Gene Summary

Gene:RUNX2; runt related transcription factor 2
Aliases: CCD, AML3, CCD1, CLCD, OSF2, CBFA1, OSF-2, PEA2aA, PEBP2aA, CBF-alpha-1
Summary:This gene is a member of the RUNX family of transcription factors and encodes a nuclear protein with an Runt DNA-binding domain. This protein is essential for osteoblastic differentiation and skeletal morphogenesis and acts as a scaffold for nucleic acids and regulatory factors involved in skeletal gene expression. The protein can bind DNA both as a monomer or, with more affinity, as a subunit of a heterodimeric complex. Two regions of potential trinucleotide repeat expansions are present in the N-terminal region of the encoded protein, and these and other mutations in this gene have been associated with the bone development disorder cleidocranial dysplasia (CCD). Transcript variants that encode different protein isoforms result from the use of alternate promoters as well as alternate splicing. [provided by RefSeq, Jul 2016]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:runt-related transcription factor 2
Source:NCBIAccessed: 16 March, 2017


What does this gene/protein do?
Show (37)

Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 16 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Stem Cells
  • Gene Expression Regulation
  • RUNX3
  • Apoptosis
  • Vascular Endothelial Growth Factor Receptor-2
  • Tumor Microenvironment
  • Base Sequence
  • Immunohistochemistry
  • Core Binding Factor Alpha 2 Subunit
  • Cell Differentiation
  • Transcriptional Activation
  • Molecular Sequence Data
  • Core Binding Factor Alpha 1 Subunit
  • Biomarkers, Tumor
  • Core Binding Factor alpha Subunits
  • siRNA
  • Breast Cancer
  • Prostate Cancer
  • Adolescents
  • Neoplastic Cell Transformation
  • DNA-Binding Proteins
  • Western Blotting
  • Cell Proliferation
  • Osteoblasts
  • Proteomics
  • DNA Methylation
  • Ovarian Cancer
  • Cell Movement
  • Down-Regulation
  • Neoplasm Proteins
  • Bone Cancer
  • Gene Expression Profiling
  • Messenger RNA
  • RNA-Binding Proteins
  • Cancer Gene Expression Regulation
  • Osteolysis
  • Gene Knockdown Techniques
  • MicroRNAs
  • Chromosome 6
  • Neoplasm Invasiveness
Tag cloud generated 16 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: RUNX2 (cancer-related)

Wang Y
Identifying key stage-specific genes and transcription factors for gastric cancer based on RNA-sequencing data.
Medicine (Baltimore). 2017; 96(4):e5691 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: To identify gastric cancer (GC)-associated genes and transcription factors (TFs) using RNA-sequencing (RNA-seq) data of Asians.
MATERIALS AND METHODS: The RNA-seq data (GSE36968) were downloaded from Gene Expression Omnibus database, including 6 noncancerous gastric tissue samples, 5 stage I GC samples, 5 stage II GC samples, 8 stage III GC samples, and 6 stage IV GC samples. The gene expression values in each sample were calculated using Cuffdiff. Following, stage-specific genes were identified by 1-way analysis of variance and hierarchical clustering analysis. Upstream TFs were identified using Seqpos. Besides, functional enrichment analysis of stage-specific genes was performed by DAVID. In addition, the underlying protein-protein interactions (PPIs) information among stage IV-specific genes were extracted from STRING database and PPI network was constructed using Cytoscape software.
RESULTS: A total of 3576 stage-specific genes were identified, including 813 specifically up-regulated genes in the normal gastric tissues, 2224 stage I and II-specific genes, and 539 stage IV-specific genes. Also, a total of 9 and 11 up-regulated TFs were identified for the stage I and II-specific genes and stage IV-specific genes, respectively. Functional enrichment showed SPARC, MMP17, and COL6A3 were related to extracellular matrix. Notably, 2 regulatory pathways HOXA4-GLI3-RUNX2-FGF2 and HMGA2-PRKCA were obtained from the PPI network for stage IV-specific genes. In the PPI network, TFs HOXA4 and HMGA2 might function via mediating other genes.
CONCLUSION: These stage-specific genes and TFs might act in the pathogenesis of GC in Asians.

Wang Q, Yu W, Huang T, et al.
RUNX2 promotes hepatocellular carcinoma cell migration and invasion by upregulating MMP9 expression.
Oncol Rep. 2016; 36(5):2777-2784 [PubMed] Related Publications
Runt-related transcription factor 2 (RUNX2) was first identified as a transcription factor to play an important role in different biological processes of osteoblast and chondrocyte, including differentiation and migration. Recently, RUNX2 has been implicated in promigratory/proinvasive behavior in different human malignancies. In the present study, we demonstrated that the RUNX2 mRNA and protein expression were both increased significantly in HCC tissues and cell lines. High RUNX2 expression was correlated obviously with poor clinicopathological characteristics including multiple tumor nodes, high histological grading, venous infiltration and advanced tumor-node-metastasis (TNM) stage. In addition, we demonstrated that RUNX2 was a prognostic indicator for predicting 5-year overall survival and disease-free survival of HCC patients. Our studies showed that RUXN2 overexpression promoted, while RUNX2 knockdown inhibited HCC cell migration and invasion in vitro. Notably, RUNX2 positively regulated matrix metalloproteinase 9 (MMP9) accumulation in HCC cells. Furthermore, we confirmed that RUNX2 was positively correlated with MMP9 expression in HCC tissues by Pearson correlation analysis. Mechanistically, we demonstrated that MMP9 overexpression increased HCC cell migration and invasion, while MMP9 knockdown reduced HCC cell migration and invasion in vitro. Alteration of MMP9 expression partially abrogated the effects of RUNX2 on HCC cell migration and invasion, which suggests that RUNX2 developed its pro-metastatic biological function by upregulating the expression of MMP9 in HCC cells. In conclusion, our results reveal that RUNX2 promotes HCC cell migration and invasion by MMP9-mediated pathway, and potentially serves as a new prognostic biomarker and in therapeutic strategies for HCC.

Chen J, Zhang X, Cai H, et al.
Osteogenic activity and antibacterial effect of zinc oxide/carboxylated graphene oxide nanocomposites: Preparation and in vitro evaluation.
Colloids Surf B Biointerfaces. 2016; 147:397-407 [PubMed] Related Publications
The aim of this study was to prepare nanocomposites of carboxylated graphene oxide (GO-COOH) sheets decorated with zinc oxide (ZnO) nanoparticles (NPs) and investigate their advantages in the field of bone tissue engineering. First, ZnO/GO-COOH nanocomposites were synthesized by facile reactions, including the carboxylation of graphene oxide (GO) and the nucleation of ZnO on GO-COOH sheets. The synthesized ZnO/GO-COOH nanocomposites were then characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectra, and transmission electron microscopy (TEM). The biocompatibility, osteogenic activity and antibacterial effect of ZnO/GO-COOH nanocomposites were further investigated. In the nanocomposites, ZnO nanoparticles with a size of approximately 12nm were uniformly decorated on GO-COOH sheets. Compared with GO-COOH and the control group, ZnO/GO-COOH nanocomposites significantly enhanced ALP activity, osteocalcin production and extracellular matrix mineralization as well as up-regulated osteogenic-related genes (ALP, OCN, and Runx2) in MG63 osteoblast-like cells. Moreover, ZnO/GO-COOH nanocomposites had an antibacterial effect against Streptococcus mutans. These results indicated that ZnO/GO-COOH nanocomposites exhibited both osteogenic activity and antibacterial effect and had great potential for designing new biomaterials in the field of bone tissue engineering.

Xu X, Tang X, Guo W, et al.
TCF-1 participates in the occurrence of dedifferentiated chondrosarcoma.
Tumour Biol. 2016; 37(10):14129-14140 [PubMed] Free Access to Full Article Related Publications
The present study demonstrated that T cell factor 1 (TCF-1) protein, a component of the canonical Wnt/β-catenin signaling pathway, can regulate the expression of runt-related transcription factor 2 (runx2) gene and Sry-related HMG box 9 (sox9) gene, which may participate in the differentiation of chondrosarcoma. Dedifferentiated chondrosarcoma (DDCS) is a special variant of conventional chondrosarcoma (CCS), associated with poor survival and high metastasis rate. However, little is known about the mechanism of its occurrence; thus, no effective treatment is available except surgery. Earlier, high expression of runx2 and low expression of sox9 were found in DDCS compared with CCS. Using Western blot to detect clinical tissue samples (including 8 CCS samples and 8 DDCS samples) and immunohistochemistry to detect 85 different-grade chondrosarcoma specimens, a high expression of TCF-1 in DDCS tissues was found compared with CCS tissues. This difference in expression was related to patients' prognosis. Results of luciferase, chromatin immunoprecipitation, and gel electrophoresis mobility shift assays demonstrated that TCF-1 protein could bind to the promoter of runx2 gene directly and sox9 gene indirectly. Hence, it could regulate expression of runx2 gene positively and sox9 gene negatively. Furthermore, in vitro and in vivo experiments showed that TCF-1 protein was closely related to the phenotype and aggressiveness of chondrosarcoma. In conclusion, this study proved that TCF-1 participates in the dedifferentiation of DDCS, which may be mediated by runx2 gene and sox9 gene. Also, TCF-1 can be of important prognostic value and a promising therapeutic target for DDCS patients.

Li G, Song Y, Zhang Y, et al.
miR-34b Targets HSF1 to Suppress Cell Survival in Acute Myeloid Leukemia.
Oncol Res. 2016; 24(2):109-16 [PubMed] Related Publications
Acute myeloid leukemia (AML) is the most lethal hematological malignancy, and the occurrence of chemoresistance prevents the achievement of complete remission following the standard therapy. MicroRNAs have been extensively investigated as critical regulators of hematopoiesis and leukemogenesis, and they represent a promising strategy for AML therapy. In this study, we identified miR-34b as a novel regulator in myeloid proliferation and apoptosis of leukemic cells. We found that miR-34b was developmentally upregulated in plasma and myeloid cells of healthy subjects, while it was significantly reduced in blood samples of patients with AML and AML cell lines. Moreover, the miR-34b mimicked transfection-mediated restoration of miR-34b inhibited cell viability and promoted cell apoptosis of HL-60 and OCI-AML3 cell lines. Using a miRNA predicting algorithm miRanda, we selected a potent target heat shock transcription factor 1 (HSF1) since that is a master regulator of the heat shock response and is associated with cancer aggressiveness and dissemination. In contrast to the level of miR-34b, HSF1 was highly expressed in blood samples of patients with AML and AML cell lines. The luciferase reporter assay revealed that miR-34b directly targeted the HSF1 gene. HSF1 silencing exhibited comparable inhibitory effects on AML cell proliferation and survival. The upregulated HSF1 elevated the activation of the Wnt-β-catenin pathway. In conclusion, miR-34b suppressed AML cell proliferation and survival by targeting HSF1, in turn leading to the inactivation of Wnt-β-catenin pathway, which may highlight a new therapeutic approach for AML.

Li1 XH, Yang CZ, Wang J
Network spatio-temporal analysis predicts disease stage-related genes and pathways in renal cell carcinoma.
Genet Mol Res. 2016; 15(2) [PubMed] Related Publications
The purpose of this study was to screen the key genes and pathways of renal cell carcinoma (RCC) and lay the foundation for its diagnosis and therapy. Microarray data of normal subjects and RCC patients at different stages of disease were used to screen differentially expressed genes (DEGs). Based on the DEGs in the four disease stages, four co-expression networks were constructed using the Empirical Bayes method and hub genes were obtained by centrality analysis. The enriched pathways of the DEGs and the mutual hub genes in the cluster of each disease stage were investigated. The mutual hub genes of the four disease stages in RCC tissue were validated using reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis. A total of 432 DEGs were screened, including 233 upregulated and 199 downregulated genes, by statistical analysis. Centrality analysis of co-expression networks in different disease stages suggested that PLXDC1, IKZF1, RUNX2, and RNF125 were mutual hub genes. Pathway analysis showed that the DEGs were significantly enriched in seven terms. The hub modules in stage I disease were significantly enriched in the complement coagulation cascade pathway and the hub modules of the other three disease stages were enriched in natural killer cell-mediated cytotoxicity. The expression levels of PLXDC1, IKZF1, RUNX2, and RNF125 were significantly different between normal subjects and RCC patients by RT-PCR and western blot. Our study revealed four hub genes (PLXDC1, IKZF1, RUNX2, and RNF125) and two biological pathways that might be underlying biomarkers involved in RCC.

Lu JW, Wang AN, Liao HA, et al.
Cabozantinib is selectively cytotoxic in acute myeloid leukemia cells with FLT3-internal tandem duplication (FLT3-ITD).
Cancer Lett. 2016; 376(2):218-25 [PubMed] Related Publications
Cabozantinib is an oral multikinase inhibitor that exhibits anti-tumor activity in several cancers. We found that cabozantinib was significantly cytotoxic to MV4-11 and Molm-13 cells that harbored FLT3-ITD, resulting in IC50 values of 2.4 nM and 2.0 nM, respectively. However, K562, OCI-AML3 and THP-1 (leukemia cell lines lacking FLT3-ITD) were resistant to cabozantinib, showing IC50 values in the micromolar range. Cabozantinib arrested MV4-11 cell growth at the G0/G1 phase within 24 h, which was associated with decreased phosphorylation of FLT3, STAT5, AKT and ERK. Additionally, cabozantinib induced MV4-11 cell apoptosis in a dose-dependent manner (as indicated by annexin V staining and high levels of cleaved caspase 3 and PARP-1), down-regulated the anti-apoptotic protein survivin and up-regulated the pro-apoptotic protein Bak. Thus, cabozantinib is selectively cytotoxic to leukemia cells with FLT3-ITD, causing cell-cycle arrest and apoptosis. In mouse xenograft model, cabozantinib significantly inhibited MV4-11 and Molm-13 tumor growth at a dosage of 10 mg/kg and showed longer survival rate. Clinical trials evaluating the efficacy of cabozantinib in acute myeloid leukemia (AML) with FLT3-ITD are warranted.

Behray M, Webster CA, Pereira S, et al.
Synthesis of Diagnostic Silicon Nanoparticles for Targeted Delivery of Thiourea to Epidermal Growth Factor Receptor-Expressing Cancer Cells.
ACS Appl Mater Interfaces. 2016; 8(14):8908-17 [PubMed] Related Publications
The novel thiourea-functionalized silicon nanoparticles (SiNPs) have been successfully synthesized using allylamine and sulforaphane, an important anticancer drug, followed by a hydrosilylation reaction on the surface of hydrogen terminated SiNPs. Their physiochemical properties have been investigated by photoluminescence emission, Fourier transform infrared spectroscopy (FTIR) and elemental analysis. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay has been employed to evaluate in vitro toxicity in human colorectal adenocarcinoma (Caco-2) cells and human normal colon epithelial (CCD) cells. The results show significant toxicity of thiourea SiNPs after 72 h of incubation in the cancer cell line, and the toxicity is concentration dependent and saturated for concentrations above 100 μg/mL. Confocal microscopy images have demonstrated the internalization of thiourea-functionalized SiNPs inside the cells. Flow cytometry data has confirmed receptor-mediated targeting in cancer cells. This nanocomposite takes advantage of the epidermal growth factor receptor (EGFR) active targeting of the ligand in addition to the photoluminescence properties of SiNPs for bioimaging purposes. The results suggest that this novel nanosystem can be extrapolated for active targeting of the receptors that are overexpressed in cancer cells such as EGFR using the targeting characteristics of thiourea-functionalized SiNPs and therefore encourage further investigation and development of anticancer agents specifically exploiting the EGFR inhibitory activity of such nanoparticles.

Shin MH, He Y, Marrogi E, et al.
A RUNX2-Mediated Epigenetic Regulation of the Survival of p53 Defective Cancer Cells.
PLoS Genet. 2016; 12(2):e1005884 [PubMed] Free Access to Full Article Related Publications
The inactivation of p53 creates a major challenge for inducing apoptosis in cancer cells. An attractive strategy is to identify and subsequently target the survival signals in p53 defective cancer cells. Here we uncover a RUNX2-mediated survival signal in p53 defective cancer cells. The inhibition of this signal induces apoptosis in cancer cells but not non-transformed cells. Using the CRISPR technology, we demonstrate that p53 loss enhances the apoptosis caused by RUNX2 knockdown. Mechanistically, RUNX2 provides the survival signal partially through inducing MYC transcription. Cancer cells have high levels of activating histone marks on the MYC locus and concomitant high MYC expression. RUNX2 knockdown decreases the levels of these histone modifications and the recruitment of the Menin/MLL1 (mixed lineage leukemia 1) complex to the MYC locus. Two inhibitors of the Menin/MLL1 complex induce apoptosis in p53 defective cancer cells. Together, we identify a RUNX2-mediated epigenetic mechanism of the survival of p53 defective cancer cells and provide a proof-of-principle that the inhibition of this epigenetic axis is a promising strategy to kill p53 defective cancer cells.

Liao Y, Lv G, Wang B, et al.
Imatinib promotes apoptosis of giant cell tumor cells by targeting microRNA-30a-mediated runt-related transcription factor 2.
Mol Med Rep. 2016; 13(2):1739-45 [PubMed] Related Publications
Giant cell tumor (GCT) is an aggressive type of bone tumor consisting of multinucleated osteoclast-like giant cells. Imatinib is a selective inhibitor for certain type III tyrosine kinase receptor family members with a variety of beneficial effects. The purpose of the present study was to determine the therapeutic potential and underlying mechanism of imatinib against GCT. In the present study, cell viability and apoptosis in GCT were analyzed using the MTT assay, flow cytometry and DAPI staining assay. Caspase-3 and -9 activity in GCT cells were analyzed with colorimetric assay kits. In addition, the expression levels of runt-related transcription factor 2 (RunX2) protein and microRNA-30a (miR-30a) in GCT cells were detected using western blotting and quantitative polymerase chain reaction, respectively. Results from the present study demonstrated that imatinib treatment inhibited cell viability, increased cell apoptosis, and significantly promoted caspase-3 and -9 activity in GCT. In addition, imatinib treatment decreased the RunX2 protein expression level. Notably, imatinib was demonstrated to increase miR-30a expression. However, upregulation of miR-30a expression reduced the RunX2 protein expression level, and downregulation of miR-30a expression reversed the anticancer effect of imatinib on GCT, increasing the expression level of RunX2 protein in GCT. The results of the present study indicate that imatinib promotes apoptosis of GCT cells by targeting the miR-30a-mediated RunX2 signaling pathway.

Sengupta D, Byrum SD, Avaritt NL, et al.
Quantitative Histone Mass Spectrometry Identifies Elevated Histone H3 Lysine 27 (Lys27) Trimethylation in Melanoma.
Mol Cell Proteomics. 2016; 15(3):765-75 [PubMed] Free Access to Full Article Related Publications
Normal cell growth is characterized by a regulated epigenetic program that drives cellular activities such as gene transcription, DNA replication, and DNA damage repair. Perturbation of this epigenetic program can lead to events such as mis-regulation of gene transcription and diseases such as cancer. To begin to understand the epigenetic program correlated to the development of melanoma, we performed a novel quantitative mass spectrometric analysis of histone post-translational modifications mis-regulated in melanoma cell culture as well as patient tumors. Aggressive melanoma cell lines as well as metastatic melanoma were found to have elevated histone H3 Lys(27) trimethylation (H3K27me3) accompanied by overexpressed methyltransferase EZH2 that adds the specific modification. The altered epigenetic program that led to elevated H3K27me3 in melanoma cell culture was found to directly silence transcription of the tumor suppressor genes RUNX3 and E-cadherin. The EZH2-mediated silencing of RUNX3 and E-cadherin transcription was also validated in advanced stage human melanoma tissues. This is the first study focusing on the detailed epigenetic mechanisms leading to EZH2-mediated silencing of RUNX3 and E-cadherin tumor suppressors in melanoma. This study underscores the utility of using high resolution mass spectrometry to identify mis-regulated epigenetic programs in diseases such as cancer, which could ultimately lead to the identification of biological markers for diagnostic and prognostic applications.

Al-Henhena N, Khalifa SA, Ying RP, et al.
Evaluation of chemopreventive potential of Strobilanthes crispus against colon cancer formation in vitro and in vivo.
BMC Complement Altern Med. 2015; 15(1):419 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: With cancer being one of the major causes of death around the world, studies are ongoing to find new chemotherapeutic leads. There are common mechanisms for colorectal cancer (CRC) formation. Several are connected with oxidative stress-induced cell apoptosis and others are related to imbalanced homeostasis or intake of drugs/toxins. Plants that have been used for decades in folk and traditional medicine have been accepted as one of the commonest sources of discovered natural agents of cancer chemotherapy and chemoprevention. The aim was to study the antioxidant and chemopreventive effects of Strobilanthes crispus on colorectal cancer formation.
METHODS: Five groups of rats were injected subcutaneously with AOM, 15 mg/kg body weight, each once weekly for 2 weeks. The cancer group was continued on 10 % Tween-20 feeding for 8 weeks. The standard drug group was continued on 35 mg/kg 5-fluorouracil intraperitoneal injection twice a week for 8 weeks, and the experimental groups were continued on 250 and 500 mg/kg S. crispus extract oral feeding for 8 weeks, respectively. The normal group was injected subcutaneously with normal saline once a week for 2 weeks, followed by oral administration of 10 % Tween-20 for 8 weeks. All the rats were sacrificed after 10 weeks. The colons were evaluated grossly and histopathologically for aberrant crypt foci (ACF). Gene expression was performed for Bax, Bcl2, Defa24, Slc24a3, and APC genes by real-time PCR. S. crispus and its fractions were evaluated for their chemopreventive effects against human colorectal adenocarcinoma cell line HT29 and cytotoxicity for normal human colon epithelial cell line CCD 841, and the active fraction was assessed for its components.
RESULTS: We observed significant decrease in total colonic ACF formation, malonaldehyde (MDA) and lactate dehydrogenase (LDH), increase in superoxide dismutase (SOD), up-regulation of APC, Bax and Slc24a3, and down-regulation of Defa24 and Bcl-2 in rats treated with Strobilanthes crispus.
CONCLUSION: Our results support the in vivo protection of S. crispus against CRC formation (azoxymethane-induced aberrant crypt foci) and suggest that the mechanism is highly specific to protect from oxidative insults and the following apoptotic cascade.

Jiang D, Zheng X, Shan W, Shan Y
The overexpression of miR-30a affects cell proliferation of chondrosarcoma via targeting Runx2.
Tumour Biol. 2016; 37(5):5933-40 [PubMed] Related Publications
MicroRNAs (miRNAs) are emerging as important epigenetic modulators of multiple target genes, leading to abnormal cellular signaling involving cellular proliferation in cancers. Aberrant miRNA expression has been observed in human chondrosarcoma (CS). The purpose of the present study was to evaluate the expression and molecular mechanisms of Runx2 and miR-30a in human CS tissues and CS cell lines JJ012, SW1353, and L3252. In the present study, we found that the expression of miR-30a was markedly downregulated in CS cell lines and human CS tissues, compared to matched non-tumor-associated tissues. Furthermore, miR-30a expression was inversely proportional to that of Runx2 messenger RNA (mRNA) and protein. Upregulation of miR-30a dramatically reduced the proliferation, colony formation, and cell cycle-related proteins of CS cells. Flow cytometry analysis showed that ectopic expression of miR-30a significantly decreased the percentage of S phase cells and increased the percentage of G1/G0 phase cells. Luciferase reporter assays confirmed that miR-30a binding to the 3'-untranslated region (3'-UTR) region of Runx2 inhibited the expression of Runx2 in cancer cells. Taken together, our results suggest that miR-30a plays an important role to inhibit the proliferation of CS cells and presents a novel mechanism for direct miRNA-mediated suppression of Runx2 in CS. Thus, miR-30a/Runx2 may have an important role in treatment of CS patients.

Zong JC, Wang X, Zhou X, et al.
Gut-derived serotonin induced by depression promotes breast cancer bone metastasis through the RUNX2/PTHrP/RANKL pathway in mice.
Oncol Rep. 2016; 35(2):739-48 [PubMed] Related Publications
Breast cancer metastasizes to the bone in a majority of patients with advanced disease resulting in bone destruction. The underlying mechanisms are complex, and both processes are controlled by an interaction between locally and systemically derived signals. Clinically, breast cancer patients with depression have a higher risk of bone metastasis, yet the etiology and mechanisms are yet to be elucidated. MDA‑MB‑231 breast cancer cells were used to establish a bone metastasis model by using intracardiac injection in nude mice. Chronic mild stress (CMS) was chosen as a model of depression in mice before and after inoculation of the cells. Knockdown of the RUNX‑2 gene was performed by transfection of the cells with shRNA silencing vectors against human RUNX‑2. A co‑culture system was used to test the effect of the MDA‑MB‑231 cells on osteoclasts and osteoblasts. RT‑PCR and western blotting were used to test gene and protein expression, respectively. We confirmed that depression induced bone metastasis by promoting osteoclast activity while inhibiting osteoblast differentiation. Free serotonin led to an increase in the expression of RUNX2 in breast cancer cells (MDA‑MB‑231), which directly inhibited osteoblast differentiation and stimulated osteoclast differentiation by the PTHrP/RANKL pathway, which caused bone destruction and formed osteolytic bone lesions. Additionally, the interaction between depression and breast cancer cells was interrupted by LP533401 or RUNX2 knockdown. In conclusion, depression promotes breast cancer bone metastasis partly through increasing levels of gut‑derived serotonin. Activation of RUNX2 in breast cancer cells by circulating serotonin appears to dissociate coupling between osteoblasts and osteoclasts, suggesting that the suppression of gut‑derived serotonin decreases the rate of breast cancer bone metastasis induced by depression.

Fu J, Ke X, Tan S, et al.
The natural compound codonolactone attenuates TGF-β1-mediated epithelial-to-mesenchymal transition and motility of breast cancer cells.
Oncol Rep. 2016; 35(1):117-26 [PubMed] Related Publications
Codonolactone (CLT), a natural product, is the major bioactive component of Atractylodes lancea, and also found in a range of other medical herbs, such as Codonopsis pilosula, Chloranthus henryi Hemsl and Atractylodes macrocephala Koidz. This sesquiterpene lactone has been demonstrated to exhibit a range of activities, including anti-allergic activity, anti-inflammatory, anticancer, gastroprotective and neuroprotective activity. Previously, we found that CLT showed significant anti-metastatic properties in vitro and in vivo. In order to determine whether EMT-involved mechanisms contribute to the anti-metastatic effects of CLT, we checked the anti-EMT properties of CLT and its potential mechanisms. Here it was demonstrated that CLT inhibited TGF-β1-induced epithelial-mesenchymal transition (EMT) in vitro and in vivo. Furthermore, downregulation of TGF-β signaling was associated with the anti-EMT properties of CLT. Data from western blotting showed that, in breast cancer cells, TGF-β1 stimulated the activation of Runx2, and CLT blocked the activation of Runx2. Finally, to verify whether CLT-induced EMT inhibition leads to suppression of metastatic potential, the effects of CLT on cell invasion and migration were determined. It was found that TGF-β1-induced migration and invasion was significantly blocked by CLT in both MDA-MB-231 and MDA-MB-468 cells. Collectively, our findings demonstrated that CLT inhibited programming of EMT in vitro and in vivo, resulting in inhibition of motility of metastatic breast cancer cells. The inhibitory effect of CLT was due to its ability to inhibit TGF-β signaling and Runx2 phosphorylation.

Roos A, Satterfield L, Zhao S, et al.
Loss of Runx2 sensitises osteosarcoma to chemotherapy-induced apoptosis.
Br J Cancer. 2015; 113(9):1289-97 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Osteosarcoma (OS) is the most common bone malignancy in the paediatric population, principally affecting adolescents and young adults. Minimal advancements in patient prognosis have been made over the past two decades because of the poor understanding of disease biology. Runx2, a critical transcription factor in bone development, is frequently amplified and overexpressed in OS. However, the molecular and biological consequences of Runx2 overexpression remain unclear.
METHODS: si/shRNA and overexpression technology to alter Runx2 levels in OS cells. In vitro assessment of doxorubicin (doxo)-induced apoptosis and in vivo chemosensitivity studies. Small-molecule inhibitor of c-Myc transcriptional activity was used to assess its role.
RESULTS: Loss of Runx2 sensitises cells to doxo-induced apoptosis both in vitro and in vivo. Furthermore, in conjunction with chemotherapy, decreasing Runx2 protein levels activates both the intrinsic and extrinsic apoptotic pathways. Transplanted tumour studies demonstrated that loss of endogenous Runx2 protein expression enhances caspase-3 cleavage and tumour necrosis in response to chemotherapy. Finally, upon doxo-treated Runx2 knockdown OS cells there was evidence of enhanced c-Myc expression and transcriptional activity. Inhibition of c-Myc under these conditions resulted in decreased activation of apoptosis, therefore insinuating a role for c-Myc in dox-induced activation of apoptotic pathways.
CONCLUSIONS: Therefore, we have established a novel molecular mechanism by which Runx2 provides a chemoprotective role in OS, indicating that in conjunction to standard chemotherapy, targeting Runx2 may be a new therapeutic strategy for patients with OS.

Wobus M, Bornhäuser M, Jacobi A, et al.
Association of the EGF-TM7 receptor CD97 expression with FLT3-ITD in acute myeloid leukemia.
Oncotarget. 2015; 6(36):38804-15 [PubMed] Free Access to Full Article Related Publications
Internal tandem duplications within the juxtamembrane region of the FMS-like tyrosine kinase receptor FLT3 (FLT3-ITD) represents one of the most common mutations in patients with acute myeloid leukemia (AML) which results in constitutive aberrant activation, increased proliferation of leukemic progenitors and is associated with an aggressive clinical phenotype. The expression of CD97, an EGF-TM7 receptor, has been linked to invasive behavior in thyroid and colorectal cancer. Here, we have investigated the association of CD97 with FLT3-ITD and its functional consequences in AML.Higher CD97 expression levels have been detected in 208 out of 385 primary AML samples. This was accompanied by a significantly increased bone marrow blast count as well as by mutations in the FLT3 gene. FLT3-ITD expressing cell lines as MV4-11 and MOLM-13 revealed significantly higher CD97 levels than FLT3 wildtype EOL-1, OCI-AML3 and HL-60 cells which were clearly decreased by the tyrosine kinase inhibitors PKC412 and SU5614. CD97 knock down by short hairpin RNA in MV4-11 cells resulted in inhibited trans-well migration towards fetal calf serum (FCS) and lysophosphatidic acid (LPA) being at least in part Rho-A dependent. Moreover, knock down of CD97 led to an altered mechanical phenotype, reduced adhesion to a stromal layer and lower wildtype FLT3 expression.Our results, thus, constitute the first evidence for the functional relevance of CD97 expression in FLT3-ITD AML cells rendering it a potential new theragnostic target.

Zhang R, Yan S, Wang J, et al.
MiR-30a regulates the proliferation, migration, and invasion of human osteosarcoma by targeting Runx2.
Tumour Biol. 2016; 37(3):3479-88 [PubMed] Related Publications
Osteosarcoma (OS) is the most common primary malignant bone tumor in young patients. However, treatment paradigms and survival rates have not improved in decades. MicroRNAs have been shown to be critical regulators of physiological homeostasis and pathological process, including bone disease. Nearly half of the microRNA (miRNA) genes are located at genomic regions and fragile sites known to be frequently deleted or amplified in various kinds of cancers. In this study, we investigated the role miR-30a in OS. A negative correlation between miR-30a expression and malignant grade was observed in OS cell lines. The overexpression of miR-30a reduced proliferation, migration, and invasion in 143B cells and the inhibitor of miR-30a increased proliferation, migration, and invasion in Saos2 cells. Further studies revealed that runt-related transcription factors 2 (Runx2) was a regulative target gene of miR-30a. Rescue assay significantly reversed the effects of overexpressing or inhibiting miR-30a. miR-30a also suppressed tumor formation and pulmonary metastasis in vivo. All the results suggest a critical role of miR-30a in suppressing proliferation, migration, and invasion of OS by targeting Runx2.

