The tumour-suppressive function of miR-1 and miR-133a targeting TAGLN2 in bladder cancer

Tumor suppressor miR-1 restrains epithelial-mesenchymal transition and metastasis of colorectal carcinoma via the MAPK and PI3K/AKT pathway

Aberrant expression of miR-1 has been implicated in various cancers. However, the mechanisms underlying the role of miR-1 in CRC progression still have not been clarified clearly. Here, we showed the decreased expression of miR-1 in colorectal carcinoma (CRC) tissues and cell lines. Ectopic introduction of miR-1 suppressed cell proliferation and migration, whereas miR-1 inhibitor performed contrary functions in CRC cells. Stable overexpression of miR-1 was sufficient to inhibit tumor growth and homing capacity in vivo. Proteomic analysis revealed that miR-1 modulated the expression of key cellular molecules and involved in the MAPK and PI3K/AKT pathways by inhibiting phosphorylation of ERK and AKT. Meanwhile, miR-1 also reversed epithelial–mesenchymal transition (EMT), which played a pivotal role in the initiation of metastasis. Further studies found that miR-1 can target the 3' untranslated region (3'UTR) of LIM and SH3 protein 1 (LASP1) mRNA and suppress the expression of LASP1, identified as a CRC-associated protein. In contrast to the phenotypes induced by miR-1 restoration, LASP1-induced cell proliferation and migration partly rescued miR-1-mediated biological behaviors. Our results illustrated that miR-1 play a critical role in CRC progression, which suggests its potential role in the molecular therapy of cancer.

Decreased expression of miR-133a correlates with poor prognosis in colorectal cancer patients

AIM: To investigate microRNA-133a (miR-133a) expression in colorectal cancer (CRC) and its relationship with tumorigenesis and disease prognosis.

METHODS: Quantitative real-time polymerase chain reaction was used to measure levels of miR-133a in tumor samples and adjacent non-cancerous tissues from 169 patients undergoing radical resection for CRC. The associations between miR-133a expression and patient age, sex, as well as clinicopathologic parameters, such as tumor size, differentiation, location, invasion depth, metastasis, tumor-node-metastasis (TNM) stage and overall patient survival, were analyzed by Mann-Whitney U and Kruskal-Wallis tests. The Kaplan-Meier method and Cox proportional hazards regression analyses were performed to estimate the prognostic factors for patient survival prediction.

RESULTS: The expression of miR-133a was significantly downregulated in CRC tissues compared with adjacent non-cancerous tissues (P < 0.05). This reduction was associated with the depth of the local invasion, poor differentiation, lymph node metastasis and advanced disease (P < 0.05). Moreover, Kaplan-Meier analysis demonstrated that patients with low miR-133a expression had poorer overall survival (OS) than those with high miR-133a expression (P < 0.001). Univariate analysis revealed statistically significant correlations between OS and miR-133a level, tumor local invasion, lymph node metastasis and TNM stage (P < 0.001). Furthermore, miR-133a levels and TNM stage were independently associated with OS (HR = 0.590, 95%CI: 0.350-0.995, P < 0.05; and HR = 6.111, 95%CI: 1.029-36.278, P < 0.05, respectively).

CONCLUSION: The downregulation of miR-133a may play an important role in the progression of CRC and can be used as an independent factor to determine CRC prognosis.

Role of microRNAs in malignant mesothelioma

Malignant mesothelioma (MM) is an aggressive tumor, mainly derived from the pleura, which is predominantly associated with exposure to asbestos fibers. The prognosis of MM patients is particularly severe, with a median survival of approximately 9-12 months and latency between exposure and diagnosis ranging from 20-50 years (median 30 years). Emerging evidence has demonstrated that tumor aggressiveness is associated with genome and gene expression abnormalities; therefore, several studies have recently focused on the role of microRNAs (miRNAs) in MM tumorigenesis. miRNAs are small non-protein coding single-stranded RNAs (17-22 nucleotides) involved in numerous cellular processes that negatively regulate gene expression by modulating the expression of downstream target genes. miRNAs are often deregulated in cancer; in particular, the differential miRNA expression profiles of MM cells compared to unaffected mesothelial cells have suggested potential roles of miRNAs as either oncogenes or tumor suppressor genes in MM oncogenesis. In this review, the mechanism of MM carcinogenesis was evaluated through the analysis of the published miRNA expression data. The roles of miRNAs as diagnostic biomarkers and prognostic factors for potential therapeutic strategies will be presented and discussed.

Cell-free urinary microRNA-99a and microRNA-125b are diagnostic markers for the non-invasive screening of bladder cancer

Background

Evidence implicated the diagnostic significance of microRNAs in whole urine/urine sediments in urothelial carcinoma of the bladder (UCB). However, the contaminated blood cells in patients with haematouria significantly altered the expression profiles of urinary microRNA, influencing the test accuracy.

Methods

MicroRNA profiles of the urine supernatants of UCB patients and controls without any malignancy and profiles of malignant and corresponding normal mucosa tissues from the patients were determined by microRNA microarray and compared to identify differentially expressed microRNAs. The differential expression was verified in the tissues of an independent patient cohort by RT-qPCR. The diagnostic significance of selected microRNAs as biomarkers in the urine supernatant was investigated in the expanded cohorts.

Results

MicroRNA-99a and microRNA-125b were down-regulated in the urine supernatants of UCB patients. The degree of down-regulation was associated with the tumor grade. A diagnostic model was developed using a combined index of the levels of microRNA-99a and microRNA-125b in the urine supernatant with a sensitivity of 86.7%, a specificity of 81.1% and a positive predicted value (PPV) of 91.8%. Discriminating between high- and low-grade UCB, the model using the level of microRNA-125b alone exhibited a sensitivity of 81.4%, a specificity of 87.0% and a PPV of 93.4%.

Conclusions

The results revealed a unique microRNA expression signature in the urine supernatants of UCB patients for the development of molecular diagnostic tests. An effective cell-free urinary microRNA-based model was developed using a combined index of the levels of microRNA-99a and microRNA-125b to detect UCB with good discriminating power, high sensitivity and high specificity.

Tumour-suppressive microRNA-24-1 inhibits cancer cell proliferation through targeting FOXM1 in bladder cancer

Here, we found that microRNA-24-1 (miR-24-1) is significantly reduced in bladder cancer (BC) tissues, suggesting that it functions as a tumour suppressor. Restoration of mature miR-24-1 inhibits cancer cell proliferation and induces apoptosis. Forkhead box protein M1 (FOXM1) is a direct target gene of miR-24-1, as shown by genome-wide gene expression analysis and luciferase reporter assay. Overexpressed FOXM1 is confirmed in BC clinical specimens, and silencing of FOXM1 induces apoptosis in cancer cell lines. Our data demonstrate that the miR-24-1-FOXM1 axis contributes to cancer cell proliferation in BC, and elucidation of downstream signalling will provide new insights into the molecular mechanisms of BC oncogenesis.

MicroRNA-145 directly targets the insulin-like growth factor receptor I in human bladder cancer cells

The insulin-like growth factor receptor I (IGF-IR) is a proto-oncogene with potent mitogenic and antiapoptotic activities. It has been reported that expression of IGF-IR is up-regulated in bladder cancer. Here, we assessed whether microRNA-145 (miR-145) regulates IGF-IR expression in bladder cancer. In our study, miR-145 was shown to directly target IGF-IR 3'-untranslated region (UTR) in human bladder cancer cells. Small interfering RNA (siRNA)- and miR-145-mediated IGF-IR knockdown experiments revealed that miR-145 promotes cell apoptosis, and suppresses cell proliferation and migration through suppression of IGF-IR expression. Taken together, our data suggest that miR-145 may inhibit bladder cancer initiation by affecting IGF-IR signaling.

Towards a molecular basis of oligometastatic disease: potential role of micro-RNAs

Oligometastasis is a cancer disease state characterized by a limited number of metastatic tumors involving single or few organs and with biological properties that make them potentially amenable to locoregional antitumor therapy. Current clinical data show that they are potentially curable with surgical resection or/and radiotherapy. Yet, mechanisms of progression from primary tumor to oligometastasis, rather than to polymetastases, is lacking in detail. In the current review we focus on the role of micro-RNAs in the regulation of metastases development and the role they may play in the differentiation of oligometastatic from polymetastatic progression. We also discuss the analyses of metastatic samples from oligo-and polymetastatic patients, which suggest that oligometastasis is a distinct biologic entity regulated in part by micro-RNAs. In addition, a review of the known functions of oligometastatic-specific micro-RNAs suggest that they regulate multiple steps in the metastatic cascade, including epithelial–mesenchymal transition, tumor invasion, intravasation, distant vascular extravasation and proliferation in a distant organ. Understanding the role of micro-RNAs and their target genes in oligometastatic disease may allow for the development of targeted therapies to effectively conrol the spread of metastases.

Tumor-suppressive microRNA-218 inhibits cancer cell migration and invasion via targeting of LASP1 in prostate cancer

Our recent studies of the microRNA (miRNA) expression signature in prostate cancer (PCa) indicated that miRNA-218 (miR-218) was significantly downregulated in clinical specimens, suggesting that miR-218 might act as a tumor-suppressive miRNA in PCa. The aim of the present study was to investigate the functional significance of miR-218 in PCa and to identify novel miR-218-regulated cancer pathways and target genes involved in PCa oncogenesis and metastasis. Restoration of miR-218 in PCa cell lines (PC3 and DU145) revealed that this miRNA significantly inhibited cancer cell migration and invasion. Gene expression data and in silico analysis demonstrated that LIM and SH3 protein 1 (LASP1) is a potential target of miR-218 regulation. LASP1 is a cytoskeletal scaffold protein that plays critical roles in cytoskeletal organization and cell migration. Luciferase reporter assays showed that miR-218 directly regulated expression of LASP1. Moreover, downregulating the LASP1 gene significantly inhibited cell migration and invasion in cancer cells, and the expression of LASP1 was upregulated in cancer tissues. We conclude that loss of tumor-suppressive miR-218 enhanced cancer cell migration and invasion in PCa through direct regulation of LASP1. Our data on pathways regulated by tumor-suppressive miR-218 provide new insight into the potential mechanisms of PCa oncogenesis and metastasis.

Identification of tumour suppressive microRNA-451a in hypopharyngeal squamous cell carcinoma based on microRNA expression signature

Background:

Hypopharyngeal squamous cell carcinoma (HSCC) has a very poor prognosis because of its high rates of regional and distant metastasis. Identification of differentially expressed miRNAs and their regulated molecular targets in tumour cells might enhance our understanding of the molecular mechanisms of metastasis in human cancers.

Methods:

A HSCC miRNA signature was constructed by array-based methods. Functional studies of microRNA-451a (miR-451a) and target genes were performed to investigate cell proliferation, migration and invasion by cancer cell lines. To identify miR-451a-regulated molecular targets, we adopted gene expression analysis and in silico database analysis.

Results:

Our miRNA signature revealed that miR-451a was significantly downregulated in HSCC. Restoration of miR-451a in cancer cell lines revealed that this miRNA significantly inhibited cancer cell migration and invasion. Our data demonstrated that the gene coding for endothelial and smooth muscle cell-derived neuropilin-like molecule (ESDN/DCBLD2) was a direct target of miR-451a regulation. Silencing of ESDN inhibited cell migration and invasion by cancer cells.

Conclusions:

Loss of tumour suppressive miR-451a enhanced cancer cell migration and invasion in HSCC through direct regulation of ESDN. Our miRNA signature and functional analysis of targets regulated by tumour suppressive miR-451a provide new insights into the potential mechanisms of HSCC oncogenesis and metastasis.

miRNA panels as biomarkers for bladder cancer

Aim: Specific miRNA profiles have been identified for several samples from patients with bladder cancer. The results are not always congruent and partly contradictory. A comparison of published data was performed to select potential markers. Materials & methods: A literature search in PubMed identified 79 articles published prior to June 2013. Reports regarding the detection of miRNAs in urine and blood have rarely been published; to date, nine respectively three articles are available. Results: The comparison of published data proved the utility of miRNAs as diagnostic and prognostic indicators of bladder cancer. In urine samples from bladder cancer patients, seven miRNAs were concordantly expressed with tumor tissues. Conclusion: Standardization is strictly required in pre-analytics and methods of miRNA measurements.

Role of microRNA-1 in human cancer and its therapeutic potentials

While the mechanisms of human cancer development are not fully understood, evidence of microRNA (miRNA, miR) dysregulation has been reported in many human diseases, including cancer. miRs are small noncoding RNA molecules that regulate posttranscriptional gene expression by binding to complementary sequences in the specific region of gene mRNAs, resulting in downregulation of gene expression. Not only are certain miRs consistently dysregulated across many cancers, but they also play critical roles in many aspects of cell growth, proliferation, metastasis, apoptosis, and drug resistance. Recent studies from our group and others revealed that miR-1 is frequently downregulated in various types of cancer. Through targeting multiple oncogenes and oncogenic pathways, miR-1 has been demonstrated to be a tumor suppressor gene that represses cancer cell proliferation and metastasis and promotes apoptosis by ectopic expression. In this review, we highlight recent findings on the aberrant expression and functional significance of miR-1 in human cancers and emphasize its significant values for therapeutic potentials.

MicroRNA-126 inhibits invasion in bladder cancer via regulation of ADAM9

Background:

The miRNA deregulation is commonly observed in human malignancies, where they act as tumour suppressors or oncogenes. Despite the association of several miRNAs with bladder cancer, little is known about the miRNAs that contribute to bladder cancer progression from non-muscle invasive (NMI) to muscle-invasive (MI) disease.

Methods:

We first profiled the expression of miRNAs and mRNAs in a cohort of urothelial carcinomas and further characterised the role of miR-126 in invasion, as it emerged as the most downregulated miRNA between MI and NMI tumours.

Results:

We found that restoration of miR-126 levels attenuated the invasive potential of bladder cancer cells. Mechanistically, we identified the role of miR-126 in invasion through its ability to target ADAM9. Notably, a significant inverse correlation between miR-126 and ADAM9 expression was observed, where ADAM9 was upregulated in MI bladder cancer cells. While knockdown of ADAM9 attenuated the invasiveness of cells with low miR-126 levels, experimental upregulation of ADAM9 recapitulated the invasive phenotype. Furthermore, ADAM9 expression assessed by immunohistochemistry significantly correlated with poor prognosis in patients with urothelial carcinoma.

Conclusions:

In this study we describe the role of miR-126 in bladder cancer progression, identifying miR-126 and ADAM9 as potential clinical biomarkers of disease aggressiveness.

MicroRNA-206 suppresses gastric cancer cell growth and metastasis

Gastric cancer is one of the leading causes of cancer death world-wide and carries a high rate of metastatic risk. In addition to other protein-coding oncogenes and tumor suppressor genes, microRNAs play an important role in gastric cancer tumorigenic progression. Here, we show that miR-206 is expressed at markedly low levels in a cohort of gastric tumors compared to their matching normal tissues, and in a number of gastric cancer cell lines. Down-regulation of miR-206 was particularly significant in tumors with lymphatic metastasis, local invasion, and advanced TNM staging. We find that forced expression of miR-206 suppressed the proliferation, colony-formation, and xenograft tumorigenesis of SCG-7901 cells, a line of gastric cancer cells. Forced expression of miR-206 also suppressed SCG-7901 cell migration and invasion, as well as metastasis in cell culture or tail-vein injected mouse models, respectively. The anti-metastatic effect of miR-206 is likely mediated by targeting metastasis regulatory genes STC2, HDAC4, KLF4, IGF1R, FRS2, SFRP1, BCL2, BDNF, and K-ras, which were drastically down-regulated by stable expression of exogenous miR-206 in SCG-7901 cells. Taken together, our results indicate that miR-206 is a tumor suppressor of gastric cancer acting at steps that regulate metastasis.

MicroRNA profiling of rats with ochratoxin A nephrotoxicity

Background

Nephrotoxicity is the most prominent one among the various toxicities of ochratoxin A (OTA). MicroRNAs (miRNAs) are small non-coding RNAs that have an impact on a wide range of biological processes by regulating gene expression at post-transcriptional level or protein systhesis level. The objective of this study is to analyze miRNA profiling in the kidneys of rats gavaged with OTA.

Results

To profile miRNAs in the kidneys of rats with OTA nephrotoxicity, high-throughput sequencing and bioinformatics approaches were applied to analyze the miRNAs in the kidney of rats following OTA treatment. A total of 409 known miRNAs and 8 novel miRNAs were identified in the kidney and the levels of the novel miRNAs were varied in response to different doses of OTA. Expression of miR-129, miR-130a, miR-130b, miR-141, miR-218b and miR-3588 were uniquely suppressed in mid dose but then elevated in high dose, with opposite expression to their target genes. The expression pattern was closely related with the “MAPK signaling pathway”. Dicer1 and Drosha were significantly suppressed, indicating an impairment of miRNA biogenesis in response to OTA.

Conclusions

The abrogation of miRNA maturation process suggests a new target of OTA toxicity. Moreover, the identification of the differentially expressed miRNAs provides us a molecular insight into the nephrtoxicity of OTA.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-333) contains supplementary material, which is available to authorized users.

miR-1 and miR-145 act as tumor suppressor microRNAs in gallbladder cancer

The development of miRNA-based therapeutics represents a new strategy in cancer treatment. The objectives of this study were to evaluate the differential expression of microRNAs in gallbladder cancer (GBC) and to assess the functional role of miR-1 and miR-145 in GBC cell behavior. A profile of miRNA expression was determined using DharmaconTM microarray technology. Differential expression of five microRNAs was validated by TaqMan reverse transcription quantitative-PCR in a separate cohort of 8 tumors and 3 non-cancerous samples. Then, we explored the functional role of miR-1 and miR-145 in tumor cell behavior by ectopic in vitro expression in the GBC NOZ cell line. Several miRNAs were found to be aberrantly expressed in GBC; most of these showed a significantly decreased expression compared to non-neoplastic tissues (Q value<0.05). The differential expression of 7 selected miRNAs was confirmed by real time PCR. Pathway enrichment analysis revealed that the most deregulated miRNAs (miR-1, miR-133, miR-143 and miR-145) collectively targeted a number of genes belonging to signaling pathways such as TGF-β, ErbB3, WNT and VEGF, and those regulating cell motility or adhesion. The ectopic expression of miR-1 and miR-145 in NOZ cells significantly inhibited cell viability and colony formation (P<0.01) and reduced gene expression of VEGF-A and AXL. This study represents the first investigation of the miRNA expression profile in gallbladder cancer, and our findings showed that several miRNAs are deregulated in this neoplasm. In vitro functional assays suggest that miR-1 and miR-145 act as tumor suppressor microRNAs in GBC.

The microRNA expression signature of bladder cancer by deep sequencing: the functional significance of the miR-195/497 cluster

Current genome-wide microRNA (miRNA) expression signature analysis using deep sequencing technologies can drive the discovery of novel cancer pathways regulated by oncogenic and/or tumor suppressive miRNAs. We determined the genome-wide miRNA expression signature in bladder cancer (BC) by deep sequencing technology. A total of ten small RNA libraries were sequenced (five BCs and five samples of histologically normal bladder epithelia (NBE)), and 13,190,619 to 18,559,060 clean small RNA reads were obtained. A total of 933 known miRNAs and 17 new miRNA candidates were detected in this analysis. Among the known miRNAs, a total of 60 miRNAs were significantly downregulated in BC compared with NBE. We also found that several miRNAs, such as miR-1/133a, miR-206/133b, let-7c/miR-99a, miR-143/145 and miR-195/497, were located close together at five distinct loci and constituted clustered miRNAs. Among these clustered miRNAs, we focused on the miR-195/497 cluster because this clustered miRNA had not been analyzed in BC. Transfection of mature miR-195 or miR-497 in two BC cell lines (BOY and T24) significantly inhibited cancer cell proliferation, migration and invasion, suggesting that the miR-195/497 cluster functioned as tumor suppressors in BC. Regarding the genes targeted by the miR-195/497 cluster, the TargetScan algorithm showed that 6,730 genes were putative miR-195/497 targets, and 113 significantly enriched signaling pathways were identified in this analysis. The “Pathways in cancer” category was the most enriched, involving 104 candidate target genes. Gene expression data revealed that 27 of 104 candidate target genes were actually upregulated in BC clinical specimens. Luciferase reporter assays and Western blotting demonstrated that BIRC5 and WNT7A were directly targeted by miR-195/497. In conclusion, aberrant expression of clustered miRNAs was identified by deep sequencing, and downregulation of miR-195/497 contributed to BC progression and metastasis. Tumor suppressive miRNA-mediated cancer pathways provide new insights into the potential mechanisms of BC oncogenesis.

Proteomic analysis of the proteins that are associated with the resistance to paclitaxel in human breast cancer cells

Cancers frequently develop resistance to paclitaxel but the underlying molecular mechanisms remain to be determined. We have investigated the proteins that are associated with the paclitaxel resistance in human breast cancer MCF-7 cells using proteomic analysis. Paclitaxel resistant human breast cancer MCF-7 cells (MCF-7/P) were established by escalating the concentrations of paclitaxel to drug-sensitive MCF-7 cells (MCF-7/S). The global protein profiles of MCF-7/P and MCF-7/S were compared using two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Eleven proteins were upregulated while six proteins were downregulated in MCF-7/P cells. Western blot and real-time PCR analyses showed that the protein and mRNA levels of heterogeneous nuclear ribonucleoprotein (hnRNP C1/C2), SET nuclear oncogene (SET), aspartate aminotransferase (AAT), transgelin-2 (TAGLN2) were increased, while those of nucleoside-diphosphate kinase A (NDKA) were decreased in MCF-7/P cells. Accordingly, knockdown of TAGLN2 by siRNA sensitized MCF-7/P cells to paclitaxel and reduced the multidrug resistance (MDR). Our identification of differential proteins, particularly transgelin-2, provides new insights into the mechanism of MDR to paclitaxel and novel biological targets for breast cancer treatment.

Role of microRNA-133a in epithelial ovarian cancer pathogenesis and progression

It has been demonstrated that microRNA (miR)-133a is downregulated in a number of human malignancies and is closely associated with the progression of tumors. The present study was conducted to investigate the contribution of miR-133a to the initiation and malignant progression of human epithelial ovarian cancer (EOC). Quantitative polymerase chain reaction was employed to detect the expression of miR-133a in the human EOC OVCAR-3 cell line, normal human ovarian surface epithelial (tsT) cells and 96 tissue samples, including 70 EOC tissues and 26 normal ovarian tissue sections. Additionally, analysis of the correlation between miR-133a levels and clinicopathological characteristics was carried out. The effect of miR-133a on cell viability, apoptosis, invasion and migration was investigated following transfection with miR-133a mimics and negative control small interfering RNA in OVCAR-3 cells. Marked downregulation of miR-133a was observed in the OVCAR-3 cell line and primary tumor samples, and it was found that reduced miR-133a expression significantly correlated with advanced clinical stages, poor histological differentiation and lymph node metastasis. Furthermore, OVCAR-3 cell viability, invasion and migration were significantly inhibited, while cell apoptosis was increased, following transfection of miR-133a mimics. The present study reveals the critical role that miR-133a plays in EOC pathogenesis and development, indicating that it may act as a promising biomarker for predicting EOC progression and as a potential target for gene therapy.

Transgelins, cytoskeletal proteins implicated in different aspects of cancer development

Transgelin is an abundant protein of smooth muscle cells, where its role has been primarily studied. As a protein affecting dynamics of the actin cytoskeleton via stabilization of actin filaments, transgelin is both directly and indirectly involved in many cancer-related processes such as migration, proliferation, differentiation or apoptosis. Transgelin was previously reviewed as a tumor suppressor; however, recent data based on a number of proteomics studies indicate its pro-tumorigenic role, for example, in colorectal or hepatocellular cancer. We summarize these contradictory observations in both clinical and functional proteomics projects and analyze the role of transgelin in tumors in detail. Generally, the expression and biological role of transgelin seem to differ among various types of tumor cells and stroma, and possibly change during tumor progression. We also overview the recent data on transgelin-2, a sequence homolog of transgelin, whose role in the tumor development might be contradictory to the role of transgelin.

miR-1 induces growth arrest and apoptosis in malignant mesothelioma

BACKGROUND

We investigated microRNA expression profiles of malignant pleural mesothelioma (MPM) specimens to identify novel microRNA that are potentially involved in the oncogenic transformation of human pleural cells.

METHODS

microRNA microarray transcriptional profiling studies of 25 MPM primary tumors were performed. We used normal pleural tissue from an unmatched patient cohort as normal comparators. To confirm microarray data, we used real-time quantitative polymerase chain reaction. Representative cell lines H513 and H2052 were used in functional analyses of miR-1.

RESULTS

In addition to several novel MPM-associated microRNAs, we observed that the expression level of miR-1 was significantly lower in tumors as compared with normal pleural specimens. Subsequently, pre-miR of miR-1 was introduced into MPM cell lines to overexpress this microRNA. Phenotypic changes of these altered cells were assayed. The cellular proliferation rate was significantly inhibited after overexpression of miR-1. Early and late apoptosis was increased markedly in miR-1-transfected cell lines. Taken together, these data suggested that overexpression of miR-1 induced apoptosis in these MPM cell lines, acting as a tumor suppressor. We confirmed our observations by assessing in the transduced MPM cells cell cycle-related, proapoptotic, and antiapoptotic genes, which all showed coordinated, significant changes characteristic of the apoptotic phenotype.

CONCLUSIONS

Further investigation and validation of our microRNA database of MPM may elucidate previously unrecognized molecular pathways and/or mechanisms by identifying novel microRNAs that are involved in malignant transformation. Our study has now found miR-1 to be one of these MPM-associated microRNAs, with potential pathogenic and therapeutic significance.

MiR-133b is down-regulated in human osteosarcoma and inhibits osteosarcoma cells proliferation, migration and invasion, and promotes apoptosis

MicroRNAs (miRNAs) decrease the expression of specific target oncogenes or tumor suppressor genes and thereby play crucial roles in tumorigenesis and tumor growth. To date, the potential miRNAs regulating osteosarcoma growth and progression are not fully identified yet. In this study, the miRNA microarray assay and hierarchical clustering analysis were performed in human osteosarcoma samples. In comparison with normal human skeletal muscle, 43 miRNAs were significantly differentially expressed in human osteosarcomas (fold change ≥2 and p≤0.05). Among these miRNAs, miR-133a and miR-133b expression was decreased by 135 folds and 47 folds respectively and the decreased expression was confirmed in both frozen and paraffin-embedded osteosarcoma samples. The miR-133b precursor expression vector was then transfected into osteosarcoma cell lines U2-OS and MG-63, and the stable transfectants were selected by puromycin. We found that stable over-expression of miR-133b in osteosarcoma cell lines U2-OS and MG-63 inhibited cell proliferation, invasion and migration, and induced apoptosis. Further, over-expression of miR-133b decreased the expression of predicted target genes BCL2L2, MCL-1, IGF1R and MET, as well as the expression of phospho-Akt and FAK. This study provides a new insight into miRNAs dysregulation in osteosarcoma, and indicates that miR-133b may play as a tumor suppressor gene in osteosarcoma.

Perturbation of MicroRNA-370/Lin-28 homolog A/nuclear factor kappa B regulatory circuit contributes to the development of hepatocellular carcinoma

MicroRNA 370 (miR-370) is located within the DLK1/DIO3 imprinting region on human chromosome 14, which has been identified as a cancer-associated genomic region. However, the role of miR-370 in malignances remains controversial. Here, we report that miR-370 was repressed in human hepatocellular carcinoma (HCC) tissues and hepatoma cell lines. Using gain-of-function and loss-of-function experiments, we demonstrated that miR-370 inhibited the malignant phenotype of HCC cells in vitro. Overexpression of miR-370 inhibited growth and metastasis of HCC cells in vivo. Moreover, the RNA-binding protein, LIN28A, was identified as a direct functional target of miR-370, which, in turn, blocked the biogenesis of miR-370 by binding to its precursor. LIN28A also mediated the suppressive effects of miR-370 on migration and invasion of HCC cells by post-transcriptionally regulating RelA/p65, which is an important effector of the canonical nuclear factor kappa B (NF-κB) pathway. Interleukin-6 (IL-6), a well-known NF-κB downstream inflammatory molecule, reduced miR-370 but increased LIN28A levels in HCC. Furthermore, miR-370 levels were inversely correlated with LIN28A and IL-6 messenger RNA (mRNA) levels, whereas LIN28A mRNA expression was positively correlated with IL-6 expression in human HCC samples. Interestingly, reduction of miR-370 expression was associated with the development of HCC in rats, as well as with aggressive tumor behavior and short survival in HCC patients.

CONCLUSIONS

These data demonstrate the involvement of a novel regulatory circuit consisting of miR-370, LIN28A, RelA/p65 and IL-6 in HCC progression. Manipulating this feedback loop may have beneficial effect in HCC treatment.

The tumor-suppressive microRNA-143/145 cluster inhibits cell migration and invasion by targeting GOLM1 in prostate cancer

Our recent study of microRNA (miRNA) expression signature of prostate cancer (PCa) has revealed that the microRNA-143/145 (miR-143/145) cluster is significantly downregulated in cancer tissues, suggesting that these cluster miRNAs are candidate tumor suppressors. The aim of this study was to investigate the functional significance of the miR-143/145 cluster in PCa cells and to identify novel targets regulated by these cluster miRNAs in PCa. Restoration of miR-143 or miR-145 in PCa cell lines (PC3 and DU145) revealed that these miRNAs significantly inhibited cancer cell migration and invasion. Gene expression data and in silico analysis demonstrated that Golgi membrane protein 1 (GOLM1) resembling a type II golgi transmembrane protein was a potential target of miR-143/145 cluster target gene. Gene expression studies and luciferase reporter assays showed that GOLM1 was directly regulated by the miR-143/145 cluster. Silencing of GOLM1 resulted in significant inhibition of cell migration and invasion in PCa cells. Furthermore, the expression of GOLM1 was upregulated in cancer tissues by immunohistochemistry. Loss of the tumor-suppressive miR-143/145 cluster enhanced cancer cell migration and invasion in PCa through directly regulating GOLM1. Our data on target genes regulated by the tumor-suppressive miR-143/145 cluster provide new insights into the potential mechanisms of PCa oncogenesis and metastasis.

