Exosomal microRNA-21-5p Mediates Mesenchymal Stem Cell Paracrine Effects on Human Cardiac Tissue Contractility

RATIONALE

The promising clinical benefits of delivering human mesenchymal stem cells (hMSCs) for treating heart disease warrant a better understanding of underlying mechanisms of action. hMSC exosomes increase myocardial contractility; however, the exosomal cargo responsible for these effects remains unresolved.

OBJECTIVE

This study aims to identify lead cardioactive hMSC exosomal microRNAs to provide a mechanistic basis for optimizing future stem cell-based cardiotherapies.

METHODS AND RESULTS

Integrating systems biology and human engineered cardiac tissue (hECT) technologies, partial least squares regression analysis of exosomal microRNA profiling data predicted microRNA-21-5p (miR-21-5p) levels positively correlate with contractile force and calcium handling gene expression responses in hECTs treated with conditioned media from multiple cell types. Furthermore, miR-21-5p levels were significantly elevated in hECTs treated with the exosome-enriched fraction of the hMSC secretome (hMSC-exo) versus untreated controls. This motivated experimentally testing the human-specific role of miR-21-5p in hMSC-exo-mediated increases of cardiac tissue contractility. Treating hECTs with miR-21-5p alone was sufficient to recapitulate effects observed with hMSC-exo on hECT developed force and expression of associated calcium handling genes (eg, SERCA2a and L-type calcium channel). Conversely, knockdown of miR-21-5p in hMSCs significantly diminished exosomal procontractile and associated calcium handling gene expression effects on hECTs. Western blots supported miR-21-5p effects on calcium handling gene expression at the protein level, corresponding to significantly increased calcium transient amplitude and decreased decay time constant in comparison to miR-scramble control. Mechanistically, cotreating with miR-21-5p and LY294002, a PI3K inhibitor, suppressed these effects. Finally, mathematical simulations predicted the translational capacity for miR-21-5p treatment to restore calcium handling in mature ischemic adult human cardiomyocytes.

CONCLUSIONS

miR-21-5p plays a key role in hMSC-exo-mediated effects on cardiac contractility and calcium handling, likely via PI3K signaling. These findings may open new avenues of research to harness the role of miR-21-5p in optimizing future stem cell-based cardiotherapies.

MicroRNA-155 promotes gastric cancer growth and invasion by negatively regulating transforming growth factor-β receptor 2

Gastric cancer (GC) is one of the most common malignancies worldwide and has high morbidity and mortality rates. It is essential to elucidate the molecular events of GC proliferation and invasion, which will provide new therapeutic targets for GC. The inactivation of transforming growth factor-β receptor 2 (TGFβR2) correlates with cancer cell growth and metastasis, but the mechanisms underlying the downregulation of TGFβR2 expression remain unknown. MicroRNAs (miRNAs) act as post-transcriptional regulators and play a key role in the development of cancers. Bioinformatics analysis and luciferase reporter assays have shown that miR-155 directly binds to the 3'-UTR of TGFβR2 mRNA. In this study, we found that the TGFβR2 protein levels, but not mRNA levels, were downregulated in GC tissues, and the levels of miR-155 were significantly increased in GC tissues. We deduced that miR-155 was inversely correlated with TGFβR2 in GC cells. In vitro studies showed that overexpression of miR-155 in SGC7901 inhibited the expression of TGFβR2 and then promoted GC cell proliferation and migration, whereas miR-155 inhibitor showed opposite effects. In addition, the tumor-suppressing function of TGFβR2 was verified by using siRNA and TGFβR2 overexpressing plasmids. The results showed that miR-155 promotes cell growth and migration by negatively regulating TGFβR2. Thus, miR-155-regulated TGFβR2 as a potential therapeutic target in GC.

miR-33a-5p enhances the sensitivity of lung adenocarcinoma cells to celastrol by regulating mTOR signaling

MicroRNAs (miRNAs or miRs) have recently become a popular focus of cancer research due to their ability to act as oncogenes or tumor suppressors. In the present study, miR‑33a‑5p expression was identified to be downregulated in lung adenocarcinoma samples compared with normal, which suggested that miR‑33a‑5p may serve as a tumor suppressor gene. Transfection with miR‑33a‑5p mimics inhibited the proliferation and migration of A549 and LTEP‑a‑2 cells and increased cellular apoptosis. A luciferase reporter assay confirmed that miR‑33a‑5p targets the 3'‑untranslated region of the mechanistic target of rapamycin (mTOR) gene. mTOR expression was decreased in A549 and LTEP‑a‑2 cells treated with miR‑33a‑5p mimics, as well as the expression of its downstream effectors phosphorylated (p)‑p70 ribosomal protein S6 kinase (p70S6K) and p‑eukaryotic translation initiation factor 4E binding protein 1 (4EBP1). Following treatment with celastrol, miR‑33a‑5p expression was upregulated, and miR‑33a‑5p could enhance cellular sensitivity to celastrol. Western blot analysis revealed that the expression of mTOR, p‑p70S6K and p‑4EBP1 decreased following celastrol treatment. These results suggested that mTOR was involved in the mechanism by which miR‑33a‑5p enhanced the sensitivity of lung adenocarcinoma cells to celastrol. Furthermore, LTEP‑a‑2 cells were xenografted subcutaneously into nude mice, to examine the effect of celastrol and miR‑33a‑5p on the growth of LTEP‑a‑2 cells in vivo. The results demonstrated that tumor growth in the celastrol‑treated or miR‑33a‑5p‑treated group was attenuated compared with the control group. Notably, tumor growth in the combination treatment group was almost arrested after 2 weeks. In addition, celastrol upregulated the expression of miR‑33a‑5p, and high expression of miR‑33a‑5p inhibited mTOR and its downstream effectors. In summary, miR‑33a‑5p inhibited the proliferation of lung adenocarcinoma cells, enhanced the antitumor effect of celastrol, and improved sensitivity to celastrol by targeting mTOR in lung adenocarcinoma in vitro and in vivo.

MicroRNA-1253 suppresses cell proliferation and invasion of non-small-cell lung carcinoma by targeting WNT5A

MicroRNAs (miRNA) are a class of small, noncoding RNA molecules that regulate the expression of target genes. miRNA dysregulation is involved in carcinogenesis and tumor progression. In this study, we identified microRNA-1253 (miR-1253) as being significantly down-regulated in non-small-cell lung carcinoma (NSCLC) tissues and associated with advanced clinical stage, lymph node metastasis, and poor survival. The enhanced expression of miR-1253 significantly inhibited the proliferation, migration, and invasion of NSCLC cells in vitro. Bioinformatics analyses showed that miR-1253 directly targeted WNT5A (long isoform), which was confirmed using the dual-luciferase reporter assay. The inhibitory effects of miR-1253 on the growth and metastasis of NSCLC cells were attenuated and phenocopied by WNT5A (long) overexpression and knockdown, respectively. Consistent with the in vitro results, subcutaneous tumor and metastatic NSCLC mouse models showed that miR-1253 functions as a potent suppressor of NSCLC in vivo. Taken together, our findings indicated that miR-1253 inhibited the proliferation and metastasis of NSCLC cells by targeting WNT5A (long isoform) and provided new evidence of miR-1253 as a potential therapeutic target in NSCLC.

