An integrated analysis of miRNA and gene copy numbers in xenografts of Ewing's sarcoma

Oncomeric Profiles of microRNAs as New Therapeutic Targets for Treatment of Ewing's Sarcoma: A Composite Review

Ewing's sarcoma is a rare type of cancer that forms in bones and soft tissues in the body, affecting mostly children and young adults. Current treatments for ES are limited to chemotherapy and/or radiation, followed by surgery. Recently, microRNAs have shown favourable results as latent diagnostic and prognostic biomarkers in various cancers. Furthermore, microRNAs have shown to be a good therapeutic agent due to their involvement in the dysregulation of various molecular pathways linked to tumour progression, invasion, angiogenesis, and metastasis. In this review, comprehensive data mining was employed to explore various microRNAs that might have therapeutic potential as target molecules in the treatment of ES.

Hypoxia and HIFs in Ewing sarcoma: new perspectives on a multi-facetted relationship

Hypoxia develops during the growth of solid tumors and influences tumoral activity in multiple ways. Low oxygen tension is also present in the bone microenvironment where Ewing sarcoma (EwS) - a highly aggressive pediatric cancer - mainly arises. Hypoxia inducible factor 1 subunit alpha (HIF-1-a) is the principal molecular mediator of the hypoxic response in cancer whereas EWSR1::FLI1 constitutes the oncogenic driver of EwS. Interaction of the two proteins has been shown in EwS. Although a growing body of studies investigated hypoxia and HIFs in EwS, their precise role for EwS pathophysiology is not clarified to date. This review summarizes and structures recent findings demonstrating that hypoxia and HIFs play a role in EwS at multiple levels. We propose to view hypoxia and HIFs as independent protagonists in the story of EwS and give a perspective on their potential clinical relevance as prognostic markers and therapeutic targets in EwS treatment.

miR-557 suppressed the malignant behaviours of osteosarcoma cells by reducing HOXB9 and deactivating the EMT process

MicroRNAs (miRNAs) are vital gene regulators, which play a profound role in the process of forming and developing many diseases, especially tumour. The study intends to excavate the potential regulatory mechanisms of miR-557 and its targeting gene Homeobox B9 (HOXB9) in osteosarcoma. GEO dataset on osteosarcoma was applied to detect the expression of miR-557 and HOXB9. Associations between miR-557 and HOXB9 were speculated by prediction software and verified by dual luciferase assay. Cell proliferation, colony formation and mobility were measured by cell counting kit-8, plate clone formation and transwell assays. Expression of mesenchymal transitions (MTs) related proteins was assessed by western blot analysis. Low expression of miR-557 was presented in osteosarcoma tissues and cell lines. Upregulation of miR-557 restrained osteosarcoma cells proliferation, movement and MT process. HOXB9, served as a target gene of miR-557, was highly expressed in osteosarcoma, and its high expression was associated with poor prognosis in patients with osteosarcoma. In addition, overexpression of HOXB9 attenuated the inhibitory effects of miR-557 on tumour progression by MT process. Overexpression of miR-557 suppressed the growth, metastasis and MT process of osteosarcoma cells by targeting HOXB9, affording novel molecular selection for targeted therapy of osteosarcoma.

The role of microRNAs in the osteogenic and chondrogenic differentiation of mesenchymal stem cells and bone pathologies

Mesenchymal stem cells (MSCs) have been identified in many adult tissues. MSCs can regenerate through cell division or differentiate into adipocytes, osteoblasts and chondrocytes. As a result, MSCs have become an important source of cells in tissue engineering and regenerative medicine for bone tissue and cartilage. Several epigenetic factors are believed to play a role in MSCs differentiation. Among these, microRNA (miRNA) regulation is involved in the fine modulation of gene expression during osteogenic/chondrogenic differentiation. It has been reported that miRNAs are involved in bone homeostasis by modulating osteoblast gene expression. In addition, countless evidence has demonstrated that miRNAs dysregulation is involved in the development of osteoporosis and bone fractures. The deregulation of miRNAs expression has also been associated with several malignancies including bone cancer. In this context, bone-associated circulating miRNAs may be useful biomarkers for determining the predisposition, onset and development of osteoporosis, as well as in clinical applications to improve the diagnosis, follow-up and treatment of cancer and metastases. Overall, this review will provide an overview of how miRNAs activities participate in osteogenic/chondrogenic differentiation, while addressing the role of miRNA regulatory effects on target genes. Finally, the role of miRNAs in pathologies and therapies will be presented.

Genome-wide identification and functional prediction of circular RNAs in response to heat stress in Chinese Holstein cows

Heat stress (HS) leads to substantial economic loss of dairy industry each year. The negative effect of HS in dairy cows is becoming one of the more urgent issue due to accelerating side-effects of global warming. Various genes are involved in HS response but the information about the role of noncoding RNAs, especially circular RNAs (circRNAs) is largely unknown. In our study, we aimed to investigate the different expression profile of circRNAs between HS and Non-heat-stressed condition (NC) of Chinese Holstein cow's mammary gland. CircRNAs were identified using RNA sequencing and bioinformatics analysis. In total, 37405 circRNAs were detected and 95 were differentially expressed (DE), including 15 downregulated and 80 upregulated circRNAs in HS group compared to NC. Eight circRNAs were randomly selected to verify the RNA sequencing result. Further, Sanger sequencing validated the backsplicing site of the eight circRNAs. Moreover, results obtained from the Quantitative real time PCR (qRT-PCR) showed consistent expression trend with that of RNA sequencing. GO annotation and KEGG analysis suggested that these DE circRNAs probably involved in the energy metabolic regulation. Furthermore, we constructed ceRNA network and the result indicated that these DE circRNAs could regulate lactation through IGF1 and PRL signaling pathway.

A novel prognostic model based on four circulating miRNA in diffuse large B-cell lymphoma: implications for the roles of MDSC and Th17 cells in lymphoma progression

MicroRNA (miRNA) have been emerged as prognostic biomarkers in diffuse large B-cell lymphoma (DLBCL). To understand the potential underlying mechanisms and translate these findings into clinical prediction on lymphoma progression, large patient cohorts should be evaluated. Here, using miRNA PCR array, we analyzed the miRNA expression profiles in serum samples of 20 DLBCL patients at diagnosis, remission and relapse. Four candidate miRNA were identified and subsequently evaluated for their ability to predict relapse and survival. A prognostic model based on four circulating miRNA (miR21, miR130b, miR155 and miR28) was established and tested in a training cohort of 279 patients and in a validation cohort of 225 patients (NCT01852435). The prognostic value of the 4-circulating miRNA model was assessed by univariate and multivariate analyses. The novel 4-circulating miRNA prognostic model significantly predicted clinical outcome of DLBCL, independent of International Prognostic Index in the training cohort [hazard ratio (HR) = 2.83, 95% CI 2.14-3.51, P < 0.001] and in the validation cohort (HR = 2.71, 95% CI 1.91-3.50, P < 0.001). Moreover, DNA- and RNA-sequencing was performed on tumor samples to detect genetic mutations and signaling pathway dysregulation. DNA-sequencing data showed no significant difference of tumor mutation burden between the low-risk and the high-risk groups of the 4-circulating miRNA model. RNA-sequencing revealed a correlation between the 4-circulating miRNA model and aberrant Ras protein signaling transduction. The impact of the miRNA signature on oncogenic signaling and tumor microenvironment was analyzed in vitro and in vivo. In B-lymphoma cells, modulation of the miRNA regulated IGF1 and JUN expression, thereby altering MDSC and Th17 cells. In DLBCL patients, the high-risk group presented Ras signaling activation, increased MDSC and Th17 cells, and immunosuppressive status compared with the low-risk group. In conclusion, the easy-to-use 4-circulating miRNA prognostic model effectively predicted relapse and survival in DLBCL. Moreover, the tumor microenvironment contributes to the role of the 4-circulating miRNA model in DLBCL progression.

Elevated Levels of circRUNX1 in Colorectal Cancer Promote Cell Growth and Metastasis via miR-145-5p/IGF1 Signalling

Background

Emerging evidence suggests that circular RNAs (circRNAs) are vital regulators in a range of cancers. “miRNA sponge” is the most reported role played by circRNAs in many tumors. The insulin-like growth factor (IGF) 1 pathway plays a key role in the development and progression of many cancers, including colorectal cancer (CRC). The aim of the study is to establish the potential clinical value and driving molecular mechanisms of circRNAs in CRC.

Materials and Methods

Real-time quantitative RT-PCR (qRT-PCR) was performed to measure the circRUNX1 expression in 52 tissue samples from CRC patients. We verified the tumor promotor role of circRUNX1 in cell-based in vitro and in vivo assays. Human growth factor array was used to identify circRUNX1-regulated signaling pathways. We then used a double luciferase reporter assay and RNA fluorescence in situ hybridization to identify the downstream miR-145-5p of circRUNX1. Furthermore, we performed Western blotting and biological function assays to demonstrate if the circRUNX1/miR-145-5p/IGF1 axis is responsible for the proliferation of CRC cells and promotes CRC development.

Results

By performing qRT-PCR from CRC tissues and paired adjacent normal mucosa tissues, we identified that circRUNX1 expression was significantly upregulated in CRC tissues and positively related with lymph node metastasis, distant metastasis and advanced tumor-node-metastasis tumor stage in patients. Functionally, circRUNX1 knockdown inhibited cell proliferation and migration and promoted apoptosis, whereas its overexpression exerted opposite effects. In vivo, circRUNX1 promoted tumor growth and metastasis. Mechanically, circRUNX1 shared miRNA response elements with IGF1. circRUNX1 competitively bound to miR-145-5p and prevented miR-145-5p from decreasing the expression of IGF1, which facilitated tumor growth.

Conclusion

Our studies verified that circRUNX1 functions as a tumor promotor in CRC cells by targeting the miR-145-5p/IGF1 signaling pathway and may have potential use as a prognostic indicator and therapeutic target in CRC patients.

miRNA signatures in childhood sarcomas and their clinical implications

Progresses in multimodal treatments have significantly improved the outcomes for childhood cancer. Nonetheless, for about one-third of patients with Ewing sarcoma, rhabdomyosarcoma, or osteosarcoma steady remission has remained intangible. Thus, new biomarkers to improve early diagnosis and the development of precision-targeted medicine remain imperative. Over the last decade, remarkable progress has been made in the basic understanding of miRNAs function and in interpreting the contribution of their dysregulation to cancer development and progression. On this basis, this review focuses on what has been learned about the pivotal roles of miRNAs in the regulation of key genes implicated in childhood sarcomas.

miR-557 inhibits the proliferation and invasion of pancreatic cancer cells by targeting EGFR

Deregulation of microRNA has been suggested as a critical event in pancreatic cancer development and progression. Thus far, very little is known about the role of miR-557; therefore, the goal of this study was to investigate the potential role of miR-557 in pancreatic cancer. In the present study, we discovered that miR-557 expression was lowered in cancerous pancreatic tissue samples relative to non-cancerous adjacent controls, and when miR-557 was overexpressed we found that this promoted the apoptotic death of pancreatic cancer cells, suppressing their proliferation, invasion, and migration. Using western blotting and luciferase reporter assays, we further found evidence that this miRNA may directly suppress expression of the epidermal growth factor receptor via suppressing its translation through 3'-UTR binding. When EGFR was overexpressed in our pancreatic cancer cells, this was sufficient to reverse the effects of miR-557 inhibition. In summary, miR-557 acts as a tumor suppressor in pancreatic cancer cells, impairing their ability to grow and invade surrounding tissues due at least in part to EGFR inhibition. Harnessing this targeting of EGFR via this miRNA may therefore be a viable strategy useful for patient suffering from this deadly disease.

Translocations involving ETS family proteins in human cancer

The ETS transcription factors regulate expression of genes involved in normal cell development, proliferation, differentiation, angiogenesis, and apoptosis, consisting of 28 family members in humans. Dysregulation of these transcription factors facilitates cell proliferation in cancers, and several members participate in invasion and metastasis by activating certain gene transcriptions. ETS1 and ETS2 are the founding members of the ETS family and regulate transcription by binding to ETS sequences. Three chimeric genes involving ETS genes have been identified in human cancers, which are EWS-FLI1 in Ewing's sarcoma, TMPRSS2-ERG in prostate cancer, and ETV6-RUNX1 in acute lymphocytic leukemia. Although these fusion transcripts definitely contribute to the pathogenesis of the disease, the impact of these fusion transcripts on patients' prognosis is highly controversial. In the present review, the roles of ETS protein translocations in human carcinogenesis are discussed.

miR-598 acts as a tumor suppressor in human gastric cancer by targeting IGF-1R

Background

In recent years, the aberrant expression of miR-598 in tumorigenesis has been demonstrated, as well as the fact that the IGF-1R pathway is also involved in the development of human gastric cancer (GC). The present study aimed to investigate the molecular mechanisms underlying miR-598-regulated IGF-1R expression in human GC.

Materials and methods

We analyzed the expression of miR-598 and IGF-1R in GC samples and cells, and evaluated the clinical significance of miR-598 and IGF-1R in GC patients. Furthermore, in vitro and in vivo assays were used to investigate the molecular mechanisms of miR-598 and IGF-1R.

Results

miR-598 expression was frequently downregulated in GC tissues and cells, and significantly correlated with poor prognosis, vascular invasion, TNM stage, and lymph node metastases as well as IGF-1R expression. The overexpression of miR-598 obviously inhibited cell proliferation, migration, invasion, and induced cell cycle arrest in the G1/S phase, and increased the apoptosis of GC cells. The overexpression of miR-598 also significantly inhibited ERK1/2 and Akt phosphorylation level. In vivo assay validated the inhibitory effect of miR-598 on tumor growth. Further studies showed that miR-598 inhibited IGF-1R protein expression by directly targeting its 3′-UTR. Besides, over-expression of IGF-1R reversed the inhibitory effects of miR-598, while suppression of IGF-1R expression showed inverse effects.

Conclusion

miR-598 suppresses GC cell proliferation, migration and invasion by directly targeting IGF-1R expression. Thus, miR-598 may be a useful target for GC patients.

MiR-557 works as a tumor suppressor in human lung cancers by negatively regulating LEF1 expression

MicroRNAs play an important role in regulating post-transcriptional gene expression in the progression of various human cancers. In this study, we investigated the role of microRNA-557 in human lung cancer cells. The molecular mechanism of microRNA-557 was also clarified in the proliferation and invasion of human lung cancer cells. Our results showed microRNA-557 levels were obviously decreased in clinical lung cancer specimens and lung cancer cell lines. Cell viability of A549 and NCI-H460 cells transfected with microRNA-557 mimics was significantly decreased than those transfected with negative control mimics. MicroRNA-557 promoted cell death of A549 and NCI-H460 but did not affect the cell apoptosis of lung cancer cells. Overexpression of microRNA-557 inhibited cell invasion of A549 and NCI-H460 cells. TargetScan analysis showed that microRNA-557 might target 3' untranslated region of lymphocyte enhancement factor 1, and the western blotting results showed that transfection of microRNA-557 mimics significantly decreased the levels of lymphocyte enhancement factor 1 in A549 and H460 cells. MicroRNA-557 might work as a tumor suppressor by negatively regulating the expression of lymphocyte enhancement factor 1 in lung cancer cells.

Ewing's Sarcoma: An Analysis of miRNA Expression Profiles and Target Genes in Paraffin-Embedded Primary Tumor Tissue

The molecular mechanism responsible for Ewing’s Sarcoma (ES) remains largely unknown. MicroRNAs (miRNAs), a class of small non-coding RNAs able to regulate gene expression, are deregulated in tumors and may serve as a tool for diagnosis and prediction. However, the status of miRNAs in ES has not yet been thoroughly investigated. This study compared global miRNAs expression in paraffin-embedded tumor tissue samples from 20 ES patients, affected by primary untreated tumors, with miRNAs expressed in normal human mesenchymal stromal cells (MSCs) by microarray analysis. A miRTarBase database was used to identify the predicted target genes for differentially expressed miRNAs. The miRNAs microarray analysis revealed distinct patterns of miRNAs expression between ES samples and normal MSCs. 58 of the 954 analyzed miRNAs were significantly differentially expressed in ES samples compared to MSCs. Moreover, the qRT-PCR analysis carried out on three selected miRNAs showed that miR-181b, miR-1915 and miR-1275 were significantly aberrantly regulated, confirming the microarray results. Bio-database analysis identified BCL-2 as a bona fide target gene of the miR-21, miR-181a, miR-181b, miR-29a, miR-29b, miR-497, miR-195, miR-let-7a, miR-34a and miR-1915. Using paraffin-embedded tissues from ES patients, this study has identified several potential target miRNAs and one gene that might be considered a novel critical biomarker for ES pathogenesis.

The SOX17/miR-371-5p/SOX2 axis inhibits EMT, stem cell properties and metastasis in colorectal cancer

Cancer stem cells (CSCs) and EMT-type cells, which share molecular characteristics with CSCs, have been believed to play critical roles in tumor metastasis. Although much progress has been garnered in elucidating the molecular pathways that trigger EMT, stemness and metastasis, a number of key mechanistic gaps remain elusive. In the study, miR-371-5p was obviously down-regulated in primary CRC tissues compared with matched adjacent normal mucosa and correlated significantly with differentiation, tumor size, lymphatic and liver metastases. MiR-371-5p could attenuate proliferation, invasion in vitro and metastasis in vivo in CRC cells. It also suppressed EMT by regulating Wnt/β-catenin signaling and strongly decreased the CRC stemness phenotypes. Moreover, demethylation of SOX17 induced miR-371-5p expression and consequently suppressed its direct target SOX2 in CRC cells. MiR-371-5p was necessary for SOX17 mediated cancer-related traits and SOX2 was a functional target of miR-371-5p. A positive relationship between SOX17 and miR-371-5p expression and a negative one between miR-371-5p and SOX2 expression were observed in CRC cell lines and tissues. In conclusion, we identified miR-371-5p as an important “oncosuppressor” in CRC progression and elucidated a novel mechanism of the SOX17/miR-371-5p/SOX2 axis in the regulation of EMT, stemness and metastasis, which may be a potential therapeutic target.

What Do We Know about the Role of miRNAs in Pediatric Sarcoma?

Non-coding RNAs have received a lot of attention in recent years, with especial focus on microRNAs (miRNAs), so much so that in the just over two decades since the first miRNA, Lin4, was described, almost 40,000 publications about miRNAs have been generated. Less than 500 of these focus on sarcoma, and only a fraction of those on sarcomas of childhood specifically, with some of these representing observational studies and others containing functionally validated data. This is a group of cancers for which prognosis is often poor and therapeutic options limited, and it is especially in these areas that strides in understanding the role of non-coding RNAs and miRNAs in particular are to be welcomed. This review deals with the main forms of pediatric sarcoma, exploring what is known about the diagnostic and prognostic profiles of miRNAs in these tumours and where novel therapeutic options might present themselves for further exploration.

