kappa-Opioid receptor potentiates apoptosis via a phospholipase C pathway in the CNE2 human epithelial tumor cell line.
The mechanism by which kappa-opioid receptor (kappaor) modulated apoptosis was investigated in CNE2 human epithelial tumor cells. Induction of these cells to undergo apoptosis with staurosporine was associated with a massive increase in intracellular cAMP level. The inhibition of the increase in cAMP partially inhibited apoptosis as evidenced by a reduction of PARP and caspase-3 cleavage. Accordingly, a low but significant level of apoptosis is induced in these cells by the elevation of cAMP through the addition of forskolin and isobutylmethylxanthine. The existence of a cAMP-dependent and a cAMP-independent apoptotic pathway is therefore suggested. Receptor binding studies, RT-PCR experiments and Western blot analysis demonstrated the presence of type 1 kappaor in the CNE2 cells. Stimulation of kappaor in these cells resulted in the production of inositol (1,4,5)-trisphosphate, reduction of cAMP level and a marked enhancement of staurosporine-induced apoptosis. The potentiation of apoptosis by kappaor was prevented by inhibition of phospholipase C but was slightly enhanced by the presence of the active cAMP analogues, 8-CPT-cAMP and dibutyryl-cAMP. These data demonstrate for the first time that the phospholipase C pathway activated by type 1 kappaor expressed by cancer cells is involved in the potentiation of apoptosis.
Diao
C T
CT
Department of Biochemistry, Faculty of Medicine, University of Hong Kong, PR China.
Li
L
L
Lau
S Y
SY
Wong
T M
TM
Wong
N S
NS
D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer / Q000494:pharmacology; D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology; D017209:Apoptosis; D001483:Base Sequence; D001575:Benzomorphans / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D016048:Dideoxyadenosine / Q000494:pharmacology; D004357:Drug Synergism; D004847:Epithelial Cells / Q000502:physiology*; D004963:Estrenes / Q000494:pharmacology; D006801:Humans; D008969:Molecular Sequence Data; D011760:Pyrrolidinones / Q000494:pharmacology; D017473:Receptors, Opioid, kappa / Q000187:drug effects / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D019311:Staurosporine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000502:physiology*
D001575:Benzomorphans; D004963:Estrenes; D011760:Pyrrolidinones; D017473:Receptors, Opioid, kappa; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C017759:9-(tetrahydro-2-furyl)-adenine; D005576:Colforsin; D016048:Dideoxyadenosine; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000242:Cyclic AMP; D010738:Type C Phospholipases; D019311:Staurosporine; C027248:bremazocine; D000225:Adenine