Resveratrol dimers are novel sphingosine kinase 1 inhibitors and affect sphingosine kinase 1 expression and cancer cell growth and survival

Sphingosine kinase 1 catalyses formation of the bioactive lipid, sphingosine 1-phosphate, which protects cancer cells from apoptosis. Therefore, sphingosine kinase 1 is a novel target for intervention with anti-cancer agents. We have assessed the effect of the anti-cancer agent, resveratrol and its dimers (ampelopsin A and balanocarpol) on sphingosine kinase 1 activity and on survival of MCF-7 breast cancer cells. Ampelopsin A and balanocarpol were purified from Hopea dryobalanoides and their effect on sphingosine kinase 1 activity and expression, [3H] thymidine incorporation, ERK-1/2 phosphorylation and PARP activity assessed in MCF-7 cells. Resveratrol, ampelopsin A and balanocarpol were novel inhibitors of sphingosine kinase 1 activity. Balanocarpol was a mixed inhibitor (with sphingosine) of sphingosine kinase 1 with a Kic= 90 +/- 10 mu M and a Kiu of similar to 500 mu M. Balanocarpol and ampelopsin A also induced down-regulation of sphingosine kinase 1 expression and reduced DNA synthesis, while balanocarpol stimulated PARP cleavage in MCF-7 breast cancer cells. Resveratrol was a competitive inhibitor (with sphingosine) of sphingosine kinase 1 with a Kic= 160 +/- 40 mu M, reduced sphingosine kinase 1 expression and induced PARP cleavage in MCF-7 cells. Each molecule of balanocarpol may bind at least two sphingosine kinase 1 catalytic molecules to reduce the activity of each simultaneously. These findings suggest that resveratrol, ampelopsin A and balanocarpol could perturb sphingosine kinase 1-mediated signalling and this might explain their activity against MCF-7 breast cancer cells. This article is commented on by Hergst and Yun, pp. 16031604 of this issue. To view this commentary visit