Overexpression of protein kinase C-delta and -epsilon in NIH 3T3 cells induces opposite effects on growth, morphology, anchorage dependence, and tumorigenicity

• Published in: The Journal of biological chemistry 1993-03, Vol.268 (9), p.6090-6096
• Main Authors: MISCHAK, H, GOODNIGHT, J, KOLCH, W, MARTINY-BARON, G, SCHAECHTLE, C, KAZANIETZ, M. G, BLUMBERG, P. M, PIERCE, J. H, MUSHINSKI, J. F
• Format: Article
• Language: English
• Subjects: 3T3 Cells; Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Biological Transport; Blotting, Northern; Blotting, Western; Brain - enzymology; Cell Adhesion - drug effects; Cell Division - drug effects; Cell Transformation, Neoplastic; Cloning, Molecular; Enzyme Activation; Enzyme Stability; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Indoles - pharmacology; Isoenzymes - genetics; Isoenzymes - metabolism; Kinetics; Maleimides - pharmacology; Mice; Mice, Inbred C57BL; Mice, Nude; Neoplasms, Experimental - etiology; Protein Kinase C - genetics; Protein Kinase C - metabolism; Tetradecanoylphorbol Acetate - pharmacology; Transferases
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)53223-3

We have determined the patterns of mRNA and protein expression of 7 protein kinase C (PKC) isozymes in NIH 3T3 cells. Only PKC-alpha is expressed abundantly in NIH 3T3 cells; endogenous levels of the other 6 PKC isozymes are low or undetectable. We have overexpressed PKC-delta and -epsilon in these cells to observe activation/translocation of these two isozymes and the biological consequences of overexpression. Both PKC-delta and -epsilon, but not PKC-alpha, are partially associated with the insoluble fraction even in the absence of phorbol 12-myristate 13-acetate (PMA). Upon PMA stimulation, both PKC-delta and -epsilon translocate to the insoluble fraction of cell homogenates, as can be observed with the endogenous PKC-alpha. Overexpression of PKC-delta induces significant changes in morphology and causes the cells to grow more slowly and to a decreased cell density in confluent cultures. These changes are accentuated by treatment with PMA. Overexpression of PKC-epsilon does not lead to morphological changes, but causes increased growth rates and higher cell densities in monolayers. None of the PKC-delta overexpressers grow in soft agar with or without PMA, but all the cell lines that overexpress PKC-epsilon grow in soft agar in the absence of PMA, but not in its presence. NIH 3T3 cells that overexpress PKC-epsilon also form tumors in nude mice with 100% incidence. This indicates that high expression of PKC-epsilon contributes to neoplastic transformation.