GROWTH-CHARACTERISTICS OF MURINE-B16 MELANOMA MULTICELLULAR SPHEROIDS- A MODEL FOR INVASION AND EFFECTS OF DOXORUBICIN TREATMENTS

Multicellular spheroids, derived from murine B16 melanoma cells, showe d unique growth characteristics: when they reached about 500 mum in di ameter, their morphology changed rapidly and they became amoeba-Like i rregular-shaped aggregates. This morphological characteristic closely resembled that of invasive cancer, and may serve as a model for local invasion. To test the possibility that the changes mentioned above can be inhibited by a drug, spheroids were treated with 0.8 mug/ml of dox orubicin for one hour and their morphology was observed temporally. Al though this concentration of the drug decreased the survival of the me lanoma cells in monolayer to about 10(-3), the growth was not delayed nor were the 'invasion''-like changes inhibited in the spheroids. We b elieve this system of multicellular spheroids is a useful model to stu dy the mechanisms of tumour invasion, although doxorubicin could not i nhibit ''invasion''-like changes in this system.