs control cellular processes in CRC via regulation of pathways such as Wnt/β-catenin signaling, PTEN/AKT/mTOR axis, KRAS, TGFb signaling, VEGFR, EGFR, and P53. Hence, the goal of this review was to review miRNA biogenesis and present an updated summary of oncogenic and tumor suppressor (TS) miRNAs and their potential implication in CRC pathogenesis and responses to chemotherapy and radiotherapy. We also summarise the biological importance and clinical applications of miRNAs in the CRC.

Transcription factor forkhead box K1 regulates miR-32 expression and enhances cell proliferation in colorectal cancer

Increased microRNA (miR)-32 expression in colorectal cancer (CRC) tissues enhances CRC cell proliferation, migration, invasion and attenuates CRC cell apoptosis by repressing the expression of phosphatase and tensin homolog (PTEN). Forkhead box K1 (FOXK1) was identified as a potential interacting transcription factor using DNA pull-down assays and mass spectrometry. The present study aimed to elucidate the role of FOXK1 in regulating miR-32 expression in CRC. The expressions of FOXK1, miR-32, transmembrane protein 245 gene (TMEM245) and PTEN were compared between CRC and normal colonic tissues. Levels of miR-32, TMEM245, PTEN and the proliferation and apoptosis of CRC cells were studied using FOXK1-overexpression or knockdown, or by simultaneously interfering with FOXK1 and miR-32 expression. Direct FOXK1 binding to the miR-32 promoter was verified using chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays. The results showed elevated FOXK1, miR-32 and TMEM245 expression, and significantly decreased PTEN expression in CRC, compared with normal colonic tissues. Correlations between the expressions of TMEM245 and miR-32, FOXK1 and miR-32, and FOXK1 and TMEM245 were positive and significant. FOXK1-knockdown led to decreased miR-32 and TMEM245 expression and increased PTEN expression, whereas FOXK1-overexpression had the opposite effect. Overexpressed FOXK1 promoted the malignancy of CRC cells in vitro by stimulating proliferation and reducing apoptosis; whereas FOXK1-depletion suppressed such malignancy and a miR-32 inhibitor partially reversed the effects of FOXK1. The results of ChIP and dual-luciferase reporter assays indicated that FOXK1 directly binds to the promoter of TMEM245/miR-32. Thus, the FOXK1-miR-32-PTEN signaling axis may play a crucial role in the pathogenesis and development of CRC.

MicroRNAs that regulate PTEN as potential biomarkers in colorectal cancer: a systematic review

PURPOSE

MicroRNAs (miRNAs) participate in a variety of biological processes, including tumorigenesis, progression, invasion, and drug resistance to multiple cancers. Phosphatase and tensin homolog (PTEN) is a cancer suppressor gene that has been certified to be regulated by miRNAs in various tumors, including colorectal cancer (CRC). In this review, we screened articles focusing on low PTEN expression in CRC, observed the expression of related miRNAs, analyzed their correlation and relationship with clinicopathological features, and discussed the possibility of these miRNAs as prognostic molecules.

METHODS

We conducted a systematic search for articles published in the Web of Science, PubMed and EBSCO databases between January 1, 2002, and July 18, 2019. We identified these studies by using combinations of the following index entries and key words: 'colorectal tumor OR colorectal neoplasm OR colorectal carcinoma OR colorectal cancer OR CRC', 'protein tyrosine phosphatase OR PTEN', and 'microRNA OR MiRNA OR miRNA OR MicroRNA'. Moreover, we evaluated the underlying association between alterations in PTEN and CRC prognosis.

RESULTS

PTEN expression was obviously lower in CRC tissues than in normal mucosa. However, PTEN expression did not differ significantly between adenoma and normal tissues. PTEN tends to be negatively associated with tumor size and metastasis. MiR-21, miR-200a, miR-543, miR-32, miR-92a, miR-26a, miR-106a and miR-181a were correlated with the downregulation of PTEN. MiR-26a, miR-106a and miR-181a were obviously higher in CRC tissues than in normal tissues, while PTEN was downregulated in CRC tissues. Additionally, miRNAs were mainly positively correlated with distant metastasis, followed by TNM stage. The relationship between miRNAs and tumor differentiation is controversial. However, there were no significant differences between miRNAs and either sex or age.

