Induction of unique structural changes in guanine-rich DNA regions by the triazoloacridone C-1305, a topoisomerase II inhibitor with antitumor activities

We recently reported that the antitumor triazoloacridone, compound C-1305, is a topoisomerase II poison with unusual properties. In this study we characterize the DNA interactions of C-1305 in vitro, in comparison with other topoisomerase II inhibitors. Our results show that C-1305 binds to DNA by intercalation and possesses higher affinity for GC- than AT-DNA as revealed by surface plasmon resonance studies. Chemical probing with DEPC indicated that C-1305 induces structural perturbations in DNA regions with three adjacent guanine residues. Importantly, this effect was highly specific for C-1305 since none of the other 22 DNA interacting drugs tested was able to induce similar structural changes in DNA. Compound C-1305 induced stronger structural changes in guanine triplets at higher pH which suggested that protonation/deprotonation of the drug is important for this drug-specific effect. Molecular modeling analysis predicts that the zwitterionic form of C-1305 intercalates within the guanine triplet, resulting in widening of both DNA grooves and aligning of the triazole ring with the N7 atoms of guanines. Our results show that C-1305 binds to DNA and induces very specific and unusual structural changes in guanine triplets which likely plays an important role in the cytotoxic and antitumor activity of this unique compound

Design and Synthesis of Multi-Functional Ligands through Hantzsch Reaction: Targeting Ca2+ Channels, Activating Nrf2 and Possessing Cathepsin S Inhibitory, and Antioxidant Properties

This work relates to the design and synthesis of a series of novel multi-target directed ligands (MTDLs), i.e., compounds 4a–l, via a convenient one-pot three-component Hantzsch reaction. This approach targeted calcium channel antagonism, antioxidant capacity, cathepsin S inhibition, and interference with Nrf2 transcriptional activation. Of these MTDLs, 4i emerged as a promising compound, demonstrating robust antioxidant activity, the ability to activate Nrf2-ARE pathways, as well as calcium channel blockade and cathepsin S inhibition. Dihydropyridine 4i represents the first example of an MTDL that combines these biological activities.This work was supported by the Regional Council of Franche-Comté (2022Y-13659 and 13660 ACCURATE PROJECT).Peer reviewe

Influence of pH on DEPC reactivity toward a 176 bp DNA fragment incubated in the presence of C-1305 () Experiments were carried out in 10 mM Tris–HCl/NaCl buffer with increasing pH value (ranging from 5

<p><b>Copyright information:</b></p><p>Taken from "Induction of unique structural changes in guanine-rich DNA regions by the triazoloacridone C-1305, a topoisomerase II inhibitor with antitumor activities"</p><p>Nucleic Acids Research 2005;33(18):6034-6047.</p><p>Published online 27 Oct 2005</p><p>PMCID:PMC1270948.</p><p>© The Author 2005. Published by Oxford University Press. All rights reserved</p>55 to 9.0). Control tracks with DNA (D) were added for each pH value and contained no drug. G, guanine track; C, DNA unmodified; D, control DNA. 1, 20–1 and 20 µM C-1305. Optical density analysis of specific drug–DNA interaction sites. () Arrow indicates the position of the band on which the cleavage intensity for each compound was measured by densitometry. The graph represents an increase of the cleavage at guanine site over control/untreated DNA

SPR sensograms () for binding of C-1305 to the GC DNA hairpin oligomer in HBS-EP buffer at 25°C

<p><b>Copyright information:</b></p><p>Taken from "Induction of unique structural changes in guanine-rich DNA regions by the triazoloacridone C-1305, a topoisomerase II inhibitor with antitumor activities"</p><p>Nucleic Acids Research 2005;33(18):6034-6047.</p><p>Published online 27 Oct 2005</p><p>PMCID:PMC1270948.</p><p>© The Author 2005. Published by Oxford University Press. All rights reserved</p> Table () represents equilibrium binding constants of C-1305 and C-1533 to [AT] and [GC] DNA

Absorption () and CD spectra () of C-1533 in the presence of increasing concentration of DNA (calf thymus DNA, poly(dA–dT) and poly(dG–dC))

<p><b>Copyright information:</b></p><p>Taken from "Induction of unique structural changes in guanine-rich DNA regions by the triazoloacridone C-1305, a topoisomerase II inhibitor with antitumor activities"</p><p>Nucleic Acids Research 2005;33(18):6034-6047.</p><p>Published online 27 Oct 2005</p><p>PMCID:PMC1270948.</p><p>© The Author 2005. Published by Oxford University Press. All rights reserved</p> DNA titration of the drug were performed in BPE buffer at pH 7.1. To 1 ml of drug solution at 20 µM for absorption measurement and 50 µM for CD spectra, aliquots of a concentrated DNA solution were added. Vertical arrows indicate the increase of phosphate-DNA/drug ratio

Heme oxygenase-1 inhibits myoblast differentiation by targeting myomirs

AIMS: Heme oxygenase-1 (HMOX1) is a cytoprotective enzyme degrading heme to biliverdin, iron ions, and carbon monoxide, whose expression is induced in response to oxidative stress. Its overexpression has been suggested as a strategy improving survival of transplanted muscle precursors. Results: Here we demonstrated that HMOX1 inhibits differentiation of myoblasts and modulates miRNA processing: downregulates Lin28 and DGCR8, lowers the total pool of cellular miRNAs, and specifically blocks induction of myomirs. Genetic or pharmacological activation of HMOX1 in C2C12 cells reduces the abundance of miR-1, miR-133a, miR-133b, and miR-206, which is accompanied by augmented production of SDF-1 and miR-146a, decreased expression of MyoD, myogenin, and myosin, and disturbed formation of myotubes. Similar relationships between HMOX1 and myomirs were demonstrated in murine primary satellite cells isolated from skeletal muscles of HMOX1(+/+), HMOX1(+/−), and HMOX1(−/−) mice or in human rhabdomyosarcoma cell lines. Inhibition of myogenic development is independent of antioxidative properties of HMOX1. Instead it is mediated by CO-dependent inhibition of c/EBPδ binding to myoD promoter, can be imitated by SDF-1, and partially reversed by enforced expression of miR-133b and miR-206. Control C2C12 myoblasts injected to gastrocnemius muscles of NOD-SCID mice contribute to formation of muscle fibers. In contrast, HMOX1 overexpressing C2C12 myoblasts form fast growing, hyperplastic tumors, infiltrating the surrounding tissues, and disseminating to the lungs. Innovation: We evidenced for the first time that HMOX1 inhibits differentiation of myoblasts, affects the miRNA processing enzymes, and modulates the miRNA transcriptome. Conclusion: HMOX1 improves the survival of myoblasts, but concurrently through regulation of myomirs, may act similarly to oncogenes, increasing the risk of hyperplastic growth of myogenic precursors. Antioxid. Redox Signal. 16, 113–127