Effect of tumor dissaggregation on results of in vitro cell survival assay after in vivo treatment of the EMT-6 tumor: x-rays, cyclophosphamide, and bleomycin.

EMT-6 tumors were treated in vivo with 300 kVp X-rays, cyclophosphamide, or bleomycin. Tumor cell suspensions were prepared by digesting tumors with trypsin or a collagenase-deoxyribonuclease-pronase cocktail, and cells were plated in vitro for determination of fractional cell survival. Cell survival after X-rays was identical for the two disaggregation methods. Trypsin-derived cells were far more sensitive to bleomycin but less sensitive to cyclophosphamide than those prepared with the mixed enzyme cocktail. Interaction of drug produced and enzyme caused damage was the probable cause for these discrepancies. The nature of the interaction may be drug specific and therefore unpredictable. The results were unlikely to be due to different nonrepresentative tumor cell samples being produced by the two digestion methods, because the X-ray cell survival curves were so similar for the two products.