Caulerpenyne from Caulerpa taxifolia has an antiproliferative activity on tumor cell line SK-N-SH and modifies the microtubule network

Abstract

Caulerpenyne, the major secondary metabolite synthesized by the green marine alga Caulerpa taxifolia, is cytotoxic against several cell lines. To identify possible targets of this toxin, we investigated the effect of caulerpenyne on the neuroblastoma SK-N-SH cell line. Caulerpenyne induced an inhibition of SK-N-SH cell proliferation with an IC 50 of 10 ± 2 μM after 2 hr of incubation.We observed no blockage in G 2/M phase and an increase in cell death. On immunofluorescence microscopy, caulerpenyne affected the microtubule network in SK-N-SH cell line; we observed a loss of neurites and a compaction of the microtubule network at the cell periphery. In vitro, after 35 min of incubation, caulerpenyne inhibited the polymerization of pig brain purified tubulin or microtubule proteins, with an IC 50 of 21 ± 2 μM and 51 ± 6 μM respectively. Analysis by electron microscopy indicated that caulerpenyne induced aggregation of tubulin, which may be responsible for inhibition of microtubule polymerization and bundling of residual microtubules.