Bifunctional chimeric SuperCD suicide gene -YCD: YUPRT fusion is highly effective in a rat hepatoma model

Figure 1 Mode of action of SuperCD (YCD::YUPRT) fusion. Panel A: Schematic representation of biological pathways resulting in cytotoxicity following cytosine deaminase/uracil phosphoribosyltransferase (UPRT)-mediated toxification of the prodrug 5-FC. 5-FC: 5-fluorocytosine; 5-FU: 5-fluorouracil; 5-FUR: 5-fluorouridine; 5-FUMP: 5-fluorouridine 5'-monophosphate; CD: cytosine deaminase; YUPRT: yeast uracil phosphoribosyltransferase. Panel B: Schematic representation of retroviral vectors used, in which suicide gene expression was placed under the retroviral 5' LTR. Panel C: Western blot detection of suicide gene expression in retrovirally generated stable SuperCD/YCD/BCD-expressing Morris hepatoma (MH) cell lines employing polyclonal rabbit antisera directed against BCD (lanes 1 and 2) and YCD (for detection of both SuperCD and YCD; lanes 3-5). Lane 1: MH naïve cells (negative control); lane 2: MH BCD cells, exhibiting a 48-ku band specific for BCD; lane 3: MH naïve cells (negative control); lane 4: MH YCD cells, exhibiting a 18-ku band specific for YCD; lane 5: MH SuperCD cells, exhibiting a 40-ku band specific for the YCD::YUPRT fusion, i.e. SuperCD. Numbers on the right hand side indicate the sizes of the expected proteins.