Effects of neoplastic transformation and teniposide (VM26) on protein kinase C isoform expression in rodent fibroblasts

This study examined changes in protein kinase C (PKC) isoforms in rodent fibroblasts (rat F111 and mouse NIH3T3), transformed by the polyoma virus middle T antigen (mT) and undergoing apoptosis in response to teniposide (VM26). The mT-transformed cells up-regulated PKC δ and down-regulated both PKC ε and PKC λ expression, and were more sensitive to the drug than their non-transformed counterparts. The drug treatment further lowered the expression of PKC ε, triggered nuclear translocation of PKC δ and its site-specific proteolysis, consistent with the notion that changes in specific PKC isoforms play a role not only in the neoplastic transformation of fibroblasts, but also in their apoptotic response.