MicroRNAs in ovarian cancer biology and therapy resistance

Methylation-associated Has-miR-9 deregulation in paclitaxel- resistant epithelial ovarian carcinoma

Background

Drug resistance is still one of the key causes of death in epithelial ovarian carcinoma (EOC) patients, however there are very few strategies to reverse chemoresistance. Here we try to clarify whether and how miR-9 takes part in the regulation of paclitaxel sensitivity.

Methods

miR-9 expressions in EOC cells and tissues were detected by Realtime PCR. The target of miR-9 was validated through dual luciferase reporter assay and Western Blot. Methylation study, RNAi technique and cytotoxicity assay were used to determine the intrinsic mechanism of miR-9 in paclitaxel sensitivity regulation.

Results

miR-9 is down-regulated in paclitaxel resistant EOC. The patients with lower miR-9, Grade 3, Stage III –IV and suboptimal surgery present shorter survival time. miR-9 and suboptimal surgery are independent prognostic factors of EOC. Modulating miR-9 expression could change paclitaxel sensitivity of EOC cells. CCNG1, validated as a direct target of miR-9, mediates paclitaxel resistance. miR-9-1 and 3 gene hypermethylation would decrease miR-9 expression, while demethylation of miR-9 gene could restore miR-9 expression and improve paclitaxel sensitivity in chemoresistance EOC cells. Furthermore, methylation-associated miR-9 deregulation in EOC cells could be induced by paclitaxel exposure.

Conclusions

Methylation-associated miR-9 down-regulation is probably one of the key mechanisms for paclitaxel resistance in EOC cells, via targeting CCNG1. Our findings may also provide a new potential therapeutic target to reverse paclitaxel resistance in EOC patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1509-1) contains supplementary material, which is available to authorized users.

HGF/c-Met axis drives cancer aggressiveness in the neo-adjuvant setting of ovarian cancer

Ovarian cancer is the most lethal gynecologic malignancy. Recently, NACT (Neo Adjuvant Chemotherapy) has been tested as alternative approach for the management of ovarian cancer patients. A biological predictor helpful in selecting patients for NACT would be desirable. This study was aimed at identifying actionable mechanisms of resistance to NACT. Expression of a panel of microRNAs was screened in a discovery set of 85 patients. Analysis of the potential targets was conducted in the same RNAs by calculating significant correlations between microRNAs and genes. Quantitative fluorescent immunohistochemistry was employed in a validation set of 109 patients. MiR-193a-5p was significantly overexpressed in the NACT setting. Analysis of its potential targets demonstrated that this microRNA is also significantly correlated with HGF and MET genes. Analysis of protein expression in samples taken before and after NACT demonstrated that both HGF and c-Met are increased after NACT. Patients who relapse shortly after NACT exhibited the highest relative basal expression of both HGF and c-Met, while the opposite phenomenon was observed in the best responders. Mir-193a-5p, HGF and c-Met expression may help select eligible patients for this modality of treatment. Moreover, inhibitors of this pathway may improve the efficacy of NACT.

miRNA-196b inhibits cell proliferation and induces apoptosis in HepG2 cells by targeting IGF2BP1

Background

Tumor hypoxia is one of the features of tumor microenvironment that contributes to chemoresistance. miRNAs have recently been shown to play important roles in tumorigenesis and drug resistance. Moreover, hypoxia also regulates the expression of a series of miRNAs. However, the interaction between chemoresistance, hypoxia and miRNAs has not been explored yet. The aim of this study is to understand the mechanisms activated/inhibited by miRNAs under hypoxia that induce resistance to chemotherapy-induced apoptosis.

Methods

TaqMan low-density array was used to identify changes in miRNA expression when cells were exposed to etoposide under hypoxia or normoxia. The effects of miR-196b overexpression on apoptosis and cell proliferation were studied in HepG2 cells. miR-196b target mRNAs were identified by proteomic analysis, luciferase activity assay, RT-qPCR and western blot analysis.

Results

Results showed that hypoxia down-regulated miR-196b expression that was induced by etoposide. miR-196b overexpression increased the etoposide-induced apoptosis and reversed the protection of cell death observed under hypoxia. By a proteomic approach combined with bioinformatics analyses, we identified IGF2BP1 as a potential target of miR-196b. Indeed, miR-196b overexpression decreased IGF2BP1 RNA expression and protein level. The IGF2BP1 down-regulation by either miR-196b or IGF2BP1 siRNA led to an increase in apoptosis and a decrease in cell viability and proliferation in normal culture conditions. However, IGF2BP1 silencing did not modify the chemoresistance induced by hypoxia, probably because it is not the only target of miR-196b involved in the regulation of apoptosis.

Conclusions

In conclusion, for the first time, we identified IGF2BP1 as a direct and functional target of miR-196b and showed that miR-196b overexpression reverses the chemoresistance induced by hypoxia. These results emphasize that the chemoresistance induced by hypoxia is a complex mechanism.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0349-6) contains supplementary material, which is available to authorized users.

Epigenetic silencing of microRNA-199b-5p is associated with acquired chemoresistance via activation of JAG1-Notch1 signaling in ovarian cancer

Epithelial ovarian cancer is a highly lethal and aggressive gynecological malignancy. The high mortality rate is due in part to the fact that many advanced cancer patients become refractory to current chemotherapeutic agents, leading to tumor recurrence and death. However, the underlying mechanisms leading to chemoresistance remain obscure. Here, we report that the loss of miR-199b-5p due to progressive epigenetic silencing leads to the activation of the JAG1-mediated Notch1 signaling cascade, thereby leading to the development of acquired chemoresistance in ovarian cancer. Using miRCURY LNA™ microRNA array and Q-PCR analyses of two pairs of cisplatin-sensitive and –resistant ovarian cancer cell lines, we identified miR-199b-5p as significantly down-regulated in cisplatin-resistant ovarian cancer cells and confirmed that miR-199b-5p is clinically associated with advanced and poor survival ovarian cancers. Interestingly, the loss of miR-199b-5p could be restored by 5-Aza-dC-mediated demethylation, and methylated specific PCR (MS-PCR), bisulfite-sequencing and pyrosequencing revealed that the promoter region of miR-199b-5p was hypermethylated. Computational and mechanistic analyses identified JAG1 as a primary target of miR-199b-5p. Notably, the reduced expression of miR-199b-5p was found to be inversely correlated with the increased expression of JAG1 using an ovarian cancer tissue array. Enforced expression of miR-199b-5p sensitized ovarian cancer cells to cisplatin-induced cytotoxicity both in vitro and in vivo. Conversely, re-expression of miR-199b-5p and siRNA-mediated JAG1 knockdown or treatment with Notch specific inhibitor γ-secretase (GSI) attenuated JAG1-Notch1 signaling activity, thereby enhancing cisplatin-mediated cell cytotoxicity. Taken together, our study suggests that the epigenetic silencing of miR-199b-5p during tumor progression is significantly associated with acquired chemoresistance in ovarian cancer through the activation of JAG1-Notch1 signaling.

The passenger strand, miR-21-3p, plays a role in mediating cisplatin resistance in ovarian cancer cells

OBJECTIVE

Ovarian cancer is the deadliest gynaecological cancer. A major contributor to the poor survival rate is the development of chemoresistance to platinum-based therapies such as cisplatin and carboplatin. Here we aimed to test the role of miRNAs in the acquisition of drug resistance in ovarian cancer.

