HMN-176, an active metabolite of the synthetic antitumor agent HMN-214, restores chemosensitivity to multidrug-resistant cells by targeting the transcription factor NF-Y

• Published in: Cancer research (Chicago, Ill.) Ill.), 2003-10, Vol.63 (20), p.6942-6947
• Main Authors: Tanaka, Hideki, Ohshima, Nobuko, Ikenoya, Mami, Komori, Kinuyo, Katoh, Fumitaka, Hidaka, Hiroyoshi
• Format: Article
• Language: English
• Subjects: ATP-Binding Cassette, Sub-Family B, Member 1 - antagonists & inhibitors; ATP-Binding Cassette, Sub-Family B, Member 1 - biosynthesis; ATP-Binding Cassette, Sub-Family B, Member 1 - genetics; Benzylidene Compounds - metabolism; Benzylidene Compounds - pharmacology; CCAAT-Binding Factor - metabolism; Cell Line, Tumor; Doxorubicin - pharmacology; Drug Resistance, Multiple; Female; Gene Expression - drug effects; Genes, MDR - drug effects; HeLa Cells; HMN-176; Humans; KB Cells; Ovarian Neoplasms - drug therapy; Ovarian Neoplasms - genetics; Ovarian Neoplasms - metabolism; Protein Binding - drug effects; Pyridines - metabolism; Pyridines - pharmacology
• ISSN: 0008-5472

HMN-176 ((E)-4-[[2-N-[4-methoxybenzenesulfonyl]amino]stilbazole]1-oxide) is an active metabolite of HMN-214 ((E)-4-[2-[2-(N-acetyl-N-[4-methoxybenzenesulfonyl]amino)stilbazole]]1-oxide), which has a potent antitumor activity in mouse xenograft models. In this study, we show that HMN-176 circumvents multidrug resistance in a K2 human ovarian cancer subline selected for Adriamycin resistance (K2/ARS). Upon treatment of K2/ARS cells with 3 microM HMN-176, the GI(50) of Adriamycin for the cells decreased by approximately 50%. To explore the molecular mechanism of this effect, we assessed the expression of the multidrug resistance gene (MDR1), which is constitutive in K2/ARS cells, at both the protein and the mRNA level. Western and reverse transcription-PCR analysis revealed that the expression of MDR1 was significantly suppressed by treatment with HMN-176. Furthermore, when administered p.o., HMN-214 suppressed the expression of MDR1 mRNA in a mouse xenograft model implanted with KB-A.1, an Adriamycin-resistant cell line. Luciferase reporter fusion gene analysis demonstrated that HMN-176 inhibited the Y-box-dependent promoter activity of the MDR1 gene in a dose-dependent manner. Moreover, we show by electrophoretic mobility shift assay that HMN-176 inhibits the binding of NF-Y, which is thought to be an essential factor for the basal expression of MDR1, to its target Y-box consensus sequence in the MDR-1 promoter. Inhibition of MDR-1 expression was achieved with pharmacological concentrations of HMN-176, suggesting that HMN-176 may act by two different mechanisms-cytotoxicity and MDR1 down-regulation-simultaneously. The data presented strongly suggest that the antitumor mechanism of HMN-176 (or its prodrug HMN-214 in vivo) is quite different from those of known antitumor agents.