Curcumin-induced apoptosis in ovarian carcinoma cells is p53-independent and involves p38 mitogen-activated protein kinase activation and downregulation of Bcl-2 and survivin expression and Akt signaling.
New cytotoxic agents are urgently needed for the treatment of advanced ovarian cancer because of the poor long-term response of this disease to conventional chemotherapy. Curcumin, obtained from the rhizome of Curcuma longa, has potent anticancer activity; however, the mechanism of curcumin-induced cytotoxicity in ovarian cancer cells remains a mystery. In this study we show that curcumin exhibited time- and dose-dependent cytotoxicity against monolayer cultures of ovarian carcinoma cell lines with differing p53 status (wild-type p53: HEY, OVCA429; mutant p53: OCC1; null p53: SKOV3). In addition, p53 knockdown or p53 inhibition did not diminish curcumin killing of HEY cells, confirming p53-independent cytotoxicity. Curcumin also killed OVCA429, and SKOV3 cells grown as multicellular spheroids. Nuclear condensation and fragmentation, as well as DNA fragmentation and poly (ADP-ribose) polymerase-1 cleavage in curcumin-treated HEY cells, indicated cell death by apoptosis. Procaspase-3, procaspase-8, and procaspase-9 cleavage, in addition to cytochrome c release and Bid cleavage into truncated Bid, revealed that curcumin activated both the extrinsic and intrinsic pathways of apoptosis. Bax expression was unchanged but Bcl-2, survivin, phosphorylated Akt (on serine 473), and total Akt were downregulated in curcumin-treated HEY cells. Curcumin also activated p38 mitogen-activated protein kinase (MAPK) without altering extracellular signal-regulated kinase 1/2 activity. We conclude that p53-independent curcumin-induced apoptosis in ovarian carcinoma cells involves p38 MAPK activation, ablation of prosurvival Akt signaling, and reduced expression of the antiapoptotic proteins Bcl-2 and survivin. These data provide a mechanistic rationale for the potential use of curcumin in the treatment of ovarian cancer.
Watson
Jane L
JL
Department of Surgery, Dalhousie University, Halifax, Nova Scotia, Canada.
Greenshields
Anna
A
Hill
Richard
R
Hilchie
Ashley
A
Lee
Patrick W
PW
Giacomantonio
Carman A
CA
Hoskin
David W
DW
D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003474:Curcumin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D051058:Oncogene Protein v-akt / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects; D018874:Spheroids, Cellular / Q000187:drug effects / Q000378:metabolism; D000077022:Survivin; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D000970:Antineoplastic Agents; C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D000077022:Survivin; D016159:Tumor Suppressor Protein p53; D051058:Oncogene Protein v-akt; D048051:p38 Mitogen-Activated Protein Kinases; D003474:Curcumin