We have previously demonstrated that the
protein kinase C (PKC) activity of human
glioma cell lines was significantly elevated (by 3 orders of magnitude) when compared to non-malignant adult human glia, and that the proliferation rate of several established human
glioma cell lines correlated with the measured
protein kinase C activity. The purpose of this study was to determine whether 1) elevated PKC activity was also a characteristic of fast growing cell lines of non-glial origin, 2) the proliferation rate of non-
glioma cell lines correlated with their PKC activity and 3) the proliferation of non-
glioma cell lines could be inhibited by
staurosporine, a relatively selective PKC inhibitor, which significantly attenuates the growth of
glioma cells. Eight established human non-
glioma cell lines (bladder, colorectal,
rhabdomyosarcoma-oligodendrocyte hybrid,
melanoma, cervix, and fibroblast) were compared to the highly proliferative A172
glioma cell line. PKC activity was significantly higher in the
glioma cell lines even though 3 of 8 of the non-
glioma lines had higher proliferation rates than A172. In non-
glioma cell lines, no correlation was found between the PKC activity and proliferation rates.
Staurosporine was more effective in decreasing the proliferation of three
glioma cell lines compared to the non-
glioma cell lines. We conclude that PKC activity is differentially increased in
glioma cell lines and that their proliferation rate is more sensitive to inhibition by
staurosporine. Targetting the PKC system may prove to be of therapeutic benefit to patients with
malignant gliomas.