Inactivation Of RUNX3 Research Articles

RUNX3 Meets the Ubiquitin-Proteasome System in Cancer

RUNX3 is a transcription factor with regulatory roles in cell proliferation and development. While largely characterized as a tumor suppressor, RUNX3 can also be oncogenic in certain cancers. Many factors account for the tumor suppressor function of RUNX3, which is reflected by its ability to suppress cancer cell proliferation after expression-restoration, and its inactivation in cancer cells. Ubiquitination and proteasomal degradation represent a major mechanism for the inactivation of RUNX3 and the suppression of cancer cell proliferation. On the one hand, RUNX3 has been shown to facilitate the ubiquitination and proteasomal degradation of oncogenic proteins. On the other hand, RUNX3 can be inactivated through the ubiquitin-proteasome system. This review encapsulates two facets of RUNX3 in cancer: how RUNX3 suppresses cell proliferation by facilitating the ubiquitination and proteasomal degradation of oncogenic proteins, and how RUNX3 is degraded itself through interacting RNA-, protein-, and pathogen-mediated ubiquitination and proteasomal degradation.

Role of RUNX3 in Restriction Point Regulation

A cell cycle is a series of events that takes place in a cell as it grows and divides. At the G1 phase of cell cycle, cells monitor their cumulative exposure to specific signals and make the critical decision to pass through the restriction (R)-point. The R-point decision-making machinery is fundamental to normal differentiation, apoptosis, and G1-S transition. Deregulation of this machinery is markedly associated with tumorigenesis. Therefore, identification of the molecular mechanisms that govern the R-point decision is one of the fundamental issues in tumor biology. RUNX3 is one of the genes frequently inactivated in tumors by epigenetic alterations. In particular, RUNX3 is downregulated in most K-RAS-activated human and mouse lung adenocarcinomas (ADCs). Targeted inactivation of Runx3 in the mouse lung induces adenomas (ADs), and markedly shortens the latency of ADC formation induced by oncogenic K-Ras. RUNX3 participates in the transient formation of R-point-associated activator (RPA-RX3-AC) complexes, which measure the duration of RAS signals and thereby protect cells against oncogenic RAS. This review focuses on the molecular mechanism by which the R-point participates in oncogenic surveillance.

RUNX3 methylation drives hypoxia-induced cell proliferation and antiapoptosis in early tumorigenesis

Inactivation of tumor suppressor Runt-related transcription factor 3 (RUNX3) plays an important role during early tumorigenesis. However, posttranslational modifications (PTM)-based mechanism for the inactivation of RUNX3 under hypoxia is still not fully understood. Here, we demonstrate a mechanism that G9a, lysine-specific methyltransferase (KMT), modulates RUNX3 through PTM under hypoxia. Hypoxia significantly increased G9a protein level and G9a interacted with RUNX3 Runt domain, which led to increased methylation of RUNX3 at K129 and K171. This methylation inactivated transactivation activity of RUNX3 by reducing interactions with CBFβ and p300 cofactors, as well as reducing acetylation of RUNX3 by p300, which is involved in nucleocytoplasmic transport by importin-α1. G9a-mediated methylation of RUNX3 under hypoxia promotes cancer cell proliferation by increasing cell cycle or cell division, while suppresses immune response and apoptosis, thereby promoting tumor growth during early tumorigenesis. Our results demonstrate the molecular mechanism of RUNX3 inactivation by G9a-mediated methylation for cell proliferation and antiapoptosis under hypoxia, which can be a therapeutic or preventive target to control tumor growth during early tumorigenesis.

K-Ras-Activated Cells Can Develop into Lung Tumors When Runx3-Mediated Tumor Suppressor Pathways Are Abrogated.

