Effects of Secondary Metabolites from the Fungus Septofusidium berolinense on DNA Cleavage Mediated by Human Topoisomerase IIα

Abstract

Two metabolites from the ascomycete fungus Septofusidium berolinense were recently identified as having antineoplastic activity [Ekiz, et al. (2015) J. Antibiot. (Tokyo)]. However, the basis for this activity is not known. One of the compounds [3,6-dihydroxy-2-propylbenzaldehyde (GE-1)] is a hydroquinone and the other [2-hydroxymethyl-3-propylcyclohexa-2,5-diene-1,4-dione (GE-2)] is a quinone. Because some hydroquinones and quinones act as topoisomerase II poisons, the effects of GE-1 and GE-2 on DNA cleavage mediated by human topoisomerase IIα were assessed. GE-2 enhanced DNA cleavage ~4–fold and induced scission with a site specificity similar to that of the anticancer drug etoposide. Similar to other quinone-based topoisomerase II poisons, GE-2 displayed several hallmark characteristics of covalent topoisomerase II poisons, including: 1) the inability to poison a topoisomerase IIα construct that lacks the N-terminal domain; 2) the inhibition of DNA cleavage when the compound was incubated with the enzyme prior to the addition of plasmid, and 3) the loss of poisoning activity in the presence of a reducing agent. In contrast to GE-2, GE-1 did not enhance DNA cleavage mediated by topoisomerase IIα except at very high concentrations. However, the activity and potency of the metabolite were dramatically enhanced under oxidizing conditions. Results suggest that topoisomerase IIα may play a role in mediating the cytotoxic effects of these fungal metabolites.

Over-expression of Topoisomerase II Enhances Salt Stress Tolerance in Tobacco

“…Apart from the role of topoisomerases in resolving problems associated with topological strains, they are being actively studied for their role as target for anticancerous drugs (Vann et al, 2016 ). In plants, most of the work on topoisomerases is focused on their isolation, purification and characterization (Badaracco et al, 1983 ) but their role in conferring abiotic stress tolerance in plants has not been explored.…”

Structural modification of ellipticine derivatives with alkyl groups of varying length is influential on their effects on human DNA topoisomerase II: a combined experimental and computational study

“…Decatenation assays were carried out as described (Vann et al 2016a). Reaction mixtures contained 0.2 µg of kinetoplast DNA (kDNA) from Crithidia fasciculata and 75 nM and human topoisomerase II alfa in a final volume of 20 µL of 50 mM Tris-Cl, pH 8.0, 120 mM KCl, 10 mM MgCl 2 , 0.5 mM ATP, and 0.5 mM dithiothreitol.…”

“…DNA cleavage assays contained 10 nM negatively supercoiled pBR322 DNA and 150 nM human topoisomerase II of either alfa or beta isoforms in a final volume of 20 µL of 10 mM Tris-HCl, pH 7.9, 5 mM MgCl 2 , 100 mM KCl, 0.1 mM EDTA, and 2.5% (v/v) glycerol (Senarisoy et al 2013;Vann et al 2016a). Mixtures were incubated for 6 min at 37°C.…”

“…DNA topoisomerases play fundamental roles in overcoming topological problems of DNA by introducing transient breaks in the duplex during replication, transcription, recombination, and chromosomal segregation (Wang 1971). Given that the inherent functions of topoisomerases are crucial for genomic integrity, the interfere with these enzymes or generating enzyme-mediated DNA damage is an effective strategy in development of chemotherapeutic agents (Coban et al 2008;Gul et al 2009;Senarisoy et al 2013;Ashley and Osheroff 2014;Ketron and Osheroff 2014;Zupkó et al 2014;Vann et al 2016aVann et al , 2016bDelgado et al 2018).…”

Smoothed Potential MD Simulations for Dissociation Kinetics of Etoposide To Unravel Isoform Specificity in Targeting Human Topoisomerase II

“…To date, all clinical TopoII poisons are nonspecific with regard to TopoIIα and TopoIIβ and affect the DNA cleavage activity of both isoforms. ,,− However, the contribution of each isoform to the therapeutic effects of drugs is not well understood. ,− In this regard, both cellular and in vivo studies suggest that TopoIIβ is primarily responsible for generating the breaks in the mixed lineage leukemia ( MLL ) gene that initiate the acute myelogenous leukemias that are associated with etoposide treatment. ,, Strong support for this hypothesis comes from studies with a skin carcinogenesis model, where the incidence of secondary malignancies was curtailed in a TopoIIβ-knockout mouse . Further, TopoIIβ was also related to etoposide-induced DNA sequence rearrangements and double-strand breaks in a murine cell model .…”