A G316A Polymorphism in the Ornithine Decarboxylase Gene Promoter Modulates MYCN-Driven Childhood Neuroblastoma.
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ABSTRACT:
SUBMITTER: Gamble LD
PROVIDER: S-EPMC8069650 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Neuroblastoma is a pediatric malignancy that arises from the neural crest, and patients with high-risk neuroblastoma, which typically harbor amplifications of MYCN, have an extremely poor prognosis. The tyrosine hydroxylase (TH) promoter-driven TH-MYCN transgenic mouse model faithfully recapitulates many hallmarks of human MYCN-amplified neuroblastoma. A key downstream target of Myc oncoproteins in tumorigenesis is ornithine decarboxylase (Odc), the rate-limiting enzyme of polyamine biosynthesis. Indeed, sustained treatment with the Odc suicide inhibitor alpha-difluoromethylornithine (DFMO) or Odc heterozygosity markedly impairs lymphoma development in Emicro-Myc transgenic mice, and these effects are linked to the induction of the cyclin-dependent kinase (Cdk) inhibitor p27(Kip1), which is normally repressed by Myc. Here, we report that DFMO treatment, but not Odc heterozygosity, impairs MYCN-induced neuroblastoma and that, in this malignancy, transient DFMO treatment is sufficient to confer protection. The selective anticancer effects of DFMO on mouse and human MYCN-amplified neuroblastoma also rely on its ability to disable the proliferative response of Myc, yet in this tumor context, DFMO targets the expression of the p21(Cip1) Cdk inhibitor, which is also suppressed by Myc oncoproteins. These findings suggest that agents, such as DFMO, that target the polyamine pathway may show efficacy in high-risk, MYCN-amplified neuroblastoma.
| S-EPMC2749594 | biostudies-literature
Project description:We have studied the regulation of the expression of ornithine decarboxylase with the aid of transgenic mice harbouring either functional human ornithine decarboxylase genes or the mouse ornithine decarboxylase promoter-driven chloramphenicol acetyltransferase fusion gene in their genome. We used three different stimuli which are well known to enhance ornithine decarboxylase activity in their appropriate target tissues: (i) testosterone in female kidney, (ii) a phorbol ester in epidermis and (iii) partial hepatectomy in liver. Endogenous mouse ornithine decarboxylase activity was strikingly stimulated in response to these treatments. Even though containing the 5' flanking region of the mouse ornithine decarboxylase gene, known to possess full promoter activity, the chloramphenicol acetyltransferase reporter gene was entirely insensitive to any of these stimuli. The human transgene-derived ornithine decarboxylase activity in kidney was unaffected by testosterone treatment, but responded in skin to application of the phorbol ester and likewise was clearly enhanced in regenerating liver. Although mouse endogenous ornithine decarboxylase mRNA levels were distinctly elevated after testosterone, this treatment did not influence the accumulation of the human transgene-derived mRNA. The phorbol ester enhanced the accumulation of mouse endogenous ornithine decarboxylase mRNA and also that derived from the human transgene; however, the enzyme activity was stimulated in regenerating liver without appreciable changes in the levels of endogenous or transgene-derived message. Our present results strongly emphasize the central role of the coding sequence or ornithine decarboxylase gene in the induction of the enzyme activity.
| S-EPMC1134203 | biostudies-other
Project description:BACKGROUND:Dietary arginine and meat consumption are implicated in colorectal cancer (CRC) progression via polyamine-dependent processes. Polymorphism in the polyamine-regulatory gene, ornithine decarboxylase 1 (Odc1, rs2302615) is prognostic for CRC-specific mortality. Here, we examined joint effects of meat consumption and Odc1 polymorphism on CRC-specific mortality. MATERIALS AND METHODS:The analytic cohort was comprised of 329 incident stage I-III CRC cases diagnosed 1994-1996 with follow- up through March 2008. Odc1 genotyping was conducted using primers that amplify a 172-bp fragment containing the polymorphic base at +316. Dietary questionnaires were administered at cohort entry. Multivariate Cox proportional hazards regression analysis for CRC-specific mortality was stratified by tumor, node, metastasis (TNM) stage, and adjusted for clinically relevant variables, plus meat consumption (as a continuous variable, i.e., the number of medium-sized servings/week), Odc1 genotype, and a term representing the meat consumption and Odc1 genotype interaction. The primary outcome was the interaction of Odc1 and meat intake on CRC-specific mortality, as assessed by departures from multiplicative joint effects. RESULTS:Odc1 genotype distribution was 51% GG, 49% GA/AA. In the multivariate model, there was a significant interaction between meat consumption and Odc1 genotype, P-int = 0.01. Among Odc1 GA/AA CRC cases in meat consumption Quartiles 1-3, increased mortality risk was observed when compared to GG cases (adjusted hazards ratio (HR) = 7.06 [95% CI 2.34-21.28]) - a difference not found among cases in the highest dietary meat consumption Quartile 4. CONCLUSIONS:Effects of meat consumption on CRC-specific mortality risk differ based on genetic polymorphism at Odc1. These results provide further evidence that polyamine metabolism and its modulation by dietary factors such as meat may have relevance to CRC outcomes.
| S-EPMC3516190 | biostudies-literature
Project description:Ornithine decarboxylase antizyme 3 (Oaz3) is expressed in spermatids, makes up the antizyme family of Oaz genes with Oaz1 and Oaz2, and was proposed to encode a 22 kDa antizyme protein involved in polyamine regulation similar to the 22 kDa OAZ1 and OAZ2 proteins. Here we demonstrate however that the major product encoded by Oaz3 is a 12 kDa protein, p12, which lacks the antizyme domain that interacts with ornithine decarboxylase. We show that p12 does not affect ornithine decarboxylase levels, providing an explanation for the surprising observation made in Oaz3 knock-out male mice, which do not display altered testis polyamine metabolism. This suggested a novel activity for Oaz3 p12. Using immuno-electron microscopy we localized p12 to two structures in the mammalian sperm tail, viz. the outer dense fibers and fibrous sheath, as well as to the connecting piece linking head and tail. We identified myosin phosphatase targeting subunit 3 (MYPT3), a regulator of protein phosphatase PP1β, as a major p12-interacting protein, and show that MYPT3 is present in sperm tails and that its ankyrin repeat binds p12. We show that MYPT3 can also bind protein phosphatase PP1γ2, the only protein phosphatase present in sperm tails, and that p12- MYPT3 interaction modulates the activity of both PP1β and PP1γ2. This is, to our knowledge, the first demonstration of a novel activity for an Oaz-encoded protein.
| S-EPMC3156769 | biostudies-literature
Project description:Activity of ornithine decarboxylase (ODC), the first enzyme in polyamine synthesis, is required for normal growth and is elevated in many cancers, including colorectal cancer. We examined associations of the +316 ODC1 single nucleotide polymorphism (SNP) with colorectal cancer-specific survival among colorectal cancer cases, and then investigated its functional significance in colon cancer cells.The study included 400 incident stage I-III colorectal cancer cases from the population-based University of California Irvine Gene-Environment Study of Familial Colorectal Cancer (diagnosed from 1994 to 1996 with follow-up through March 2008). The primary outcome was colorectal cancer-specific survival dependent on ODC1 (rs2302615) genotype (GG versus GA/AA). In human colon cancer cell lines, ODC1 allele-specific binding of E-box transcription factors was determined via Western blotting and chromatin immunoprecipitation assays. ODC1 allele-specific promoter activity was determined using promoter constructs in combination with vectors expressing either the transcriptional activator c-MYC or the repressor MAD1.Genotype-specific survival differences were observed among colorectal cancer cases: compared with cases with the ODC1 GG genotype (hazards ratio, 1; reference) the adjusted colorectal cancer-specific survival hazards ratio was 2.02 (95% confidence interval, 1.17-3.50) for ODC1 GA/AA cases (P = 0.012). In colon cancer cells, the ODC1 SNP, flanked by two E-boxes, predicts ODC1 promoter activity. The E-box activator c-MYC and repressors MAD1 and MAD4 preferentially bind to ODC1 minor A-alleles, compared with major G-alleles, in cultured cells.These results have implications for conditional regulation of polyamine homeostasis and suggest a model in which the ODC1 SNP may be protective for colon adenoma recurrence and detrimental for survival after colon cancer diagnosis.