K-RAS is frequently mutated in human lung adenocarcinomas (ADCs), and the p53 pathway plays a central role in cellular defense against oncogenic K-RAS mutation. However, in mouse lung cancer models, oncogenic K-Ras mutation alone can induce ADCs without p53 mutation, and loss of p53 does not have a significant impact on early K-Ras–induced lung tumorigenesis. These results raise the question of how K-Ras–activated cells evade oncogene surveillance mechanisms and develop into lung ADCs. RUNX3 plays a key role at the restriction (R)-point, which governs multiple tumor suppressor pathways including the p14ARF–p53 pathway. In this study, we found that K-Ras activation in a very limited number of cells, alone or in combination with p53 inactivation, failed to induce any pathologic lesions for up to 1 year. By contrast, when Runx3 was inactivated and K-Ras was activated by the same targeting method, lung ADCs and other tumors were rapidly induced. In a urethane-induced mouse lung tumor model that recapitulates the features of K-RAS–driven human lung tumors, Runx3 was inactivated in both adenomas (ADs) and ADCs, whereas K-Ras was activated only in ADCs. Together, these results demonstrate that the R-point–associated oncogene surveillance mechanism is abrogated by Runx3 inactivation in AD cells and these cells cannot defend against K-Ras activation, resulting in the transition from AD to ADC. Therefore, K-Ras–activated lung epithelial cells do not evade oncogene surveillance mechanisms; instead, they are selected if they occur in AD cells in which Runx3 has been inactivated.

RUNX3 inhibits the invasion and migration of esophageal squamous cell carcinoma by reversing the epithelial‑mesenchymal transition through TGF‑β/Smad signaling.

Runt-related transcription factor 3 (RUNX3) is a candidate tumor suppressor, and its inactivation may play a crucial role in the carcinogenesis process of numerous cancer types, including esophageal squamous cell carcinoma (ESCC). We previously revealed that RUNX3 inactivation was correlated with lymph node metastasis (LNM) and ESCC recurrence. However, the exact mechanisms of this process are still under investigation. The aim of the present study was to examine the potential roles and underlying molecular mechanisms of RUNX3 in ESCC metastasis and the epithelial-mesenchymal transition (EMT). According to the results, RUNX3 expression in ESCC tissue was significantly reduced compared with that in adjacent normal tissue (0.50±0.20 vs. 0.83±0.16; P<0.001). In addition, statistical analysis revealed a close association between decreased RUNX3 expression and T status (P=0.027) and LNM (P=0.017) in ESCC patients. Pearson's correlation coefficient analysis was then used to evaluate correlations between RUNX3 and EMT-related marker expression. The results revealed that RUNX3 expression in ESCC tissues was negatively correlated with the expression of N-cadherin (r=−0.429; P<0.01) and Snail (r=−0.364; P<0.01) and positively correlated with the expression of E-cadherin (r=0.580; P<0.01). Moreover, Eca109 and EC9706 cell invasion, migration, MMP-9 expression and EMT were significantly inhibited by RUNX3 overexpression. Notably, further analysis revealed that RUNX3 overexpression markedly inhibited the phosphorylation of Smad2/3; RUNX3-overexpressing cells also displayed less sensitivity to TGF-β1-induced EMT than control cells. Thus, RUNX3 may inhibit the invasion and migration of ESCC cells by reversing EMT through TGF-β/Smad signaling and may be useful as a therapeutic target.

P2.03-25 Loss of Expression Rather Than Cytoplasmic Mislocalization of RUNX3 Predicts Worse Outcome in Non-Small Cell Lung Cancer

Functional inactivation of RUNX3 through epigenetic silencing was well-documented in many cancers. Added to gene mutation and promoter hypermethylation, cytoplasmic mislocalization was another major manifestation of RUNX3 dysfunction in malignancies like gastric cancer. We aimed to investigate whether NSCLC patients with different RUNX3 expression patterns would have differrent OS, and the associations of different patterns with clinicopathologic parameters and clinical outcome. Expressions of RUNX3 and Ki-67 were immunohistochemically detected in normal lung tissue (n=5) and surgically resected NSCLC patients (n=188). The optimal cutoff of RUNX3 was determined by X-tile software related to their survival. Apoptotic index in cancerous tissue was evaluated by TdT mediated dUTP-biotin nick end labelling (TUNEL) method. The prognostic significance of different expression patterns of RUNX3 was determined by means of Kaplan-Meier survival estimates and log-rank tests. Loss of RUNX3 expression in NSCLC was correlated with low cancerous apoptotic index (P<0.001), shorter OS and worse prognosis (P=0.0142), while no statistical difference of apoptotic index (P=0.73) or survival (P=0.3781) had been determined between patient subgroups with different localization of RUNX3 expression. Loss of expression rather than cytoplasmic mislocalization of RUNX3 predicted worse outcome in NSCLC, which was quite different from what it manifested in other cancer types.

TGFβ Promotes Genomic Instability after Loss of RUNX3.

Studies of genomic instability have historically focused on intrinsic mechanisms rather than extrinsic mechanisms based in the tumor microenvironment (TME). TGFβ is the most abundantly secreted cytokine in the TME, where it imparts various aggressive characteristics including invasive migration, drug resistance, and epithelial-to-mesenchymal transition (EMT). Here we show that TGFβ also promotes genomic instability in the form of DNA double strand breaks (DSB) in cancer cells that lack the tumor suppressor gene RUNX3 Loss of RUNX3 resulted in transcriptional downregulation of the redox regulator heme oxygenase-1 (HO-1 or HMOX1). Consequently, elevated oxidative DNA damage disrupted genomic integrity and triggered cellular senescence, which was accompanied by tumor-promoting inflammatory cytokine expression and acquisition of the senescence-associated secretory phenotype (SASP). Recapitulating the above findings, tumors harboring a TGFβ gene expression signature and RUNX3 loss exhibited higher levels of genomic instability. In summary, RUNX3 creates an effective barrier against further TGFβ-dependent tumor progression by preventing genomic instability. These data suggest a novel cooperation between cancer cell-extrinsic TGFβ signaling and cancer cell-intrinsic RUNX3 inactivation as aggravating factors for genomic instability.Significance: RUNX3 inactivation in cancer removes an antioxidant barrier against DNA double strand breaks induced by TGFβ expressed in the tumor microenvironment. Cancer Res; 78(1); 88-102. ©2017 AACR.

CORRIGENDUM: Correction of funding statement in ACKNOWLEDGEMENTS section: Epigenetic inactivation of RUNX3 in colorectal cancer

[This corrects the article on p. 19 in vol. 94, PMID: 29333422.].

Epigenetic inactivation of RUNX3 in colorectal cancer.

PurposeEmerging evidence indicates that runt-related transcription factor 3 (RUNX3) is an important tumor suppressor gene in several cancer types, including colorectal cancer (CRC). However, the clinical significance of RUNX3 inactivation in CRC remains unclear. The aim of this study was to examine the correlation between clinicopathologic factors and RUNX3 hypermethylation/expression in CRC.MethodsSixty-two CRC patients who were treated at the Soonchunhyang University College of Medicine were recruited in this study. The hypermethylation of CpG islands in the RUNX3 promoter and the expression of RUNX3 mRNA were identified by methylation-specific polymerase chain reaction (PCR) and reverse transcriptase-PCR, respectively. The expression of RUNX3 was determined by immunohistochemical staining.ResultsOf the 62 CRC tissue samples, 20 (32.3%) presented hypermethylated RUNX3 promoters. Aberrant RUNX3 hypermethylation was found to be associated with vascular (P = 0.006) and lymphatic (P = 0.002) invasion. Hypermethylation of RUNX3 was associated with poor survival outcomes (P = 0.038). However, expression of RUNX3 was not a prognostic factor (P = 0.363).ConclusionHypermethylation of RUNX3 may be a predictor of a poor prognosis in CRC.

Cytoplasmic Localization of RUNX3 via Histone Deacetylase-Mediated SRC Expression in Oxidative-Stressed Colon Cancer Cells.

Runt domain transcription factor 3 (RUNX3) is a transcription factor that functions as a tumor suppressor. RUNX3 is frequently inactivated by epigenetic silencing or its protein mislocalization (cytoplasmic localization) in many cancer types. This study investigated whether oxidative stress induces redistribution of RUNX3 from the nucleus to the cytoplasm. The cytoplasmic localization of RUNX3 was associated with oxidative stress-induced RUNX3 phosphorylation at tyrosine residues via SRC activation. Moreover, oxidative stress increased expression of histone deacetylases (HDACs). RUNX3 phosphorylation and SRC expression induced by oxidative stress were inhibited by knockdown of HDAC1, restoring the nuclear localization of RUNX3 under oxidative stress. In conclusion, these results demonstrate that HDAC1- and SRC-mediated phosphorylation of RUNX3 induced by oxidative stress is associated with the cytoplasmic localization of RUNX3 and can lead to RUNX3 inactivation and carcinogenesis. J. Cell. Physiol. 232: 1914-1921, 2017. © 2016 Wiley Periodicals, Inc.

Abstract 1617: RUNX3 inhibits metastasis and angiogenesis in colorectal cancer

Abstract Recent studies proved that an inactivation of RUNX3 (runt-related transcription factor-3) expression is highly associated with lymph node metastasis and poor prognosis in various cancer types. However, the mechanism of RUNX3-mediated suppression of tumor metastasis remains unclear. Herein, we aimed to clarify the effect of RUNX3 on metastasis and angiogenesis in colorectal cancer (CRC). First, we found that the reduction of expression of RUNX3 in CRC tissues when compared with tumor adjacent normal colon tissues, as indicated by reduced RUNX3 staining, was significantly correlated with TNM stage. Second, we demonstrated that RUNX3 overexpression inhibited CRC cell migration and invasion resulting from the elevated upregulation of matrix metalloproteinase-2 and -9 (MMP-2 and MMP-9) expression. In contrast, the knockdown of RUNX3 reduced the inhibition of migration and invasion of CRC cells. Last, Vascular endothelial growth factor(VEGF) is an inducer of angiogenesis and lymphangiogenesis. We found that restoration of RUNX3 decreased vascular endothelial growth factor (VEGF) secretion and suppressed endothelial cell growth and tube formation in CRC cells. Taken together, our data demonstrated that RUNX3 may provide insights into the development of RUNX3 for CRC metastasis diagnostics and therapeutics. Citation Format: Bo Ram Kim, Jung Lim Kim, Yoo Jin Na, Seong Hye Park, Sun Il Lee, Sanghee Kang, Sung Yup Joung, Suk Young Lee, Hong-Jun Kim, Dae-Hee Lee, Byung-Wook Min, Sang Cheul Oh. RUNX3 inhibits metastasis and angiogenesis in colorectal cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1617.

Threonine 209 phosphorylation on RUNX3 by Pak1 is a molecular switch for its dualistic functions.

P21 Activated Kinase 1 (Pak1), an oncogenic serine/threonine kinase, is known to have a significant role in the regulation of cytoskeleton and cellular morphology. Runx3 was initially known for its role in tumor suppressor function, but recent studies have reported the oncogenic role of Runx3 in various cancers. However, the mechanism that controls the paradoxical functions of Runx3 still remains unclear. In this study, we show that Runx3 is a physiologically interacting substrate of Pak1. We identified the site of phosphorylation in Runx3 as Threonine 209 by mass spectrometry analysis and site-directed mutagenesis, and further confirmed the same with a site-specific antibody. Results from our functional studies showed that Threonine 209 phosphorylation in Runx3 alters its subcellular localization by protein mislocalization from the nucleus to the cytoplasm and subsequently converses its biological functions. This was further supported by in vivo tumor xenograft studies in nude mouse models which clearly demonstrated that PANC-28 cells transfected with the Runx3-T209E clone showed high tumorigenic potential as compared with other clones. Our results from clinical samples also suggest that Threonine 209 phosphorylation by Pak1 could be a potential therapeutic target and of great clinical relevance with implications for Runx3 inactivation in cancer cells where Runx3 is known to be oncogenic. The findings presented in this study provide evidence of Runx3-Threonine 209 phosphorylation as a molecular switch in dictating the tissue-specific dualistic functions of Runx3 for the first time.

The emerging role of RUNX3 in cancer metastasis (Review).

Metastasis remains the major driver of mortality in patients with cancer. The multistep metastatic process starts with the dissemination of tumor cells from a primary site and leading to secondary tumor development in an anatomically distant location. Although significant progress has been made in understanding the molecular characteristics of metastasis, many questions remain regarding the intracellular mechanisms governing transition through the various metastatic stages. The runt-related transcription factor 3 (RUNX3) is a downstream effector of the transforming growth factor-β (TGF-β) signaling pathway, and has critical roles in the regulation of cell death by apoptosis, and in angiogenesis, epithelial-to-mesenchymal transition (EMT), cell migration and invasion. RUNX3 functions as a bona fide initiator of carcinogenesis by linking the Wnt oncogenic and TGF-β tumor suppressive pathways. RUNX3 is frequently inactivated in human cancer cell lines and cancer samples by hemizygous deletion of the Runx3 gene, hypermethylation of the Runx3 promoter, or cytoplasmic sequestration of RUNX3 protein. Inactivation of RUNX3 makes it a putative tumor suppressor in human neoplasia. In the present review, we summarize the proposed roles of RUNX3 in metastasis and, when applicable, highlight the mechanism by which they function.

Targeting of RUNX3 by miR-130a and miR-495 cooperatively increases cell proliferation and tumor angiogenesis in gastric cancer cells.

Mature microRNAs (miRNAs) are 21 to 23 nucleotide noncoding RNA molecules that can downregulate multiple gene expression by mRNA degradation or translational repression. miRNAs are considered to play important roles in cell proliferation, apoptosis, and differentiation during mammalian development. The Runt-related transcription factor 3 (RUNX3) expression and activity are frequently downregulated by various mechanisms in gastric cancer. We have reported that RUNX3 inactivation is crucial for early tumorigenesis. In this study, we investigated the role of miRNAs targeting RUNX3 in early tumorigenesis. miR-130a and miR-495 upregulated under hypoxic conditions that bind to the RUNX3 3'-untranslated region (3'-UTR) were identified in gastric cancer cells by using microarray analysis and bioinformatics programs. Combination of miR-130a and miR-495 inhibited RUNX3 expression at the protein level, but not at the mRNA level. miR-130a and miR-495 significantly inhibited the RUNX3-3'UTR-luciferase activity. Combination of miR-130a and miR-495 significantly decreased apoptosis determined by Annexin V-FITC/propidium iodide staining and flow cytometric analysis, and the expression of Bim in SNU484 gastric cancer cells. In addition, p21 and Bim, RUNX3 target genes, were completely downregulated by the combination of miR-130a and miR-495. Using matrigel plug assay, we found that antagomiRs specific for miR-130a and miR-495 significantly reduced angiogenesis in vivo. In conclusion, targeting miR-130a and miR-495 could be a potential therapeutics to recover RUNX3 expression under hypoxic conditions and in early tumorigenic progression.

How do K-RAS-activated cells evade cellular defense mechanisms?

Lung adenocarcinomas, like other cancers, develop through the accumulation of epigenetic and genetic alterations. Numerous studies have shown that K-RAS mutation is among the most important early events in carcinogenesis of the lung. However, it is also well established that growth-stimulating signals feed back into growth-suppressing pathways, and any imbalance in these signaling networks will cause the cell to exit the cell cycle, thereby preventing uncontrolled cell growth. How, then, do K-RAS-activated cells evade cellular defense mechanisms? To answer this question, it is necessary to identify the molecular event(s) responsible for the development of early dysplastic lesions that are unable to defend against aberrant oncogene activation. Lineage-determining transcriptional regulators govern differentiation status during normal lung development, as well as in lung adenocarcinoma. Among the genes involved in K-RAS-induced lung tumorigenesis, RUNX3 is unique: inactivation of Runx3 in mouse lung induces lung adenoma and abrogates the ARF–p53 pathway. This observation raises the possibility of intimate cross-talk between the differentiation program and oncogene surveillance. In this review, we summarized evidences suggesting that K-RAS-activated cells do not evade cellular defense mechanisms per se; instead, cells with K-RAS mutations are selected only if they occur in cells in which defense mechanism is abrogated.

Inactivation of RUNX3 predicts poor prognosis in esophageal squamous cell carcinoma after Ivor-Lewis esophagectomy.

