Rational design of gold(III)-dithiocarbamato peptidomimetics for the targeted anticancer chemotherapy.

As a further extension of our research work focusing on the development of gold(III)-dithiocarbamato dtc derivatives of oligopeptides as potential anticancer agents, complexes [Au(III)X(2)(dtc-Sar-L-Ser(t-Bu)-O(t-Bu))] (X=Br (1a)/Cl (1b)), [Au(III)X(2)(dtc-AA-Aib(2)-O(t-Bu))] (AA=Sar (sarcosine, N-methylglycine), X=Br (2a)/Cl (2b); AA=D,L-Pro, X=Br (3a)/Cl (3b)), [Au(III)X(2)(dtc-Sar-Aib(3)-O(t-Bu))] (X=Br (4a)/Cl (4b)), and [Au(III)X(2)(dtc-Sar-Aib(3)-Gly-OEt)] (X=Br (5a)/Cl (5b)) (Aib = "alpha"-aminoisobutyric acid, 2-methylalanine) were designed to obtain metal-based peptidomimetics that may specifically target two peptide transporters (namely, PEPT1 and PEPT2) upregulated in several human tumor cells. All the compounds were characterized by means of FT-IR and mono- and multidimensional NMR spectroscopy. According to in vitro cytotoxicity studies, complex [Au(III)Cl(2)(dtc-D,L-Pro-Aib(2)-O(t-Bu))] (3b) turned out to be the most effective toward the four human tumor cell lines evaluated (PC3, 2008, C13, and L540), for which the IC(50) values were lower than cisplatin. Remarkably, it showed no cross-resistance with cisplatin itself and was proved to inhibit tumor cell proliferation by inducing almost exclusively late apoptosis/necrosis. Biological results are here reported and discussed in terms of the structure-activity relationship.

Toward the selective delivery of chemotherapeutics into tumor cells by targeting peptide transporters: tailored gold-based anticancer peptidomimetics.

Complexes [Au(III)X(2)(dtc-Sar-AA-O(t-Bu))] (AA = Gly, X = Br (1)/Cl (2); AA = Aib, X = Br (3)/Cl (4); AA = l-Phe, X = Br (5)/Cl (6)) were designed on purpose in order to obtain gold(III)-based anticancer peptidomimetics that might specifically target two peptide transporters (namely, PEPT1 and PEPT2) upregulated in several tumor cells. All the compounds were characterized by means of FT-IR and mono- and multidimensional NMR spectroscopy, and the crystal structure of [Au(III)Br(2)(dtc-Sar-Aib-O(t-Bu))] (3) was solved and refined. According to in vitro cytotoxicity studies, the Aib-containing complexes 3 and 4 turned out to be the most effective toward all the human tumor cell lines evaluated (PC3, DU145, 2008, C13, and L540), reporting IC(50) values much lower than that of cisplatin. Remarkably, they showed no cross-resistance with cisplatin itself and were proved to inhibit tumor cell proliferation by inducing either apoptosis or late apoptosis/necrosis depending on the cell lines. Biological results are here reported and discussed in terms of the structure-activity relationship.