EWS/FLI1 Target Genes and Therapeutic Opportunities in Ewing Sarcoma

Ewing sarcoma is an aggressive bone malignancy that affect children and young adults. Ewing sarcoma is the second most common primary bone malignancy in pediatric patients. Although significant progress has been made in the treatment of Ewing sarcoma since it was first described in the 1920s, in the last decade survival rates have remained unacceptably invariable, thus pointing to the need for new approaches centered in the molecular basis of the disease. Ewing sarcoma driving mutation, EWS–FLI1, which results from a chromosomal translocation, encodes an aberrant transcription factor. Since its first characterization in 1990s, many molecular targets have been described to be regulated by this chimeric transcription factor. Their contribution to orchestrate Ewing sarcoma phenotype has been reported over the last decades. In this work, we will focus on the description of a selection of EWS/FLI1 targets, their functional role, and their potential clinical relevance. We will also discuss their role in other types of cancer as well as the need for further studies to be performed in order to achieve a broader understanding of their particular contribution to Ewing sarcoma development.

MicroRNAs as potential target in human bone and soft tissue sarcoma therapeutics

Sarcomas are highly aggressive heterogeneous tumors that are mesenchymal in origin. There have been vast advancements on identifying diagnostic markers for sarcomas including chromosomal translocations, but very little progress has been made to identify targeted therapies against them. The tumor heterogeneity, genetic complexity and the lack of drug studies make it challenging to recognize the potential targets and also accounts for the inadequate treatments in sarcomas. In recent years, microRNAs that are a part of small non-coding RNAs have shown promising results as potential diagnostic and prognostic biomarkers in multiple sarcoma types. This review focuses on the current knowledge of the microRNAs that are deregulated in sarcomas, and an insight on the strategies to target these microRNAs that are essential for developing improved therapies for various human sarcomas.

Role of microRNA-150 in solid tumors

MicroRNAs (miRNAs) are a family of small endogenous noncoding RNAs and their altered expression has been associated with various cellular functions, including cell development, proliferation, differentiation, apoptosis, signal transduction, tumorigenesis and cancer progression. Accumulating evidence has indicated that miRNA (miR)-150 plays an essential regulatory role in normal hematopoiesis and tumorigenesis; therefore, miR-150 may be a potential biomarker and therapeutic target in the diagnosis and treatment of various malignancies. The aim of the present review was to summarize the current knowledge on the functions and regulatory mechanism of miR-150 as an oncogene or tumor suppressor gene in solid tumors. In addition, its potential application as a tumor biomarker, targeted therapeutic strategy and index of prognosis in various cancer types was investigated.

A novel miRNA-based predictive model for biochemical failure following post-prostatectomy salvage radiation therapy

Purpose

To develop a microRNA (miRNA)-based predictive model for prostate cancer patients of 1) time to biochemical recurrence after radical prostatectomy and 2) biochemical recurrence after salvage radiation therapy following documented biochemical disease progression post-radical prostatectomy.

Methods

Forty three patients who had undergone salvage radiation therapy following biochemical failure after radical prostatectomy with greater than 4 years of follow-up data were identified. Formalin-fixed, paraffin-embedded tissue blocks were collected for all patients and total RNA was isolated from 1mm cores enriched for tumor (>70%). Eight hundred miRNAs were analyzed simultaneously using the nCounter human miRNA v2 assay (NanoString Technologies; Seattle, WA). Univariate and multivariate Cox proportion hazards regression models as well as receiver operating characteristics were used to identify statistically significant miRNAs that were predictive of biochemical recurrence.

Results

Eighty eight miRNAs were identified to be significantly (p<0.05) associated with biochemical failure post-prostatectomy by multivariate analysis and clustered into two groups that correlated with early (≤ 36 months) versus late recurrence (>36 months). Nine miRNAs were identified to be significantly (p<0.05) associated by multivariate analysis with biochemical failure after salvage radiation therapy. A new predictive model for biochemical recurrence after salvage radiation therapy was developed; this model consisted of miR-4516 and miR-601 together with, Gleason score, and lymph node status. The area under the ROC curve (AUC) was improved to 0.83 compared to that of 0.66 for Gleason score and lymph node status alone.

Conclusion

miRNA signatures can distinguish patients who fail soon after radical prostatectomy versus late failures, giving insight into which patients may need adjuvant therapy. Notably, two novel miRNAs (miR-4516 and miR-601) were identified that significantly improve prediction of biochemical failure post-salvage radiation therapy compared to clinico-histopathological factors, supporting the use of miRNAs within clinically used predictive models. Both findings warrant further validation studies.

The Role of Immunohistochemistry in Rhabdomyosarcoma Diagnosis Using Tissue Microarray Technology and a Xenograft Model

Rhabdomyosarcomas (RMS) may resemble other non-myogenic sarcomas and malignant rhabdoid tumor (MRT). Alveolar rhabdomyosarcoma (ARMS) often harbors a typical translocation, but embryonal rhabdomyosarcoma (ERMS) lacks any specific rearrangement. Histopathology is not always sufficient for an unequivocal diagnosis, necessitating ancillary studies, including immunohistochemistry (IHC). Sixteen genetically tested RMS and two MRT were xenografted and followed in successive passages. Tissue microarrays were constructed including samples from original and xenograft tumors. Desmin, myogenin, CK, EMA, INI1, LSD1, AP2β, fibrillin-2, HMGA2, nestin, and SIRT1 were tested using immunohistochemical staining. Desmin and myogenin were positive in all RMS, and the epithelial markers were negative in almost all RMS. New markers (LSD1, AP2β, HMGA2, Nestin, and SIRT1) were positive in all RMS and MRT. There were no differences in IHC expression between the three RMS subtypes tested except fibrillin-2, which was negative in ARMS. Applying new IHC markers can contribute to RMS diagnosis. Nevertheless, most markers are also expressed in MRT, and further studies are needed to confirm their value against this and other small round cell tumors.

MicroRNA expression and its clinical implications in Ewing's sarcoma

Ewing's sarcoma (EWS) is the second most common primary bone cancer, and is a predominant childhood malignant disease. Due to limited understanding of its pathogenesis and frequent occurrence of resistance to conventional types of treatment, its management remains difficult, and mortality is frequent. Development of EWS is a multistep process involving genetic and epigenetic alterations of protein-coding proto-oncogenes and tumour-suppressor genes. MicroRNAs (miRNAs) have recently been discovered as a new category of non-protein coding; small RNA molecules that regulate gene expression at the post-transcriptional level. Substantial numbers of deregulated miRNAs have been documented in EWS and their biological significance has been confirmed in multiple functional experiments. Several studies have confirmed involvement of miRNAs in various steps of EWS pathogenesis, from occurrence to metastasis. Functionally, miRNA dysregulation may promote cell-cycle progression, confer resistance to apoptosis, and enhance invasiveness and metastasis. These miRNAs have opened a novel field in cancer research with potential clinical utilization for screening, diagnosis, prognostics and prediction of response to treatment. Elucidating biological aspects of miRNA dysregulation may help better understand pathogenesis of EWS and promote development of miRNA directed-therapeutics against it.

Differentiating soft tissue leiomyosarcoma and undifferentiated pleomorphic sarcoma: A miRNA analysis

