Ex vivo assays to evaluate the role of protein kinase C in tumor cells of patients with breast cancer

New anti-cancer strategies have been developed with respect to proteinkinas e C (PKC) as a potential target for therapeutic intervention in patients wi th advanced breast cancer: Using cell lines, most of the preliminary data a re encouraging but insufficient information is available concerning clinica l breast cancer. cells. Thus, we decided to clarify the involvement of PKC in clinical breast carcinoma cells. We isolated viable tumor cells from flu ids or tissue burden of eleven patients with advanced breast cancer: Perfor mance of short term cultures supplemented with commonly used antineoplastic s mimicked the clinical situation. We determined the ex vivo chemosensitivi ty pattern of each cell population. Additionally, we analysed total PKC act ivity and quantified the PKC-isoform zeta. All assays showed a heterogeneou s highly variable distribution of the data investigated No tendency could b e observed regarding the influence of the therapeutics on PKC activity, PKC -zeta expression ol chemoresistance, respectively. Moreover; changes in nei ther PKC-zeta expression, PKC activity nor chemoresistance induced by a par ticular drug in an individual tumor necessarily predicted the same reaction in another tumor. to this agent. Therefore, we concluded that more explora tive data concerning this topic are required prior to the development of a clinically useful therapy regimen with PKC as the major target.