Selective activation of protein kinase C-delta and -epsilon by 6,11,12,14-tetrahydroxy-abieta-5,8,11,13-tetraene-7-one (coleon U).
6,11,12,14-tetrahydroxy-abieta-5,8,11,13-tetraene-7-one (coleon U) is a diterpene compound isolated from Plectranthus grandidentatus with an antiproliferative effect on several human cancer cell lines. Herein, we studied the modulatory activity of coleon U on individual isoforms of the three protein kinase C (PKC) subfamilies, classical (cPKC-alpha and -betaI), novel (nPKC-delta and -epsilon) and atypical (aPKC-zeta), using a yeast PKC assay. The results showed that, whereas the PKC activator phorbol-12-myristate-13-acetate (PMA) activated every PKC tested except aPKC, coleon U had no effect on aPKC and cPKCs. Besides, the effect of coleon U on nPKCs was higher than that of PMA. This revealed that coleon U was a potent and selective activator of nPKCs. The isoform-selectivity of coleon U for nPKC-delta and -epsilon was confirmed using an in vitro PKC assay. Most importantly, while PMA activated nPKCs inducing an isoform translocation from the cytosol to the plasma membrane and a G2/M cell cycle arrest, coleon U induced nPKCs translocation to the nucleus and a metacaspase- and mitochondrial-dependent apoptosis. This work therefore reconstitutes in yeast distinct subcellular translocations of a PKC isoform and the subsequent distinct cellular responses reported for mammalian cells. Together, our study identifies a new isoform-selective PKC activator with promising pharmacological applications. Indeed, since coleon U has no effect on cPKCs and aPKC, recognised as anti-apoptotic proteins, and selectively induces an apoptotic pathway dependent on nPKC-delta and -epsilon activation, it represents a promising compound for evaluation as an anti-cancer drug.
Coutinho
I
I
Laboratório de Microbiologia, REQUIMTE/CEQUP, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, 164, 4050-047 Porto, Portugal.
Pereira
G
G
Simões
M F
MF
Côrte-Real
M
M
Gonçalves
J
J
Saraiva
L
L
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D004224:Diterpenes / Q000494:pharmacology*; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology*; D051745:Protein Kinase C-delta / Q000378:metabolism*; D051744:Protein Kinase C-epsilon / Q000378:metabolism*; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects
D004224:Diterpenes; D020536:Enzyme Activators; C469377:coleon U; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon