Development and characterization of a protein kinase C β‐isozyme‐deficient T‐cell line

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Abstract
In the human T‐cell lymphoma line, HuT 78, proliferation and phorbol ester‐induced growth arrest and differentiation were inhibited by the protein kinase C (PKC) inhibitor, staurosporine. By contrast, an alternative PKC inhibitor, H‐7, inhibited proliferation but not phorbol ester‐induced growth arrest. The cell line was found to contain both α and β isoforms of PKC by Western blot techniques. A cell line, K‐4, was cloned from HuT 78 in the presence of H‐7 and this clone was found to be positive for PKC‐α only. PKC‐β did not return on cultivation in the absence of H‐7. Proliferation of K‐4 was insensitive to inhibition with both H‐7 and staurosporine. However, phorbol ester‐induced growth arrest remained staurosporine sensitive. Phorbol‐stimulated IL‐2 secretion was minimal in the PKC‐β‐deficient cell line. These data suggest that PKC‐β may be a regulatory enzyme for proliferation and stimulated interleukin‐2‐secretion in HuT 78 cells. Heterogeneity of responses to PKC activation may reflect the use of different isozymes in different intracellular pathways. The K‐4 cell line should provide a useful tool in the dissection of involvement of PKC isozymes in cellular function.