Effect of retinoic acid and its complexes with transition metals on human bladder cancer cell line EJ in vitro

The aim of this study was to investigate the effect of retinoic acid (RA) and its complexes with transition metals on the bladder cancer cell line EJ. Retinoic acid complexes with transition metals Cu, Co, Zn, and Ni were prepared. Cell proliferation was tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in the presence of RA or its complexes with transition metals Cu, Co, Zn, and Ni ¿Cu(RA)2.3H2O, Co(RA)2.3H2O, Zn(RA)2.4H2O, and Ni(RA)2.3H2O¿. Colony formation in soft agar culture, A agglutination reaction, and lactic acid dehydrogenase isoenzyme assay were performed in the cells treated with these drugs to estimate the induced differentiation. p53 or c-Ha-ras expression in drug-treated cells was assayed by ABC immunocytochemistry technique. The results demonstrate that EJ cells treated with the drugs become less confluent and tend to exhibit normal characteristics. Although RA and its complexes showed inhibition to proliferation of EJ cells at the concentrations of 10(-6) mmol/l, the inhibition induced by Ni(RA)2.3H2O was much more marked than that by RA. EJ cells were growth inhibited by RA or Ni(RA)2.3H2O from 48 to 96 h at the concentration of 10(-8) mol/l. The levels of LDH4 and LDH5 in the cells were greatly increased by RA. Nevertheless, Ni(RA)2.3H2O did not affect LDH isoenzyme in EJ cells. The number of colony formations of EJ cells in soft agar culture was decreased by RA or Ni(RA)2.3H2O. The percentage of colony formation in soft agar culture was much lower in EJ cells treated with Ni(RA)2.3H2O than with RA. The required concentration of A agglutination reaction was more increased for EJ cells treated with RA or Ni(RA)2.3H2O than for the control and was further increased in cells treated with Ni(RA)2.3H2O. Mutant p53 expression was more decreased in the EJ cells treated with RA or Ni(RA)2.3H2O than in the control. Although RA at the concentration of 10(-6) mmol/l caused lower p21 expression, Ni(RA)2.3H2O did not affect p21 expression in EJ cells. Therefore, RA and its transition metal complexes have a potential use in the treatment of bladder cancer.