Hypoxia is an extremely important condition for tumor metabolism. The cellular response to hypoxia is mainly mediated by the hypoxia-inducible factor (HIF) family of transcription factors, which regulate the expression of multiple genes engaged in different processes that lead to adaptation, progression and drug resistance of cancers. CA9 (CA IX) is a gene controlled by HIF-1α and is one of two tumor-associated carbonic anhydrase isoenzymes known. We aimed to obtain water-soluble derivatives of quinoxaline 1,4-dioxides targeting HIF-1α/CA9 path in breast cancer cells.
New 6(7)-amino derivatives were synthesized from corresponding 7- or/and 6-halogenoquinoxaline-2-carbonitrile 1,4-dioxides by the substitution of halogen atom by cyclic diamines. The antiproliferative activity of 6(7)-aminoquinoxaline-2-carbonitrile 1,4-dioxides was evaluated in normoxia and hypoxia. HIF-1α and CA9 expression was assessed by immunoblotting.
All synthetized derivatives quinoxaline-2-carbonitrile 1,4-dioxides have higher cytotoxicity and hypoxia-selectivity against breast cancer cell lines (MCF-7, MDAMB-231) than reference drug tirapazamine. Furthermore, the cytotoxicity of obtained compounds highly increased under hypoxic conditions. The most hypoxia-selective derivatives were congeners bearing diamine in position 7 which had hypoxic cytotoxicity ratio (HCR) values ranges from 20 to 42. The most potent derivative LCTA-2647 in hypoxia had IC50 value lower than 0.2 μM with HCR 37. Compounds LCTA-2424 and LCTA-2647 showed inhibitory effects on HIF-1α and CA9 expression in MCF-7 breast cancer cells.
Novel derivatives of 7-amino-quinoxaline-2-carbonitrile 1,4-dioxide showed high antiproliferative potency and hypoxia-selectivity. Lead compounds caused HIF-1α-CA9 inhibitory effects are considered as promising agents for tumors, including those with hypoxic areas.
Gause Institute of New Antibiotics.
The experiments were supported by Russian Foundation for Basic Research (RFBR) grants 18-53-34005 (chemistry) and 18-015-00422 (biology).
G.I. Buravchenko: Research grant/Funding (institution), Travel/Accommodation/Expenses: Gause Institute of New Antibiotics. All other authors have declared no conflicts of interest.