Morten Busk, Peter P Eggertsen, Jens Overgaard, Michael R Horsman, Thomas Tørring, Kristian M Jacobsen, Thomas B Poulsen
{"title":"<i>In Vitro</i> Characterization of the Bacteria-derived Hypoxia-selective Cytotoxin BE-43547.","authors":"Morten Busk, Peter P Eggertsen, Jens Overgaard, Michael R Horsman, Thomas Tørring, Kristian M Jacobsen, Thomas B Poulsen","doi":"10.21873/anticanres.16735","DOIUrl":null,"url":null,"abstract":"<p><strong>Background/aim: </strong>Hypoxia-activated pro-drugs, such as TH-302, may kill hypoxic treatment-resistant tumor cells, but have failed in clinical trials. This may be related to variable levels of drug-activating reductases. Compounds such as bacteria-derived BE-43547, which target hypoxic cells independently of reductases, may be beneficial. This study characterized the in vitro potency and hypoxia selectivity of BE-43547 and TH-302.</p><p><strong>Materials and methods: </strong>Tumor cells were exposed to different oxygenation levels in the presence/absence of drug, and survival was quantified using total cell number (BE-43547) or clonogenic survival (BE-43547 and TH-302) assays. Half-maximal inhibitory concentration (IC<sub>50</sub>) values and the hypoxia-cytotoxicity-ratio (HCR: normoxic IC<sub>50</sub>/hypoxic IC<sub>50</sub>) were determined from dose-response curves. Finally, both drugs were tested in spheroids exposed to 20% or 0% O<sub>2</sub> for 24 h followed by assessment of clonogenic survival.</p><p><strong>Results: </strong>BE-43547 was highly potent and displayed little inter-cell line variability. Strongly enhanced cytotoxicity was observed under oxygen-restricted conditions with HCR's of ~100 and ~20 after 24 h of treatment with 0 or 0.5% O<sub>2</sub>, respectively. Reducing treatment time somewhat reduced hypoxia selectivity. Hypoxia selectivity was observed regardless of whether the drug was added before or during the hypoxic challenge. TH-302 IC<sub>50</sub> values varied 10-fold under oxic conditions, whereas those of the anoxic-to-normoxic HCR varied from 15 to 88. Both BE-43547 and TH-302 were unable to completely sterilize anoxic incubated spheroids.</p><p><strong>Conclusion: </strong>BE-43547 is highly hypoxia-selective, and unlike TH-302, displayed minimal variability between cell lines, suggesting that BE-43547 targets a fundamental feature/target that is only present, or of survival importance, during hypoxia. Spheroid experiments suggested inadequate tissue penetrability, which may be overcome by designing novel drug analogs.</p>","PeriodicalId":8072,"journal":{"name":"Anticancer research","volume":"43 12","pages":"5319-5329"},"PeriodicalIF":1.6000,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Anticancer research","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.21873/anticanres.16735","RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"ONCOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Background/aim: Hypoxia-activated pro-drugs, such as TH-302, may kill hypoxic treatment-resistant tumor cells, but have failed in clinical trials. This may be related to variable levels of drug-activating reductases. Compounds such as bacteria-derived BE-43547, which target hypoxic cells independently of reductases, may be beneficial. This study characterized the in vitro potency and hypoxia selectivity of BE-43547 and TH-302.
Materials and methods: Tumor cells were exposed to different oxygenation levels in the presence/absence of drug, and survival was quantified using total cell number (BE-43547) or clonogenic survival (BE-43547 and TH-302) assays. Half-maximal inhibitory concentration (IC50) values and the hypoxia-cytotoxicity-ratio (HCR: normoxic IC50/hypoxic IC50) were determined from dose-response curves. Finally, both drugs were tested in spheroids exposed to 20% or 0% O2 for 24 h followed by assessment of clonogenic survival.
Results: BE-43547 was highly potent and displayed little inter-cell line variability. Strongly enhanced cytotoxicity was observed under oxygen-restricted conditions with HCR's of ~100 and ~20 after 24 h of treatment with 0 or 0.5% O2, respectively. Reducing treatment time somewhat reduced hypoxia selectivity. Hypoxia selectivity was observed regardless of whether the drug was added before or during the hypoxic challenge. TH-302 IC50 values varied 10-fold under oxic conditions, whereas those of the anoxic-to-normoxic HCR varied from 15 to 88. Both BE-43547 and TH-302 were unable to completely sterilize anoxic incubated spheroids.
Conclusion: BE-43547 is highly hypoxia-selective, and unlike TH-302, displayed minimal variability between cell lines, suggesting that BE-43547 targets a fundamental feature/target that is only present, or of survival importance, during hypoxia. Spheroid experiments suggested inadequate tissue penetrability, which may be overcome by designing novel drug analogs.
期刊介绍:
ANTICANCER RESEARCH is an independent international peer-reviewed journal devoted to the rapid publication of high quality original articles and reviews on all aspects of experimental and clinical oncology. Prompt evaluation of all submitted articles in confidence and rapid publication within 1-2 months of acceptance are guaranteed.
ANTICANCER RESEARCH was established in 1981 and is published monthly (bimonthly until the end of 2008). Each annual volume contains twelve issues and index. Each issue may be divided into three parts (A: Reviews, B: Experimental studies, and C: Clinical and Epidemiological studies).
Special issues, presenting the proceedings of meetings or groups of papers on topics of significant progress, will also be included in each volume. There is no limitation to the number of pages per issue.