title: [Differential gene expression of folylpolyglutamate synthetase in cytoplasm and mitochondria in acquired methotrexate enantiomers resistant to lung cancer A549 cell lines].
abstract: OBJECTIVE
  To investigate the relationship between the resistance of methotrexate (MTX) enantiomer and the gene expression levels of folylpolyglutamate synthetase (FPGS).
  
  
  METHODS
  The cell lines of MTX enantiomer resistance from 15 - 55 µmol/L were obtained when the A549 cell lines were exposed intermittently and progressively to an incremental dose of each MTX enantiomer. The resistant index of MTX resistance cell lines were detected by MTT. The gene expressions of FPGS in cytoplasm and mitochondria were detected by real-time quantitative polymerase chain reaction (PCR).
  
  
  RESULTS
  The resistance indice of D-(-)-MTX resistant cell lines were higher than those of L-(+)-MTX resistant cells (32.7 ± 9.3 vs 11.5 ± 2.9, P < 0.05). The resistant indice of L-(+)-MTX/A549 were from 5 to 15, which mean the middle resistance. The resistant indice of D-(-)-MTX/A549 were more than 15, which mean the severe resistance. The expression of mFPGS had difference between resistant cell lines of L-(+) and D-(-)-MTX except at 15 µmol/L MTX (at 25 µmol/L, 1.3 ± 0.7 vs. 2.3 ± 0.9; at 35 µmol/L, 1.1 ± 0.9 vs. 2.6 ± 0.3; at 45 µmol/L, 1.0 ± 1.0 vs. 1.4 ± 0.8; at 55 µmol/L, 0.2 ± 0.1 vs. 1.0 ± 0.2; all P < 0.05). The expressions of cFPGS had no difference between resistant cell lines of L-(+) and D-(-)-MTX at 15 µmol/L MTX, while at 25 - 55 µmol/L, the cFPGS levels and resistance indice of D-(-)-MTX/A549 resistant cell lines showed a highly negative correlation (r = -0.95, P < 0.05).
  
  
  CONCLUSIONS
  There may be a different mechanism between the first time treatment with 15 µmol/L dosage and the continual treatment with more than 25 µmol/L dosage in A549 cell lines. There had higher resistant index in D-(-)-MTX/A549 cell line than in L-(+)-MTX/A549 cell line. The results indicated that the difference in chirality should be considered in clinical treatment with MTX.
authors.affiliation: Anhui Provincial Center for Clinical Laboratories, Anhui Provincial Hospital, Affiliated Provincial Hospital, Anhui Medical University, Hefei 230001, China.
authors.forename: Hong-Yan
authors.initials: HY
authors.lastname: Zhou
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: He
authors.forename: Yu-Jie
authors.initials: YJ
authors.lastname: Sun
authors.forename: Ren-Zhi
authors.initials: RZ
authors.lastname: Fan
authors.forename: Li
authors.initials: L
authors.lastname: Sun
authors.forename: Zuo-Jun
authors.initials: ZJ
authors.lastname: Shen
mesh_terms: D045744:Cell Line, Tumor; D003593:Cytoplasm / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism; D008727:Methotrexate / Q000494:pharmacology*; D008928:Mitochondria / Q000378:metabolism*; D010453:Peptide Synthases / Q000235:genetics / Q000378:metabolism*
chemical_list: D010453:Peptide Synthases; C023103:folylpolyglutamate synthetase; D008727:Methotrexate