Gene Summary

Gene:DIRAS3; DIRAS family GTPase 3
Aliases: ARHI, NOEY2
Summary:This gene encodes a member of the ras superfamily. This gene is imprinted gene with monoallelic expression of the paternal allele which is associated with growth suppression. The encoded protein acts as a tumor suppressor whose function is abrogated in many ovarian and breast cancers. This protein may also play a role autophagy in certain cancer cells by regulating the autophagosome initiation complex. [provided by RefSeq, Nov 2015]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:GTP-binding protein Di-Ras3
Source:NCBIAccessed: 01 September, 2019


What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 01 September 2019 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.

  • Cell Movement
  • Epigenetics
  • Loss of Heterozygosity
  • Transcription
  • Neoplasm Invasiveness
  • Phosphorylation
  • MicroRNAs
  • Breast Cancer
  • Transfection
  • Hydroxamic Acids
  • CpG Islands
  • Azacitidine
  • DNA Methylation
  • Growth Inhibitors
  • Messenger RNA
  • siRNA
  • Western Blotting
  • Mice, Inbred BALB C
  • Down-Regulation
  • Chromosome 1
  • Cancer Gene Expression Regulation
  • Autophagy
  • Cyclin D1
  • RHOA
  • Promoter Regions
  • Ovarian Cancer
  • Gene Silencing
  • rho GTP-Binding Proteins
  • Cell Proliferation
  • Acetylation
  • Genomic Imprinting
  • Histones
  • Decitabine
  • Apoptosis
  • Signal Transduction
  • Cell Cycle
  • Tumor Suppressor Gene
  • Tumor Suppressor Proteins
Tag cloud generated 01 September, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (2)

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: DIRAS3 (cancer-related)

Qiu J, Li X, He Y, et al.
Distinct subgroup of the Ras family member 3 (DIRAS3) expression impairs metastasis and induces autophagy of gastric cancer cells in mice.
J Cancer Res Clin Oncol. 2018; 144(10):1869-1886 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Distinct subgroup of the Ras family member 3 (DIRAS3), also called Aplasia Ras homolog member I, is a tumor suppressor gene that induces autophagy in several cancer cell lines.
METHODS: This study analyzed DIRAS3, and markers of autophagy (p62, and LC3B-II) in surgically resected GC samples from 420 patients. The promotion of autophagy by DIRAS3 in gastric cancer (GC) cells was explored, which might explain its inhibitory role in gastric cancer cells.
RESULTS: DIRAS3 expression in GC was positively correlated with LC3B-II amount, and negatively with metastasis; DIRAS3 and p62 levels were independent prognostic factors in GC. Overexpression of DIRAS3 in BGC-823 cells induced autophagy, led to decreased proliferation, cell cycle arrest in G0/G1 phase, increased apoptosis, and impaired migration and invasion. While knockdown of DIRAS3 promoted proliferation and migration in MKN-45 cells. Overexpression of DIRAS3 in BGC-823 cells elevated autophagy levels in subcutaneous xenograft and inhibited tumor growth in mice; the hematogenous liver and lung metastasis of cancer cells were also suppressed.
CONCLUSIONS: In conclusion, the results suggest DIRAS3 may play a role in affecting proliferation and metastatic potential of GC cells, which may be associated with its involvement in autophagy regulation.

Zhong LX, Nie JH, Liu J, Lin LZ
Correlation of ARHI upregulation with growth suppression and STAT3 inactivation in resveratrol-treated ovarian cancer cells.
Cancer Biomark. 2018; 21(4):787-795 [PubMed] Related Publications
BACKGROUND: Aplysia ras homology member I/ARHI is known as ovarian cancer suppressor gene and potential inhibitor of signal transducer and activator of transcription 3/STAT3 signaling. Resveratrol suppresses growth and STAT3 activation of ovarian cancer cells, while its influence in ARHI expression remains unknown.
OBJECTIVE: The current study aims to elucidate the status of ARHI expression and its relevance with growth suppression and STAT3 inactivation of resveratrol-treated cells.
METHODS: ARHI expression patterns of three ovarian cancer cell lines (human CAOV-3, OVCAR-3 and rat NUTU-19) without and with 100 μM resveratrol treatment were checked by immunocytochemical staining, Western blotting and RT-PCR. The involvement of ARHI in the growth inhibition and STAT3 inactivation of resveratrol-treated OVCAR-3 cells was investigated by transfection of ARHI-specific siRNA.
RESULTS: ARHI is expressed in low levels in three ovarian cancer cell lines, which is upregulated upon resveratrol treatment accompanied with growth arrest, extensive apoptosis, increased autophagic activity and inactivated STAT3 signaling. Specific siRNA transfection efficiently knocked down ARHI expression in resveratrol-treated CAOV-3 and OVCAR-3 cells and increased the total cell number in limited extents (P> 0.05) in comparison with that of resveratrol-treated ovarian cancer cells without any transfection or transfected with mock oligonucleotides. ARHI knockdown failed to prevent resveratrol-caused STAT3 inactivation and cell crisis.
CONCLUSION: ARHI upregulation is another molecular event caused by resveratrol and one of the elements related with resveratrol's anti-ovarian cancer efficacy. Resveratrol may inactivate STAT3 signaling of ovarian cancer cells in ARHI unrelated pattern(s).

Kivinummi K, Urbanucci A, Leinonen K, et al.
The expression of AURKA is androgen regulated in castration-resistant prostate cancer.
Sci Rep. 2017; 7(1):17978 [PubMed] Free Access to Full Article Related Publications
Although second generation endocrine therapies have significantly improved survival, castration-resistant prostate cancer (CRPC) cells are eventually able to escape available hormonal treatments due to reactivation of androgen receptor (AR) signaling. Identification of novel, non-classical and druggable AR-target genes may provide new approaches to treat CRPC. Our previous analyses suggested that Aurora kinase A (AURKA) is regulated by androgens in prostate cancer cells that express high levels of AR. Here, we provide further evidence that AURKA is significantly overexpressed in AR-positive CRPC samples carrying amplification of AR gene and/or expressing AR in high levels. We also demonstrate androgen-induced AR binding in the intronic region of AURKA. The expression of AURKA is increased upon androgen stimulation in LNCaP-ARhi cells that express high levels of AR. The growth of the cells was also significantly inhibited by an AURKA specific inhibitor, alisertib (MLN8237). Together, these findings suggest that the expression of AURKA is regulated by androgen in prostate cancer cells that highly express AR, emphasizing its potential as a therapeutic target in patients with CRPC.

Nowak EM, Poczęta M, Bieg D, Bednarek I
DNA methyltransferase inhibitors influence on the DIRAS3 and STAT3 expression and in vitro migration of ovarian and breast cancer cells.
Ginekol Pol. 2017; 88(10):543-551 [PubMed] Related Publications
OBJECTIVES: Downregulation of DIRAS3 (DIRAS family, GTP-binding Ras-like 3) is related to ovarian and breast cancer progression. A possible mechanism that silences this gene is the promoter region DNA methylation. The potential reversibility of this epigenetic mechanism makes it more attractive candidate for new mode of cancer treatment. DIRAS3 regulates cell cycle, tumor dormancy and inhibits cancer cell growth and motility, all of which may indirectly depend on interaction with STAT3 (Signal Transducer and Activator of Transcription 3) classified as a potential oncogene. The restoration of DIRAS3 expression could inhibit cell proliferation and invasiveness.
MATERIAL AND METHODS: Human ovarian carcinoma cell line (A2780) and human breast cancer cell line (MCF7) were exposed to two DNA methyltransferase inhibitors (DNMTi): decitabine (5-aza-2'-deoxycytidine) [25 μM and 12.5 μM] and RG108 [150 μM and 100 μM]. In vitro migration changes of cancer cells were examined with wound healing assay. After 7 days of DNMTi treatment cells were harvested and DNA and RNA was isolated. The methylation status of the promoter sequences of DIRAS3 and STAT3 genes was determined using methylation specific PCR (MS-PCR). Level of target genes' expression was quantified using quantitative reverse transcription PCR (QRT-PCR).
RESULTS AND CONCLUSIONS: The in vitro wound healing assay showed changes in the migration rate of both adherent cell lines after DNMTi treatment compared to the untreated cells. Relative balance between methylated and unmethylated variants of DIRAS3 after MS-PCR was shifted towards unmethylated version after DNMTi treatment in A2780 cells. Statistically significant dose dependent effect of decitabine and RG108 on DIRAS3 expression in A2780 cells was observed.

Ferraresi A, Phadngam S, Morani F, et al.
Resveratrol inhibits IL-6-induced ovarian cancer cell migration through epigenetic up-regulation of autophagy.
Mol Carcinog. 2017; 56(3):1164-1181 [PubMed] Related Publications
Interleukin-6 (IL-6), a pro-inflammatory cytokine released by cancer-associated fibroblasts, has been linked to the invasive and metastatic behavior of ovarian cancer cells. Resveratrol is a naturally occurring polyphenol with the potential to inhibit cancer cell migration. Here we show that Resveratrol and IL-6 affect in an opposite manner the expression of RNA messengers and of microRNAs involved in cell locomotion and extracellular matrix remodeling associated with the invasive properties of ovarian cancer cells. Among the several potential candidates responsible for the anti-invasive effect promoted by Resveratrol, here we focused our attention on ARH-I (DIRAS3), that encodes a Ras homolog GTPase of 26-kDa. This protein is known to inhibit cell motility, and it has been shown to regulate autophagy by interacting with BECLIN 1. IL-6 down-regulated the expression of ARH-I and inhibited the formation of LC3-positive autophagic vacuoles, while promoting cell migration. On opposite, Resveratrol could counteract the IL-6 induction of cell migration in ovarian cancer cells through induction of autophagy in the cells at the migration front, which was paralleled by up-regulation of ARH-I and down-regulation of STAT3 expression. Spautin 1-mediated disruption of BECLIN 1-dependent autophagy abrogated the effects of Resveratrol, while promoting cell migration. The present data indicate that Resveratrol elicits its anti-tumor effect through epigenetic mechanisms and support its inclusion in the chemotherapy regimen for highly aggressive ovarian cancers. © 2016 Wiley Periodicals, Inc.

Lapinska K, Housman G, Byler S, et al.
The Effects of Histone Deacetylase Inhibitor and Calpain Inhibitor Combination Therapies on Ovarian Cancer Cells.
Anticancer Res. 2016; 36(11):5731-5742 [PubMed] Related Publications
BACKGROUND: Ovarian cancer is difficult to treat due to absence of selective drugs and tendency of platinum drugs to promote resistance. Combination therapy using epigenetic drugs is predicted to be a beneficial alternative.
MATERIALS AND METHODS: This study investigated the effects of combination therapies using two structurally different histone deacetylase (HDAC) inhibitors (HDACi), sodium butyrate and suberanilohydroxamic acid (SAHA), with the calpain inhibitor calpeptin on two characteristically different ovarian cancer cell lines, CAOV-3 and SKOV-3.
RESULTS: Suboptimal doses of HDACi and calpeptin produced several effects. Growth inhibition was enhanced and the epigenetically silenced tumor suppressor genes ARHI, p21 and RARβ2 were re-expressed. Methylation of specific CpG residues in ARHI were reduced. Cell-cycle progression was inhibited and apoptosis, as well as autophagy, were induced. The phosphorylation of ERK and Akt were differentially effected by these inhibitors.
CONCLUSION: The re-expression of tumor suppressors may sensitize ovarian cancer cells, which then undergo apoptosis and autophagy for cell death.

Ye K, Wang S, Wang J, et al.
Zebularine enhances apoptosis of human osteosarcoma cells by suppressing methylation of ARHI.
Cancer Sci. 2016; 107(12):1851-1857 [PubMed] Free Access to Full Article Related Publications
ARHI is an imprinted tumor suppressor gene and its methylation suppresses ARHI transcription levels to cause the development and progression of malignant tumors. Zebularine exerts a demethylation function for tumor suppressor genes. Our study aims to investigate the effect and mechanism of action of zebularine on the epigenetic modification of the ARHI gene, and whether this effect may modulate the viability and apoptosis of human osteosarcoma cells. We found that zebularine inhibited the viability and promoted apoptosis in osteosarcoma cells. Zebularine potentiated the expression of ARHI at both the protein and mRNA level. This was related to the downregulation of methylation of ARHI caused by zebularine. Zebularine suppressed the interaction of DNA methyltransferase 1 (DNMT1) with histone methyltransferase G9a, but had no effect on G9a alone. Knockdown of DNMT1 or G9a can induce a reduction of ARHI methylation. Therefore, we inferred that zebularine was likely to directly repress DNMT1 alone, but G9a was necessary to regulate the function of DNMT1 on ARHI methylation. Moreover, knockdown of ARHI rescued cell viability and apoptosis under the zebularine-treated condition. We showed that zebularine inhibited viability and promoted apoptosis by disturbing the interaction between DNMT1 and G9a, thereby resulting in lower ARHI methylation and elevated ARHI expression in osteosarcoma cells.

Bergom C, Hauser AD, Rymaszewski A, et al.
The Tumor-suppressive Small GTPase DiRas1 Binds the Noncanonical Guanine Nucleotide Exchange Factor SmgGDS and Antagonizes SmgGDS Interactions with Oncogenic Small GTPases.
J Biol Chem. 2016; 291(12):6534-45 [PubMed] Free Access to Full Article Related Publications
The small GTPase DiRas1 has tumor-suppressive activities, unlike the oncogenic properties more common to small GTPases such as K-Ras and RhoA. Although DiRas1 has been found to be a tumor suppressor in gliomas and esophageal squamous cell carcinomas, the mechanisms by which it inhibits malignant phenotypes have not been fully determined. In this study, we demonstrate that DiRas1 binds to SmgGDS, a protein that promotes the activation of several oncogenic GTPases. In silico docking studies predict that DiRas1 binds to SmgGDS in a manner similar to other small GTPases. SmgGDS is a guanine nucleotide exchange factor for RhoA, but we report here that SmgGDS does not mediate GDP/GTP exchange on DiRas1. Intriguingly, DiRas1 acts similarly to a dominant-negative small GTPase, binding to SmgGDS and inhibiting SmgGDS binding to other small GTPases, including K-Ras4B, RhoA, and Rap1A. DiRas1 is expressed in normal breast tissue, but its expression is decreased in most breast cancers, similar to its family member DiRas3 (ARHI). DiRas1 inhibits RhoA- and SmgGDS-mediated NF-κB transcriptional activity in HEK293T cells. We also report that DiRas1 suppresses basal NF-κB activation in breast cancer and glioblastoma cell lines. Taken together, our data support a model in which DiRas1 expression inhibits malignant features of cancers in part by nonproductively binding to SmgGDS and inhibiting the binding of other small GTPases to SmgGDS.

Washington MN, Suh G, Orozco AF, et al.
ARHI (DIRAS3)-mediated autophagy-associated cell death enhances chemosensitivity to cisplatin in ovarian cancer cell lines and xenografts.
Cell Death Dis. 2015; 6:e1836 [PubMed] Free Access to Full Article Related Publications
Autophagy can sustain or kill tumor cells depending upon the context. The mechanism of autophagy-associated cell death has not been well elucidated and autophagy has enhanced or inhibited sensitivity of cancer cells to cytotoxic chemotherapy in different models. ARHI (DIRAS3), an imprinted tumor suppressor gene, is downregulated in 60% of ovarian cancers. In cell culture, re-expression of ARHI induces autophagy and ovarian cancer cell death within 72 h. In xenografts, re-expression of ARHI arrests cell growth and induces autophagy, but does not kill engrafted cancer cells. When ARHI levels are reduced after 6 weeks, dormancy is broken and xenografts grow promptly. In this study, ARHI-induced ovarian cancer cell death in culture has been found to depend upon autophagy and has been linked to G1 cell-cycle arrest, enhanced reactive oxygen species (ROS) activity, RIP1/RIP3 activation and necrosis. Re-expression of ARHI enhanced the cytotoxic effect of cisplatin in cell culture, increasing caspase-3 activation and PARP cleavage by inhibiting ERK and HER2 activity and downregulating XIAP and Bcl-2. In xenografts, treatment with cisplatin significantly slowed the outgrowth of dormant autophagic cells after reduction of ARHI, but the addition of chloroquine did not further inhibit xenograft outgrowth. Taken together, we have found that autophagy-associated cancer cell death and autophagy-enhanced sensitivity to cisplatin depend upon different mechanisms and that dormant, autophagic cancer cells are still vulnerable to cisplatin-based chemotherapy.

Ye K, Wang S, Yang Y, et al.
Aplasia Ras homologue member Ⅰ overexpression inhibits tumor growth and induces apoptosis through inhibition of PI3K/Akt survival pathways in human osteosarcoma MG-63 cells in culture.
Int J Mol Med. 2015; 36(3):776-82 [PubMed] Related Publications
Aplasia Ras homologue member Ⅰ (ARHI), an imprinted tumor-suppressor gene, is downregulated in various types of cancer. However, the expression, function and specific mechanisms of ARHI in human osteosarcoma (OS) cells remain unclear. The aim of the present study was to assess the effect of ARHI on OS cell proliferation and apoptosis and its associated mechanism. In the study, ARHI mRNA and protein levels were markedly downregulated in OS cells compared with the human osteoblast precursor cell line hFOB1.19. By generating stable transfectants, ARHI was overexpressed in OS cells that had low levels of ARHI. Overexpression of ARHI inhibited cell viability and proliferation and induced apoptosis. However, caspase‑3 activity was not changed by ARHI overexpression. In addition, phosphorylated Akt protein expression decreased in the ARHI overexpression group compared to that in the control vector group. The knockdown of ARHI also resulted in the promotion of cell proliferation and the attenuation of apoptosis in MG‑63 cells. Additionally, ARHI silencing increased the level of p‑Akt. The present results indicate that ARHI inhibits OS cell proliferation and may have a key role in the development of OS.

Barrow TM, Barault L, Ellsworth RE, et al.
Aberrant methylation of imprinted genes is associated with negative hormone receptor status in invasive breast cancer.
Int J Cancer. 2015; 137(3):537-47 [PubMed] Free Access to Full Article Related Publications
Epigenetic regulation of imprinted genes enables monoallelic expression according to parental origin, and its disruption is implicated in many cancers and developmental disorders. The expression of hormone receptors is significant in breast cancer because they are indicators of cancer cell growth rate and determine response to endocrine therapies. We investigated the frequency of aberrant events and variation in DNA methylation at nine imprinted sites in invasive breast cancer and examined the association with estrogen and progesterone receptor status. Breast tissue and blood from patients with invasive breast cancer (n = 38) and benign breast disease (n = 30) were compared with those from healthy individuals (n = 36), matched with the cancer patients by age at diagnosis, ethnicity, body mass index, menopausal status and familial history of cancer. DNA methylation and allele-specific expression were analyzed by pyrosequencing. Tumor-specific methylation changes at IGF2 DMR2 were observed in 59% of cancer patients, IGF2 DMR0 in 38%, DIRAS3 DMR in 36%, GRB10 ICR in 23%, PEG3 DMR in 21%, MEST ICR in 19%, H19 ICR in 18%, KvDMR in 8% and SNRPN/SNURF ICR in 4%. Variation in methylation was significantly greater in breast tissue from cancer patients compared with that in healthy individuals and benign breast disease. Aberrant methylation of three or more sites was significantly associated with negative estrogen-alpha (Fisher's exact test, p = 0.02) and progesterone-A (p = 0.02) receptor status. Aberrant events and increased variation in imprinted gene DNA methylation, therefore, seem to be frequent in invasive breast cancer and are associated with negative estrogen and progesterone receptor status, without loss of monoallelic expression.

Yu J, Kong CZ, Zhang Z, et al.
Aplasia Ras homolog member I expression induces apoptosis in renal cancer cells via the β-catenin signaling pathway.
Mol Med Rep. 2015; 11(1):475-81 [PubMed] Related Publications
In numerous types of cancer, the Ras-associated tumor suppressor gene aplasia Ras homolog member I (ARHI), is downregulated. However, the function of ARHI in renal cancer remains to be elucidated. The present study investigated whether the suppressor gene ARHI influenced the growth of renal cancer cell lines and aimed to elucidate its mechanism of action, using the techniques of cell biology and molecular pathology. To the best of our knowledge, the present study was the first to determine the effects of ARHI on human renal cancer cells in vivo and in vitro. It was demonstrated that ARHI exhibited a tumor suppressor function in OS-RC-2 cells and acted via the β-catenin signaling pathway. It was additionally confirmed that the levels of ARHI messenger RNA and protein in renal cancer tissues were lower than those in matched normal tissues. These results provided a novel insight into the possible therapeutic applications of ARHI in renal cancer.

Zhang S, Lu Z, Unruh AK, et al.
Clinically relevant microRNAs in ovarian cancer.
Mol Cancer Res. 2015; 13(3):393-401 [PubMed] Free Access to Full Article Related Publications
microRNAs (miRNAs/miRs) belong to a class of small noncoding RNAs that can negatively regulate messenger RNA (mRNA) expression of target genes. miRNAs are involved in multiple aspects of ovarian cancer cell dysfunction and the phenotype of ovarian cancer cells can be modified by targeting miRNA expression. miRNA profiling has detected a number of candidate miRNAs with the potential to regulate many important biologic functions in ovarian cancer, but their role still needs to be clarified, given the remarkable heterogeneity among ovarian cancers and the context-dependent role of miRNAs. This review summarizes the data collected from The Cancer Genome Atlas (TCGA) and several other genome-wide projects to identify dysregulated miRNAs in ovarian cancers. Copy number variations (CNVs), epigenetic alterations, and oncogenic mutations are also discussed that affect miRNA levels in ovarian disease. Emphasis is given to the role of particular miRNAs in altering expression of genes in human ovarian cancers with the potential to provide diagnostic, prognostic, and therapeutic targets. Particular attention has been given to TP53, BRCA1/2, CA125 (MUC16), HE4 (WFDC2), and imprinted genes such as ARHI (DIRAS3). A better understanding of the abnormalities in miRNA expression and downstream transcriptional and biologic consequences will provide leads for more effective biomarkers and translational approaches in the management of ovarian cancer.

Li L, Gao P, Li Y, et al.
JMJD2A-dependent silencing of Sp1 in advanced breast cancer promotes metastasis by downregulation of DIRAS3.
Breast Cancer Res Treat. 2014; 147(3):487-500 [PubMed] Related Publications
Specificity protein 1(Sp1) is a ubiquitous transcription factor and is highly expressed in breast cancer. However, its expression pattern and role in breast cancer progression remain unclear. The purpose of this study is to examine the expression pattern of Sp1 and determine its role in breast cancer progression. Immunohistochemistry (IHC) was performed on breast cancer tissues to reveal the expression pattern of Sp1. Spearman rank correlation was used for clinical statistics. Gene and protein expressions were monitored by IHC analysis, quantitative polymerase chain reaction, and Western blot. Wound-healing and Transwell assays were conducted to assess the role of Sp1 in breast cancer. Co-immunoprecipitation, deletion mutagenesis, chromatin immunoprecipitation, and dual luciferase reporter gene assays were used for investigation of the regulatory network. Sp1 expression was downregulated in late stage breast cancer and in highly invasive breast cancer cell lines. Expression of Sp1 was negatively correlated with TNM staging (P = 0.002) and metastasis status (P = 0.023). Overexpression of Sp1 inhibited breast cancer cell migratory and invasive abilities, whereas knockdown of GTP-binding RAS-like 3 (DIRAS3, also known as ARHI, NOEY2) attenuated the inhibitory effects. Moreover, re-expression of DIRAS3 abolished Sp1 knockdown-mediated cell migration and invasion. Jumonji domain containing 2A (JMJD2A) inhibited Sp1 autoregulation and explains Sp1 expression pattern in breast cancer. Sp1 negatively regulated breast cancer metastasis by transcriptional activation of DIRAS3. Inhibition of Sp1 autoregulation by JMJD2A contributed to Sp1 expression pattern in breast cancer. Our findings provided evidence that targeted therapy against Sp1 might be useful in early stage breast cancer. However, in late stages, development of Sp1 activator may be more promising for breast cancer treatments.

Fu Y, Chen J, Pang B, et al.
EZH2-induced H3K27me3 is associated with epigenetic repression of the ARHI tumor-suppressor gene in ovarian cancer.
Cell Biochem Biophys. 2015; 71(1):105-12 [PubMed] Related Publications
Epithelial ovarian cancer (EOC) is the second leading cause of death from gynecological malignancies worldwide. Enhancer of zeste homology 2 (EZH2), participating in gene expression silencing by trimethylating histone 3 lysine 27 (H3K27me3), is often up-regulated in EOC. ARHI, an imprinted tumor-suppressor gene, is markedly down-regulated or even undetectable in the majority of EOC. To explore the correlation between EZH2 and ARHI expression in EOC as well as the possible mechanism of EZH2-ARH1 interaction. We used immunohistochemical staining to evaluate the expression of EZH2 and ARHI in EOC and normal ovarian tissue specimens; western blotting, shRNA, and chromatin immunoprecipitation were used to study the expression correlation of EZH2 and ARHI in EOC and normal ovarian epithelial cells and to further explore the mechanism of EZH2 regulation of ARHI expression. Cell viability assay was used to evaluate the influence of these two genes on cell survival. (1) The expression of EZH2 inversely correlated with ARHI expression levels and predicted shorter overall survival in EOC patients; (2) EZH2 promoted repression of ARHI by catalyzing trimethylation on H3K27; (3) ARHI was synergistically silenced by DNA methylation and histone modification; and (4) DZNep, an inhibitor of EZH2, significantly reduced survival rate of EOC cells by restoring ARHI expression. EZH2-″induced H3K27me3 is associated with epigenetic repression of the ARHI tumor-suppressor gene in EOC. Suppression of EZH2 by DZNep, as a way of restoring the expression of ARHI, could be a potential treatment modality to EOC.

