PKC-DEPENDENT MODULATION OF IKB-ALPHA-NFKB PATHWAY IN LOW METASTATIC B16F1 MURINE MELANOMA-CELLS AND IN HIGHLY METASTATIC BL6 CELLS

Protein Kinase C (PKC) is a family of at least II closely related isof orms with different modality of activation, and intracellular and tiss ue distribution. The aim of the present work was to analyse the effect of treatment with 0.1 mu M TPA as well as treatment with specific inh ibitors of individual PKC isoenzymes (Go6976 for c-PKC alpha and beta isoforms and BIM for c-PKCs and n-PKCs isoforms), on the NF-kB/IkB alp ha pathway in the low and high metastatic B16F1 and BL6 murine melanom a cells. The DNA-binding activity of the transcription factors AP1, AP 2, CREB and OTC was also considered. Different modality of activation for NF-kB and AP1 was demonstrated in the two cell lines with the poss ible specific involvement of c-PKCs isoforms. In fact, in the high met astatic BL6 cells the long-term treatment for 24 hours with TPA, with no c-PKC activation or the inhibition with Go6976 as well as with BIM, induced an increased NF-kB and AP1 DNA-binding activity. In contrast, in the low metastatic B16F1 cells the short-term treatment with TPA, induced the activation of c-PKCs isoforms, and enhanced NF-kB and AP1 DNA-binding activity No significant changes were demonstrated for AP2, CREB and OTC DNA-binding activity in both cell lines.