Mechanisms of Methotrexate Resistance in Acute Leukemia

Görlick, Richard; Cole, Peter D.; Banerjee, Debabrata; Longo, Giuseppe; Li, Weiwei; Hochhauser, Daniel; Bertino, Joseph R.

doi:10.1007/978-1-4615-4811-9_59

Cited by 32 publications

(20 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In ALL the response rate is significantly lower, and the complete responses not as durable (15). Drug resistance is an important cause of relapse in ALL, with multiple molecular mechanisms that vary with the drug and the biologic subtype (33)(34)(35). Because the methylation inhibitor azacytidine prevented the development of HA22 resistance, this combination may prevent resistance in some ALL patients.…”

Section: Discussionmentioning

confidence: 99%

Immunotoxin resistance via reversible methylation of the DPH4 promoter is a unique survival strategy

Wei¹,

Xiang²,

Wayne

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

HA22 is a recombinant immunotoxin composed of an anti-CD22 Fv fused to a portion of Pseudomonas exotoxin A. HA22 produced a high rate of complete remissions in drug-resistant hairy cell leukemia and has a lower response rate in pediatric acute lymphoblastic leukemia (ALL). To understand why patients with ALL have poorer responses, we isolated an ALL cell line that is resistant to killing by HA22. The resistance is unstable; without HA22 the cells revert to HA22 sensitivity in 4 mo. We showed that in the resistant cell line, HA22 is unable to ADP ribosylate and inactivate elongation factor-2 (EF2), owing to a low level of DPH4 mRNA and protein, which prevents diphthamide biosynthesis and renders EF2 refractory to HA22. Analysis of the promoter region of the DPH4 gene shows that the CpG island was hypomethylated in the HA22-sensitive cells, heavily methylated in the resistant cells, and reverted to low methylation in the revertant cells. Our data show that immunotoxin resistance is associated with reversible CpG island methylation and silencing of DPH4 gene transcription. Incubation of sensitive cells with the methylation inhibitor 5-azacytidine prevented the emergence of resistant cells, suggesting that this agent in combination with HA22 may be useful in the treatment of some cases of ALL.DNA methylation | drug resistance | ADP-ribosylation | diphthamide synthesis | epigenetic regulation

show abstract

Section: Discussionmentioning

confidence: 99%

Immunotoxin resistance via reversible methylation of the DPH4 promoter is a unique survival strategy

Wei¹,

Xiang²,

Wayne

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Reduced folate carrier (RFC), folate receptor (FR), and low pH transporters are used for cellular uptake of folate and MTX in mammals (Brzezinska et al 2000). Once inside the cell both folate and MTX are polyglutamated by folylpolyglutamate synthase (FPGS) Rancourt and Walker (1990) b From Jarabak and Bachur (1971) c From Srimatkandada et al (1983) Cytotechnology (2008) 57:1-9 3 (Gorlick et al 1999 Once in the cell, the affinity of DHFR for MTX is much higher than for either folic acid or DHF (Appleman et al 1998) so that the enzyme-bound MTX leads to partial or complete depletion of reduced folate levels and in turn, the inhibition of processes involving folate derivatives. DNA synthesis is compromised when levels of 5,10-CH 2 -THF are reduced as the thymidylate synthase cycle requires this THF derivative to donate a methyl group to dUMP for synthesis of de novo dTMP.…”

Section: Antifolate Inhibition Of Dihydrofolate Reductasementioning

confidence: 99%

A role for Drosophila in understanding drug-induced cytotoxicity and teratogenesis

