Bioorganic & Medicinal Chemistry 2010-01-01

Synthesis, NMR characterization and divergent biological actions of 2′-hydroxy-ceramide/dihydroceramide stereoisomers in MCF7 cells

Zdzislaw M. Szulc, Aiping Bai, Jacek Bielawski, Nalini Mayroo, Doreen E. Miller, Hanna Gracz, Yusuf A. Hannun, Alicja Bielawska, Zdzislaw M. Szulc, Aiping Bai, Jacek Bielawski, Nalini Mayroo, Doreen E. Miller, Hanna Gracz, Yusuf A. Hannun, Alicja Bielawska

Index: Bioorg. Med. Chem. 18 , 7565-79, (2010)

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Abstract

A straightforward method for the simultaneous preparation of (2S,3R,2'R)- and (2S,3R,2'S)-2'-hydroxy-ceramides (2'-OHCer) from (2S,3R)-sphingosine acetonide precursors and racemic mixtures of 2-hydroxy fatty acids (2-OHFAs) is described. The obtained 2'-OH-C4-, -C6-, -C12-, -C16-Cer and 2'-OH-C6-dhCer pairs of diastereoisomers were characterized thoroughly by TLC, MS, NMR, and optical rotation. Dynamic and multidimensional NMR studies provided evidence that polar interfaces of 2'-OHCers are extended and more rigid than observed for the corresponding non-hydroxylated analogs. Stereospecific profile on growth suppression of MCF7 cells was observed for (2'R)- and (2'S)-2'-OH-C6-Cers and their dihydro analogs. The (2'R)-isomers were more active than the (2'S)-isomers (IC(50) ∼3 μM/8 μM and IC(50) ∼8 μM/12 μM, respectively), surpassing activity of the ordinary C6-Cer (IC(50) ∼12 μM) and C6-dhCer (IC(50) ∼38 μM). Neither isomer of 2'-OH-C6-Cers and 2'-OH-C6-dhCers was metabolized to their cellular long chain 2'-OH-homologs. Surprisingly, the most active (2'R)-isomers did not influence the levels of the cellular Cers nor dhCers. Contrary to this, the (2'S)-isomers generated cellular Cers and dhCers efficiently. In comparison, the ordinary C6-Cer and C6-dhCer also significantly increased the levels of their cellular long chain homologs. These peculiar anabolic responses and SAR data suggest that (2'R)-2'-OHCers/dhCers may interact with some distinct cellular regulatory targets in a specific and more effective manner than their non-hydroxylated analogs. Thus, stereoisomers of 2'-OHCers can be potentially utilized as novel molecular tools to study lipid-protein interactions, cell signaling phenomena and to understand the role of hydroxylated sphingolipids in cancer biology, pathogenesis and therapy.Published by Elsevier Ltd.