Hiding in plain sight : optimizing topoisomerase IIα inhibitors into Hsp90β selective binders

Dernovšek, Jaka (author), Zajec, Živa (author), Urbančič, Dunja (author), Jug, Ana (author), Skok, Žiga (author), Ilaš, Janez (author), Zidar, Nace (author), Tomašič, Tihomir (author)

Due to their impact on several oncogenic client proteins, the Hsp90 family of chaperones has been widely studied for the development of potential anticancer agents. Although several Hsp90 inhibitors have entered clinical trials, most were unsuccessful because they induced a heat shock response (HSR). This issue can be circumvented by using isoform-selective inhibitors, but the high similarity in the ATP-binding sites between the isoforms presents a challenge. Given that Hsp90 shares a conserved Bergerat fold with bacterial DNA gyrase B and human topoisomerase IIα, we repurposed our ATP-competitive inhibitors of these two proteins for Hsp90 inhibition. We virtually screened a library of in-house inhibitors and identified eleven hits for evaluation of Hsp90 binding. Among these, compound 11 displayed low micromolar affinity for Hsp90 and demonstrated a 12-fold selectivity for Hsp90β over its closest isoform, Hsp90α. Out of 29 prepared analogs, 16 showed a preference for Hsp90β over Hsp90α. Furthermore, eleven of these compounds inhibited the growth of several cancer cell lines in vitro. Notably, compound 24e reduced intracellular levels of Hsp90 client proteins in MCF-7 cells, leading to cell cycle arrest in the G0/G1 phase without inducing HSR. This inhibitor exhibited at least a 27-fold preference for Hsp90β and was selective against topoisomerase IIα, a panel of 22 representative protein kinases, and proved to be non-toxic in a zebrafish larvae toxicology model. Finally, molecular modeling, corroborated by STD NMR studies, and the binding of 24e to the S52A mutant of Hsp90α confirmed that the serine to alanine switch drives the selectivity between the two cytoplasmic isoforms.

• Language: English
• Keywords: cancer, Hsp90, isoform selectivity, topoisomerase II
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FFA - Faculty of Pharmacy
• Publication status: Published
• Publication version: Version of Record
• Year: 2024
• Number of pages: 37 str.
• Numbering: Vol. 280, art. 116934
• PID: 20.500.12556/RUL-163785
• UDC: 615.4:54:616-006-085
• ISSN on article: 0223-5234
• DOI: 10.1016/j.ejmech.2024.116934
• COBISS.SI-ID: 210758915
• Publication date in RUL: 10.10.2024

Record is a part of a journal

• Title: European journal of medicinal chemistry
• Shortened title: Eur. j. med. chem.
• Publisher: Elsevier
• ISSN: 0223-5234
• COBISS.SI-ID: 25429760

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: Hsp90, izoformna selektivnost, topoizomeraza II, rak, medicina, farmacevtska kemija