The rare and highly aggressive adult soft tissue sarcomas leiomyosarcoma (LMS) and undifferentiated pleomorphic sarcoma (UPS) contain complex genomes characterized by a multitude of rearrangements, amplifications, and deletions. Differential diagnosis remains a challenge. MicroRNA (miRNA) profiling was conducted on a series of LMS and UPS samples to initially investigate the differential expression and to identify specific signatures useful for improving the differential diagnosis. Initially, 10 high-grade LMS and 10 high-grade UPS were profiled with a miRNA microarray. Two cultured human mesenchymal stem cell samples were used as controls. 38 and 46 miRNAs classified UPS and LMS samples, respectively, into separate groups compared to control samples. When comparing the two profiles, miR-199b-5p, miR-320a, miR-199a-3p, miR-126, miR-22 were differentially expressed. These were validated by RT-PCR on a further series of 27 UPS and 21 LMS for a total of 68 cases. The levels of miR-199-5p and miR-320a, in particular, confirmed the microarray data, the former highly expressed in UPS and the latter in LMS. Immunohistochemistry was performed on all 68 cases to confirm original diagnosis. Recently reported LMS- and UPS-associated genes were correlated with miRNA targets based on target algorithms of three databases. Several genes including IMP3, ROR2, MDM2, CDK4, and UPA, are targets of differentially expressed miRNAs. We identified miRNA expression patterns in LMS and UPS, linking them to chromosomal regions and mRNA targets known to be involved in tumor development/progression of LMS and UPS.

Differentially expressed miRNAs in Ewing sarcoma compared to mesenchymal stem cells: low miR-31 expression with effects on proliferation and invasion

Ewing sarcoma, the second most common bone tumor in children and young adults, is an aggressive malignancy with a strong potential to metastasize. Ewing sarcoma is characterised by translocations encoding fusion transcription factors with an EWSR1 transactivation domain fused to an ETS family DNA binding domain. microRNAs are post-transcriptional regulators of gene expression and aberrantly expressed microRNAs have been identified as tumor suppressors or oncogenes in most cancer types. To identify potential oncogenic and tumor suppressor microRNAs in Ewing sarcoma, we determined and compared the expression of 377 microRNAs in 40 Ewing sarcoma biopsies, 6 Ewing sarcoma cell lines and mesenchymal stem cells, the putative cellular origin of Ewing sarcoma, from 6 healthy donors. Of the 35 differentially expressed microRNAs identified (fold change >4 and q<0.05), 19 were higher and 16 lower expressed in Ewing sarcoma. In comparisons between Ewing sarcoma samples with EWS-FLI or EWS-ERG translocations, with differing dissemination characteristics and of primary samples and metastases no significantly differential expressed microRNAs were detected using various stringency criteria. For miR-31, the microRNA with lowest expression in comparison to mesenchymal stem cells, functional analyses were performed to determine its potential as a tumor suppressor in Ewing sarcoma. Two of four miR-31 transfected Ewing sarcoma cell lines showed a significantly reduced proliferation (19% and 33% reduction) due to increased apoptosis in one and increased length of G1-phase in the other cell line. All three tested miR-31 transfected Ewing sarcoma cell lines showed significantly reduced invasiveness (56% to 71% reduction). In summary, we identified 35 microRNAs differentially expressed in Ewing sarcoma and demonstrate that miR-31 affects proliferation and invasion of Ewing sarcoma cell lines in ex vivo assays.

MicroRNA-mediated gene regulations in human sarcomas

Sarcomas are a heterogeneous group of tumors with mesenchymal origins. Sarcomas are broadly classified into bone and soft tissue sarcomas with over 50 subtypes. Despite recent advances in sarcoma classification and treatment strategies, the prognosis of some aggressive sarcoma types remains poor due to treatment infectiveness and development of drug resistance. A better understanding of sarcoma pathobiology will significantly increase the potential for the development of therapeutics and treatment strategies. Recently, expressions of microRNAs (miRNA), a class of small non-coding RNAs, have been found to be deregulated in many sarcomas and are implicated in sarcoma pathobiology. Comprehensive understanding of gene regulatory networks mediated by miRNAs in each sarcoma type and the conservation of some shared/conserved miRNA-gene networks could be potentially investigated in the prevention, diagnosis, prognosis and as multi-modal treatment options in these cancers. In this review, we will discuss the current knowledge of miRNA-gene regulatory networks in various sarcoma types and give a perspective of the complex multilayer miRNA-mediated gene regulation in sarcomas.