Gene Summary

Gene:GADD45A; growth arrest and DNA-damage-inducible, alpha
Aliases: DDIT1, GADD45
Summary:This gene is a member of a group of genes whose transcript levels are increased following stressful growth arrest conditions and treatment with DNA-damaging agents. The protein encoded by this gene responds to environmental stresses by mediating activation of the p38/JNK pathway via MTK1/MEKK4 kinase. The DNA damage-induced transcription of this gene is mediated by both p53-dependent and -independent mechanisms. Alternatively spliced transcript variants encoding distinct isoforms have been found for this gene.[provided by RefSeq, Dec 2010]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:growth arrest and DNA damage-inducible protein GADD45 alpha
Source:NCBIAccessed: 06 August, 2015


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 06 August 2015 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 06 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

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

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

Latest Publications: GADD45A (cancer-related)

Zhang XY,
Expression of growth arrest and DNA damage inducible 45a in human oral squamous cell carcinoma is associated with tumor progression and clinical outcome.
J Cancer Res Ther. 2014; 10 Suppl:C108-13 [PubMed] Related Publications
OBJECTIVES: The aim of this study was to examine the growth arrest and DNA damage-inducible (Gadd45a) expression and its role in tumor progression, invasion and metastasis in oral squamous cell carcinoma (OSCC).
MATERIALS AND METHODS: Growth arrest and DNA damage-inducible 45a distribution was detected by immunohistochemistry in tumor sections of 106 patients with primary OSCC and sections of adjacent pericancerous tissues from 60 patients among the 106. The association between the Gadd45a expression and clinical prognosis of OSCC were performed by statistical analysis. Gadd45a gene knockdown was performed in Tca8113 cells by small interfering ribonucleic acid treatment and its effects on cell cycle, and migration were detected by Flow Cytometric (Becton Dickinson, USA) and transwell chamber assay respectively.
RESULTS AND CONCLUSION: The results showed that Gadd45a was redistributed to cytoplasm in poorly differentiated carcinoma from its nucleus location in normal tissue (P < 0.05). The expression of Gadd45a was significantly associated with lymph node metastasis, tumor stage and tumor histological grade (P < 0.05). Knockdown of Gadd45a gene abolished the G2/M arrest and increased migrating ability of Tca8113 cell (P < 0.05). The results indicate that Gadd45a play an important role in OSCC metastasis by affecting the bioactivity of the tumor cells, and its distribution may serve for the prediction of clinical outcome of OSCC.

Nair RS, Kuriakose M, Somasundaram V, et al.
The molecular response of vanadium complexes of nicotinoyl hydrazone in cervical cancers--a possible interference with HPV oncogenic markers.
Life Sci. 2014; 116(2):90-7 [PubMed] Related Publications
AIMS: Hydrazones belonging to the class of NNO donor Schiff bases are reported to have extensive anti-viral activity and anti-neoplastic activity against certain cancers such as colon cancer, hepatocellular carcinoma and testicular cancer. Here we aim to study the possible effects of two novel nicotinoyl hydrazones on Human papillomavirus (HPV) infected cervical cancers.
MAIN METHODS: The effect of vanadium complexes on the proliferation of SiHa and HeLa cells was analyzed using MTT assay. The apoptotic potentials of the complexes were assessed by their ability to induce DNA condensation as well as loss of mitochondrial membrane potential. Caspase activity assay and DNA content analysis were performed to understand the mechanism of apoptotic induction. RT-PCR analysis of cell cycle genes, GADD45, p53, p21 and HPV specific oncogenes, E6 and E7 were used to elucidate the molecular mechanism of the complexes.
KEY FINDINGS: OVK 49 exhibits an increased apoptosis inducing potential when compared to OVK 89 in HPV16 positive SiHa cells compared to HPV18 positive HeLa. A down regulation for E6 and E7 mRNA transcripts along with the induction of p53 protein in SiHa cells were observed when treated with OVK 49 indicating that OVK 49 might have promising anti-cancer activity against HPV16 positive cervical cancers.
SIGNIFICANCE: This is the first study demonstrating that vanadium complexes could induce a p53 dependent apoptotic mechanism in high risk HPV16-positive cervical cancers.

Antal O, Hackler L, Shen J, et al.
Combination of unsaturated fatty acids and ionizing radiation on human glioma cells: cellular, biochemical and gene expression analysis.
Lipids Health Dis. 2014; 13:142 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Based on previous observations a potential resort in the therapy of the particularly radioresistant glioma would be its treatment with unsaturated fatty acids (UFAs) combined with irradiation.
METHODS: We evaluated the effect of different UFAs (arachidonic acid (AA), docosahexaenoic acid (DHA), gamma-linolenic acid (GLA), eicosapentaenoic acid (EPA) and oleic acid (OA)) on human U87 MG glioma cell line by classical biochemical end-point assays, impedance-based, real-time cellular and holographic microscopic analysis. We further analyzed AA, DHA, and GLA at morphological, gene and miRNA expression level.
RESULTS: Corresponding to LDH-, MTS assays and real-time cytoxicity profiles AA, DHA, and GLA enhanced the radio sensitivity of glioma cells. The collective application of polyunsaturated fatty acids (PUFAs) and irradiation significantly changed the expression of EGR1, TNF-α, NOTCH1, c-MYC, TP53, HMOX1, AKR1C1, NQO1, while up-regulation of GADD45A, EGR1, GRP78, DDIT3, c-MYC, FOSL1 were recorded both in response to PUFA treatment or irradiation alone. Among the analyzed miRNAs miR-146 and miR-181a were induced by DHA treatment. Overexpression of miR-146 was also detected by combined treatment of GLA and irradiation.
CONCLUSIONS: Because PUFAs increased the radio responsiveness of glioma cells as assessed by biochemical and cellular assays, they might increase the therapeutic efficacy of radiation in treatment of gliomas. We demonstrated that treatment with DHA, AA and GLA as adjunct to irradiation up-regulated the expression of oxidative-stress and endoplasmic reticulum stress related genes, and affected NOTCH1 expression, which could explain their additive effects.

Binse I, Ueberberg B, Sandalcioglu IE, et al.
Expression analysis of GADD45γ, MEG3, and p8 in pituitary adenomas.
Horm Metab Res. 2014; 46(9):644-50 [PubMed] Related Publications
Preceding studies have indicated that aberrant expression levels rather than genetic changes of GADD45γ, MEG3, and p8 gene might play a role in the pathogenesis of pituitary adenomas. We analysed their expression in various normal human tissues and in different pituitary tumour types, and investigated GADD45γ mutations in a subset of adenomas. Absolute quantification by real-time RT-PCR was performed in 24 normal tissues as well as in 34 nonfunctioning, 24 somatotroph, 12 corticotroph adenomas, 4 prolactinomas, 1 FSHoma, and in 6 normal pituitaries. Furthermore, we investigated the relationship between clinical data and gene expression. A subset was screened for GADD45γ mutations by single strand conformation polymorphism analysis (SSCP) and sequencing. All normal human tissues expressed GADD45γ, MEG3, and p8 mRNA. For GADD45γ, significantly lower expression levels were found in nonfunctioning adenomas compared with normal pituitary and somatotroph adenomas. P8 and MEG3 mRNA levels were significantly lower in nonfunctioning and corticotroph adenomas compared with normal pituitary. Expression of GADD45γ was significantly higher in pituitary adenomas of female patients. No mutation was found in the GADD45γ gene. GADD45γ, MEG3, and p8 appear to have physiological functions in a variety of human tissues. GADD45γ, MEG3, and P8 may be involved in the pathogenesis of nonfunctioning and corticotroph pituitary tumours. Female gender seems to predispose to slightly higher GADD45γ expression in pituitary adenomas. Mutations of the GADD45γ are unlikely to be involved in the pathogenesis of pituitary adenomas.

Arab K, Park YJ, Lindroth AM, et al.
Long noncoding RNA TARID directs demethylation and activation of the tumor suppressor TCF21 via GADD45A.
Mol Cell. 2014; 55(4):604-14 [PubMed] Related Publications
DNA methylation is a dynamic and reversible process that governs gene expression during development and disease. Several examples of active DNA demethylation have been documented, involving genome-wide and gene-specific DNA demethylation. How demethylating enzymes are targeted to specific genomic loci remains largely unknown. We show that an antisense lncRNA, termed TARID (for TCF21 antisense RNA inducing demethylation), activates TCF21 expression by inducing promoter demethylation. TARID interacts with both the TCF21 promoter and GADD45A (growth arrest and DNA-damage-inducible, alpha), a regulator of DNA demethylation. GADD45A in turn recruits thymine-DNA glycosylase for base excision repair-mediated demethylation involving oxidation of 5-methylcytosine to 5-hydroxymethylcytosine in the TCF21 promoter by ten-eleven translocation methylcytosine dioxygenase proteins. The results reveal a function of lncRNAs, serving as a genomic address label for GADD45A-mediated demethylation of specific target genes.

Su LY, Xin HY, Liu YL, et al.
Anticancer bioactive peptide (ACBP) inhibits gastric cancer cells by upregulating growth arrest and DNA damage-inducible gene 45A (GADD45A).
Tumour Biol. 2014; 35(10):10051-6 [PubMed] Related Publications
Recently, we reported that anticancer bioactive peptide (ACBP), purified from goat spleens immunized with human gastric cancer extracts, significantly inhibited gastric cancer cells in vitro and gastric tumors in vivo via repressing cell growth and promoting apoptosis, making it a promising potential biological anticancer drug. However, it is not known what genes are functionally required for the ACBP effects. Here, we first found that two tumor suppressor genes, cyclin-dependent kinase inhibitor 2B (CDKN2B) and growth arrest and DNA damage-inducible alpha (GADD45A), were upregulated significantly in the cells with ACBP treatment by microarray screening and the findings were validated by real-time RT-PCR. Next, GADD45A mRNA and protein expressions were downregulated in the gastric cancer cells by lentivirus-mediated RNAi; then, cell viability, cell cycle, and apoptosis were assayed by MTT and flow cytometry. Interestingly, our results indicated that cell viability was not dependent on GADD45A without ACBP treatment; however, cell sensitivity to ACBP was significantly decreased in ACBP-treated gastric cancer cells with GADD45A downregulation. Therefore, we demonstrate that GADD45A was functionally required for ACBP to inhibit gastric cancer cells, suggesting that GADD45A may become a biomarker for ACBP sensitivity. Our findings have significant implications on the molecular mechanism understanding, biomarker development, and anticancer drug development of ACBP.

Calderon MR, Verway M, Benslama RO, et al.
Ligand-dependent corepressor contributes to transcriptional repression by C2H2 zinc-finger transcription factor ZBRK1 through association with KRAB-associated protein-1.
Nucleic Acids Res. 2014; 42(11):7012-27 [PubMed] Free Access to Full Article Related Publications
We identified a novel interaction between ligand-dependent corepressor (LCoR) and the corepressor KRAB-associated protein-1 (KAP-1). The two form a complex with C2H2 zinc-finger transcription factor ZBRK1 on an intronic binding site in the growth arrest and DNA-damage-inducible α (GADD45A) gene and a novel site in the fibroblast growth factor 2 (FGF2) gene. Chromatin at both sites is enriched for histone methyltransferase SETDB1 and histone 3 lysine 9 trimethylation, a repressive epigenetic mark. Depletion of ZBRK1, KAP-1 or LCoR led to elevated GADD45A and FGF2 expression in malignant and non-malignant breast epithelial cells, and caused apoptotic death. Loss of viability could be rescued by simultaneous knockdowns of FGF2 and transcriptional coregulators or by blocking FGF2 function. FGF2 was not concurrently expressed with any of the transcriptional coregulators in breast malignancies, suggesting an inverse correlation between their expression patterns. We propose that ZBRK1, KAP-1 and LCoR form a transcriptional complex that silences gene expression, in particular FGF2, which maintains breast cell viability. Given the broad expression patterns of both LCoR and KAP-1 during development and in the adult, this complex may have several regulatory functions that extend beyond cell survival, mediated by interactions with ZBRK1 or other C2H2 zinc-finger proteins.