CONCLUSIONS

The loss of PTEN may be a diagnostic factor for CRC patients. The above-mentioned miRNAs may function as oncogenes in CRC and represent potential targets for CRC therapy. However, further prospective clinical studies are necessary.

Role of Regulatory Oncogenic or Tumor Suppressor miRNAs of PI3K/AKT Signaling Axis in the Pathogenesis of Colorectal Cancer

Colorectal cancer (CRC) is the leading cause of cancer death worldwide and its incidence is increasing. In most patients with CRC, the PI3K/AKT signaling axis is over-activated. Regulatory oncogenic or tumor suppressor microRNAs (miRNAs) for PI3K/AKT signaling regulate cell proliferation, migration, invasion, angiogenesis, as well as resistance to chemo-/radio-therapy in colorectal cancer tumor tissues. Thus, regulatory miRNAs of PI3K/AKT/mTOR signaling represent novel biomarkers for new patient diagnosis and obtaining clinically invaluable information from post-treatment CRC patients for improving therapeutic strategies. This review summarizes the current knowledge of miRNAs' regulatory roles of PI3K/AKT signaling in CRC pathogenesis.

Enumeration of deregulated miRNAs in liquid and tissue biopsies of cervical cancer

OBJECTIVE

The altered miRNAs expression in cervical cancer tissue can be a critical player during tumorigenesis, may contribute to tumor cell heterogeneity and may determine distinct phenotypes within the tumor. Recent studies have highlighted the role of circulating miRNAs as a minimally-invasive biomarker and its potential as biosignature to complement routine tissue-based procedures.

METHODS

In order to determine whether miRNAs in serum can indicate changes in cervical tissue specimens, we performed small RNA sequencing and selected miRNAs were validated using qRT-PCR in serum and tissue specimens (n = 115). Further, luciferase assay were performed to investigate the interactions between hsa-miR-409-3p and hsa-miR-454-3p binding sites on 3'UTR region of MTF2 and ST18 respectively.

RESULTS

We have identified a total of 14 differentially expressed miRNAs common in serum and tissue specimens. Among them, hsa-miR-17-5p, hsa-miR-32-5p and hsa-miR-454-3p were upregulated while, hsa-miR-409-3p was downregulated in serum and tissue of cervical cancer subjects. Our in-silico small RNA sequencing data analysis identified isomiRs and classified miRNA into clusters and subtypes (exonic, intronic and intergenic) with respect to the expression status in serum and tissue specimens. Expression level of hsa-miR-409-3p and hsa-miR-454-3p were inversely correlated with their target genes MTF2 and ST18 levels respectively in human cervical cancer specimens. Luciferase assay demonstrated that hsa-miR-409-3p and hsa-miR-454-3p functionally interacts with 3'-UTR of MTF2 and ST18 respectively to decrease their activity.

CONCLUSION

Our results support the significant role of circulating miRNAs in disease dissemination and their potential utility as biosignatures of clinical relevance.

Analysis of promoter methylation and epigenetic regulation of miR-32 in colorectal cancer cells

