Overexpression of runt-related transcription factor-2 is associated with advanced tumor progression and poor prognosis in epithelial ovarian cancer

Pharmacological inhibition of protein kinase D suppresses epithelial ovarian cancer via MAPK/ERK1/2/Runx2 signalling axis

Epithelial ovarian cancer (EOC) is the most lethal gynaecological malignancy with poor prognosis and dismal patient survival. Although protein kinase D (PKD) isoforms, especially PKD2 and PKD3 are critical for many cellular and physiological functions involved in carcinogenesis including cell proliferation and angiogenesis, their role in human EOC remains unknown. Towards the goal to identify novel prognostic biomarker and therapeutic interventions against EOC, this study aimed to elucidate the molecular roles of PKD2, PKD3 and highly selective, pan-PKD inhibitor CRT0066101 in this lethal pathology. Our results indicated that inactivation of PKD2 and PKD3 by 1 μM CRT0066101 suppressed EOC cell proliferation, colony formation, cell migration and invasion. Moreover, CRT0066101 induced apoptosis and inhibited cell cycle at G2-M phase in EOC cells. Genetic knockdown of PKD2 and PKD3 confirmed the anti-carcinogenic effects of CRT0066101 against EOC. The anti-cancer phenotype of EOC cells resulted from CRT0066101-mediated PKD2 and PKD3 inactivation or genetic depletion was, in part, mediated by transcription factor Runx2 as abrogation of PKD2 and PKD3 caused downregulation of Runx2 and its downstream target genes including osteopontin, focal adhesion kinase and ERK1/2. Moreover, overexpression of a constitutively active PKD2 augmented the expression levels of phosphor-ERK1/2T202/Y204, Runx2 and its downstream targets. Mechanistically, PKD2 and PKD3 positively regulated Runx2 via MAPK/ERK1/2 pathway and promoted EOC. Taken together, our results indicated that PKD2/3/ERK1/2/Runx2 signalling axis might be a novel drug target against EOC and CRT0066101 could be developed as a promising therapeutic choice against this lethal pathology.

Induction of ALP and MMP9 activity facilitates invasive behavior in heterogeneous human BMSC and HNSCC 3D spheroids

Mesenchymal stem cells (MSCs) are multipotent progenitor cells capable of differentiating into adipocytic, osteogenic, chondrogenic, and myogenic lineages. There is growing evidence that MSCs home into the tumor microenvironment attracted by a variety of signals such as chemokines, growth factors, and cytokines. Tumor-homing stem cells may originate from bone marrow-derived MSCs (BMSCs) or adipose tissue-derived MSCs. Recent scientific data suggest that MSCs in combination with tumor cells can either promote or inhibit tumorigenic behavior. In head and neck squamous cell carcinoma (HNSCC), BMSCs are reported to be enriched with a potential negative role. Here, we evaluated the effect of BMSCs from 4 different donors in combination with 4 HNSCC cell lines in a 3-dimensional multicellular spheroid model. Heterogeneous combinations revealed an up-regulation of gene and protein expression of osteogenic markers runt-related transcription factor 2 (RUNX2) and alkaline phosphatase (ALP) together with a substantial secretion of matrix metalloproteinase 9. Moreover, heterogenous BMSC/tumor spheroids showed increased invasion compared with homogenous spheroids in a Boyden chamber invasion assay. Furthermore, inhibition of ALP resulted in a substantially decreased spreading of heterogeneous spheroids on laminin-rich matrix. In summary, our data suggest a prometastatic effect of BMSCs combined with HNSCC.-Wessely, A., Waltera, A., Reichert, T. E., Stöckl, S., Grässel, S., Bauer, R. J. Induction of ALP and MMP9 activity facilitates invasive behavior in heterogeneous human BMSC and HNSCC 3D-spheroids.

Expression of tissue factor in human cervical carcinoma tissue

The present study aimed to investigate tissue factor (TF) expression in cervical cancer and explore its association with disease progression. A total of 258 cervical cancer tissues and their adjacent normal tissues were collected between September 2014 and September 2016. TF expression was detected in the tissue samples by immunohistochemistry and western blot analysis. Associations between the expression of TF and clinical stage, differentiation status and metastasis of cancer cells were examined. The mean immunohistochemistry score of TF expression in cervical cancer tissues was 2.86±1.76, which was significantly increased compared with the adjacent normal tissues (0.28±0.45). The expression of TF was also significantly associated with the clinical stage, lymph node metastasis and distant metastasis of cancer cells. Immunohistochemistry staining and western blot analysis demonstrated that TF expression in cervical cancer tissues significantly increased as the clinical stage increased. TF expression in tumor tissues from patients with lymph node metastasis was significantly increased compared with samples from patients without lymph node metastasis. TF expression was also significantly increased in patients with distant metastasis compared with those without. In conclusion, TF is highly expressed in cervical cancer tissues and high expression of TF may enhance the invasion and metastasis of cervical cancer cells.

MicroRNA-218 inhibits proliferation and invasion in ovarian cancer by targeting Runx2

MicroRNA-218 (miR-218) has been implicated in the development and progression of multiple cancers. We investigated the role of miR-218 in ovarian cancer progression. We found that miR-218 expression levels were lower in ovarian cancer tissues and cell lines than in adjacent normal tissues or a normal ovarian cell line.miR-218 levels associated with International Federation of Gynecology and Obstetrics (FIGO) stage and lymph node metastasis. Exogenous expression of miR-218 inhibited cell proliferation, colony formation, migration, and invasion in vitro and suppressed tumor growth in a tumor-bearing nude mouse model. Runt-related transcription factor 2 (RUNX2) was identified as a direct functional target of miR-218, and its expression was inversely correlated with miR-218 expression in ovarian cancer tissues. RUNX2 overexpression rescued the suppressive effect of miR-218 on ovarian cancer cell proliferation, colony formation, migration, and invasion. These findings highlight an important role played bymiR-218 in the regulation of cancer growth and metastasis, in part by repressing RUNX2, and revealed the potential of miR-218 as a new therapeutic target inovarian cancer.

High Coexpression of Runt-related Transcription Factor 2 (RUNX2) and p53 Independently Predicts Early Tumor Recurrence in Bladder Urothelial Carcinoma Patients

Conventional prognostic factors for bladder cancer are inadequate to predict tumor recurrence and/or progression successfully; thus, the identification of adjunctive novel prognostic biomarkers is of paramount importance. In this study, the immunohistochemical expression patterns and clinical significance of RUNX2, WWOX, and p53 were investigated in a tissue microarray of 87 primary urothelial carcinomas and 17 control cases. We found that RUNX2, WWOX, and p53 were significantly correlated and overexpressed in urothelial carcinoma cases compared with the control group. RUNX2 and p53 were significantly upregulated in association with high-grade, nonpapillary pattern, and bilharziasis. Muscle-invasive tumors significantly overexpressed RUNX2. WWOX overexpression was significantly associated with high-grade tumors and inversely correlated with age. In a bivariate analysis, the risk of early tumor recurrence and progression was significantly associated with RUNX2 and p53 overexpression and bilharziasis. A multivariate Cox regression analysis proved that RUNX2 and p53 were independent predictors of early tumor recurrence. The ROC curve analysis showed that combined RUNX2 and p53 high expression (scores >3 and >5, respectively) had the highest accuracy (73.6%) for the prediction of early tumor recurrence. We conclude that RUNX2 and p53 might be functionally related and are likely involved in bladder tumor carcinogenesis and aggressiveness, which provides a new perspective for targeted therapy. RUNX2 and p53 independently predict early tumor recurrence in bladder carcinoma patients, with the highest prediction accuracy being achieved on their combined high expression. The role of WWOX in bladder urothelial carcinoma and its relationship with RUNX2 and p53 remains unclear and warrants further investigation.

The enigmatic role of RUNX1 in female-related cancers - current knowledge & future perspectives

Historically associated with the aetiology of human leukaemia, the runt-related transcription factor 1 (RUNX1) gene has in recent years reared its head in an assortment of epithelial cancers. This review discusses the state-of-the-art knowledge of the enigmatic role played by RUNX1 in female-related cancers of the breast, the uterus and the ovary. The weight of evidence accumulated so far is indicative of a very context-dependent role, as either an oncogene or a tumour suppressor. This is corroborated by high-throughput sequencing endeavours which report different genetic alterations affecting the gene, including amplification, deep deletion and mutations. Herein, we attempt to dissect that contextual role by firstly giving an overview of what is currently known about RUNX1 function in these specific tumour types, and secondly by delving into connections between this transcription factor and the physiology of these female tissues. In doing so, RUNX1 emerges not only as a gene involved in female sex development but also as a crucial mediator of female hormone signalling. In view of RUNX1 now being listed as a driver gene, we believe that greater knowledge of the mechanisms underlying its functional dualism in epithelial cancers is worthy of further investigation.

