Developing an anticancer copper(II) pro-drug based on the nature of cancer cell and human serum albumin carrier IIA subdomain: mouse model of breast cancer

Abstract

Human serum albumin (HSA)-based drug delivery systems are promising for improving delivery efficiency, anticancer activity and selectivity of anticancer agents. To rationally guide to design HSA carrier for anticancer metal agent, we built a breast mouse model on developing anti-cancer copper (Cu) pro-drug based on the nature of IIA subdomain of HSA carrier and cancer cells. Thus, we first synthesized a new Cu(II) compound derived from tridentate (E)-N'-(5-bromo-2-hydroxybenzylidene)benzohydrazide Schiff base ligand (HL) containing 2 potential leaving groups [indazole (Ind) and NO3−], namely, [Cu(L)(Ind)NO3]. Structural analysis of the HSA complex showed that Cu(L)(Ind)(NO3) could bind to the hydrophobic pocket of the HSA IIA subdomain. Lys199 and His242 coordinate with Cu2+ by replacing the indazole and NO3 ligands of [Cu(L)(Ind)NO3]. The release behavior of the Cu compound from the HSA complex is different at different pH levels. [Cu(L)(Ind)NO3] can enhance cytotoxicity by 2 times together with HSA specifically in cancer cells but has no such effect on normal cells in vitro. Importantly, our in vivo results showed that the HSA complex displayed increased selectivity and capacity to inhibit tumor growth and was less toxic than [Cu(L)(Ind)NO3] alone.

The Sub‐picomolar Cu2+ Dissociation Constant of Human Serum Albumin

“…This is one log unit higher than previously determined by using the competitive ligand nitrilotriacetic acid (NTA) . The most likely reason for this discrepancy is the omission of ternary Cu(NTA)(N Im ) complexes formed with surface histidine residues of HSA . The value of c is also closer to the conditional constants we calculated from potentiometric data of N‐terminal peptides DAH‐NH 2 (log c =13.7) and DAHK‐NH 2 (log c =13.8) …”

“…On the other hand, reduction rates depend not only on redox potential but also the structure of the copper‐bound protein in each oxidation state, and presently the structural reorganisation and intermediates required to achieve a Cu + state remain unclear. The accessibility of a Cu + site might determine the origin of the “ascorbate oxidase” activity and ROS production observed for both Cu(BSA) and Cu(HSA) . Reduction of Cu(HSA) by ascorbate has recently been proposed as a possible pathway for extracellular Cu + acquisition by hCtr1, bypassing the need for Cu 2+ transfer to the N‐terminal site of hCtr1 prior to reduction .…”

“…The accessibility of a Cu + site might determine the origin of the “ascorbate oxidase” activity and ROS production observed for both Cu(BSA) and Cu(HSA) . Reduction of Cu(HSA) by ascorbate has recently been proposed as a possible pathway for extracellular Cu + acquisition by hCtr1, bypassing the need for Cu 2+ transfer to the N‐terminal site of hCtr1 prior to reduction . In view of the relatively low value of log c =10.2±0.1 measured for an N‐terminal model peptide in 50 m m HEPES buffer at pH 7.4, how the extracellular domain of hCtr1 would acquire Cu + from HSA remains unclear.…”

HSA-based multi-target combination therapy: regulating drugs’ release from HSA and overcoming single drug resistance in a breast cancer model

“…Thus, how to rationally construct HSA-based multi-drug delivery systems based on the nature of HSA is a challenge. While we can design pro-drugs with groups reacting to special residues of HSA, such as cysteine and lysine, we can form the HSA complex with drugs that directly bind to HSA (Stehle et al., 1997 ; Kratz, 2007 ; Kratz, 2008 ; Hanif et al., 2012 ; Gou et al., 2015a ; Gou et al., 2016a , b ; Qi et al., 2016a ). HSA has three main binding sites for various kinds of endogenous and exogenous compounds: site 1 in the IIA sub-domain, site 2 in the IIIA sub-domain, and site 3 in the IB sub-domain (Zsila, 2013 ).…”

Copper(ii) complexes based on quinoline-derived Schiff-base ligands: synthesis, characterization, HSA/DNA binding ability, and anticancer activity

“…The binding ability of anticancer agents with HSA affects their distribution, uptake, transfer, metabolism and mechanism of action toward cancer cells. [44][45][46] First, we studied the nature of the C1-C3 binding with HSA using fluorescence and the UV-vis absorption method.…”