Green fluorescent protein labelling is compatible with multidrug resistant clones in bladder cancer models

Description/Abstract

Laboratory based therapeutic models of human cancers are hampered by the limitations of using monolayer cell cultures and the difficulties of obtaining accurate animal models. We have described previously an in vitro model in which green fluorescent protein (GFP) labelled urothelial cancer cells are grown as three-dimensional tumours on rat bladder explants. Using GFP in this way requires multidrug resistance (MDR) status to be irrelevant to the experiment, despite the vector also coding for antibiotic resistance, as a cell selection mechanism. The issue becomes acute where laboratories (like ours) are specifically interested in MDR. This study compares the intracellular localisation of epirubicin in GFP transfected vs. untransfected clones of the MGH-u1 bladder cancer cell line. Parental and mitomycin-C resistant MGH-u1 urothelial cancer cells were transfected with a commercial GFP vector containing a universal promoter and an antibiotic resistance cassette. The effect of transfection on drug accumulation and distribution in parental and MDR clones was evaluated using confocal imaging of anthracycline accumulation. Transfection of both parental and MDR clones of MGH-u1 cells was stable over many cell divisions as determined by flow cytometry. Lateral transfer of GFP did not occur in co-culture. Co-localisation experiments demonstrated drug partitioning in cells incubated with epirubicin to be characteristic of the MDR status of the clone used. In conclusion, GFP transfected MGH-u1 cells are self-identifying, irrespective of the MDR status of the cells. This widens the scope of complex tumour models in vivo and in vitro.