Involvement of PKC betaII in anti-proliferating action of a new antitumor compound gnidimacrin.
Daphnane-type diterpene gnidimacrin (NSC 252940) shows significant antitumor activity against murine tumors and human tumor cell lines. This compound binds to and directly activates protein kinase C (PKC), arresting the cell cycle at the G(1) phase through inhibition of cdk2 activity in human K562 leukemia cells. In our study, we examined whether cellular PKC is involved in the antiproliferating effect of gnidimacrin. In a 24-hr exposure of K562 cells to high concentrations of bryostatin 1 (0.11-3.3 microM), both expression of PKC alpha and PKC betaII was downregulated, and thereafter these cells became resistant to gnidimacrin in response to the degree of PKC downregulation. In addition, PKC alpha and PKC betaII genes were transfected to gnidimacrin-resistant human hepatoma HLE cells that demonstrated positive expression of PKC alpha and negative expression of PKC betaII. PKC betaII gene-transfected cells became sensitive to gnidimacrin in relation to the degree of PKC betaII expression. The most sensitive clone to show 0.001 microg/mL (1.2 nM) as IC(50) in a continuous 4-day exposure was obtained. While PKC alpha gene-transfected cells exhibited an increase in PKC alpha expression and became sensitive to gnidimacrin, sensitivity was one-hundredth of that in PKC betaIotaIota gene-transfected cells. These results suggest that PKC, in particular PKC betaIotaIota, is necessary in the antitumor effect of gnidimacrin.
National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan. myoshida@gan2.res.ncc.go.jp
Mitsuzi
M
Yoshida
Yuji
Y
Heike
Shigeo
S
Ohno
Tetsuro
T
Ikekawa
Hiro
H
Wakasugi
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D054713:Bryostatins; D042846:CDC2-CDC28 Kinases; D018288:Carcinoma, Small Cell / Q000473:pathology; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D004224:Diterpenes / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D004789:Enzyme Activation / Q000187:drug effects; D004790:Enzyme Induction / Q000187:drug effects; D016193:G1 Phase / Q000187:drug effects; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D018922:HL-60 Cells / Q000187:drug effects; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D020014:K562 Cells / Q000187:drug effects; D007783:Lactones / Q000494:pharmacology; D008175:Lung Neoplasms / Q000473:pathology; D018942:Macrolides; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D011493:Protein Kinase C / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011993:Recombinant Fusion Proteins / Q000502:physiology; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000201:enzymology
D000972:Antineoplastic Agents, Phytogenic; D054713:Bryostatins; D004224:Diterpenes; D007527:Isoenzymes; D007783:Lactones; D018942:Macrolides; D009363:Neoplasm Proteins; D011993:Recombinant Fusion Proteins; C046785:bryostatin 1; C013006:gnidimacrin; D017346:Protein Serine-Threonine Kinases; C496628:PRKCA protein, human; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases