Titanates Deliver Metal Compounds to Suppress Cell Metabolism

BackgroundTitanates are inorganic, amorphous, aqueously insoluble, particulate compounds of titanium, oxygen, hydrogen, and sodium. Two types of titanates, monosodium titanate (MST) and amorphous peroxotitanate (APT), have recently been proposed for use in biological applications where it would be advantageous to locally sequester and deliver metals to alter cellular functions.PurposeIn the current study, the ability of MST and APT to suppress the mitochondrial function of a rapidly dividing cell line, OSC2 (oral squamous cell carcinoma) with and without loaded metals [Au(III), Hg(II), Pd(II), Pt(II), Pt(IV), and cisPt] was determined.MethodsCellular mitochondrial activity of OSC2 cells after 72 hours exposure to titanates or titanate-metal compounds was estimated by measuring succinate dehydrogenase (SDH) activity via the 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method.ResultsThe results of this study showed that neither native APT nor native MST was biologically neutral to oral squamous cell carcinoma (OSC2). Increasing the concentration of either MST or APT resulted in a statistically significant decrease in SDH activity of OSC2 cells versus untreated cells (40% for APT and 30% for MST). The addition of titanate-metal compounds augmented the effects of APT and MST on OSC2 metabolism, decreasing overall mitochondrial activity compared to controls by 50–70%. However, both titanate types and metal ion species determined the degree to which the SDH activity was suppressed.ConclusionThe findings of the current study demonstrate that APT and MST alone significantly suppress the metabolism of a rapidly dividing cell line, an effect that is augmented by specific titanate-metal combinations. These compounds may have potential as unique therapeutic agents.