Regulation of onco and tumor suppressor MiRNAs by mTORC1 inhibitor PRP-1 in human chondrosarcoma

Epigenetic Abnormalities in Chondrosarcoma

In recent years, our understanding of the epigenetic mechanisms involved in tumor pathology has improved greatly. DNA and histone modifications, such as methylation, demethylation, acetylation, and deacetylation, can lead to the up-regulation of oncogenic genes, as well as the suppression of tumor suppressor genes. Gene expression can also be modified on a post-transcriptional level by microRNAs that contribute to carcinogenesis. The role of these modifications has been already described in many tumors, e.g., colorectal, breast, and prostate cancers. These mechanisms have also begun to be investigated in less common tumors, such as sarcomas. Chondrosarcoma (CS) is a rare type of tumor that belongs to sarcomas and is the second most common malignant bone tumor after osteosarcoma. Due to unknown pathogenesis and resistance to chemo- and radiotherapies of these tumors, there is a need to develop new potential therapies against CS. In this review, we summarize current knowledge on the influence of epigenetic alterations in the pathogenesis of CS by discussing potential candidates for future therapies. We also emphasize ongoing clinical trials that use drugs targeting epigenetic modifications in CS treatment.

MicroRNA‑195 suppresses cell proliferation, migration and invasion in epithelial ovarian carcinoma via inhibition of the CDC42/CCND1 pathway

Epithelial ovarian carcinoma (EOC) is the most common cause of gynecological cancer mortality, and poses a threat to women. MicroRNA-195 (miR-195) has been reported to induce apoptosis of human OVCAR-3 cells by inhibiting the VEGFR2/AKT pathway. However, the role of miR-195 in EOC remains unknown. A previous study reported that cell division cycle 42 (CDC42) can serve as a target gene of miR-195 and mediate malignant progression of esophageal squamous cell carcinoma (ESCC). The aim of the present study was to investigate the role of miR-195 in EOC and the regulation in CDC42/CCND1 pathway. Tissues samples and clinical materials were collected from 78 enrolled patients with EOC to analyze the expression and clinical significance of miR-195, CDC42 and cyclin D1 (CCND1). Human EOC cell lines OVCA420, OVCAR-3, A2780 and SKOV3 cell lines were used to assess the expression and function of miR-195, CDC42 and CCND1 in vitro. Cell proliferation, the cell cycle and apoptosis, as well as the cell migratory and invasive abilities were detected in vitro using BrdU incorporation, colony formation, wound healing and Transwell invasion assays, along with flow cytometry. miR-195 was downregulated, while CDC42 and CCND1 were upregulated in human EOC tissues and cells, and the aberrant expression of both was associated with increased EOC malignancy. Moreover, miR-195 expression was negatively correlated with CDC42 and CCND1 expression levels, and negatively regulated these expression levels. Thus, it was suggested that miR-195 functions as a tumor suppressor, but CDC42 and CCND1 act as tumor promoters based their abilities to enhance cell proliferation, cell cycle entry, migration and invasion, as well as decrease apoptosis in OVCAR-3 cells. the present results demonstrated that miR-195 inhibited human EOC progression by downregulating CDC42 and CCND1 expression. Furthermore, it was identified that miR-195, CDC42 and CCND1 may be effective biomarkers for EOC diagnosis and treatment.

Morpho‑functional study of the hypothalamic proline‑rich polypeptide apoptotic activity against mouse Ehrlich ascites carcinoma

