vitamin-b-12 and Fibrosarcoma

Tracking cellular 57Co-labelled cobalamin (57Co-Cbl) uptake is a well-established method for studying Cbl homeostasis. Previous studies established that bovine serum is not generally permissive for cellular Cbl uptake when used as a supplement in cell culture medium, whereas supplementation with human serum promotes cellular Cbl uptake. The underlying reasons for these differences are not fully defined. In the current study we address this question. We extend earlier observations by showing that fetal calf serum inhibits cellular 57Co-Cbl uptake by HT1080 cells (a fibrosarcoma-derived fibroblast cell line). Furthermore, we discovered that a simple heat-treatment protocol (95°C for 10 min) ameliorates this inhibitory activity for HT1080 cell 57Co-Cbl uptake. We provide evidence that the very high level of haptocorrin in bovine serum (as compared to human serum) is responsible for this inhibitory activity. We suggest that bovine haptocorrin competes with cell-derived transcobalamin for Cbl binding, and that cellular Cbl uptake may be minimised in the presence of large amounts of bovine haptocorrin that are present under routine in vitro cell culture conditions. In experiments conducted with AG01518 cells (a neonatal foreskin-derived fibroblast cell line), overall cellular 57Co-Cbl uptake was 86% lower than for HT1080 cells, cellular TC production was below levels detectable by western blotting, and heat treatment of fetal calf serum resulted in only a modest increase in cellular 57Co-Cbl uptake. We recommend a careful assessment of cell culture protocols should be conducted in order to determine the potential benefits that heat-treated bovine serum may provide for in vitro studies of mammalian cell lines.

Topics: Animals; Cattle; Cobalt Radioisotopes; Fetal Blood; Fibrosarcoma; Humans; Transcobalamins; Tumor Cells, Cultured; Vitamin B 12

The cytotoxic effect of cobalamin (vitamin B12) on the growth of malignant and nonmalignant cell lines in culture has been examined. Among the four cobalamins studied, 5'-deoxyadenosylcobalamin, an enzymatically active derivative, was an effective cytotoxic agent. The data indicated that adenosylcobalamin seemed to act selectively on fast-growing malignant cells. Methylcobalamin was also effective at elevated concentrations. Cyanocobalamin was not toxic to all cell lines studied. Hydroxocobalamin at very high concentrations was able to slightly decrease growth of certain cell lines. The results support the hypothesis that the cytotoxic effect of cobalamin was associated with the metabolic activities of this vitamin at the cellular level. Also, cobalamin may be a potential antitumor agent.

Topics: Animals; Blood Cells; Cell Transformation, Neoplastic; Cells, Cultured; Connective Tissue; Connective Tissue Cells; Fibrosarcoma; Humans; Leukemia L1210; Lung; Lymphoma; Male; Mice; Tumor Cells, Cultured; Vitamin B 12

Topics: Animals; Cobalt Isotopes; Fibrosarcoma; Hematinics; Neoplasms; Neuroblastoma; Vitamin B 12

Topics: Abdominal Neoplasms; Antineoplastic Agents; Carcinoma, Hepatocellular; Child; Cyclophosphamide; Female; Fibrosarcoma; Granulosa Cell Tumor; Humans; Infant; Leiomyoma; Liver Neoplasms; Neoplasms; Neuroblastoma; Ovarian Neoplasms; Surgical Procedures, Operative; Teratoma; Vitamin B 12; Wilms Tumor