title: Stimulation of cis-diamminedichloroplatinum(II) accumulation by modulation of passive permeability with genistein: an altered response in accumulation-defective resistant cells.
abstract: The effect of the tyrosine kinase inhibitor genistein on the accumulation of cisplatin (DDP) was investigated in DDP-sensitive and -resistant human 2008 ovarian carcinoma cell lines. DDP accumulation after a 1-h exposure was maximally increased by concurrent 40 micrometer genistein. The maximal stimulation of accumulation was observed after 2 h of total genistein exposure and was 83 +/- 13% (n = 5) higher than controls. With resistant C13(*) cells, however, the stimulation of accumulation was delayed until 4 h and was increased only 46 +/- 18% compared to controls. Revertant RH4 cells that retained the accumulation defect behaved like the C13(*) cells. Genistein stimulated [3H]mannitol accumulation (a marker of passive permeability) by 43 +/- 9% (n = 3) in 2008 cells, and the effect was maximal after 2 h of total genistein exposure. Changes in [3H]mannitol accumulation in 2008 parent cells were highly correlated with DDP accumulation (r = 0.9010). These experiments also revealed that [3H]mannitol accumulation after 2 h in C13(*) cells was reduced 38% compared to 2008 cells, a decrease that reflected the DDP accumulation defect. Fluid-phase pinocytosis determined with lucifer yellow CH as a marker showed no difference between 2008 and C13(*) cells and no effect of genistein. Genistein was demonstrated to clearly inhibit protein-tyrosine phosphorylation initiated by the epidermal growth factor receptor kinase. Differences were noted in the phosphotyrosine pattern between the 2008 and C13(*) cells. Under the conditions that had the maximal effect on DDP accumulation in 2008 cells, genistein decreased the IC50 of DDP 8.2-fold in 2008 cells and 4.7-fold in C13(*) cells. We conclude that: (a) genistein stimulates DDP accumulation by modulating the passive permeability of the plasma membrane; (b) C13(*) cells are less permeable to passively diffusing small molecules, which offers a mechanism for the DDP accumulation defect without invoking carrier proteins; (c) the effect of tyrosine kinase inhibition on passive permeability is altered in C13(*) cells; and (d) pinocytosis contributes insignificantly to DDP accumulation. Genistein, a dietary isoflavone, thus seems to be a promising clinical candidate for combination with DDP.
authors.affiliation: Department of Pharmacology, Georgetown University, Washington, DC 20007, USA.
authors.forename: G
authors.initials: G
authors.lastname: Marverti
authors.forename: P A
authors.initials: PA
authors.lastname: Andrews
mesh_terms: D000970:Antineoplastic Agents / Q000493:pharmacokinetics*; D002463:Cell Membrane Permeability; D002945:Cisplatin / Q000493:pharmacokinetics* / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D019833:Genistein / Q000494:pharmacology*; D006801:Humans; D008353:Mannitol / Q000378:metabolism; D010766:Phosphorylation; D010873:Pinocytosis; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D008353:Mannitol; D014443:Tyrosine; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D002945:Cisplatin