A new type of bioactive polypeptides of the neurosecretory hypothalamus called proline‑rich peptides (PRPs), which are isolated from bovine neurosecretory granules of the neurohypophysis, are synthesized in the form of a common precursor protein (neurophysin vasopressin‑associated glycoprotein). Proline‑rich polypetide 1 (PRP‑1; also known as galarmin) is comprised of 15 amino acids residues, and has been suggested to possess anti‑neurodegenerative, immunoregulatory, hematopoietic, antimicrobial and antitumor properties. The cytostatic, antiproliferative effect of PRP‑1 was demonstrated in the human chondrosarcoma JJ012 and triple negative breast carcinoma MDA MB 231 cell lines. PRP‑1 action is disease and tissue specific. To further explore the antitumorigenic and possible cytotoxic effects of PRP‑1, a morpho‑functional study on the effect of PRP‑1 on a mouse Ehrlich ascites carcinoma (EAC) model was conducted. The PRP‑1‑induced morphological features of EAC cells confirmed the apoptotic nature of PRP‑1, as manifested by cell shrinkage, membrane blebbing, chromosome condensation (pyknosis) and nuclear fragmentation (karyorrhexis). The effect of PRP‑1 on the number of tumor cells incubated for 24 h and their viability in trypan blue‑stained samples lead to a 44% reduction in the number of viable cells on day 11 post‑inoculation vs. 22% inhibition of viable cells after PRP‑1 treatment (0.1 µg/ml) on day 7 post‑inoculation. Apoptosis experiments using an Annexin V‑cyanine 3 apoptosis detection kit indicated that 24 h incubation with 0.1 µg/ml PRP‑1 caused a significant increase in the number of apoptotic cells, reaching 50.33%, compared to 8.33% in the sample control on day 7 post‑inoculation.

PRP‑1 significantly decreases the ALDHhigh cancer stem cell population and regulates the aberrant Wnt/β‑catenin pathway in human chondrosarcoma JJ012 cells

Chondrosarcomas are malignant bone tumors refractory to chemotherapy and radiation treatment; thus, novel therapeutic strategies are required. Proline‑rich polypeptide 1 (PRP‑1) has previously demonstrated antitumor properties in chondrosarcoma. To further investigate the role of PRP‑1 in chondrosarcoma cells, its effects on cancer stem cell (CSC) populations were determined by analyzing aldehyde dehydrogenase (ALDH) activity, an established marker of CSCs, in association with regulation of the Wnt/β‑catenin signaling. A significant decrease in ALDHhigh CSCs was observed following treatment of chondrosarcoma JJ012 cells with PRP‑1. For RT2 profiler PCR array analysis of Wnt/β‑catenin signaling genes, cells were sorted into: i) Bulk JJ012 cells; ii) ALDHhigh cells sorted from untreated JJ012 cells (ALDHhigh‑untreated); and iii) ALDHlow cells sorted from PRP‑1‑treated JJ012 cells (ALDHlow‑PRP‑1). The expression levels of Wnt/β‑catenin signaling genes were determined to be downregulated in the ALDHhigh‑untreated cells and upregulated in ALDHlow‑PRP‑1 cells when compared to the bulk JJ012 cells. Additionally, two important oncogenes involved in this pathway, MMP7 and CCND2, were found to be downregulated in the ALDHlow‑PRP‑1 cells. Immunocytochemistry demonstrated the localization of β‑catenin in the nuclei of the PRP‑1‑treated cells. Western blotting indicated increased β‑catenin expression in the ALDHlow‑PRP‑1 cells compared with the bulk JJ012 cells. Analysis of the cytoplasmic and nuclear fractions of cells treated with increasing concentrations of PRP‑1 and β‑catenin nuclear translocation inhibitor CGP57380, suggested the nuclear translocation of β‑catenin following PRP‑1 treatment. In addition, treatment of JJ012 cells with a specific ALDH inhibitor, diethylaminobenzaldehyde, and PRP‑1 resulted in a significant decrease in cytoplasmic β‑catenin protein expression. This indicated that ALDH inactivation may be associated with the nuclear translocation of β‑catenin. Derivation of sarcomas from mesenchymal stem cells via inactivation of the Wnt pathway has been previously documented. The findings of the present study support the notion that Wnt/β‑catenin activation may serve a differential role in sarcomas, limiting tumor progression in association with decreased CSC activity.

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.

