Different chemosensitivities of rat 3Y1 fibroblasts transformed by various agents in vitro

Alterations of chemosensitivities associated with transformation of rat 3Y1 fibroblasts were compared among various agents, including either adenovirus type 12 (Ad12-3Y1), the E1A region of adenovirus type 12 (E1A-3Y1), mouse polyoma virus (Py-3Y1), Simian virus 40 (SV-3Y1), Rous avian sarcoma virus (SR-3Y1), plasmid DNA carrying v-Ha-ras oncogene (HR-3Y1), or N-methyl-N'-nitro-N-nitrosoguanidine (NG-3Y1), with untransformed 3Y1 fibroblasts, using a semiautomated non-clonogenic MTT assay. IC₅₀ values were compared for each drug in each cell line. Among the different cell lines, untransformed 3Y1 cells were the most resistant to cisplatin (CDDP), adriamycin (ADM), carboquone (CQ), bleomycin (BLM), mitomycin C (MMC) and 4-hydroperoxy cyclophosphamide (4-hp-CPA). On the other hand, E1A-3Y1 cells were more resistant to vincristine (VCR) and NG-3Y1 and Ad12-3Y1 were more resistant to 5-fluorouracil (5-FU) than untransformed 3Y1 cells. These transformed lines did not display any cross-resistance to other drugs. The dissociation of chemosensitivities between Ad12-3Y1 and E1A-3Y1 to ADM, VCR and 5-FU was recognized. These results suggested that some of these transforming agents may alter the chemosensitivities of anticancer drugs.