3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone [MX] shows initiating and promoting activities in a two-stage BALB/c 3T3 cell transformation assay.

A transformation assay using BALB/c 3T3 cells was conducted on 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) to assess initiation and promotion activities of MX carcinogenesis. Statistically significant positive responses were obtained compared with the corresponding solvent controls in both the initiation assay post-treated with 12-O-tetradecanoylphorbol 13-acetate (TPA) and the promotion assay pretreated with 3-methylcholanthrene (MCA). Both TPA and MX inhibited metabolic cooperation in an assay using co-culture of V79 6-thioguanine (6-TG) sensitive and insensitive cells. However, cells isolated from transformed foci in the initiation assay did not induce any nodules after inoculation to BALB/c mice, the strain of mouse from which the transformation assay cells were derived. Although the study was carried out for 2-3 weeks, this might have been too short to develop nodules under the conditions of this experiment. This in vitro cell transformation study with MX adds supportive information to studies showing MX carcinogenicity and tumour promoter activity, and adds mechanistic understanding of the action of MX.