Topoisomerase poisoning by the flavonoid nevadensin triggers DNA damage and apoptosis in human colon carcinoma HT29 cells

Abstract

Nevadensin, an abundant polyphenol of basil, is reported to reduce alkenylbenzene DNA adduct formation. Furthermore, it has a wide spectrum of further pharmacological properties. The presented study focuses the impact of nevadensin on topoisomerases (TOPO) in vitro. Considering the DNA-intercalating properties of flavonoids, first, minor groove binding properties (IC50 = 31.63 µM), as well as DNA intercalation (IC50 = 296.91 µM) of nevadensin, was found. To determine potential in vitro effects on TOPO I and TOPO IIα, the relaxation and decatenation assay was performed in a concentration range of 1–500 µM nevadensin. A partial inhibition was detected for TOPO I at concentrations ≥ 100 µM, whereas TOPO IIα activity is only inhibited at concentrations ≥ 250 µM. To clarify the mode of action, the isolating in vivo complex of enzyme assay was carried out using human colon carcinoma HT29 cells. After 1 h of incubation, the amount of TOPO I linked to DNA was significantly increased by nevadensin (500 µM), why nevadensin was characterized as TOPO I poison. However, no effects on TOPO IIα were detected in the cellular test system. As a subsequent cellular response to TOPO I poisoning, a highly significant increase of DNA damage after 2 h and a decrease of cell viability after 48 h at the same concentration range were found. Furthermore, after 24 h of incubation a G2/M arrest was observed at concentrations ≥ 100 µM by flow cytometry. The analysis of cell death revealed that nevadensin induces the intrinsic apoptotic pathway via activation of caspase-9 and caspase-3. The results suggest that cell cycle disruption and apoptotic events play key roles in the cellular response to TOPO I poisoning caused by nevadensin in HT29 cells.

Evaluation of the cytotoxic, anticancer, and genotoxic activities of Acacia nilotica flowers and their effects on N-methyl-N-nitrosourea-induced genotoxicity in mice

“…Unexpectedly, administration of A. nilotica at doses of > 200 mg/kg potentiated the DNA- damaging effect induced by the direct-action alkylating agent MNU in MN and comet assays. These findings can be explained by the fact that many flavonoids intercalate into DNA and inhibit DNA topoisomerases (I and II) by exerting their mutagenic effects [ 44 , 45 ]. This observation directly agreed with previous literature, which showed that some antioxidant compounds with biphasic nature might exert mutagenic and antimutagenic effects depending on the mutagenic agent and test system used [ 46 , 47 ].…”

Metabolic profiling as a powerful tool for the analysis of cellular alterations caused by 20 mycotoxins in HepG2 cells

“… 2017 )), HT-29 (colon carcinoma cells (Müller et al. 2021 )) and HepG2] to cover analytes with no available reference compounds. The integrated peak areas were further processed using Microsoft Excel 2019 (Microsoft Corporation, Redmond, USA).…”

Activating the Hippo pathway by nevadensin overcomes Yap-drived resistance to sorafenib in hepatocellular carcinoma

“…It exhibits many in vitro pharmacological and biological activities such as anti-inflammatory, anti-microbial, and anti-tuberculosis [ 10 , 11 ]. In addition, studies have shown that nevadensin induced the intrinsic apoptosis pathway by interrupting the cell cycle and activating caspase-3 and caspase-9, leading to DNA damage and apoptosis in human colon cancer HT29 cells [ 12 ]. It was also associated with caspase-3-mediated mitochondrial apoptosis in many HCC cells, such as BEL-7404, HepG2, and SMMC-7721 [ 13 , 14 ].…”