The muscle-specific microRNA miR-206 blocks human rhabdomyosarcoma growth in xenotransplanted mice by promoting myogenic differentiation

MicroRNAs and angiosarcoma: are there promising reports?

In recent years, microRNAs (miRNAs) have garnered increasing attention for their potential implications in cancer pathogenesis, functioning either as oncogenes or tumor suppressors. Notably, angiosarcoma, along with various other cardiovascular tumors such as lipomas, rhabdomyomas, hemangiomas, and myxomas, has shown variations in the expression of specific miRNA subtypes. A substantial body of evidence underscores the pivotal involvement of miRNAs in the genesis of angiosarcoma and certain cardiovascular tumors. This review aims to delve into the current literature on miRNAs and their prospective applications in cardiovascular malignancies, with a specific focus on angiosarcoma. It comprehensively covers diagnostic methods, prognostic evaluations, and potential treatments while providing a recapitulation of angiosarcoma's risk factors and molecular pathogenesis, with an emphasis on the role of miRNAs. These insights can serve as the groundwork for designing randomized control trials, ultimately facilitating the translation of these findings into clinical applications. Moving forward, it is imperative for studies to thoroughly scrutinize the advantages and disadvantages of miRNAs compared to current diagnostic and prognostic approaches in angiosarcoma and other cardiovascular tumors. Closing these knowledge gaps will be crucial for harnessing the full potential of miRNAs in the realm of angiosarcoma and cardiovascular tumor research.

Differentiation-dependent chromosomal organization changes in normal myogenic cells are absent in rhabdomyosarcoma cells

Myogenesis, the progression of proliferating skeletal myoblasts to terminally differentiated myotubes, regulates thousands of target genes. Uninterrupted linear arrays of such genes are differentially associated with specific chromosomes, suggesting chromosome specific regulatory roles in myogenesis. Rhabdomyosarcoma (RMS), a tumor of skeletal muscle, shares common features with normal muscle cells. We hypothesized that RMS and myogenic cells possess differences in chromosomal organization related to myogenic gene arrangement. We compared the organizational characteristics of chromosomes 2 and 18, chosen for their difference in myogenic gene arrangement, in cultured RMS cell lines and normal myoblasts and myotubes. We found chromosome-specific differences in organization during normal myogenesis, with increased area occupied and a shift in peripheral localization specifically for chromosome 2. Most strikingly, we found a differentiation-dependent difference in positioning of chromosome 2 relative to the nuclear axis, with preferential positioning along the major nuclear axis present only in myotubes. RMS cells demonstrated no preference for such axial positioning, but induced differentiation through transfection of the pro-myogenic miRNA miR-206 resulted in an increase of major axial positioning of chromosome 2. Our findings identify both a differentiation-dependent, chromosome-specific change in organization in normal myogenesis, and highlight the role of chromosomal spatial organization in myogenic differentiation.

Extirpating the cancer stem cell hydra: Differentiation therapy and Hyperthermia therapy for targeting the cancer stem cell hierarchy

Ever since the discovery of cancer stem cells (CSCs), they have progressively attracted more attention as a therapeutic target. Like the mythical hydra, this subpopulation of cells seems to contribute to cancer immortality, spawning more cells each time that some components of the cancer cell hierarchy are destroyed. Traditional modalities focusing on cancer treatment have emphasized apoptosis as a route to eliminate the tumor burden. A major problem is that cancer cells are often in varying degrees of dedifferentiation contributing to what is known as the CSCs hierarchy and cells which are known to be resistant to conventional therapy. Differentiation therapy is an experimental therapeutic modality aimed at the conversion of malignant phenotype to a more benign one. Hyperthermia therapy (HT) is a modality exploiting the changes induced in cells by the application of heat produced to aid in cancer therapy. While differentiation therapy has been successfully employed in the treatment of acute myeloid leukemia, it has not been hugely successful for other cancer types. Mounting evidence suggests that hyperthermia therapy may greatly augment the effects of differentiation therapy while simultaneously overcoming many of the hard-to-treat facets of recurrent tumors. This review summarizes the progress made so far in integrating hyperthermia therapy with existing modules of differentiation therapy. The focus is on studies related to the successful application of both hyperthermia and differentiation therapy when used alone or in conjunction for hard-to-treat cancer cell niche with emphasis on combined approaches to target the CSCs hierarchy.

Small Non-Coding RNAs in Soft-Tissue Sarcomas: State of the Art and Future Directions

Soft-tissue sarcomas (STS) are a rare and heterogeneous group of tumors that arise from connective tissue and can occur anywhere in the body. Among the plethora of over 50 different STS types, liposarcoma (LPS) is one of the most common. The subtypes of STS are characterized by distinct differences in tumor biology that drive responses to pharmacologic therapy and disparate oncologic outcomes. Small non-coding RNAs (sncRNA) are a heterogeneous class of regulatory RNAs involved in the regulation of gene expression by targeting mRNAs. Among the several types of sncRNAs, miRNAs and tRNA-derived ncRNAs are the most studied in the context of tumor biology, and we are learning more about the role of these molecules as important regulators of STS tumorigenesis and differentiation. However, challenges remain in translating these findings and no biomarkers or therapeutic approaches targeting sncRNAs have been developed for clinical use. In this review, we summarize the current landscape of sncRNAs in the context of STS with an emphasis on LPS, including the role of sncRNAs in the tumorigenesis and differentiation of these rare malignancies and their potential as novel biomarkers and therapeutic targets. Finally, we provide an appraisal of published studies and outline future directions to study sncRNAs in STS, including tRNA-derived ncRNAs.

Exploring circular MET RNA as a potential biomarker in tumors exhibiting high MET activity

BACKGROUND

MET-driven acquired resistance is emerging with unanticipated frequency in patients relapsing upon molecular therapy treatments. However, the determination of MET amplification remains challenging using both standard and next-generation sequencing-based methodologies. Liquid biopsy is an effective, non-invasive approach to define cancer genomic profiles, track tumor evolution over time, monitor treatment response and detect molecular resistance in advance. Circular RNAs (circRNAs), a family of RNA molecules that originate from a process of back-splicing, are attracting growing interest as potential novel biomarkers for their stability in body fluids.

METHODS

We identified a circRNA encoded by the MET gene (circMET) and exploited blood-derived cell-free RNA (cfRNA) and matched tumor tissues to identify, stratify and monitor advanced cancer patients molecularly characterized by high MET activity, generally associated with genomic amplification.

RESULTS

Using publicly available bioinformatic tools, we discovered that the MET locus transcribes several circRNA molecules, but only one candidate, circMET, was particularly abundant. Deeper molecular analysis revealed that circMET levels positively correlated with MET expression and activity, especially in MET-amplified cells. We developed a circMET-detection strategy and, in parallel, we performed standard FISH and IHC analyses in the same specimens to assess whether circMET quantification could identify patients displaying high MET activity. Longitudinal monitoring of circMET levels in the plasma of selected patients revealed the early emergence of MET amplification as a mechanism of acquired resistance to molecular therapies.

CONCLUSIONS

We found that measurement of circMET levels allows identification and tracking of patients characterized by high MET activity. Circulating circMET (ccMET) detection and analysis could be a simple, cost-effective, non-invasive approach to better implement patient stratification based on MET expression, as well as to dynamically monitor over time both therapy response and clonal evolution during treatment.

Differentiation-dependent chromosomal organization changes in normal myogenic cells are absent in rhabdomyosarcoma cells

Myogenesis, the progression of proliferating skeletal myoblasts to terminally differentiated myotubes, regulates thousands of target genes. Uninterrupted linear arrays of such genes are differentially associated with specific chromosomes, suggesting chromosome specific regulatory roles in myogenesis. Rhabdomyosarcoma (RMS), a tumor of skeletal muscle, shares common features with normal muscle cells. We hypothesized that RMS and myogenic cells possess differences in chromosomal organization related to myogenic gene arrangement. We compared the organizational characteristics of chromosomes 2 and 18, chosen for their difference in myogenic gene arrangement, in cultured RMS cell lines and normal myoblasts and myotubes. We found chromosome-specific differences in organization during normal myogenesis, with increased area occupied and a shift in peripheral localization specifically for chromosome 2. Most strikingly, we found a differentiation-dependent difference in positioning of chromosome 2 relative to the nuclear axis, with preferential positioning along the major nuclear axis present only in myotubes. RMS cells demonstrated no preference for such axial positioning, but induced differentiation through transfection of the pro-myogenic miRNA miR-206 resulted in an increase of major axial positioning of chromosome 2. Our findings identify both a differentiation-dependent, chromosome-specific change in organization in normal myogenesis, and highlight the role of chromosomal spatial organization in myogenic differentiation.

Effect of heme oxygenase-1 on the differentiation of human myoblasts and the regeneration of murine skeletal muscles after acute and chronic injury

BACKGROUND

Impaired muscle regeneration is a hallmark of Duchenne muscular dystrophy (DMD), a neuromuscular disorder caused by mutations in the DMD gene encoding dystrophin. The lack of heme oxygenase-1 (HO-1, Hmox1), a known anti-inflammatory and cytoprotective enzyme, was shown to aggravate DMD pathology.

METHODS

We evaluated the role of HO-1 overexpression in human induced pluripotent stem cell (hiPSC)-derived skeletal muscle cells (hiPSC-SkM) in vitro and in the regeneration process in vivo in wild-type mice. Furthermore, the effect of cobalt protoporphyrin IX (CoPP), a pharmacological inducer of HO-1 expression, on regeneration markers during myogenic hiPSC differentiation and progression of the dystrophic phenotype was analysed in the mdx mouse DMD model.

RESULTS

HO-1 has an impact on hiPSC-SkM generation by decreasing cell fusion capacity and the expression of myogenic regulatory factors and muscle-specific microRNAs (myomiRs). Also, strong induction of HO-1 by CoPP totally abolished hiPSC-SkM differentiation. Injection of HO-1-overexpressing hiPSC-SkM into the cardiotoxin (CTX)-injured muscle of immunodeficient wild-type mice was associated with decreased expression of miR-206 and Myh3 and lower number of regenerating fibers, suggesting some advanced regeneration. However, the very potent induction of HO-1 by CoPP did not exert any protective effect on necrosis, leukocyte infiltration, fibrosis, myofiber regeneration biomarkers, and exercise capacity of mdx mice.

CONCLUSIONS

In summary, HO-1 inhibits the expression of differentiation markers in human iPSC-derived myoblasts. Although moderate overexpression of HO-1 in the injected myoblast was associated with partially advanced muscle regeneration, the high systemic induction of HO-1 did not improve muscle regeneration. The appropriate threshold of HO-1 expression must be established for the therapeutic effect of HO-1 on muscle regeneration.

MiR-223 Exclusively Impairs In Vitro Tumor Growth through IGF1R Modulation in Rhabdomyosarcoma of Adolescents and Young Adults

Adolescents and young adults (AYA) with rhabdomyosarcoma (RMS) form a subgroup of patients whose optimal clinical management and best possible access to care remain a challenge and whose survival rates lag behind that of children diagnosed with histologically similar tumors. A better understanding of tumor biology that differentiates children (PEDS-) from AYA-RMS could provide critical information and drive new initiatives to improve their final outcome. We investigated the functional role of miRNAs implicated in AYA-RMS development, as they have the potential to lead to discovery of new targets pathways for a more tailored treatment in these age groups of young RMS patients. MiR-223 and miR-486 were observed de-regulated in nine RMS tissues compared to their normal counterparts, yet only miR-223 replacement impaired proliferation and aggressiveness of AYA-RMS cell lines, while inducing apoptosis and determining cell cycle arrest. Interestingly, IGF1R resulted in the direct target of miR-223 in AYA-RMS cells, as demonstrated by IGF1R silencing. Our results highlight an exclusive functional role of miR-223 in AYA-RMS development and aggressiveness.

Non-coding RNA in rhabdomyosarcoma progression and metastasis

Rhabdomyosarcoma (RMS) is a soft tissue sarcoma of skeletal muscle differentiation, with a predominant occurrence in children and adolescents. One of the major challenges facing treatment success is the presence of metastatic disease at the time of diagnosis, commonly associated with the more aggressive fusion-positive subtype. Non-coding RNA (ncRNA) can regulate gene transcription and translation, and their dysregulation has been associated with cancer development and progression. MicroRNA (miRNA) are short non-coding nucleic acid sequences involved in the regulation of gene expression that act by targeting messenger RNA (mRNA), and their aberrant expression has been associated with both RMS initiation and progression. Other ncRNA including long non-coding RNA (lncRNA), circular RNA (circRNA) and ribosomal RNA (rRNA) have also been associated with RMS revealing important mechanistic roles in RMS biology, but these studies are still limited and require further investigation. In this review, we discuss the established roles of ncRNA in RMS differentiation, growth and progression, highlighting their potential use in RMS prognosis, as therapeutic agents or as targets of treatment.

Association between microRNA 671 polymorphisms and the susceptibility to soft tissue sarcomas in a Chinese population

This study evaluated the association between the microRNA (miRNA) gene polymorphisms and the susceptibility to soft tissue sarcomas (STSs). In this case–control study, DNA was extracted from leukocytes in peripheral blood, which was collected from 169 STSs patients and 170 healthy controls. Three SNPs for miR-210, five SNPs for miR-206, two SNPs for miR-485, two SNPs for miR-34b, two SNPs for miR-671, and three SNPs for miR-381 were investigated and genotyped using a Sequenom Mass ARRAY matrix-assisted laser desorption/ionization-time of flight mass spectrometry platform. Unconditional logistic regression analysis was used to analyze the association between miRNA gene polymorphisms and the susceptibility to STSs. The results showed that miR-671 rs1870238 GC + CC (OR = 1.963, 95% CI = 1.258–3.064, P = 0.003) and miR-671 rs2446065 CG + GG (OR =1.838, 95% CI = 1.178–2.868, P = 0.007) may be genetic risk factors for STSs after adjustment for age and smoking. Therefore, this study suggests that individuals carrying the GC + CC genotype for miR-671 rs1870238 or the CG + GG genotype for miR-671 rs2446065 are susceptible to STSs.

A miR-137-XIAP axis contributes to the sensitivity of TRAIL-induced cell death in glioblastoma

Glioblastoma (GBM) is the most lethal primary brain tumor in the central nervous system with limited therapeutic strategies to prolong the survival rate in clinic. TNF-related apoptosis-inducing ligand (TRAIL)-based strategy has been demonstrated to induce cell death in an extensive spectrum of tumor cells, including GBM, while a considerable proportion of malignant cells are resistant to TRAIL-induced apoptosis. MiR-137 is highly expressed in the brain, but significantly decreases with advanced progression of GBM. However, the functional link between miR-137 and TRAIL-induced apoptosis in GBM cells has not been established. Here, GBM cells were transfected with miR-137, and gene expression levels were examined by qRT-PCR and western blot. Apoptotic cells were measured by Annexin-V staining and TUNEL assay. Our data showed that miR-137 sensitizes GBM cells to the TRAIL-mediated apoptosis. Mechanistically, we identified that XIAP is a bona fide target of miR-137, which is essential for miR-137-regulated sensitivity of TRAIL-induced cell death in GBM cells. Finally, in a xenograft model, combined utilization of miR-137 and TRAIL potently suppresses tumor growth in vivo. Collectively, we demonstrate that a miR-137-XIAP axis is required for the sensitivity of TRAIL-induced cell death and shed a light on the avenue for the treatment of GBM.

A Signature of Three microRNAs Is a Potential Diagnostic Biomarker for Glioblastoma

Background:

Glioblastoma is the most common primary malignant neoplasm of the central nervous system. Despite progress in diagnosis and treatment, glioblastoma still has a poor prognosis. This study aimed to examine whether a signature of three candidate miRNAs (i.e. hsa-let-7c-5p, hsa-miR-206-5p, and hsa-miR-1909-5p) can be used as a diagnostic biomarker for distinguishing glioblastoma from healthy brain tissues.

Methods:

In this study, 50 FFPE glioblastoma tissue samples and 50 healthy tissue samples adjacent to tumor were included. The expression of each candidate miRNA (i.e. hsa-let-7c-5p, hsa-miR-206-5p, and hsa-miR-1909-5p) was measured using RT-qPCR. To show the roles of each miRNA and their biological effects on glioblastoma development and clinicopathological characteristics, in silico tools were used. ROC curves were performed to assess the diagnostic accuracy of each miRNA.

Results:

Based on the results, hsa-let-7c-5p and hsa-miR-206-5p were downregulated, while hsa-miR-1909-5p was upregulated in glioblastoma tumors compared to healthy samples. No association was detected between the expression of each candidate miRNA and sex. Except for hsa-let-7c-5p, other miRNAs did not correlate with age status. ROC curve analysis indicated that the signature of candidate miRNAs is a potential biomarker distinguishing between glioblastoma and healthy samples. Only hsa-miR-206-5p suggested the association with poor prognosis in glioblastoma patients.