MicroRNA‑195 is associated with regulating the pathophysiologic process of human laryngeal squamous cell carcinoma

MicroRNAs (miRNAs) have been reported to be associated with the modulation of tumor development, including alterations associated with the development of human laryngeal squamous cell carcinoma (LSCC). The present study was designed to investigate whether miRNA‑195 was associated with the pathophysiologic process of human LSCC and to identify its potential roles and underlying molecular mechanisms. To determine whether miRNA‑195 serves a role in LSCC, reverse transcription‑quantitative polymerase chain reaction was used to detect miRNA‑195 expression in LSCC tissues. The tumor‑suppressive effect of miRNA‑195 was determined by in vitro assays. Gain‑of‑function studies using miRNA‑195 mimics were performed to investigate cell viability, migration and invasion, and apoptosis in the AMC‑HN‑8 cell line. Western blotting was performed to reveal the molecular mechanisms of miRNA‑195 and its downstream signaling pathways in the LSCC AMC‑HN‑8 cell line. The present study demonstrated that miRNA‑195 is downregulated in primary LSCC tumors. Upregulating miRNA‑195 in vitro suppressed cell viability, migration and invasion in AMC‑HN‑8 cells. Overexpression of miRNA‑195 alone in AMC‑HN‑8 cells was sufficient to induce cell apoptosis, as identified by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Compared with the high expression of miRNA‑195 in AMC‑HN‑8 cells, the expression levels of vascular endothelial growth factor receptor‑II protein and downstream signaling pathway proteins, which were associated with cell viability, migration, invasion and apoptosis, were markedly decreased compared with control or miRNA‑195 negative control treatment group. Together, these data suggest the therapeutic potential of miRNA‑195 in modulating cell growth, migration and apoptosis during the pathophysiological progression of LSCC and that miRNA‑195 may serve as a potential therapeutic target in human LSCC.

Toll like receptors TLR1/2, TLR6 and MUC5B as binding interaction partners with cytostatic proline rich polypeptide 1 in human chondrosarcoma

Metastatic chondrosarcoma is a bone malignancy not responsive to conventional therapies; new approaches and therapies are urgently needed. We have previously reported that mTORC1 inhibitor, antitumorigenic cytostatic proline rich polypeptide 1 (PRP-1), galarmin caused a significant upregulation of tumor suppressors including TET1/2 and SOCS3 (known to be involved in inflammatory processes), downregulation of oncoproteins and embryonic stem cell marker miR-302C and its targets Nanog, c-Myc and Bmi-1 in human chondrosarcoma. To understand better the mechanism of PRP-1 action it was very important to identify the receptor it binds to. Nuclear pathway receptor and GPCR assays indicated that PRP-1 receptors are not G protein coupled, neither do they belong to family of nuclear or orphan receptors. In the present study, we have demonstrated that PRP-1 binding interacting partners belong to innate immunity pattern recognition toll like receptors TLR1/2 and TLR6 and gel forming secreted mucin MUC5B. MUC5B was identified as PRP-1 receptor in human chondrosarcoma JJ012 cell line using Ligand-receptor capture technology. Toll like receptors TLR1/2 and TLR6 were identified as binding interaction partners with PRP-1 by western blot analysis in human chondrosarcoma JJ012 cell line lysates. Immunocytochemistry experiments confirmed the finding and indicated the localization of PRP-1 receptors in the tumor nucleus predominantly. TLR1/2, TLR6 and MUC5B were downregulated in human chondrosarcoma and upregulated in dose-response manner upon PRP-1 treatment. Experimental data indicated that in this cellular context the mentioned receptors had tumor suppressive function.

Epigenetic control of cancer by neuropeptides

Neuropeptides act as neurohormones, neurotransmitters and/or neuromodulators. Neuropeptides maintain physiological homeostasis and are paramount in molecular mechanisms of disease progression and regulation, including in cancer. Neuropeptides, by their definition, originate and are secreted from the neuronal cells, they are able to signal to neighboring cells or are released into the blood flow, if they act as neurohormones. The majority of neuropeptides exert their functions through G protein-coupled receptors, with certain exceptions. Although previous studies indicate that neuropeptides function in supporting proliferation of malignant cells in many types of solid tumor, the antitumorigenic action of the neuropeptides and their receptors, for example, in gastric cancers and chondrosarcoma, were also reported. It is known that epigenetically modified chromatin regulates molecular mechanisms involved in gene expression and malignant progression. The epigenetic modifications are genetically heritable, although they do not cause changes in DNA sequence. DNA methylation, histone modifications and miRNA expression are subject to those modifications. While there is substantial data on epigenetic regulation of neuropeptides, the epigenetic control of cancer by neuropeptides is considered to be uncharted territory. The aim of the current review is to describe the involvement of neuropeptides in the epigenetic machinery of cancer based on data obtained from our laboratory and from other authors.

Effect of cytostatic proline rich polypeptide-1 on tumor suppressors of inflammation pathway signaling in chondrosarcoma

Cytokines produced in the tumour microenvironment exert an important role in cancer pathogenesis and in the inhibition of disease progression. Cancer of the cartilage is termed metastatic chondrosarcoma; however, the signaling events resulting in mesenchymal cell transformation to sarcoma have yet to be fully elucidated. The present study aimed to characterize the cytokine expression profile in the human JJ012 chondrosarcoma cell line, as well as the effect of cytostatic proline-rich polypeptide-1 (PRP-1). Western blot experiments demonstrated that the levels of suppressor of cytokine signaling 3 (SOCS3) were upregulated in chondrocytes compared with chondrosarcoma cells. Addition of PRP-1 restored the expression of the tumor suppressors, SOCS3 and ten-eleven-translocation methylcytosine dioxygenase 1 and 2 (TET1/2), in a dose-responsive manner. It is known that methylation of histone H3K9 was eliminated from the promoters of the inflammation-associated genes. PRP-1 inhibited H3K9 demethylase activity with an IC₅₀ (concentration required to give half-maximal inhibition) value of 3.72 µg/ml in the chondrosarcoma cell line. Data obtained from ELISA experiments indicated that the expression of interleukin-6 (IL-6) in chondrosarcoma cells was 86-fold lower compared with that in C28 chondrocytes. In the present study, a 53-fold downregulation of IL-6 expression in co-culture of chondrosarcoma cells and C28 chondrocytes was identified as well. Downregulation of IL-6 expression has been documented in numerous other tumor types, although the reasons for this have not been fully established. In chondrosarcoma, IL-6 manifests itself as an anti-inflammatory agent and, possibly, as an anti-tumorigenic factor. To explore protein-DNA interactions leading to such differences, a gel-shift chemiluminescent assay was performed. Gel shifts were observed for chondrosarcoma and chondrocytes in the lanes that contained nuclear cell extract and oligo-IL-6 DNA. Notably, the DNA-protein complexes in C28 chondrocytes were markedly larger compared with those in chondrosarcoma cells. The mechanisms that underpin such differences, and characterization of the interacting proteins, remain to be fully elucidated.

Induction of the mesenchymal to epithelial transition by demethylation-activated microRNA-125b is involved in the anti-migration/invasion effects of arsenic trioxide on human chondrosarcoma

Background

In addition to treating acute promyelocytic leukemia, arsenic trioxide (ATO) suppresses other solid tumors, including chondrosarcoma. However, the effects of ATO on metastasis in chondrosarcoma cells, and the underlying molecular mechanisms remain unclear.

Methods

The effects of ATO on the migratory and invasive capacities of chondrosarcoma cells were investigated by Wound healing, Transwell and EMT assays. The expression of miR-125b in human chondrosarcoma tissues and cell lines was detected by real-time PCR analysis. Bisulfite sequencing analysis (BSP) was used to detect the effects of ATO on the expression of miR-125b. The gain-of-function and loss-of-function experiments were performed on chondrosarcoma cell lines to investigate the effects of miR-125b on chondrosarcoma invasion, and to determine whether signal transducer and activator of transcription 3(Stat3) mediates these effects. Dual-luciferase reporter assay was used to identify whether Stat3 is a direct target of miR-125b.

Results

MiR-125b was significantly downregulated in human metastatic chondrosarcoma tissues and cell lines but not in non-metastatic chondrosarcoma tissues. ATO up-regulates the expression of miR-125b by the demethylation of DNA. ATO induces MET and attenuates the invasive capacities of chondrosarcoma cells through miR-125b. Stat3 was verified as a direct target of miR-125b, which is involved in ATO regulating EMT-associated traits.

