Mandal S, Richardson VJ, Banoub J, Church JG. Identification of myo-inositol 1,2-cyclic monophosphate by electrospray tandem mass spectrometry, a major constituent of EGF-stimulated phosphoinositide turnover in MDA 468 cells.
Exp Cell Res 2002;
277:131-8. [PMID:
12083795 DOI:
10.1006/excr.2002.5549]
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Abstract
Epidermal growth factor (EGF) caused an increase in phosphoinositide (PI) turnover in MDA 468 cells. This EGF-stimulated effect was inhibited by the protein tyrosine kinase inhibitor lavendustin A (LA). MDA 468 cells generated an atypical PI turnover profile. Examination and quantitation of the PI metabolite profile showed that even control cells produced a metabolite which was acid-labile and which formed about 60% of the total PI metabolites. By using the technique of electrospray ionization tandem mass spectrometry, we were able to confirm the identity of this acid-labile metabolite through the specific fragmentation as compared with the standard. The precursor molecule fragmented into two distinct productions with molar masses identical to that of the standard myo-inositol 1,2-cyclic monophosphate (cInsP). Changes in the PI turnover profile could be accounted for by the alterations in myo-inositol 1,2-cyclic monophosphate generated in these cells. We thus conclude that, by some as-yet-unidentified mechanism, cyclic inositol monophosphate forms a major constituent of EGF-stimulated PI turnover in MDA 468 cells.
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