Conclusion:

Our findings revealed that the signature of three miRNAs is capable of distinguishing glioblastoma tumor and healthy tissues. These results are beneficial for the clinical management of glioblastoma patients.

MET Inhibition Sensitizes Rhabdomyosarcoma Cells to NOTCH Signaling Suppression

Rhabdomyosarcoma (RMS) is a pediatric myogenic soft tissue sarcoma. The Fusion-Positive (FP) subtype expresses the chimeric protein PAX3-FOXO1 (P3F) while the Fusion-Negative (FN) is devoid of any gene translocation. FP-RMS and metastatic FN-RMS are often unresponsive to conventional therapy. Therefore, novel therapeutic approaches are needed to halt tumor progression. NOTCH signaling has oncogenic functions in RMS and its pharmacologic inhibition through γ-secretase inhibitors blocks tumor growth in vitro and in vivo. Here, we show that NOTCH signaling blockade resulted in the up-regulation and phosphorylation of the MET oncogene in both RH30 (FP-RMS) and RD (FN-RMS) cell lines. Pharmacologic inhibition of either NOTCH or MET signaling slowed proliferation and restrained cell survival compared to control cells partly by increasing Annexin V and CASP3/7 activation. Co-treatment with NOTCH and MET inhibitors significantly amplified these effects and enhanced PARP1 cleavage in both cell lines. Moreover, it severely hampered cell migration, colony formation, and anchorage-independent growth compared to single-agent treatments in both cell lines and significantly prevented the growth of FN-RMS cells grown as spheroids. Collectively, our results unveil the overexpression of the MET oncogene by NOTCH signaling targeting in RMS cells and show that MET pathway blockade sensitizes them to NOTCH inhibition.

Terminal differentiation and anti-tumorigenic effects of prolactin in breast cancer

Breast cancer is a major disease affecting women worldwide. A woman has 1 in 8 lifetime risk of developing breast cancer, and morbidity and mortality due to this disease are expected to continue to rise globally. Breast cancer remains a challenging disease due to its heterogeneity, propensity for recurrence and metastasis to distant vital organs including bones, lungs, liver and brain ultimately leading to patient death. Despite the development of various therapeutic strategies to treat breast cancer, still there are no effective treatments once metastasis has occurred. Loss of differentiation and increased cellular plasticity and stemness are being recognized molecularly and clinically as major derivers of heterogeneity, tumor evolution, relapse, metastasis, and therapeutic failure. In solid tumors, breast cancer is one of the leading cancer types in which tumor differentiation state has long been known to influence cancer behavior. Reprograming and/or restoring differentiation of cancer cells has been proposed to provide a viable approach to reverse the cancer through differentiation and terminal maturation. The hormone prolactin (PRL) is known to play a critical role in mammary gland lobuloalveolar development/remodeling and the terminal differentiation of the mammary epithelial cells promoting milk proteins gene expression and lactation. Here, we will highlight recent discoveries supporting an anti-tumorigenic role for PRL in breast cancer as a "pro/forward-differentiation" pathway restricting plasticity, stemness and tumorigenesis.

The hepatocyte growth factor/mesenchymal epithelial transition factor axis in high-risk pediatric solid tumors and the anti-tumor activity of targeted therapeutic agents

Clinical trials completed in the last two decades have contributed significantly to the improved overall survival of children with cancer. In spite of these advancements, disease relapse still remains a significant cause of death in this patient population. Often, increasing the intensity of current protocols is not feasible because of cumulative toxicity and development of drug resistance. Therefore, the identification and clinical validation of novel targets in high-risk and refractory childhood malignancies are essential to develop effective new generation treatment protocols. A number of recent studies have shown that the hepatocyte growth factor (HGF) and its receptor Mesenchymal epithelial transition factor (c-MET) influence the growth, survival, angiogenesis, and metastasis of cancer cells. Therefore, the c-MET receptor tyrosine kinase and HGF have been identified as potential targets for cancer therapeutics and recent years have seen a race to synthesize molecules to block their expression and function. In this review we aim to summarize the literature that explores the potential and biological rationale for targeting the HGF/c-MET pathway in common and high-risk pediatric solid tumors. We also discuss selected recent and ongoing clinical trials with these agents in relapsed pediatric tumors that may provide applicable future treatments for these patients.

βKlotho, a direct target of miR-206, contributes to the growth of hepatoblastoma through augmenting PI3K/Akt/mTOR signaling

Hepatoblastoma (HB) is the most frequent pediatric liver malignancy. However, the treatment outcome for patients with advanced-stage HB remains unsatisfactory. Accumulating evidence indicates that βKlotho (KLB) acts as an oncogene or a tumor-suppressor gene in a context-dependent manner. Despite this, the expression profile and effects of KLB on the growth of HB are still elusive. This study aimed to explore the effect of miR-206/KLB axis on HB growth. The expression of KLB was explored in HB cells (HepG2 and HuH6) and tissues using quantitative polymerase chain reaction (qPCR), Western blot analysis, and immunohistochemistry. Besides, miR-206 expression was determined in HB cells and tissues using qPCR and fluorescence in situ hybridization. The prognostic value of KLB or miR-206 in our patients with HB was investigated using the Kaplan-Meier method. The biological effects of KLB or miR-206 on HB cells were identified in vitro. The proliferative effects of KLB on HuH6 cells were also investigated in vivo. Moreover, the mechanical signaling of KLB in HB was determined through bioinformatics analysis followed by experimental validation. The results showed a significant upregulation of KLB in HB tissues and cells. Elevated level of KLB was found to be significantly correlated with the aggressive phenotype and poor overall survival for children with HB. The in vitro function assay demonstrated that KLB knockdown promoted apoptosis and suppressed the proliferation, migration, and invasion of HB cells. Besides, KLB knockdown inhibited the proliferation of HuH6 cells in vivo, while KLB overexpression had the opposite effect. Furthermore, KLB was proved to be the direct target of miR-206. Low level of miR-206 served as an independent risk factor for poor prognosis in children with HB. The overexpression of miR-206 negatively regulated the aggressive biological behaviors of HB cells, which was partially rescued by KLB overexpression. Mechanically, the miR-206/KLB axis played a vital role in HB growth through augmenting the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling. In conclusion, the data demonstrated that the miR-206/KLB axis might serve as an important biomarker/therapeutic target for HB.

Enhancement of myogenic differentiation and inhibition of rhabdomyosarcoma progression by miR-28-3p and miR-193a-5p regulated by SNAIL

Rhabdomyosarcoma (RMS) is a soft tissue mesenchymal tumor that affects mostly children and adolescents. It originates from the impaired myogenic differentiation of stem cells or early progenitors. SNAIL, a transcription factor that regulates epithelial-to-mesenchymal transition in tumors of epithelial origin, is also a key regulator of RMS growth, progression, and myogenic differentiation. Here, we demonstrate that the SNAIL-dependent microRNAs (miRNAs) miR-28-3p and miR-193a-5p are crucial regulators of RMS growth, differentiation, and progression. miR-28-3p and miR-193a-5p diminished proliferation and arrested RMS cells in G0/G1 phase in vitro. They induced the myogenic differentiation of both RMS cells and human myoblasts by upregulating myogenic factors. Furthermore, miR-28-3p and miR-193a-5p inhibited migration in a scratch assay, adhesion to endothelial cells, chemotaxis, and invasion toward SDF-1 and HGF and regulated angiogenic capabilities of the cells. Overexpression of miR-28-3p and miR-193a-5p induced formation of fibrotic structures and abnormal blood vessels in RMS xenografts in immunodeficient mice in vivo. Simultaneous overexpression of both miRNAs diminished tumor growth after subcutaneous implantation and inhibited the engraftment of RMS cells into bone marrow after intravenous injection in vivo. To conclude, we discovered novel SNAIL-dependent miRNAs that may become new therapeutic targets in RMS in the future.

FAK Signaling in Rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of children and adolescents. The fusion-positive (FP)-RMS variant expressing chimeric oncoproteins such as PAX3-FOXO1 and PAX7-FOXO1 is at high risk. The fusion negative subgroup, FN-RMS, has a good prognosis when non-metastatic. Despite a multimodal therapeutic approach, FP-RMS and metastatic FN-RMS often show a dismal prognosis with 5-year survival of less than 30%. Therefore, novel targets need to be discovered to develop therapies that halt tumor progression, reducing long-term side effects in young patients. Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that regulates focal contacts at the cellular edges. It plays a role in cell motility, survival, and proliferation in response to integrin and growth factor receptors’ activation. FAK is often dysregulated in cancer, being upregulated and/or overactivated in several adult and pediatric tumor types. In RMS, both in vitro and preclinical studies point to a role of FAK in tumor cell motility/invasion and proliferation, which is inhibited by FAK inhibitors. In this review, we summarize the data on FAK expression and modulation in RMS. Moreover, we give an overview of the approaches to inhibit FAK in both preclinical and clinical cancer settings.