MicroRNA-32 (miR-32) is upregulated in colorectal cancer (CRC) tissues; its overexpression leads to increased cell proliferation, migration and invasion, as well as reduced apoptosis of CRC cells, at least partly by inhibiting the target gene phosphatase and tensin homolog. However, the mechanisms of its upregulation have remained elusive. In the present study, the effects of methylation and acetylation on the expression of miR-32 were investigated. The promoter methylation status of miR-32 in the CRC cell lines HT-29 and HCT-116 and the normal colonic epithelial cell line NCM460 was investigated by bisulfate sequencing polymerase chain reaction (BSP). The potential role of methylation and histone acetylation in the regulation of miR-32 expression in CRC cells was investigated using the demethylation reagent 5-aza-2'-deoxycytidine (5-Aza-dC), the histone deacetylase inhibitor trichostatin A (TSA) and transfection of DNA methyltransferase 1 (DNMT1) overexpression plasmid. BSP revealed that CpG sites in the miR-32 promoter region of CRC and normal colonic epithelial cells were all hypomethylated, with methylation rates of 0.12, 1.14 and 0.64% in HCT-116, HT-29 and NCM460 cells, respectively. Treatment with 5-Aza-dC and/or TSA and transfection with DNMT1 plasmid did not significantly alter the expression of miR-32. Therefore, the present results suggest that methylation and histone acetylation do not affect miR-32 expression in CRC cells.

Analysis of the promoter region of the human miR-32 gene in colorectal cancer

The pathogenesis of colorectal cancer (CRC) is poorly understood. MicroRNA (miR)-32 upregulation in CRC tissues was previously reported, where it increased the proliferation, migration and invasion, and reduced apoptosis of CRC cells by inhibiting the expression of phosphatase and tensin homolog (PTEN). However, the mechanism underlying miR-32 upregulation remains unknown. miR-32 is an intronic miRNA located within intron 14 of the transmembrane protein 245 gene (TMEM245). The present study aimed to elucidate the biological pathways underlying miR-32 regulation in CRC. A truncated promoter containing the 5′-flanking region of TMEM245/miR-32 gene was constructed. The promoter region was analyzed by dual luciferase reporter assay in CRC cells. DNA pull-down assay and mass spectrometry (MS) were used to identify proteins binding to the core promoter. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and transcription factor (TF) analyses were used to identify the binding proteins. The −320 to −1 bp fragment of the 5′-flanking region exhibited the highest luciferase activity. The regions spanning −606 to −320 bp exhibited a significant decrease in luciferase activity, compared with the −320 to −1 bp fragment. DNA pull-down assay and MS revealed 403 potential miR-32 promoter binding proteins. GO and KEGG pathway analysis indicated that these proteins were involved in numerous physiological and biochemical processes, including ‘structural molecule activity’, ‘RNA binding’, ‘small molecule metabolic process’ and ‘biogenesis’. Furthermore, TF analysis revealed 10 potential interacting TFs, including SMAD family member 1 (SMAD1), signal transducer and activator of transcription 1 (STAT1) and forkhead box K1 (Foxk1). These results suggested that the core promoter region may be located within-320 to −1 bp of the 5′-flanking region of TMEM245/miR-32 gene, while the region from −606 to −320 bp may harbor repressive regulatory elements. The TFs SMAD1, STAT1 and Foxk1 may be involved in the transcriptional regulation of miR-32.

Prognostic value of microRNAs in colorectal cancer: a meta-analysis

Background

Numerous studies have shown that miRNA levels are closely related to the survival time of patients with colon, rectal, or colorectal cancer (CRC). However, the outcomes of different investigations have been inconsistent. Accordingly, a meta-analysis was conducted to study associations among the three types of cancers.

Materials and methods

Studies published in English that estimated the expression levels of miRNAs with survival curves in CRC were identified until May 20, 2017 by online searches in PubMed, Embase, Web of Science, and the Cochrane Library by two independent authors. Pooled HRs with 95% CIs were used to estimate the correlation between miRNA expression and overall survival.

Results

A total of 63 relevant articles regarding 13 different miRNAs, with 10,254 patients were ultimately included. CRC patients with high expression of blood miR141 (HR 2.52, 95% CI 1.68-3.77), tissue miR21 (HR 1.31, 95% CI 1.12-1.53), miR181a (HR 1.52, 95% CI 1.26-1.83), or miR224 (HR 2.12, 95% CI 1.04-4.34), or low expression of tissue miR126 (HR 1.55, 95% CI 1.24-1.93) had significantly poor overall survival (P<0.05).

