Suberoylanilide hydroxamic acid (SAHA) potentiates paclitaxel-induced apoptosis in ovarian cancer cell lines.
OBJECTIVE
To determine if SAHA, a histone deacetylase inhibitor, decreases ovarian cancer cell viability when combined with paclitaxel in vitro, and to explore molecular alterations of combined paclitaxel+SAHA treatment.


METHODS
SKOV3 and Hey ovarian cancer cell lines were treated for 24 h with paclitaxel, then re-treated with SAHA or paclitaxel for an additional 48 h. Protein extracts were prepared at 48 h for western blot analysis. Cell viability was assessed at 72 h using the ApoAlert Annexin V Apoptosis Kit.


RESULTS
SAHA causes G1 and G2 cell cycle arrest in ovarian cancer cell lines. Cell viability was significantly reduced by combined paclitaxel+SAHA treatment. In Hey cells, viability was reduced to 67% with paclitaxel, and to 48% with paclitaxel+SAHA (p<0.001). In the SKOV3 cell line, viability was reduced to 70% with continuous paclitaxel treatment, and was further reduced to 57% in the combined treatment group (p<0.05). Increased PARP cleavage was noted in the paclitaxel+SAHA groups. SAHA increased expression of p21cip1/waf1 and p27Kip1, down regulated cyclins A and B, and suppressed CDK1. Paclitaxel induced expression of survivin, an inhibitor of apoptosis protein, was reduced to baseline control levels with the addition of SAHA. The pro-apoptotic protein, Bad, was also increased with SAHA.


CONCLUSIONS
Paclitaxel+SAHA reduces cell viability in excess of either agent alone in ovarian cancer cell lines. Cell death is mediated via several mechanisms including G1/G2 arrest from CDK1 downregulation, inhibition of paclitaxel-induced survivin accumulation, and from increased Bad expression.
Dietrich
Charles S
CS
Gynecologic Oncology Service, Department of Obstetrics and Gynecology, Tripler Army Medical Center, 1 Jarrett White Road, Honolulu, HI 96859-5000, USA. chuck.dietrich@us.army.mil
Greenberg
Victoria L
VL
DeSimone
Christopher P
CP
Modesitt
Susan C
SC
van Nagell
John R
JR
Craven
Rolf
R
Zimmer
Stephen G
SG
D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D016203:CDC2 Protein Kinase / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D019926:Cyclin B / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D004357:Drug Synergism; D005260:Female; D006801:Humans; D006877:Hydroxamic Acids / Q000008:administration & dosage / Q000494:pharmacology*; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000473:pathology; D017239:Paclitaxel / Q000008:administration & dosage / Q000494:pharmacology*; D000077337:Vorinostat
D019926:Cyclin B; D006877:Hydroxamic Acids; D000077337:Vorinostat; D016203:CDC2 Protein Kinase; D017239:Paclitaxel