Synthetic MIR143-3p Suppresses Cell Growth in Rhabdomyosarcoma Cells by Interrupting RAS Pathways Including PAX3-FOXO1

Simple Summary

Rhabdomyosarcoma (RMS) is a soft tissue sarcoma with embryonal (ERMS) and alveoral (ARMS) features, most frequently found in children. ARMS has the worse prognosis due to the formation of the chimeric PAX3–FOXO1 gene. New therapies are needed for the treatment of ARMS. The aim of this study is to evaluate the anticancer effect of chemically-modified MIR143-3p#12 (CM-MIR143#12) on RMS. The ectopic expression of CM-MIR143#12 induced a cell growth suppression by silencing not only KRAS, AKT, and ERK but also the PAX3–FOXO1 chimeric gene, and KRAS networks could control the expression of chimeric PAX3–FOXO1 in ARMS cells. Moreover, CM-MIR143#12 also silenced NRAS mutant in ERMS RD cells. CM-MIR143#12 can be a new nucleic acid medicine for the treatment of RMS by impairing the RAS networks including PAX3–FOXO1.

Abstract

Rhabdomyosarcoma (RMS) is a soft tissue sarcoma most frequently found in children. In RMS, there are two major subtypes, embryonal RMS (ERMS) and alveolar RMS (ARMS). ARMS has the worse prognosis of the two owing to the formation of the chimeric PAX3–FOXO1 gene. A novel therapeutic method is required for treating ARMS. In our previous study, we found that the ectopic expression of chemically modified MIR143-3p#12 (CM-MIR143#12), which is RNase-resistant and shows the highest anti-proliferation activity among the synthesized MIR143 derivatives that were tested, induces significant cell growth suppression by targeting KRAS, AKT, and ERK in colorectal cancer cells. The expression of MIR143-3p in RMS was dramatically downregulated compared with that of normal tissue. Ectopic expression of CM-MIR143#12 in RMS cells resulted in a significant growth inhibitory effect through the induction of apoptosis and autophagy. Interestingly, we found that CM-MIR143#12 also silenced the expression of chimeric PAX3–FOXO1 directly and, using siR-KRAS or siR-AKT, that KRAS networks regulated the expression of PAX3–FOXO1 in ARMS cells. In ERMS harboring NRAS mutation, CM-MIR143#12 silenced mutated NRAS. These findings indicate that CM-MIR143#12 efficiently perturbed the RAS signaling pathway, including the ARMS-specific KRAS/PAX3–FOXO1 networks.

Participation of MicroRNAs in the Treatment of Cancer with Phytochemicals

Cancer is a global health concern and one of the main causes of disease-related death. Even with considerable progress in investigations on cancer therapy, effective anti-cancer agents and regimens have thus far been insufficient. There has been compelling evidence that natural phytochemicals and their derivatives have potent anti-cancer activities. Plant-based anti-cancer agents, such as etoposide, irinotecan, paclitaxel, and vincristine, are currently being applied in medical treatments for patients with cancer. Further, the efficacy of plenty of phytochemicals has been evaluated to discover a promising candidate for cancer therapy. For developing more effective cancer therapy, it is required to apprehend the molecular mechanism deployed by natural compounds. MicroRNAs (miRNAs) have been realized to play a pivotal role in regulating cellular signaling pathways, affecting the efficacy of therapeutic agents in cancer. This review presents a feature of phytochemicals with anti-cancer activity, focusing mainly on the relationship between phytochemicals and miRNAs, with insights into the role of miRNAs as the mediators and the regulators of anti-cancer effects of phytochemicals.

CDK9 as a Valuable Target in Cancer: From Natural Compounds Inhibitors to Current Treatment in Pediatric Soft Tissue Sarcomas

Cyclin-Dependent Kinases (CDKs) are well-known reliable targets for cancer treatment being often deregulated. Among them, since the transcription-associated CDK9 represents the sentry of cell transcriptional homeostasis, it can be a valuable target for managing cancers in which the transcriptional machinery is dysregulated by tumor-driver oncogenes. Here we give an overview of some natural compounds identified as CDK inhibitors with reported activity also against CDK9, that were taken as a model for the development of highly active synthetic anti-CDK9 agents. After, we summarize the data on CDK9 inhibition in a group of rare pediatric solid tumors such as rhabdomyosarcoma, Ewing’s sarcoma, synovial sarcoma and malignant rhabdoid tumors (soft tissue sarcomas), highlighting the more recent results in this field. Finally, we discuss the perspective and challenge of CDK9 modulation in cancer.

miR-16 integrates signal pathways in myofibroblasts: determinant of cell fate necessary for fibrosis resolution

Liver fibrosis is characterized by the transdifferentiation of hepatic stellate cells (HSCs) to myofibroblasts and poor response to treatment. This can be attributed to the myofibroblast-specific resistance to phenotype reversal. In this study, we complemented miR-16 into miR-16-deficient myofibroblasts and analyzed the global role of miR-16 using transcriptome profiling and generating a pathway-based action model underlying transcriptomic regulation. Phenotypic analysis of myofibroblasts and fibrogenic characterization were used to understand the effect of miR-16 on phenotypic remodeling of myofibroblasts. miR-16 expression altered the transcriptome of myofibroblasts to resemble that of HSCs. Simultaneous targeting of Smad2 and Wnt3a, etc. by miR-16 integrated signaling pathways of TGF-β and Wnt, etc., which underlay the comprehensive regulation of transcriptome. The synergistic effect of miR-16 on the signaling pathways abolished the phenotypic characteristics of myofibroblasts, including collagen production and inhibition of adipogenesis. In vivo, myofibroblast-specific expression of miR-16 not only eliminated mesenchymal cells with myofibroblast characteristics but also restored the phenotype of HSCs in perisinusoidal space. This phenotypic remodeling resolved liver fibrosis induced by chronic wound healing. Therefore, miR-16 may integrate signaling pathways crucial for the fate determination of myofibroblasts. Its global effect induces the reversal of HSC-to-myofibroblast transdifferentiation and, subsequently, the resolution of fibrogenesis. Taken together, these findings highlight the potential of miR-16 as a promising therapeutic target for liver fibrosis.

Transcriptome Characterization of Repressed Embryonic Myogenesis Due to Maternal Calorie Restriction

Fetal malnutrition decreases skeletal myofiber number and muscle mass in neonatal mammals, which increases the risk of developing obesity and diabetes in adult life. However, the associated molecular mechanisms remain unclear. Here, we investigated how the nutrient (calorie) availability affects embryonic myogenesis using a porcine model. Sows were given a normal or calorie restricted diet, following which skeletal muscle was harvested from the fetuses at 35, 55, and 90 days of gestation (dg) and used for histochemical analysis and high-throughput sequencing. We observed abrupt repression of primary myofiber formation following maternal calorie restriction (MCR). Transcriptome profiling of prenatal muscles revealed that critical genes and muscle-specific miRNAs associated with increased proliferation and myoblast differentiation were downregulated during MCR-induced repression of myogenesis. Moreover, we identified several novel miRNA-mRNA interactions through an integrative analysis of their expression profiles, devising a putative molecular network involved in the regulation of myogenesis. Interestingly, NC_010454.3_1179 was identified as a novel myogenic miRNA that can base-pair with sequences in the 3'-UTR of myogenic differentiation protein 1 (MyoD1). And we found that this UTR inhibited the expression of a linked reporter gene encoding a key myogenic regulatory factor, resulting in suppression of myogenesis. Our results greatly increase our understanding of the mechanisms underlying the nutrient-modulated myogenesis, and may also serve as a valuable resource for further investigation of fundamental developmental processes or assist in rational target selection ameliorating repressed myogenesis under fetal malnutrition.

Induction of Myogenic Differentiation Improves Chemosensitivity of Chemoresistant Cells in Soft-Tissue Sarcoma Cell Lines

Rhabdomyosarcoma (RMS) and rhabdoid tumors (RT) are rare soft-tissue malignancies with the highest incidence in infants, children, and adolescents. Advanced, recurrent, and/or metastatic RMS and RT exhibit poor response to treatment. One of the main mechanisms behind resistance to treatment is believed to be intratumoral heterogeneity. In this study, we investigated the myogenic determination factor 1 (MYOD1) and Noggin (NOG) markers in an embryonal RMS (ERMS) cell line and an RT cell line and the differential response of the MYOD1 and NOG expressing subpopulations to chemotherapy. Importantly, we found that these markers together identify a subpopulation of cells (MYOD1+ NOG+ cells) with primary resistance to Vincristine and Doxorubicin, two commonly used chemotherapies for ERMS and RT. The chemoresistant MYOD1+ NOG+ cells express markers of undifferentiated cells such as myogenin and ID1. Combination of Vincristine with TPA/GSK126, a drug combination shown to induce differentiation of RMS cell lines, is able to partially overcome MYOD1/NOG cells chemoresistance.

MicroRNA-29 family inhibits rhabdomyosarcoma formation and progression by regulating GEFT function

The microRNA-29 family, which contains mir-29a, mir-29b, and mir-29c, can promote or resist the development of several types of tumors. However, its role in rhabdomyosarcoma (RMS) has not been determined. In this work, we detected the expression of mir-29a/b/c in RMS. Results showed that the tissues and cell lines in RMS were significantly lower than those in muscle and human skeletal muscle cells, and that these cell lines could also inhibit the proliferation, migration, and invasion and induce apoptosis of RMS cells. Dual-luciferase reporter assay and RNA immunoprecipitation verified the direct binding site between mir-29a/b/c and GEFT. Under the combined actions of mir-29a/b/c and GEFT, the former weakened the promoting effect of GEFT on RMS cells. Finally, mir-29a inhibited the tumorigenesis of subcutaneous xenografts in nude mice and inhibited the mRNA and protein expression levels of GEFT in transplanted tumors. These findings proved that mir-29 inhibits the occurrence of RMS and may be a potential molecular target.

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.

MiRNAs as Players in Rhabdomyosarcoma Development

Rhabdomyosarcoma (RMS), the most common soft tissue sarcoma of childhood and adolescence, is a rare but aggressive malignancy that originates from immature mesenchymal cells committed to skeletal muscle differentiation. Although RMS is, generally, responsive to the modern multimodal therapeutic approaches, the prognosis of RMS depends on multiple variables and for some patients the outcome remains dismal. Further comprehension of the molecular and cellular biology of RMS would lead to identification of novel therapeutic targets. MicroRNAs (miRNAs) are small non-coding RNAs proved to function as key regulators of skeletal muscle cell fate determination and to play important roles in RMS pathogenesis. The purpose of this review is to better delineate the role of miRNAs as a biomarkers or functional leaders in RMS development, so to possibly elucidate some of RMS molecular mechanisms and potentially therapeutically target them to improve clinical management of pediatric RMS.

Age-Related Alterations in Immune Contexture Are Associated with Aggressiveness in Rhabdomyosarcoma

Adolescents and young adults (AYA) with rhabdomyosarcoma (RMS) form a subgroup of patients whose optimal clinical management and access to care remain a challenge and whose survival lacks behind that of children diagnosed with histologically similar tumors. Understanding the tumor biology that differentiates children from AYA-RMS could provide critical information and drive new initiatives to improve the final outcome. MicroRNA (miRNA) and gene expression profiling (GEP) was evaluated in a RMS cohort of 49 tumor and 15 non-neoplastic tissues. miRNAs analysis identified miR-223 over-expression and miR-431 down-regulation in AYA, validated by Real-Time PCR and miRNA in situ hybridization (ISH). GEP analysis detected 793 age-correlated genes in tumors, of which 194 were anti-correlated. NOTCH2, FGFR1/2 were significantly down-modulated in AYA-RMS. miR-223 was associated with up-regulation of epithelial mesenchymal translation (EMT) and inflammatory pathways, whereas miR-431 was correlated to myogenic differentiation and muscle metabolism. GEP showed an increase in genes associated with CD4 memory resting cells and a decrease in genes associated with γδ T-cells in AYA-RMS. Immunohistochemistry (IHC) analysis demonstrated an increase of infiltrated CD4, CD8, and neutrophils in AYA-RMS tumors. Our results show that aggressiveness of AYA-RMS could be explained by differences in microenvironmental signal modulation mediated by tumor cells, suggesting a fundamental role of immune contexture in AYA-RMS development.

Knockout of Acinar Enriched microRNAs in Mice Promote Duct Formation But Not Pancreatic Cancer

The pancreatic acinar-enriched miR-216a, miR-216b and miR-217 are encoded within the miR217HG. These miRNAs have been purported to play a tumor suppressive role as their expression is reduced in both human and mouse pancreatic ductal adenocarcinoma (PDAC). To examine this possibility, we generated individual, germline knockout (KO) mice of miR-216a, miR-216b or miR-217. Unlike our previous study showing germline deletion of the miR217HG was embryonic lethal, CRISPR-Cas9 deleted portions of the 5' seed region of the miRNAs produced live births. To investigate possible phenotypes during pancreatic acinar ductal metaplasia (ADM), pancreatic acini from wild type and KO mice were plated on collagen and allowed to transdifferentiate over 4 days. Acini from each of the three miRNA KO mice produced greater numbers of ducts compared to controls. Evaluation of the gene expression during in vitro ADM demonstrated an increase in Krt19 and a reduction in acinar genes (Carboxypeptidase A1, Amylase2a) on day 4 of the transdifferentiation. Recovery was delayed for the miR-216a and miR-216b KOs following caerulein-induced acute pancreatitis. Also predominate in the caerulein treated miR-216a and miR-216b KO mice was the presence of pancreatic duct glands (PDGs). To further establish a phenotype, miRNA KO mice were crossed with EL-KRASG12D (EK) mice and followed up to 13 months of age. While all mice developed severe dysplasia and cystic papillary neoplasms, there existed no apparent phenotypic difference in the miRNA KO/EK mice compared to EK mice. Our data does not support a tumor suppressor role for miR-216a, miR-216b or miR-217 in PDAC and emphasizes the need for phenotypic evaluation of miRNAs in complex in vivo models beyond that performed using cell culture.

A miR-206 regulated gene landscape enhances mammary epithelial differentiation

miR‐206 is known to suppress breast cancer. However, while it is expressed in mammary stem cells, its function in such nontumor cells is not well understood. Here, we explore the role of miR‐206 in undifferentiated, stem‐like mammary cells using the murine mammary differentiation model HC11, genome‐wide gene expression analysis, and functional assays. We describe the miR‐206‐regulated gene landscape and propose a network whereby miR‐206 suppresses tumor development. We functionally demonstrate that miR‐206 in nontumor stem‐like cells induces a G1–S cell cycle arrest, and reduces colony formation and epithelial‐to‐mesenchymal transition markers. Finally, we show that addition of miR‐206 accelerates the mammary differentiation process along with related accumulation of lipids. We conclude that miR‐206 impacts a network of signaling pathways, and acts as a regulator of proliferation, stemness, and mammary cell differentiation in nontumor stem‐like mammary cells. Our study provides a broad insight into the breast cancer suppressive functions of miR‐206.

An Insight into the Roles of MicroRNAs and Exosomes in Sarcoma

Sarcomas are rare solid tumors, but at least one-third of patients with sarcoma die from tumor-related disease. MicroRNA (miRNA) is a noncoding RNA that regulates gene expression in all cells and plays a key role in the progression of cancers. Recently, it was identified that miRNAs are transferred between cells by enclosure in extracellular vesicles, especially exosomes. The exosome is a 100 nm-sized membraned vesicle that is secreted by many kinds of cells and contains miRNA, mRNA, DNA, and proteins. Cancer uses exosomes to influence not only the tumor microenvironment but also the distant organ to create a premetastatic niche. The progression of sarcoma is also regulated by miRNAs and exosomes. These miRNAs and exosomes can be targeted as biomarkers and treatments. In this review, we summarize the studies of miRNA and exosomes in sarcoma.

Inflammation-associated miR-155 activates differentiation of muscular satellite cells

Tissue renewal and muscle regeneration largely rely on the proliferation and differentiation of muscle stem cells called muscular satellite cells (MuSCs). MuSCs are normally quiescent, but they are activated in response to various stimuli, such as inflammation. Activated MuSCs proliferate, migrate, differentiate, and fuse to form multinucleate myofibers. Meanwhile, inappropriate cues for MuSC activation induce premature differentiation and bring about stem cell loss. Recent studies revealed that stem cell regulation is disrupted in various aged tissues. We found that the expression of microRNA (miR)-155, which is an inflammation-associated miR, is upregulated in MuSCs of aged muscles, and this upregulation activates the differentiation process through suppression of C/ebpβ, which is an important molecule for maintaining MuSC self-renewal. We also found that Notch1 considerably repressed miR-155 expression, and loss of Notch1 induced miR-155 overexpression. Our findings suggest that miR-155 can act as an activator of muscular differentiation and might be responsible for accelerating aging-associated premature differentiation of MuSCs.