Hsa-miR-125b suppresses bladder cancer development by down-regulating oncogene SIRT7 and oncogenic long noncoding RNA MALAT1

MicroRNAs mainly inhibit coding genes and long non-coding RNA expression. Here, we report that hsa-miR-125b and oncogene SIRT7/ oncogenic long noncoding RNA MALAT1 were inversely expressed in bladder cancer. Hsa-miR-125b mimic downregulated, whereas hsa-miR-125b inhibitor upregulated the expression of SIRT7 and MALAT1. Binding sites were confirmed between hsa-miR-125b and SIRT7/MALAT1. Upregulation of hsa-miR-125b or downregulation of SIRT7 inhibited proliferation, motility and increased apoptosis. The effects of upregulation of hsa-miR-125b were similar to that of silencing MALAT1 in bladder cancer as we had previously described. These data suggest that hsa-miR-125b suppresses bladder cancer development via inhibiting SIRT7 and MALAT1.

Tumor-suppressive function of miR-139-5p in esophageal squamous cell carcinoma

Recent studies have demonstrated the possible function of miR-139-5p in tumorigenesis. However, the exact mechanism of miR-139-5p in cancer remains unclear. In this study, the association of miR-139-5p expression with esophageal squamous cell carcinoma (ESCC) was evaluated in 106 pairs of esophageal cancer and adjacent non-cancerous tissue from ESCC patients. The tumor suppressive features of miR-139-5p were measured by evaluating cell proliferation and cell cycle state, migratory activity and invasion capability, as well as apoptosis. Luciferase reporter assay and Western blot analysis were performed to determine the target gene regulated by miR-139-5p. The mRNA level of NR5A2, the target gene of miR-139-5p, was determined in ESCC patients. Results showed that reduced miR-139-5p level was associated with lymph node metastases of ESCC. MiR-139-5p was investigated to induce cell cycle arrest in the G0/G1 phase and to suppress the invasive capability of esophageal carcinoma cells by targeting the 3′UTR of oncogenic NR5A2. Cyclin E1 and MMP9 were confirmed to participate in cell cycle arrest and invasive suppression induced by NR5A2, respectively. Pearson correlation analysis further confirmed the significantly negative correlation between miR-139-5p and NR5A2 expression. The results suggest that miR-139-5p exerts a growth- and invasiveness-suppressing function in human ESCCs, which demonstrates that miR-139-5p is a potential biomarker for early diagnosis and prognosis and is a therapeutic target for ESCC.

Tumor-suppressive microRNA-143/145 cluster targets hexokinase-2 in renal cell carcinoma

Our recent studies of microRNA (miRNA) expression signatures have indicated that the miR-143/145 cluster is significantly downregulated in several types of cancer and represents a putative tumor-suppressive miRNA in human cancers. The aim of this study was to investigate the functional significance of the miR-143/145 cluster in cancer cells and to identify novel molecular targets of the miR-143/145 cluster in renal cell carcinoma (RCC). The expression levels of miR-143 and miR-145 were significantly downregulated in RCC tissues compared with adjacent non-cancerous tissues. A significant positive correlation was recognized between miR-143 and miR-145 expression. Restoration of mature miR-143 or miR-145 in 786-O and A498 RCC cells revealed that both mature miRNAs significantly inhibited cancer cell proliferation and invasion, suggesting that the miR-143/145 cluster functioned as a tumor suppressor in RCC. Gene expression data and in silico database analysis showed that the hexokinase-2 (HK2) gene, which encodes a glycolytic enzyme crucial for the Warburg effect in cancer cells, was a candidate target of the miR-143/145 cluster. Luciferase reporter assays showed that both miR-143 and miR-145 directly regulated HK2. In RCC clinical specimens, the expression of HK2 was significantly higher in cancer tissues than in non-cancerous tissues. Silencing HK2 suppressed RCC cell proliferation and invasion, suggesting that HK2 has oncogenic functions in RCC. Thus, our data showed that loss of the tumor-suppressive miR-143/145 cluster enhanced RCC cell proliferation and invasion through targeting HK2.

MicroRNA-133a, downregulated in osteosarcoma, suppresses proliferation and promotes apoptosis by targeting Bcl-xL and Mcl-1

Deregulated microRNAs and their roles in cancer development have attracted much attention. Although miR-133a has been shown to be important in osteogenesis, its roles in osteosarcoma carcinogenesis and progression remain unknown. Hence, we focused on the expression and mechanisms of miR-133a in osteosarcoma development in this study. We found that miR-133a was downregulated in osteosarcoma cell lines and primary human osteosarcoma tissues, and its decrease was significantly correlated with tumor progression and prognosis of the patients. Functional studies revealed that restoration of miR-133a could reduce cell proliferation, promote cell apoptosis, and suppress tumorigenicity in osteosarcoma cell lines. Furthermore, bioinformatic prediction and experimental validation were applied to identify target genes of miR-133a, and the results revealed that the anti-tumor effect of miR-133a was probably due to targeting and repressing of Bcl-xL and Mcl-1 expression. Taken together, our data elucidate the roles of miR-133a in osteosarcoma pathogenesis and implicate its potential in cancer therapy.

miR-133a represses tumour growth and metastasis in colorectal cancer by targeting LIM and SH3 protein 1 and inhibiting the MAPK pathway

In recent studies of microRNA expression, miR-133a deregulation was identified in colorectal carcinoma (CRC). However, the mechanisms underlying the pathogenesis and progression of CRC are poorly understood. We found that miR-133a expression was usually down-regulated in CRC cell lines and tissue specimens. Ectopic miR-133a expression inhibited cell proliferation and cell migration. Stable overexpression of miR-133a was sufficient to suppress tumour growth and intrahepatic and pulmonary metastasis in vivo. Additional studies showed that miR-133a can target the 3' untranslated region (3'UTR) of LIM and SH3 protein 1 (LASP1) mRNA and suppress the expression of LASP1, which we identified in previous studies as a CRC-associated protein. In contrast to the phenotypes induced by miR-133a restoration, LASP1-induced cell proliferation and migration rescued miR-133a-mediated biological behaviours, as did LASP1 overexpression. Investigations of possible mechanisms underlying these behaviours revealed that miR-133a modulates the expression of key cellular molecules and participates in the MAPK pathway by inhibiting phosphorylation of ERK and MEK. miR-133a may play a key role in CRC genesis and metastasis, which suggests its potential role in the molecular therapy of cancer.

miRNA profiling identifies candidate mirnas for bladder cancer diagnosis and clinical outcome

Bladder cancer is a common cancer in the Western world. The current prognosticators such as tumor grade, stage, size, and multifocality do not accurately reflect the clinical outcome. It is of clinical interest to identify biomarkers that could improve diagnostic and/or prognostic predictions. The objectives of this study were to identify deregulated miRNAs in bladder cancer samples and evaluate their potential as diagnostic and prognostic biomarkers. We screened 723 miRNAs by microarray and selected a subset of 15 distinctively deregulated miRNAs for further validation by real-time quantitative RT-(q)PCR. Seven miRNAs (miR-20a, miR-106b, miR-130b, miR-141, miR-200a, miR-200a*, and miR-205) were found to be up-regulated and eight miRNAs (miR-100, miR-125b, miR-130a, miR-139-5p, miR-145*, miR-199a-3p, miR-214, and miR-222) were found to be down-regulated in malignant bladder tissue samples compared to healthy tissue. Four miRNAs that have already been described in the literature (miR-141, miR-199a-3p, miR-205, and miR-214) were significantly differentially expressed between nonmuscle-invasive and muscle-invasive bladder cancer. Furthermore, real-time RT-qPCR of all miRNAs provided high overall correct classification (>75%) of bladder cancer diagnosis. Two miRNAs (miR-141 and miR-205) were associated with overall survival time. The verification of tumor-specific miRNA expression profile, together with the observed association of miR-141 and miR-205 expression with overall survival, underline the potential of miRNAs to function as diagnostic and/or prognostic markers of bladder cancer.