The inactivation of RUNX3 in various cancers has been reported while the expression of RUNX3 on protein level in esophageal squamous cell carcinoma (ESCC) and its relationship with pathological parameters and prognosis still remained unclear. In this study, we examined the expression of RUNX3 in 158 ESCC samples and 20 normal esophageal mucosa samples by immunohistochemistry and qRT-PCR. The IHC result showed that RUNX3 was detected mainly in the nuclei of basal layer cells in 18 of 20 normal mucosa samples while in 158 ESCC samples, there were 46 with RUNX3 nuclei expression, 37 RUNX3 cytoplasmic expression, and 75 negative expression. The qRT-PCR confirmed the downregulation of RUNX3 mRNA in the RUNX3 protein negative group than in the RUNX3 nuclei and cytoplasmic expression group (P < 0.001), and the methylation-specific PCR showed a low methylation rate in the ESCC tissue samples with RUNX3 protein negative expression (6/40, 15%). The RUNX3 nuclei expression negatively correlated with the lymph node metastasis (P = 0.033) and recurrence status (P = 0.019), and the survival analysis showed that the patients with RUNX3 nuclei expression had a higher 5-year survival rate than the patients with RUNX3 cytoplasmic/negative expression (P = 0.022). The Cox regression analysis showed that the T classification (P = 0.001), lymph node metastasis (P < 0.001), and RUNX3 inactivation (negative/cytoplasmic expression, P = 0.039) were independent risk factor of poor prognosis. In conclusion, we found a frequent inactivation of RUNX3 due to low expression and cytoplasmic dislocalization in ESCC. The inactivation of RUNX3 may be involved in the progression of ESCC, and RUNX3 could be an indicator of prognosis for patients with ESCC after surgery.

RUNX3 is inactivated by promoter hypermethylation in malignant transformation of ovarian endometriosis.

The aim of the present study was to investigate the role of epigenetic inactivation of the runt-related transcription factor 3 gene (RUNX3) in the malignant transformation of ovarian endometriosis. Samples obtained by microdissection and scraping included 30 malignant ovarian endometriotic cyst tissues and 30 corresponding eutopic endometrium tissues from the endometriosis-associated ovarian carcinoma (EAOC) group, 19 benign ovarian endometriotic cyst tissues and 22 corresponding eutopic endometrium tissues from the endometriosis (EM) group and 22 normal eutopic endometrium tissues from the control endometrium (CE) group. RUNX3 methylation status was determined by methylation-specific PCR and bisulfite sequencing, while levels of RUNX3 and ERα protein expression were evaluated using immunohistochemistry. The percentage of RUNX3 methylation and negative RUNX3 protein expression in the malignant ovarian endometriotic cysts from the EAOC group was significantly higher than that in the benign ovarian endometriotic cysts from the EM group. The percentage of RUNX3 methylation and negative RUNX3 protein expression in the eutopic endometrium from the EAOC group was significantly higher than that in the EM and CE groups. An inverse correlation between positive RUNX3 protein expression and methylation was observed and a positive correlation was shown between RUNX3 methylation and ERα protein expression. In the malignant ovarian endometriotic cysts from the EAOC group, there was no significant correlation between methylation frequency of the RUNX3 gene and histological type. However, the percentage of RUNX3 gene methylation was significantly higher in the tissue samples from patients with surgical stage IC EAOC than the percentage in patients with stage IA and IB disease. These results suggest that RUNX3 inactivation by promoter hypermethylation plays a role in the progression of malignant transformation of ovarian EM and is closely related to estrogen metabolism. Negative protein expression and abnormal RUNX3 methylation in the eutopic endometrium could be used as diagnostic markers in patients with ovarian EM who may be at an increased risk of developing EAOC.