METHODS

We used microarrays to measure miRNA levels in the ovarian cancer cell line A2780 and its cisplatin-resistant derivative CP70. The role of miRNAs and the mRNA targets were tested using transfected miRNA mimics and siRNAs, respectively. Potential in vivo significance was investigated by analysing RNA levels in cohorts of ovarian cancer patients.

RESULTS

We identified several miRNAs that are increased in cisplatin-resistant cells. We show that most of these do not directly contribute to cisplatin resistance. Interestingly, miR-21-3p, the passenger strand of the known oncomiR, directed increased resistance to cisplatin in a range of ovarian cell lines. This effect was specific to the star strand, as miR-21-5p had the opposite effect and actually increased sensitivity of A2780 cells to cisplatin. We identify NAV3 as a potential target of miR-21-3p and show that knockdown of NAV3 increases resistance. Exosomes released by CP70 cells were also capable of increasing resistance in A2780 cells, although this was independent of miR-21-3p. Finally, we use publically available transcriptomic data to demonstrate that miR-21-3p is raised, while NAV3 is reduced, in ovarian tumours that are resistant to platinum treatment.

CONCLUSION

Our data suggest that miR-21-3p can induce cisplatin resistance in ovarian tumours, potentially by targeting the NAV3 gene.

Systems analysis reveals down-regulation of a network of pro-survival miRNAs drives the apoptotic response in dilated cardiomyopathy

Apoptosis is a hallmark of multiple etiologies of heart failure, including dilated cardiomyopathy. Since microRNAs are master regulators of cardiac development and key effectors of intracellular signaling, they represent novel candidates for understanding the mechanisms driving the increased dysfunction and loss of cardiomyocytes during cardiovascular disease progression. To determine the role of cardiac miRNAs in the apoptotic response, we used microarray technology to monitor miRNA levels in a validated murine phospholambam mutant model of dilated cardiomyopathy. 24 miRNAs were found to be differentially expressed, most of which have not been previously linked to dilated cardiomyopathy. We showed that individual silencing of 7 out of 8 significantly down-regulated miRNAs (mir-1, -29c, -30c, -30d, -149, -486, -499) led to a strong apoptotic phenotype in cell culture, suggesting they repress pro-apoptotic factors. To identify putative miRNA targets most likely relevant to cell death, we computationally integrated transcriptomic, proteomic and functional annotation data. We showed the dependency of prioritized target abundance on miRNA expression using RNA interference and quantitative mass spectrometry. We concluded that down regulation of key pro-survival miRNAs causes up-regulation of apoptotic signaling effectors that contribute to cardiac cell loss, potentially leading to system decompensation and heart failure.

Differential microRNA expression by Solexa sequencing in the sera of ovarian cancer patients

MicroRNAs are a class of small noncoding RNA which play important regulatory roles in a variety of cancers. MiRNA-specific expression profiles have been reported for several pathological conditions. In this study, we combined large scale parallel Solexa sequencing to identify 11 up-regulated miRNAs and 19 down-regulated miRNAs with computational techniques in the sera of ovarian cancer patients while using healthy serum as the control. Among the above, four miRNAs (miR-22, miR-93, miR-106b, miR-451) were validated by quantitative RT-PCR and found to be significantly aberrantly expressed in the serum of ovarian cancer patients (P<0.05). There were no significant differences between samples from cancer stage I/II and III/IV. However, the levels of miR-106b (p=0.003) and miR-451 (p=0.007) were significantly different in those patients under and over 51 yearsof age. MiR-451 and miR-93 were also specific when analyzed with reference to different levels of CA125. This study shows that Solexa sequencing provides a promising method for cancer-related miRNA profiling, and selectively expressed miRNAs could be used as potential serum-based biomarkers for ovarian cancer diagnosis.

miR-491-5p-induced apoptosis in ovarian carcinoma depends on the direct inhibition of both BCL-XL and EGFR leading to BIM activation

We sought to identify miRNAs that can efficiently induce apoptosis in ovarian cancer cells by overcoming BCL-X_L and MCL1 anti-apoptotic activity, using combined computational and experimental approaches. We found that miR-491-5p efficiently induces apoptosis in IGROV1-R10 cells by directly inhibiting BCL-X_L expression and by inducing BIM accumulation in its dephosphorylated form. This latter effect is due to direct targeting of epidermal growth factor receptor (EGFR) by miR-491-5p and consequent inhibition of downstream AKT and MAPK signalling pathways. Induction of apoptosis by miR-491-5p in this cell line is mimicked by a combination of EGFR inhibition together with a BH3-mimetic molecule. In contrast, SKOV3 cells treated with miR-491-5p maintain AKT and MAPK activity, do not induce BIM and do not undergo cell death despite BCL-X_L and EGFR downregulation. In this cell line, sensitivity to miR-491-5p is restored by inhibition of both AKT and MAPK signalling pathways. Altogether, this work highlights the potential of miRNA functional studies to decipher cell signalling pathways or major regulatory hubs involved in cell survival to finally propose the rationale design of new strategies on the basis of pharmacological combinations.

Effects of HMGA2 on malignant degree, invasion, metastasis, proliferation and cellular morphology of ovarian cancer cells

OBJECTIVE

To analyze effects of high mobility group AT-hook 2 (HMGA2) on malignant degree, invasion, metastasis, proliferation and cellular morphology of ovarian cancer cells.

METHODS

Three methods were applied to observe the effect on HMGA2 expression in ovarian cancer cells and ovarian epithelial cells.

RESULTS

After the application of siRNA-HMGA2, number of T29A2-cell clones was decreased, there was significant difference compared with the negative control Block-iT. After application of let-7c, number of T29A2+ cell clones was decreased significantly, however, after the application of Anti-let-7, the number of clones restored, and there was no significant difference compared with the negative control group. After interference, the number of T29A2- cells which passed through Matrigel polycarbonate membrane were significantly lower than the negative control group. After the treatment of siRNA-HMGA2, let-7c and sh-HMGA2 respectively, growth and proliferation of T29A2-, T29A2+ and SKOV3 were slower, and the phenomenon was most obvious in SKOV3. Stable interference of HMGA2 induced mesenchymal-epithelial changes in the morphology of SKOV3-sh-HMGA2.

CONCLUSIONS

HMGA2 can promote malignant transformation of ovarian cancer cells, enhance cell invasion and metastasis, and promote cell growth and proliferation of ovarian cancer cells, which can cause ovarian cancer to progress rapidly and affect the quality of life.

Uncovering molecular events associated with the chemosuppressive effects of flaxseed: a microarray analysis of the laying hen model of ovarian cancer

Background

The laying hen model of spontaneous epithelial ovarian cancer (EOC) is unique in that it is the only model that enables observations of early events in disease progression and is therefore also uniquely suited for chemoprevention trials. Previous studies on the effect of dietary flaxseed in laying hens have revealed the potential for both amelioration and prevention of ovarian cancer. The objective of this study was to assess the effect of flaxseed on genes and pathways that are dysregulated in tumors. We have used a bioinformatics approach to identify these genes, followed by qPCR validation, immunohistochemical localization, and in situ hybridization to visualize expression in normal ovaries and tumors from animals fed a control diet or a diet containing 10% flaxseed.

Results

Bioinformatic analysis of ovarian tumors in hens led to the identification of a group of highly up-regulated genes that are involved in the embryonic process of branching morphogenesis. Expression of these genes coincides with expression of E-cadherin in the tumor epithelium. Levels of expression of these genes in tumors from flax-fed animals are reduced 40-60%. E-cadherin and miR200 are both up-regulated in tumors from control-fed hens, whereas their expression is decreased 60-75% in tumors from flax-fed hens. This does not appear to be due to an increase in ZEB1 as mRNA levels are increased five-fold in tumors, with no significant difference between control-fed and flax-fed hens.

Conclusions

We suggest that nutritional intervention with flaxseed targets the pathways regulating branching morphogenesis and thereby alters the progression of ovarian cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-709) contains supplementary material, which is available to authorized users.

MiR-200a impairs glioma cell growth, migration, and invasion by targeting SIM2-s

Recently, single-minded homolog 2-short form (SIM2-s) was reported to be related to tumor development and progression and to be elevated in many human cancer cells. In this study, we investigated the factors that contribute to the regulation of SIM2-s expression in gliomas. The results showed that SIM2-s was elevated in gliomas. In addition, inhibition of SIM2-s reduced glioma cell growth, migration, and invasion. Next, we demonstrated that SIM2-s is a functional target of miR-200a. Further, miR-200a is downregulated in human glioma and inhibition of miR-200a caused upregulation of SIM2-s in T98G cells and promoted their motility. Finally, blockage of miR-200a expression in a mouse model of human glioma resulted in significant promotion of tumor growth. These findings suggest that miR-200a could serve as a therapeutic tool for glioma.

Advances in circulating microRNAs as diagnostic and prognostic markers for ovarian cancer

Ovarian cancer is one of the most lethal malignant gynecological tumors. More than 70% of patients with ovarian cancer are diagnosed at advanced stage. The 5-year survival in patients with advanced ovarian cancer is less than 30% because of the lack of effective biomarkers for diagnosis, prognosis, and personalized treatment. MicroRNA (miR) is a class of small noncoding RNAs that negatively regulate gene expression primarily through post-transcriptional repression. Many studies on tissue miR in ovarian cancer have been carried out and show great potential in clinical practice. However, tissue samples are not easily available because sampling causes injury. Researchers have started to focus on plasma/serum miR, assuming that blood samples may replace tissue samples in miR research in the future. Plasma/serum miR research is still in its early stages. Studies on its function in the early diagnosis of ovarian cancer have achieved some progress, but plasma/serum miR profiling for prognosis and personalized treatment of ovarian cancer remains unknown. A thorough understanding of the function of plasma/serum miR in ovarian cancer will facilitate early diagnosis and improve treatment for ovarian cancer.

MicroRNAs as prognostic markers in ovarian cancer

Ovarian cancer (OC) is the most lethal gynecological malignancy among women. Over 70% of women with OC are diagnosed in advanced stages and most of these cases are incurable. Although most patients respond well to primary chemotherapy, tumors become resistant to treatment. Mechanisms of chemoresistance in cancer cells may be associated with mutational events and/or alterations of gene expression through epigenetic events. Although focusing on known genes has already yielded new information, previously unknown non-coding RNAs, such as microRNAs (miRNAs), also lead insight into the biology of chemoresistance. In this review we summarize the current evidence examining the role of miRNAs as biomarkers of response and survival to therapy in OC. Beside their clinical implications, we also discuss important differences between studies that may have limited their use as clinical biomarkers and suggest new approaches.

Application of microRNA in diagnosis and treatment of ovarian cancer

Ovarian cancer has a poor prognosis because early detection is difficult and recurrent ovarian cancer is usually drug-resistant. The morbidity and mortality of ovarian cancer are high worldwide and new methods of diagnosis and therapy are needed. MicroRNAs (miRNAs) are posttranscriptional regulators of gene expression that are involved in carcinogenesis, metastasis, and invasion. Thus, miRNAs are likely to be useful as diagnostic and prognostic biomarkers and for cancer therapy. Many miRNAs have altered expression in ovarian cancer compared to normal ovarian tissues and these changes may be useful for diagnosis and treatment. For example, deficiencies of enzymes including Dicer and Drosha that are required for miRNA biogenesis may be adverse prognostic factors; miRNAs such as miR-214 and miR-31, which are involved in drug resistance, and the miR-200 family, which is implicated in metastasis, may serve as biomarkers; and transfection of downregulated miRNAs and inhibition of upregulated miRNAs may be effective for treatment of ovarian cancer. Chemotherapy targeting epigenetic mechanisms associated with miRNAs may also be effective to reverse gene silencing.

Micro-RNAs and ovarian cancer: the state of art and perspectives of clinical research

Dysregulation of microRNA (mi-RNA) expression plays a major role in the development and progression of most human malignancies. Members of the miR-200 family, miR-182, miR-214 and miR-221 are frequently up-regulated, whereas miR-100, let-7i, miR-199a, miR-125b, mir-145 and miR-335 are often down-regulated in ovarian cancer compared with normal ovarian tissue. Most mi-RNA signatures are overlapping in different tumor histotypes but some mi-RNAs seem to be histotype specific. For instance, the endometrioid type shares with the serous and clear cell types the up-regulation of miR-200 family members, but also presents over-expression of miR-21, miR-202 and miR-205. Clear cell carcinoma has a significantly higher expression of miR-30a and miR-30a*, whereas mucinous histotype has elevated levels of miR-192/194. In vitro and in vivo investigations have shown that several mi-RNAs can modulate the sensitivity of ovarian cancer to platinum and taxane, and clinical studies have suggested that mi-RNA profiling may predict the outcome of patients with this malignancy. Some mi-RNAs could be used as biomarkers to identify patients that might benefit from the addition of molecularly targeted agents (i.e. anti-angiogenic agents, MET inhibitors and poly(ADP-ribose) polymerase (PARP) inhibitors) to standard chemotherapy. Moreover, mi-RNAs could represent potential targets for the development of novel therapies.

Use of microRNAs in personalized medicine

Personalized medicine comprises the genetic information together with the phenotypic and environmental factors to yield healthcare tailored to an individual and removes the limitations of the "one-size-fits-all" therapy approach. This provides the opportunity to translate therapies from bench to clinic, to diagnose and predict disease, and to improve patient-tailored treatments based on the unique signatures of a patient's disease and further to identify novel treatment schedules. Nowadays, tiny noncoding RNAs, called microRNAs, have captured the spotlight in molecular biology with highlights like their involvement in DNA translational control, their impression on mRNA and protein expression levels, and their ability to reprogram molecular signaling pathways in cancer. Realizing their pivotal roles in drug resistance, they emerged as diagnostic targets orchestrating drug response in individualized therapy examples. It is not premature to think that researchers could have the US Food and Drug Administration (FDA)-approved kit-based assays for miRNA analysis in the near future. We think that miRNAs are ready for prime time.

Synergetic regulatory networks mediated by oncogene-driven microRNAs and transcription factors in serous ovarian cancer

Although high-grade serous ovarian cancer (OVC) is the most lethal gynecologic malignancy in women, little is known about the regulatory mechanisms in the cellular processes that lead to this cancer. Recently, accumulated lines of evidence have shown that the interplay between transcription factors (TFs) and microRNAs (miRNAs) is critical in cellular regulation during tumorigenesis. A comprehensive investigation of TFs and miRNAs, and their target genes, may provide a deeper understanding of the regulatory mechanisms in the pathology of OVC. In this study, we have integrated three complementary algorithms into a framework, aiming to infer the regulation by miRNAs and TFs in conjunction with gene expression profiles. We demonstrated the utility of our framework by inferring 67 OVC-specific regulatory feed-forward loops (FFL) initiated by miRNAs or TFs in high-grade serous OVC. By analyzing these regulatory behaviors, we found that all the 67 FFLs are consistent in their regulatory effects on genes that are jointly targeted by miRNAs and TFs. Remarkably, we unveiled an unbalanced distribution of FFLs with different oncogenic effects. In total, 31 of the 67 coherent FFLs were mainly initiated by oncogenes. On the contrary, only 4 of the FFLs were initiated by tumor suppressor genes. These overwhelmingly observed oncogenic genes were further detected in a sub-network with 32 FFLs centered by miRNA let-7b and TF TCF7L1 to regulate cell differentiation. Closer inspection of 32 FFLs revealed that 75% of the miRNAs reportedly play functional roles in cell differentiation, especially when enriched in epithelial-mesenchymal transitions. This study provides a comprehensive pathophysiological overview of recurring coherent circuits in OVC that are co-regulated by miRNAs and TFs. The prevalence of oncogenic coherent FFLs in serous OVC suggests that oncogene-driven regulatory motifs could cooperatively act upon critical cellular processes such as cell differentiation in a highly efficient and consistent manner.

Cancer development, progression, and therapy: an epigenetic overview

Carcinogenesis involves uncontrolled cell growth, which follows the activation of oncogenes and/or the deactivation of tumor suppression genes. Metastasis requires down-regulation of cell adhesion receptors necessary for tissue-specific, cell-cell attachment, as well as up-regulation of receptors that enhance cell motility. Epigenetic changes, including histone modifications, DNA methylation, and DNA hydroxymethylation, can modify these characteristics. Targets for these epigenetic changes include signaling pathways that regulate apoptosis and autophagy, as well as microRNA. We propose that predisposed normal cells convert to cancer progenitor cells that, after growing, undergo an epithelial-mesenchymal transition. This process, which is partially under epigenetic control, can create a metastatic form of both progenitor and full-fledged cancer cells, after which metastasis to a distant location may occur. Identification of epigenetic regulatory mechanisms has provided potential therapeutic avenues. In particular, epigenetic drugs appear to potentiate the action of traditional therapeutics, often by demethylating and re-expressing tumor suppressor genes to inhibit tumorigenesis. Epigenetic drugs may inhibit both the formation and growth of cancer progenitor cells, thus reducing the recurrence of cancer. Adopting epigenetic alteration as a new hallmark of cancer is a logical and necessary step that will further encourage the development of novel epigenetic biomarkers and therapeutics.

The complete exosome workflow solution: from isolation to characterization of RNA cargo

Exosomes are small (30–150 nm) vesicles containing unique RNA and protein cargo, secreted by all cell types in culture. They are also found in abundance in body fluids including blood, saliva, and urine. At the moment, the mechanism of exosome formation, the makeup of the cargo, biological pathways, and resulting functions are incompletely understood. One of their most intriguing roles is intercellular communication—exosomes function as the messengers, delivering various effector or signaling macromolecules between specific cells. There is an exponentially growing need to dissect structure and the function of exosomes and utilize them for development of minimally invasive diagnostics and therapeutics. Critical to further our understanding of exosomes is the development of reagents, tools, and protocols for their isolation, characterization, and analysis of their RNA and protein contents. Here we describe a complete exosome workflow solution, starting from fast and efficient extraction of exosomes from cell culture media and serum to isolation of RNA followed by characterization of exosomal RNA content using qRT-PCR and next-generation sequencing techniques. Effectiveness of this workflow is exemplified by analysis of the RNA content of exosomes derived from HeLa cell culture media and human serum, using Ion Torrent PGM as a sequencing platform.

MiR-27a modulates the MDR1/P-glycoprotein expression by inhibiting FZD7/β-catenin pathway in hepatocellular carcinoma cells

Chemotherapy has been widely used to treat cancer, however, the appearance of multiple drug resistance (MDR) in cancer patients is regarded as a major clinical obstacle to successful chemotherapy. MicroRNAs (miRNAs) are evolutionary conserved small RNAs that regulate gene expression at the post-transcriptional level and have been shown to regulate cell differentiation, development, proliferation and apoptosis. Nevertheless, the involvement of miRNAs and their roles in the development of MDR in liver cancer are not fully understood. Our study found that the expression of miR-27a was down-regulated in the multidrug-resistant hepatocellular carcinoma cell line BEL-7402/5-fluorouracil (BEL/5-FU) compared with its parental BEL-7402 cell line, while the MDR1/P-glycoprotein expression was elevated. Overexpression of miR-27a by transfecting with miR-27a mimics in the BEL/5-FU cells could reduce the MDR1/P-glycoprotein and β-catenin expressions, enhance the sensitivity of these cells to 5-fluorouracil and 5-fluorouracil-induced apoptosis. Moreover, up-regulation of miR-27a did not decrease the FZD7 mRNA level, but significantly reduce its protein expression in BEL/5-FU cells. It was also confirmed that reduction of FZD7 by RNA interference induced inhibitory effects on the expression of MDR1/P-glycoprotein and β-catenin, similar to miR-27a. Taken together, our findings suggest that miR-27a could function as a novel regulator to reverse MDR in hepatocellular carcinoma cells by inhibiting the FZD7/β-catenin pathway.

MicroRNA and transcription factor mediated regulatory network for ovarian cancer: regulatory network of ovarian cancer

A better understanding on the regulatory interactions of microRNA (miRNA) target genes and transcription factor (TF) target genes in ovarian cancer may be conducive for developing early diagnosis strategy. Thus, gene expression data and miRNA expression data were downloaded from The Cancer Genome Atlas in this study. Differentially expressed genes and miRNAs were selected out with t test, and Gene Ontology enrichment analysis was performed with DAVID tools. Regulatory interactions were retrieved from miRTarBase, TRED, and TRANSFAC, and then networks for miRNA target genes and TF target genes were constructed to globally present the mechanisms. As a result, a total of 1,939 differentially expressed genes were identified, and they were enriched in 28 functions, among which cell cycle was affected to the most degree. Besides, 213 differentially expressed miRNAs were identified. Two regulatory networks for miRNA target genes and TF target genes were established and then both were combined, in which E2F transcription factor 1, cyclin-dependent kinase inhibitor 1A, cyclin E1, and miR-16 were the hub genes. These genes may be potential biomarkers for ovarian cancer.

Cellular, histologic, and molecular changes associated with endometriosis and ovarian cancer

Our understanding of the pathogenesis of endometriosis is rapidly evolving as early molecular events are increasingly identified. Endometriosis is associated with increased risk of ovarian cancer and exhibits neoplastic phenotypes including invasion of stromal tissue and lymphatic spread to distant organs. This review of the literature establishes the clinical, epidemiologic, and pathologic correlation between endometriosis and low-grade ovarian cancer. Genetic studies have demonstrated that endometriotic lesions have mutations in genes directly related to neoplasms, in particular the p53, KRAS, PTEN, and ARID1A genes, which suggests a direct transition from a subset of endometriotic lesions to invasive carcinomas. The identification of both genetic and epigenetic biomarkers including microRNAs are essential for identifying patients at risk for the transition to neoplasia.

