Differential responses of staurosporine on protein kinase C activity and proliferation in two murine neuroblastoma cell lines.

We studied the effect of staurosporine (SSP), a broad-spectrum protein kinase inhibitor, on the levels of protein kinase C (PKC) activity and proliferation in two murine neuroblastoma cell lines, Neuro2a and its clone NB41A3. The PKC activity was examined in whole cell lysate, cytosolic and particulate fractions. A differential response to SSP treatment in the enzyme activity in whole cell lysate and particulate fractions was demonstrated in the two cell lines. The data on proliferation indicated that Neuro2a cells were more sensitive to the SSP treatment with significant inhibition in DNA synthesis in a time course study. Our findings suggest that the data on basal levels of PKC activity in tumors will be of significance in studies using PKC inhibitors as an approach for therapeutic intervention.