Wysokinski D, Blasiak J, Pawlowska E
Role of RUNX2 in Breast Carcinogenesis.
Int J Mol Sci. 2015; 16(9):20969-93 [PubMed] Free Access to Full Article Related Publications
RUNX2 is a transcription factor playing the major role in osteogenesis, but it can be involved in DNA damage response, which is crucial for cancer transformation. RUNX2 can interact with cell cycle regulators: cyclin-dependent kinases, pRB and p21Cip1 proteins, as well as the master regulator of the cell cycle, the p53 tumor suppressor. RUNX2 is involved in many signaling pathways, including those important for estrogen signaling, which, in turn, are significant for breast carcinogenesis. RUNX2 can promote breast cancer development through Wnt and Tgfβ signaling pathways, especially in estrogen receptor (ER)-negative cases. ERα interacts directly with RUNX2 and regulates its activity. Moreover, the ERa gene has a RUNX2 binding site within its promoter. RUNX2 stimulates the expression of aromatase, an estrogen producing enzyme, increasing the level of estrogens, which in turn stimulate cell proliferation and replication errors, which can be turned into carcinogenic mutations. Exploring the role of RUNX2 in the pathogenesis of breast cancer can lead to revealing new therapeutic targets.

Ferrer-Mayorga G, Alvarez-Díaz S, Valle N, et al.
Cystatin D locates in the nucleus at sites of active transcription and modulates gene and protein expression.
J Biol Chem. 2015; 290(44):26533-48 [PubMed] Free Access to Full Article Related Publications
Cystatin D is an inhibitor of lysosomal and secreted cysteine proteases. Strikingly, cystatin D has been found to inhibit proliferation, migration, and invasion of colon carcinoma cells indicating tumor suppressor activity that is unrelated to protease inhibition. Here, we demonstrate that a proportion of cystatin D locates within the cell nucleus at specific transcriptionally active chromatin sites. Consistently, transcriptomic analysis show that cystatin D alters gene expression, including that of genes encoding transcription factors such as RUNX1, RUNX2, and MEF2C in HCT116 cells. In concordance with transcriptomic data, quantitative proteomic analysis identified 292 proteins differentially expressed in cystatin D-expressing cells involved in cell adhesion, cytoskeleton, and RNA synthesis and processing. Furthermore, using cytokine arrays we found that cystatin D reduces the secretion of several protumor cytokines such as fibroblast growth factor-4, CX3CL1/fractalkine, neurotrophin 4 oncostatin-M, pulmonary and activation-regulated chemokine/CCL18, and transforming growth factor B3. These results support an unanticipated role of cystatin D in the cell nucleus, controlling the transcription of specific genes involved in crucial cellular functions, which may mediate its protective action in colon cancer.

Daiwile AP, Sivanesan S, Izzotti A, et al.
Noncoding RNAs: Possible Players in the Development of Fluorosis.
Biomed Res Int. 2015; 2015:274852 [PubMed] Free Access to Full Article Related Publications
Fluorosis is caused by excess of fluoride intake over a long period of time. Aberrant change in the Runt-related transcription factor 2 (RUNX2) mediated signaling cascade is one of the decisive steps during the pathogenesis of fluorosis. Up to date, role of fluoride on the epigenetic alterations is not studied. In the present study, global expression profiling of short noncoding RNAs, in particular miRNAs and snoRNAs, was carried out in sodium fluoride (NaF) treated human osteosarcoma (HOS) cells to understand their possible role in the development of fluorosis. qPCR and in silico hybridization revealed that miR-124 and miR-155 can be directly involved in the transcriptional regulation of Runt-related transcription factor 2 (RUNX2) and receptor activator of nuclear factor κ-B ligand (RANKL) genes. Compared to control, C/D box analysis revealed marked elevation in the number of UG dinucleotides and D-box sequences in NaF exposed HOS cells. Herein, we report miR-124 and miR-155 as the new possible players involved in the development of fluorosis. We show that the alterations in UG dinucleotides and D-box sequences of snoRNAs could be due to NaF exposure.

Brusgard JL, Choe M, Chumsri S, et al.
RUNX2 and TAZ-dependent signaling pathways regulate soluble E-Cadherin levels and tumorsphere formation in breast cancer cells.
Oncotarget. 2015; 6(29):28132-50 [PubMed] Free Access to Full Article Related Publications
Intratumoral heterogeneity and treatment resistance drive breast cancer (BC) metastasis and recurrence. The RUNX2 transcription factor is upregulated in early stage luminal BC. However, the precise mechanism by which RUNX2 regulates an oncogenic phenotype in luminal BCs remains an enigma. We show that RUNX2 is predictive of poor overall survival in BC patients. RUNX2 associated with the TAZ transcriptional co-activator to promote a tumorigenic phenotype that was inhibited by knockdown of TAZ. RUNX2 increased endogenous TAZ translocation to the nucleus, which was prevented by inhibiting RUNX2. RUNX2/TAZ interaction was associated with ectodomain shedding of an oncogenic soluble E-Cadherin fragment (sE-Cad), which is known to cooperate with human epidermal growth factor receptor-2 (HER2/ErbB2) to increase BC growth. Neutralizing E-Cadherin antibodies or TAZ knockdown reduced the levels of sE-Cad in RUNX2-expressing BC cells and inhibited tumorsphere formation. RUNX2 expression also increased HER2-mediated tumorsphere size, which was reduced after treatment with the HER2-targeting agents Herceptin and lapatinib. These data support a novel role for RUNX2 in promoting an oncogenic phenotype in luminal BC in the context of TAZ, sE-Cad, and HER2. Using this signaling pathway to monitor BC cell oncogenic activity will accelerate the discovery of new therapeutic modalities to treat BC patients.

Xie J, Yu F, Li D, et al.
MicroRNA-218 regulates cisplatin (DPP) chemosensitivity in non-small cell lung cancer by targeting RUNX2.
Tumour Biol. 2016; 37(1):1197-204 [PubMed] Related Publications
Downregulation of microRNA-218 (miR-218) is found in various human cancers, including non-small cell lung cancer (NSCLC). However, the involvement of chemosensitivity to cisplatin (DDP) and the underlying molecular mechanism remain unclear. In this study, we investigate whether miR-218 mediates NSCLC cell functions associated with chemoresistance. Quantitative real-time polymerase chain reaction (qRT-PCR) was utilized to detect miR-218 expression in NSCLC cell lines A549/DDP and/or A549. The cell activity was measured by MTT assay. Cell cycle and cell apoptosis were detected by flow cytometry. Luciferase reporter assays and Western blots were used to validate runt-related transcription factor 2 (RUNX2) as a direct target gene of miR-218. miR-218 was significantly reduced in A549/DDP cells compared with parent A549 cells. Upregulation of miR-218 altered cell cycle-induced cell apoptosis and enhanced the sensitivity of A549/DDP cells to cisplatin. Mechanistically, RUNX2 was identified as a direct and functional target of miR-218, and RUNX2 executed the former on lung cancer chemoresistance. Our present study demonstrated for the first time that downregulation of miR-218 may contribute to the chemoresistance of NSCLC cells to cisplatin, which leads to upregulation of RUNX2. Uncovering the mechanism represents a novel approach to enhance the efficacy of chemotherapy during cancer treatment.

Feng R, Dong L
Knockdown of microRNA-127 reverses adriamycin resistance via cell cycle arrest and apoptosis sensitization in adriamycin-resistant human glioma cells.
Int J Clin Exp Pathol. 2015; 8(6):6107-16 [PubMed] Free Access to Full Article Related Publications
The aim of this study was to investigate signaling pathways for reversal of microRNA-127-mediated multi-drug resistance (MDR) in gliomas cells. Adriamycin-resistant glioma cell lines U251/adr and U87-MG/adr were established and we found that anti-microRNA-127 markedly reduced microRNA-127 expression levels in a time-dependent manner, leading to distinct inhibition of cell proliferation and increased apoptosis and the content of intracellular Rh123. Silencing of microRNA-127 significantly increased the sensitivity of U251/ADR and U87-MG/adr cells to adriamycin, compared to cells transfected with negative control siRNA. Silencing of microRNA-127 also significantly reduced the mRNA and protein expression levels of MDR1 and MRP1, which are major ATP-binding cassette (ABC) transporter linked to multi-drug resistance in cancer cells. And Runx2, p53, bcl-2 and survivin, which are important role in cell apoptosis, also markedly changed after microRNA-127 silencing. In addition, down-regulating microRNA-127 decreased the level of phosphorylated-Akt. Our data indicate that down-regulation of micorRNA-127 can trigger apoptosis and overcome drug resistance of gliomas cells. Therefore, this resistance of adriamycin in gliomas can be cancelled by silencing expression of microRNA-127.

Cohen-Solal KA, Boregowda RK, Lasfar A
RUNX2 and the PI3K/AKT axis reciprocal activation as a driving force for tumor progression.
Mol Cancer. 2015; 14:137 [PubMed] Free Access to Full Article Related Publications
From the first reported role of the transcription factor RUNX2 in osteoblast and chondrocyte differentiation and migration to its involvement in promigratory/proinvasive behavior of breast, prostate, and thyroid cancer cells, osteosarcoma, or melanoma cells, RUNX2 currently emerges as a key player in metastasis. In this review, we address the interaction of RUNX2 with the PI3K/AKT signaling pathway, one of the critical axes controlling cancer growth and metastasis. AKT, either by directly phosphorylating/activating RUNX2 or phosphorylating/inactivating regulators of RUNX2 stability or activity, contributes to RUNX2 transcriptional activity. Reciprocally, the activation of the PI3K/AKT pathway by RUNX2 regulation of its different components has been described in non-transformed and transformed cells. This mutual activation in the context of cancer cells exhibiting constitutive AKT activation and high levels of RUNX2 might constitute a major driving force in tumor progression and aggressiveness.

Nesbitt H, Browne G, O'Donovan KM, et al.
Nitric Oxide Up-Regulates RUNX2 in LNCaP Prostate Tumours: Implications for Tumour Growth In Vitro and In Vivo.
J Cell Physiol. 2016; 231(2):473-82 [PubMed] Related Publications
Aberrant expression of the transcription factor RUNX2 in prostate cancer has a number of important consequences including increased resistance to apoptosis, invasion and metastasis to bone. We previously demonstrated that hypoxia up-regulated RUNX2 in tumour cells, which in turn up-regulated the anti-apoptotic factor Bcl-2. Here, we investigate the impact of nitric oxide (NO) on RUNX2 and Bcl-2 expression in prostate cancer and further, how RUNX2 over-expression can impact tumour growth, angiogenesis and oxygenation in vivo. The effect of NO levels on RUNX2 and thus Bcl-2 expression was examined in prostate cancer cells in vitro using methods including gene and protein expression analyses, nitrite quantitation, protein-DNA interaction assays (ChIP) and viability assays (XTT). The effect of RUNX2 over-expression on tumour physiology (growth, oxygenation and angiogenesis) was also assessed in vivo using LNCaP xenografts. A low (but not high) concentration of NO (10 μM) induced expression of RUNX2 and Bcl-2, conferring resistance to docetaxel. These effects were induced via the ERK and PI3K pathways and were dependent on intact AP-1 binding sites in the RUNX2 promoter. RUNX2 over-expression in LNCaP tumours in vivo decreased the time to tumour presentation and increased tumour growth. Moreover, these tumours exhibited improved tumour angiogenesis and oxygenation. Low levels of NO increase expression of RUNX2 and Bcl-2 in LNCaP prostate tumour cells, and in vivo up-regulation of RUNX2 created tumours with a more malignant phenotype. Collectively, our data reveals the importance of NO-regulation of key factors in prostate cancer disease progression.

Du Pisani LA, Shires K
Development of a flow cytometric method to detect the presence of mutated nucleophosmin 1 in acute myeloid leukemia.
Hematol Oncol Stem Cell Ther. 2015; 8(3):106-14 [PubMed] Related Publications
OBJECTIVE/BACKGROUND: Nucleophosmin 1 (NPM1) plays multiple roles in cell growth and proliferation. Deletion/insertion mutations in exon 12 of NPM1 (NPM1-DIM), commonly found in patients with acute myeloid leukemia (AML), alter the C-terminal amino acids and disrupt the normal nucleocytoplasmic shuttling function of the protein, which in turn leads to disease pathogenesis. However, this altered function as a result of NPM1-DIM positivity is actually associated with a significantly better response to therapy and overall survival, and thus it is of clinical relevance to investigate the mutation status at diagnosis. Our objective was to design a reliable flow cytometry assay to detect mutated NPM1 in peripheral blood (PB) samples from AML patients, using a polyclonal mutation-specific antibody.
METHODS: A commercially available NPM1 mutation-specific polyclonal antibody in combination with a secondary goat antirabbit antibody was used to detect the C-terminal-mutated NPM1 by flow cytometry. OCI/AML3 (+) cell line and clinical PB controls were used to optimize the assay and determine sensitivity, reliability, and reproducibility parameters. The assay was then tested on a small cohort of 12 AML patients at diagnosis and compared with NPM1-DIM testing on a standard polymerase chain reaction (PCR) platform.
RESULTS: Flow cytometry using the polyclonal antibody was able to reliably detect mutated NPM1 populations of at least 10%. Using an objective analysis of the mean fluorescent intensity, clear positive and negative mutated cell populations could be distinguished using the clinical AML samples. From the analysis of 12 patients, 2 were found to be positive using this assay, which corresponded with conventional PCR methodology.
CONCLUSIONS: Flow cytometry may be used to detect NPM1 C-terminal mutations in AML patients using a polyclonal anti-NPM1 antibody, allowing rapid mutation status determination at diagnosis.

Ratajczak-Wielgomas K, Dziegiel P
The role of periostin in neoplastic processes.
Folia Histochem Cytobiol. 2015; 53(2):120-32 [PubMed] Related Publications
Periostin, also called osteoblast-specific factor 2 (OSF-2), is a multifunctional glycoprotein that belongs to the group of matricellular proteins. Due to its characteristic molecular structure containing integrin-binding domains, periostin is capable of binding to multiple integrin receptors (αvβ3, αvβ5, α6β4), thus affecting the regulation of the intracellular signaling pathways associated with protein kinases PI3K/AKT and focal adhesion kinase (FAK). This protein thus plays a role in the adhesion process, in the migration of many cells, and importantly, epithelial-mesenchymal transition of cancer cells. Periostin also participates in the processes of angiogenesis and lymphangiogenesis, metastases of cancer cells, and remodeling of the extracellular matrix. Increased expression of periostin has been observed in various tumor types, including breast, NSCLC, colorectal, pancreatic, prostate, and ovarian cancers, as well as tumors of the head and neck, and glioblastomas. Many groups have recently reported on periostin's key role in tumor progression, which suggests that periostin can be considered a potential therapeutic target.

Li XQ, Du X, Li DM, et al.
ITGBL1 Is a Runx2 Transcriptional Target and Promotes Breast Cancer Bone Metastasis by Activating the TGFβ Signaling Pathway.
Cancer Res. 2015; 75(16):3302-13 [PubMed] Related Publications
Bone metastasis affects more than 70% of advanced breast cancer patients, but the molecular mechanisms of this process remain unclear. Here, we present clinical and experimental evidence to clarify the role of the integrin β-like 1 (ITGBL1) as a key contributor to bone metastasis of breast cancer. In an in vivo model system and in vitro experiments, ITGBL1 expression promoted formation of osteomimetic breast cancers, facilitating recruitment, residence, and growth of cancer cells in bone microenvironment along with osteoclast maturation there to form osteolytic lesions. Mechanistic investigations identified the TGFβ signaling pathway as a downstream effector of ITGBL1 and the transcription factor Runx2 as an upstream activator of ITGBL1 expression. In support of these findings, we also found that ITGBL1 was an essential mediator of Runx2-induced bone metastasis of breast cancer. Overall, our results illuminate how bone metastasis occurs in breast cancer, and they provide functional evidence for new candidate biomarkers and therapeutic targets to identify risk, to prevent, and to treat this dismal feature of advanced breast cancer.

Foley JM, Scholten DJ, Monks NR, et al.
Anoikis-resistant subpopulations of human osteosarcoma display significant chemoresistance and are sensitive to targeted epigenetic therapies predicted by expression profiling.
J Transl Med. 2015; 13:110 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Osteosarcoma (OS) is the most common type of solid bone cancer, with latent metastasis being a typical mode of disease progression and a major contributor to poor prognosis. For this to occur, cells must resist anoikis and be able to recapitulate tumorigenesis in a foreign microenvironment. Finding novel approaches to treat osteosarcoma and target those cell subpopulations that possess the ability to resist anoikis and contribute to metastatic disease is imperative. Here we investigate anchorage-independent (AI) cell growth as a model to better characterize anoikis resistance in human osteosarcoma while using an expression profiling approach to identify and test targetable signaling pathways.
METHODS: Established human OS cell lines and patient-derived human OS cell isolates were subjected to growth in either adherent or AI conditions using Ultra-Low Attachment plates in identical media conditions. Growth rate was assessed using cell doubling times and chemoresistance was assessed by determining cell viability in response to a serial dilution of either doxorubicin or cisplatin. Gene expression differences were examined using quantitative reverse-transcription PCR and microarray with principal component and pathway analysis. In-vivo OS xenografts were generated by either subcutaneous or intratibial injection of adherent or AI human OS cells into athymic nude mice. Statistical significance was determined using student's t-tests with significance set at α=0.05.
RESULTS: We show that AI growth results in a global gene expression profile change accompanied by significant chemoresistance (up to 75 fold, p<0.05). AI cells demonstrate alteration of key mediators of mesenchymal differentiation (β-catenin, Runx2), stemness (Sox2), proliferation (c-myc, Akt), and epigenetic regulation (HDAC class 1). AI cells were equally tumorigenic as their adherent counterparts, but showed a significantly decreased rate of growth in-vitro and in-vivo (p<0.05). Treatment with the pan-histone deacetylase inhibitor vorinostat and the DNA methyltransferase inhibitor 5-azacytidine mitigated AI growth, while 5-azacytidine sensitized anoikis-resistant cells to doxorubicin (p<0.05).
CONCLUSIONS: These data demonstrate remarkable plasticity in anoikis-resistant human osteosarcoma subpopulations accompanied by a rapid development of chemoresistance and altered growth rates mirroring the early stages of latent metastasis. Targeting epigenetic regulation of this process may be a viable therapeutic strategy.

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