PROTEIN-KINASE-C ISOFORMS AND CELL-PROLIFERATION IN NEUROBLASTOMA-CELLS

The expression of protein kinase C isoforms in the neuroblastoma cell line Neuro 2a has been studied. It is shown that Neuro 2a cells expres s alpha, delta, epsilon and zeta PKCs. Inhibition of cell proliferatio n by using protein kinase C inhibitors (H7 or calphostin C) or medium without glutamine affects markedly the pattern of PKC isoforms. All tr eatments reduced significantly (50-70%) the content of PKC alpha. None of the treatments altered PKC zeta or epsilon. The content of PKC del ta was increased (88-120%) in cells treated with PKC inhibitors but wa s slightly reduced in cells incubated in medium without glutamine. How ever, none of the treatments affected the content of the corresponding mRNAs. Long-term treatment of synchronized cells with the phorbol est er PMA depletes PKC alpha but not PKC delta or zeta and only partially PKC epsilon. This treatment with PMA did not affect DNA synthesis, in dicating that PKC alpha does not play a significant role in the contro l of proliferation of these cells.