Apicularen A induces cell death through Fas ligand up-regulation and microtubule disruption by tubulin down-regulation in HM7 human colon cancer cells

作者:Kim Jong Seok; Lee Young Chu; Nam Ho Tak; Li Ge; Yun Eun Jin; Song Kyoung Sub; Seo Kang Sik; Park Ji Hoon; Ahn Jong Woong; Zee OkPyo; Park Jong Il; Yoon Wan Hee; Lim Kyu*; Hwang Byung Doo
来源:Clinical Cancer Research, 2007, 13(21): 6509-6517.
DOI:10.1158/1078-0432.CCR-07-1428

摘要

Purpose: Apicularen A has been shown to cause growth inhibition and apoptosis in several cancer cell lines. However, the mechanisms of apicularen A-induced cell death and in vivo effects remain unclear. In this study, we investigated the molecular mechanisms of apicularen A-induced cell death in HM7 human colon cancer cells in vitro and anticancer activity in vivo. Experimental Design: We tested cytotoxicity with a 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide, apoptosis with DNA fragmentation assay, mitochondrial membrane potential, and cell cycle with fluorescence-activated cell sorting. Caspase activation was done by fluorometry. Alterations of microtubule structure, tubulin protein, and mRNA level were assessed by immunofluorescence, Western blot, and reverse transcription- PCR. In vivo studies were assessed using nude mice tumor cell growth in xenograft model and liver colonization assay. Results: Apicularen A treatment of HM7 cells inhibited cell growth and this inhibition was partially rescued by z-VAD-fmk. Apicularen A caused accumulation of sub-G(1)-G(0), DNA fragmentation, Fas ligand induction, and activation of caspase-8 and caspase-3, but mitochondrial membrane potential was not changed. Furthermore, beta-tubulin protein and mRNAwere decreased by apicularen A, but in vitro polymerization of tubulin was not affected. Concurrently, apicularen A -treated cell showed disruption of microtubule architecture. In in vivo studies, apicularen A reduced tumor volume by similar to 72% at the end of a 15-day treatment. Moreover, apicularen A reduced liver colonization as much as 95.6% (50 mu g/kg/d). Conclusion: Apicularen A induces cell death of HM7 cells through up-regulating Fas ligand and disruption of microtubule architecture with down-regulation of tubulin level. These findings indicate that apicularen A is a promising new microtubule-targeting compound.