Rapid assay for evaluating the chemosensitivity of human tumors in soft agar culture.

Abstract

Abstract Assays that measure [3H]thymidine incorporation by cells plated in soft agar were investigated to identify a rapid method for assessing chemosensitivity of tumor cells. Six established cell lines (five melanomas and one colon carcinoma) and cells prepared from 23 primary or metastatic tumors (ten melanomas, five colon adenocarcinomas, three lung carcinomas, two ovarian adenocarcinomas, one breast adenocarcinoma, and one leiomyosarcoma) were tested. The end point of tritium incorporation was measured by autoradiographs (labeling index) and scintillation counting (cpm) after 24-hr labeling. When results were compared, there was a strong correlation between the two assays (p However, the scintillation counting assay had major advantages: (a) counting incorporated radioisotope was technically easier than the autoradiographic method; (b) the DNA synthesis rate of the whole tumor cell population could be evaluated, not that of tumor colony-forming cells alone; and (c) the sampling error was minimized since the procedure was done automatically. There was significant association between cpm values 48 to 72 hr after plating and the number of colonies formed at 2 to 4 weeks in control dishes (p