A Fundamental Study of Tumor Sensitivity Test, SDI (Succucinic Dehydrogenase Inhibition) Test Using XTT

Abstract

Tumor sensitivity assays have been widely reported, and we have been performed SDI (succinic dehydrogenase inhibition) test using MTT.In this paper we have studied this test fundamentally by the use of a new synthesized tetrazolium salt, XTT.The assay is performed with 96-well microplates.In the assay using XTT, addition of appropriate concentration of PMS (phenazine methosulfate) to XTT results in a marked increase in optical density and continues to increase with reaction time, which means XTT is less toxic to cells than MTT. Therefore, we have studied from time to time the possibility of evaluation with a little number of cells comparing with MTT assay.Tumor cells used in this experiment are Sarcoma 180, Ehrlich carcinoma, NUGC4 and SW13 as human cell lines.
In result, when we incubate tumor cell over 20-h with XTT, we are able to evaluate sufficiently with a little number of cells, and we studied I.I.(Inhibition Index) of each drug (MMC, ADM, CDDP). XTT assay is easy to be influenced by pH and requires the use of medium contained buffer.Formazan formed from XTT is soluble in water, so that XTT assay does not require DMSO (dimethyl sulf oxide), but the problem is the measure of colored drugs for example ADM etc.It is thought that XTT is a useful tetrazolium salt and the assay is simple and able to evaluate with a little number of cells.