145 zyxwvutsr Cancer Letters, 64 (199.2) 14.5 - 153 Elsevier Scientific Publishers Ireland Ltd. Initiating activity of 1 , 1 ,2,2-tetrachloroethane in two-stage BALB/c 3T3 cell transformation Annamaria Colaccia, Paolo Peroccob, Silvana BartoliC, Claudia Da Viayb, Paola Silingardi b, Monica Vaccarib and Sandro Grillib “lstituto Nazionole zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA per la Ricerca sul Cancro (IST-Genoua), Biotechnology Satellite Unit-Bologna, bCentro Intercmiuer- sitario per la Ricerca WI Cancro, Istituto di Cancerologia, Uniuersita’ di Bologna and ‘Istituto di Istologia ed Ernbriologia Genera/ e, Uniuersita di Bologna, Bologna (Italy) (Received 27 January 1992) (Revision received 9 April 1992) (Accepted 13 April 1992) zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Summary Introduction zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPO By using in vitro two-stage BALB/c 3T3 cell transformation assay, we have tested the effect of promoting tretztment with tetradecanoyl- phorbol acetate (TPA) on transformation in- duced by 1,1,2,2-tetrachloroethane (1,1,2,2- TTCE). Cells were treated with subeffective or transforming concentrations of 1,1,2,2-TTCE in the presence of czn S9-mix activating system, followed by TPA promoting treatment. The transforming activity of 1,1,2,2-TTCE is evi- dent only by reseeding confluent cells and allowing additional rounds of cell rep/kc&ions in the amplification test. Treatment with TPA leads to a marked transformation yield in all plates scored even at the lowest assayed dosage of 1,1,2,2-TKE, without performing amplification of transformation. Key words: 1,1,2,2-tetrachloroethane; cell transformation; BALB/c 3T3; tetradecanoyl- phorbol; initiation; promotion Correspondence to: Sandra Grilli, Istituto di Cancerologia. UniversitA di Bologna, Viale Filopanti 22, 40 126 - Bologna, Italy. Halocompounds are widely produced and utilized chemicals with a high environmental persistence and extensive human exposure [5]. Particularly haloalkanes utilized as sol- vents, chemical intermediates or fumigants, are recognized as being toxic, causing damage to liver both in various animals (rats, mice, dogs) and in humans, to kidney and to other parenchymal tissues [5,17]. Because of con- siderable public concern over the potential hazards associated with exposure to these compounds, a detailed knowledge of the mechanisms of action has become necessary for the assessment of their potential for toxic or carcinogenic activity. Some haloalkanes have been found to exert mutagenic activity in short-term tests in vitro [5,6]. Although several of them which resulted were capable of inducing tumors, particularly hepatocarcinomas, in rodents when tested in long-term assays [5], results from these tests have often been considered insufficient to draw any conclusion on the carcinogenic potency exerted by these compounds. To im- prove knowledge on the role played by haloalkanes in the multistep carcinogenesis, we have utilized the BALB/c 3T3 in vitro cell 0304-3835/92/$05.00 0 1992 Elsevier Scientific Publishers lreland Ltd Printed and Published in Ireland