Methotrexate in Pediatric Osteosarcoma: Response and Toxicity in Relation to Genetic Polymorphisms and Dihydrofolate Reductase and Reduced Folate Carrier 1 Expression

Abstract

ObjectiveTo determine the influence of the genotype and the level of expression of different enzymes involved in folate metabolism on the response to and toxicity of high-dose methotrexate treatment in pediatric osteosarcomas. Study designDHFR and Reduced folate carrier 1 (RFC1) semiquantitative expression was analyzed in 34 primary and metastatic osteosarcoma tissues by real-time polymerase chain reaction. The following polymorphisms were also analyzed in peripheral blood from 96 children with osteosarcoma and 110 control subjects: C677T, A1298C (MTHFR), G80A (RFC1), A2756G (MTR), C1420T (SHMT), the 28bp-repeat polymorphism, and 1494del6 of the TYMS gene. Treatment toxicity was scored after each cycle according to criteria from the World Health Organization. ResultsDHFR and RFC1 expression was lower in initial osteosarcoma biopsy specimens than in metastases (P = .024 and P = .041, respectively). RFC1 expression was moderately decreased in samples with poor histologic response to preoperative treatment (P = .053). Patients with osteosarcoma with G3/G4 hematologic toxicity were more frequently TT than CT/CC for C677T/MTHFR (P = .023) and GG for A2756G/MTR (P = .048 and P = .057 for gastrointestinal and hematologic toxicity, respectively). ConclusionsThe role of C677T/MTHFR and A2756G/MTR on chemotherapy-induced toxicity should be further investigated in pediatric osteosarcomas receiving high-dose methotrexate. Altered expression of DHFR and RFC1 is a feasible mechanism by which osteosarcoma cells become resistant to methotrexate.

Methotrexate ameliorates pristane-induced arthritis by decreasing IFN-γ and IL-17A expressions

“…Thus, it mainly prevents de novo pyrimidine and purine syntheses (Celtikci et al, 2009;Patiño-García et al, 2009;Shimura et al, 2009). It has been reported that MTX efficiently suppresses PIA when given after the onset of arthritis, but the mechanism remains obscure (Lange et al, 2005).…”

Influence of Reduced Folate Carrier and Dihydrofolate Reductase Genes on Methotrexate-Induced Cytotoxicity

“…In the pediatric osteosarcomas, it was proposed that impaired intracellular transport of MTX by decreased RFC levels is the most feasible mechanism of acquired resistance (17,18).…”

Germline genetic polymorphisms may influence chemotherapy response and disease outcome in osteosarcoma

“…2,3,6,[13][14][15][16] In osteosarcoma, MTHFR c.677C>T p.Ala 222 Val increased hematological toxicity but did not influence survival. 17 Cisplatin and doxorubicin form helix-distorting DNA adducts resulting in strand breakage and inhibition of replication. Restoration of damaged DNA is by nucleotide excision repair (NER), whereas glutathione-S-transferase (GST) enzymes play a detoxification role.…”