The In Vitro and In Vivo Activity of the Microtubule Disruptor STX140 Is Mediated by Hif-1 Alpha and CAIX Expression.

Abstract

Tumor neo-angiogenesis is regulated, in part, by the hypoxia-inducible gene HIF1. Evidence suggests HIF1 associates with polymerized microtubules and traffics to the nucleus. This study investigated the role of HIF1 in mediating the antitumor activity of two steroid-based sulfamate ester microtubule disruptors, STX140 and STX243, in vitro and in vivo. The effects of STX140, STX243 and the parental compound 2-methoxyestradiol (STX66) on HIF1α and HIF2α protein expression were assessed in vitro in MCF-7 and MDA-MB-231 cells cultured under hypoxia. More pertinently, their effects were examined on HIF1-regulated genes in vivo in mice bearing MCF-7 or MDA-MB-231 tumors. The level of mRNA expression of vascular endothelial growth factor (VEGF), glucose transporter 1 (GLUTI), phosphoglycerate kinase (PGK), ATP-binding cassette sub-family B member 1 (ABCB1) and carbonic anhydrase IX (CAIX) was quantified by Real-time Polymerase Chain Reaction (RT-PCR). Despite inhibiting nuclear HIF1α protein accumulation under hypoxia in vitro, STX140 and STX243 did not significantly regulate the expression of four out of five HIF1α-regulated genes in vitro and in vivo. Only CAIX mRNA expression was down-regulated both in vitro and in vivo. Immunoblot analysis showed that STX140 and STX243 reduced CAIX protein expression in vitro. These compounds had no effect on HIF2α translocation. The potential for inhibition of CAIX by STX140 and STX243 was examined by docking the ligands to the active site in comparison with a known sulfamate-based inhibitor. Microtubule disruption and antitumor activity of STX140 and STX243 is most likely HIF1-independent and may, at least in part, be mediated by inhibition of CAIX expression and activity.

• Authors: Chloe Stengel, Simon P Newman, Mathew P Leese, Mark P Thomas, Barry V L Potter, Michael J Reed, Atul Purohit, Paul A Foster
• Journal: Anticancer research (Anticancer Res) Vol. 35 Issue 10 Pg. 5249-61 (Oct 2015) ISSN: 1791-7530 [Electronic] Greece
• PMID: 26408684 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Chemical References

• 2-ethyloestradiol-bis-sulfamate
• 2-methoxyestradiol-3,17-O,O-bis(sulfamate)
• Antigens, Neoplasm
• Estrenes
• HIF1A protein, human
• Hypoxia-Inducible Factor 1, alpha Subunit
• Sulfonic Acids
• Tubulin Modulators
• Estradiol
• CA9 protein, human
• Carbonic Anhydrase IX
• Carbonic Anhydrases

Topics

• Animals
• Antigens, Neoplasm (genetics)
• Carbonic Anhydrase IX
• Carbonic Anhydrases (genetics)
• Cell Hypoxia (drug effects)
• Cell Line, Tumor
• Estradiol (administration & dosage, analogs & derivatives, pharmacology)
• Estrenes (administration & dosage, pharmacology)
• Female
• Gene Expression Regulation, Neoplastic (drug effects)
• Humans
• Hypoxia-Inducible Factor 1, alpha Subunit (metabolism)
• MCF-7 Cells
• Mammary Neoplasms, Experimental (drug therapy, genetics, metabolism)
• Mice
• Molecular Docking Simulation
• Sulfonic Acids (administration & dosage, pharmacology)
• Tubulin Modulators (administration & dosage, pharmacology)
• Xenograft Model Antitumor Assays