CYTOKINETIC EFFECTS OF CISPLATIN ON DIVERSE HUMAN HEAD AND NECK CARCINOMAS IN-VITRO - DEPENDENCE ON THE TUMOR SENSITIVITY TO CISPLATIN

Studies performed with xenografted human head and neck carcinomas in v ivo have demonstrated that the cytokinetic phenomena occurring under t he influence of cisplatin closely correlate with the response of the t umors to therapy. The present paper analyses whether this correlation also exists in vitro. Four human head and neck carcinoma cell lines sh owing different degrees of sensitivity to cisplatin, as determined by the trypan blue exclusion assay, were investigated by flow cytometry a t various intervals after administration of cisplatin, Early cell-cycl e blockades in the S phase always reflected a high degree of cytostati c potency of cisplatin and were usually succeeded by a pronounced inhi bition of tumor cell proliferation and a reduction of cell viability. In the case of a minimal response to therapy and in untreated control cultures of all four tumor lines, the relative number of S-phase cells continuously diminished during the observation period. These findings point to the S-phase blockade as the crucial cytokinetic effect of ci splatin preceding relevant growth reductions, This knowledge might sup port the development of a drug-response assay that could predict the s ensitivity of individual patient tumors in vitro before the beginning of clinical cancer chemotherapy.