Li LL, Xue AM, Li BX, et al.
JMJD2A contributes to breast cancer progression through transcriptional repression of the tumor suppressor ARHI.
Breast Cancer Res. 2014; 16(3):R56 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION: Breast cancer is a worldwide health problem and the leading cause of cancer death among females. We previously identified Jumonji domain containing 2A (JMJD2A) as a critical mediator of breast cancer proliferation, migration and invasion. We now report that JMJD2A could promote breast cancer progression through transcriptional repression of the tumor suppressor aplasia Ras homolog member I (ARHI).
METHODS: Immunohistochemistry was performed to examine protein expressions in 155 cases of breast cancer and 30 non-neoplastic tissues. Spearman correlation analysis was used to analyze the correlation between JMJD2A expression and clinical parameters as well as several tumor regulators in 155 cases of breast cancer. Gene and protein expressions were monitored by quantitative polymerase chain reaction (qPCR) and Western blot. Results from knockdown of JMJD2A, overexpression of JMJD2A, Co-immunoprecipitation (Co-IP) assay, dual luciferase reporter gene assay and chromatin immunoprecipitation (ChIP) elucidated molecular mechanisms of JMJD2A action in breast cancer progression. Furthermore, the effects of ARHI overexpression on JMJD2A-mediated tumor progression were investigated in vitro and in vivo. For in vitro experiments, cell proliferation, wound-healing, migration and invasion were monitored by cell counting, scratch and Boyden Chamber assays. For in vivo experiments, control cells and cells stably expressing JMJD2A alone or together with ARHI were inoculated into mammary fat pads of mice. Tumor volume, tumor weight and metastatic nodules were measured by caliper, electronic balance and nodule counting, respectively.
RESULTS: JMJD2A was highly expressed in human breast cancers and positively correlated with tumor progression. Knockdown of JMJD2A increased ARHI expression whereas overexpression of JMJD2A decreased ARHI expression at both protein and mRNA levels. Furthermore, E2Fs and histone deacetylases were involved in the transcriptional repression of ARHI expression by JMJD2A. And the aggressive behavior of JMJD2A in breast cancers could be reversed by re-expression of ARHI in vitro and in vivo.
CONCLUSION: We demonstrated a cancer-promoting effect of JMJD2A and defined a novel molecular pathway contributing to JMJD2A-mediated breast cancer progression.

Lu Z, Baquero MT, Yang H, et al.
DIRAS3 regulates the autophagosome initiation complex in dormant ovarian cancer cells.
Autophagy. 2014; 10(6):1071-92 [PubMed] Free Access to Full Article Related Publications
DIRAS3 is an imprinted tumor suppressor gene that is downregulated in 60% of human ovarian cancers. Re-expression of DIRAS3 at physiological levels inhibits proliferation, decreases motility, induces autophagy, and regulates tumor dormancy. Functional inhibition of autophagy with choroquine in dormant xenografts that express DIRAS3 significantly delays tumor regrowth after DIRAS3 levels are reduced, suggesting that autophagy sustains dormant ovarian cancer cells. This study documents a newly discovered role for DIRAS3 in forming the autophagosome initiation complex (AIC) that contains BECN1, PIK3C3, PIK3R4, ATG14, and DIRAS3. Participation of BECN1 in the AIC is inhibited by binding of BECN1 homodimers to BCL2. DIRAS3 binds BECN1, disrupting BECN1 homodimers and displacing BCL2. Binding of DIRAS3 to BECN1 increases the association of BECN1 with PIK3C3 and ATG14, facilitating AIC activation. Amino acid starvation of cells induces DIRAS3 expression, reduces BECN1-BCL2 interaction and promotes autophagy, whereas DIRAS3 depletion blocks amino acid starvation-induced autophagy. In primary ovarian cancers, punctate expression of DIRAS3, BECN1, and the autophagic biomarker MAP1LC3 are highly correlated (P<0.0001), underlining the clinical relevance of these mechanistic studies. Punctate expression of DIRAS3 and MAP1LC3 was detected in only 21-23% of primary ovarian cancers but in 81-84% of tumor nodules found on the peritoneal surface at second-look operations following primary chemotherapy. This reflects a 4-fold increase (P<0.0001) in autophagy between primary disease and post-treatment recurrence. We suggest that DIRAS3 not only regulates the AIC, but induces autophagy in dormant, nutrient-deprived ovarian cancer cells that remain after conventional chemotherapy, facilitating their survival.

Lu Z, Yang H, Sutton MN, et al.
ARHI (DIRAS3) induces autophagy in ovarian cancer cells by downregulating the epidermal growth factor receptor, inhibiting PI3K and Ras/MAP signaling and activating the FOXo3a-mediated induction of Rab7.
Cell Death Differ. 2014; 21(8):1275-89 [PubMed] Free Access to Full Article Related Publications
The process of autophagy has been described in detail at the molecular level in normal cells, but less is known of its regulation in cancer cells. Aplasia Ras homolog member I (ARHI; DIRAS3) is an imprinted tumor suppressor gene that is downregulated in multiple malignancies including ovarian cancer. Re-expression of ARHI slows proliferation, inhibits motility, induces autophagy and produces tumor dormancy. Our previous studies have implicated autophagy in the survival of dormant ovarian cancer cells and have shown that ARHI is required for autophagy induced by starvation or rapamycin treatment. Re-expression of ARHI in ovarian cancer cells blocks signaling through the PI3K and Ras/MAP pathways, which, in turn, downregulates mTOR and initiates autophagy. Here we show that ARHI is required for autophagy-meditated cancer cell arrest and ARHI inhibits signaling through PI3K/AKT and Ras/MAP by enhancing internalization and degradation of the epidermal growth factor receptor. ARHI-mediated downregulation of PI3K/AKT and Ras/ERK signaling also decreases phosphorylation of FOXo3a, which sequesters this transcription factor in the nucleus. Nuclear retention of FOXo3a induces ATG4 and MAP-LC3-I, required for maturation of autophagosomes, and also increases the expression of Rab7, required for fusion of autophagosomes with lysosomes. Following the knockdown of FOXo3a or Rab7, autophagolysosome formation was observed but was markedly inhibited, resulting in numerous enlarged autophagosomes. ARHI expression correlates with LC3 expression and FOXo3a nuclear localization in surgical specimens of ovarian cancer. Thus, ARHI contributes to the induction of autophagy through multiple mechanisms in ovarian cancer cells.

Zuo X, Qin Y, Zhang X, et al.
Breast cancer cells are arrested at different phases of the cell cycle following the re-expression of ARHI.
Oncol Rep. 2014; 31(5):2358-64 [PubMed] Related Publications
ARHI is a maternally imprinted tumor suppressor gene that is expressed in normal breast epithelial cells but not in most breast cancer cells. Aberrant methylation and hypernomic histone deacetylation have been implicated in the silencing of ARHI. To investigate the mechanism of ARHI induction, MDA-MB-231 breast cancer cells were either transfected with the eukaryotic expression vector, pcDNA3.1(+)-ARHI, or were simultaneously treated with a histone deacetylase inhibitor, [trichostatin A, (TSA)] and the methyltransferase inhibitor, 5-aza-2'-deoxycytidine (DAC). The latter treatment group also included the targeting of ARHI by small interfering RNA (siRNA) to further examine interactions between ARHI and the drugs applied. Levels of ARHI were detected by western blotting, MTT assays were used to evaluate cell proliferation, and both cell cycle progression and apoptosis were detected using flow cytometry. Both the transfection of pcDNA3.1(+)‑ARHI and the application of TSA+DAC induced the expression of ARHI. Furthermore, reduced cell proliferation, cell cycle arrest and enhanced apoptosis were observed for both groups compared to controls. However, a G1/S cell cycle arrest was observed for the pcDNA3.1(+)-ARHI group, while a G2 cell cycle arrest was observed for the TSA+DAC group. The latter effect was reversed with the introduction of ARHI-targeted siRNA in combination with TSA+DAC treatment. To further clarify these observations, expression levels of several key cell cycle regulators were analyzed by western blotting. The pcDNA3.1(+)-ARHI group exhibited higher expression levels of p53, p21 and p27, and lower levels of cyclin D1, CDK4 and CDK6 when compared to the control group (P<0.05). For the TSA+DAC group, higher levels of p53, p21, cyclin B1 and Chk1 were detected, concomitant with lower levels of CDK1, when compared to the control group. Taken together, these results suggest that ARHI acts as a tumor suppressor gene in MDA-MB-231 cells and, although TSA+DAC can block the cells at different cell cycle phage, the antitumor effect is ARHI-dependent.

Li J, Cui G, Sun L, et al.
ARHI overexpression induces epithelial ovarian cancer cell apoptosis and excessive autophagy.
Int J Gynecol Cancer. 2014; 24(3):437-43 [PubMed] Related Publications
OBJECTIVE: ARHI is a maternally imprinted tumor suppressor gene that is responsible for initiating programmed cell death and inhibiting cancer cell growth. However, the influence of ARHI on epithelial ovarian cancer cell death and the underlying mechanisms behind how ARHI regulates cancer cells still require further studies.
METHODS: Epithelial ovarian cancer cells TOV112D and ES-2 were used in this in vitro study. Cell proliferation, apoptosis, and autophagy activities were compared in TOV112D and ES-2 cells transfected with ARHI vectors or control vectors. Bcl-2 siRNA was transfected into TOV112D cells to investigate the roles of Bcl-2 played in regulating apoptosis and autophagy.
RESULTS: ARHI expression was reduced in TOV112D and ES-2 cells compared with normal epithelial ovarian cells (NOE095 and HOSEpiC). Overexpressed ARHI inhibited cancer cell proliferation, whereas induced forced cell apoptosis and excessive formation of autophagosomes inhibited promoted cell death. Furthermore, we found that Bcl-2 expression moderately declined in response to ARHI overexpressing in ES-2 and TOV112D cells; meanwhile, more apoptotic cells and higher LC3 level presented after silence of Bcl-2 in TOV112D cells. Reduced Bcl-2-Beclin 1 complex were observed in ARHI overexpressing cells. Moreover, modulation of ARHI to Bcl-2 expression could be ascribed partially to the activation of PI3k/AKT pathway. The addition of LY294002 enabled to suppress Bcl-2 expression and cell proliferation.
CONCLUSIONS: The silence of ARHI expression in vitro seems to accelerate the malignant transformation of healthy ovarian cells by restraining apoptosis and autophagy. The overexpressed ARHI in TOV112D cancer cells suppresses the activation of PI3K/AKT and reduces the expression of Bcl-2, leading to enhanced cell apoptosis and autophagic cancer cell death.

Chen J, Shi S, Yang W, Chen C
Over-expression of ARHI decreases tumor growth, migration, and invasion in human glioma.
Med Oncol. 2014; 31(3):846 [PubMed] Related Publications
This study was conducted to evaluate the role of tumor suppressor gene ras homologue member I (ARHI) in human glioma tumors. We examined expression of ARHI in human glioma tumors and normal brain tissue and also in 4 different glioma cell lines. Furthermore, the effects of ARHI over-expression produced by cellular transfection on the growth of human glioma U251 cells cultured in vitro were also studied. Expression of ARHI was evaluated in samples of glioma tumors obtained from 59 patients who underwent surgery at the Department of Neurosurgery, Fujian Medical University Union Hospital, Fuzhou, China. Ten samples of normal brain tissue were used as controls. Additionally, in vitro studies were conducted in which a recombinant vector carrying ARHI cDNA was constructed and transfected into U251 glioma cells with reduced expression of ARHI. Following transfection, the MTT assay, flow cytometry, TUNEL procedure, Transwell assay, and wound-healing test were employed to evaluate the biological functions of ARHI in U251 glioma cells in vitro. Analyses of mRNA and protein expression revealed that ARHI was significantly down-regulated in glioma tissues as well as in 4 malignant glioma cell lines. Over-expression of ARHI resulted in suppression of glioma cell proliferation, arrest of cell cycle progression, reduction in cell migration and invasion, and promotion of cell apoptosis. Collectively, our data highlight the importance of ARHI in glioma progression and provide the first biological basis for ARHI as a novel candidate target for gene therapy of glioma.

Lyu T, Jia N, Wang J, et al.
Expression and epigenetic regulation of angiogenesis-related factors during dormancy and recurrent growth of ovarian carcinoma.
Epigenetics. 2013; 8(12):1330-46 [PubMed] Free Access to Full Article Related Publications
The initiation of angiogenesis can mark the transition from tumor dormancy to active growth and recurrence. Mechanisms that regulate recurrence in human cancers are poorly understood, in part because of the absence of relevant models. The induction of ARHI (DIRAS3) induces dormancy and autophagy in human ovarian cancer xenografts but produces autophagic cell death in culture. The addition of VEGF to cultures maintains the viability of dormant autophagic cancer cells, thereby permitting active growth when ARHI is downregulated, which mimics the "recurrence" of growth in xenografts. Two inducible ovarian cancer cell lines, SKOv3-ARHI and Hey-ARHI, were used. The expression level of angiogenesis factors was evaluated by real-time PCR, immunohistochemistry, immunocytochemistry and western blot; their epigenetic regulation was measured by bisulfite sequencing and chromatin immunoprecipitation. Six of the 15 angiogenesis factors were upregulated in dormant cancer cells (tissue inhibitor of metalloproteinases-3, TIMP3; thrombospondin-1, TSP1; angiopoietin-1; angiopoietin-2; angiopoietin-4; E-cadherin, CDH1). We found that TIMP3 and CDH1 expression was regulated epigenetically and was related inversely to the DNA methylation of their promoters in cell cultures and in xenografts. Increased H3K9 acetylation was associated with higher TIMP3 expression in dormant SKOv3-ARHI cells, while decreased H3K27me3 resulted in the upregulation of TIMP3 in dormant Hey-ARHI cells. Elevated CDH1 expression during dormancy was associated with an increase in both H3K4me3 and H3K9Ac in two cell lines. CpG demethylating agents and/or histone deacetylase inhibitors inhibited the re-growth of dormant cancer cells, which was associated with the re-expression of anti-angiogenic genes. The expression of the anti-angiogenic genes TIMP3 and CDH1 is elevated during dormancy and is reduced during the transition to active growth by changes in DNA methylation and histone modification.

