Effect of several inhibitors of enzymatic DNA methylation on the<i>in vivo</i>methylation of different classes of DNA sequences in a cultured human cell line

Woodcock, David M.; Adams, Jillian; Allan, R. G.; Cooper, Ian

doi:10.1093/nar/11.2.489

Cited by 36 publications

(12 citation statements)

References 21 publications

(27 reference statements)

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“…DNA promoter hypomethylation may cause increased expression of tumor suppression genes (31). 5-Azacytidine causes similar effects, and MTA may also be a DNA methyltransferase inhibitor (31)(32)(33)(34). Direct assay of DNMT catalytic activity indicated no change in an in vitro assay, consistent with the minimal change in global CpG methylation with MTDIA treatment.…”

Section: Discussionmentioning

confidence: 68%

Growth and Metastases of Human Lung Cancer Are Inhibited in Mouse Xenografts by a Transition State Analogue of 5′-Methylthioadenosine Phosphorylase

Basu

Locker

Cassera

et al. 2011

Journal of Biological Chemistry

101

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The S-adenosylmethionine (AdoMet) salvage enzyme 5 -methylthioadenosine phosphorylase (MTAP) has been implicated as both a cancer target and a tumor suppressor. We tested these hypotheses in mouse xenografts of human lung cancers. AdoMet recycling from 5 -methylthioadenosine (MTA) was blocked by inhibition of MTAP with methylthioDADMe-Immucillin-A (MTDIA), an orally available, nontoxic, picomolar transition state analogue. Blood, urine, and tumor levels of MTA increased in response to MTDIA treatment. Disruption of pathways linked to polyamine synthesis and S-adenosylmethionine (AdoMet) 2 salvage provides metabolic targets in anticancer therapy based on the essential roles of these metabolites in cell growth. AdoMet is the major methyl donor for biosynthetic methylation reactions, a precursor for polyamine synthesis, and the source of methyl groups for DNA methylation. Targeting polyamine metabolism directly at L-ornithine decarboxylase by ␣,␣-difluoromethylornithine has had limited anticancer success (1). Two AdoMet molecules are converted to 5Ј-methylthioadenosine (MTA) in spermine synthesis, and 5Ј-methylthioadenosine phosphorylase (MTAP) recycles MTA by phosphorolysis to permit subsequent resynthesis of AdoMet (Fig. 1). Our working hypothesis was that inhibition of MTAP would affect cellular MTA and AdoMet metabolism with downstream effects on protein, DNA methylation, polyamine synthesis, and polyamine-dependent enzyme reactions. We targeted MTAP by transition state analysis and developed methylthio-DADMe-Immucillin-A (MTDIA), an orally available transition state analogue inhibitor of MTAP (2). Others have proposed that MTAP is a tumor suppressor gene (3), and experiments here explore the effects of MTAP inhibition in human lung cancer xenografts.We previously demonstrated that treatment of human FaDu head and neck tumors in mouse xenografts with MT-DIA prevented tumor growth with no apparent toxicity to the mice (4). Here, we report that both MTAP-positive (H358) and MTAP-deleted (A549) human lung cancer cell lines are also sensitive to MTAP inhibition in mouse xenografts. The mechanism is probed by the metabolic and genetic consequences of MTDIA administration. In culture, MTDIA in combination with MTA slows A549 cell growth but induces apoptosis in H358 cells.Lung cancer is the leading cause of cancer-related deaths worldwide (5). Patients diagnosed at an advanced stage have a median survival of less than 12 months (6 -8). Thus, development of novel therapeutics for lung cancer is a research priority. MTDIA demonstrated significant suppression of tumor growth with human lung cancer A549 and H358 cells in mouse xenografts. Low toxicity, oral availability, and significant tumor suppression by MTDIA all support additional evaluation as an agent for the treatment of lung cancers. EXPERIMENTAL PROCEDURESCell Lines-Human non-small cell lung adenocarcinoma (NSCLC) cell line A549 and prostate carcinoma cell line PC3 were obtained from the American Type Culture Collection (Manassas, VA). Human bronchioloalveolar ...