Conclusion

In general, blood miR141 and tissue miR21, miR181a, miR224, and miR126 had significant prognostic value. Among these, blood miR141 and tissue miR224 were strong biomarkers of prognosis for CRC.

Exosomal microRNA-32-5p induces multidrug resistance in hepatocellular carcinoma via the PI3K/Akt pathway

BACKGROUND

Multidrug resistance is the main obstacle for hepatocellular carcinoma (HCC) treatment. miR-32-5p is involved in HCC progression but its function in multidrug resistance is still unclear. Here we aim to find out the function of miR-32-5p in inducing multidrug resistance and its underlying mechanisms of transforming sensitive cell to resistant cell.

METHODS

We detected the expression of miR-32-5p and PTEN in the multidrug-resistant cell line (Bel/5-FU) and the sensitive cell line (Bel7402), HCC and para-carcinoma liver tissues through real-time PCR. Dual-luciferase reporter assay verified PTEN is the target of miR-32-5p. Exosomes from sensitive and multidrug resistant cell line were obtained and confirmed through ultracentrifuge and Nano Analyzer. Gain- and loss-of-function experiments, rescue experiments, a PI3K/Akt pathway inhibitor, an exosome biogenesis inhibitor, and nude mice xenograft models were used to determine the underlying mechanisms of miR-32-5p and PTEN, as well as exosomal miR-32-5p in inducing multidrug resistance in vitro and in vivo.

RESULTS

miR-32-5p was significantly elevated but PTEN was reduced in Bel/5-FU. An inverse correlation between miR-32-5p and PTEN was confirmed in HCC cell lines and patients; moreover, high expression of miR-32-5p and low expression of PTEN were positively associated with poor prognosis. Over-expression of miR-32-5p activated the PI3K/Akt pathway by suppressing PTEN and induced multidrug resistance via exosomes through promoting angiogenesis and epithelial-mesenchymal transition (EMT).

CONCLUSIONS

Our study demonstrated that the multidrug-resistant cell, Bel/5-FU delivers miR-32-5p to sensitive cell, Bel7402 by exosomes and activates the PI3K/Akt pathway to further induce multidrug resistance by modulating angiogenesis and EMT.

Upregulation of microRNA-32 is associated with tumorigenesis and poor prognosis in patients with hepatocellular carcinoma

MicroRNA-32 (miR-32) is associated with tumor progression and poor prognosis in certain malignant tumors. However, the function and clinical relevance of miR-32 in human hepatocellular carcinoma (HCC) has not yet been elucidated. The present study aimed to investigate the expression and prognostic value of miR-32 from liver samples in patients with HCC. The expression of miR-32 was analyzed in HCC and healthy tissues using Gene Expression Omnibus datasets. Reverse transcription-quantitative polymerase chain reaction was used to analyze the levels of miR-32 mRNA in 154 HCC liver samples, 33 of which were paired with adjacent non-tumor tissues. The overall survival (OS) rate in patients with HCC was evaluated using Kaplan-Meier survival analysis, and the factors that may affect the prognosis and survival of patients with HCC were analyzed using univariate (log-rank test) and multivariate Cox proportional hazard models. The present results demonstrated that miR-32 expression levels were significantly upregulated in HCC liver biopsies compared with normal tissues (P<0.05). miR-32 expression was significantly associated with the number of foci and tumor diameter (P<0.05). In addition, Kaplan-Meier analysis revealed that patients with low miR-32 expression had longer OS and disease-free survival compared with those with high miR-32 expression (P<0.01). Altogether, to the best our knowledge, the present study is the first study to indicate the association between increased miR-32 expression with HCC progression and poor prognosis in patients. This suggests that miR-32 may have potential prognostic value and may be used as a tumor biomarker for the diagnosis of patients with HCC.

Down-regulation of miRNA-30c predicts poor prognosis in Colorectal Cancer patients

Background: MiRNA-30c was a tumor suppressor in several human cancers, however, its association with clinicopathological features and prognosis in colorectal cancer (CRC) is unclear.