Qiang W, Jin T, Yang Q, et al.
PRIMA-1 selectively induces global DNA demethylation in p53 mutant-type thyroid cancer cells.
J Biomed Nanotechnol. 2014; 10(7):1249-58 [PubMed] Related Publications
The p53 tumor suppressor pathway blocks carcinogenesis by triggering apoptosis and cellular senescence in response to oncogenic stress. Over 50% of human cancers including thyroid cancer carry loss-of-function mutations in the p53 gene. Recently, the identification of mutant p53-reactivating small molecules such as PRIMA-1 (p53 reactivation and induction of massive apoptosis) renders possibilities for the development of more efficient anticancer drugs. Although PRIMA-1 has been widely used for cancer therapy and exhibits a promising anticancer activity, its biological effect, particularly the epigenetic aspect, remains to be well elucidated. The present study attempts to explore the effect of PRIMA-1 on DNA methylation in a panel of thyroid cancer cell lines using luminometric methylation assay (LUMA). Our results showed that only p53 mutant-type cells were inhibited upon PRIMA-1 treatment. Conversely, p53 wild-type cells were non-sensitive to PRIMA-1. Moreover, our data demonstrated that PRIMA-1 selectively induced significant global DNA demethylation in p53 mutant-type cells. Mechanically, PRIMA-1 induced global DNA demethylation in these cells mainly through inhibiting the expression of DNA methyltransferase (DNMT) 1, 3a and 3b, and upregulating the expression of GADD45a. Notably, PRIMA-1 dramatically increased the expression of the ten-eleven translocation (TET) family of 5mC-hydroxylases, particularly TET1, in p53 mutant-type cells, further contributing to DNA demethylation. Thus, this study uncovered a previously unrecognized and prominent biological effect of PRIMA-1 through which it can cause global DNA demethylation in p53 mutant-type cancer cells mainly by rescuing the function of mutant p53 protein.

Chu TY, Yang JT, Huang TH, Liu HW
Crosstalk with cancer-associated fibroblasts increases the growth and radiation survival of cervical cancer cells.
Radiat Res. 2014; 181(5):540-7 [PubMed] Related Publications
Crosstalk between cancer cells and the surrounding cancer associated fibroblasts (CAFs) plays an illusive role in cancer radiotherapy. This study investigated the effect of cancer cell-cancer associated fibroblasts crosstalk on the proliferation and survival of irradiated cervical cancer cells. A pretreatment with conditioned medium from a mixed culture of CAF and HeLa cells (mixCAF) had a stronger effect on enhancing the proliferation and survival of irradiated HeLa cells compared to pretreatment with CAF conditioned medium alone. In addition, pretreatment with a mixed culture of CAF and HeLa cells conditioned medium reduced the levels of two major radiation-induced genes, GADD45 and BTG2, and phosphorylation of p38. Profiling of the growth and survival factors in the conditioned medium revealed PDGF and VEGF, and IGF2, EGF, FGF-4, IGFBPs and GM-CSF to be specifically secreted from HeLa cells and CAFs, respectively. This study demonstrated radiation protective effects of CAF-cancer cell crosstalk, and identified multiple growth factors and radiation response genes that might be involved in these effects.

Park GB, Choi Y, Kim YS, et al.
Silencing of PKCη induces cycle arrest of EBV(+) B lymphoma cells by upregulating expression of p38-MAPK/TAp73/GADD45α and increases susceptibility to chemotherapeutic agents.
Cancer Lett. 2014; 350(1-2):5-14 [PubMed] Related Publications
PKCη is involved in proliferation, differentiation, and drug resistance. However, PKCη function in EBV(+) B lymphoma remains poorly understood. Gene silencing of PKCη through siRNA knockdown inhibited cellular proliferation, induced cell cycle arrest in G0/G1 and G2/M phases, and sensitized cells to chemotherapeutic drugs. Upon PKCη knockdown, expression levels of p21, GADD45α, and TAp73 were all increased, whereas expression levels of CDK2, CDK4, CDK6, cyclin E, cyclin B1, and cdc2 were all downregulated. PKCη silencing also activated p38-MAPK, which in turn contributed to the expression of cell cycle arrest-related molecules. These results suggest that siRNA-mediated silencing of PKCη can be a potent tool to complement existing chemotherapy regimens for treating EBV(+) B lymphoma.

Hsu YC, Huang TY, Chen MJ
Therapeutic ROS targeting of GADD45γ in the induction of G2/M arrest in primary human colorectal cancer cell lines by cucurbitacin E.
Cell Death Dis. 2014; 5:e1198 [PubMed] Free Access to Full Article Related Publications
Cucurbitacin E (CuE) or α-elaterin is a natural compound previously shown to be an antifeedant as well as a potent chemopreventive agent against several types of cancer. The present study investigated the anticancer effects of CuE on colorectal cancer (CRC) using primary cell lines isolated from five CRC patients in Taiwan, Specifically, we explored the anti-proliferation and cell cycle G2/M arrest induced by CuE in CRC cells. MPM-2 flow cytometry tests show that CuE-treated cells accumulated in metaphase (CuE 2.5-7.5 μM). Results further indicate that CuE produced G2/M arrest as well as the downregulation of CDC2 and cyclin B1 expression and dissociation. Both effects increased proportionally with the dose of CuE; however, the inhibition of proliferation, arrest of mitosis, production of reactive oxygen species (ROS), and loss of mitochondrial membrane potential (ΔΨm) were found to be dependent on the quantity of CuE used to treat the cancer cells. In addition, cell cycle arrest in treated cells coincided with the activation of the gene GADD45(α, β, γ). Incubation with CuE resulted in the binding of GADD45γ to CDC2, which suggests that the delay in CuE-induced mitosis is regulated by the overexpression of GADD45γ. Our findings suggest that, in addition to the known effects on cancer prevention, CuE may have antitumor activities in established CRC.

Xiu P, Xu Z, Liu F, et al.
Downregulating sCLU enhances the sensitivity of hepatocellular carcinoma cells to gemcitabine by activating the intrinsic apoptosis pathway.
Dig Dis Sci. 2014; 59(8):1798-809 [PubMed] Related Publications
PURPOSE: The purpose of this study was to investigate whether the therapeutic activity of gemcitabine (GCB) in hepatocellular carcinoma (HCC) could be increased by the down-regulation of secretory clusterin (sCLU), a glycoprotein that is considered to play a cytoprotective role in the resistance to chemotherapy.
METHODS: The expression of sCLU was detected in HCC tumor tissues and cell lines. A cell viability and apoptosis assay were performed in parental HCC cells or the same cells transfected with sCLU shRNA and treated with or without GCB. The potential downstream pathways were investigated using the Human Apoptosis RT(2) Profiler™ PCR Array.
RESULTS: The expression levels of sCLU in HCC tissues were significantly higher than in adjacent non-tumor liver tissues and were associated with the histological grade and transarterial chemoembolization. sCLU overexpression was also found in three HCC cell lines and hepatocytes. The depletion of sCLU synergistically increased GCB sensitivity in Bel7402 and SMMC7721 cells and induced cell apoptosis. Based on the PCR array analysis, sCLU depletion also resulted in the up-regulation of BNIP1, GADD45A, TNFRSF10A, and TRADD and down-regulation of AKT1 in Bel7402 and SMMC7721 cells compared with the parental controls. These results were further supported by a Western blot analysis, which showed increased GADD45a protein expression and the decreased expression of phosphorylated AKT. GADD45a overexpression also increased the sensitivity to GCB in the Bel7402 and SMMC7721 cells.
CONCLUSION: Targeting sCLU may be a useful method to enhance the cytotoxic effect of GCB in hepatocellular carcinoma.

Pei N, Jie F, Luo J, et al.
Gene expression profiling associated with angiotensin II type 2 receptor-induced apoptosis in human prostate cancer cells.
PLoS One. 2014; 9(3):e92253 [PubMed] Free Access to Full Article Related Publications
Increased expression of angiotensin II type 2 receptor (AT2R) induces apoptosis in numerous tumor cell lines, with either Angiotensin II-dependent or Angiotensin II-independent regulation, but its molecular mechanism remains poorly understood. Here, we used PCR Array analysis to determine the gene and microRNA expression profiles in human prostate cancer cell lines transduced with AT2R recombinant adenovirus. Our results demonstrated that AT2R over expression leads to up-regulation of 6 apoptosis-related genes (TRAIL-R2, BAG3, BNIPI, HRK, Gadd45a, TP53BP2), 2 cytokine genes (IL6 and IL8) and 1 microRNA, and down-regulation of 1 apoptosis-related gene TNFSF10 and 2 cytokine genes (BMP6, BMP7) in transduced DU145 cells. HRK was identified as an up-regulated gene in AT2R-transduced PC-3 cells by real-time RT-PCR. Next, we utilized siRNAs to silence the up-regulated genes to further determine their roles on AT2R overexpression mediated apoptosis. The results showed downregulation of Gadd45a reduced the apoptotic effect by ∼30% in DU145 cells, downregulation of HRK reduced AT2R-mediated apoptosis by more than 50% in PC-3 cells, while downregulation of TRAIL-R2 enhanced AT2R-mediated apoptosis more than 4 times in DU145 cells. We also found that the effects on AT2R-mediated apoptosis caused by downregulation of Gadd45a, TRAIL-R2 and HRK were independent in activation of p38 MAPK, p44/42 MAPK and p53. Taken together, our results demonstrated that TRAIL-R2, Gadd45a and HRK may be novel target genes for further study of the mechanism of AT2R-mediated apoptosis in prostate cancer cells.

Hsu YC, Chen MJ, Huang TY
Inducement of mitosis delay by cucurbitacin E, a novel tetracyclic triterpene from climbing stem of Cucumis melo L., through GADD45γ in human brain malignant glioma (GBM) 8401 cells.
Cell Death Dis. 2014; 5:e1087 [PubMed] Free Access to Full Article Related Publications
Cucurbitacin E (CuE) is a natural compound previously shown to have anti-feedant, antioxidant and antitumor activities as well as a potent chemo-preventive action against cancer. The present study investigates its anti-proliferative property using MTT assay; CuE demonstrated cytotoxic activity against malignant glioma GBM 8401 cells and induced cell cycle G2/M arrest in these cells. CuE-treated cells accumulated in metaphase (CuE 2.5-10 μM) as determined using MPM-2 by flow cytometry. We attempted to characterize the molecular pathways responsible for cytotoxic effects of CuE in GBM 8401 cells. We studied the genome-wide gene expression profile on microarrays and molecular networks by using pathway analysis tools of bioinformatics. The CuE reduced the expression of 558 genes and elevated the levels of 1354 genes, suggesting an existence of the common pathways involved in induction of G2/M arrest. We identified the RB (GADD45β and GADD45γ) and the p53 (GADD45α) signaling pathways as the common pathways, serving as key molecules that regulate cell cycle. Results indicate that CuE produced G2/M arrest as well as the upregulation of GADD45 γ and binding with CDC2. Both effects increased proportionally with the dose of CuE, suggesting that the CuE-induced mitosis delay is regulated by GADD45γ overexpression. Our findings suggest that, in addition to the known effects on cancer prevention, CuE may have antitumor activity in glioma therapy.

Guerzoni C, Amatori S, Giorgi L, et al.
An aza-macrocycle containing maltolic side-arms (maltonis) as potential drug against human pediatric sarcomas.
BMC Cancer. 2014; 14:137 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Identification of new drugs against paediatric sarcomas represents an urgent clinical need that mainly relies on public investments due to the rarity of these diseases. In this paper we evaluated the in vitro and in vivo efficacy of a new maltol derived molecule (maltonis), belonging to the family of molecules named hydroxypyrones.
METHODS: Maltonis was screened for its ability to induce structural alteration of DNA molecules in comparison to another maltolic molecule (malten). In vitro antitumour efficacy was tested using a panel of sarcoma cell lines, representative of Ewing sarcoma, osteosarcoma and rhabdomyosarcoma, the three most common paediatric sarcomas, and in normal human mesenchymal primary cell cultures. In vivo efficacy was tested against TC-71 Ewing sarcoma xenografts.
RESULTS: Maltonis, a soluble maltol-derived synthetic molecule, was able to alter the DNA structure, inhibit proliferation and induce apoptotic cell death in paediatric sarcoma cells, either sensitive or resistant to some conventional chemotherapeutic drugs, such as doxorubicin and cisplatin. In addition, maltonis was able to induce: i) p21, p15 and Gadd45a mRNA upregulation; ii) Bcl-2, survivin, CDK6 and CDK8 down-regulation; iii) formation of γ-H2AX nuclear foci; iv) cleavage of PARP and Caspase 3. Two independent in vivo experiments demonstrated the tolerability and efficacy of maltonis in the inhibition of tumour growth. Finally maltonis was not extruded by ABCB1, one of the major determinants of chemotherapy failure, nor appeared to be a substrate of the glutathione-related detoxification system.
CONCLUSIONS: Considering that treatment of poorly responsive patients still suffers for the paucity of agents able to revert chemoresistance, maltonis may be considered for the future development of new therapeutic approaches for refractory metastatic patients.

