Trichostatin A sensitizes human ovarian cancer cells to TRAIL-induced apoptosis by down-regulation of c-FLIPL via inhibition of EGFR pathway.
TRAIL-resistant cancer cells can be sensitized to TRAIL by combination therapy. In this study, we investigated the effect of trichostatin A (TSA), a histone deacetylase inhibitor, to overcome the TRAIL resistance in human ovarian cancer cells. Co-treatment of human ovarian cancer cells with TSA and TRAIL synergistically inhibited cell proliferation and induced apoptosis. The combined treatment of ovarian cancer SKOV3 cells with TSA and TRAIL significantly activated caspase-8 and truncated Bid, resulting in the cytosolic accumulation of cytochrome c as well as the activation of caspase-9 and -3. Moreover, we found that down-regulation of c-FLIP(L) might contribute to TSA-mediated sensitization to TRAIL-induced apoptosis in SKOV3 cells, and this result was supported by showing that down- or up-regulation of c-FLIP(L) with transfection of siRNA or plasmid sensitized or made SKOV3 cells resistant to TRAIL-induced apoptosis, respectively. TSA or co-treatment with TSA alone and TRAIL also resulted in down-regulation of EGFR1/2 and dephosphorylation of its downstream targets, AKT and ERK. Treatment of SKOV3 cells with PKI-166 (EGFR1/2 inhibitor), LY294002 (AKT inhibitor), and PD98059 (ERK inhibitor) decreased c-FLIP(L) expression and co-treatment with TRAIL further reduced the level of c-FLIP(L,) respectively, as did TSA. Collectively, our data suggest that TSA-mediated sensitization of ovarian cancer cells to TRAIL is closely correlated with down-regulation of c-FLIP(L) via inhibition of EGFR pathway, involving caspase-dependent mitochondrial apoptosis, and combination of TSA and TRAIL may be an effective strategy for treating TRAIL-resistant human ovarian cancer cells.
Department of Biochemistry and Research Center for Ischemic Tissue regeneration, Pusan National University School of Medicine, Busan 602-739, South Korea.
Soo-Jung
SJ
Park
Mi-Ju
MJ
Kim
Hak-Bong
HB
Kim
Hee-Young
HY
Sohn
Jae-Ho
JH
Bae
Chi-Dug
CD
Kang
Sun-Hee
SH
Kim
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053181:Caspase 8 / Q000096:biosynthesis; D061945:Caspase Inhibitors; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004357:Drug Synergism; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D005260:Female; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D010051:Ovarian Neoplasms / Q000378:metabolism* / Q000473:pathology; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000096:biosynthesis / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*
D000970:Antineoplastic Agents; D061945:Caspase Inhibitors; D006877:Hydroxamic Acids; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; C012589:trichostatin A; C512478:EGFR protein, human; D066246:ErbB Receptors; C505530:CASP8 protein, human; D053181:Caspase 8