A synthetic dinuclear copper(II) hydrolase and its potential as antitumoral: cytotoxicity, cellular uptake, and DNA cleavage.
We have studied the protonation equilibria of a dicopper(II) complex [Cu(2)(micro-OH)(C(21)H(33)ON(6))](ClO(4))(2).H(2)O, (1), in aqueous solution, its interactions with DNA, its cytotoxic activity, and its uptake in tumoral cells. C(21)H(33)ON(6) corresponds to the ligand 4-methyl-2,6-bis[(6-methyl-1,4-diazepan-6-yl)iminomethyl]phenol. From spectrophotometric data the following pKa values were calculated 3.27, 4.80 and 6.10. Complex 1 effectively promotes the hydrolytic cleavage of double-strand plasmid DNA under anaerobic and aerobic conditions. The following kinetic parameters were calculated k(cat) of 2.73 x 10(-4)s(-1), K(M) of 1.36 x 10(-4)M and catalytic efficiency of 2.01 s(-1)M(-1), a 2.73 x 10(7) fold increase in the rate of the reaction compared to the uncatalyzed hydrolysis rate of DNA. Competition assays with distamycin reveal minor groove binding. Complex 1 inhibited the growth of two tumoral cell lines, GLC4 and K562, with the IC(50) values of 14.83 microM and 34.21 microM, respectively. There is a good correlation between cell growth inhibition and intracellular copper content. When treated with 1, cells accumulate approximately twice as much copper as with CuCl(2). Copper-DNA adducts are formed inside cells when they are exposed to the complex. In addition, at concentrations that compound 1 inhibits tumoral cell growth it does not affect macrophage viability. These results show that complex 1 has a good therapeutic prospect.
Rey
Nicolás A
NA
Department of Chemistry, Universidade Federal de Santa Catarina, Florianópolis SC, Brazil.
Neves
Ademir
A
Silva
Priscila P
PP
Paula
Flávia C S
FC
Silveira
Josianne N
JN
Botelho
Françoise V
FV
Vieira
Leda Q
LQ
Pich
Claus T
CT
Terenzi
Hernán
H
Pereira-Maia
Elene C
EC
D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D003300:Copper; D018736:DNA Adducts / Q000737:chemistry / Q000378:metabolism; D053837:DNA Cleavage / Q000187:drug effects*; D004214:Distamycins / Q000494:pharmacology; D004354:Drug Screening Assays, Antitumor / Q000379:methods; D005260:Female; D006801:Humans; D020014:K562 Cells; D007700:Kinetics; D017737:Macrophages, Peritoneal / Q000378:metabolism; D008297:Male; D051379:Mice; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D009942:Organometallic Compounds / Q000737:chemistry / Q000494:pharmacology*
D000970:Antineoplastic Agents; D018736:DNA Adducts; D004214:Distamycins; D009942:Organometallic Compounds; D003300:Copper; C030000:stallimycin