Differential Cytotoxic Effects of Sodium Meta-arsenite on Human Cancer Cells, Dental Papilla Stem Cells and Somatic Cells Correlate with Telomeric Properties and Gene Expression

We investigated the effects of sodium metaarsenite (NaAsO2) on human cancer cells (MDA-MB-231, MCF-7 and U-87 MG), dental papilla tissue stem cells (DPSCs) and somatic cells [MRC-5 fetal fibroblasts and adult muscle cells (MCs)] by examining telomeric properties, endogenous reverse transcriptase (RT) activity and the expression of tumorigenesis-linked genes. Half maximal inhibitory concentration (IC50) values were higher in DPSCs and MCs, possessing longer telomere lengths when compared to cancer cells. Levels of telomerase and RT activity, and the expression of protein 53 (p.53), B-cell lymphoma 2 (BCL2), nuclear factor kappa-light-chain-enhancer of activated B-cells (NF kappa B), transforming growth factor beta (TGF beta) and vascular endothelial growth factor (VEGF) were significantly lower in cancer cells following sodium meta-arsenite treatment, whereas the effect was absent or marginally detected in DPSCs and somatic cells. Collectively, sodium meta-arsenite effectively induced cellular cytotoxicity by inhibiting telomerase and RT activity, and down-regulating transcript levels in cancer cells with shorter telomere lengths, whereas more tolerance was evident in DPSCs and somatic cells possessing longer telotnere lengths.