Cytotoxic effect of menadione and sodium orthovanadate in combination on human glioma cells

Abstract

Gliomas are the most common primary brain tumor, and their treatment is still a challenge. Here, we evaluated the antiproliferative effect of a novel combination of two potent oxidative stress enhancers: menadione (M) and sodium orthovanadate (SO). We observed both short-term and prolonged growth inhibitory effects of M or SO alone as well as in combination (M:SO) on DBTRG.05MG human glioma cells. A stronger antiproliferative effect was observed in the short-term proliferation assay with the M:SO combination compared to either investigated agent alone. In the long-term proliferation assay, a 10-day exposure to M:SO at concentrations of 10 μM:17.5 μM or 17.5 μM:10 μM was enough to kill 100% of the cells; no cell regrowth was observed after re-incubation in drug-free media. When used in combination, the single concentration of M and SO could be decreased by 2.5- to 5-fold of those used for each experimental drug alone and still obtain a similar antiproliferative effect. The underlying molecular mechanism was investigated by co-incubating M:SO with dithiothreitol (DTT) and genistein. Both substances partially neutralized the effects of the M:SO combination, showing additive effects. This observation suggests a role of oxidative stress and tyrosine kinase stimulation in the M:SO cytotoxic effect. Our results indicate that M:SO combination is an attractive alternative for glioma treatment that encourages further study. The neutralizing effects of genistein and DTT reveal a possibility for their use in the minimization of potential M:SO systemic toxicity.

Menadione : Sodium Orthovanadate Combination Eliminates and Inhibits Migration of Detached Cancer Cells

“…In gliomas, the “complex system model” [19] and “the stemness phenotype model” [20] predicted that in order to completely eradicate glioma all cancer cell types (stem and nonstem cancer cells) should be eliminated at once since the targeting of only one population, for example, cancer stem cells, will unlikely be a successful strategy [21]. If this prediction is true and a similar situation occurs in other types of cancer, a successful treatment will require the use of pankiller drugs, defined by us as a drug or combination of drugs that eliminates 100% of cancer cells in vitro preventing regrowth when the drug is removed [22, 23]. The prefix “pan” comes from the ancient Greek word παν - pan- (all, every).…”

“…For this purpose, we recently introduced a proliferation assay where cells are subjected to prolonged (between 7 and 14 days) drug exposure [22–24]. This assay has the potential to detect around 0.01% of resistant cells and is technically easy to perform compared to the clonogenic assay [22] that gives similar information.…”

“…For this purpose, we recently introduced a proliferation assay where cells are subjected to prolonged (between 7 and 14 days) drug exposure [22–24]. This assay has the potential to detect around 0.01% of resistant cells and is technically easy to perform compared to the clonogenic assay [22] that gives similar information. Using this long-term assay we have reported that combinations of menadione : vitamin C (M : VC) and menadione : sodium orthovanadate (M : SO) have pankiller activity against a panel of glioma cell lines [22, 23].…”

“…This assay has the potential to detect around 0.01% of resistant cells and is technically easy to perform compared to the clonogenic assay [22] that gives similar information. Using this long-term assay we have reported that combinations of menadione : vitamin C (M : VC) and menadione : sodium orthovanadate (M : SO) have pankiller activity against a panel of glioma cell lines [22, 23]. Menadione alone or in combination with vitamin C has shown anticancer activity likely by its ability to generate oxidative stress and ultimately induce cell death [28–30].…”

“…Menadione alone or in combination with vitamin C has shown anticancer activity likely by its ability to generate oxidative stress and ultimately induce cell death [28–30]. We previously showed in human glioma cells that the M : SO combination exerts cytotoxic effects likely via the generation of oxidative stress and tyrosine kinase stimulation [22]. Sodium orthovanadate is a tyrosine phosphatase inhibitor [31].…”