MiRNA-206 suppresses PGE2-induced colorectal cancer cell proliferation, migration, and invasion by targetting TM4SF1

MiRNA (miR)-206 plays a tumor suppressor role in various cancer types. Here, we investigated whether miR-206 is involved in prostaglandin E2 (PGE2)-induced epithelial–mesenchymal transition (EMT) in colorectal cancer (CRC) cells through the targetting of transmembrane 4 L six family member 1 (TM4SF1).

The effect of PGE2 on growth and apoptosis of CRC cells was evaluated using the MTT assay and flow cytometry analysis, respectively. TM4SF1 and miR-206 expression levels were determined with quantitative polymerase chain reaction (qRT-PCR) in CRC tissues and cell lines. The concentration of PGE2 in the serum of CRC patients and healthy controls was measured with an ELISA kit. A miR-206 or TM4SF1 construct was transfected into cells with PGE2. Transwell migration and invasion assays were used to examine cell migration and invasion properties. Additionally, a luciferase assay was performed to determine whether TM4SF1 was directly targetted by miR-206.

We found that miR-206 was down-regulated and TM4SF1 was up-regulated in human CRC tissues and cell lines. Moreover, miR-206 was negatively correlated with TM4SF1 expression. Bioinformatics analysis and a luciferase reporter assay revealed that miR-206 directly targetted the 3′-untranslated region (UTR) of TM4SF1, and TM4SF1 expression was reduced by miR-206 overexpression at both the mRNA and protein levels. Additionally, PGE2 significantly suppressed the expression of miR-206 and increased the expression of TM4SF1 in CRC cells. PGE2 induction led to enhanced CRC cell proliferation, migration, and invasion. Moreover, the overexpression of miR-206 decreased CRC cell proliferation, migration, and invasion compared with control group in PGE2-induced cells, and these effects could be recovered by the overexpression of TM4SF1. Overexpression of miR-206 also suppressed the expression of β-catenin, VEGF, MMP-9, Snail, and Vimentin and enhanced E-cadherin expression in PGE2-induced cells. These results could be reversed by the overexpression of TM4SF1. At last, up-regulation of miR-206 suppressed expression of p-AKT and p-ERK by targetting TM4SF1 in PGE2-induced cells.

Our results provide further evidence that miR-206 has a protective effect on PGE2-induced colon carcinogenesis.

The oncomir face of microRNA-206: A permanent miR-206 transfection study

MiR-206 is a remarkable miRNA because it functions as a suppressor miRNA in rhabdomyosarcoma while at the same time, as previously showed, it can act as an oncomiRNA in SMARCB1 immunonegative soft tissue sarcomas. The aim of this study was to investigate the effect of miR-206 on its several target genes in various human tumorous and normal cell lines. In the current work, we created miR-206-overexpressing cell lines (HT-1080, Caco2, iASC, and SS-iASC) using permanent transfection. mRNA expression of the target genes of miR-206 (SMARCB1, ACTL6A, CCND1, POLA1, NOTCH3, MET, and G6PD) and SMARCB1 protein expression were examined with quantitative real-time polymerase chain reaction, immunoblotting, immunocytochemistry, and flow cytometry. MiRNA inhibition was used to validate our results. We found a diverse silencing effect of miR-206 on its target genes. While an overall tendency of downregulation was noted, expression profiles of individual cell lines showed large variability. Only CCND1 and MET were consistently downregulated. MiR-206 had an antiproliferative effect on a normal human fibroblast cell line. A strong silencing effect of SMARCB1 in miR-206 transfected SS-iASC was most likely caused by the synergic influence of the SS18-SSX1 fusion protein and miR-206. In the same cell line, a moderate decrease of SMARCB1 protein expression could be observed with immunocytochemistry and flow cytometry. In the most comprehensive analysis of miR-206 effects so far, a modest but significant downregulation of miR-206 targets on the mRNA level was confirmed across all cell lines. However, the variability of the effect shows that the action of this miRNA is largely cell context-dependent. Our results also support the conception that the oncomiR effect of miR-206 on SMARCB1 plays an important but not exclusive role in SMARCB1 immunonegative soft tissue sarcomas so it can be considered important in planning the targeted therapy of these tumors in the future. Impact statement Mir-206 is a very unique microRNA because it can act as a suppressor miRNA or as an oncomiRNA depending on the tumor tissue. In SMARCB1 negative soft tissue sarcomas miR-206 is overexpressed, so thus in epithelioid and synovial sarcomas it functions as an oncomiRNA. MiR-206 has diverse silencing effects on its target genes. We found that the action of miR-206 is largely cell context dependent. The oncomiR role of miR-206 is crucial but not exclusive in SMARCB1 negative soft tissue sarcomas and miR-206 has an antiproliferative effect on a normal human fibroblast cell line. Expressions of miR-206 targets observed in tumors can only be reproduced in the corresponding tumorous cell lines. This is the first study which examined the permanent effect of miR-206 on its target genes in normal, tumor, and genetically engineered cell lines.

Induction of morphological and functional differentiation of human neuroblastoma cells by miR-124

Neuroblastoma is the most common extracranial solid tumour in children, and differentiation is considered its most appropriate therapy. In this work, we studied effects of miR-124 overexpression on differentiation in M17 cell line as a model of neuroblastoma cancer. Influence of miR-124 overexpression on differentiation in M17 cells was studied. M17 cells were infected with lentivirus that contained miR-124 precursor sequence and followed for 2 weeks to differentiate. Ectopic expression of miR-124 in M17 cells changed the shape of spherical undifferentiated cells to cells with extended neurites that formed neuronal networks. Overexpression of MiR-124 respectively increased the expression level of markers of β-Tubulin III, MAP2, SYN, NF-M and Nestin by 16-, 5-, 4-, 2.3- and 2-folds at the messenger RNA level. MiR-124 overexpression also increased the protein levels of β-Tubulin III and MAP2. Moreover, exogenous expression of miR-124 significantly increased the intracellular calcium in differentiated M17 cells. Since miR-124 is naturally expressed in neuronal cells and is downregulated in neuroblastoma cancer cells, differentiation with this type of microRNA can be a novel treatment for neuroblastoma cancer.

Hepatocyte Growth Factor Regulates the miR-206-HDAC4 Cascade to Control Neurogenic Muscle Atrophy following Surgical Denervation in Mice

Hepatocyte growth factor (HGF) has been well characterized for its roles in the migration of muscle progenitors during embryogenesis and the differentiation of muscle stem cells, but its function in adult neurogenic muscle atrophic conditions is poorly understood. Here we investigated whether HGF/c-met signaling has any effects on muscle-atrophic conditions. It was found that HGF expression was upregulated in skeletal muscle tissue following surgical denervation and in hSOD1-G93A transgenic mice showing severe muscle loss. Pharmacological inhibition of the c-met receptor decreased the expression level of pri-miR-206, enhanced that of HDAC4 and atrogenes, and resulted in increased muscle atrophy. In C2C12 cells, HGF inhibited phosphorylation of Smad3 and relieved TGF-β-mediated suppression of miR-206 expression via JNK. When extra HGF was exogenously provided through intramuscular injection of plasmid DNA expressing HGF, the extent of muscle atrophy was reduced, and the levels of all affected biochemical markers were changed accordingly, including those of primary and mature miR-206, HDAC4, and various atrogenes. Taken together, our finding suggested that HGF might play an important role in regard to neurogenic muscle atrophy and that HGF might be used as a platform to develop therapeutic agents for neuromuscular disorders.

Therapeutic inhibition of USP7-PTEN network in chronic lymphocytic leukemia: a strategy to overcome TP53 mutated/deleted clones

Chronic Lymphocytic Leukemia (CLL) is a lymphoproliferative disorder with either indolent or aggressive clinical course. Current treatment regiments have significantly improved the overall outcomes even if higher risk subgroups - those harboring TP53 mutations or deletions of the short arm of chromosome 17 (del17p) - remain highly challenging. In the present work, we identified USP7, a known de-ubiquitinase with multiple roles in cellular homeostasis, as a potential therapeutic target in CLL. We demonstrated that in primary CLL samples and in CLL cell lines USP7 is: i) over-expressed through a mechanism involving miR-338-3p and miR-181b deregulation; ii) functionally activated by Casein Kinase 2 (CK2), an upstream interactor known to be deregulated in CLL; iii) effectively targeted by the USP7 inhibitor P5091. Treatment of primary CLL samples and cell lines with P5091 induces cell growth arrest and apoptosis, through the restoration of PTEN nuclear pool, both in TP53-wild type and -null environment. Importantly, PTEN acts as the main tumor suppressive mediator along the USP7-PTEN axis in a p53 dispensable manner. In conclusion, we propose USP7 as a new druggable target in CLL.

