Carbamoylating activity associated with the activation of the antitumor agent laromustine inhibits angiogenesis by inducing ASK1-dependent endothelial cell death.

Abstract

The anticancer agent 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)-2-[(methylamino)carbonyl]hydrazine (laromustine), upon decomposition in situ, yields methyl isocyanate and the chloroethylating species 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)hydrazine (90CE). 90CE has been shown to kill tumor cells via a proposed mechanism that involves interstrand DNA cross-linking. However, the role of methyl isocyanate in the antineoplastic function of laromustine has not been delineated. Herein, we show that 1,2-bis(methylsulfonyl)-1-[(methylamino)carbonyl]hydrazine (101MDCE), an analog of laromustine that generates only methyl isocyanate, activates ASK1-JNK/p38 signaling in endothelial cells (EC). We have previously shown that ASK1 forms a complex with reduced thioredoxin (Trx1) in resting EC, and that the Cys residues in ASK1 and Trx1 are critical for their interaction. 101MDCE dissociated ASK1 from Trx1, but not from the phosphoserine-binding inhibitor 14-3-3, in whole cells and in cell lysates, consistent with the known ability of methyl isocyanate to carbamoylate free thiol groups of proteins. 101MDCE had no effect on the kinase activity of purified ASK1, JNK, or the catalytic activity of Trx1. However, 101MDCE, but not 90CE, significantly decreased the activity of Trx reductase-1 (TrxR1). We conclude that methyl isocyanate induces dissociation of ASK1 from Trx1 either directly by carbamoylating the critical Cys groups in the ASK1-Trx1 complex or indirectly by inhibiting TrxR1. Furthermore, 101MDCE (but not 90CE) induced EC death through a non-apoptotic (necroptotic) pathway leading to inhibition of angiogenesis in vitro. Our study has identified methyl isocyanates may contribute to the anticancer activity in part by interfering with tumor angiogenesis.

• Authors: Weidong Ji, Mei Yang, Alexandra Praggastis, Yonghao Li, Huanjiao Jenny Zhou, Yun He, Roxanne Ghazvinian, Dylan J Cincotta, Kevin P Rice, Wang Min
• Journal: PloS one (PLoS One) Vol. 9 Issue 7 Pg. e103224 ( 2014) ISSN: 1932-6203 [Electronic] United States
• PMID: 25068797 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)hydrazine
• Antineoplastic Agents
• Carbamates
• Hydrazines
• Isocyanates
• Sulfonamides
• TXN protein, human
• laromustine
• Thioredoxins
• methyl isocyanate
• TXNRD1 protein, human
• Thioredoxin Reductase 1
• Mitogen-Activated Protein Kinase 8
• MAP Kinase Kinase Kinase 5

Topics

• Animals
• Antineoplastic Agents (metabolism, pharmacology)
• Biocatalysis (drug effects)
• Carbamates (metabolism)
• Cattle
• Cell Death (drug effects)
• Cells, Cultured
• Endothelial Cells (drug effects, metabolism, physiology)
• Humans
• Hydrazines (metabolism, pharmacology)
• Immunoblotting
• Isocyanates (metabolism, pharmacology)
• MAP Kinase Kinase Kinase 5 (metabolism)
• Mitogen-Activated Protein Kinase 8 (metabolism)
• Neovascularization, Physiologic (drug effects)
• Signal Transduction (drug effects)
• Sulfonamides (metabolism, pharmacology)
• Thioredoxin Reductase 1 (metabolism)
• Thioredoxins (metabolism)