EF24, a novel curcumin analog, disrupts the microtubule cytoskeleton and inhibits HIF-1.
Curcumin, the yellow pigment of the spice turmeric, has emerged as a promising anticancer agent due to its antiproliferative and antiangiogenic properties. However, the molecular mechanism of action of this compound remains a subject of debate. In addition, curcumin's low bioavailability and efficacy profile in vivo further hinders its clinical development. This study focuses on the mechanism of action of EF24, a novel curcumin analog with greater than curcumin biological activity and bioavailability, but no increased toxicity. Treatment of MDA-MB231 breast and PC3 prostate cancer cells with EF24 or curcumin led to inhibition of HIF-1alpha protein levels and, consequently, inhibition of HIF transcriptional activity. This drug-induced HIF inhibition occurred in a VHL-dependent but proteasome-independent manner. We found that, while curcumin inhibited HIF-1alpha gene transcription, EF24 exerted its activity by inhibiting HIF-1alpha posttranscriptionally. This result suggested that the two compounds are structurally similar but mechanistically distinct. Another cellular effect that further differentiated the two compounds was the ability of EF24, but not curcumin, to induce microtubule stabilization in cells. EF24 had no stabilizing effect on tubulin polymerization in an in vitro assay using purified bovine brain tubulin, suggesting that the EF24-induced cytoskeletal disruption in cells may be the result of upstream signaling events rather than EF24 direct binding to tubulin. In summary, our study identifies EF24 as a novel curcumin-related compound possessing a distinct mechanism of action, which we believe contributes to the potent anticancer activity of this agent and can be further exploited to investigate the therapeutic potential of EF24.
Thomas
Shala L
SL
Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia, USA.
Zhong
Diansheng
D
Zhou
Wei
W
Malik
Sanna
S
Liotta
Dennis
D
Snyder
James P
JP
Hamel
Ernest
E
Giannakakou
Paraskevi
P
D000970:Antineoplastic Agents / Q000494:pharmacology; D001597:Benzylidene Compounds / Q000494:pharmacology*; D015687:Cell Hypoxia / Q000187:drug effects / Q000235:genetics; D003474:Curcumin / Q000031:analogs & derivatives* / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects*; D004353:Drug Evaluation, Preclinical; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D034261:Epothilones / Q000627:therapeutic use; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D008870:Microtubules / Q000187:drug effects* / Q000378:metabolism; D008938:Mitosis / Q000187:drug effects; D009369:Neoplasms / Q000473:pathology; D017239:Paclitaxel / Q000627:therapeutic use; D010881:Piperidones / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects / Q000378:metabolism; D014407:Tumor Cells, Cultured; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000378:metabolism
C524042:3,5-bis(2-fluorobenzylidene)piperidin-4-one; D000970:Antineoplastic Agents; D001597:Benzylidene Compounds; D034261:Epothilones; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D010881:Piperidones; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D046988:Proteasome Endopeptidase Complex; C497446:VHL protein, human; D003474:Curcumin; D017239:Paclitaxel