Alterations of DNA methylome in human bladder cancer

Bladder cancer is the fourth most common cancer in men in the United States, and its recurrence rate is highest among all malignancies. The unmet need for improved strategies for early detection, treatment, and monitoring of the progression of this disease continues to translate into high mortality and morbidity. The quest for advanced diagnostic, therapeutic, and prognostic approaches for bladder cancer is a high priority, which can be achieved by understanding the molecular mechanisms of the initiation and progression of this malignancy. Aberrant DNA methylation in single or multiple cancer-related genes/loci has been found in human bladder tumors and cancer cell lines, and urine sediments, and correlated with many clinicopathological features of this disease, including tumor relapse, muscle-invasiveness, and survival. The present review summarizes the published research on aberrant DNA methylation in connection with human bladder cancer. Representative studies are highlighted to set forth the current state of knowledge, gaps in the knowledgebase, and future directions in this prime epigenetic field of research. Identifying the potentially reversible and 'drugable' aberrant DNA methylation events that initiate and promote bladder cancer development can highlight biological markers for early diagnosis, effective therapy and accurate prognosis of this malignancy.

The evolving understanding of microRNA in bladder cancer

PURPOSE

Micro ribonucleic acid (miR) expression is altered in urologic malignancies, including bladder cancer (BC). Individual miRs have been shown to modulate multiple signaling pathways that contribute to BC. We reviewed the primary literature on the role of miRs in BC; we provide a general introduction to the processing, regulation, and function of miRs as tumor suppressors and oncogenes and critically evaluate the literature on the implications of altered miR expression in BC.

MATERIALS AND METHODS

We searched the English language literature for original and review articles in PubMed from 1993 to March 2013, using the terms "microRNA" and "bladder cancer," "transitional cell carcinoma," or "urothelial carcinoma." This search yielded 133 unique articles with more than 85% of them published within the last 3 years.

RESULTS

To date, the majority of miR studies in BC use profiling to describe dynamic changes in miR expression across stage and grade. Generalized down-regulation of miRs, including those that target the fibroblast growth factor 3 pathway, such as miR-145, miR-101, miR-100, and miR-99a, has been observed in low-grade, non-muscle invasive BC. In contrast, generalized increased expression of miRs is observed in high-grade, muscle-invasive BC compared with adjacent normal bladder urothelium, including miRs predicted to target p53, such as miR-21 and miR-373. Furthermore, p53 suppresses transcriptional factors that promote mesenchymal differentiation, ZEB-1 and ZEB-2, through regulation of the miR200 family.

CONCLUSIONS

Aberrations in miR expression identified between non-muscle invasive BC and muscle-invasive BC provide insight into the molecular alterations known to distinguish the two parallel pathways of bladder carcinogenesis. The heterogeneity of tumor specimens and research methods limits the reproducibility of changes in miR expression profiles between studies and underscores the importance of in vivo validation in a field that utilizes in silico miR target-prediction models.

Identification of microRNAs in blood and urine as tumour markers for the detection of urinary bladder cancer

Since differential expression of microRNAs (miRNAs) has been found to be highly associated with several types of cancer, the goal of the present study was to identify an miRNA fingerprint as a non‑invasive diagnostic tool to detect urinary bladder cancer using the easily accessible samples of whole blood and urine. Blood and urine samples from 4 controls and from patients suffering from superficial and invasive bladder cancer were analyzed using miRNA microarray consisting of 754 human miRNAs from the Sanger database v14. Using RT‑qPCR technique, 6 of the differentially expressed miRNAs were validated in the controls (20 blood, 19 urine samples) and patients with superficial (18 blood, 16 urine samples) or invasive (20 blood and urine samples each) tumours. Three blood miRNAs (miR‑26b‑5p, miR‑144‑5p, miR‑374‑5p) were found to be significantly upregulated in invasive bladder tumour patients (P<0.05) when compared to the control group. The expression of 2 miRNAs (miR‑618, miR‑1255b‑5p) in the urine of patients with invasive tumours was significantly (P<0.05) increased in comparison to the control group. Blood miR‑26b‑5p detected the presence of invasive bladder tumours with 94% specificity and 65% sensitivity. The urine miR‑1255b‑5p reached 68% specificity and 85% sensitivity in the diagnosis of invasive tumours. This pilot study represents the first characterization of an miRNA profile for urinary bladder tumours in whole blood samples. In addition, it was shown that invasive bladder tumours could be identified by differentially expressed urine miRNAs. Further studies are needed to test the clinical usefulness for bladder cancer detection and surveillance.

miR‑133a suppresses cell proliferation, migration and invasion in human lung cancer by targeting MMP‑14

Lung cancer is the leading cause of cancer‑related mortality worldwide. Over half of lung cancer cases are diagnosed after metastasis, for which the median survival time is approximately 8 months. microRNAs (miRNAs), which are a class of single‑stranded endogenous non‑coding RNAs, are likely to be involved in most biological processes. miR‑133 plays roles in cardiac development and disease, and recent studies showed that miR‑133 is downregulated in various human malignancies, such as bladder and lung cancer. However, its detailed role in the processes of cancer remains to be determined. In the present study, we found that in the lung cancer cell lines A549 and NCI‑H1299 overexpression of miR‑133a suppressed cell proliferation, migration and invasion. The miR‑133a‑induced suppression of cell migration and invasion can be reversed by miR‑133a‑specific inhibitor. According to the mRNA sequence, matrix metalloproteinase (MMP)‑14, which is an important regulator of metastasis, is a predicted target of miR‑133a. This was confirmed by dual luciferase reporter assay. Moreover, miR‑133a overexpression decreases the mRNA and protein levels of MMP‑14. Collectively, these results suggest that miR‑133a may inhibit lung cancer metastasis by targeting MMP‑14 and may be used as an anti‑metastatic therapy in lung cancer patients.

Tumor suppressive microRNA-218 inhibits cancer cell migration and invasion by targeting focal adhesion pathways in cervical squamous cell carcinoma

Cervical cancer is one of the most common cancers in women. More than 275,100 women die from cervical cancer each year. Cervical squamous cell carcinoma (cervical SCC), one of the most frequent types of cervical cancers, is associated with high-risk human papilloma virus (HPV), although HPV infection alone may not be enough to induce malignant transformation. MicroRNAs (miRNAs), a class of small non-coding RNAs, regulate protein-coding gene expression by repressing translation or cleaving RNA transcripts in a sequence-specific manner. A growing body of evidence suggests that miRNAs contribute to cervical SCC progression, development and metastasis. miRNA expression signatures in SCC (hypopharyngeal SCC and esophageal SCC) revealed that miR-218 expression was significantly reduced in cancer tissues compared with adjacent non-cancerous epithelium, suggesting that miR-218 is a candidate tumor suppressor. The aim of this study was to investigate the functional significance of miR-218 in cervical SCC and to identify novel miR‑218-mediated cancer pathways in cervical SCC. Restoration of miR-218 significantly inhibited cancer cell migration and invasion in both HPV-positive and HPV-negative cervical SCC cell lines. These data indicated that miR-218 acts as a tumor suppressor in cervical SCC. Our in silico analysis showed that miR-218 appeared to be an important modulator of tumor cell processes through suppression of many targets, particularly those involved in focal adhesion signaling pathways. Gene expression data indicated that LAMB3, a laminin protein known to influence cell differentiation, migration, adhesion, proliferation and survival, was upregulated in cervical SCC clinical specimens, and silencing studies demonstrated that LAMB3 functioned as an oncogene in cervical SCC. The identification of novel tumor-suppressive miR-218-mediated molecular pathways has provided new insights into cervical SCC oncogenesis and metastasis.

Simultaneous miRNA and mRNA transcriptome profiling of human myoblasts reveals a novel set of myogenic differentiation-associated miRNAs and their target genes

Background

miRNA profiling performed in myogenic cells and biopsies from skeletal muscles has previously identified miRNAs involved in myogenesis.

Results

Here, we have performed miRNA transcriptome profiling in human affinity-purified CD56+ myoblasts induced to differentiate in vitro. In total, we have identified 60 miRNAs differentially expressed during myogenic differentiation. Many were not known for being differentially expressed during myogenic differentiation. Of these, 14 (miR-23b, miR-28, miR-98, miR-103, miR-107, miR-193a, miR-210, miR-324-5p, miR-324-3p, miR-331, miR-374, miR-432, miR-502, and miR-660) were upregulated and 6 (miR-31, miR-451, miR-452, miR-565, miR-594 and miR-659) were downregulated. mRNA transcriptome profiling performed in parallel resulted in identification of 6,616 genes differentially expressed during myogenic differentiation.

Conclusions

This simultaneous miRNA/mRNA transcriptome profiling allowed us to predict with high accuracy target genes of myogenesis-related microRNAs and to deduce their functions.

FoxM1 is overexpressed in Helicobacter pylori-induced gastric carcinogenesis and is negatively regulated by miR-370

Helicobacter pylori (H. pylori) infections are strongly implicated in human gastric mucosa-associated diseases. Forkhead box M1 (FoxM1), a key positive regulator of cell proliferation, is overexpressed in gastric cancer. MicroRNAs are important post-transcriptional regulators of gene expression. In this study, the effects of H. pylori infection on FoxM1 expression and possible mechanisms of carcinogenesis were explored. The expression of FoxM1 was gradually increased in human gastric specimens from inflammation to cancer. FoxM1 upregulation was time- and concentration-dependent in gastric epithelial-derived cell lines infected with H. pylori. CagA, a key virulence factor of H. pylori, was associated with increased FoxM1 expression. H. pylori and CagA inhibited the expression of p27(Kip1) (CDKN1B) and promoted cell proliferation by upregulating FoxM1. The expression of miR-370 was decreased in human gastritis and gastric cancer. FoxM1 was directly downregulated by miR-370 in gastric cell lines. H. pylori and CagA inhibited miR-370 expression, which led to overexpression of FoxM1 and cell proliferation. Furthermore, the overexpression of FoxM1 and reduced expression of miR-370 was confirmed in H. pylori-infected C57BL/6J mice. H. pylori infection and CagA upregulated FoxM1 expression, dependent on miR-370, altered the expression of p27(Kip1), and promoted proliferation in gastric cells.

IMPLICATIONS

These findings delineate the mechanisms governing FoxM1 regulation and the role of H. pylori in the process of gastric carcinogenesis.

MicroRNA-218 inhibits cell migration and invasion in renal cell carcinoma through targeting caveolin-2 involved in focal adhesion pathway

PURPOSE

Our microRNA expression signature of renal cell carcinoma revealed that miR-218 expression was significantly decreased in cancer tissues, suggesting that miR-218 is a candidate tumor suppressor. We investigated the functional significance of miR-218 in cancer cells and identified what are to our knowledge novel miR-218 mediated cancer pathways in renal cell carcinoma.

MATERIALS AND METHODS

Gain of function studies using mature miR-218 were performed to investigate cell proliferation, migration and invasion in the A498 and 786-O renal cell carcinoma cell lines. To identify miR-218 mediated molecular pathways and responsible genes in renal cell carcinoma, we used gene expression and in silico database analyses. Loss of function assays were performed to investigate the functional significance of miR-218 target genes.

RESULTS

Restoration of mature miR-218 significantly inhibited RCC cell proliferation, migration and invasion. Gene expression studies and luciferase reporter assays showed that CAV2 involved in the focal adhesion pathway was directly regulated by miR-218. A silencing study of CAV2 revealed significant inhibition of cell proliferation, migration and invasion. CAV2 mRNA and protein expression was significantly up-regulated in renal cell carcinoma clinical specimens.

CONCLUSIONS

Loss of tumor suppressive miR-218 enhances cancer cell migration and invasion through dysregulation of the focal adhesion pathway, especially CAV2 as an oncogenic function in renal cell carcinoma. Tumor suppressive microRNA mediated cancer pathways and responsible genes provide new insights into the potential mechanisms of renal cell carcinoma oncogenesis and metastasis.

microRNA response elements-regulated TRAIL expression shows specific survival-suppressing activity on bladder cancer

Background

Bladder transitional cell carcinoma greatly threatens human health all over the world. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) shows a strong apoptosis-inducing effect on a variety of cancer cells including bladder cancer. However, adenovirus-mediated TRAIL expression still showed cytotoxicity to normal cells mainly due to lack of tumor specificity.

Methods

To solve the problem, we applied miRNA response elements (MREs) of miR-1, miR-133 and miR-218 to confer TRAIL expression with specificity to bladder cancer cells.

Results

Expression of miR-1, miR-133 and miR-218 was greatly decreased in bladder cancer than normal bladder tissue. Luciferase assay showed that application of the 3 MREs was able to restrain exogenous gene expression to within bladder cancer cells. Subsequently, we constructed a recombinant adenovirus with TRAIL expression regulated by MREs of miR-1, miR-133 and miR-218, namely Ad-TRAIL-MRE-1-133-218. qPCR, immunoblotting and ELISA assays demonstrated that Ad-TRAIL-MRE-1-133-218 expressed in bladder cancer cells, rather than normal bladder cells. The differential TRAIL expression also led to selective apoptosis-inducing and growth-inhibiting effect of Ad-TRAIL-MRE-1-133-218 on bladder cancers. Finally, bladder cancer xenograft in mouse models further confirmed that Ad-TRAIL-MRE-1-133-218 effectively suppressed the growth of bladder cancers.

Conclusions

Collectively, we demonstrated that MREs-based TRAIL delivery into bladder cancer cells was feasible and efficient for cancer gene therapy.

microRNA expression profile in a large series of bladder tumors: identification of a 3-miRNA signature associated with aggressiveness of muscle-invasive bladder cancer

The aim of this study was to evaluate the expression levels of microRNAs (miRNAs) in bladder tumors in order to identify miRNAs involved in bladder carcinogenesis with potential prognostic implications. Expression levels of miRNAs were assessed by quantitative real-time RT-PCR in 11 human normal bladder and 166 bladder tumor samples (86 non-muscle-invasive bladder cancer (NMIBC) and 80 muscle-invasive bladder cancer (MIBC)). The expression level of 804 miRNAs was initially measured in a well-defined series of seven NMIBC, MIBC and normal bladder samples (screening set). The most strongly deregulated miRNAs in tumor samples compared to normal bladder tissue were then selected for RT-PCR validation in a well-characterized independent series of 152 bladder tumors (validation set), and in six bladder cancer cell lines. Expression levels of these miRNAs were tested for their association with clinical outcome. A robust group of 15 miRNAs was found to be significantly deregulated in bladder cancer. Except for two miRNAs, miR-146b and miR-9, which were specifically upregulated in MIBC, the majority of miRNAs (n = 13) were deregulated in the same way in the two types of bladder tumors, irrespective of pathological stage : three miRNAs were upregulated (miR-200b, miR-182 and miR-138) and the other 10 miRNAs were downregulated (miR-1, miR-133a, miR-133b, miR-145, miR-143, miR-204, miR-921, miR-1281, miR-199a and miR-199b). A 3-miRNA signature (miR-9, miR-182 and miR-200b) was found to be related to MIBC tumor aggressiveness and was associated with both recurrence-free and overall survival in univariate analysis with a trend to significance in the multivariate analysis (p = 0.05). Our results suggested a promising individual prognostic value of these new markers.

Clinical significance of pituitary tumor transforming gene 1 and transgelin-2 in pancreatic cancer

Human pituitary tumor transforming gene 1 (PTTG1) is an oncogenic transcription factor that is overexpressed in many malignancies, especially cancers with metastatic potential, while transgelin-2 (TAGLN2) is an actin-binding protein shown to be a tumor suppressor. However, the expression and clinical significance of PTTG1 and TAGLN2 in pancreatic cancer remain unclear. The present study aimed to investigate the expression and clinical significance of PTTG1 and TAGLN2 in human primary pancreatic cancer. Seventy-five cases of human pancreatic cancer tissues were collected. The expression of PTTG1 and TAGLN2 protein was assessed using immunohistochemistry (IHC) through tissue microarray procedure. The clinicopathologic characteristics of all patients were analyzed. As a result, the expression of PTTG1 and TAGLN2 in cancerous tissues showed the positive staining mainly in the cytoplasm, and they were found in cancerous tissues with higher strong reactivity rate compared with the adjacent non-cancer tissues (ANCT) (56.0 percent vs 22.7 percent, P less than 0.001; 100 percent vs 84 percent, P=0.002), elevating with the ascending order of tumor malignancy. Furthermore, the positive expression of PTTG1 was associated with the gender of pancreatic cancer patients, but did not correlate with their age, pathological styles, tumor size, tumor sites, TNM staging, perineural infiltration and distant metastasis (each P greater than 0.05). In addition, Spearman rank correlation analysis showed the positive correlation of PTTG1 with TAGLN2 (r=0.624, P less than 0.001). Taken together, PTTG1 and TAGLN2 are highly expressed in human pancreatic cancer, and the positive expression of PTTG1 is associated with the gender of cancer patients, suggesting that it may represent a potential therapeutic target for the treatment of pancreatic cancer.

Tumor-suppressive microRNA-135a inhibits cancer cell proliferation by targeting the c-MYC oncogene in renal cell carcinoma

Recently, many studies have suggested that microRNAs (miRNAs) are involved in cancer cell development, invasion, and metastasis of various types of human cancers. In a previous study, miRNA expression signatures from renal cell carcinoma (RCC) revealed that expression of microRNA-135a (miR-135a) was significantly reduced in cancerous tissues. The aim of this study was to investigate the functional significance of miR-135a and to identify miR-135a-mediated molecular pathways in RCC cells. Restoration of mature miR-135a significantly inhibited cancer cell proliferation and induced G0 /G1 arrest in the RCC cell lines caki2 and A498, suggesting that miR-135a functioned as a potential tumor suppressor. We then examined miR-135a-mediated molecular pathways using genome-wide gene expression analysis and in silico analysis. A total of 570 downregulated genes were identified in miR-135a transfected RCC cell lines. To investigate the biological significance of potential miR-135a-mediated pathways, we classified putative miR-135a-regulated genes according to the Kyoto Encyclopedia of Genes and Genomics pathway database. From our in silico analysis, 25 pathways, including the cell cycle, pathways in cancer, DNA replication, and focal adhesion, were significantly regulated by miR-135a in RCC cells. Moreover, based on the results of this analysis, we investigated whether miR-135a targeted the c-MYC gene in RCC. Gain-of-function and luciferase reporter assays showed that c-MYC was directly regulated by miR-135a in RCC cells. Furthermore, c-MYC expression was significantly upregulated in RCC clinical specimens. Our data suggest that elucidation of tumor-suppressive miR-135a-mediated molecular pathways could reveal potential therapeutic targets in RCC.

Tumor suppressive microRNA-218 inhibits cancer cell migration and invasion through targeting laminin-332 in head and neck squamous cell carcinoma

Recent our microRNA (miRNA) expression signature revealed that expression of microRNA-218 (miR-218) was reduced in cancer tissues, suggesting a candidate of tumor suppressor in head and neck squamous cell carcinoma (HNSCC). The aim of this study was to investigate the functional significance of miR-218 and its mediated moleculer pathways in HNSCC. Restoration of miR-218 in cancer cells led to significant inhibition of cell migration and invasion activities in HNSCC cell lines (FaDu and SAS). Genome-wide gene expression analysis of miR-218 transfectants and in silico database analysis showed that focal adhesion pathway was a promising candidate of miR-218 target pathways. The laminins are an important and biologically active part of the basal lamina, the function of that are various such as influencing cell differentiation, migration and adhesion as well as proliferation and cell survival. Interestingly, all components of laminin-332 (LAMA3, LAMB3 and LAMC2) are listed on the candidate genes in focal adhesion pathway. Furthermore, we focused on LAMB3 which has a miR-218 target site and gene expression studies and luciferase reporter assays showed that LAMB3 was directly regulated by miR-218. Silencing study of LAMB3 demonstrated significant inhibition of cell migration and invasion. In clinical specimens with HNSCC, the expression levels of laminin-332 were significantly upregulated in cancer tissues compared to adjacent non-cancerous tissues. Our analysis data showed that tumor suppressive miR-218 contributes to cancer cell migration and invasion through regulating focal adhesion pathway, especially laminin-332. Tumor suppressive miRNA-mediated novel cancer pathways provide new insights into the potential mechanisms of HNSCC oncogenesis.

Differential expression profiles of microRNAs as potential biomarkers for the early diagnosis of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal malignancies worldwide. To reduce the high morbidity and mortality of the disease, sensitive and specific biomarkers for early detection are urgently needed. Tumor-specific microRNAs (miRNAs) seem to be potential biomarkers for the early diagnosis and treatment of cancer. In this study, differentially expressed miRNAs in tumor tissues and adjacent non-tumor tissues were detected by miRNA microarrays. Stem-loop real-time reverse transcription PCR was conducted to verify the candidate miRNAs discovered by microarray analysis. The data showed that hsa-miR-338-3p, hsa-miR‑218 and hsa-miR-139-5p were downregulated in tumor tissues compared with adjacent non-tumor tissues, while hsa-miR‑183, hsa-miR-574-5p, hsa-miR-21* and hsa-miR‑601 were upregulated in tumor tissues. Multiple regression analysis revealed the aberrant expression of hsa-miR-338-3p, hsa‑miR-139-5p, hsa-miR‑574-5p and hsa-miR-601 increased the risk of esophageal cancer. Furthermore, we found hsa-miR-21* was significantly increased in heavy drinking patients. Therefore, there is a set of differentially expressed miRNAs in esophageal cancer which may be associated with the incidence and development of ESCC. Differential expression profiles of miRNAs in ESCC may be promising biomarkers for the early screening of high-risk populations and early detection.