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.
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.
Mandal
Soma
S
Terry Fox Cancer Research Laboratories, Memorial University of Newfoundland, St. John's, Canada A1B 3V6.
Richardson
Vernon J
VJ
Banoub
Joseph
J
Church
Jon G
JG
D000143:Acids; D001943:Breast Neoplasms; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005260:Female; D006801:Humans; D006868:Hydrolysis; D007295:Inositol Phosphates / Q000302:isolation & purification / Q000378:metabolism*; D010636:Phenols / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011960:Receptors, Estrogen; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D014407:Tumor Cells, Cultured
D000143:Acids; D007295:Inositol Phosphates; D010636:Phenols; D010716:Phosphatidylinositols; D011960:Receptors, Estrogen; C462759:myo-inositol 1,2-cyclic monophosphate; C062898:lavendustin A; D004815:Epidermal Growth Factor; D011505:Protein-Tyrosine Kinases