5-6-7-8-tetrahydrofolic-acid and Colonic-Neoplasms

Leucovorin is commonly used as folate supplement in 5-fluorouracil-based chemotherapy, but needs to be converted to active 5,10-methylenetetrahydrofolate (methyleneTHF) intracellularly. This provides for interindividual differences. MethyleneTHF has recently been developed into the stable, distributable drug, Modufolin®. The aim was to compare the concentration of folate metabolites in tumor, mucosa, and plasma of patients with colon cancer after administration of Modufolin® or Isovorin® (levo-leucovorin).. Thirty-two patients scheduled for colon resection were randomized to receive Modufolin® or Isovorin® at dosage of 60 or 200 mg/m². The study drug was given as one i.v. bolus injection after anesthesia. Plasma was collected for pharmacokinetic (PK) analysis before, during, and after surgery. Tissue biopsies were collected at surgery. Folate metabolites were analyzed by LC-MS/MS.. MethyleneTHF and THF concentrations were significantly higher in mucosa (p < 0.01, both dosages) and tumors (p < 0.01, 200 mg/m²) after Modufolin® as compared to Isovorin® administration. The results correlated with PK observations. The Modufolin® to Isovorin® C(max) ratio for methyleneTHF was 113 at 200 mg/m² and 52 at 60 mg/m²; the AUC(last) ratios were 17 and 9, respectively. The THF plasma concentrations were also higher after Modufolin® administration (C(max) ratio 23, AUC(last) ratio 13 at 200 mg/m²; C(max) ratio 15, AUC(last) ratio 11 at 60 mg/m²).. Modufolin® administration resulted in significantly higher methyleneTHF levels than Isovorin® and may potentially increase the efficacy of 5-fluorouracil-based chemotherapy. The results encourage further evaluation of Modufolin® as a substitute to Isovorin® including the potential clinical benefits.

Topics: Adult; Aged; Aged, 80 and over; Antidotes; Antimetabolites, Antineoplastic; Biotransformation; Colonic Neoplasms; Combined Modality Therapy; Dose-Response Relationship, Drug; Female; Fluorouracil; Humans; Injections, Intravenous; Intestinal Mucosa; Levoleucovorin; Male; Middle Aged; Perioperative Period; Prodrugs; Single-Blind Method; Tetrahydrofolates; Tissue Distribution

The folate antagonist methotrexate (MTX) inhibits synthesis of tetrahydrofolate (THF), pyrimidines and purines, and induces differentiation in several cell types. At 1 microM, MTX reduced proliferation and induced differentiation in HT29 colon cancer cells; the latter effect was augmented (P < 0.001) by thymidine (100 microM) but was reversed (P < 0.001) by the purines, hypoxanthine (Hx; 100 microM) and adenosine (100 microM). In contrast 5-fluoro-uracil (5-FU), a specific thymidylate synthase (TS) inhibitor, had no effect on differentiation, suggesting that MTX-induced differentiation is not due to a reduction in thymidine but to the inhibition of purine biosynthesis. Inhibition of cyclic AMP (cAMP) by RpcAMP (25 microM) further enhanced (P < 0.001) MTX induced differentiation, whereas the cAMP activator forskolin (10 microM) reversed (P < 0.001) MTX induced differentiation. These observations implicate a central role of adenosine and cAMP in MTX induced differentiation. By combining Western blot analysis with liquid chromatography-mass spectrometry (LC-MS)and HPLC analyses we also reveal both the expression and activity of key enzymes (i.e. methionine synthase (MS), s-adenosylhomocysteinase, cystathionine beta-synthase and ornithine decarboxylase) regulating methyl cycle, transsulfuration and polyamine pathways in HT29 colon cancer cells. At 1 microM, MTX induced differentiation was associated with a marked reduction in the intracellular concentrations of adenosine and, consequently, S-adenosylmethionine (SAM), S-adenosylhomocysteine, polyamines and glutathione (GSH). Importantly, the marked reduction in methionine that accompanied MS inhibition following MTX treatment was non-limiting with respect to SAM synthesis. Collectively, these findings indicate that the effects of MTX on cellular differentiation and single carbon metabolism are primarily due to the intracellular depletion of purines.

Topics: Adenocarcinoma; Adenosine; Alkaline Phosphatase; Antimetabolites, Antineoplastic; Cell Differentiation; Cell Proliferation; Colonic Neoplasms; Cyclic AMP; Extracellular Signal-Regulated MAP Kinases; HT29 Cells; Humans; Hypoxanthines; MAP Kinase Kinase Kinases; Methionine; Methotrexate; Phosphatidylinositol 3-Kinases; Polyamines; Purines; Signal Transduction; Tetrahydrofolates; Thymidine

The insulin-like growth factor-I receptor (IGF-IR) has an important role in colorectal cancer development and progression. IGF-IR displays a potent anti-apoptotic activity and is overexpressed in primary tumors and colon cancer-derived cell lines. Folic acid, a member of the vitamin B family, is a chemopreventive agent whose deficiency has been linked to an enhanced colon cancer risk. The present study was aimed at testing the hypothesis that part of the modulatory effect of folic acid on malignant transformation may be attributed to its ability to regulate IGF-IR gene expression. Regulation of IGF-IR gene expression by folic acid was assessed using western blots, RT-PCR, transient transfections and chromatin immunoprecipitation assays. Activation of the IGF-IR signaling pathway was evaluated by measuring phosphorylation of ERK, and apoptosis was assayed using poly (ADP-ribose) polymerase cleavage and annexin V-FITC staining. Results obtained showed that folic acid induced a dose-dependent decrease in IGF-IR protein and mRNA levels in the HCT116 +/+ colon cancer cell line. This effect was associated with a significant reduction in IGF-IR promoter activity. Similar effects were elicited by the folic acid metabolites dihydrofolic acid and tetrahydrofolic acid. In addition, folic acid abrogated the IGF-I-stimulated phosphorylation of the downstream signaling molecule ERK1/2 and exhibited a pro-apoptotic activity. Moreover, folic acid induced a significant decrease in Sp1 binding to the IGF-IR promoter region. Finally, folic acid had no effect in wild-type p53-depleted HCT116 -/- and Caco-2 cells. In conclusion, the mechanism of action of folic acid involves regulation of IGF-IR gene expression. The ability of folic acid to downregulate the IGF-I signal transduction pathway may allow the micronutrient to function as a chemopreventive agent. Folic acid deficiency, on the other hand, may lead to increased IGF-IR gene expression, with ensuing pathological activation by endocrine and/or autocrine/paracrine IGF-I.

Topics: Apoptosis; Colonic Neoplasms; Down-Regulation; Folic Acid; Gene Expression; Gene Expression Regulation, Neoplastic; Humans; Promoter Regions, Genetic; Receptor, IGF Type 1; Tetrahydrofolates; Tumor Cells, Cultured; Tumor Suppressor Protein p53

Currently, biochemical modulation for 5-fluorouracil (5-FU) is one of the most successful chemotherapy for both colo-rectal and gastric cancer. The purpose of this study is to evaluate the significance of measuring intratumoral thymidylate synthetase (TS) and folate (FH4) levels as predictive parameters for the successful treatment. Samples were collected from 16 advanced colo-rectal and 21 advanced gastric cancer. TS and tetrahydrofolate levels in the specimens were measured by binding assay. Results showed that there were no significant difference in TS levels between the different pathologic types of carcinoma. On the other hand, well (3.94 +/- 1.75 p mol/g) and moderately (5.95 +/- 2.69 p mol/g) differentiated carcinoma showed lower FH4 levels compared to poorly differentiated carcinoma (9.58 +/- 5.27 p mol/g). In conclusion, biochemical modulation by cisplatin or leucovorin, which elevates intratumoral folate levels, is more needed for well and moderately differentiated carcinoma. Finally, measuring TS levels can also be important because two cases who responded to cisplatin/5-FU chemotherapy showed low TS levels compared to the others who had lower response.

Topics: Adenocarcinoma; Antineoplastic Combined Chemotherapy Protocols; Cisplatin; Colonic Neoplasms; Fluorouracil; Humans; Stomach Neoplasms; Tetrahydrofolates; Thymidylate Synthase