microRNA-214-mediated UBC9 expression in glioma

It has been reported that ubiquitin-conjugating enzyme 9 (Ubc9), the unique enzyme2 in the sumoylation pathway, is up-regulated in many cancers. However, the expression and regulation of UBC9 in glioma remains unknown. In this study, we found that Ubc9 was up-regulated in glioma tissues and cell lines compared to a normal control. UBC9 knockdown by small interfering RNA (siRNA) affected cell proliferation and apoptosis in T98G cells. Further experiments revealed that microRNA (miR)-214 directly targeted the 3' untranslated region (UTR) of UBC9 and that there was an inverse relationship between the expression levels of miR-214 and UBC9 protein in glioma tissues and cells. miR-214 overexpression suppressed the endogenous UBC9 protein and affected T98G cell proliferation. These findings suggest that miR-214 reduction facilitates UBC9 expression and is involved in the regulation of glioma cell proliferation. [BMB Reports 2012; 45(11): 641-646]

Emerging role of cancer stem cells in the biology and treatment of ovarian cancer: basic knowledge and therapeutic possibilities for an innovative approach

In 2013 there will be an estimated 22,240 new diagnoses and 14,030 deaths from ovarian cancer in the United States. Despite the improved surgical approach and the novel active drugs that are available today in clinical practice, about 80% of women presenting with late-stage disease have a 5-year survival rate of only 30%. In the last years a growing scientific knowledge about the molecular pathways involved in ovarian carcinogenesis has led to the discovery and evaluation of several novel molecular targeted agents, with the aim to test alternative models of treatment in order to overcome the clinical problem of resistance. Cancer stem cells tend to be more resistant to chemotherapeutic agents and radiation than more differentiated cellular subtypes from the same tissue. In this context the study of ovarian cancer stem cells is taking on an increasingly important strategic role, mostly for the potential therapeutic application in the next future. In our review, we focused our attention on the molecular characteristics of epithelial ovarian cancer stem cells, in particular on possible targets to hit with targeted therapies.

MiRNA expression signature for potentially predicting the prognosis of ovarian serous carcinoma

One of the best prognostic predictors for patients with epithelial ovarian cancer is the Federation of Obstetrics and Gynecology (FIGO) stage at diagnosis. Advanced-stage ovarian serous carcinoma (OSC) generally have poor prognosis. The goal of this study is to develop and validate a miRNA expression profile that can differentiate the OSC at early and advanced stages and study its correlation with the prognosis of OSC. To identify a unique microRNA (miRNA) pattern associated with the progression of OSC at early and advanced stages, a miRNA microarray was performed using Chinese tumor bank specimens of patients with OSC stage I or III in a retrospective analysis. The expression of four dysregulated miRNAs was validated using quantitative real-time polymerase chain reaction (qRT-PCR) in an external cohort of 51 cases of OSC samples at stages I and III. Kaplan-Meier analysis was performed to analyze the correlation between the expression of some miRNAs and prognosis. Of the 768 miRNAs analyzed in the microarray, 26 miRNAs were significantly either up- or downregulated, with at least a 2-fold difference, in OSC stage I compared with stage III. The qRT-PCR results showed that miR-510, miR-509-5p, and miR-508-3p were significantly downregulated and that miR-483-5p was upregulated in stage III OSC compared with stage I, which was consistent with the microarray results. Kaplan-Meier analysis showed low miR-510 expression, low miR-509-5p expression, and advanced FIGO stage, and chemotherapy resistance were significantly associated with poorer overall survival (P < 0.05). Our results suggest that miRNAs may play a role in the progression of OSC, and miR-510 and miR-509-5p may be considered novel-candidate clinical biomarkers for predicting OSC outcome.

miRNA expression pattern associated with prognosis in elderly patients with advanced OPSC and OCC

The long-term survival for elderly patients with advanced ovarian papillary serous carcinoma (OPSC) does not exceed 30%, and the incidence and prognosis rise continuously after menopause. The aim of this study was to identify the differences in key miRNAs and their potential regulators through miRNA microarray analysis, functional target prediction, and clinical outcome between the elderly patients with advanced OPSC and ovarian clear cell carcinoma (OCC) who all suffered poor prognosis, to identify the pathogenetic basis, and to improve the understanding of the molecular basis of advanced OPCS in elderly patients. Through microarray analysis, we found 52 unique miRNAs with significant fold‑change in expression levels, of which 9 were upregulated, whereas 43 were downregulated in OCC patients compared to elderly OPSC patients with advanced stage. Among these prediction miRNAs, miR-30a, miR-30e and miR-505 were found to have some common cancer-related targets. Lower expression of these three miRNAs of advanced OPSC in elderly patients, all associated with significantly poorer survival rate, strongly suggesting that they could be critical oncogenes and take important roles in OPSC etiology in elderly patients with advantaged stage. Functional analyses support the above hypothesis. Their targets, ATF3, STMN1 and MYC suggest that OPSC also has aggressive biological behavior when presented with advanced stage, and support the epidemiology results that incidence and mortality of advanced OPSC increases continuously. miR-30a, miR-30e and miR-505 may be important pathogenetic factors for OPSC in elderly patients with advanced stage. Age could be regarded as a continuous covariate in this process. This may improve the understanding of molecular underpinnings of advanced OPSC in elderly patients, and provide improved diagnostic, prognostic and therapeutic approaches.

Chemoresistance in ovarian cancer linked to expression of microRNAs

We evaluated the differential expression of several microRNAs (miRNAs) among malignant cells in ascites and matched omental metastasis in patients with epithelial ovarian cancer (EOC). Ascites and omental tumors were collected prospectively from five patients who were undergoing primary surgical cytoreduction. Patient samples were processed and treated with carboplatin, paclitaxel and combination chemotherapy. Cell viability was evaluated and miRNA profiling was performed on both tumor cells from ascites fluid and omental cake. Quantitative real-time PCR (RT-q-PCR) and western blots were used to evaluate expressions of miRNA-21 and miRNA -214 and associated proteins. Malignant cells in ascites showed greater cell viability when treated with carboplatin compared to omental metastasis. A significant up-regulation of miRNA-21 and miRNA-214 was observed in malignant cells of ascites compared to omental metastasis; this was confirmed by both cell viability assay and RT-q-PCR. Ours is the first report that demonstrates significant up-regulation of miRNA-21 and miRNA-214 in tumor cells from ascites of patients with EOC compared to omental metastasis. This finding has important implications for intrinsic carboplatin resistance in these patients.

MicroRNA profile of paclitaxel-resistant serous ovarian carcinoma based on formalin-fixed paraffin-embedded samples

Background

To assess the feasibility of validating microRNA (miRNA) profile related to paclitaxel-sensitivity in formalin-fixed paraffin-embedded (FFPE) samples of serous ovarian carcinoma (OC) patients.

Methods

Deregulated miRNAs identified by miRNA microarray were further detected in 45 FFPE OC samples using Realtime PCR. Correlations between paired FFPE and frozen tumor samples were analyzed. Survival times were compared between 6 high and low miRNAs groups. Western blot and luciferase reporter assay were used for validating the target of miRNA.

Results

Sixteen up-regulated miRNAs and twenty-three down-regulated miRNAs were revealed in pacilitaxel-resistant ST30 cells. The up-regulated miRNAs (miR-320a, 22 and 129-5p) and down-regulated miRNAs (miR-9, 155 and 640) were confirmed in paclitaxel-resistant FFPE tumor samples, compared with paclitaxel-sensitive samples. Higher miR-9 and miR-640 showed better survival time in OC patients. Expressions of miR-9, 155 and 22 in FFPE samples were closely mimicked by those in frozen tissues. RAB34 was validated as a direct target of miR-9.

Conclusions

We validated miRNA profile in pacilitaxel-resistant OC using FFPE samples, which might enable treatment stratification and help us to predict outcomes in OC patients. FFPE samples are feasible materials for miRNA research.

Cancerous ovarian stem cells: obscure targets for therapy but relevant to chemoresistance

Chemotherapy with platinum and taxanes is the first line of treatment for all epithelial ovarian cancer (EOC) patients after debulking surgery. Even though the treatment is initially effective in 80% of patients, recurrent cancer is inevitable in the vast majority of cases. Emerging evidence suggests that some tumor cells can survive chemotherapy by activating the self-renewal pathways resulting in tumor progression and clinical recurrence. These defined population of cells commonly termed as "cancer stem cells" (CSC) may generate the bulk of the tumor by using differentiating pathways. These cells have been shown to be resistant to chemotherapy and, to have enhanced tumor initiating abilities, suggesting CSCs as potential targets for treatment. Recent studies have introduced a new paradigm in ovarian carcinogenesis which proposes in situ carcinoma at the fimbrial end of the fallopian tube to generate high-grade serous ovarian carcinomas, in contrast to ovarian cortical inclusion cysts (CIC) which produce borderline and low grade serous, mucinous, endometrioid, and clear cell carcinomas. This review summarizes recent advances in our understanding of the cellular origin of EOC and the molecular mechanisms defining the basis of CSC in EOC progression and chemoresistance. Using a model ovarian cancer cell line, we highlight the role of CSC in response to chemotherapy, and relate how CSCs may impact on chemoresistance and ultimately recurrence. We also propose the molecular targeting of CSCs and suggest ways that may improve the efficacy of current chemotherapeutic regimens needed for the management of this disease.

Identification of genes and microRNAs involved in ovarian carcinogenesis

MicroRNAs (miRNAs) play roles in the clinic, both as diagnostic and therapeutic tools. The identification of relevant microRNAs is critically required for ovarian cancer because of the prevalence of late diagnosis and poor treatment options currently. To identify miRNAs involved in the development or progression of ovarian cancer, we analyzed gene expression profiles downloaded from Gene Expression Omnibus. Comparison of expression patterns between carcinomas and the corresponding normal ovarian tissues enabled us to identify 508 genes that were commonly up-regulated and 1331 genes that were down-regulated in the cancer specimens. Function annotation of these genes showed that most of the up-regulated genes were related to cell cycling, and most of the down-regulated genes were associated with the immune response. When these differentially expressed genes were mapped to MiRTarBase, we obtained a total of 18 key miRNAs which may play important regulatory roles in ovarian cancer. Investigation of these genes and microRNAs should help to disclose the molecular mechanisms of ovarian carcinogenesis and facilitate development of new approaches to therapeutic intervention.

Ovarian cancer emerging subtypes: role of oxidative stress and fibrosis in tumour development and response to treatment

Epithelial ovarian cancer is a silent disease of usually late diagnosis and poor prognosis. Currently treatment options are limited and mainly consist of surgery followed by taxol- and platinum-based chemotherapy. Patient response to treatment is difficult to predict and there is a serious need for anticipating tumour response and orientating medical choices. In that aim, recent researches have focused on molecular aspects of ovarian tumours that could help patient stratification. We review here published discoveries in that field. We emphasize that signatures, defined by combining miRNA and transcriptomic data, enlighten important aspects of ovarian cancer biology and reliably stratify patients. The miR-200-dependent "Oxidative stress" and "Fibrosis" signatures are promising in patient stratification for defining oriented therapeutic strategies. Indeed, the "Stress" patients survive longer than the "Fibrosis" patients, who exhibit partial debulking and incomplete response to chemotherapy. Interestingly, these two subgroups might benefit from specifically targeted therapeutic approaches, as discussed here.

Multilevel omic data integration in cancer cell lines: advanced annotation and emergent properties

Background

High-throughput (omic) data have become more widespread in both quantity and frequency of use, thanks to technological advances, lower costs and higher precision. Consequently, computational scientists are confronted by two parallel challenges: on one side, the design of efficient methods to interpret each of these data in their own right (gene expression signatures, protein markers, etc.) and, on the other side, realization of a novel, pressing request from the biological field to design methodologies that allow for these data to be interpreted as a whole, i.e. not only as the union of relevant molecules in each of these layers, but as a complex molecular signature containing proteins, mRNAs and miRNAs, all of which must be directly associated in the results of analyses that are able to capture inter-layers connections and complexity.

Results

We address the latter of these two challenges by testing an integrated approach on a known cancer benchmark: the NCI-60 cell panel. Here, high-throughput screens for mRNA, miRNA and proteins are jointly analyzed using factor analysis, combined with linear discriminant analysis, to identify the molecular characteristics of cancer. Comparisons with separate (non-joint) analyses show that the proposed integrated approach can uncover deeper and more precise biological information. In particular, the integrated approach gives a more complete picture of the set of miRNAs identified and the Wnt pathway, which represents an important surrogate marker of melanoma progression. We further test the approach on a more challenging patient-dataset, for which we are able to identify clinically relevant markers.

Conclusions

The integration of multiple layers of omics can bring more information than analysis of single layers alone. Using and expanding the proposed integrated framework to integrate omic data from other molecular levels will allow researchers to uncover further systemic information. The application of this approach to a clinically challenging dataset shows its promising potential.

Bioinformatic analysis of chemokine (C-C motif) ligand 21 and SPARC-like protein 1 revealing their associations with drug resistance in ovarian cancer

Chemokine (C-C motif) ligand 21 (CCL21) and SPARC-like protein 1 (SPARCL1/MAST9/hevin/SC-1) are associated with various biological behavior in the development of cancers. Although the expression of CCL21 and SPARCL1 is downregulated in many solid tumors, their roles in ovarian cancer and their associations with drug resistance have rarely been studied. We performed a comprehensive bioinformatic analysis consisting of motif analysis, literature co-occurrence, gene/protein-gene/protein interaction network, protein-small molecule interaction network, and microRNAs enrichments which revealed that CCL21 and SPARCL1 directly or indirectly interact with a number of genes, proteins, small molecules and pathways associated with drug resistance in ovarian and other cancers. These results suggested that CCL21 and SPARCL1 may contribute to drug resistance in ovarian cancer. This study provided important information for further investigation of drug resistance-related functions of CCL21 and SPARCL1 in ovarian cancer.

MiR-200c and HuR in ovarian cancer

BACKGROUND

MicroRNAs in solid malignancies can behave as predictors of either good or poor outcome. This is the case with members of the miR-200 family, which are the primary regulators of the epithelial to mesenchymal transition and have been reported to act as both oncogenes and tumor suppressors. This study assessed the role of miR-200c as regulator of class III β-tubulin (TUBB3), a factor associated with drug-resistance and poor prognosis in ovarian cancer.

METHODS

Expression of miR-200c was assessed in a panel of ovarian cancer cell lines with inherent or acquired drug-resistance. Stable overexpression of miR-200c was obtained in A2780 and Hey cell lines. Crosslinking-coupled affinity purification method and ribonucleic-immunoprecipitation assay were used to characterise the complexes between miR-200c, HuR and 3'UTR region of TUBB3 mRNA. Nanofluidic technology and immunohistochemistry were used to analyze the expression of HuR, TUBB3 and miR-200c in 220 ovarian cancer patients.

RESULTS

In a panel of ovarian adenocarcinoma cell lines, we observed a direct correlation between miR-200c expression and chemoresistance. In A2780 cells miR-200c targeted TUBB3 3'UTR, while a positive correlation was observed between miR-200c and TUBB3 expression in most of the other cell lines. Through the analysis of 3'UTR-associated complexes, we found that the miR-200c can increase the association of the RNA binding protein HuR with TUBB3 mRNA, whereas HuR binding enhanced TUBB3 mRNA translation. Most importantly, in our analysis on 220 ovarian cancer patients we observed that overexpression of miR-200c correlated with poor or good outcome depending on the cellular localization of HuR.

CONCLUSION

This study suggests a model for the combined regulatory activity of miR-200c and HuR on TUBB3 expression in ovarian cancer. When HuR is nuclear, high expression of miR-200c inhibits TUBB3 expression and results in a good prognosis, whereas when HuR occurs in cytoplasm, the same miRNA enhances TUBB3 expression and produces a poor outcome. These findings reveal the usefulness of multidimensional analysis in the investigation of the prognostic role of miRNA expression.

miR-137 restoration sensitizes multidrug-resistant MCF-7/ADM cells to anticancer agents by targeting YB-1

Multidrug resistance (MDR) to chemotherapeutic agents is a major obstacle to successful treatment in breast cancer patients. The aims of this study were to investigate whether miR-137 was involved in the regulation of MDR, and to explore the mechanism of miR-137 on the sensitivity of MCF-7/ADM cells. miR-137 was downregulated in MCF-7/ADM cells, and its expression was found to inversely correlate with Y-box binding protein-1 (YB-1) and P-glycoprotein (P-gp) levels in breast cancer cells. Furthermore, YB-1 was confirmed as a target of miR-137 by luciferase reporter assay and western blot analysis. Moreover, elevated expression of miR-137 reduced the protein expression levels of YB-1 and P-gp, mimicking the effect of YB-1 knockdown in the sensitivity of MCF-7/ADM cells to anticancer agents, whereas restoration of YB-1 diminished this effect. In conclusion, our results demonstrated that miR-137 was involved in MDR in cancer through modulation of P-gp by targeting YB-1, suggesting that miR-137 might be a potential target for preventing and reversing MDR in tumor cells.

Ovarian cancer stem cells: a new target for cancer therapy

Ovarian cancer is a highly lethal disease among all gynecologic malignancies and is the fifth leading cause of cancer-related death in women. Although the standard combination of surgery and chemotherapy was initially effective in patients with ovarian cancer, disease relapse commonly occurred due to the generation of chemoresistance. It has been reported that cancer stem cells (CSCs) are involved in drug resistance and cancer recurrence. Over the past decades, increasing studies have been done to identify CSCs from human ovarian cancer cells. The present paper will summarize different investigations on ovarian CSCs, including isolation, mechanisms of chemoresistance, and therapeutic approaches. Although there are still numerous challenges to translate basic research to clinical applications, understanding the molecular details of CSCs is essential for developing effective strategies to prevent ovarian cancer and its recurrence.

Establishment of primary cultures from ovarian tumor tissue and ascites fluid

We have refined the technique for isolating and propagating cultures of primary epithelial ovarian cancer (EOC) cells derived from solid tumors and ascites. Both protocols involve a simple yet rapid method for the growth and propagation of EOC tumor and ascites cells in a basal culture medium without the addition of growth factors. Isolation of tumor EOC cells involves the mechanical disruption of the tumor tissue with the help of a cell scraper, while ascites-derived EOC cells are mixed with growth medium and placed directly into culture with very little manipulation. We further describe a partial trypsinization method to eliminate fibroblast contamination from primary EOC cells derived from solid tumors. These methods allow for the direct application of many molecular, cellular, and functional analyses within a few weeks of initial isolation, with the added potential of retrospective analyses of archived cells and tissues. Thus, we have included steps for long-term cryopreservation of early-passage EOC cells. Initial isolation of EOC cells can be completed within 1 h, and primary cells are further expanded in culture for several weeks.

Early detection biomarkers for ovarian cancer

Despite the widespread use of conventional and contemporary methods to detect ovarian cancer development, ovarian cancer remains a common and commonly fatal gynecological malignancy. The identification and validation of early detection biomarkers highly specific to ovarian cancer, which would permit development of minimally invasive screening methods for detecting early onset of the disease, are urgently needed. Current practices for early detection of ovarian cancer include transvaginal ultrasonography, biomarker analysis, or a combination of both. In this paper we review recent research on novel and robust biomarkers for early detection of ovarian cancer and provide specific details on their contributions to tumorigenesis. Promising biomarkers for early detection of ovarian cancer include KLK6/7, GSTT1, PRSS8, FOLR1, ALDH1, and miRNAs.

MicroRNAs in opioid pharmacology

MicroRNAs (miRNA), a class of ~22-nucleotide RNA molecules, are important gene regulators that bind to the target sites of mRNAs to inhibit the gene expressions either through translational inhibition or mRNA destabilization. There are growing evidences that miRNAs have played several regulatory roles in opioid pharmacology. Like other research fields such as cancer biology, the area where numerous miRNAs are found to be involved in gene regulation, we assume that in opioid studies including research fields of drug additions and opioid receptor regulation, there may be more miRNAs waiting to be discovered. This review will summarize our current knowledge of miRNA functions on opioids biology and briefly describe future research directions of miRNAs related to opioids.

Attributes of Oct4 in stem cell biology: perspectives on cancer stem cells of the ovary

Epithelial ovarian cancer (EOC) remains the most lethal of all the gynaecological malignancies with drug resistance and recurrence remaining the major therapeutic barrier in the management of the disease. Although several studies have been undertaken to understand the mechanisms responsible for chemoresistance and subsequent recurrence in EOC, the exact mechanisms associated with chemoresistance/recurrence continue to remain elusive. Recent studies have shown that the parallel characteristics commonly seen between embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSC) are also shared by a relatively rare population of cells within tumors that display stem cell-like features. These cells, termed 'cancer initiating cells' or 'cancer stem cells (CSCs)' have been shown not only to display increased self renewal and pluripotent abilities as seen in ESCs and iPSCs, but are also highly tumorigenic in in vivo mouse models. Additionally, these CSCs have been implicated in tumor recurrence and chemoresistance, and when isolated have consistently shown to express the master pluripotency and embryonic stem cell regulating gene Oct4. This article reviews the involvement of Oct4 in cancer progression and chemoresistance, with emphasis on ovarian cancer. Overall, we highlight why ovarian cancer patients, who initially respond to conventional chemotherapy subsequently relapse with recurrent chemoresistant disease that is essentially incurable.

MiR-24 regulates the proliferation and invasion of glioma by ST7L via β-catenin/Tcf-4 signaling

MicroRNAs are strongly implicated as affecting glioma, but their specific roles and functions have yet to be fully elucidated. In this study, we defined the expression and function of miR-24, which we found to be upregulated in glioma samples and glioma cells by qRT-PCR. Downregulation of miR-24 in glioma cell lines inhibited proliferation and invasion and induced apoptosis. Using computational and expression analysis, ST7L was identified as a candidate target of miR-24. A reporter assay with the 3'UTR of ST7L cloned downstream of a luciferase gene showed increased luciferase activity in the absence of miR-24, providing strong evidence that miR-24 is a direct regulator of ST7L. Furthermore, we observed that restoration of ST7L activity resulted in effects that were similar to those from transfecting a miR-24 inhibitor into glioma cells. Mechanistic investigation revealed that the deletion of miR-24 suppressed β-catenin/Tcf-4 transcription activity by targeting ST7L. In conclusion, our study demonstrates that miR-24 upregulation is common in glioma and that suppression of miR-24 expression inhibits cell proliferation and invasion, suggesting that miR-24 may act as an oncogene in glioma.