Materials and Methods: The expression level of miRNA-30c in 192 pairs of colorectal cancer and adjacent normal tissues was detected by Quantitative RT-PCR, the association between miRNA-30c expression and clinical characteristics and prognosis were statistically analyzed.

Results: miRNA-30c was significantly lower in CRC tissues specimens compared with matched normal adjacent tissue (P<0.001). MiRNA-30c was positively correlated with tumor size (P=0.012), TMN stage (P=0.002) and lymph node metastasis (P=0.004). The univariate analysis showed CRC patients with low miRNA-30c had distinctly shorter overall survival (P<0.001) than patients with high miRNA-30c expression level. The multivariate analysis was performed and informed that low miRNA-30c expression (P<0.001) might be an independent prognostic predictor for poor prognosis.

Conclusion: miRNA-30c could predict the prognosis of colorectal cancer which is helpful to choose reasonable treatment measures.

MicroRNA-20b (miR-20b) Promotes the Proliferation, Migration, Invasion, and Tumorigenicity in Esophageal Cancer Cells via the Regulation of Phosphatase and Tensin Homologue Expression

Increasing evidence has indicated that many microRNAs participate in the development and progression of esophageal cancer and gene expression regulation. MicroRNA-20b (miR-20b) has been reported to be aberrantly expressed in various cancers, but its exact role in esophageal cancer cells remains unclear so far. Therefore, we detected the levels of miR-20b in esophageal tumor tissues and their adjacent normal tissues, and various esophageal cancer cell lines by qRT-PCR. We also explored the effects of miR-20b on cell proliferation, migration, invasion and tumorigenicity of esophageal carcinoma cells through transfection with miR-20b mimics or inhibitor to upregulate or downregulate miR-20b expression in the esophageal cancer cells Eca-109 and KYSE-150, respectively. Additionally, the 3'-untranslated region (3'-UTR) of phosphatase and tensin homologue (PTEN) binding with miR-20b was analyzed by dual-luciferase reporter assays. The results indicated that miR-20b expression level in esophageal tumor tissues was significantly increased compared with their neighboring normal tissues, but its expression was inverse with PTEN protein expression. Luciferase assays confirmed that the 3'-UTR of PTEN was a target of miR-20b in esophageal cancer cells. MiR-20b upregulation promoted cell proliferation, migration, invasiveness, and tumor growth, and decreased apoptosis, and reduced PTEN protein level but not mRNA expression in Eca-109 cells. Conversely, downregulation of miR-20b suppressed these processes in KYSE-150 cells, and enhanced PTEN protein expression. These data indicate that miR-20b plays important roles in tumorigenesis of esophageal cancer possibly via regulation of PTEN expression, and it may be a potential therapeutic target for esophageal cancer treatment.

In Silico Study of miRNA Based Gene Regulation, Involved in Solid Cancer, by the Assistance of Argonaute Protein

Solid tumor is generally observed in tissues of epithelial or endothelial cells of lung, breast, prostate, pancreases, colorectal, stomach, and bladder, where several genes transcription is regulated by the microRNAs (miRNAs). Argonaute (AGO) protein is a family of protein which assists in miRNAs to bind with mRNAs of the target genes. Hence, study of the binding mechanism between AGO protein and miRNAs, and also with miRNAs-mRNAs duplex is crucial for understanding the RNA silencing mechanism. In the current work, 64 genes and 23 miRNAs have been selected from literatures, whose deregulation is well established in seven types of solid cancer like lung, breast, prostate, pancreases, colorectal, stomach, and bladder cancer. In silico study reveals, miRNAs namely, miR-106a, miR-21, and miR-29b-2 have a strong binding affinity towards PTEN, TGFBR2, and VEGFA genes, respectively, suggested as important factors in RNA silencing mechanism. Furthermore, interaction between AGO protein (PDB ID-3F73, chain A) with selected miRNAs and with miRNAs-mRNAs duplex were studied computationally to understand their binding at molecular level. The residual interaction and hydrogen bonding are inspected in Discovery Studio 3.5 suites. The current investigation throws light on understanding miRNAs based gene silencing mechanism in solid cancer.