Lee WJ, Kim SC, Lee SJ, et al.
Investigating the different mechanisms of genotoxic and non-genotoxic carcinogens by a gene set analysis.
PLoS One. 2014; 9(1):e86700 [PubMed] Free Access to Full Article Related Publications
Based on the process of carcinogenesis, carcinogens are classified as either genotoxic or non-genotoxic. In contrast to non-genotoxic carcinogens, many genotoxic carcinogens have been reported to cause tumor in carcinogenic bioassays in animals. Thus evaluating the genotoxicity potential of chemicals is important to discriminate genotoxic from non-genotoxic carcinogens for health care and pharmaceutical industry safety. Additionally, investigating the difference between the mechanisms of genotoxic and non-genotoxic carcinogens could provide the foundation for a mechanism-based classification for unknown compounds. In this study, we investigated the gene expression of HepG2 cells treated with genotoxic or non-genotoxic carcinogens and compared their mechanisms of action. To enhance our understanding of the differences in the mechanisms of genotoxic and non-genotoxic carcinogens, we implemented a gene set analysis using 12 compounds for the training set (12, 24, 48 h) and validated significant gene sets using 22 compounds for the test set (24, 48 h). For a direct biological translation, we conducted a gene set analysis using Globaltest and selected significant gene sets. To validate the results, training and test compounds were predicted by the significant gene sets using a prediction analysis for microarrays (PAM). Finally, we obtained 6 gene sets, including sets enriched for genes involved in the adherens junction, bladder cancer, p53 signaling pathway, pathways in cancer, peroxisome and RNA degradation. Among the 6 gene sets, the bladder cancer and p53 signaling pathway sets were significant at 12, 24 and 48 h. We also found that the DDB2, RRM2B and GADD45A, genes related to the repair and damage prevention of DNA, were consistently up-regulated for genotoxic carcinogens. Our results suggest that a gene set analysis could provide a robust tool in the investigation of the different mechanisms of genotoxic and non-genotoxic carcinogens and construct a more detailed understanding of the perturbation of significant pathways.

Ju Y, Xu T, Zhang H, Yu A
FOXO1-dependent DNA damage repair is regulated by JNK in lung cancer cells.
Int J Oncol. 2014; 44(4):1284-92 [PubMed] Related Publications
DNA damage or mutation in cells contributes to tumorigenesis. The transcription factor FOXO1 modulates the expression of genes involved in DNA damage repair, cell cycle arrest and apoptosis. The transcriptional activity of FOXO1 is fundamentally regulated by post-translational modification and subcellular localization. H1299 lung cancer cells were treated with the alkylating agent MNNG, and the cell viability and DNA damage were separately determined by MTT and comet assay. Using immunofluorescence and western blotting, we observed the subcellular localization of FOXO1 and measured the relevant protein expression levels, respectively. To examine cell cycle arrest and apoptosis, flow cytometry analysis was preformed. The interaction between FOXO1 and JNK was analyzed through immunoprecipitation. Our results showed that cell viability was reduced at 24 h after MNNG treatment, and appeared to recover to some degree at 48 h. The increased expression and nuclear export of FOXO1 emerged at 4 h after the treatment. Nuclear FOXO1 played a pivotal role in cell cycle arrest, apoptosis and DNA damage repair by upregulating p27(Kip1), Bim and GADD45 gene expression, respectively. AKT-dependent S256 phosphorylation of FOXO1 and the S473 phosphorylation of AKT were both enhanced following DNA damage. Moreover, our studies revealed that FOXO1 directly interacted with JNK, and the inhibition of the JNK activity led to decreased expression of FOXO1 target genes. These findings suggest for the first time that FOXO1 is a promising candidate substrate for JNK, and the FOXO1-dependent DNA damage repair may be regulated positively by the JNK pathway in H1299 lung cancer cells.

Yong KJ, Milenic DE, Baidoo KE, et al.
Gene expression profiling upon (212) Pb-TCMC-trastuzumab treatment in the LS-174T i.p. xenograft model.
Cancer Med. 2013; 2(5):646-53 [PubMed] Free Access to Full Article Related Publications
Recent studies have demonstrated that therapy with (212) Pb-TCMC-trastuzumab resulted in (1) induction of apoptosis, (2) G2/M arrest, and (3) blockage of double-strand DNA damage repair in LS-174T i.p. (intraperitoneal) xenografts. To further understand the molecular basis of the cell killing efficacy of (212) Pb-TCMC-trastuzumab, gene expression profiling was performed with LS-174T xenografts 24 h after exposure to (212) Pb-TCMC-trastuzumab. DNA damage response genes (84) were screened using a quantitative real-time polymerase chain reaction array (qRT-PCR array). Differentially regulated genes were identified following exposure to (212) Pb-TCMC-trastuzumab. These included genes involved in apoptosis (ABL, GADD45α, GADD45γ, PCBP4, and p73), cell cycle (ATM, DDIT3, GADD45α, GTSE1, MKK6, PCBP4, and SESN1), and damaged DNA binding (DDB) and repair (ATM and BTG2). The stressful growth arrest conditions provoked by (212) Pb-TCMC-trastuzumab were found to induce genes involved in apoptosis and cell cycle arrest in the G2/M phase. The expression of genes involved in DDB and single-strand DNA breaks was also enhanced by (212) Pb-TCMC-trastuzumab while no modulation of genes involved in double-strand break repair was apparent. Furthermore, the p73/GADD45 signaling pathway mediated by p38 kinase signaling may be involved in the cellular response, as evidenced by the enhanced expression of genes and proteins of this pathway. These results further support the previously described cell killing mechanism by (212) Pb-TCMC-trastuzumab in the same LS-174T i.p. xenograft. Insight into these mechanisms could lead to improved strategies for rational application of radioimmunotherapy using α-particle emitters.

