High-performance liquid chromatographic analysis of MTX, 7-OH-MTX and MTX derivatives: application to intracellular metabolism in tumor cells (HT 29)

Methotrexate Polyglutamates Analysis by Chromatography Methods in Biological Matrices: A Review

Methotrexate (MTX) is used as an immunosuppressant and antineoplastic drug in clinical practice. MTX is a parent drug and converts to MTX polyglutamates (MTXPGs) to exhibit its biological activity. Clinical studies found that MTXPG levels were associated with MTX response and toxicities, especially at low doses. Due to huge variance of MTX response and toxicities between individuals, therapeutic drug monitoring is necessary for its use in individualized therapy. Various chromatography methods coupled with ultraviolet-visible detector, fluorescence detector and mass spectrometry have been reported for MTXPG analysis in various biological matrices. The aim of this paper is to review the chromatographic based methods for the measurement of total and/or individual MTXPGs. We searched Embase, Science Direct and PubMed databases using "methotrexate polyglutamate" and "chromatography" as search terms, and found 745 articles. Of those, 14 articles were extracted for this study. The key steps for method development (sample pretreatment, parameter optimization of liquid chromatography and mass spectrometry, selection of internal standard) and validation (lower limit of quantitation, accuracy, precision, recovery, matrix effect and stability) were analyzed and summarized, which might be helpful for researchers to develop their own methods.

Human constitutive androstane receptor mediated methotrexate induction of human dehydroepiandrosterone sulfotransferase (hSULT2A1)

Sulfotransferases (SULTs) catalyzed sulfation is important in the regulation of biological activities of hormones and neurotransmitters, the metabolism of drugs, and the detoxification of xenobiotic toxicants. Sulfation also leads to the bioactivation of procarcinogens. Human dehydroepiandrosterone sulfotransferase (hSULT2A1) is a major SULT catalyzing the sulfation of hydroxysteroids and xenobiotic alcohols. Our previous studies had shown that the anti-folate drug methotrexate (MTX) can up-regulate several major isoforms of human SULTs. To determine the mechanisms controlling the regulation of hSULT2A1, the 5'-flanking region of hSULT2A1 was constructed into the pGL3-Basic luciferase reporter vector. The transcriptional regulation mechanism of hSULT2A1 promoter was studied using Caco-2 cell line based on the reporter gene assay. Nuclear receptor co-transfection results indicated that human constitutive androstane receptor (hCAR) and human retinoid X receptor alpha (hRXRalpha) were involved in the transcriptional regulation of hSULT2A1. RNA interference experiments further proved the role of hCAR in hSULT2A1 regulation. Progressive promoter deletion, DNA sequence alignment, and site directed promoter mutation results suggested that an imperfect inverted repeat DNA motif, IR2 (-186AGCTCAGATGACCC-173), within the hSULT2A1 promoter region mediated the hSULT2A1 induction by MTX. Furthermore, electrophoretic mobility shift assay and super shift assay were employed to characterize the interactions of hCAR and hRXRalpha with the IR2 element. In summary, we identified an IR2 DNA cis-element located at -186/-173 of hSULT2A1 promoter region; the IR2 element mediates the MTX induction of hSULT2A1 through interacting with hCAR and hRXRalpha.