Affleck

Walker

2008

Cytotechnology

View full text Add to dashboard Cite

Drosophila research has been and continues to be an essential tool for many aspects of biological scientific research and has provided insight into numerous genetic, biochemical, and behavioral processes. As well, due to the remarkable conservation of gene function between Drosophila and humans, and the easy ability to manipulate these genes in a whole organism, Drosophila research has proven critical for studying human disease and the physiological response to chemical reagents. Methotrexate, a widely prescribed pharmaceutical which inhibits dihydrofolate reductase and therefore folate metabolism, is known to cause teratogenic effects in human fetuses. Recently, there has been resurgence in the use of methotrexate for inflammatory diseases and ectopic or unwanted pregnancies thus, increasing the need to fully understand the cytotoxicity of this pharmaceutical. Concerns have been raised over the ethics of studying teratogenic drugs like methotrexate in mammalian systems and thus, we have proposed a Drosophila model. We have shown that exposure of female Drosophila to methotrexate results in progeny with developmental abnormalities. We have also shown that methotrexate exposure changes the abundance of many fundamental cellular transcripts.Expression of a dihydrofolate reductase with a reduced affinity for methotrexate can not only prevent much of the abnormal transcript profile but the teratogenesis seen after drug treatment. In the future, such studies may generate useful tools for mammalian antifolate ''rescue'' therapies.

show abstract

“…inactivating mutations) (7)(8)(9)(10)(11) and quantitative alterations (i.e. decreased or abolished expression) in human RFC (hRFC) gene expression and/or function are documented mechanisms of MTX resistance in acute lymphoblastic leukemia (ALL) (12,13) and osteogenic sarcoma patients (14). Although decreased expression of hRFC mRNA has been suggested as a mechanism of clinical resistance to MTX, the underlying molecular basis is still unknown (12)(13)(14).…”

mentioning

confidence: 99%

Alterations in the Expression of Transcription Factors and the Reduced Folate Carrier as a Novel Mechanism of Antifolate Resistance in Human Leukemia Cells

Rothem¹,

Aronheim²,

Assaraf³

2003

Journal of Biological Chemistry

View full text Add to dashboard Cite

The human reduced folate carrier (hRFC) is the dominant transporter mediating the uptake of reduced folate cofactors and antifolate anticancer drugs. Defective antifolate uptake due to inactivating mutations in the hRFC gene is an established mechanism of drug resistance in various tumor cells. However, while antifolate transport is frequently impaired, either no or only a single hRFC allele is inactivated, suggesting that additional mechanism(s) of resistance are operative. Here we studied the relationship between the expression and function of transcription factors and antifolate resistance in transport-defective leukemia cells that poorly express or completely lack RFC mRNA. Stable transfection with a hRFC expression construct resulted in restoration of normal RFC mRNA expression and nearly wild type drug sensitivity in these antifolate-resistant cells. The loss of RFC gene expression prompted us to explore transcription factor binding to the hRFC promoter. The hRFC promoter contains an upstream GCbox and a downstream cAMP-response element (CRE)/ AP-1-like element. Electrophoretic mobility shift assays and oligonucleotide competition revealed a substantial loss of nuclear factor binding to CRE and GC-box in these drug-resistant cell lines. Consistently, antibodymediated supershift analysis showed a marked decrease in the binding of CRE-binding protein 1 (CREB-1) and specificity protein 1 (Sp1) to CRE and GC-box, respectively. Western blot analysis revealed undetectable expression of CREB-1, decreased ATF-1 levels, parental Sp1 levels, and increased levels of the short Sp3 isoforms, recently shown to repress hRFC gene expression. Transient transfections into these antifolate-resistant cells demonstrated a marked loss of GC-box-dependent, and CRE-driven reporter gene activities and introduction of CREB-1 or Sp1 expression constructs resulted in restoration of hRFC mRNA expression. These results establish a novel mechanism of antifolate resistance that is based on altered expression and function of transcription factors resulting in transcriptional silencing of the hRFC promoter.

show abstract

Mechanisms of Methotrexate Resistance in Acute Leukemia

Cited by 32 publications

References 33 publications

Immunotoxin resistance via reversible methylation of the DPH4 promoter is a unique survival strategy

Immunotoxin resistance via reversible methylation of the DPH4 promoter is a unique survival strategy

A role for Drosophila in understanding drug-induced cytotoxicity and teratogenesis

Alterations in the Expression of Transcription Factors and the Reduced Folate Carrier as a Novel Mechanism of Antifolate Resistance in Human Leukemia Cells

Contact Info

Product

Resources

About