Gene expression profiling of leukemia T-cells resistant to methotrexate and 7-hydroxymethotrexate reveals alterations that preserve intracellular levels of folate and nucleotide biosynthesis

Abstract

International audiencetreatment of human T-cell leukemia cells with 7-hydroxymethotrexate, the major metabolite of methotrexate resulted in acquired resistance as a result of the complete loss of folypolyglutamate synthetase (FPGS) activity. This was in contradistinction to the major modality of antifolate resistance of impaired drug transport in leukemia cells exposed to methotrexate.. To identify the genes associated with methotrexate and 7-hydroxymethotrexate resistance, we herein explored the patterns of genome-wide expression profiles in these antifolte-resistant leukemia sublines. mRNA levels of the reduced folate carrier, the primary influx transporter of folates and antifolates, were down-regulated >2-fold in methotrexate -resistant cells. The dramatic loss of FPGS activity in 7-hydroxymethotrexate - resistant cells was associated with alterations in the expression of various genes aimed at preserving reduced folates and/or enhancing purine nucleotide biosynthesis e.g. methylene tetrahydrofolate reductase, glycinamide ribonucleotide formyltransferase, adenosine deaminase, cystathionine β synthase, as well as the ATP-dependent folate exporters / and /. The observed changes in gene expression were generally not paralleled by acquired DNA copy numbers alterations, suggesting transcriptional regulatory mechanisms. Interestingly, gene expression of DNA/RNA metabolism and transport genes were more profoundly altered in methotrexate -resistant subline, whereas in 7-hydroxymethotrexate -resistant cells, the most profoundly affected groups of genes were those encoding for proteins involved in metabolism and cellular proliferation. Thus, the present investigation provides evidence that 7-hydroxymethotrexate induces gene expression alterations and an antifolate resistance modality that are distinct from its parent drug methotrexate

Polymorphisms in folate-related genes: impact on risk of adult acute lymphoblastic leukemia rather than pediatric in Han Chinese

“…ABCG2 is a member of the ABC transporter family and has the activity to transport folates and antifolates (Figure 1). The ABCG2 421G 4 T variant causes a lower protein expression level [31], which results in a decrease of folate efflux and leads to the expansion of the intracellular folate pool both in vitro and in vivo [32][33][34]. Therefore, the mechanism of the reduction of risk of ALL by the ABCG2 421G 4 T variant may be due to the increased intracellular level of folate.…”

Single agent and combination studies of pralatrexate and molecular correlates of sensitivity

“…Pralatrexate acquired resistance was associated with decreased RFC-1 expression and increased MDR1 expression. Fotoohi et al (2009) described antifolate-resistant leukaemia lines with mRNA levels of RFC-1 downregulated more than two-fold in methotrexate-resistant cells, emphasizing the important role of inux transport in antifolate resistance. Similar data were previously obtained by Jansen and Pieters (1998), Rothem et al (2004), and Ifergan et al (2003) using other methotrexate-resistant cellular models.…”

MJ-29 Inhibits Tubulin Polymerization, Induces Mitotic Arrest, and Triggers Apoptosis via Cyclin-Dependent Kinase 1-Mediated Bcl-2 Phosphorylation in Human Leukemia U937 Cells

“…Approximately 3.8 of every 100,000 people die each year of leukemia, and it is the 12th most common malignancy in Taiwan based on a report from the Department of Health, Executive Yuan of Taiwan in 2008 (Department of Health, Taiwan, http://www.doh.gov.tw/EN2006/ index_EN.aspx). In the clinical therapy of leukemia patients, bone marrow transplant, radiotherapy, and chemotherapy are applied (Nau and Lewis, 2008;Fotoohi et al, 2009). Microtubule-targeting agents (MTAs) are primarily used, and they are the most effective drugs in leukemia treatment (Perez, 2009).…”