Ma L, Liu J, Liu L, et al.
Overexpression of the transcription factor MEF2D in hepatocellular carcinoma sustains malignant character by suppressing G2-M transition genes.
Cancer Res. 2014; 74(5):1452-62 [PubMed] Related Publications
The underlying molecular pathogenesis in hepatocellular carcinoma remains poorly understood. The transcription factor MEF2D promotes survival in various cell types and it seems to function as an oncogene in leukemia. However, its potential contributions to solid cancers have not been explored. In this study, we investigated MEF2D expression and function in hepatocellular carcinoma, finding that MEF2D elevation in hepatocellular carcinoma clinical specimens was associated with poor prognosis. MEF2D-positive primary hepatocellular carcinoma cells displayed a faster proliferation rate compared with MEF2D-negative cells, and silencing or promoting MEF2D expression in these settings limited or accelerated cell proliferation, respectively. Notably, MEF2D-silencing abolished hepatocellular carcinoma tumorigenicity in mouse xenograft models. Mechanistic investigations revealed that MEF2D-silencing triggered G2-M arrest in a manner associated with direct downregulation of the cell-cycle regulatory genes RPRM, GADD45A, GADD45B, and CDKN1A. Furthermore, we identified MEF2D as an authentic target of miR-122, the reduced expression of which in hepatocellular carcinoma may be responsible for MEF2D upregulation. Together, our results identify MEF2D as a candidate oncogene in hepatocellular carcinoma and a potential target for hepatocellular carcinoma therapy.

Pishas KI, Neuhaus SJ, Clayer MT, et al.
Nutlin-3a efficacy in sarcoma predicted by transcriptomic and epigenetic profiling.
Cancer Res. 2014; 74(3):921-31 [PubMed] Related Publications
Nutlin-3a is a small-molecule antagonist of p53/MDM2 that is being explored as a treatment for sarcoma. In this study, we examined the molecular mechanisms underlying the sensitivity of sarcomas to Nutlin-3a. In an ex vivo tissue explant system, we found that TP53 pathway alterations (TP53 status, MDM2/MDM4 genomic amplification/mRNA overexpression, MDM2 SNP309, and TP53 SNP72) did not confer apoptotic or cytostatic responses in sarcoma tissue biopsies (n = 24). Unexpectedly, MDM2 status did not predict Nutlin-3a sensitivity. RNA sequencing revealed that the global transcriptomic profiles of these sarcomas provided a more robust prediction of apoptotic responses to Nutlin-3a. Expression profiling revealed a subset of TP53 target genes that were transactivated specifically in sarcomas that were highly sensitive to Nutlin-3a. Of these target genes, the GADD45A promoter region was shown to be hypermethylated in 82% of wild-type TP53 sarcomas that did not respond to Nutlin-3a, thereby providing mechanistic insight into the innate ability of sarcomas to resist apoptotic death following Nutlin-3a treatment. Collectively, our findings argue that the existing benchmark biomarker for MDM2 antagonist efficacy (MDM2 amplification) should not be used to predict outcome but rather global gene expression profiles and epigenetic status of sarcomas dictate their sensitivity to p53/MDM2 antagonists.

Germani A, Matrone A, Grossi V, et al.
Targeted therapy against chemoresistant colorectal cancers: Inhibition of p38α modulates the effect of cisplatin in vitro and in vivo through the tumor suppressor FoxO3A.
Cancer Lett. 2014; 344(1):110-8 [PubMed] Related Publications
Chemoresistance is a major obstacle to effective therapy against colorectal cancer (CRC) and may lead to deadly consequences. The metabolism of CRC cells depends highly on the p38 MAPK pathway, whose involvement in maintaining a chemoresistant behavior is currently being investigated. Our previous studies revealed that p38α is the main p38 isoform in CRC cells. Here we show that p38α pharmacological inhibition combined with cisplatin administration decreases colony formation and viability of cancer cells and strongly increases Bax-dependent apoptotic cell death by activating the tumor suppressor protein FoxO3A. Our results indicate that FoxO3A activation up-regulates transcription of its target genes (p21, PTEN, Bim and GADD45), which forces both chemosensitive and chemoresistant CRC cells to undergo apoptosis. Additionally, we found that FoxO3A is required for apoptotic cell death induction, as confirmed by RNA interference experiments. In animal models xenografted with chemoresistant HT29 cells, we further confirmed that the p38-targeted dual therapy strategy produced an increase in apoptosis in cancer tissue leading to tumor regression. Our study uncovers a major role for the p38-FoxO3A axis in chemoresistance, thereby suggesting a new therapeutic approach for CRC treatment; moreover, our results indicate that Bax status may be used as a predictive biomarker.

Pickhard A, Piontek G, Seidl C, et al.
²¹³Bi-anti-EGFR radioimmunoconjugates and X-ray irradiation trigger different cell death pathways in squamous cell carcinoma cells.
Nucl Med Biol. 2014; 41(1):68-76 [PubMed] Related Publications
INTRODUCTION: Treatment of patients with squamous cell carcinoma of head and neck is hampered by resistance of tumor cells to irradiation. Additional therapies enhancing the effect of X-ray irradiation may be beneficial. Antibodies targeting EGFR have been shown to improve the efficacy of radiation therapy. Therefore, we analyzed cytotoxicity of (213)Bi-anti-EGFR immunoconjugates in combination with X-ray irradiation.
METHODS: The monoclonal anti-EGFR antibody matuzumab was coupled to CHX-A"-DTPA forming stable complexes with (213)Bi. Cytotoxicity of X-ray radiation, of treatment with (213)Bi-anti-EGFR monoclonal antibodies (MAb) or of a combined treatment regimen was assayed using cell proliferation and colony formation assays in UD-SCC5 cells. Key proteins of cell-cycle arrest and cell death were examined by Western blot analysis. Cell cycle analysis was performed by flow cytometry. DNA double-strand breaks were detected via γH2AX and quantified using Definiens™ software.
RESULTS: Irradiation with X-rays or treatment with (213)Bi-anti-EGFR-MAb resulted in median lethal dose (LD50) values of 12 Gy or 130 kBq/mL, respectively. Treatment with 37 kBq/mL of (213)Bi-anti-EGFR-MAb or 2 Gy of X-rays had only little effect on colony formation of UD-SCC5 cells. In contrast, a combined treatment regimen (37 kBq/mL plus 2 Gy) significantly decreased colony formation and enhanced the formation of DNA double-strand breaks. As revealed by flow cytometry, radiation treatments caused accumulation of cells in the G0/G1 phase. Both treatment with (213)Bi-anti-EGFR immunoconjugates and application of the combined treatment regimen triggered activation of genes of signaling pathways involved in cell-cycle arrest and induction of apoptosis like p21/Waf, GADD45, Puma and Bax, which were only marginally modulated by X-ray irradiation of cells.
CONCLUSIONS: (213)Bi-anti-EGFR-MAb enhances cytotoxicity of X-ray irradiation in UD-SCC5 cells most probably due to effective induction of DNA double-strand breaks. Induction of genes involved in cell-cycle arrest and cell death is almost exclusively due to (213)Bi-anti-EGFR-MAb and seems to be independent of p53 function.

