New Insights into the Mechanism of the DNA/Doxorubicin Interaction

Abstract

Doxorubicin (DOX) is an important anthracycline antibiotic whose intricate features of binding to DNAs, not yet fully understood, have been the object of intense debate. The dimerization equilibrium has been studied at pH = 7.0, I = 2.5 mM, and T = 25 °C. A thermodynamic and kinetic study of the binding of doxorubicin to DNA, carried out by circular dichroism, viscometry, differential scanning calorimetry, fluorescence, isothermal titration calorimetry, and T-jump relaxation measurements, has enabled us to characterize for the first time two different types of calf thymus DNA (ctDNA)/DOX complexes: PD1 for C(DOX)/C(DNA) < 0.3, and PD2 for higher drug content. The nature of the PD1 complex is described better in light of the affinity of DOX with the synthetic copolymers [poly(dA-dT)]2 and [poly(dG-dC)]2. The formation of PD1 has been categorized kinetically as a two-step mechanism in which the fast step is the groove binding in the AT region, and the slow step is the intercalation into the GC region. This bifunctional nature provides a plausible explanation for the high PD1 constant obtained (K1 = 2.3 × 10(8) M(-1)). Moreover, the formation of an external aggregate complex ctDNA/DOX (PD2) at the expense of PD1, with K2 = 9.3 × 10(5) M(-1), has been evinced.

Studying non-covalent drug–DNA interactions

“…Various thermodynamic parameters of the interaction are easily obtained directly or indirectly and the mechanism can be easily elucidated. ITC measures the heat absorbed or released during the interaction and calculates various parameters like binding sites (n), association constant (K), change in enthalpy (DH) and change in entropy (DS) [13,[66][67][68], which are used to decipher the binding interaction and binding mode. For example, a large negative enthalpy of binding along with positive entropy is typical for an interaction of small molecule with DNA [69].…”

Polyethylene glycol gold-nanoparticles: Facile nanostructuration of doxorubicin and its complex with DNA molecules for SERS detection

“…The multifunctional doxorubicin (DOX) conjugated AuNPs (DOX-AuNPs) may also be used to improve imaging contrast for photothermal cancer therapy 24 . Up to now DOX (figure 1) has been considered as an effective anticancer drug and its activity is apparently related to the direct interactions with dsDNA 25,26 , Therefore DOX is an inhibitor of the topoisomerase II and can inhibit DNA duplication and transcription to mRNA 27 . DOX-AuNPs facilitate intracellular drug delivery overcoming multidrug resistance in cancer cells 28 .…”

Engineering Biomaterial–Drug Conjugates for Local and Sustained Chemotherapeutic Delivery

“…A two-step mechanism has been proposed where DOX rapidly binds to the DNA groove via electrostatic interaction 55,56 followed by slow interchelation of the aromatic DOX core into the GC sequence. 55 Dong et al developed a pH/enzyme responsive delivery system using the DNA/DOX complex. 57 The DNA/DOX complex was combined with cationic gelatin (CPX1).…”