Expression of protein kinase C isoforms in euxanthone-induced differentiation of neuroblastoma cells.
Euxanthone, a potent neuritogenic compound isolated from the roots of the medicinal herb Polygala caudata, has recently been shown to induce the differentiation of murine neuroblastoma Neuro 2A (BU-1) cells. In this study, the role of protein kinase C (PKC) and the expression of various PKC isoforms in euxanthone-treated BU-1 cells were examined. mRNA phenotyping using the reverse-transcription polymerase chain reaction (RT-PCR) showed that BU-1 cells express six different PKC isoforms, namely PKC-alpha, -beta, -delta, -epsilon, -lambda, and -zeta. Differential regulation and expression of PKC isoforms was observed in BU-1 cells treated with 100 microM euxanthone. PKC-apha, -beta, -delta, -lambda and -zeta were all up-regulated, with 1.7- to 9.5-fold increase, at around 30 to 60 minutes after euxanthone treatment. The expression level of PKC-epsilon remained relatively constant during the treatment. PKC-gamma, -eta, and -theta were not detected in both untreated and euxanthone-treated BU-1 cells. Staurosporine, a broad spectrum PKC inhibitor, was found to inhibit both spontaneous and euxanthone-induced neuritogenesis in BU-1 cells. A significant reduction of the euxanthone-induced neuritogenic effect was also observed when the PKC isoform-specific inhibitor Go6976 was included in the culture. These results suggest that the euxanthone-induced differentiation of the neuroblastoma BU-1 cells may be mediated through the differential expression of PKC-alpha, -beta, -delta, -lambda and -zeta isoforms.
Mak
N K
NK
Department of Biology, The Hong Kong Baptist University, Kowloon Tong.
Lung
H L
HL
Wong
R N
RN
Leung
H W
HW
Tsang
H Y
HY
Leung
K N
KN
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D002227:Carbazoles / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D051379:Mice; D016501:Neurites / Q000187:drug effects; D009447:Neuroblastoma / Q000201:enzymology* / Q000648:ultrastructure; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D019685:Rosales / Q000737:chemistry*; D019311:Staurosporine / Q000494:pharmacology; D014966:Xanthenes / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D044004:Xanthones
D000972:Antineoplastic Agents, Phytogenic; D002227:Carbazoles; D004791:Enzyme Inhibitors; D007211:Indoles; D007527:Isoenzymes; D014966:Xanthenes; D044004:Xanthones; C081021:Go 6976; C404221:euxanthone; D011493:Protein Kinase C; D019311:Staurosporine