Association of genetic polymorphisms with survival of pancreatic ductal adenocarcinoma patients

Germline genetic variability might contribute, at least partially, to the survival of pancreatic ductal adenocarcinoma (PDAC) patients. Two recently performed genome-wide association studies (GWAS) on PDAC overall survival (OS) suggested (P < 10(-5)) the association between 30 genomic regions and PDAC OS. With the aim to highlight the true associations within these regions, we analyzed 44 single-nucleotide polymorphisms (SNPs) in the 30 candidate regions in 1722 PDAC patients within the PANcreatic Disease ReseArch (PANDoRA) consortium. We observed statistically significant associations for five of the selected regions. One association in the CTNNA2 gene on chromosome 2p12 [rs1567532, hazard ratio (HR) = 1.75, 95% confidence interval (CI) 1.19-2.58, P = 0.005 for homozygotes for the minor allele] and one in the last intron of the RUNX2 gene on chromosome 6p21 (rs12209785, HR = 0.88, 95% CI 0.80-0.98, P = 0.014 for heterozygotes) are of particular relevance. These loci do not coincide with those that showed the strongest associations in the previous GWAS. In silico analysis strongly suggested a possible mechanistic link between these two SNPs and pancreatic cancer survival. Functional studies are warranted to confirm the link between these genes (or other genes mapping in those regions) and PDAC prognosis in order to understand whether these variants may have the potential to impact treatment decisions and design of clinical trials.

MicroRNA-217 inhibits cell proliferation and invasion by targeting Runx2 in human glioma

MircroRNA-217 (miR-217) has been showed to involve in the initiation and development of human cancers, and is recognize as a tumor suppressor miRNA in several tumors. However, the clinical significance and its underlying role in human glioma remain unclear. Herein, we found that the expression of miR-217 was significantly down-regulated in glioma tissues as compared with adjacent normal brain tissues. Clinical association analysis disclosed that low-expression of miR-217 was evidently negative associated with advanced tumor stage (grade III + IV) in glioma. Further function assays showed that miR-217 inhibited proliferation, colony formation, invasion and migration of glioma cells. Notably, runt-related transcription factors 2 (Runx2) was identified as a functional target of miR-217 in glioma. Furthermore, an inverse correlation between miR-217 and Runx2 expression was observed in glioma tissues. Downregulation of Runx2 has similar with inhibition effect of overexpression of miR-217, and upregulation of Runx2 reversed the effects of overexpressing of miR-217. Taken together, these results suggest a critical role of miR-217 in suppressing proliferation, migration, and invasion of glioma by targeting Runx2.

Silencing of RUNX2 enhances gemcitabine sensitivity of p53-deficient human pancreatic cancer AsPC-1 cells through the stimulation of TAp63-mediated cell death

Runt-related transcription factor 2 (RUNX2) has been considered to be one of master regulators for osteoblast differentiation and bone formation. Recently, we have described that RUNX2 attenuates p53/TAp73-dependent cell death of human osteosarcoma U2OS cells bearing wild-type p53 in response to adriamycin. In this study, we have asked whether RUNX2 silencing could enhance gemcitabine (GEM) sensitivity of p53-deficient human pancreatic cancer AsPC-1 cells. Under our experimental conditions, GEM treatment increased the expression level of p53 family TAp63, whereas RUNX2 was reduced following GEM exposure, indicating that there exists an inverse relationship between the expression level of TAp63 and RUNX2 following GEM exposure. To assess whether TAp63 could be involved in the regulation of GEM sensitivity of AsPC-1 cells, small interfering RNA-mediated knockdown of TAp63 was performed. As expected, silencing of TAp63 significantly prohibited GEM-dependent cell death as compared with GEM-treated non-silencing cells. As TAp63 was negatively regulated by RUNX2, we sought to examine whether RUNX2 knockdown could enhance the sensitivity to GEM. Expression analysis demonstrated that depletion of RUNX2 apparently stimulates the expression of TAp63, as well as proteolytic cleavage of poly ADP ribose polymerase (PARP) after GEM exposure, and further augmented GEM-mediated induction of p53/TAp63-target genes, such as p21^WAF1, PUMA and NOXA, relative to GEM-treated control-transfected cells, implying that RUNX2 has a critical role in the regulation of GEM resistance through the downregulation of TAp63. Notably, ablation of TAp63 gave a decrease in number of γH2AX-positive cells in response to GEM relative to control-transfected cells following GEM exposure. Consistently, GEM-dependent phosphorylation of ataxia telangiectasia-mutated protein was remarkably impaired in TAp63 knockdown cells. Collectively, our present findings strongly suggest that RUNX2-mediated repression of TAp63 contributes at least in part to GEM resistance of AsPC-1 cells, and thus silencing of RUNX2 may be a novel strategy to enhance the efficacy of GEM in p53-deficient pancreatic cancer cells.

Knockdown of microRNA-127 reverses adriamycin resistance via cell cycle arrest and apoptosis sensitization in adriamycin-resistant human glioma cells

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.

Myeloma cell-derived Runx2 promotes myeloma progression in bone

The progression of multiple myeloma (MM) is governed by a network of molecular signals, the majority of which remain to be identified. Recent studies suggest that Runt-related transcription factor 2 (Runx2), a well-known bone-specific transcription factor, is also expressed in solid tumors, where expression promotes both bone metastasis and osteolysis. However, the function of Runx2 in MM remains unknown. The current study demonstrated that (1) Runx2 expression in primary human MM cells is significantly greater than in plasma cells from healthy donors and patients with monoclonal gammopathy of undetermined significance; (2) high levels of Runx2 expression in MM cells are associated with a high-risk population of MM patients; and (3) overexpression of Runx2 in MM cells enhanced tumor growth and disease progression in vivo. Additional studies demonstrated that MM cell-derived Runx2 promotes tumor progression through a mechanism involving the upregulation of Akt/β-catenin/Survivin signaling and enhanced expression of multiple metastatic genes/proteins, as well as the induction of a bone-resident cell-like phenotype in MM cells. Thus, Runx2 expression supports the aggressive phenotype of MM and is correlated with poor prognosis. These data implicate Runx2 expression as a major regulator of MM progression in bone and myeloma bone disease.

miR‑338‑3p suppresses tumor growth of ovarian epithelial carcinoma by targeting Runx2

miR‑338‑3p, a recently discovered miRNA, has been shown to play important roles in tumorigenesis and metastasis in various cancers. However, the exact roles and mechanisms of miR‑338‑3p remain unknown in human ovarian epithelial carcinoma (EOC). The relationship between miR‑338‑3p expression pattern and clinicopathological features of patients with EOC were determined by real-time quantitative RT-PCR. Furthermore, the role of miR‑338‑3p and possible molecular mechanisms in EOC was investigated by several in vitro approaches and in a nude mouse model. We first showed that the expression of miR‑338‑3p was significantly downregulated in EOC tissues compared to those in adjacent normal tissues, and the value was negatively related to advanced FIGO stage, high histological grading and lymph node metastasis (P<0.01). An in vitro analysis revealed that the overexpression of miR‑338‑3p in EOC cells significantly inhibited cell proliferation, colony formation, migration and invasion, inducing cell apoptosis and enhancing caspase-3, -8, and -9 activities. Bioinformatic analysis and dual luciferase assays identified Runx2 as a direct target of miR‑338‑3p. We also found that enforced expression of miR‑338‑3p markedly inhibited the in vivo tumorigenicity in a nude mouse xenograft model system. Furthermore, overexpression of miR‑338‑3p inhibited phosphorylation of PI3K and AKT, which contributed to suppression of ovarian cancer cell growth. These findings revealed that miR‑338‑3p may act as a tumor suppressor that blocks the growth of human ovarian epithelial carcinoma through PI3K/AKT signaling pathways by targeting Runx2.

Histone Deacetylase Inhibitors Repress Tumoral Expression of the Proinvasive Factor RUNX2

Aberrant reactivation of embryonic pathways occurs commonly in cancer. The transcription factor RUNX2 plays a fundamental role during embryogenesis and is aberrantly reactivated during progression and metastasization of different types of human tumors. In this study, we attempted to dissect the molecular mechanisms governing RUNX2 expression and its aberrant reactivation. We identified a new regulatory enhancer element, located within the RUNX2 gene, which is responsible for the activation of the RUNX2 promoter and for the regulation of its expression in cancer cells. Furthermore, we have shown that treatment with the anticancer compounds histone deacetylase inhibitor (HDACi) results in a profound inhibition of RUNX2 expression, which is determined by the disruption of the transcription-activating complex on the identified enhancer. These data envisage a possible targeting strategy to counteract the oncongenic function of RUNX2 in cancer cells and provide evidence that the cytotoxic activity of HDACi in cancer is not only dependent on the reactivation of silenced oncosuppressors but also on the repression of oncogenic factors that are necessary for survival and progression.

The prognostic significance of RUNX2 and miR-10a/10b and their inter-relationship in breast cancer

Background

The major cancer related mortality is caused by metastasis and invasion. It is important to identify genes regulating metastasis and invasion in order to curtail metastatic spread of cancer cells.

Methods

This study investigated the association between RUNX2 and miR-10a/miR-10b and the risk of breast cancer relapse. Expression levels of RUNX2 and miR-10a/b in108 pairs of tumor and non-tumor tissue of breast cancer were assayed by quantitative PCR analysis and evaluated for their prognostic implications.

Results

The median expression levels of RUNX2 and miR-10b in tumor tissue normalized using adjacent non-tumor tissue were significantly higher in relapsed patients than in relapse-free patients. Higher expression of these three genes were significantly correlated with the hazard ratio for breast cancer recurrence (RUNX2: 3.02, 95% CI = 1.50 ~ 6.07; miR-10a: 2.31, 95% CI = 1.00 ~ 5.32; miR-10b: 3.96, 95% CI = 1.21 ~ 12.98). The joint effect of higher expression of all three genes was associated with a hazard ratio of 12.37 (95% CI = 1.62 ~ 94.55) for relapse. In a breast cancer cell line, RUNX2 silencing reduced the expression of miR-10a/b and also impaired cell motility, while RUNX2 overexpression elicited opposite effects.

Conclusions

These findings indicate that higher expression of RUNX2 and miR-10a/b was associated with adverse outcome of breast cancer. Expression levels of RUNX2 and miR-10a/b individually or jointly are potential prognostic factors for predicting breast cancer recurrence. Data from in vitro studies support the notion that RUNX2 promoted cell motility by upregulating miR-10a/b.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-014-0257-3) contains supplementary material, which is available to authorized users.

MicroRNA-23b is an independent prognostic marker and suppresses ovarian cancer progression by targeting runt-related transcription factor-2

Our previous study found that runt-related transcription factor-2 (RUNX2) was upregulated in human epithelial ovarian cancer (EOC) tissues and may be involved in tumor progression and prognosis. The aim of this study was to investigate the mechanism by which RUNX2 is aberrantly expressed in EOC. We firstly confirmed that miRNA-23b directly targets RUNX2 in EOC. Then, ectopic expression of miR-23b significantly inhibited ovarian cancer cell proliferation and tumorigenicity by regulating the expression of RUNX2. Furthermore, the down-regulation of miR-23b was significantly correlated with tumor aggressiveness and poor prognosis of patients with EOC. Collectively, miR-23b may function as tumor suppressor through inhibiting the upregulation of RUNX2, and may be a potential prognostic marker for EOC.

Runx2 activates PI3K/Akt signaling via mTORC2 regulation in invasive breast cancer cells

Introduction

The Runt-related transcription factor Runx2 is critical for skeletal development but is also aberrantly expressed in breast cancers, and promotes cell growth and invasion. A de-regulated serine/threonine kinase Akt signaling pathway is implicated in mammary carcinogenesis and cell survival; however, the mechanisms underlying Runx2 role in survival of invasive breast cancer cells are still unclear.

Methods

The phenotypic analysis of Runx2 function in cell survival was performed by gene silencing and flow cytometric analysis in highly invasive MDA-MB-231 and SUM-159-PT mammary epithelial cell lines. The expression analysis of Runx2 and pAkt (serine 473) proteins in metastatic breast cancer specimens was performed by immunohistochemistry. The mRNA and protein levels of kinases and phosphatases functional in Akt signaling were determined by real-time PCR and Western blotting, while DNA-protein interaction was studied by chromatin immunoprecipitation assays.