LEF1 reduces tumor progression and induces myodifferentiation in a subset of rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and show characteristics of skeletal muscle differentiation. The two major RMS subtypes in children are alveolar (ARMS) and embryonal RMS (ERMS). We demonstrate that approximately 50% of ARMS and ERMS overexpress the LEF1/TCF transcription factor LEF1 when compared to normal skeletal muscle and that LEF1 can restrain aggressiveness especially of ARMS cells. LEF1 knockdown experiments in cell lines reveal that depending on the cellular context, LEF1 can induce pro-apoptotic signals. LEF1 can also suppress proliferation, migration and invasiveness of RMS cells both in vitro and in vivo. Furthermore, LEF1 can induce myodifferentiation of the tumor cells. This may involve regulation of other LEF1/TCF factors i.e. TCF1, whereas β-catenin activity plays a subordinate role. Together these data suggest that LEF1 rather has tumor suppressive functions and attenuates aggressiveness in a subset of RMS.

Activation of AMPK inhibits TGF-β1-induced airway smooth muscle cells proliferation and its potential mechanisms

The aims of the present study were to examine signaling mechanisms underlying transforming growth factor β1 (TGF-β1)-induced airway smooth muscle cells (ASMCs) proliferation and to determine the effect of adenosine monophosphate-activated protein kinase (AMPK) activation on TGF-β1-induced ASMCs proliferation and its potential mechanisms. TGF-β1 reduced microRNA-206 (miR-206) level by activating Smad2/3, and this in turn up-regulated histone deacetylase 4 (HDAC4) and consequently increased cyclin D1 protein leading to ASMCs proliferation. Prior incubation of ASMCs with metformin induced AMPK activation and blocked TGF-β1-induced cell proliferation. Activation of AMPK slightly attenuated TGF-β1-induced miR-206 suppression, but dramatically suppressed TGF-β1-caused HDAC4 up-expression and significantly increased HDAC4 phosphorylation finally leading to reduction of up-regulated cyclin D1 protein expression. Our study suggests that activation of AMPK modulates miR-206/HDAC4/cyclin D1 signaling pathway, particularly targeting on HDAC4, to suppress ASMCs proliferation and therefore has a potential value in the prevention and treatment of asthma by alleviating airway remodeling.

Regulation of Skeletal Muscle Myoblast Differentiation and Proliferation by Pannexins

Pannexins are newly discovered channels that are now recognized as mediators of adenosine triphosphate release from several cell types allowing communication with the extracellular environment. Pannexins have been associated with various physiological and pathological processes including apoptosis, inflammation, and cancer. However, it is only recently that our work has unveiled a role for Pannexin 1 and Pannexin 3 as novel regulators of skeletal muscle myoblast proliferation and differentiation. Myoblast differentiation is an ordered multistep process that includes withdrawal from the cell cycle and the expression of key myogenic factors leading to myoblast differentiation and fusion into multinucleated myotubes. Eventually, myotubes will give rise to the diverse muscle fiber types that build the complex skeletal muscle architecture essential for body movement, postural behavior, and breathing. Skeletal muscle cell proliferation and differentiation are crucial processes required for proper skeletal muscle development during embryogenesis, as well as for the postnatal skeletal muscle regeneration that is necessary for muscle repair after injury or exercise. However, defects in skeletal muscle cell differentiation and/or deregulation of cell proliferation are involved in various skeletal muscle pathologies. In this review, we will discuss the expression of pannexins and their post-translational modifications in skeletal muscle, their known functions in various steps of myogenesis, including myoblast proliferation and differentiation, as well as their possible roles in skeletal muscle development, regeneration, and diseases such as Duchenne muscular dystrophy.

MiR-34a and miR-206 act as novel prognostic and therapy biomarkers in cervical cancer

Background

Recent evidence indicated that the aberrant expression of microRNA plays a crucial role in the development of cervical cancer. The overall shorter survival was strongly related to the abnormal expression of microRNA-34a (miR-34a) and microRNA-206 (miR-206), which target B cell lymphoma-2(Bcl2) and c-Met. Hepatocyte growth factor (HGF)/c-Met pathway is related to the occurrence, development and prognosis of cervical cancer, and c-Met is significantly overexpressed in cervical squamous cell carcinoma. Bcl2 is also considered to be a promising target for developing novel anticancer treatments.

Methods

In this study, we detect the expression of miR-34a and miR-206 in the cervical cancer tissue through quantificational real-time polymerase chain reaction (qRT-PCR) assay, and the expression of Bcl2 and c-Met from cervical cancer tissue were detected by immunohistochemistry.

Results

The expression of miR-34a and miR-206 were down-regulated in the cervical cancer tissue through qRT-PCR assay. As target genes of miR-34a and miR-206, Bcl2 and c-Met were up-regulated in cervical cancer tissues through qRT-PCR assay and immunohistochemistry. Kaplan–Meier and log-rank analysis revealed that down-regulated expression of miR-34a and miR-206 were strongly related to shorter overall survival. Multivariate Cox proportional hazards model for all variables that were statistically significant in the univariate analysis demonstrated that miR-34a (P = 0.038) and miR-206 (P = 0.008) might be independent prognostic factors for overall survival of patients suffering from cervical cancer.

Conclusions

The up-regulation of Bcl2 and c-Met promotes the cervical cancer’s progress, and the expression of miR-34a and miR-206 significantly correlated with the progression and prognosis in cervical cancer. All of these suggested that miR-34a and miR-206 might be the novel prognostic and therapy tools in cervical cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-017-0431-9) contains supplementary material, which is available to authorized users.

An Examination of the Role of Transcriptional and Posttranscriptional Regulation in Rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is an aggressive family of soft tissue tumors that most commonly manifests in children. RMS variants express several skeletal muscle markers, suggesting myogenic stem or progenitor cell origin of RMS. In this review, the roles of both recently identified and well-established microRNAs in RMS are discussed and summarized in a succinct, tabulated format. Additionally, the subtypes of RMS are reviewed along with the involvement of basic helix-loop-helix (bHLH) proteins, Pax proteins, and microRNAs in normal and pathologic myogenesis. Finally, the current and potential future treatment options for RMS are outlined.

miR-127 enhances myogenic cell differentiation by targeting S1PR3

MicroRNAs (miRNAs) have recently been implicated in muscle stem cell function. miR-127 is known to be predominantly expressed in skeletal muscle, but its roles in myogenic differentiation and muscle regeneration are unknown. Here, we show that miR-127 is upregulated during C2C12 and satellite cell (SC) differentiation and, by establishing C2C12 cells stably expressing miR-127, demonstrate that overexpression of miR-127 in C2C12 cells enhances myogenic cell differentiation. To investigate the function of miR-127 during muscle development and regeneration in vivo, we generated miR-127 transgenic mice. These mice exhibited remarkably accelerated muscle regeneration compared with wild-type mice by promoting SC differentiation. Mechanistically, we demonstrated that the gene encoding sphingosine-1-phosphate receptor 3 (S1PR3), a G-protein-coupled receptor for sphingosine-1-phosphate, is a target of miR-127 required for its function in promoting myogenic cell differentiation. Importantly, overexpression of miR-127 in muscular dystrophy model mdx mice considerably ameliorated the disease phenotype. Thus, our findings suggest that miR-127 may serve as a potential therapeutic target for the treatment of skeletal muscle disease in humans.

MicroRNA and gene co-expression networks characterize biological and clinical behavior of rhabdomyosarcomas

Rhabdomyosarcomas (RMS) in children and adolescents are heterogeneous sarcomas broadly defined by skeletal muscle features and the presence/absence of PAX3/7-FOXO1 fusion genes. MicroRNAs are small non-coding RNAs that regulate gene expression in a cell context specific manner. Sequencing analyses of microRNAs in 64 RMS revealed expression patterns separating skeletal muscle, fusion gene positive and negative RMS. Integration with parallel gene expression data assigned biological functions to 12 co-expression networks/modules that reassuringly included myogenic roles strongly correlated with microRNAs known in myogenesis and RMS development. Modules also correlated with clinical outcome and fusion status. Regulation of microRNAs by the fusion protein was demonstrated after PAX3-FOXO1 reduction, exemplified by miR-9-5p. MiR-9-5p levels correlated with poor outcome, even within fusion gene positive RMS, and were higher in metastatic versus non-metastatic disease. MiR-9-5p reduction inhibited RMS cell migration. Our findings reveal microRNAs in a regulatory framework of biological and clinical significance in RMS.