MiR-96 enhances cellular proliferation and tumorigenicity of human cervical carcinoma cells through PTPN9

Up to date, the cervical cancer remains to be one of the leading gynecological malignancies worldwide. MicroRNAs (miRNAs) play critical roles in the process of tumor initiation and progression. However, miR-96 has rarely been investigated in human cervical carcinoma. We aimed to investigate the biological function and underlying molecular mechanism of miR-96 in human cervical carcinoma. MiR-96 levels were determined by qRT-PCR. Protein tyrosine phosphatase, non-receptor type 9 (PTPN9) mRNA and protein levels were investigated by qRT-PCR and western blotting. The cellular proliferation in cervical cells was monitored by CyQuant assay. Soft agar assay was employed to determine the tumorigenicity. 3' UTR luciferase assay was used to validate the target gene of miR-96. SPSS was used to analyze statistical significance in different treatment. MiR-96 was dramatically upregulated in human cervical tumor tissues. Overexpression of miR-96 was found to significantly promote the cellular proliferation and tumorigenicity of cervical cells. Furthermore, we showed that PTPN9 was a direct target gene of miR-96 and had opposite effect to those of miR-96 on cervical cells. MiR-96 may promote the cellular proliferation and tumorigenicity of cervical cells by silencing PTPN9. Our study highlights an importantly regulatory role of miR-96 and suggests that an appropriate manipulation of miR-96 may be a new treatment of human cervical carcinoma in the future.

miR-143-3p targeting of ITGA6 suppresses tumour growth and angiogenesis by downregulating PLGF expression via the PI3K/AKT pathway in gallbladder carcinoma

Gallbladder cancer (GBC) is the most common malignant tumour of the biliary track system. Angiogenesis plays a pivotal role in the development and progression of malignant tumours. miR-143-3p acts as a tumour suppressor in various cancers. Their role in GBC is however less well defined. Here we show that the expression levels of miR-143-3p were decreased in human GBC tissues compared with the non-tumour adjacent tissue (NAT) counterparts and were closely associated with overall survival. We discovered that miR-143-3p was a novel inhibitor of tumour growth and angiogenesis in vivo and in vitro. Our antibody array, ELISA and PLGF rescue analyses indicated that PLGF played an essential role in the antiangiogenic effect of miR-143-3p. Furthermore, we used miRNA target-prediction software and dual-luciferase assays to confirm that integrin α6 (ITGA6) acted as a direct target of miR-143-3p. Our ELISA and western blot analyses confirmed that the expression of PLGF was decreased via the ITGA6/PI3K/AKT pathway. In conclusion, miR-143-3p suppresses tumour angiogenesis and growth of GBC through the ITGA6/PI3K/AKT/PLGF pathways and may be a novel molecular therapeutic target for GBC.

Prognostic role of elevated mir-24-3p in breast cancer and its association with the metastatic process

MicroRNAs have been shown to play important roles in breast cancer progression and can serve as biomarkers. To assess the prognostic role of a panel of miRNAs in breast cancer, we collected plasma prospectively at the time of initial diagnosis from 1,780 patients with stage I-III breast cancer prior to definitive treatment. We identified plasma from 115 patients who subsequently developed distant metastases and 115 patients without metastatic disease. Both groups were matched by: age at blood collection, year of blood collection, breast cancer subtype, and stage. The median follow up was 3.4 years (range, 1-9 years). We extracted RNA from plasma and analyzed the expression of 800 miRNAs using Nanostring technology. We then assessed the expression of miRNAs in primary and metastatic breast cancer samples from The Cancer Genome Atlas (TCGA). We found that, miR-24-3p was upregulated in patients with metastases, both in plasma and in breast cancer tissues. Patients whose primary tumors expressed high levels of miR-24-3p had a significantly lower survival rate compared to patients with low mir-24-3p levels in the TCGA cohort (n=1,024). RNA-Seq data of the samples with the highest miR-24-3p expression versus those with the lowest miR-24-3p in the TCGA cohort identified a specific gene expression signature for those tumors with high miR-24-3p. Possible target genes for miR-24-3p were predicted based on gene expression and binding site, and their effects on cancer pathways were evaluated. Cancer, breast cancer and proteoglycans were the top three pathways affected by miR-24-3p overexpression.

Increased circular RNA hsa_circ_0012673 acts as a sponge of miR-22 to promote lung adenocarcinoma proliferation

Recent reports have indicated that circular RNA (circRNA) may regulate Lung adenocarcinoma (LAC) development. Our previous studies showed that hsa_circ_0012673 was up-regulated in a circRNA microarray. However, its expression level in LAC has not been verified, and the underlying molecular mechanisms in LAC are unknown. In this study, we found that the expression of hsa_circ_0012673 was up-regulated in LAC tissues compared to pair-matched adjacent non-tumor tissues (P = 0.0079), and that the expression level was associated with tumour size (P = 0.015). Furthermore, hsa_circ_0012673 was primarily localized in the cytoplasm and promoted cell proliferation of LAC cells by sponging miR-22, which targeted erb-b2 receptor tyrosine kinase 3 (ErbB3) in LAC. Hsa_circ_0012673 promotes LAC proliferation by suppressing miR-22, which targets ErbB3.

miR-24-p53 pathway evoked by oxidative stress promotes lens epithelial cell apoptosis in age-related cataracts

MicroRNA-24 (miR-24) serves an important role in cell proliferation, migration and inflammation in various types of disease. In the present study, the biological function and molecular mechanism of miR-24 was investigated in association with the progression of age-associated cataracts. To the best of our knowledge the present study is the first to report that the expression of miR-24 was significantly increased in human anterior lens capsules affected by age-associated cataracts as well as lens epithelial cells (LECs) exposed to oxidative stress. Overexpression of miR-24 induced p53 expression and p53 was verified as a direct target of miR-24. Overexpression of miR-24 enhanced LEC death by directly targeting p53. The present study revealed that oxidative stress induced the upregulation of miR-24 and enhanced LEC death by directly targeting p53. These results suggest that the miR-24-p53 signaling pathway is involved in a novel mechanism of age-associated cataractogenesis and miR-24 may be a useful therapeutic target for age-associated cataracts.

miR-15b-5p facilitates the tumorigenicity by targeting RECK and predicts tumour recurrence in prostate cancer

MicroRNAs (miRNAs) have been reported to participate in many biological behaviours of multiple malignancies. Recent studies have shown that miR‐15b‐5p (miR‐15b) exhibits dual roles by accelerating or blocking tumour progression. However, the molecular mechanisms by which miR‐15b contributes to prostate cancer (PCa) are still elusive. Here, miR‐15b expression was found significantly up‐regulated in PCa in comparison with the normal samples and was positively correlated with age and Gleason score in patients with PCa. Notably, PCa patients with miR‐15b high expression displayed a higher recurrence rate than those with miR‐15b low expression (P = 0.0058). Knockdown of miR‐15b suppressed cell growth and invasiveness in 22RV1 and PC3 cells, while overexpression of miR‐15b reversed these effects. Then, we validated that RECK acted as a direct target of miR‐15b by dual‐luciferase assay and revealed the negative correlation of RECK with miR‐15b expression in PCa tissues. Ectopic expression of RECK reduced cell proliferation and invasive potential and partially abrogated the tumour‐promoting effects caused by miR‐15b overexpression. Additionally, miR‐15b knockdown inhibited tumour growth activity in a mouse PCa xenograft model. Taken together, our findings indicate that miR‐15b promotes the progression of PCa cells by targeting RECK and represents a potential marker for patients with PCa.

The Jun/miR-22/HuR regulatory axis contributes to tumourigenesis in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is a severe health problem worldwide. Clarifying the mechanisms for the deregulation of oncogenes and tumour suppressors in CRC is vital for its diagnosis, treatment, prognosis and prevention. Hu antigen R (HuR), which is highly upregulated in CRC, functions as a pivotal oncogene to promote CRC progression. However, the underlying cause of its dysregulation is poorly understood.

METHODS

In CRC tissue sample pairs, HuR protein levels were measured by Western blot and immunohistochemical (IHC) staining, respectively. HuR mRNA levels were also monitored by qRT-PCR. Combining meta-analysis and microRNA (miRNA) target prediction software, we predicted miRNAs that targeted HuR. Pull-down assay, Western blot and luciferase assay were utilized to demonstrate the direct binding of miR-22 on HuR's 3'-UTR. The biological effects of HuR and miR-22 were investigated both in vitro by CCK-8, EdU and Transwell assays and in vivo by a xenograft mice model. JASPAR and SABiosciences were used to predict transcriptional factors that could affect miR-22. Luciferase assay was used to explore the validity of putative Jun binding sites for miR-22 regulation. ChIP assay was performed to test the Jun's occupancy on the C17orf91 promoter.

RESULTS

We observed a significant upregulation of HuR in CRC tissue pairs and confirmed the oncogenic function of HuR both in vitro and in vivo. We found that an important tumour-suppressive miRNA, miR-22, was significantly downregulated in CRC tissues and inversely correlated with HuR in both CRC tissues and CRC cell lines. We demonstrated that miR-22 directly bound to the 3'-UTR of HuR and led to inhibition of HuR protein, which repressed CRC proliferation and migration in vitro and decelerated CRC xenografted tumour growth in vivo. Furthermore, we found that the onco-transcription factor Jun could inhibit the transcription of miR-22.

CONCLUSIONS

Our findings highlight the critical roles of the Jun/miR-22/HuR regulatory axis in CRC progression and may provide attractive potential targets for CRC prevention and treatment.

MicroRNA-511 Inhibits Cellular Proliferation and Invasion in Colorectal Cancer by Directly Targeting Hepatoma-Derived Growth Factor

Dysregulated microRNA (miRNA) expression is involved in the occurrence and development of colorectal cancer (CRC) through the regulation of various important physiological events. Hence, miRNAs may be used as effective targets for CRC treatment; however, this hypothesis warrants further investigation. miRNA-511 (miR-511) plays vital roles in the progression of different tumor types. However, the expression, exact role, and the mechanisms underlying the regulation of colorectal carcinogenesis and progression by miR-511 remain poorly understood. This study presents that miR-511 expression was decreased in CRC tissues and cell lines compared with that in adjacent nonneoplastic tissues and normal human colon epithelium cell lines, respectively. The enforced expression of miR-511 in CRC cells significantly reduced cell proliferation and invasion. Hepatoma-derived growth factor (HDGF) was mechanically validated as a direct target of miR-511 in CRC. Furthermore, miR-511 was negatively associated with HDGF in CRC tissues. The restored HDGF expression can abrogate the tumor-suppressive roles of miR-511 in CRC cells. More importantly, miR-511 overexpression suppressed the PI3K/AKT signaling pathway in CRC. These results suggest that miR-511 can potentially serve as a therapeutic target for the therapy of patients with CRC.

Comparative analysis of miRNA expression profiles in transgenic and non-transgenic rice using miRNA-Seq

Safety assessment for genetically modified organisms (GMOs) is required before their release. To date, miRNAs that play important roles in eukaryotic gene regulation have not been considered in the current assessment system. In this study, we identified 6 independent Bt and EPSPS GM rice lines using PCR and immune strip. We analyzed the expression levels of Cry1Ac and EPSPS using quantitative real-time PCR and western blot. Further, miRNAs from the developing seeds of the 6 GM rice lines and the wild-type line were investigated using deep sequencing and bioinformatic approaches. Although these GM lines have different types of integration sites, copy numbers, and levels of gene expression, 21 differentially expressed miRNAs have been found compared to wild type. There is no correlation between transgenic protein expression level and the quantity of differentially expressed miRNAs. This study provides useful data about the miRNA composition of GM plants, and it might be helpful for future risk assessments of miRNA-based GM plants.

Anticancer effect of miR-96 inhibitor in bladder cancer cell lines

The present study aimed to investigate the role of microRNA-96 (miR-96) in the proliferation, invasion and apoptosis of bladder cancer cell lines, and the associated mechanisms. The expression of miR-96 and human ether-à-go-go-related (HERG1) potassium channel in the normal uroepithelium SV-HUC-1 cell line, and bladder cancer T24 and 5637 cell lines were examined using reverse transcription-polymerase chain reaction or/and western blotting. Transfection with miR-96 inhibitor or scrambled control (SC) was used to study the biological activities of miR-96 in bladder cancer cell lines. MTT, flow cytometric and Transwell assays were applied to detect cell viability, apoptosis and invasion, respectively. A dual-luciferase reporter assay was applied to determine the association between miR-96 and HERG1 expression. As demonstrated, miR-96 was highly expressed in the two bladder cancer cell lines, particularly in T24 cells. Following transfection with miR-96 inhibitor, miR-96 expression was significantly reduced in the T24 cell line, compared with SC. The miR-96 inhibitor suppressed cell proliferation and invasion, promoted apoptosis and arrested the cell cycle at the G₁ phase. Consistently, HERG1 was also highly expressed in the two bladder cancer cell lines at the mRNA and protein level, but not in the normal uroepithelium cell line. The miR-96 inhibitor also significantly decreased HERG1 expression compared with SC. The results of the dual-luciferase reporter assay indicated that miR-96 directly targeted wild-type HERG1. In conclusion, miR-96 inhibitor exhibited anticancer effects on bladder cancer cells by inhibiting proliferation and invasion of cells, and promoting their apoptosis. HERG1 was an important target of miR-96. These results provided experimental evidence supporting miR-96 as a therapeutic target for patients with bladder cancer.

Tumor-suppressive miR-218-5p inhibits cancer cell proliferation and migration via EGFR in non-small cell lung cancer

Lung cancer remains the leading cause of cancer-related death worldwide, and non-small cell lung cancer (NSCLC) accounts for approximately 80% of lung cancer cases. Recently, microRNAs (miRNAs) have been consistently demonstrated to be involved in NSCLC and to act as either tumor oncogenes or tumor suppressors. In this study, we identified a specific binding site for miR-218-5p in the 3'-untranslated region of the epidermal growth factor receptor (EGFR). We further experimentally validated miR-218-5p as a direct regulator of EGFR. We also identified an inverse correlation between miR-218-5p and EGFR protein levels in NSCLC tissue samples. Moreover, we demonstrated that miR-218-5p plays a critical role in suppressing the proliferation and migration of lung cancer cells probably by binding to EGFR. Finally, we examined the function of miR-218-5p in vivo and revealed that miR-218-5p exerts an anti-tumor effect by negatively regulating EGFR in a xenograft mouse model. Taken together, the results of this study highlight an important role for miR-218-5p in the regulation of EGFR in NSCLC and may open new avenues for future lung cancer therapies.

miR-96 promotes breast cancer metastasis by suppressing MTSS1

Novel, non-invasive biomarkers with high sensitivity and specificity are critical for breast cancer treatment, and prognosis. MicroRNA (miR)-96 has been demonstrated to be highly expressed in several solid malignancies, including breast cancer. However, its expression and function in the metastasis and prognosis of breast cancer have not been fully explored, and its regulation mechanisms remain unclear. In the present study, the serum miR-96 expression in healthy controls, benign and malignant breast cancer types was compared by using reverse transcription-quantitative polymerase chain reaction. The effect of chemotherapy on miR-96 expression in breast cancer was also investigated. Result revealed that miR-96 expression was increased in malignant breast cancer types and reduced in patients following chemotherapy treatment. The effect of miR-96 manipulation on the migration of breast cancer cells was also investigated by using wound healing, and Transwell migration assays. These results revealed that the induced expression of miR96 led to enhanced wound closing and trans-membrane cell numbers. By using bioinformatics analysis, western blotting and immunohistochemical staining, the metastasis suppressor-1 (MTSS1) gene was identified to be the functional target of miR-96 in the promotion of cell migration. In conclusion, it was identified that miR-96 exhibited an increased level in serum samples of patients with malignant breast cancer in comparison with benign breast tumor types and health controls and may be substantially reduced by chemotherapy treatment, implying that it may be used as a prognostic marker in breast cancer. miR-96 overexpression may inhibit migration of breast cancer cells by downregulating MTSS1 expression.