| S-EPMC2769500 | biostudies-literature
Project description:MYCN is a transcription factor that plays key roles in both normal development and cancer. In neuroblastoma, MYCN acts as a major oncogenic driver through pleiotropic effects regulated by multiple protein encoding genes as well as microRNAs (miRNAs). MYCN activity is tightly controlled at the level of transcription and protein stability through various mechanisms. Like most genes, MYCN is further controlled by miRNAs, but the full complement of all miRNAs implicated in this process has not been determined through an unbiased approach. To elucidate the role of miRNAs in regulation of MYCN, we thus explored the MYCN-miRNA interactome to establish miRNAs controlling MYCN expression levels. We combined results from an unbiased and genome-wide high-throughput miRNA target reporter screen with miRNA and mRNA expression data from patients and a murine neuroblastoma progression model. We identified 29 miRNAs targeting MYCN, of which 12 miRNAs are inversely correlated with MYCN expression or activity in neuroblastoma tumor tissue. The majority of MYCN-targeting miRNAs in neuroblastoma showed a decrease in expression during murine MYCN-driven neuroblastoma tumor development. Therefore, we provide evidence that MYCN-targeting miRNAs are preferentially downregulated in MYCN-driven neuroblastoma, suggesting that MYCN negatively controls the expression of these miRNAs, to safeguard its expression.
| S-EPMC4467143 | biostudies-literature
Project description:Ornithine decarboxylase (ODC) is the sentinel enzyme in polyamine biosynthesis. Both ODC and polyamines regulate cell division, proliferation, and apoptosis. Sepiapterin reductase (SPR) catalyzes the last step in the biosynthesis of tetrahydrobiopterin (BH4), an essential cofactor of nitric oxide synthase, and has been implicated in neurological diseases but not yet in cancer. In this study, we present compelling evidence that native ODC and SPR physically interact, and we defined the individual amino acid residues involved in both enzymes using in silico protein-protein docking simulations. The resulting heterocomplex is a surprisingly compact structure, featuring two energetically and structurally equivalent binding modes both in monomer and in dimer conformations. The novel interaction between ODC and SPR proteins was confirmed under physiological conditions by co-immunoprecipitation and co-localization in neuroblastoma (NB) cells. Importantly, we showed that siRNA (small interfering RNA)-mediated knockdown of SPR expression significantly reduced endogenous ODC enzyme activity in NB cells, thus demonstrating the biological relevance of the ODC-SPR interaction. Finally, in a cohort of 88 human NB tumors, we found that high SPR mRNA expression correlated significantly with poor survival prognosis using a Kaplan-Meier analysis (log-rank test, P=5 × 10(-4)), suggesting an oncogenic role for SPR in NB tumorigenesis. In conclusion, we showed that ODC binds SPR and thus propose a new concept in which two well-characterized biochemical pathways converge via the interaction of two enzymes. We identified SPR as a novel regulator of ODC enzyme activity and, based on clinical evidence, present a model in which SPR drives ODC-mediated malignant progression in NB.
| S-EPMC4013099 | biostudies-literature
Project description:One of the greatest barriers to curative treatment of neuroblastoma is its frequent metastatic outgrowth prior to diagnosis, especially in cases driven by amplification of the MYCN oncogene. However, only a limited number of regulatory proteins that contribute to this complex MYCN-mediated process have been elucidated. Here we show that the growth arrest-specific 7 (GAS7) gene, located at chromosome band 17p13.1, is preferentially deleted in high-risk MYCN-driven neuroblastoma. GAS7 expression was also suppressed in MYCN-amplified neuroblastoma lacking 17p deletion. GAS7 deficiency led to accelerated metastasis in both zebrafish and mammalian models of neuroblastoma with overexpression or amplification of MYCN. Analysis of expression profiles and the ultrastructure of zebrafish neuroblastoma tumors with MYCN overexpression identified that GAS7 deficiency led to (i) downregulation of genes involved in cell-cell interaction, (ii) loss of contact among tumor cells as critical determinants of accelerated metastasis, and (iii) increased levels of MYCN protein. These results provide the first genetic evidence that GAS7 depletion is a critical early step in the cascade of events culminating in neuroblastoma metastasis in the context of MYCN overexpression. SIGNIFICANCE: Heterozygous deletion or MYCN-mediated repression of GAS7 in neuroblastoma releases an important brake on tumor cell dispersion and migration to distant sites, providing a novel mechanism underlying tumor metastasis in MYCN-driven neuroblastoma.See related commentary by Menard, p. 2815.
| S-EPMC8178188 | biostudies-literature
Project description:LIN28B has been identified as an oncogene in various tumor entities, including neuroblastoma, a childhood cancer that originates from neural crest-derived cells, and is characterized by amplification of the MYCN oncogene. Recently, elevated LIN28B expression levels were shown to contribute to neuroblastoma tumorigenesis via let-7 dependent de-repression of MYCN. However, additional insight in the regulation of LIN28B in neuroblastoma is lacking. Therefore, we have performed a comprehensive analysis of the regulation of LIN28B in neuroblastoma, with a specific focus on the contribution of miRNAs. We show that MYCN regulates LIN28B expression in neuroblastoma tumors via two distinct parallel mechanisms. First, through an unbiased LIN28B-3'UTR reporter screen, we found that miR-26a-5p and miR-26b-5p regulate LIN28B expression. Next, we demonstrated that MYCN indirectly affects the expression of miR-26a-5p, and hence regulates LIN28B, therefore establishing an MYCN-miR-26a-5p-LIN28B regulatory axis. Second, we provide evidence that MYCN regulates LIN28B expression via interaction with the LIN28B promoter, establishing a direct MYCN-LIN28B regulatory axis. We believe that these findings mark LIN28B as an important effector of the MYCN oncogenic phenotype and underline the importance of MYCN-regulated miRNAs in establishing the MYCN-driven oncogenic process.
| S-EPMC4837470 | biostudies-literature
Project description:Ornithine decarboxylase (ODC) is a significant rate-limiting enzyme in polyamine synthesis, required for normal cell growth, and is highly expressed in various malignancies, including colorectal and breast cancer. In the present study, the associations between the ODC G316A single nucleotide polymorphism (SNP) and breast cancer-specific survival were investigated. In addition, the functional effects of this SNP were examined in the MCF-7 human breast cancer cell line. The present study recruited 300 stage I-III breast cancer cases, which were diagnosed at the Affiliated Cancer Hospital of Zhengzhou University (Zhengzhou, China) between 2002 and 2003, with follow-up visits conducted until May 2013. ODC G316A was genotyped (ODC GG vs. ODC AG/AA) in the 300 cases and the association of the genotypes with cancer-specific survival was analyzed. In the MCF-7 cell line, the ODC allele-specific binding of E-box transcription factors was determined using western blot and chromatin immunoprecipitation assays. Survival differences were observed between the two genotypes: Compared with the ODC GG genotype, patients with ODC GA/AA exhibited significantly higher survival rates (P<0.05). In cultured cells, the ODC SNP, which is flanked by two E-boxes, appeared to predict ODC promoter activity. Furthermore, the E-box activator c-MYC and repressor MAX interactor 1 were found to preferentially bind to ODC minor A-alleles compared with major G-alleles, in cultured MCF-7 cells. In conclusion, the results of the current study suggest that the regulation of ODC may affect survival in breast cancer patients and indicate a model in which the ODC SNP may be protective for breast adenoma recurrence and detrimental for survival following a diagnosis of breast cancer.
| S-EPMC4487138 | biostudies-literature