Two ruthenium(III) complexes, namely trans-indazolium[tetrachlorobis(indazole)-
ruthenate(III)], HInd[RuInd2Cl4] and trans-imidazolium[tetrachlorobis(imidazole)-
ruthenate(III)], HIm[RuIm2Cl4] exhibit high anticancer activity in an autochthonous
colorectal carcinoma model in rats. Recently, it has been shown that both complexes bind
specifically to human serum apotransferrin and the resulting adducts have been studied
through spectroscopic and chromatographic techniques with the ultimate goal of preparing
adducts with good selectivity for cancer cells due to the fact that tumour cells express high
amounts of transferrin receptors on their cell surface.In order to investigate whether the cellular uptake of the complexes was mediated by
apotransferrin or transferrin, we compared the antiproliferative efficacy of
HInd[RuInd2Cl4] and HIm[RuIm2Cl4] with its apotransferrin- and transferrin-bound form
in the human colon cancer cell line SW707 using the microculture tetrazolium test (MTT).Our results show that especially the transferrin-bound forms exhibit high antiproliferative
activity, which exceeds that of the free complex, indicating that this protein can act as a
carrier of the ruthenium complexes into the tumor cell.
