ACTIVATION OF NF-KAPPA-B BY ANTINEOPLASTIC AGENTS - ROLE OF PROTEIN-KINASE-C

Paclitaxel can induce tumor necrosis factor (TNF) and interleukin-1 ge ne expression, similar to lipopolysaccharides, Since lipopolysaccharid e-induced expression of TNF is related to activation of NF-kappa B, we determined whether NP-kappa B could be activated by paclitaxel. In th e human lung adenocarcinoma cell line A549, paclitaxel activated NF-ka ppa B in a dose-dependent manner with maximal activation after 2-4 h, Since paclitaxel could upregulate TNF and interleukin-1 secretion and subsequent NF-kappa B activation could be caused by these cytokines, t he effect of two other groups of anticancer drugs including vinca alka loids (vinblastine and vincristine) and anthracyclines (daunomycin and doxorubicin), neither of which induce TNF or interleukin-1 gene expre ssion, were examined, Like paclitaxel, vinblastine, vincristine, dauno mycin, and doxorubicin each caused activation of NF-kappa B. Therefore , it is unlikely that activation of NF-kappa B caused by these agents or by paclitaxel is mediated via cytokine up-regulation. Furthermore, actinomycin D and cycloheximide, inhibitors of transcription and trans lation, respectively, did not inhibit paclitaxel-induced NF-kappa B ac tivation, Several other transcription factors such as AP-1, AP-2, CREB , SP-1, or TFIID were not activated by antineoplastic agents demonstra ting specificity of NF-kappa B activation, The involvement of both sub units in the NF-kappa B DNA binding complex was demonstrated by its ab rogation by anti-p65 and by supershift by anti-p50 antibodies. Since p rotein phosphorylation is implicated in the activation of NF-kappa B, the effect of anticancer drugs on protein kinase C activity was measur ed, Vincristine, daunomycin, and paclitaxel significantly increased pr otein kinase C activity, and vinblastine and doxorubicin caused simila r trends, Following treatment with antineoplastics (1-4 h), cytoplasmi c I kappa B alpha degradation occurred concomitantly with translocatio n of p65 to the nucleus, Specific protein kinase C inhibitors (bisindo lylmaleimide (GF109203X) and calphostin C) blocked the activation of N F-kappa B by each compound. Hence, protein kinase C activation may con tribute to NF-kappa B activation by antineoplastic agents.