Plant and Animal microRNAs (miRNAs) and Their Potential for Inter-kingdom Communication

microRNAs (miRNAs) comprise a class of ~18-25 nucleotide (nt) single-stranded non-coding RNAs (sncRNAs) that are the smallest known carriers of gene-encoded, post-transcriptional regulatory information in both plants and animals. There are many fundamental similarities between plant and animal miRNAs-the miRNAs of both kingdoms play essential roles in development, aging and disease, and the shaping of the transcriptome of many cell types. Both plant and animal miRNAs appear to predominantly exert their genetic and transcriptomic influences by regulating gene expression at the level of messenger RNA (mRNA) stability and/or translational inhibition. Certain miRNA species, such as miRNA-155, miRNA-168, and members of the miRNA-854 family may be expressed in both plants and animals, suggesting a common origin and functional selection of specific miRNAs over vast periods of evolution (for example, Arabidopsis thaliana-Homo sapiens divergence ~1.5 billion years). Although there is emerging evidence for cross-kingdom miRNA communication-that plant-enriched miRNAs may enter the diet and play physiological and/or pathophysiological roles in human health and disease-some research reports repudiate this possibility. This research paper highlights some recent, controversial, and remarkable findings in plant- and animal-based miRNA signaling research with emphasis on the intriguing possibility that dietary miRNAs and/or sncRNAs may have potential to contribute to both intra- and inter-kingdom signaling, and in doing so modulate molecular-genetic mechanisms associated with human health and disease.

miR-96-5p prevents hepatic stellate cell activation by inhibiting autophagy via ATG7

Activation of hepatic stellate cell (HSC), which is the main source of extracellular matrix, plays a pivotal role in liver fibrogenesis. Autophagy of hepatic stellate cell has been recently implicated in liver fibrosis, but the regulation of hepatic stellate cell autophagy during this process remains poorly understood. Here, we first identified miR-96-5p as an aberrantly expressed miRNA in fibrotic liver tissues. Next, we transfected miR-96-5p mimic into human hepatic stellate cell line LX-2 and observed decreased protein and mRNA levels of α-SMA and Col1A1. In addition, transfection of miR-96-5p mimic significantly reduced autophagy activity of LX-2 cells, while transfection of miR-96-5p inhibitor promoted LX-2 cell autophagy. Moreover, autophagy-related protein 7 (ATG7) was predicted as a potential target of miR-96-5p and luciferase assay confirmed its direct interaction with miR-96-5p. Finally, reintroduction of ATG7 into LX-2 cells reversed miR-96-5p-mediated inhibition of autophagy as well as α-SMA and Col1A1 expression. In conclusion, we demonstrated that miR-96-5p can inhibit hepatic stellate cell activation by blocking autophagy via ATG7. These findings provide new insight into the development of miRNA-based anti-fibrotic strategies.

KEY MESSAGES

• Altered miRNA expression profile is observed in fibrotic liver tissues. • miR-96-5p can inhibit HSC activation. • Autophagy of HSC is repressed by miR-96-5p during activation. • ATG7 is a direct target of miR-96-5p. • ATG7 can rescue miR-96-5p-mediated inhibition of autophagy and HSC activation.

Decoding colorectal cancer epigenomics

Colorectal cancer (CRC) is very heterogeneous and presents different types of epigenetic alterations including DNA methylation, histone modifications and microRNAs. These changes are considered as characteristics of various observed clinical phenotypes. Undoubtedly, the discovery of epigenetic pathways with novel epigenetic-related mechanisms constitutes a promising advance in cancer biomarker discovery. In this review, we provide an evidence-based discussing of the current understanding of CRC epigenomics and its role in initiation, epithelial-to-mesenchymal transition and metastasis. We also discuss the recent findings regarding the potential clinical perspectives of these alterations as potent biomarkers for CRC diagnosis, prognosis, and therapy in the era of liquid biopsy.

Development of Novel Therapeutic Agents by Inhibition of Oncogenic MicroRNAs

MicroRNAs (miRs, miRNAs) are regulatory small noncoding RNAs, with their roles already confirmed to be important for post-transcriptional regulation of gene expression affecting cell physiology and disease development. Upregulation of a cancer-causing miRNA, known as oncogenic miRNA, has been found in many types of cancers and, therefore, represents a potential new class of targets for therapeutic inhibition. Several strategies have been developed in recent years to inhibit oncogenic miRNAs. Among them is a direct approach that targets mature oncogenic miRNA with an antisense sequence known as antimiR, which could be an oligonucleotide or miRNA sponge. In contrast, an indirect approach is to block the biogenesis of miRNA by genome editing using the CRISPR/Cas9 system or a small molecule inhibitor. The development of these inhibitors is straightforward but involves significant scientific and therapeutic challenges that need to be resolved. In this review, we summarize recent relevant studies on the development of miRNA inhibitors against cancer.

miR-769-5p suppressed cell proliferation, migration and invasion by targeting TGFBR1 in non-small cell lung carcinoma

MicroRNAs (miRNAs) are key regulators of multiple cancers, including non-small cell lung carcinoma (NSCLC). The aim of this study was to determine the expression pattern of miR-769-5p in NSCLC and to investigate its biological role during tumorigenesis. We showed that miR-769-5p was significantly downregulated and predicted poor prognosis in NSCLC compared with corresponding normal tissues. We then investigated its function and found that miR-769-5p significantly inhibited cell proliferation, migration and invasion in vitro and reduced tumor growth and metastasis in vivo. Furthermore, we explored the molecular mechanisms by which miR-769-5p contributes to NSCLC suppression and identified TGFBR1 as a direct target gene of miR-769-5p. Finally, we showed that TGFBR1 had opposite effects to those of miR-769-5p on lung cancer cells, suggesting that miR-769-5p might inhibit lung tumorigenesis by silencing TGFBR1. Taken together, our results demonstrated that miR-769-5p plays a pivotal role in NSCLC by inhibiting cell proliferation, migration and invasion by targeting TGFBR1.

Disruption of the c-Myc/miR-200b-3p/PRDX2 regulatory loop enhances tumor metastasis and chemotherapeutic resistance in colorectal cancer

BACKGROUND

Metastasis is a major threat to colorectal cancer (CRC) patients. We have reported that peroxiredoxin-2 (PRDX2) is associated with CRC invasion and metastasis. However, the mechanisms regulating PRDX2 expression remain unclear. We investigate whether microRNAs (miRNAs) regulate PRDX2 expression in CRC progression.

METHODS

Quantitative real-time polymerase chain reaction (qPCR) was used to measure microRNA-200b-3p (miR-200b-3p) expression. Immunohistochemistry (IHC) was performed to detect c-Myc and PRDX2 protein levels in CRC tissue samples (n = 97). Western blot was used to quantify PRDX2, c-Myc, AKT2/GSK3β pathway-associated proteins and epithelial-mesenchymal transition (EMT)-related proteins in CRC cells. Luciferase reporter assays were used to analyze the interaction between miR-200b-3p and 3'untranslated region (3'UTR) of PRDX2 mRNA and AKT2 mRNA as well as c-Myc and the miR-200b-3p promoter. Chromatin immunoprecipitation (ChIP) assay was used to evaluate binding of c-Myc to the miR-200b-3p promoter. Invasive assay and metastatic model were used to assess invasive and metastatic capacities of CRC cells in vitro and in vivo. Moreover, drug-induced apoptosis was measured by flow cytometry.

RESULTS

We found that miR-200b-3p was significantly downregulated, whereas c-Myc and PRDX2 were upregulated in metastatic CRC cells and CRC tissues compared to their counterparts. An inverse correlation existed between c-Myc and miR-200b-3p, and between miR-200b-3p and PRDX2. We also found that PRDX2 was a target of miR-200b-3p. Importantly, overexpression of nontargetable PRDX2 eliminated the suppressive effects of miR-200b-3p on proliferation, invasion, EMT, chemotherapeutic resistance and metastasis of CRC cells. Moreover, c-Myc bound to the promoter of miR-200b-3p and repressed its transcription. In turn, miR-200b-3p disrupted the stability of c-Myc protein by inducing c-Myc protein threonine 58 (T58) phosphorylation and serine 62 (S62) dephosphorylation via AKT2/GSK3β pathway.

CONCLUSIONS

Our findings reveal that the c-Myc/miR-200b/PRDX2 loop regulates CRC progression and its disruption enhances tumor metastasis and chemotherapeutic resistance in CRC.

MicroRNA expression profiles in benign prostatic hyperplasia

Although alterations in microRNA (miRNA) expression have been previously investigated prostate cancer, the expression of miRNAs specifically in benign prostate hyperplasia (BPH) of the prostatic stroma remains to be fully elucidated. In the present study, miRNAs and gene expression profiles were investigated using microarray analysis and reverse transcription quantitative‑polymerase chain reaction (RT‑qPCR) in BPH tissue to clarify the associations between miRNA expression and target genes. Prostate tissue samples from five patients with BPH and five healthy men were analyzed using human Affymetrix miRNA and mRNA microarrays and differentially expressed miRNAs were validated using RT‑qPCR with 30 BPH and 5 healthy control samples. A total of 8 miRNAs, including miRNA (miR)‑96‑5p, miR‑1271‑5p, miR‑21‑3p, miR‑96‑5p, miR‑181a‑5p, miR‑143‑3p, miR‑4428 and miR‑106a‑5p were upregulated and 8 miRNAs (miR‑16‑5p, miR‑19b‑5p, miR‑940, miR‑25, miR‑486‑3p, miR‑30a‑3p, let‑7c and miR‑191) were downregulated. Additionally, miR‑96‑5p was demonstrated to have an inhibitory effect on the mRNA expression levels of the following genes: Mechanistic target of rapamycin (MTOR), RPTOR independent companion of MTOR complex 2, syntaxin 10, autophagy‑related protein 9A, zinc finger E‑box binding homeobox 1, caspase 2 and protein kinase c ε. Additionally, 16 differentially expressed miRNAs were identified using RT‑qPCR analysis. This preliminary study provides a solid basis for a further functional study to investigate the underlying regulatory mechanisms of BPH.

MicroRNA-19a acts as a prognostic marker and promotes prostate cancer progression via inhibiting VPS37A expression

Prostate cancer (PCa) is a leading cause of cancer-related deaths among males worldwide. However, the molecular mechanisms underlying the progression of PCa remain unclear. Despite several reported miRNAs in prostate cancer, these reports lacked system-level identification of differentially expressed miRNAs in large sample size. Moreover, it's still largely unknown how miRNAs result in tumorigenesis and progression of PCa. Therefore, by analyzing three public databases, we identified 16 upregulated miRNAs and 13 downregulated miRNAs, and validated miR-19a was one of the most upregulated miRNAs using qRT-PCR. The dual-luciferase reporter assays indicated VPS37A was a potential target of miR-19a. Functional assays revealed miR-19a served as an oncogene by inhibiting VPS37A. Notably, a significant inverse correlation of miR-19a and VPS37A expression was observed in PCa specimens. Moreover, miR-19a-high and VPS37A-low phenotypes were associated with poor prognosis with biochemical recurrence-free probability. In this study, we confirmed the oncogenic role of miR-19a via targeting VPS37A in PCa, identifying miR-19a and VPS37A as diagnosis and therapeutic biomarkers for PCa.

MicroRNA regulation of K-Ras in pancreatic cancer and opportunities for therapeutic intervention

The Ras family of GTPases is involved in cell proliferation, cell survival, and angiogenesis. It is upregulated in several cancers, including pancreatic cancer (PC) and leads to uncontrolled growth and aggressiveness. PC is well known to be a lethal disease with poor prognosis, plagued by limited therapeutic modalities. MicroRNAs (miRNAs), which are short non-coding RNA molecules, have recently emerged as regulators of signaling networks and have shown potential to target pathway components for therapeutic use in several malignancies. K-Ras mutations are widespread in PC cases (90%), with mutations detectable as early as pancreatic intraepithelial neoplasias and in later metastatic stages alike; therefore, these mutations in K-Ras are obvious drivers and potential targets for PC therapy. Several K-Ras targeting miRNAs have lately been discovered, and many of them have shown promise in combating pancreatic tumor growth in vitro and in mouse models. However, the field of miRNA therapy is still in its infancy, and miRNA mimics or anti-miRNA oligonucleotides that target Ras pathway have thus far not been evaluated in PC patients. In this review, we summarize the role of several miRNAs that regulate oncogenic K-Ras signaling in PC, with their prospective roles as therapeutic agents for targeting K-Ras pathway.

Examining plasma microRNA markers for colorectal cancer at different stages

Circulating microRNAs (miRNAs) have emerged as promising biomarkers; however, few miRNAs have been reproducible and can be used in clinical practice. In this study, we screened the levels of 754 miRNAs using TaqMan array in 50 individual plasma samples from 10 demographically matched healthy controls and 40 colorectal cancer (CRC) patients (10 each of stage I-IV) and identified 22 miRNAs associated with the presence of and stages of CRC. Then we performed the validation for 11 miRNAs in an independent cohort including 187 CRC cases and 47 healthy controls. Comprehensive analyses showed that plasma miR-96 distinguished stage I-IV CRC from healthy controls with an area under curve (AUC) of 0.740; miR-203 separated stage III-IV CRC patients from stage I-II with an AUC of 0.757; and miR-141 differentiated stage IV CRC from stage I-III patients with an AUC of 0.851. Survival analyses showed that plasma miR-96 and miR-200b were independent prognostic factors for overall survival. Thus, we propose four miRNAs (miR-96, miR-203, miR-141 and miR-200b) as clinically validated circulating biomarkers for CRC prognosis that warrant further evaluation for clinical utility.

miR-767-3p Inhibits Growth and Migration of Lung Adenocarcinoma Cells by Regulating CLDN18

Claudin18 (CLDN18) is necessary for intercellular junctions and is reported to be involved in cell migration and metastasis, making it like an oncogene in various cancer types. However, the biological function and regulatory mechanisms of CLDN18 in lung adenocarcinoma are not yet clear. In this study, we found downregulation of miR-767-3p and upregulation of CLDN18 in lung adenocarcinoma tissue and cell lines. In addition, there was a negative correlation between the expression of miR-767-3p and CLDN18 in lung adenocarcinoma. Double luciferase reporter gene analysis showed that miR-767-3p modulates the expression of CLDN18 by binding its 3'-untranslated regions (3'-UTR). Knockdown of CLDN18 results in a decrease in the growth, migration, and invasion of lung adenocarcinoma cells. Although overexpression of miR-767-3p inhibits lung adenocarcinoma cell growth and migration, these effects can be rescued by reexpressing CLDN18. In summary, the data suggest that miR-767-3p inhibits tumor cell proliferation, migration, and invasion by targeting CLDN18, providing a promising therapeutic target for lung adenocarcinoma.

Post-transcriptional Regulation of Genes Related to Biological Behaviors of Gastric Cancer by Long Noncoding RNAs and MicroRNAs

Noncoding RNAs play critical roles in regulating protein-coding genes and comprise two major classes: long noncoding RNAs (lncRNAs) and microRNAs (miRNAs). LncRNAs regulate gene expression at transcriptional, post-transcriptional, and epigenetic levels via multiple action modes. LncRNAs can also function as endogenous competitive RNAs for miRNAs and indirectly regulate gene expression post-transcriptionally. By binding to the 3'-untranslated regions (3'-UTR) of target genes, miRNAs post-transcriptionally regulate gene expression. Herein, we conducted a review of post-transcriptional regulation by lncRNAs and miRNAs of genes associated with biological behaviors of gastric cancer.

Dietary miR-451 protects erythroid cells from oxidative stress via increasing the activity of Foxo3 pathway

One fundamental issue in public health is the safety of food products derived from plants and animals. A recent study raised a concern that microRNAs, which widely exist in everyday foods, may alter consumers' functions. However, some studies have strongly questioned the likelihood of dietary uptake of functional microRNAs in mammals. Here we use a microRNA gene knockout animal model to show that miR-144/451 null mice can orally uptake miR-451 from a daily chow diet, and ingestion of wild type blood, that contains abundant miR-451, also enhances the level of miR-451 in the circulating blood of knockout mice. Moreover, reducing miR-451 level in miR-144/451 knockout blood by consuming food lacking miR-451 reduces the anti-oxidant capacity of miR-144/451 null red blood cells by targeting the 14-3-3ζ/Foxo3 pathway, while increasing miR-451 level via gavage-feeding of wild type blood increases the anti-oxidant capacity of miR-144/451 null red blood cells. We conclude that 1) some miRNAs in food can pass through the gastrointestinal tract into the blood to affect consumers' function and 2) microRNA knockout animals such as miR-144/451 null mice can acquire the deleted genetic information from daily foods, which might alter the results and conclusions from the studies using such animals.

Role of MicroRNA Regulation in Obesity-Associated Breast Cancer: Nutritional Perspectives

Breast cancer is the most common malignancy diagnosed in women, and the incidence of breast cancer is increasing every year. Obesity has been identified as one of the major risk factors for breast cancer progression. The mechanisms by which obesity contributes to breast cancer development is not yet understood; however, there are a few mechanisms counted as potential producers of breast cancer in obesity, including insulin resistance, chronic inflammation and inflammatory cytokines, adipokines, and sex hormones. Recent emerging evidence suggests that alterations in microRNA (miRNA) expressions are found in several diseases, including breast cancer and obesity; however, miRNA roles in obesity-linked breast cancer are beginning to unravel. miRNAs are thought to be potential noninvasive biomarkers for diagnosis and prognosis of cancer patients with comorbid conditions of obesity as well as therapeutic targets. Recent studies have evidenced that nutrients and other dietary factors protect against cancer and obesity through modulation of miRNA expressions. Herein, we summarize a comprehensive overview of up-to-date information related to miRNAs and their molecular targets involved in obesity-associated breast cancer. We also address the mechanisms by which dietary factors modulate miRNA expression and its protective roles in obesity-associated breast cancer. It is hoped that this review would provide new therapeutic strategies for the treatment of obesity-associated breast cancer to reduce the burden of breast cancer.

MicroRNAs and the metabolic hallmarks of aging

Aging, the natural process of growing older, is characterized by a progressive deterioration of physiological homeostasis at the cellular, tissue, and organismal level. Metabolically, the aging process is characterized by extensive changes in body composition, multi-tissue/multi-organ insulin resistance, and physiological declines in multiple signaling pathways including growth hormone, insulin/insulin-like growth factor 1, and sex steroids regulation. With this review, we intend to consolidate published information about microRNAs that regulate critical metabolic processes relevant to aging. In certain occasions we uncover relationships likely relevant to aging, which has not been directly described before, such as the miR-451/AMPK axis. We have also included a provocative section highlighting the potential role in aging of a new designation of miRNAs, namely fecal miRNAs, recently discovered to regulate intestinal microbiota in mammals.

MicroRNA-143 shows tumor suppressive effects through inhibition of oncogenic K-Ras in pituitary tumor

MicroRNAs (miRNAs) are a class of small non-coding RNA molecules, about 21-25 nucleotides in length. Accumulating evidence demonstrated that dysregulation or dysfunction of miRNAs are involved in various diseases, including cancer. MiR-143, recently has been reported to function as an important tumor suppressor in prostate cancer, pancreatic ductal adenocarcinoma and other kinds of cancers, but rarely systematically studied in pituitary tumor. In the present study, we firstly found that miR-143 was significantly down-regulated in pituitary tumor tissues and cell lines (GH3 and MMQ). Then, subsequent studies revealed that miR-143 inhibits cell proliferation and promotes apoptosis in both GH3 and MMQ cells. In addition, K-Ras, one of the most important oncogenes involved in many kinds of cancers, was found to be suppressed by miR-143 in pituitary tumor. Furthermore, overexpression of K-Ras greatly reversed the suppressive effect of miR-143 on pituitary tumor cells. In summary, our study demonstrated that miR-143 functions as a tumor suppressor and directly targets K-Ras in human pituitary tumor.

MicroRNA-30a Inhibits Colorectal Cancer Metastasis Through Down-Regulation of Type I Insulin-Like Growth Factor Receptor

BACKGROUND

miR-30a expression is down-regulated and regulates tumor suppressors in various cancers.

AIM

We investigated the mechanisms underlying the biological role of miR-30a in CRC.

METHODS

MicroRNA, mRNA, and protein expression were analyzed by quantitative real-time PCR and Western blot. The migration and invasion abilities of CRC were determined by wound healing assay, and trans-well migration and invasion. A luciferase reporter assay was used to confirm the targets of miR-30a.

RESULTS

miR-30a expression was significantly down-regulated in CRC tissues and in CRC tissue with lymph node metastasis compared to CRC tissue without metastasis. Overexpression of miR-30a suppressed migration and invasion through insulin-like growth factor 1 receptor (IGF1R) in CRC cells. miR-30a suppresses IGF1R protein expression and inhibits β-catenin or p-AKT and increases E-cadherin expression. The IGF1R expression level is also up-regulated in CRC tumors and inversely correlated with miR-30a in CRC specimens.

CONCLUSIONS

miR-30a functions as a tumor-suppressive miRNA, which may provide a therapeutic strategy for metastasis of CRC.

Role of AP-2α and MAPK7 in the regulation of autocrine TGF-β/miR-200b signals to maintain epithelial-mesenchymal transition in cholangiocarcinoma

Background

Cholangiocarcinoma (CCA) is characterized by early lymphatic, metastasis, and low survival rate. Epithelial-mesenchymal transition (EMT) is able to induce tumor metastasis. Although the TGF-β/miR-200 signals promote EMT in various types of cancer, the regulatory mechanism in CCA is still unclear.

Methods

Expression of miR-200b, TGF-β, and EMT markers were measured in tumor samples and cell lines by qRT-PCR and western blot. CCK8 assay was performed to measure the cell viability. Transwell assay was used to evaluate migration and invasion. The target genes of miR-200b and transcription factor of TGF-β were analyzed using dual-luciferase reporter system.

Results

We have demonstrated that CCA exhibited remarkable EMT phenotype and miR-200b was reduced in CCA patients (n = 20) and negatively correlated to TGF-β. Moreover, two CCA cells, HCCC, and RBE, with epithelial appearances treated with TGF-β, showed fibroblastic-like cell morphology with downregulated miR-200b expression. Forced expression of miR-200b abrogated TGF-β-induced EMT initiation, with decreased cell proliferation, migration, and invasion in vitro. Also, TFAP2A (encode AP-2α) and MAPK7 were found to be targeted by miR-200b to downregulate EMT and AP-2α inhibited miR-200b by directly promoting transcription of TGFB1. Overexpression of MAPK7 significantly reversed miR-200b-induced inhibition of EMT, migration, and proliferation by increasing the expression of TGF-β, cyclin D1, and Cdk2. Further, the administration of miR-200b induced a remarkably tumor regression in vivo and reduced the effect of TGF-β-related EMT in AP-2α and MAPK7-dependent manner.

Conclusions

Our study highlights that miR-200b-based gene therapy is effective in the treatment of CCA.

MicroRNA Expression in Laser Micro-dissected Breast Cancer Tissue Samples - a Pilot Study

Breast cancer continues to represent a significant public health burden despite outstanding research advances regarding the molecular mechanisms of cancer biology, biomarkers for diagnostics and prognostic and therapeutic management of this disease. The studies of micro RNAs in breast cancer have underlined their potential as biomarkers and therapeutic targets; however most of these studies are still done on largely heterogeneous whole breast tissue samples. In this pilot study we have investigated the expression of four micro RNAs (miR-21, 145, 155, 92) known to be involved in breast cancer, in homogenous cell populations collected by laser capture microdissection from breast tissue section slides. Micro RNA expression was assessed by real time PCR, and associations with clinical and pathological characteristics were also explored. Our results have confirmed previous associations of miR-21 expression with poor prognosis characteristics of breast cancers such as high stage, large and highly proliferative tumors. No statistically significant associations were found with the other micro RNAs investigated, possibly due to the small sample size of our study. Our results also suggest that miR-484 could be a suitable endogenous control for data normalization in breast tissues, these results needing further confirmation by future studies. In summary, our pilot study showed the feasibility of detecting micro RNAs expression in homogenous laser captured microdissected invasive breast cancer samples, and confirmed some of the previously reported associations with poor prognostic characteristics of breast tumors.

miR-92b-3p acts as a tumor suppressor by targeting Gabra3 in pancreatic cancer

BACKGROUND

MicroRNAs (miRNAs) can act as oncogenes or tumor suppressors by controlling cell proliferation, differentiation, metastasis and apoptosis, and miRNA dysregulation is involved in the development of pancreatic cancer (PC). Our previous study demonstrated that Gabra3 plays critical roles in cancer progression. However, whether Gabra3 is regulated by miRNAs in PC remains unknown.

METHODS

The expression levels of miR-92b-3p and Gabra3 were measured by quantitative PCR (qPCR), immunoblotting, in situ hybridization (ISH) and immunohistochemistry (IHC). The proliferation rate of PC cells was detected by MTS assay. Wound-healing and transwell assays were used to examine the invasive abilities of PC cells. Dual-luciferase reporter assays were used to determine how miR-92b-3p regulates Gabra3. Xenograft mouse models were used to assess the role of miR-92b-3p in PC tumor formation in vivo.

RESULTS

Here, we provide evidence that miR-92b-3p acted as a tumor suppressor in PC by regulating Gabra3 expression. MiR-92b-3p expression levels were lower in PC tissues than corresponding noncancerous pancreatic (CNP) tissues and were associated with a poor prognosis in PC patients. MiR-92b-3p overexpression suppressed the proliferation and invasion of PC cells in both in vivo and in vitro models. Conversely, miR-92b-3p knockdown induced an aggressive phenotype in PC cells. Mechanistically, miR-92b-3p overexpression suppressed Gabra3 expression, which then led to the inactivation of important oncogenic pathways, including the AKT/mTOR and JNK pathways.

CONCLUSION

Our results suggest that miR-92b-3p acted as a tumor suppressor by targeting Gabra3-associated oncogenic pathways; these results provide novel insight into future treatments for PC patients.

Expression and function of the miR-143/145 cluster in vitro and in vivo in human breast cancer

MicroRNAs (miRNAs) are small non-coding RNAs that function as post-transcriptional regulators of gene expression and are dysregulated in cancer. Studies of miRNAs to explore their potential as diagnostic and prognostic markers are of great scientific interest. Here, we investigate the functional properties and expression of the miR-143/145 cluster in breast cancer (BC) in vitro and in vivo. The ER positive MCF7, the HER2 positive SK-BR-3, and the triple negative cell line MDA-MB-231 were used to assess cell proliferation and cell invasion. Expression of miRNA in 108 breast cancers in the Norwegian Women and Cancer Study and 44 benign tissue controls were analyzed by microarray and validated by RT-PCR. Further, in situ hybridization (ISH) was used to study the cellular and subcellular distribution of the miRNAs. In vitro, miR-143 promoted proliferation of MCF7 and MDA-MB-231 cells, whereas miR-145 and the cotransfection of both miRNAs inhibited proliferation in all three cell lines. The cells’ invasive capacity was reduced after transfection and cotransfection of the miRNAs. In line with the tumor suppressive functions in vitro, the expression of miR-143 and miR-145 was lower in malignant compared to benign breast tissue, and lower in the more aggressive tumors with higher tumor grade, loss of ER and the basal-like phenotype. ISH revealed miR-143 to be cytoplasmatic and predominantly expressed in luminal cells in benign tissue, whilst miR-145 was nuclear and with strong staining in myoepithelial cells. Both miRNAs were present in malignant epithelial cells and stromal fibroblasts in BC. This study demonstrates that miR-143 and -145 have functional properties and expression patterns typical for tumor suppressors, but the function is influenced by cellular factors such as cell type and miRNA cotransfection. Further, the nuclear functions of miR-145 should be explored for a more complete understanding of the complexity of miRNA regulation and function in BC.

Molecular genetics and cellular events of K-Ras-driven tumorigenesis

Cellular transformation and the accumulation of genomic instability are the two key events required for tumorigenesis. K-Ras (Kirsten-rat sarcoma viral oncogene homolog) is a prominent oncogene that has been proven to drive tumorigenesis. K-Ras also modulates numerous genetic regulatory mechanisms and forms a large tumorigenesis network. In this review, we track the genetic aspects of K-Ras signaling networks and assemble the sequence of cellular events that constitute the tumorigenesis process, such as regulation of K-Ras expression (which is influenced by miRNA, small nucleolar RNA and lncRNA), activation of K-Ras (mutations), generation of reactive oxygen species (ROS), induction of DNA damage and apoptosis, induction of DNA damage repair pathways and ROS detoxification systems, cellular transformation after apoptosis by the blebbishield emergency program and the accumulation of genomic/chromosomal instability that leads to tumorigenesis.

Tumor suppressive protein phosphatases in human cancer: Emerging targets for therapeutic intervention and tumor stratification

Aberrant protein phosphorylation is one of the hallmarks of cancer cells, and in many cases a prerequisite to sustain tumor development and progression. Like protein kinases, protein phosphatases are key regulators of cell signaling. However, their contribution to aberrant signaling in cancer cells is overall less well appreciated, and therefore, their clinical potential remains largely unexploited. In this review, we provide an overview of tumor suppressive protein phosphatases in human cancer. Along their mechanisms of inactivation in defined cancer contexts, we give an overview of their functional roles in diverse signaling pathways that contribute to their tumor suppressive abilities. Finally, we discuss their emerging roles as predictive or prognostic markers, their potential as synthetic lethality targets, and the current feasibility of their reactivation with pharmacologic compounds as promising new cancer therapies. We conclude that their inclusion in clinical practice has obvious potential to significantly improve therapeutic outcome in various ways, and should now definitely be pushed forward.

miR-143 and miR-145 inhibit gastric cancer cell migration and metastasis by suppressing MYO6

Metastasis is a major clinical obstacle responsible for the high mortality and poor prognosis of gastric cancer (GC). MicroRNAs (miRNAs) are critical mediators of metastasis that act by modulating their target genes. In this study, we found that miR-143 and miR-145 act via a common target gene, MYO6, to regulate the epithelial–mesenchymal transition (EMT) and inhibit metastasis. We determined that miR-143 and miR-145 were downregulated in GC, and the ectopic expression of miR-143 and/or miR-145 inhibited GC cell migration and metastasis. Furthermore, MYO6 was identified as a direct common target of miR-143 and miR-145 and was elevated in GC. Silencing of MYO6 resulted in a metastasis-suppressive activity similar to that of miR-143 and miR-145, while restoring MYO6 attenuated the anti-metastatic or anti-EMT effects caused by miR-143 and miR-145. Clinically, an inverse correlation was observed between miR-143/145 levels and MYO6 levels in GC tissues, and either miR-143/145 downregulation or MYO6 upregulation was associated with more malignant phenotypes in patients with GC. In conclusion, miR-143 and miR-145 suppress GC cell migration and metastasis by inhibiting MYO6 expression and the EMT, which provides a novel mechanism and promising therapeutic target for the treatment of GC metastasis.

miR-31 Functions as an Oncomir Which Promotes Epithelial-Mesenchymal Transition via Regulating BAP1 in Cervical Cancer

MicroRNA-31 (miR-31) functions as tumor suppressors or oncogenes that are involved in tumor behavior. However, the function of miR-31 in cervical carcinogenesis remains unclear. The aim of this study was to validate the potential role of miR-31 and BRCA1-associated protein-1 (BAP1) on regulating epithelial-mesenchymal transition (EMT) in cervical cancer. In the present study, qRT-PCR assay revealed that the expression of miR-31 was upregulated in human cervical cancer cells and clinical tissues. Results of wound healing and cell migration assay revealed that knockdown of miR-31 inhibited cell metastasis and migration. Bioinformatic and dual-luciferase reporter gene assay showed that BAP1 was the direct target of miR-31. Furthermore, the results revealed that miR-31 promoted proliferation and EMT in cervical cancer cells and accelerated the development of tumor growth in vivo xenograft experiment by inhibiting BAP1 expression. Overall, these results highlight an important role of miR-31 functioning as an oncomir which could promote EMT in cervical cancer via downregulating BAP1 expression. Thus, downregulation of miR-31 could be a novel approach for the molecular treatment of cervical cancers and other malignancies.

Altered microRNA profiles during early colon adenoma progression in a porcine model of familial adenomatous polyposis

MicroRNAs are dysregulated in various cancers including colorectal cancer, and are potential useful biomarkers of disease development. We used next generation sequencing to investigate miRNA expression profiles in low- and high-grade intraepithelial dysplastic polyps from pigs carrying a mutation in the adenomatous polyposis coli tumour suppressor (APC¹³¹¹ , orthologous to human APC¹³⁰⁹ ) that model an inherited predisposition to colorectal cancer, familial adenomatous polyposis. We identified several miRNAs and their isomiRs significantly (P < 0.05) differentially expressed between low and high-grade intraepithelial dysplastic polyps. Of these, ssc-let-7e, ssc-miR-98, ssc-miR-146a-5p, ssc-miR-146b, ssc-miR-183 and ssc-miR-196a were expressed at higher level and ssc-miR-126-3p at lower level in high-grade intraepithelial dysplastic polyps. Functional miRNA target analysis revealed significant (P < 0.001) over-representation of cancer-related pathways, including 'microRNAs in cancer', 'proteoglycans in cancer', 'pathways in cancer' and 'colorectal cancer'. This is the first study to reveal miRNAs associated with premalignant transformation of colon polyps.

Long non-coding RNA PCAT-1 contributes to tumorigenesis by regulating FSCN1 via miR-145-5p in prostate cancer

Prostate cancer associated lncRNA transcript 1 (PCAT-1) has been identified as an oncogenic long non-coding RNA (lncRNA) in some solid tumors, including prostate cancer (PC). However, the molecular mechanism of PCAT-1 involved in PC is poorly defined. In this study, we found that PCAT-1 expression was up-regulated and miR-145-5p expression was down-regulated in PC tissues and cells. Function analysis indicated that PCAT-1 overexpression promoted proliferation, migration, invasion and inhibited apoptosis of PC cells. Rescue experiments demonstrated that miR-145-5p restoration attenuated the promotive effects of PCAT1 on PC progression, while Fascin-1 (FSCN1) upregulation relieved the anti-cancer role of miR-145-5p in PC. Mechanical analysis discovered that PCAT-1 could act as a miR-145-5p sponge to modulate FSCN1 expression. In conclusion, these findings suggested that PCAT-1 accelerated PC cell proliferation, migration, invasion and suppressed apoptosis by up-regulating FSCN1 mediated via miR-145-5p, hinting a potential therapeutic strategy for PC patients.

Involvement of miR-451 in resistance to paclitaxel by regulating YWHAZ in breast cancer

MicroRNAs (miRNAs) have been identified as major post-transcriptional regulators of the initiation and progression of human cancers, including breast cancer. However, the detail role of miR-451 has not been fully elucidated in breast cancer. In this study, we aimed to investigate the biological role and molecular mechanisms of miR-451 in drug resistance in breast cancer cell lines and in xenograft model. We show that miR-451 is decreased in human breast cancer specimens and in paclitaxel-resistant (PR) cells. Ectopic expression of miR-451 could inhibit the cell migration and invasion, promoted apoptosis, induced cell-cycle arrest Furthermore, tyrosine3-monooxygenase/tryptophan5-monooxygenase activation protein zeta (YWHAZ) was identified as a direct target of miR-451. Remarkably, the expression of YWHAZ is inversely correlated with the level of miR-451 in human breast cancer samples. Co-treatment with miR-451 mimics and YWHAZ-siRNA significantly enhanced YWHAZ knockdown in both SKBR3/PR and MCF-7/PR cells Moreover, miR-451 markedly inhibited expression of β-catenin via YWHAZ and subsequently inhibited downstream gene cyclin D1, c-Myc expression. The results of xenograft model in vivo showed that intratumor injection of miR-451 agomir induced a tumor-suppressive effect in SKBR3/PR drug-resistant xenograft model. Taken together, our findings suggested that miR-451 might be considered as important and potential target in paclitaxel-resistant breast cancer treatment.

MiR-216b functions as a tumor suppressor by targeting HMGB1-mediated JAK2/STAT3 signaling way in colorectal cancer

MiR-216b is implicated in the development of multiple types of cancers, however, a role for miR-216b in colorectal cancer (CRC) remains elusive. The present study aimed to investigate the function and underlying mechanism of miR-216b in human CRC. In this study, we found miR-216b in CRC tissues and cell lines was markedly decreased compared with corresponding adjacent normal tissues (ANTs) and colonic mucosal epithelial cell line (FHC), and was obviously associated with the TNM stage, lymph node metastases, differentiation and poor overall survival (OS) (P<0.05). Furthermore, we demonstrated that miR-216b inhibited cell proliferation, migration, invasion and angiogenesis by targeting HMGB1 which was highly expressed in CRC. Additionally, we proved that miR-216b promoted the development and progression of CRC, at least partially through HMGB1-mediated JAK2/STAT3 pathway. Lastly, we showed that plasma miR-216b expression was reduced in CRC when compared to healthy controls and might be a potential diagnostic biomarker for CRC. The findings indicated that miR-216b might function as a suppressor in CRC and could serve as a promising diagnostic and prognostic biomarker for CRC.

miR‑647 and miR‑1914 promote cancer progression equivalently by downregulating nuclear factor IX in colorectal cancer

MicroRNAs (miRNAs/miRs) have been investigated as diagnostic and prognostic biomarkers for cancer; however, the significance of miRNAs in colorectal cancer (CRC) remains to be elucidated. The aim of the present study was to determine the genetic profiles of CRC tissue, and screen for miRNAs implicated in CRC cell proliferation and migration. RNA sequencing of 10 paired specimens was performed to for screen genes that were upregulated or downregulated in CRC. miRNA expression in CRC specimens and cell lines was confirmed using qPCR analysis. The significance of indicated miRNAs in CRC cell proliferation and migration was evaluated using MTT and scratch wound-healing assays. Online computational prediction, isobaric tags for relative and absolute quantification analysis and a luciferase reporter assay were applied to determine candidate targeted genes for the miRNAs. RNA-seq data revealed miR-1914 as the most prominent miRNA in CRC specimens. qPCR analysis also suggested that the expression of miR-1914, as well as its counterpart miR-647 were elevated in CRC specimens and cell lines. Suppression of miR-647/1914 using small interfering RNAs inhibited CRC SW480 and SW620 cell proliferation, and migration. Nuclear factor I/X (NFIX) was demonstrated to be a candidate for miR-647/1914 and mediated the oncogenic activity of miR-647/1914. In all, miR-647 and miR-1914 were demonstrated to promote the proliferation and migration of CRC cells by directly targeting NFIX. Therapeutic delivery of siRNAs targeting miR-647/1914 and overexpression of NFIX may be feasible approaches for CRC treatment.