Results

The high Runx2 levels in invasive mammary epithelial cell lines promoted cell survival in Akt phosphorylation (pAkt-serine 473) dependent manner. The analysis of kinases and phosphatases associated with pAkt regulation revealed that Runx2 promotes pAkt levels via mammalian target of rapamycin complex-2 (mTORC2). The recruitment of Runx2 on mTOR promoter coupled with Runx2-dependent expression of mTORC2 component Rictor defined Runx2 function in pAkt-mediated survival of invasive breast cancer cells.

Conclusions

Our results identified a novel mechanism of Runx2 regulatory crosstalk in Akt signaling that could have important consequences in targeting invasive breast cancer-associated cell survival.

Inhibition of RUNX2 transcriptional activity blocks the proliferation, migration and invasion of epithelial ovarian carcinoma cells

Previously, we have identified the RUNX2 gene as hypomethylated and overexpressed in post-chemotherapy (CT) primary cultures derived from serous epithelial ovarian cancer (EOC) patients, when compared to primary cultures derived from matched primary (prior to CT) tumors. However, we found no differences in the RUNX2 methylation in primary EOC tumors and EOC omental metastases, suggesting that DNA methylation-based epigenetic mechanisms have no impact on RUNX2 expression in advanced (metastatic) stage of the disease. Moreover, RUNX2 displayed significantly higher expression not only in metastatic tissue, but also in high-grade primary tumors and even in low malignant potential tumors. Knockdown of the RUNX2 expression in EOC cells led to a sharp decrease of cell proliferation and significantly inhibited EOC cell migration and invasion. Gene expression profiling and consecutive network and pathway analyses confirmed these findings, as various genes and pathways known previously to be implicated in ovarian tumorigenesis, including EOC tumor invasion and metastasis, were found to be downregulated upon RUNX2 suppression, while a number of pro-apoptotic genes and some EOC tumor suppressor genes were induced. Taken together, our data are indicative for a strong oncogenic potential of the RUNX2 gene in serous EOC progression and suggest that RUNX2 might be a novel EOC therapeutic target. Further studies are needed to more completely elucidate the functional implications of RUNX2 and other members of the RUNX gene family in ovarian tumorigenesis.

Evolution, ovulation and cancer

Secretions by epithelial cells of the fallopian tube regulate ovulation through conserved pathways, which means that experiments on flies might provide insights into the human reproductive system and, possibly, ovarian cancer.

The RUNX1 transcription factor is expressed in serous epithelial ovarian carcinoma and contributes to cell proliferation, migration and invasion

Previously, we have identified the RUNX1 gene as hypomethylated and overexpressed in post-chemotherapy (CT) primary cultures derived from epithelial ovarian cancer (EOC) patients, when compared with primary cultures derived from matched primary (prior to CT) tumors. Here we show that RUNX1 displays a trend of hypomethylation, although not significant, in omental metastases compared with primary EOC tumors. Surprisingly, RUNX1 displayed significantly higher expression not only in metastatic tissue, but also in high-grade primary tumors and even in low malignant potential tumors. The RUNX1 expression levels were almost identical in primary tumors and omental metastases, suggesting that RUNX1 hypomethylation might have a limited impact on its overexpression in advanced (metastatic) stage of the disease. Knockdown of the RUNX1 expression in EOC cells led to sharp decrease of cell proliferation and induced G 1 cell cycle arrest. Moreover, RUNX1 suppression significantly inhibited EOC cell migration and invasion. Gene expression profiling and consecutive network and pathway analyses confirmed these findings, as numerous genes and pathways known previously to be implicated in ovarian tumorigenesis, including EOC tumor invasion and metastasis, were found to be downregulated upon RUNX1 suppression, while a number of pro-apoptotic genes and some EOC tumor suppressor genes were induced. Taken together, our data are indicative for a strong oncogenic potential of the RUNX1 gene in EOC progression and suggest that RUNX1 might be a novel EOC therapeutic target. Further studies are needed to more completely elucidate the functional implications of RUNX1 and other members of the RUNX gene family in ovarian tumorigenesis.