Synergistic effects of retinoic acid and 8-Cl-cAMP on apoptosis require caspase-3 activation in human ovarian cancer cells.
We investigated the intracellular mechanisms of retinoic acid (9-cis-RA, 13-cis-RA or all-trans-RA) and a cyclic AMP analog 8-Cl-cAMP on growth-inhibition and apoptosis in human ovarian cancer NIH: OVCAR-3 and OVCAR-8 cells. The cyclic AMP analog, 8-Cl-cAMP, acted synergistically with RA in inducing and activating retinoic acid receptor beta (RARbeta) which correlated with the growth inhibition, cell cycle arrest, and apoptosis in both cell types. In addition, combined treatment of cells with RA plus 8-Cl-cAMP resulted in the release of cytochrome c, loss in mitochondrial membrane potential and activation of caspase-3 followed by cleavage of anti-poly(ADP-ribose)polymerase and DNA-dependent protein kinase (catalytic subunit). Interestingly, inhibition of caspase-3 activation blocked RA plus 8-Cl-cAMP induced apoptosis. Furthermore, mutations in a CRE-related motif within the RARbeta promoter resulted in loss of both transcriptional activation of RARbeta and synergy between RA and 8-Cl-cAMP. Thus, RARbeta can mediate RA and/or cyclic AMP action in ovarian cancer cells by promoting apoptosis. Loss of RARbeta expression, therefore, may contribute to the tumorigenicity of human ovarian cancer cells. These findings suggest that RA and 8-Cl-cAMP act in a synergistic fashion in inducing apoptosis via caspase-3 activation, and may have potential for combination biotherapy for the treatment of malignant disease such as ovarian cancer.
Srivastava
R K
RK
Laboratory of Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224-6825, USA.
Srivastava
A R
AR
Cho-Chung
Y S
YS
Longo
D L
DL
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D000595:Amino Acid Sequence; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003574:Cytochrome c Group / Q000378:metabolism; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D004357:Drug Synergism; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D010051:Ovarian Neoplasms; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D014212:Tretinoin / Q000378:metabolism* / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D003574:Cytochrome c Group; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D018168:Receptors, Retinoic Acid; C082925:retinoic acid receptor beta; D015124:8-Bromo Cyclic Adenosine Monophosphate; D014212:Tretinoin; C044258:8-chloro-cyclic adenosine monophosphate; D011065:Poly(ADP-ribose) Polymerases; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases