Cytotoxicity, cellular uptake and DNA damage by daunorubicin and its new analogues with modified daunosamine moiety

Abstract

Daunorubicin (DRB) and its two analogues containing a trisubstituted amidino group at the C-3' position of the daunosamine moiety have been compared regarding their cytotoxic activity, cellular uptake, subcellular localization and DNA damaging properties. An analogue containing in the amidino group a morpholine moiety (DRBM) as well as an analogue with a hexamethyleneimine moiety (DRBH), tested against cultured L1210 cells, exhibited lower cytotoxicity then DRB. The decrease of cytotoxic activity was not related to cellular uptake and subcellular localization of drugs. Although all tested drugs were active in the induction of DNA breaks and DNA-protein crosslinks, they differed in the mechanism of induction of DNA lesions. DRB produced DNA breaks mediated solely by topoisomerase II, whereas DRBM and DRBH induced two types of DNA breaks by two separate processes. The first is related to the inhibition of topoisomerase II and the second presumably reflects a covalent binding of drug metabolites to DNA. It is hypothesized that the replacement of the primary amino group (-NH(2)) at the C-3' position of the daunosamine moiety by a trisubstituted amidino group (-N=CH-NRR) may be a route to the synthesis of anthracycline derivatives with enhanced ability to form covalent adducts to DNA.

Actin disruption inhibits endosomal traffic of P-glycoprotein-EGFP and resistance to daunorubicin accumulation

“…However, after 1 h of incubation, daunorubicin was primarily localized in the nucleus (data not shown). This result is consistent with other studies (3,6) and indicates that daunorubicin penetrated the P-gp barrier on the plasma membrane after treatment with actin inhibitors, resulting in more cellular accumulation.…”

Spectroscopic studies of anthracyclines: Structural characterization and in vitro tracking

“…They have a complex mechanism of action, which includes: intercalation into DNA, inhibition of the synthesis of macromolecules, formation of bonds between the nitrogenous bases of DNA, DNA alkylation, DNA crosslinking, inhibition of topoisomerase I and II -key enzymes in DNA synthesis, and formation of free radicals, which damage DNA and lead to lipid peroxidation [1,8]. Initiation of DNA damage through the inhibition of topoisomerase II, leading to the apoptosis, is believed to be a dominant mechanism of therapeutic action of the anthracyclines [8][9][10] as well as of their cardiotoxicity mediated by topoisomerase-IIβ in cardiomyocytes [11]. Topoisomerases are enzymes, which cause the double helix of DNA to be untangled or unwound, a process which is necessary for DNA replication and transcription.…”

“…Chemical structures of these selected derivatives are also presented in Figure 1.A. It has been shown that these new derivatives of anthracyclines exhibit lower toxicity and cardiotoxicity, together with an ability to overcome the barrier of drug resistance in vitro, as well as high anticancer activity in comparison to the parent compounds (DNR, DOX, EDNR and EDOX) [10,20,22]. Another interesting analog of anthracycline antibiotics is a derivative of DNR -oxazolinodaunorubicin (DNR-OXZL) [23].…”

Synthesis of the Sugar Moieties

“…They exerted cytotoxic and antiproliferative activity by inhibition of topoisomerase II and not by covalent binding to DNA [134,135].…”