Separation methods for methotrexate, its structural analogues and metabolites

Methotrexate (MTX) is the prototype folate antagonist cytotoxic drug, employed in the therapy of solid tumors and leukaemias, and recently also as an immunosuppressive agent in organ transplantation, in the treatment of some autoimmune diseases and in the therapy of severe asthma. MTX is one of the very few antineoplastic drugs the therapeutic concentration monitoring of which is currently employed in clinical practice and can be routinely measured in biological samples by a number of different analytical techniques, among which are immunoenzymatic and chromatographic methods. Each technique has of course its own advantages in terms of sensitivity, specificity, speed, cost and level of expertise required. Along with therapeutic drug concentration monitoring and clinical pharmacology, fundamental research into the mechanism of action of antifolate drugs is still a field which requires the measurement of MTX, of its new analogues and of their metabolites in biological samples. This review summarizes the instrumental conditions and the performance of several published chromatographic methods employed to measure MTX, its metabolites and some analogues in clinical and biological research. More than 70 papers describing chromatographic assays for MTX and its metabolites have been published in the literature between 1975 and 2000. A wide array of experimental conditions for sample preparation, analyte separation and detection have been employed. According to their chemical properties, MTX, its metabolites and analogue drugs present in several biological samples (plasma, serum, saliva, urine, cerebrospinal fluid, tissue specimens) can be extracted, separated and detected under a variety of chromatographic conditions, i.e. on different stationary phases, under a wide choice of mobile phase conditions (acidic or neutral, employing ion-pair or micellar chromatography), followed by several detection techniques (UV-Vis spectrophotometry, pre- or post-column oxidation and fluorimetry, electrochemistry, mass spectrometry). Optimized methods allow simultaneous measurement within a few minutes of the plasma levels of MTX and its main metabolites at concentrations in the low-nM range. One special field which needs sensitive, fast and inexpensive methods for the detection and measurement of MTX is the monitoring of contamination in workplace environments, such as pharmaceutical industries and oncological hospital pharmacies, and in sewage waters. The measurement of the intracellular gamma-oligo-glutamate metabolites of biological folates, of MTX and of some analogue drugs is of great importance in basic pharmacological research. The existence of empirical quantitative relationships between the retention of individual oligomers under different chromatographic conditions and the number of added glutamic acid units allows identification of the metabolites even when authentic standards are not available.

Simultaneous quantitation of methotrexate and its two main metabolites in biological fluids by a novel solid-phase extraction procedure using high-performance liquid chromatography

We have developed an assay for the simultaneous determination of methotrexate (MTX) and its main metabolites, 7-hydroxymethotrexate (7-OHMTX) and 2,4-diamino-N10-methylpteroic acid (DAMPA) in plasma, urine and saliva meeting the requirement of rapidity for routine use in high-dose MTX therapy and the requirement of sensitivity for its potential use in therapeutic drug monitoring in low-dose MTX therapy. Sample preparation is based on solid-phase extraction using C8 Isolute cartridges. Chromatographic separation was achieved with a reversed-phase column (C18), and quantitation by subsequent exposure to UV light of 254 nm, which converted MTX and its two metabolites by photolytic oxidation to fluorescent products. The recoveries of MTX, 7-OHMTX and DAMPA from plasma at 100 nmol/l were 85.8, 91.1 and 102.3%, respectively. The limits of detection for MTX, 7-OHMTX and DAMPA in plasma and saliva were 0.1 nmol/l. In urine the limit of detection was 10 nmol/l for all compounds. The limits of quantitation in plasma and saliva were 0.5 nmol/l for all compounds.

Production and characterization of highly specific anti-methotrexate monoclonal antibodies

Spleen cells of a Biozzi HR mouse immunized with a bovine serum albumin-methotrexate conjugate were fused with P3-X63-Ag8.653 mouse myeloma cells. Twenty-three monoclonal antibodies (MAbs), selected by indirect ELISA, were produced and partially characterized. Using methotrexate (MTX) and eight structurally related compounds, binding specificities of the MAbs were assessed by inhibition enzyme immunoassay. All the MAbs had very low affinity for folic acid and its analogs and for the major MTX metabolite 7-hydroxymethotrexate. Using a computer cluster analysis program based on the binding specificities, the MAbs were divided into three groups. The thirteen MAbs in group I recognized primarily the pteridine portion of the MTX molecule; the eight group II MAbs recognized the benzene ring as well as the pteridine structure. The two MAbs in group III poorly distinguished between the different parts of the MTX molecule. The apparent equilibrium association constants of the anti-MTX MAbs in groups I, II, and III ranged from 7 x 10(9) to 3 x 10(8) M-1 (except for 1 MAb), from 5 x 10(7) to 6 x 10(6) M-1 (except for 2 MAbs), and from 1 x 10(6) to 3.5 x 10(5) M-1, respectively.