HIF-1α and AP1 play important roles in hypoxia and activate anti-apoptotic pathways in tumor cells. No dual HIF-1α/AP1 inhibitors currently exist, so targeting these transcriptional factors is promising way to modulate hypoxia signaling in cancer cells. Aim of the study was obtaining and biological evaluation of hypoxia-selective 7-amino-6-halogen-substituted derivatives starting from 6,7-dihalogeno-3-phenylquinoxaline-2-carbonitrile 1,4-dioxides.
A series of 7-amino-6-halogeno-3-phenylquinoxaline-2-carbonitrile 1,4-dioxides was synthesized. Cancer cell lines were purchased from ATCC. The cytotoxic activity of compounds was evaluated in normoxia (21%O2) and hypoxia (1%O2). The cytotoxicity was assessed by MTT test (72 h growth with compounds). HIF-1α and AP1 activity was assessed by reporter analysis.
Synthesis of 7-amino-6-halogen- substituted derivatives starting from 6,7-dihalogeno-3-phenylquinoxaline-2-carbonitrile 1,4-dioxides was carried out. A series was characterized by good solubility in water. Antiproliferative activity was evaluated in vitro on a panel of cancer cell lines including multidrug resistance variants. Novel synthesized compounds demonstrated higher hypoxia selectivity and cytotoxicity compared with tirapazamine. Some of the 7-amino-6-halogeno derivatives were 10-20-fold more potent than the reference drug. Selected 7-amino-6-halogeno derivatives LCTA-2425 and LCTA-2711 inhibited breast cancer cells growth in hypoxia at concentrations lower than 0.6 µM. Compounds LCTA-2711 and LCTA-2425 showed inhibitory effects on HIF-1α- and AP1-dependent luciferase activity, when tirapazamine revealed no potency to block these factors in MCF-7 breast cancer cells under hypoxic conditions.
A series of 7-amino-6-halogeno-3-phenylquinoxaline-2-carbonitrile 1,4-dioxides were more potent than reference drug tirapazamine in all tested cell lines and demonstrated high selectivity in hypoxia. Selected 7-amino-6-halogeno derivatives showed dual inhibitory activity against HIF-1α and AP1 factors, regulating anti-apoptotic pathways in hypoxia. RFBR grants 18-53-34005 (chemistry), 18-015-00422 (biology).
Alexander M. Scherbakov.
Russian Foundation for Basic Research, Grants 18-53-34005 (Chemistry) and 18-015-00422 (Biology).
All authors have declared no conflicts of interest.