Sodium ascorbate potentiates the growth inhibitory effect of certain agents on neuroblastoma cells in culture.

Abstract

Mouse neuroblastoma (NB) cells in culture were more sensitive to sodium L-ascorbate than were rat glioma cells by the criterion of growth inhibition (due to cell death and reduction in cell division). Sodium L-ascorbate at nonlethal concentrations potentiated the effect of 5-fluorouracil (FUra), x-irradiation, bleomycin, R020-1724, prostaglandin El, and sodium butyrate on NB cells but did not produce such an effect on glioma cells. Sodium L-ascorbate did not enhance the effect of vincristine, 6-thioguanine, or 1-2-chloroethyl--cyclohexyl-1-nitrosourea (CCNU) except at higher drug doses and it reduced the cytotoxic effect of methotrexate and 5-3,3-dimethyl-1-triazeno)imidazole4-carboxamide (DTIC) on NB cells. Sodium D-ascorbate produced effects similar to those produced by sodium L-asco ate on NB cells. L-Ascorbic acid-2-sulfate (barium salt) affected neither the growth rate nor the effect of 5-FUra on NB cells. Glutathione, a reducing agent, was more toxic to NB cells in comparison to D-or L-ascorbate; however, at a similar concentration it failed to potentiate the effect of 5-FUra on NB cells.The beneficial effect of high doses of ascorbic acid in advanced human neoplasms has been reported (1-3). Because of its potential significance as a chemotherapeutic agent, the effects of sodium ascorbate in combination with some tumor therapeutic agents were studied to ascertain if sodium ascorbate would potentiate their growth inhibitory effect (due to cell death and reduction of cell division). We report that sodium ascorbate at nonlethal concentrations potentiates the growth inhibitory effect of 5-fluorouracil (5-FUra), bleomycin sulfate, sodium butyrate, cyclic AMP stimulating agents, and x-irradiation on neuroblastoma (NB) cells, but it does not produce a similar effect on rat glioma cells in culture. MATERIALS AND METHODSThe procedures for culturing and maintaining mouse neuroblastoma (NBP2) cells have been described (4). Rat glioma (C-6, passage number 24-38) cells developed by Benda et al. (5), were maintained in Eagle's minimal essential medium containing 10% fetal calf serum, penicillin (100 units/ml), and streptomycin (100 ,g/ml). Mouse fibroblasts (L cells) were grown under conditions described for NB cells. L-Ascorbic acid (Sigma) or D-isoascorbic acid (Sigma) was dissolved in water at a concentration of 10 mg/ml and the pH was adjusted to 7.0 with sodium hydroxide. Sodium ascorbate in solution is unstable (6, 7) and light sensitive; therefore, a fresh solution was made every week, and the vials were wrapped with aluminum foil to protect the solution against light. Beef liver catalase suspended in 0.1% thymol (Sigma) was diluted with water at a concentration of 5 mg/ml. The concentration of the original stock solution was 50 mg/ml (33,300 units/ml). One unit decomposes 1 umol of hydrogen peroxide per min at pH 7.0 at 250C. 5-FUra, 5-(3,3-dimethyl-btriazeno)-imidazole-4-carboxamide (DTIC), 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), bleomycin sulfate, adriamycin sulfate, 6-thioguanine, vincris...

Mobilization of iron from cellular ferritin by ascorbic acid in neuroblastoma SK‐N‐SH cells: an EPR study

“…Since neuroblastoma cells contain elevated iron levels (stored in ferritin) and produce high amounts of H202 [26,30], conditions for pro-oxidative cell injury can be generated by application of ascorbic acid. This may open new ways in cancer therapy of this hardly curable tumor in stage IV, especially in combination with some cytostatic drugs [24].…”

“…Ascorbate is particularily interesting because of its hypothesized pro-oxidative activity in neuroblastoma tissue originating from the potentiating effect of ascorbate on commonly used antitumourigenic agents like fluorouracil or bleomycin [24]. Further work demonstrated that ascorbic acid induces DNA strand breaks in neuroblastoma cells [25,26] and tissues [27].…”

The enhanced tumor inhibitory effects of gefitinib and L-ascorbic acid combination therapy in non-small cell lung cancer cells

“…The increase in intracellular ROS production induced by imatinib mesylate in patients with CML causes genetic instability and gene mutations, leading to mutation of the kinase domain and subsequent drug resistance. Antioxidants may decrease the levels of ROS present in cells and, therefore, decrease the risk of gene mutations and associated drug resistance (32).…”

Morphology and DNA degeneration during autoschizic cell death in bladder carcinoma T24 cells induced by ascorbate and menadione treatment

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