Tian J, Locker J
Gadd45 in the liver: signal transduction and transcriptional mechanisms.
Adv Exp Med Biol. 2013; 793:69-80 [PubMed] Related Publications
Injury and growth stimulation both remarkably increase the hepatic expression of Gadd45β. In liver cancer, promoter methylation frequently silences Gadd45β, demonstrating due to a suppressive function that is often proapoptotic. This contrasts with normal hepatocytes, where Gadd45β facilitates cell survival, growth, and proliferation. Gadd45β binds MKK7-downstream of TNFα and its receptors-to prevent this kinase from activating JNK2. Hence, the Gadd45b-/- genotype increases cell injury and decreases cell proliferation during liver regeneration (i.e., compensatory growth and proliferation). Liver hyperplasia (i.e., de novo growth and proliferation) is an alternate form of growth, caused by drugs that activate the nuclear receptor, CAR. As in regeneration, the Gadd45b-/- genotype considerably slows growth during hyperplasia. However, there is no injury and the slowing occurs because Gadd45β normally binds to CAR and activates its transcriptional stimulation. Thus, Gadd45β protects the liver through two entirely different processes: binding MKK7 to block damaging signal transduction or binding CAR to coactivate anabolic transcription.

Hoffman B, Liebermann DA
Gadd45 in modulation of solid tumors and leukemia.
Adv Exp Med Biol. 2013; 793:21-33 [PubMed] Related Publications
The stress response gadd45 gene family participates in cell cycle control, cell survival, apoptosis, maintenance of genomic stability, DNA repair, and active DNA demethylation, in response to environmental and physiological stress including oncogenic stress. Given these diverse functions, it is anticipated that gadd45 genes can influence the initiation and progression of malignancy and the response to different treatments. This chapter will provide an overview of how the different members of the gadd45 gene family are expressed in different tumors and leukemia, how this may impact on progression of disease, and what happens when expression is manipulated. Studies from human tumor/leukemia samples, cell lines, and animal models are included in this review. An overriding theme is that each of the gadd45 genes has both tumor suppressor and tumor promoter functions, dependent on the tissue/cell type and transforming event.

Salvador JM, Brown-Clay JD, Fornace AJ
Gadd45 in stress signaling, cell cycle control, and apoptosis.
Adv Exp Med Biol. 2013; 793:1-19 [PubMed] Related Publications
The first identified Gadd45 gene, Gadd45a, encodes a ubiquitously expressed protein that is often induced by DNA damage and other stress signals associated with growth arrest and apoptosis. This protein and the other two members of this small gene family, Gadd45b and Gadd45g, have been implicated in a variety of the responses to cell injury including cell cycle checkpoints, apoptosis, and DNA repair. In vivo, many of the prominent roles for the Gadd45 proteins are associated with signaling mediated by p38 mitogen-activated protein kinases (MAPK). Gadd45 proteins can contribute to p38 activation either by activation of upstream kinase(s) or by direct interaction. In vivo, there are important tissue and cell-type-specific differences in the roles for Gadd45 in MAPK signaling. In addition to being p53-regulated, Gadd45a has been found to contribute to p53 activation via p38. Like other stress and signaling proteins, Gadd45 proteins show complex regulation and numerous effectors.

Štorcelová M, Vicián M, Reis R, et al.
Expression of cell cycle regulatory factors hus1, gadd45a, rb1, cdkn2a and mre11a correlates with expression of clock gene per2 in human colorectal carcinoma tissue.
Mol Biol Rep. 2013; 40(11):6351-61 [PubMed] Related Publications
Deregulated expression of clock gene per2 has previously been associated with progression of cancer. The aim of the present study was to identify genes related to per2 expression and involved in cell cycle control. Patients surgically treated for colorectal carcinoma with up-regulated and down-regulated per2 expression in cancer versus adjacent tissue were studied. Total RNA from cancer tissue of these patients was used to specify genes associated with altered per2 expression using the Human Cell Cycle RT(2) profiler PCR array system. We identified seven genes positively correlated (hus1, gadd45α, rb1, cdkn2a, cdk5rp1, mre11a, sumo1) and two genes negatively correlated (cdc20, birc5) with per2 expression. Expression of these seven genes was subsequently measured by real time PCR in all patients of the cohort. Patients were divided into three groups according to TNM classification. We observed an increase in gene expression in cancer tissue compared to adjacent tissue in the first group of patients in all genes measured. Expression of genes positively associated with per2 gene expression was dependent on tumor staging and changes were observed preferentially in cancer tissue. For genes negatively associated with per2 expression we also detected changes in expression dependent on tumor staging. Expression of cdc20 and birc5 was increasing in the proximal tissue and decreasing in the cancer tissue. These results implicate functional involvement of per2 in the process of carcinogenesis via newly uncovered genes. The relevancy of gene expression for determination of diagnosis and prognosis should be considered in relation to tumor staging.

Thurn KT, Thomas S, Raha P, et al.
Histone deacetylase regulation of ATM-mediated DNA damage signaling.
Mol Cancer Ther. 2013; 12(10):2078-87 [PubMed] Free Access to Full Article Related Publications
Ataxia-telangiectasia mutated (ATM) is a major regulator of the DNA damage response. ATM promotes the activation of BRCA1, CHK2, and p53 leading to the induction of response genes such as CDKN1A (p21), GADD45A, and RRM2B that promote cell-cycle arrest and DNA repair. The upregulation of these response genes may contribute to resistance of cancer cells to genotoxic therapies. Here, we show that histone deacetylases (HDAC) play a major role in mitigating the response of the ATM pathway to DNA damage. HDAC inhibition decreased ATM activation and expression, and attenuated the activation of p53 in vitro and in vivo. Select depletion of HDAC1 and HDAC2 was sufficient to modulate ATM activation, reduce GADD45A and RRM2B induction, and increase sensitivity to DNA strand breaks. The regulation of ATM by HDAC enzymes therefore suggests a vital role for HDAC1 and HDAC2 in the DNA damage response, and the potential use of the ATM pathway as a pharmacodynamic marker for combination therapies involving HDAC inhibitors.

Schmidt J, Weijdegård B, Mikkelsen AL, et al.
Differential expression of inflammation-related genes in the ovarian stroma and granulosa cells of PCOS women.
Mol Hum Reprod. 2014; 20(1):49-58 [PubMed] Related Publications
Polycystic ovary syndrome (PCOS) is the most common female endocrine disorder. Ovarian changes in PCOS women are well characterized by ultrasound. However, the ovarian pathophysiology is not fully understood. The aim of this study was to characterize the expression, in both the central ovarian stroma and in granulosa cells (GCs), of a number of genes, including several inflammation-related genes, which have been hypothesized to be involved in the pathophysiology of PCOS. Biopsies of the central ovarian stroma were obtained from PCOS women (Rotterdam criteria) and from normally ovulating women in follicular phase. GCs were retrieved from PCOS-women and non-PCOS women, undergoing in vitro maturation. The expressions of 57 genes were analyzed by quantitative-PCR using a low-density-gene array. The main outcome measures were over-expression or under-expression of the specific genes. The results showed that in the central stroma of PCOS ovaries, five inflammation-related genes (CCL2, IL1R1, IL8, NOS2, TIMP1), the leukocyte marker CD45, the inflammation-related transcription factor RUNX2 and the growth factor AREG were under-expressed. The growth factor DUSP12 and the coagulation factor TFPI2 were over-expressed. In the GC of PCOS, all of the differentially expressed genes were over-expressed; the inflammation-related IL1B, IL8, LIF, NOS2 and PTGS2, the coagulation-related F3 and THBS1, the growth factors BMP6 and DUSP12, the permeability-related AQ3 and the growth-arrest-related GADD45A. In conclusion, the results indicate major alterations in the local ovarian immune system of PCOS ovaries. This may have implications for the PCOS-related defects in the inflammation-like ovulatory process and for the susceptibility to acquire the inflammatory state of ovarian hyperstimulation syndrome.

Jung HJ, Kim HL, Kim YJ, et al.
A novel chemopreventive mechanism of selenomethionine: enhancement of APE1 enzyme activity via a Gadd45a, PCNA and APE1 protein complex that regulates p53-mediated base excision repair.
Oncol Rep. 2013; 30(4):1581-6 [PubMed] Free Access to Full Article Related Publications
Organic selenium compounds have been documented to play a role in cancer prevention. Our previous study showed that selenomethionine (SeMet) induces p53 activation without genotoxic effects including apoptosis and cell cycle arrest. In this study, we investigated the mechanism by which organic selenium compounds promote p53-mediated base excision repair (BER) activity. Our data demonstrated for the first time that the interaction between growth arrest and DNA damage-inducible protein 45A (Gadd45a), which is a p53-activated downstream gene, and two BER-mediated repair proteins, proliferating cell nuclear antigen (PCNA) and apurinic/apyrimidinic endonuclease (APE1/Ref-1), was significantly increased in a p53-dependent manner following treatment with organic selenium compounds. Furthermore, we observed that the activity of APE1 was significantly increased in a p53-dependent manner in response to the organic selenium compounds. These results suggest that BER activity is dependent on wild-type p53 activity and is mediated by the modulation of protein interactions between Gadd45a and repair proteins in response to organic selenium compounds. We propose that p53-dependent BER activity is a distinct chemopreventive mechanism mediated by organic selenium compounds, and that this may provide insight into the development of effective chemopreventive strategies against various oxidative stresses that contribute to a variety of human diseases, particularly cancer.

Takeda S, Nishimura H, Koyachi K, et al.
(-)-Xanthatin induces the prolonged expression of c-Fos through an N-acetyl-L-cysteine (NAC)-sensitive mechanism in human breast cancer MDA-MB-231 cells.
J Toxicol Sci. 2013; 38(4):547-57 [PubMed] Related Publications
We reported that (-)-xanthatin, a xanthanolide sesquiterpene lactone present in the Cocklebur plant, exhibited potent anti-proliferative effects on human breast cancer cells, in which GADD45γ, a novel tumor suppressor gene, was induced. Mechanistically, topoisomerase IIα (Topo IIα) inhibition by (-)-xanthatin was shown to be the upstream trigger that stimulated the expression of GADD45γ mRNA and concomitantly produced reactive oxygen species (ROS) to maintain this expression. Since the anti-cancer drug etoposide, a selective Topo IIα inhibitor, has also been shown to induce intracellular ROS, (-)-xanthatin may exert its anti-proliferative effects on cancer cells in a similar manner to those of etoposide. In the present study, to generalize its applicability to cancer therapy, we further investigated the biological activities of (-)-xanthatin by comparing its activities to those of the established anti-cancer drug etoposide. After the exposure of breast cancer cells to (-)-xanthatin or etoposide, a prolonged and marked up-regulation in the expression of c-fos, a proapoptotic molecule, was detected together with GADD45γ; and the expression of these molecules was stabilized by ROS and abrogated by the pretreatment with N-acetyl-L-cysteine (NAC), a potent ROS scavenger. (-)-Xanthatin in particular exhibited stronger anti-proliferative potential than that of etoposide, which underlies the marked induction of c-fos/GADD45γ and ROS production.

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