Conclusions

These findings, for the first time, provides evidence that the miR-125b-mediated inhibition of Stat3 is involved in the ATO-induced attenuation of metastasis in chondrosarcoma cells.

No preclinical rationale for IGF1R directed therapy in chondrosarcoma of bone

Background

Chondrosarcoma is a malignant cartilage forming bone tumour for which no effective systemic treatment is available. Previous studies illustrate the need for a better understanding of the role of the IGF pathway in chondrosarcoma to determine if it can be a target for therapy, which was therefore explored in this study.

Methods

Expression of mediators of IGF1R signalling and phosphorylation status of IRS1 was determined in chondrosarcoma cell lines by qRT-PCR and western blot. The effect of activation and inhibition of IGF1R signalling on downstream targets was assessed by western blot. Ten chondrosarcoma cell lines were treated with OSI-906 (IGF1R and IR dual inhibitor) after which cell proliferation and migration were determined by a viability assay and the xCELLigence system, respectively. In addition, four chondrosarcoma cell lines were treated with a combination of doxorubicin and OSI-906. By immunohistochemistry, IGF1R expression levels were determined in tissue microarrays of 187 cartilage tumours and ten paraffin embedded cell lines.

Results

Mediators of IGF1R signalling are heterogeneously expressed and phosphorylated IRS1 was detected in 67 % of the tested chondrosarcoma cell lines, suggesting that IGF1R signalling is active in a subset of chondrosarcoma cell lines. In the cell lines with phosphorylated IRS1, inhibition of IGF1R signalling decreased phosphorylated Akt levels and increased IGF1R expression, but it did not influence MAPK or S6 activity. In line with these findings, treatment with IGF1R/IR inhibitors did not impact proliferation or migration in any of the chondrosarcoma cell lines, even upon stimulation with IGF1. Although synergistic effects of IGF1R/IR inhibition with doxorubicin are described for other cancers, our results demonstrate that this was not the case for chondrosarcoma. In addition, we found minimal IGF1R expression in primary tumours in contrast to the high expression detected in chondrosarcoma cell lines, even if both were derived from the same tumour, suggesting that in vitro culturing upregulates IGF1R expression.

Conclusions

The results from this study indicate that the IGF pathway is not essential for chondrosarcoma growth, migration or chemoresistance. Furthermore, IGF1R is only minimally expressed in chondrosarcoma primary tumours. Therefore, the IGF pathway is not expected to be an effective therapeutic target for chondrosarcoma of bone.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2522-8) contains supplementary material, which is available to authorized users.

Induction of G₂/M Arrest by Berberine via Activation of PI3K/Akt and p38 in Human Chondrosarcoma Cell Line

Berberine is a clinically important natural isoquinoline alkaloid found in many medicinal herbs. Berberine has been shown to have many pharmacological effects including antimicrobial, antitumor, and anti-inflammatory activities. However, the effects and mechanism of action of berberine have not been studied in chondrosarcoma. Therefore, the effects of berberine on proliferation in a human chondrosarcoma cell line (HTB-94) were investigated. Berberine inhibited cell proliferation in a concentration-dependent manner. We also determined that inhibition of cell proliferation by berberine occurred via G₂/M phase arrest in HTB-94 cells. Berberine induced cell cycle arrest at the G₂/M phase by upregulation of p53 and p21 expression and suppressed cyclin B1, cyclin-dependent kinase 1 (cdc2), cdc25c, and phosphorylated retinoblastoma tumor-suppressor protein (pRb) expression. In addition, berberine stimulated phosphorylation of protein kinase B (Akt) and p38 kinase. Inhibition of phosphatidylinositol 3-kinase (PI3K)/Akt with LY294002 (LY) and p38 kinase with SB203580 (SB), respectively, decreased berberine-induced p53 and p21 expression and restored cell proliferation and expression of cyclin B1, cdc2, cdc25c, and pRb cell cycle progression proteins. These results suggest that berberine-induced inhibition of cell proliferation by cell cycle arrest at the G₂/M phases was regulated through PI3K/Akt and p38 kinase pathways in HTB-94 chondrosarcoma cells.