Niemczyk M, Ito Y, Huddleston J, et al.
Imprinted chromatin around DIRAS3 regulates alternative splicing of GNG12-AS1, a long noncoding RNA.
Am J Hum Genet. 2013; 93(2):224-35 [PubMed] Free Access to Full Article Related Publications
Imprinted gene clusters are regulated by long noncoding RNAs (lncRNAs), CCCTC binding factor (CTCF)-mediated boundaries, and DNA methylation. DIRAS3 (also known as ARH1 or NOEY1) is an imprinted gene encoding a protein belonging to the RAS superfamily of GTPases and is located within an intron of a lncRNA called GNG12-AS1. In this study, we investigated whether GNG12-AS1 is imprinted and coregulated with DIRAS3. We report that GNG12-AS1 is coexpressed with DIRAS3 in several tissues and coordinately downregulated with DIRAS3 in breast cancers. GNG12-AS1 has several splice variants, all of which initiate from a single transcription start site. In placenta tissue and normal cell lines, GNG12-AS1 is biallelically expressed but some isoforms are allele-specifically spliced. Cohesin plays a role in allele-specific splicing of GNG12-AS1. In breast cancer cell lines with loss of DIRAS3 imprinting, DIRAS3 and GNG12-AS1 are silenced in cis and the remaining GNG12-AS1 transcripts are predominantly monoallelic. The GNG12-AS1 locus, which includes DIRAS3, provides an example of imprinted cotranscriptional splicing and a potential model system for studying the long-range effects of CTCF-cohesin binding on splicing and transcriptional interference.

Li Y, Liu M, Zhang Y, et al.
Effects of ARHI on breast cancer cell biological behavior regulated by microRNA-221.
Tumour Biol. 2013; 34(6):3545-54 [PubMed] Related Publications
The aplysia ras homolog member I (ARHI) is a tumor suppressor gene and is downregulated in various cancers. The downregulation of ARHI was regulated by miR-221 in prostate cancer cell lines. However, it has not been reported whether ARHI is regulated by miR-221 in breast cancer. Here, we reported that the ARHI protein level was downregulated in breast cancer tissues and breast cancer cell lines. The overexpression of ARHI could inhibit cell proliferation and invasion and induce cell apoptosis. To address whether ARHI is regulated by miR-221 in breast cancer cell lines, the results in this study showed that a significant inverse correlation existed between ARHI and miR-221. MiR-221 displayed an upregulation in breast cancer tissues and breast cancer cell lines. The inhibition of miR-221 induced a significant upregulation of ARHI in MCF-7 cells. To prove a direct interaction between miR-221 and ARHI mRNA, ARHI 3'UTR, which includes the potential target site for miR-221, was cloned downstream of the luciferase reporter gene of the pMIR-REPORT vector to generate the pMIR-ARHI-3'UTR vector. The results confirmed a direct interaction of miR-221 with a target site on the 3'UTR of ARHI. In conclusion, ARHI is a tumor suppressor gene that is downregulated in breast cancer. The overexpression of ARHI could inhibit breast cancer cell proliferation and invasion and induce cell apoptosis. This study demonstrated for the first time that the downregulation of ARHI in breast cancer cells could be regulated by miR-221.

Li BX, Li J, Luo CL, et al.
Expression of JMJD2A in infiltrating duct carcinoma was markedly higher than fibroadenoma, and associated with expression of ARHI, p53 and ER in infiltrating duct carcinoma.
Indian J Exp Biol. 2013; 51(3):208-17 [PubMed] Related Publications
Jumonji Domain Containing 2A (JMJD2A) may be a cancer-associated gene involved in human breast cancer. With a view to investigating expression of JMJD2A in human breast cancer and benign lesion tissues as well as relationship between JMJD2A and tumor related proteins, histological and immunohistochemical analysis, Western blot and quantitative real-time PCR in infiltrating duct carcinoma and fibroadenoma for JMJD2A and immunohistochemical analysis and quantitative real-time PCR in infiltrating duct carcinoma for tumor related proteins (ARHI, p53, ER, PR and CerbB-2) were performed. Histological examination validated the clinical diagnosis. The JMJD2A positive rate of infiltrating duct carcinoma was significantly higher than fibroadenoma by immunohistochemical analysis. The mean optical density of JMJD2A in infiltrating duct carcinoma was higher than fibroadenoma by western blot. JMJD2A mRNA level in infiltrating duct carcinoma was higher than fibroadenoma by quantitative real-time PCR. Spearman correlation analysis revealed that the expression of JMJD2A was associated with ARHI, p53 and ER from immunohistochemical results respectively. Pearson correlation analysis revealed that the expression of JMJD2A was associated with ARHI, p53 and ER from quantitative real-time PCR results respectively. Expression of JMJD2A in infiltrating duct carcinoma was higher, and associated with ARHI, p53 and ER. The results may take JMJD2A as a potential diagnostic and therapeutic target in human breast cancer.

Li J, Cui G, Sun L, et al.
STAT3 acetylation-induced promoter methylation is associated with downregulation of the ARHI tumor-suppressor gene in ovarian cancer.
Oncol Rep. 2013; 30(1):165-70 [PubMed] Related Publications
ARHI is a Ras-related imprinted tumor-suppressor gene that inhibits cancer cell growth and motility. ARHI is downregulated in the majority of ovarian cancer cells, and promoter methylation is considered to be associated with its loss of expression. however, the underlying mechanisms are not well understood. Thus, the present study aimed to investigate the specific functions of ARHI and its methylation in ovarian cancer cell proliferation. Furthermore, we examined the possible role of acetylated STAT3 in modulating the expression of ARHI and its methylation. In accordance with the majority of previous studies, reduced ARHI expression was found in epithelial ovarian cancer tissues and cancer cell lines as indicated by immunohistochemistry and RT-PCR. In addition, CpG islands I and II within ARHI promoter regions were partially methylated or hypermethylated in cancer cell lines (SKOV-3 and HO-8910) as analyzed by pyrosequencing assays, resulting in enhanced proliferation of the cancer cells. This proliferation was reversed by the administration of 5-aza-2'-deoxycytidine. Subsequently, we demonstrated that STAT3 acetylation was increased in HO-8910 cells, and the methylation status of CpG I was altered in response to the acetylation of STAT3 using western blotting. Finally, chromatin immunoprecipitation (ChIP) and IP analysis indicated that acetylated STAT3 bound to the ARHI promoter and recruited DNA methyltransferase 1 for genetic modification. In conclusion, acetylated STAT3-induced promoter gene methylation accounts for the loss of ARHI expression and cancer cell proliferation.

Zhang L, Liu P, Li H, Xue F
Effect of histone deacetylase inhibitors on cell apoptosis and expression of the tumor suppressor genes RUNX3 and ARHI in ovarian tumors.
Mol Med Rep. 2013; 7(5):1705-9 [PubMed] Related Publications
The aim of this study was to investigate the expression of Runt box 3 (RUNX3) and aplasia Ras homolog member I (ARHI) in ovarian tumors, and the effects of histone deacetylase inhibitors (HDACIs) on the expression of these genes and the growth of ovarian cancer cells. The mRNA expression of the RUNX3 and ARHI genes in normal ovaries and ovarian tumors was determined using reverse transcription polymerase chain reaction (RT-PCR). The effects of HDACIs on RUNX3 and ARHI expression in four ovarian cancer cell lines (SKOV3, A2780, COC1 and OC3) were determined using RT-PCR and the MTT assay. The expression of RUNX3 and ARHI in normal ovarian cells was 86 and 100%, respectively. Although the two genes were downregulated in ovarian tumors, the extent of downregulation differed. The expression of RUNX3 and ARHI was correlated with the degree of tumor malignancy (P<0.05). ARHI was expressed in all four ovarian cancer cell lines, whereas RUNX3 was expressed only in the OC3 cell line. Treatment with HDACIs upregulated the expression of ARHI and RUNX3 in the SKOV3 cell line only. In A2780 cells, HDACIs upregulated ARHI expression only in the presence of trichostatin A (TSA) plus cisplatin. HDACIs induced significant apoptosis in ovarian cancer cells, which was inversely correlated with the concentration and duration of treatment (P<0.05). In conclusion, RUNX3 and ARHI were shown to be expressed in normal ovarian cells; however, their expression was downregulated or lost in ovarian tumor cells. The combined detection of ARHI and RUNX3 expression may offer improved prediction and monitoring of ovarian malignancies. HDACIs were revealed to inhibit the growth of ovarian tumor cells and may constitute a novel therapeutic option for ovarian tumors.

Hu YQ, Si LJ, Ye ZS, et al.
Inhibitory effect of ARHI on pancreatic cancer cells and NF-κB activity.
Mol Med Rep. 2013; 7(4):1180-4 [PubMed] Related Publications
The aim of this study was to investigate the effect of aplasia ras homolog member I (ARHI) on proliferation, apoptosis and the cell cycle in the pancreatic cancer cell line PANC-1. The study also aimed to examine the effect of ARHI on the activity of the nuclear factor (NF)-κB and to determine whether ARHI acts as a tumor suppressor in the development of pancreatic cancer by inhibiting the activity of NF-κB. A pIRES2‑EGFP‑ARHI vector, constructed by reverse transcrition (RT)‑PCR, was transiently transfected into the PANC-1 cells and analyzed for the expression of the ARHI protein by western blotting. A MTT assay was used to quantify cell proliferation, and apoptosis was analyzed by flow cytometry. The NF‑κB signaling pathway, specifically the pathway using the nuclear phosphorylated p65 isoform, was analyzed by western blotting. Expression of the ARHI protein was detected by western blotting subsequent to the PANC-1 cells being transiently transfected with the pIRES2‑EGFP‑ARHI construct. Cell proliferation was strongly inhibited in the PANC-1 cells transfected with pIRES2‑EGFP‑ARHI. The cell cycle assays indicated an increase in the number of cells at the G0/G1 phase and a decrease in the cells at the S phase, but the difference was not significant (P>0.05). Time course studies also indicated a marked increase in the apoptotic index following transient transfection, as well as a gradual decrease in the expression of the nuclear phosphorylated p65 protein. ARHI acts as a tumor suppressor by downregulating the NF‑κB signaling pathway, which results in the inhibition of cell proliferation, apoptosis and the cell cycle in the pancreatic tumor PANC-1 cell line.

Zhang S, Feng XL, Shi L, et al.
Genome-wide analysis of DNA methylation in tongue squamous cell carcinoma.
Oncol Rep. 2013; 29(5):1819-26 [PubMed] Related Publications
Tongue squamous cell carcinoma (TSCC) is one of the most common types of oral cancer; however, its molecular mechanisms remain unclear. In this study, methylated DNA immunoprecipitation (MeDIP) coupled with methylation microarray analysis was performed to screen for aberrantly methylated genes in adjacent normal control and TSCC tissues from 9 patients. Roche NimbleGen Human DNA Methylation 385K Promoter Plus CpG Island Arrays were used to detect 28,226 CpG sites. A total of 1,269 hypermethylated CpG sites covering 330 genes and 1,385 hypomethylated CpG sites covering 321 genes were found in TSCC tissue, compared to the adjacent normal tissue. Furthermore, we chose three candidate genes (FBLN1, ITIH5 and RUNX3) and validated the DNA methylation status by methylation-specific PCR (MS-PCR) and the mRNA expression levels by reverse transcription PCR (RT-PCR). In TSCC tissue, FBLN1 and ITIH5 were shown to be hypermethylated and their expression was found to be decreased, and RUNX3 was shown to be hypomethylated, however, its mRNA expression was found to be increased. In addition, another three genes (BCL2L14, CDCP1 and DIRAS3) were tested by RT-PCR. In TSCC tissue, BCL2L14 and CDCP1 expressions were markedly upregulated, and DIRAS3 expression was significantly downregulated. Our data demonstrated that aberrant DNA methylation is observed in TSCC tissue and plays an important role in the tumorigenesis, development and progression of TSCC.

Wu X, Liang L, Dong L, et al.
Effect of ARHI on lung cancer cell proliferation, apoptosis and invasion in vitro.
Mol Biol Rep. 2013; 40(3):2671-8 [PubMed] Related Publications
The purposes of this study were to elucidate the effects of ARHI (aplysia ras homolog I) on several biological features of lung cancer cells, including growth, proliferation and invasion, to collect experimental evidence for the future biological treatment of human lung cancer. The eukaryotic expression vector, pcDNA3.1-ARHI, was constructed and transfected into the human lung cancer cell line SK-MES-1. The biological properties of the resulting ARHI-expressing lung cancer cell line were evaluated using methyl thiazolyl tetrazolium assay, flow cytometry, and a Transwell invasion assay. Additionally, the influence of ARHI on the gene expression levels of cyclin D1, p27(KIP1), death-associated protein kinase 1 (DAPK1), and matrix metalloproteinases1/2 (MMP-1/2) was determined. Compared to the non-transfected SK-MES-1 cells and the cells transfected with the empty pcDNA3.1 plasmid, the ARHI-transfected cells displayed significantly reduced growth rates and decreased viability (P < 0.05). The ARHI-transfected cells also displayed a significantly higher percentage of cells in G1 phase (P < 0.05) and a lower percentage of cells in S phase (P < 0.05); a higher percentage of apoptosis (P < 0.05); and finally, a notable reduction in the basement membrane-penetration rate in the Transwell invasion assay (P < 0.05). Furthermore, it was determined that ARHI is capable of inhibiting the expression of cyclin D1, MMP-1, and MMP-2; however, ARHI promotes the expression of both p27(KIP1) and DAPK1 in SK-MES-1 cells. In conclusion, overexpression of ARHI gene might be associated with the inhibition of lung cancer cell growth, proliferation and invasion, and the promotion of apoptosis.

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