MiR-32 contributed to cell proliferation of human breast cancer cells by suppressing of PHLPP2 expression

MicroRNAs (miRNAs) have been identified as important regulators that potentially play critical roles in various biological and pathological processes of cancer cells. The aim of the present study was to investigate the expression of miR-32 in breast cancer and its biological role in tumor progression. MiR-32 expression was markedly upregulated in breast cancer tissues and breast cancer cells. Ectopic expression of miR-32 promoted cell proliferation of breast cancer, whereas miR-32-in suppressed this function. Mechanically, data from luciferase reporter assays revealed that miR-32 directly targeted to the 3'-untranslated region (3'-UTR) of PHLPP2. Overexpression of miR-32 led to downregulation of PHLPP2 protein, which resulted in the downregulation of p21 and upregulation of cyclin D1 and p-Rb. In functional assays, PHLPP2-silenced in miR-32-in-transfected ZR-75-30 cells have positive effect to promote cell proliferation, suggesting that direct PHLPP2 downregulation is required for miR-32-induced cell proliferation of breast cancer. Our findings highlighted the importance of miR-32 in promoting tumor progression, and implicate miR-32 as a potential therapeutic target in breast cancer.

Expression and clinical significance of microRNA-376a in colorectal cancer

The incidence of colorectal cancer (CRC) is increasing in many Asian countries and microRNAs have already been proven to be associated with tumorigenesis. Currently, microRNA-376a (miR-376a) expression and association with clinical factors in CRC remains unclear. In this study, real-time quantitative reverse transcriptase- polymerase chain reaction (qRT-PCR) was carried out on 53 matched pairs of CRC and adjacent normal mucosa to investigate the expression levels of miR-376a. According to the high or low expression of miR-376a, patients were divided into two groups. The relationship between miR-376a expression and clinicopathological factors of 53 patients was evaluated. Survival analysis of 53 CRC patients was performed with clinical follow- up information and survival curves were assessed by the Kaplan-Meier method. Immunohistochemistry (IHC) staining was performed on sections of paraffin-embedded tissue to investigate the vascular endothelial growth factor (VEGF) expression. MiR-376a showed low expression in cancer tissues compared to the adjacent normal tissues and altered high miR-376a expression tended to be positively correlated with advanced lymph node metastasis and shorter patient survival. VEGF IHC positivity was significantly more common in patients with high expression levels of miR-376a.Those results demonstrated that miR-376a may be a meaningful prognostic biomarker and potential therapeutic target in colorectal cancer.

MicroRNAs potential utility in colon cancer: Early detection, prognosis, and chemosensitivity

Over the past decade, research has shown that aberrant expression of microRNA (miRNA) is involved in colorectal cancer development and progression. MicroRNAs are small sequences of non-coding RNA that regulate expression of genes involved in important cellular functions, such as cell differentiation, multiplication, and apoptosis. A specific miRNA may display the effects of a tumor suppressor or oncogene. Altered miRNA expression is found in colorectal cancer (CRC) and patterns of miRNA expression correlate with CRC detection and outcome. Studies also have examined the use of circulating serum miRNA and fecal miRNA expression as non-invasive markers for early detection. Here, we review recent evidence demonstrating the potential role of miRNA in CRC and the implications of its use in the diagnosis, prognosis, and management of CRC.

miR-32 functions as a tumor suppressor and directly targets SOX9 in human non-small cell lung cancer

Purpose

MicroRNA-32 (miR-32) is dysregulated in certain human malignancies and correlates with tumor progression. However, its expression and function in non-small cell lung cancer (NSCLC) remain unclear. Thus, the aim of this study was to explore the effects of miR-32 expression on NSCLC tumorigenesis and development.

Methods

Using real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR), we detected miR-32 expression in NSCLC cell lines and primary tumor tissues. The association of miR-32 expression with clinicopathological factors and prognosis was also analyzed. Then, the effects of miR-32 expression on the biological behavior of NSCLC cells were investigated. Finally, the potential regulatory effect of miR-32 on SOX9 expression was confirmed.

Results

miR-32 expression levels were significantly downregulated in NSCLC compared with the corresponding noncancerous lung tissues (P<0.001). In addition, decreased miR-32 expression was significantly associated with lymph node metastasis (P=0.002), advanced tumor/nodes/metastasis (TNM) classification stages (P<0.001), and shorter overall survival (P<0.001). Multivariate regression analysis corroborated that downregulated miR-32 expression was an independent unfavorable prognostic factor for NSCLC patients. In vitro studies demonstrated that miR-32 overexpression reduced A549 cell proliferation, migration, and invasion, and promoted apoptosis. Furthermore, SOX9 was confirmed as a direct target of miR-32, using a luciferase reporter assay.

Conclusion

These findings indicate that miR-32 may act as a tumor suppressor in NSCLC and could serve as a novel therapeutic agent for miR-based therapy.

MiR-32 induces cell proliferation, migration, and invasion in hepatocellular carcinoma by targeting PTEN

MicroRNAs (miRNAs) regulate gene expression by inhibiting translation of target messenger RNAs (mRNAs) through pairing with miRNA recognition elements (MREs), usually in 3'-UTRs. miRNAs are involved in the pathogenesis of several types of cancers. Specifically, microRNA-32 (miR-32) is overexpressed in colorectal carcinoma, wherein accumulating evidence indicates that it functions as an oncogene. However, the function of miR-32 in hepatocellular carcinoma (HCC) has not been totally elucidated. In the present study, we found the expression of miR-32 was up-regulated in HCC tissue and cell lines, inversely the expression of phosphatase and tensin homolog (PTEN) decreased. Besides, miRNA-32 down-regulates PTEN through binding to 3'-UTR of PTEN mRNA from luciferase reporter assay, and the expression level of miR-32 could affect the proliferation, migration, and invasion of liver cancer cell lines via PTEN/Akt signaling pathway. Down-expression of PTEN could significantly attenuate the inhibitory effects of knockdown miR-32 on the proliferation, migration, and invasion of liver cancer cells, suggesting that miR-32 could be a potential target for HCC treatment.

miRNA expression in human intestinal Caco-2 cells is comparably regulated by cis- and trans-fatty acids

Trans-fatty acids are unsaturated fatty acids with at least one double bond in trans configuration. While their role in the development of coronary heart disease is broadly accepted, a potential impact of these fatty acids on colon carcinogenesis is still under discussion. MiRNAs are small non-coding RNAs that regulate the gene expression at a post-transcriptional level by inhibiting the translation of target mRNAs. We investigated the effect of 16 different C 18 fatty acid isomers on the expression of 84 cancer-related miRNAs in the human colorectal adenocarcinoma cell line Caco-2 by using a qRT-PCR array. 66 of these 84 miRNAs were deregulated by at least one fatty acid, however, there was no trans-specific impact on miRNA expression as the corresponding cis isomer of a given fatty acid generally had comparable effects on the miRNA expression profile. The most pronounced effects were observed for hsa-miR-146a-5p, which was upregulated by four of the 16 investigated fatty acids, and hsa-miR-32-5p, which was strongly downregulated by five fatty acids. As hsa-miR-32-5p was described to target genes being involved in the regulation of apoptosis, the effect of α-eleostearic acid on the expression of the apoptosis-associated genes BCL2L11, BCL-2, and BCL-XL was examined. The qPCR results indicate that fatty acid-mediated downregulation of hsa-miR-32-5p is accompanied by a downregulation of BCL-2 and BCL2L11 mRNA whereas BCL-XL was shown to be simultaneously upregulated. In conclusion, our data indicate that several fatty acids are able to regulate miRNA expression of human colon cancer cells. However, no trans-specific regulation was observed.

MiR-32 functions as a tumor suppressor and directly targets EZH2 in human oral squamous cell carcinoma

Background

MicroRNA-32 (miR-32) is dysregulated in certain human malignancies and correlates with tumor progression. However, its expression and function in oral squamous cell carcinoma (OSCC) remain unclear. Thus, the aim of this study was to explore the effects of miR-32 expression on OSCC tumorigenesis and development.

Material/Methods

Real-time quantitative PCR was applied to evaluate the expression level of miR-32 in OSCC cell lines and primary tumor tissues. The association of miR-32 expression with clinicopathological factors and prognosis was also analyzed. In vitro cell proliferation, apoptosis, invasion, and migration assays were executed to elucidate biological effects of miR-32. Western blotting and luciferase assays were performed to confirm the regulation of EZH2 by miR-32.

Results

Down-regulation of miR-32 was found in OSCC tissues compared with corresponding noncancerous tissues (P<0.001). Decreased miR-32 expression was significantly associated with advanced T classifications, positive N classification, advanced TNM stage, and shorter overall survival (all P<0.05). Multivariate regression analysis corroborated that low-level expression of miR-32 was an independent unfavorable prognostic factor for OSCC patients. In vitro functional assays showed that overexpression of miR-32 reduced OSCC cell proliferation, migration, and invasion, and promoted cell apoptosis. In contrast, miR-32 knock-down resulted in an increase in cell growth and invasiveness. Finally, we identified EZH2 as the functional downstream target of miR-32 by directly targeting the 3′-UTR of EZH2.

Conclusions

These findings indicate that miR-32 may act as a tumor suppressor in OSCC and could serve as a novel therapeutic agent for miR-based therapy.

An update on microRNAs as colorectal cancer biomarkers: where are we and what's next?

miRNAs are abundant classes of small, endogenous non-coding RNAs, which inhibit the expression of target gene via post-transcriptional regulation. In addition to an important functional role miRNAs play in carcinogenesis, emerging evidence has demonstrated their feasibility as robust cancer biomarkers. In particular, the recent discovery of miRNAs in the body fluids provides an attractive opportunity for the development of non-invasive biomarkers for the diagnosis, prognosis and predictive response to cancer therapy. Colorectal cancer (CRC) is one of the most common cancers worldwide, and accumulating data provides a compelling case for the potential exploitation of miRNAs as CRC-biomarkers. This review summarizes the current state of literature in the field, focusing on the clinical relevance of miRNAs as potential biomarkers for CRC treatment and discussing the forthcoming challenges to further advance this exciting field of 'academic research' into 'bedside clinical care' of patients suffering from CRC.

MicroRNA expression patterns of tumors in early-onset colorectal cancer patients

BACKGROUND

The expression of microRNAs (miRNAs) may differ in tumors from patients with different ethnic origins and ages. The aims of the present study were to clarify the appropriate alterations of miRNA expression associated with the early stages of carcinogenesis in early-onset Turkish colorectal cancer (CRC) patients and to define specific biomarkers that could be used as new diagnostic and prognostic markers for this population.

MATERIALS AND METHODS

The expression profiles of 38 different miRNAs associated with CRC were evaluated using miRNA polymerase chain reaction arrays in tumors and surgical margin tissue samples from 40 sporadic early-onset Turkish CRC patients. The relationships between the miRNA expression profiles and the characteristics of the tumors and patients were evaluated.

RESULTS

The expression of miR-106a was found to be upregulated, and miR-143 and miR-125b levels were found to be downregulated in tumor tissues compared with the normal tissues. The high expression level of miR-106a (2.93-fold; P = 0.031) and low expression level of miR-125b (2.42-fold; P = 0.063) were observed in tumors with lymph node metastases compared with the normal colorectal mucosa samples. However, the deregulation of these miRNAs was not significantly associated with survival (log-rank P > 0.05).

CONCLUSIONS

The present results implied that miR-106a and the miR-125b were associated with the formation and invasion of colorectal tumors. Thus, these miRNAs might be used as significant prognostic factors and indicators of early-stage CRC. Further studies and validations are required; these miRNAs may provide novel molecular targets for CRC treatment.