MicroRNA expression in ovarian carcinoma and its correlation with clinicopathological features

Background

MicroRNA (miRNA) expression is known to be deregulated in ovarian carcinomas. However, limited data is available about the miRNA expression pattern for the benign or borderline ovarian tumors as well as differential miRNA expression pattern associated with histological types, grades or clinical stages in ovarian carcinomas. We defined patterns of microRNA expression in tissues from normal, benign, borderline, and malignant ovarian tumors and explored the relationship between frequently deregulated miRNAs and clinicopathologic findings, response to therapy, survival, and association with Her-2/neu status in ovarian carcinomas.

Methods

We measured the expression of nine miRNAs (miR-181d, miR-30a-3p, miR-30c, miR-30d, miR-30e-3p, miR-368, miR-370, miR-493-5p, miR-532-5p) in 171 formalin-fixed, paraffin-embedded ovarian tissue blocks as well as six normal human ovarian surface epithelial (HOSE) cell lines using Taqman-based real-time PCR assays. Her-2/neu overexpression was assessed in ovarian carcinomas (n = 109 cases) by immunohistochemistry analysis.

Results

Expression of four miRNAs (miR-30c, miR-30d, miR-30e-3p, miR-370) was significantly different between carcinomas and benign ovarian tissues as well as between carcinoma and borderline tissues. An additional three miRNAs (miR-181d, miR-30a-3p, miR-532-5p) were significantly different between borderline and carcinoma tissues. Expression of miR-532-5p was significantly lower in borderline than in benign tissues. Among ovarian carcinomas, expression of four miRNAs (miR-30a-3p, miR-30c, miR-30d, miR-30e-3p) was lowest in mucinous and highest in clear cell samples. Expression of miR-30a-3p was higher in well-differentiated compared to poorly differentiated tumors (P = 0.02), and expression of miR-370 was higher in stage I/II compared to stage III/IV samples (P = 0.03). In multivariate analyses, higher expression of miR-181d, miR-30c, miR-30d, and miR-30e-3p was associated with significantly better disease-free or overall survival. Finally, lower expression of miR-30c, miR-30d, miR-30e-3p and miR-532-5p was significantly associated with overexpression of Her-2/neu.

Conclusions

Aberrant expression of miRNAs is common in ovarian tumor suggesting involvement of miRNA in ovarian tumorigenesis. They are associated with histology, clinical stage, survival and oncogene expression in ovarian carcinoma.

MicroRNA-200a and -200b mediated hepatocellular carcinoma cell migration through the epithelial to mesenchymal transition markers

BACKGROUND

MicroRNAs (miRNAs) play an essential role in mediating gene expression in both normal and malignant cells. However, little is known about specific miRNAs during the development of hepatocellular carcinoma (HCC) from well-differentiated to poorly differentiated cells.

METHODS

We performed miRNA array analysis of three different HCC cell lines: HepG2, HepJ5, and skHep-1. The expression patterns of miR-200 family members were confirmed by real-time polymerase chain reaction (PCR). We overexpressed miR-200 family members by using a lentivirus system and selected for stably transduced cells using antibiotics. The migration ability of the cells was tested using the Transwell migration assay system.

RESULTS

Our miRNA array and real-time PCR results indicated a decrease in the expression of miR-200 family members in poorly differentiated skHep-1 cells compared with well-differentiated HepG2 cells. We overexpressed miR-200a and miR-200b in both HepJ5 and skHep-1 cells and found that the overexpression of the miR-200 family members did not influence proliferation, although migration was decreased in these cells. We found that overexpression of miR-200 family members led to an upregulation of E-cadherin expression in both HepJ5 and skHep-1 cells. Furthermore, we silenced E-cadherin expression by shRNA in miR200a-HepJ5 cells and found that the migratory ability of these cells was enhanced upon the decrease in E-cadherin expression.

CONCLUSIONS

Members of the miR-200 family (miR-200a and miR-200b) play important roles in HCC migration by regulating E-cadherin expression.

Prognostic biomarkers in ovarian cancer

Epithelial ovarian cancer (EOC) remains the most lethal gynecological malignancy despite several decades of progress in diagnosis and treatment. Taking advantage of the robust development of discovery and utility of prognostic biomarkers, clinicians and researchers are developing personalized and targeted treatment strategies. This review encompasses recently discovered biomarkers of ovarian cancer, the utility of published prognostic biomarkers for EOC (especially biomarkers related to angiogenesis and key signaling pathways), and their integration into clinical practice.

miRNA-125b regulates TNF-α production in CD14+ neonatal monocytes via post-transcriptional regulation

Neonates, although deficient in cell immunity, frequently reveal sepsis with augmented proinflammatory reactions. Here, we found that neonatal monocytes produced significantly higher TNF-α mRNA and protein than adult monocytes. Assessment of the transcriptional factor found no significant difference of NF-κB p65 level between neonatal and adult monocytes. Addition of Act D to access the half-life of TNF-α mRNA revealed no significant difference of the LPS-induced TNF-α mRNA half-life between them, whereas CHX increased neonatal TNF-α mRNA significantly. This suggests that a post-transcriptional mechanism involves the augmentation of TNF-α production by neonatal monocytes. To examine whether miRNA was involved in the post-transcriptional regulation, differential displays of miRNA array between neonatal and adult MNCs were performed, along with the discovery of hsa-miR-103, hsa-miR-125b, hsa-miR-130a, hsa-miR-454-3p, and hsa-miR-542-3p, which were greater than a twofold decrease or increase after LPS treatment for 4 h. The functional validation identified that miR-125b decreased significantly in association with higher TNF-α expression by neonatal monocytes after LPS stimulation. Transfection of the miR-125b precursor into neonatal monocytes significantly repressed the TNF-α mRNA and protein expression, suggesting that miR-125b negatively regulates TNF-α expression in neonatal monocytes. Modulation of miRNA expression may be used to regulate TNF-α production in newborns with altered proinflammatory reactions.

Prognostic implications of microRNA-100 and its functional roles in human epithelial ovarian cancer

Dysregulation of microRNAs (miRNAs) has been found to be associated with a variety of diseases, including epithelial ovarian cancer (EOC). Recently, miR-100 was reported to be downregulated in human ovarian carcinoma, however, the clinical significance and functional roles of miR-100 expression in human EOC are unclear. TaqMan real-time quantitative RT-PCR assay was performed to detect the expression of miR-100 in 98 EOC tissues and 15 adjacent normal epithelial tissues. The relationship between miR-100 expression and clinicopathological factors in 98 EOC patients was statistically analyzed. The effect of miR-100 expression on patient survival was determined. Finally, the role of miR-100 in EOC cell growth and its possible mechanisms were analyzed with miR-100 precursor or inhibitor-transfected cells. We showed that the level of miR-100 was significantly lower in EOC tissues compared to adjacent normal tissues. Low miR-100 expression was found to be closely correlated with advanced FIGO stage, higher serum CA125 expression level and lymph node involvement. Also, low miR-100 expression was correlated with shorter overall survival of EOC patients, and multivariate analysis showed that the status of miR-100 expression was an independent predictor of overall survival in EOC. Additionally, miR-100 could affect the growth of EOC cells by post-transcriptionally regulating polo-like kinase 1 (PLK1) expression. Together, these results suggest that low miR-100 expression may be an independent poor prognostic factor and miR-100 can function as a tumor suppressor by targeting PLK1 in human EOCs.