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.
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.
Tanaka
Hideki
H
Discovery Research Laboratories, Nippon Shinyaku Co. Ltd., Kyoto 601-8550, Japan. hi.tanaka@po.nippon-shinyaku.co.jp
Ohshima
Nobuko
N
Ikenoya
Mami
M
Komori
Kinuyo
K
Katoh
Fumitaka
F
Hidaka
Hiroyoshi
H
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D001597:Benzylidene Compounds / Q000378:metabolism / Q000494:pharmacology; D023081:CCAAT-Binding Factor / Q000378:metabolism*; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D019450:Genes, MDR / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D007624:KB Cells; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D011725:Pyridines / Q000378:metabolism / Q000494:pharmacology
C479799:(E)-4-((2-N-(4-methoxybenzenesulfonyl)amino)stilbazole)1-oxide; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D001597:Benzylidene Compounds; D023081:CCAAT-Binding Factor; D011725:Pyridines; D004317:Doxorubicin