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Section: Discussionmentioning

confidence: 68%

Growth and Metastases of Human Lung Cancer Are Inhibited in Mouse Xenografts by a Transition State Analogue of 5′-Methylthioadenosine Phosphorylase

Basu

Locker

Cassera

et al. 2011

Journal of Biological Chemistry

101

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“…These enzymes recognize hemimethylated DNA resulting from DNA replication, and add the appropriate methyl groups on the newly synthesized strand (13). The possibility that different maintenance methylases could be simultaneously active was suggested by Woodcock et al (24,25). In a mammalian cell line, a minor but consistent fraction of DNA showed methylation that was delayed from DNA synthesis by several hours.…”

Section: Discussionmentioning

confidence: 99%

DNA synthesis, methylation and degradation during conjugation inTetrahymena thermophila

Harrison

Karrer

1985

Nucl Acids Res

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We have investigated the timing of DNA synthesis, methylation and degradation during macronuclear development in the ciliate, Tetrahymena thermophila. DNA synthesis was first detected in the anlagen early in macronuclear development, but the majority of DNA synthesis occurred later, after pair separation. Anlagen DNA was first detectably methylated at GATC sites 3-5 hours after its synthesis. Once initiated, de novo methylation was rapid and complete, occurring between 13.5 and 15 hours of conjugation. The level of methylation of GATC sites was constant throughout the remainder of conjugation, and was similar to that in mock-conjugated cells. Degradation of DNA in the old macronucleus and DNA synthesis in the anlagen began at about the same time. Upon pair separation, less than 20% of old macronuclear DNA remained. A small percentage of nucleotides prelabeled prior to conjugation were recycled in the developing anlagen.

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“…dcAdoMet is an inhibitor of methylation reactions, such as DNA methylation (73, 86), as this compound cannot donate its methyl group. MTA is both an inhibitor of methylation reactions (54, 119, 264) and an inhibitor of AHCY (208). AHCY, as mentioned in section III A , is a reversible enzyme that cleaves AdoHcy, a potent inhibitor of methylation reactions, into adenosine and Hcy.…”

Section: Metabolism Of Adometmentioning

confidence: 99%

S-adenosylmethionine in Liver Health, Injury, and Cancer

Mato²

2012

Physiological Reviews

439

593

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S-adenosylmethionine (AdoMet, also known as SAM and SAMe) is the principal biological methyl donor synthesized in all mammalian cells but most abundantly in the liver. Biosynthesis of AdoMet requires the enzyme methionine adenosyltransferase (MAT). In mammals, two genes, MAT1A that is largely expressed by normal liver and MAT2A that is expressed by all extrahepatic tissues, encode MAT. Patients with chronic liver disease have reduced MAT activity and AdoMet levels. Mice lacking Mat1a have reduced hepatic AdoMet levels and develop oxidative stress, steatohepatitis, and hepatocellular carcinoma (HCC). In these mice, several signaling pathways are abnormal that can contribute to HCC formation. However, injury and HCC also occur if hepatic AdoMet level is excessive chronically. This can result from inactive mutation of the enzyme glycine N-methyltransferase (GNMT). Children with GNMT mutation have elevated liver transaminases, and Gnmt knockout mice develop liver injury, fibrosis, and HCC. Thus a normal hepatic AdoMet level is necessary to maintain liver health and prevent injury and HCC. AdoMet is effective in cholestasis of pregnancy, and its role in other human liver diseases remains to be better defined. In experimental models, it is effective as a chemopreventive agent in HCC and perhaps other forms of cancer as well.

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Effect of several inhibitors of enzymatic DNA methylation on thein vivomethylation of different classes of DNA sequences in a cultured human cell line

Cited by 36 publications

References 21 publications

Growth and Metastases of Human Lung Cancer Are Inhibited in Mouse Xenografts by a Transition State Analogue of 5′-Methylthioadenosine Phosphorylase

Growth and Metastases of Human Lung Cancer Are Inhibited in Mouse Xenografts by a Transition State Analogue of 5′-Methylthioadenosine Phosphorylase

DNA synthesis, methylation and degradation during conjugation inTetrahymena thermophila

S-adenosylmethionine in Liver Health, Injury, and Cancer

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