Deletion of specific protein kinase C subspecies in human melanoma cells.
It has been shown that tumor-promoting phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), stimulates the proliferation of normal human melanocytes, whereas it inhibits the growth of human melanoma cell lines. The expression of protein kinase C (PKC) subspecies, the major intracellular receptors for TPA, was examined in normal melanocytes and the four melanoma cell lines HM3KO, MeWo, HMV-1, and G361. PKC was partially purified and then separated into subspecies by column chromatography on Mono Q and hydroxyapatite successively, and finally subjected to immunoblot analysis using antibodies specific for the PKC subspecies. Of the PKC subspecies examined, delta-, epsilon-, and zeta-PKC were detected in both normal melanocytes and the four melanoma cell lines. In contrast, both alpha-PKC and beta-PKC were expressed in normal melanocytes, whereas either alpha-PKC or beta-PKC was detected in melanoma cells. Specifically, HM3KO, MeWo, and HMV-1 cells were shown to contain alpha-PKC but not beta-PKC, while G361 cells expressed beta-PKC but not alpha-PKC. The growth of these melanoma cells was suppressed by TPA treatment, and the growth of the G361 cells lacking alpha-PKC was inhibited more efficiently than the other melanoma cell lines which lacked beta-PKC. It was further shown that beta-PKC was not detected in freshly isolated human primary or metastatic melanoma tissues. These results suggest that the expression of alpha-PKC or beta-PKC may be altered during the malignant transformation of normal melanocytes and that loss of alpha-PKC or beta-PKC may be related to the inhibitory effect of TPA on the growth of melanoma cells.
Oka
M
M
Department of Dermatology, Kobe University School of Medicine, Japan.
Ogita
K
K
Ando
H
H
Horikawa
T
T
Hayashibe
K
K
Saito
N
N
Kikkawa
U
U
Ichihashi
M
M
D002455:Cell Division / Q000187:drug effects; D002845:Chromatography; D017886:Durapatite; D006801:Humans; D015151:Immunoblotting; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D008544:Melanocytes / Q000187:drug effects / Q000201:enzymology; D008545:Melanoma / Q000201:enzymology* / Q000473:pathology; D011493:Protein Kinase C / Q000302:isolation & purification / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D007527:Isoenzymes; D017886:Durapatite; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate