Apoptosis and cell growth arrest in A375 human melanoma cells by diorganotin(IV) and triorganotin(IV) complexes of [meso-Tetra(4-sulfonatophenyl)porphine]manganese(III)chloride

In previous studies we have demonstrated that two derivatives of meso-Tetra(4-sulfonatophenyl)porphine (TPPS), (Bu2Sn)2TPPS and (Bu3Sn)4TPPS, cause apoptotic death of A375 melanoma cells and, at lower concentrations, arrest of cell proliferation. In the present study, we examined if the manganese metal inside the porphyrin cavity could improve the efficacy of this class of compounds. Thus, [meso-Tetra(4-sulfonatophenyl)porphine]Mn(III)Cl (=MnTPPS) derivatives, namely (Me2Sn)2MnTPPS, (Bu2Sn)2MnTPPS, (Me3Sn)4MnTPPS and (Bu3Sn)4MnTPPS, were tested on the A375 human melanoma cell line. A cytotoxicity assay showed that (Bu2Sn)2MnTPPS and (Bu3Sn)4MnTPPS werehighly cytotoxic by inducing apoptosis in melanoma cells, as shown by DNA fragmentation analysis and by apoptoticnuclei fluorescence, and when used at lower concentrations, they affected only cellular proliferation. An arrest of cell proliferation was also observed with (Me3Sn)4MnTPPS, but at the highest concentrations used. Moreover, the lowerconcentration of (Bu3Sn)4MnTPPS induced a change in cell morphology, from a polygonal to an elongated and spindle-shaped phenotype, likewise to its cognate (Bu3Sn)4TPPS, previously tested. Western blotting analysis showed indeedthat both tributyltin compounds, i.e. (Bu3Sn)4MnTPPS and (Bu3Sn)4TPPS, lowered levels of the major proteins involvedin tumorigenesis: ß-catenin, c-myc and snail. We also demonstrated that all compounds entered the cells and localized inthe nuclei. In conclusion, our results show that, in spite of the Mn(III) metal introduction, the butyl derivatives always have a higher efficacy than methyl derivatives, and the tributyltincompounds in particular have an interesting effect in vitro on A375 cell proliferation.