Abstract 2960: Identification of Runx3 as a gatekeeper of lung adenocarcinoma

Abstract It is thought that SP-C/CC10 double positive cells, which normally contribute to the renewal of lung epithelial cells, are the origin adenocarcinoma (ADC) of the lung. The present study shows that postnatal disruption of Runx3 in the mouse lung results in dedifferentiation of bronchiolar epithelial cells into SP-C/CC10 double positive cells. The double positive cells differentiate into SP-C single positive cells and adenoma (median survival, longer than 1 year). When Adenovirus-Cre was infected, LSL-K-RasG12D mice induced ADC in prolonged latency (median survival, 220 days) and Runx3f/f/LSL-K-RasG12D mice rapidly induced ADC (median survival, 79 days), indicating a strong tumor suppressor activity of Runx3. When Cre was activated in a limited number of cells through a leaky activation of Cretm/ERT in the absence of tamoxifen, K-RasLSL-G12D/+/Cretm/ERT mice did not induce lung ADC. In contrast, simultaneous inactivation of Runx3 and activation of K-Ras (Runx3f/f/K-RasLSL-G12D/+/Cretm/ERT) induced lung ADC with striking morphological similarities to human lung ADC in all mice (median survival, 48 days after birth). We also found that Runx3 forms a complex with BRD2 (a relative of TAF250) in a K-Ras activity-dependent manner and the complex transiently induces p14ARF and p21. When K-Ras was constitutively activated, the Runx3-BRD2 complex was maintained for long time and the expressions of p14ARF and p21 was continued. Disruption of the Runx3-BRD2 complex abolished expression of these two genes. These results suggest that cells recognize oncogenic K-Ras through a monitoring system composed of Runx3-BRD2 complex and Runx3-inactivation leads to abrogation of the monitoring system as well as dedifferentiation of lung epithelial cells. Citation Format: You-Soub Lee, Ju-Won Jang, Xin-Zi Chi, Yoshiaki Ito, Suk-Chul Bae. Identification of Runx3 as a gatekeeper of lung adenocarcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2960. doi:10.1158/1538-7445.AM2014-2960

Clinical significance and association of RUNX3 hypermethylation frequency with colorectal cancer: a meta-analysis.

BackgroundThe RUNX family, which is composed of RUNX1, RUNX2, and RUNX3, is a sequence-specific transcription factor family and is closely involved in a variety of cellular processes including development, differentiation, participation in the regulation of p53-dependent DNA damage response and/or tumorigenesis. Emerging evidence indicates that RUNX3 is a candidate tumor suppressor in several types of human tumors including colorectal cancer (CRC). However, the correlation of RUNX3 inactivation with CRC remains unclear. In the study reported here, we conducted a systematic review and meta-analysis to quantitatively evaluate the effects of RUNX3 hypermethylation/expression on the incidence of CRC.MethodsA detailed search of the literature was made using Medline® and Web of Science for related research publications written in English. The methodological quality of the studies was also evaluated. The data were extracted and assessed by two reviewers independently. Analyses of the pooled data were performed. Odds ratios (ORs) and hazard ratios were calculated and summarized, respectively.ResultsA final analysis of 1,427 CRC patients from eleven eligible studies was performed. We observed that RUNX3 hypermethylation was significantly higher in CRC than in normal colorectal mucosa. The pooled OR from six studies comprising 289 CRC and 188 normal colorectal mucosa was OR =0.07 (confidence interval [CI] =0.03–0.18, P<0.00001). Aberrant RUNX3 hypermethylation/expression was significantly higher in advanced CRC than in early staged CRC (OR =0.54, CI =0.41–0.71, P<0.0001). Aberrant RUNX3 hypermethylation/expression was also significantly higher in microsatellite instability (MSI)-positive CRC than in MSI-negative CRC (OR =0.44, CI =0.3–0.66, P<0.0001). In addition, CRC patients with RUNX3 hypermethylation or lacking RUNX3 protein expression had a lower survival rate than those without RUNX3 hypermethylation or those who did not express RUNX3 protein.ConclusionThe results of this meta-analysis suggest that RUNX3 hypermethylation is associated with an increased risk of CRC, increased risk of progression of CRC, and a poorer CRC survival rate. RUNX3 hypermethylation, which induces the inactivation of RUNX3 gene, plays an important role in colorectal carcinogenesis, high levels of MSI, as well as CRC progression and development.

Retraction Note: DNA methylation-associated inactivation of TGFβ-related genes, DRM/Gremlin, RUNX3, and HPP1 in human cancers

An Internal Review Committee at UT Southwestern Medical Center found evidence of improper manipulation and replication of figures in this paper. A subsequent review by Dr Gazdar and his staff has independently confirmed the Committee’s findings.