microRNA and Bone Cancer

MicroRNA molecules have a variety of roles in cellular development and proliferation processes, including normal osteogenesis. These effects are exerted through post-translational inhibition of target genes. Altered miRNA expression has been demonstrated in several cancers, both in the tumor tissue and in the peripheral circulation. This may influence carcinogenesis if the specific miRNA targets are encoded by tumor suppressor genes or oncogenes. To date, most research investigating the role of microRNAs and primary bone tumors has focused on osteosarcoma and Ewing sarcoma. Several microRNAs including the miR-34 family have been implicated in osteosarcoma tumorigenesis via effects on the Notch signaling pathway. Progression, invasion, and metastasis of osteosarcoma tumor cells is also influenced by microRNA expression. In addition, microRNA expression may affect the response to chemotherapy in osteosarcoma and thus hold potential for future use as either a prognostic indicator or a therapeutic target. The EWS-FLI1 fusion protein produced in Ewing sarcoma has been shown to induce changes in miRNA expression. MicroRNA expression profiling may have some potential for prediction of disease progression and survival in Ewing sarcoma. There is limited evidence to support a role for microRNAs in other primary bone tumors, either malignant or benign; however, early work is suggestive of involvement in chondrosarcoma, multiple osteochondromatosis, and giant cell tumors of bone.

MicroRNA‑10b suppresses the migration and invasion of chondrosarcoma cells by targeting brain‑derived neurotrophic factor

MicroRNAs (miRs) can lead to mRNA degradation or inhibit protein translation through directly binding to the 3'‑untranslational region (UTR) of their target mRNAs. Deregulation of miR‑10b has been reported to be associated with chondrosarcoma. However, the role of miR‑10b in chondrosarcoma cell migration and invasion, as well as the underlying mechanisms, has not been investigated. In the present study, it was demonstrated that miR‑10b was notably downregulated in the JJ012 and SW1353 chondrosarcoma cell lines compared with the TC28a2 normal chondrocyte line. Treatment with DNA demethylating agent 5‑aza‑2'‑deoxycytidine and histone deacetylase inhibitor 4‑phenylbutyric acid, or transfection with miR‑10b mimics promoted the expression of miR‑10b, which further suppressed the migratory and invasive capacities of JJ012 chondrosarcoma cells. Moreover, brain‑derived neurotrophic factor (BDNF) was identified as a novel target of miR‑10b, and its protein expression level was negatively regulated by miR‑10b in JJ012 cells. Furthermore, overexpression of BDNF reversed the inhibitory effect of miR‑10b upregulation on the migration and invasion of JJ012 cells. In addition, the data suggest that matrix metalloproteinase 1 (MMP1) may be involved in the miR‑10b/BDNF‑mediated chondrosarcoma cell migration and invasion in JJ012 cells. In conclusion, these findings suggest that miR‑10b/BDNF may serve as a potential therapeutic target for chondrosarcoma.

CCL5 promotes VEGF-dependent angiogenesis by down-regulating miR-200b through PI3K/Akt signaling pathway in human chondrosarcoma cells

Chondrosarcoma is the second most common primary malignant bone cancer, with potential for local invasion and distant metastasis. Chemokine CCL5 (formerly RANTES) of the CC-chemokine family plays a crucial role in metastasis. Angiogenesis is essential for the cancer metastasis. However, correlation of CCL5 with vascular endothelial growth factor (VEGF) expression and angiogenesis in human chondrosarcoma is still unknown. CCL5-mediated VEGF expression was assessed by qPCR, ELISA, and Western blotting. CCL5-induced angiogenesis was examined by migration and tube formation in endothelial progenitor cells in vitro. CCL5 increased VEGF expression and also promoted chondrosarcoma conditional medium-mediated angiogenesis in vitro and in vivo. Stimulation of chondrosarcoma with CCL5 augmented PI3K and Akt phosphorylation, while PI3K and Akt inhibitor or siRNA abolished CCL5-induced VEGF expression and angiogenesis. We also demonstrated CCL5 inhibiting miR-200b expression and miR-200b mimic reversing the CCL5-enhanced VEGF expression and angiogenesis. Moreover, in chondrosarcoma patients showed the positive correlation between CCL5 and VEGF; negative correlation between CCL5 and miR-200b. Taken together, results demonstrate CCL5 promoting VEGF-dependent angiogenesis in human chondrosarcoma cells by down-regulating miR-200b through PI3K/Akt signaling pathway.