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RNAseq profiled miRNA expression in 64 rhabdomyosarcomas (RMS).

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MiRNA expression distinguished muscle and RMS on the basis of fusion gene status.

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Co-expression networks linked to function, clinical data and fusion gene status.

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Identified miRNAs, including miR-9-5p, altered by the PAX3-FOXO1 fusion protein.

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Demonstrated clinical and functional role for miR-9-5p in RMS.

From Nutrient to MicroRNA: a Novel Insight into Cell Signaling Involved in Skeletal Muscle Development and Disease

Skeletal muscle is a remarkably complicated organ comprising many different cell types, and it plays an important role in lifelong metabolic health. Nutrients, as an external regulator, potently regulate skeletal muscle development through various internal regulatory factors, such as mammalian target of rapamycin (mTOR) and microRNAs (miRNAs). As a nutrient sensor, mTOR, integrates nutrient availability to regulate myogenesis and directly or indirectly influences microRNA expression. MiRNAs, a class of small non-coding RNAs mediating gene silencing, are implicated in myogenesis and muscle-related diseases. Meanwhile, growing evidence has emerged supporting the notion that the expression of myogenic miRNAs could be regulated by nutrients in an epigenetic mechanism. Therefore, this review presents a novel insight into the cell signaling network underlying nutrient-mTOR-miRNA pathway regulation of skeletal myogenesis and summarizes the epigenetic modifications in myogenic differentiation, which will provide valuable information for potential therapeutic intervention.

Deep Sequencing Reveals a Novel miR-22 Regulatory Network with Therapeutic Potential in Rhabdomyosarcoma

Current therapeutic options for the pediatric cancer rhabdomyosarcoma have not improved significantly, especially for metastatic rhabdomyosarcoma. In the current work, we performed a deep miRNA profiling of the three major human rhabdomyosarcoma subtypes, along with cell lines and normal muscle, to identify novel molecular circuits with therapeutic potential. The signature we determined could discriminate rhabdomyosarcoma from muscle, revealing a subset of muscle-enriched miRNA (myomiR), including miR-22, which was strongly underexpressed in tumors. miR-22 was physiologically induced during normal myogenic differentiation and was transcriptionally regulated by MyoD, confirming its identity as a myomiR. Once introduced into rhabdomyosarcoma cells, miR-22 decreased cell proliferation, anchorage-independent growth, invasiveness, and promoted apoptosis. Moreover, restoring miR-22 expression blocked tumor growth and prevented tumor dissemination in vivo Gene expression profiling analysis of miR-22-expressing cells suggested TACC1 and RAB5B as possible direct miR-22 targets. Accordingly, loss- and gain-of-function experiments defined the biological relevance of these genes in rhabdomyosarcoma pathogenesis. Finally, we demonstrated the ability of miR-22 to intercept and overcome the intrinsic resistance to MEK inhibition based on ERBB3 upregulation. Overall, our results identified a novel miR-22 regulatory network with critical therapeutic implications in rhabdomyosarcoma. Cancer Res; 76(20); 6095-106. ©2016 AACR.

MicroRNA-206 Inhibited the Progression of Glioblastoma Through BCL-2

Gliomas are the most common type of brain tumor and have a poor prognosis. MicroRNAs (miRNAs) are a class of small, endogenous, and non-coding RNAs that play crucial roles in cell proliferation, survival, and invasion. Deregulated expression of miR-206 has been investigated in many cancers. However, the role of miR-206 in glioblastoma is still unclear. In the present study, we found that the expression of miR-206 was decreased in cancer tissues compared with normal tissues. However, the expression level of BCL-2 was higher in cancer tissues than that in normal tissues (all p < 0.001). Statistically, the expression level of BCL-2 was inversely correlated with the miR-206. In addition, the overall survival of glioblastoma patients with lower miR-206 expression was significantly shorter than those with high miR-206 expression (p < 0.001). Besides, the expression of miR-206 was also decreased in U87 and U251 cells. In vitro assays showed that ectopic miR-206 expression affected the proliferation, cell cycle, and invasion in U87 and U251 cells. Importantly, we identified BCL-2 as a direct target of miR-206 in U87 and U251 cells using luciferase assay. Overexpression of BCL-2 partially attenuated the miR-206-mediated cell proliferation. In vivo, overexpression of miR-206 suppressed the progression of glioblastoma cells using mice xenograft model. In conclusion, this study suggested that miR-206 could act as a tumor suppressor gene through inhibiting BCL-2 in the development of glioblastoma.

Constitutive activation of MET signaling impairs myogenic differentiation of rhabdomyosarcoma and promotes its development and progression

Rhabdomyosarcoma (RMS) is a soft tissue sarcoma, which may originate from impaired differentiation of mesenchymal stem cells (MSC). Expression of MET receptor is elevated in alveolar RMS subtype (ARMS) which is associated with worse prognosis, compared to embryonal RMS (ERMS). Forced differentiation of ARMS cells diminishes MET level and, as shown previously, MET silencing induces differentiation of ARMS. In ERMS cells introduction of TPR-MET oncogene leads to an uncontrolled overstimulation of the MET receptor downstream signaling pathways. In vivo, tumors formed by those cells in NOD-SCID mice display inhibited differentiation, enhanced proliferation, diminished apoptosis and increased infiltration of neutrophils. Consequently, tumors grow significantly faster and they display enhanced ability to metastasize to lungs and to vascularize due to elevated VEGF, MMP9 and miR-378 expression. In vitro, TPR-MET ERMS cells display enhanced migration, chemotaxis and invasion toward HGF and SDF-1. Introduction of TPR-MET into MSC increases survival and may induce expression of early myogenic factors depending on the genetic background, and it blocks terminal differentiation of skeletal myoblasts. To conclude, our results suggest that activation of MET signaling may cause defects in myogenic differentiation leading to rhabdomyosarcoma development and progression.

miR-206 Inhibits Stemness and Metastasis of Breast Cancer by Targeting MKL1/IL11 Pathway

Purpose: Effective targeting of cancer stem cells is necessary and important for eradicating cancer and reducing metastasis-related mortality. Understanding of cancer stemness-related signaling pathways at the molecular level will help control cancer and stop metastasis in the clinic.Experimental Design: By analyzing miRNA profiles and functions in cancer development, we aimed to identify regulators of breast tumor stemness and metastasis in human xenograft models in vivo and examined their effects on self-renewal and invasion of breast cancer cells in vitro To discover the direct targets and essential signaling pathways responsible for miRNA functions in breast cancer progression, we performed microarray analysis and target gene prediction in combination with functional studies on candidate genes (overexpression rescues and pheno-copying knockdowns).Results: In this study, we report that hsa-miR-206 suppresses breast tumor stemness and metastasis by inhibiting both self-renewal and invasion. We identified that among the candidate targets, twinfilin (TWF1) rescues the miR-206 phenotype in invasion by enhancing the actin cytoskeleton dynamics and the activity of the mesenchymal lineage transcription factors, megakaryoblastic leukemia (translocation) 1 (MKL1), and serum response factor (SRF). MKL1 and SRF were further demonstrated to promote the expression of IL11, which is essential for miR-206's function in inhibiting both invasion and stemness of breast cancer.Conclusions: The identification of the miR-206/TWF1/MKL1-SRF/IL11 signaling pathway sheds lights on the understanding of breast cancer initiation and progression, unveils new therapeutic targets, and facilitates innovative drug development to control cancer and block metastasis. Clin Cancer Res; 23(4); 1091-103. ©2016 AACR.

MicroRNA-206 inhibits the viability and migration of human lung adenocarcinoma cells partly by targeting MET

MicroRNA (miRNA)-based targeting in cancer has emerged as a potential therapeutic strategy. miR-206 has recently been implicated in cancer. However, the role and molecular mechanism of miR-206 in lung adenocarcinoma are still unclear. The present study revealed that miR-206 was downregulated in human lung adenocarcinoma tissues. Overexpression of miR-206 in human lung adenocarcinoma-derived cells significantly inhibited cell viability and migration. Further experiments indicated that the overexpression of miR-206 decreased the expression of MET at the messenger RNA and protein levels via direct targeting of MET in a 3'-untranslated region-dependent manner. The knockdown of MET by small interfering RNA partly led to a phenocopy effect of miR-206. In conclusion, the present study identified miR-206 as a potential tumor suppressor of lung adenocarcinoma that exerts its functions, in part, by negative regulation of MET.