Capabilities of HPLC with APEX-Q nebulisation ICP-MS and ESI MS/MS to compare selenium uptake and speciation of non-malignant with different B cell lymphoma lines.

Abstract

The formation of intracellular dimethylselenide (DMSe) as a product of exposure of non-malignant (PBMCs) and lymphoma (RL and DHL-4) cell lines to methylseleninic acid (MSA) at clinical levels is suggested here for the first time. This was achieved by analysis of cell lysates by HPLC coupled to ICP-MS via APEX-Q nebulisation, enabling limits of detection for target methyl-Se species which are up to 12-fold lower than those obtained with conventional nebulisation. Methyl-Se-glutathione (CH₃Se-SG), although detected in lysates of cells exposed to MSA, was found to be a reaction product of MSA with glutathione. This was confirmed by HPLC-ESI MS (MS) analysis of lysates of control cells (unexposed to Se) spiked with MSA. The MS/MS data obtained by collision-induced dissociation fragmentation of the ion m/z 402 (for [M+H](+) ⁸⁰Se) were consistent with the presence of CH₃Se-SG. Formation of DMSe was not detected by HPLC-ICP-MS in these spiked lysates, and it was found to require live cells in cell media containing MSA. Interestingly, the ratio of DMSe to CH₃Se-SG was significantly higher in lymphoma cells exposed to MSA in comparison to non-malignant cells. Moreover, maximum Se uptake levels in lymphoma cell lines seemed to be reached much earlier (after 10 min of MSA exposure) than in non-malignant cells. Finally, the GC-TOF-MS speciation data obtained for cell headspace suggested that the major Se species (dimethyldiselenide) appeared to be present in lymphoma cell headspace at significantly higher concentrations than in non-malignant cell headspace after only 10 min of exposure to MSA. Evidence for the presence of dimethylselenidesulfide in lymphoma cell headspace is also provided for the first time.

• Authors: Heidi Goenaga-Infante, Shireen Kassam, Emma Stokes, Christopher Hopley, Simon P Joel
• Journal: Analytical and bioanalytical chemistry (Anal Bioanal Chem) Vol. 399 Issue 5 Pg. 1789-97 (Feb 2011) ISSN: 1618-2650 [Electronic] Germany
• PMID: 21140135 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Organoselenium Compounds
• methylselenic acid
• Selenium
• dimethylselenide

Topics

• Cell Line
• Chromatography, High Pressure Liquid
• Humans
• Lymphoma, B-Cell (chemistry, metabolism)
• Mass Spectrometry
• Organoselenium Compounds (metabolism, pharmacology)
• Selenium (analysis, pharmacokinetics)
• Tissue Distribution