Epigenetic regulation of embryonic stem cell marker miR302C in human chondrosarcoma as determinant of antiproliferative activity of proline-rich polypeptide 1

Metastatic chondrosarcoma of mesenchymal origin is the second most common bone malignancy and does not respond either to chemotherapy or radiation; therefore, the search for new therapies is relevant and urgent. We described recently that tumor growth inhibiting cytostatic proline-rich polypeptide 1, (PRP-1) significantly upregulated tumor suppressor miRNAs, downregulated onco-miRNAs in human chondrosarcoma JJ012 cell line, compared to chondrocytes culture. In this study we hypothesized the existence and regulation of a functional marker in cancer stem cells, correlated to peptides antiproliferative activity. Experimental results indicated that among significantly downregulated miRNA after PRP-1treatment was miRNAs 302c^*. This miRNA is a part of the cluster miR302-367, which is stemness regulator in human embryonic stem cells and in certain tumors, but is not expressed in adult hMSCs and normal tissues. PRP-1 had strong inhibitory effect on viability of chondrosarcoma and multilineage induced multipotent adult cells (embryonic primitive cell type). Unlike chondrosarcoma, in glioblastoma, PRP-1 does not have any inhibitory activity on cell proliferation, because in glioblastoma miR-302-367 cluster plays an opposite role, its expression is sufficient to suppress the stemness inducing properties. The observed correlation between the antiproliferative activity of PRP-1 and its action on downregulation of miR302c explains the peptides opposite effects on the upregulation of proliferation of adult mesenchymal stem cells, and the inhibition of the proliferation of human bone giant-cell tumor stromal cells, reported earlier. PRP-1 substantially downregulated the miR302c targets, the stemness markers Nanog, c-Myc and polycomb protein Bmi-1. miR302c expression is induced by JMJD2-mediated H3K9me2 demethylase activity in its promoter region. JMJD2 was reported to be a positive regulator for Nanog. Our experimental results proved that PRP-1 strongly inhibited H3K9 activity comprised of a pool of JMJD1 and JMJD2. We conclude that inhibition of H3K9 activity by PRP-1 leads to downregulation of miR302c and its targets, defining the PRP-1 antiproliferative role.

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.

MicroRNA function and dysregulation in bone tumors: the evidence to date

Micro ribonucleic acids (miRNAs) are small non-coding RNA segments that have a role in the regulation of normal cellular development and proliferation including normal osteogenesis. They exert their effects through inhibition of specific target genes at the post-transcriptional level. Many miRNAs have altered expression levels in cancer (either increased or decreased depending on the specific miRNA). Altered miRNA expression profiles have been identified in several malignancies including primary bone tumors such as osteosarcoma and Ewing’s sarcoma. It is thought that they may function as tumor suppressor genes or oncogenes and hence when dysregulated contribute to the initiation and progression of malignancy. miRNAs are also thought to have a role in the development of bone metastases in other malignancies. In addition, evidence increasingly suggests that miRNAs may play a part in determining the response to chemotherapy in the treatment of osteosarcoma. These molecules are readily detectable in tissues, both fresh and formalin fixed paraffin embedded and, more recently, in blood. Although there are fewer published studies regarding circulating miRNA profiles, they appear to reflect changes in tissue expression. Thus miRNAs may serve as potential indicators of disease presence but more importantly, may have a role in disease characterization or as potential therapeutic targets. This review gives a brief overview of miRNA biochemistry and explores the evidence to date implicating these small molecules in the pathogenesis of bone tumors.