Phenethyl isothiocyanate (PEITC) inhibits growth of ovarian cancer cells by inducing apoptosis: role of caspase and MAPK activation.
OBJECTIVE
Epithelial ovarian cancer has the highest mortality rate among gynecologic cancers. Chemotherapy is an essential component of its treatment. While isothiocyanates are known to possess chemopreventive effects against various cancers, yet little is known about their chemotherapeutic potential in ovarian cancer (OC). In the present study, we examined the antiproliferative and apoptotic effect of phenethyl isothiocyanate (PEITC), a naturally occurring isothiocyanate on OVCAR-3 cells.


METHODS
Cytotoxic activity of PEITC on OVCAR-3 cells was determined using cell proliferation, apoptosis (DNA fragmentation and TUNEL assay) and caspase-activation studies. The role of PARP-1, Bax, and Bcl-2 in apoptosis was analyzed by Western blotting. Activation of JNK1/2, p38, Akt, ERK1/2, and c-Myc was examined by immunoblotting. Specific inhibitors of caspases, JNK1/2, p38, and MEK were used to corroborate these data.


RESULTS
PEITC was cytotoxic to OVCAR-3 cells, and inhibited proliferation in a dose-dependent fashion (IC(50) = 23.2 microM). PEITC induced apoptosis by activating caspase-3 and -9, without capsase-8 activation. Anti-apoptotic Bcl-2 levels were suppressed while pro-apoptotic Bax levels were enhanced. PEITC suppressed activation of Akt, ERK1/2, and the expression of transcription factor c-Myc, while simultaneously activating pro-apoptotic p38 and JNK1/2. Specific inhibitors of caspase-3 and -9, JNK1/2, and p38 reversed the cytotoxic effect of PEITC.


CONCLUSIONS
These findings demonstrate that PEITC exhibits cytotoxicity towards OVCAR-3 cells and induces apoptosis via caspase-9 and -3 pathways. PEITC inhibits Akt, ERK1/2 survival signaling, and c-Myc while simultaneously activating pro-apoptotic p38 and JNK1/2. Systematic preclinical and clinical trials with PEITC in ovarian cancer are indicated.
Satyan
K S
KS
Program in Women's Oncology, Department of Obstetrics and Gynecology, Women and Infants' Hospital, Brown University, Providence, RI 02905, USA.
Swamy
Narasimha
N
Dizon
Don S
DS
Singh
Rakesh
R
Granai
Cornelius O
CO
Brard
Laurent
L
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D053148:Caspase 3; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006801:Humans; D017879:Isothiocyanates / Q000494:pharmacology*; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
C494826:BAX protein, human; D061945:Caspase Inhibitors; D017879:Isothiocyanates; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; C058305:phenethyl isothiocyanate; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases