A Nitric Oxide Storage and Transport System That Protects Activated Macrophages from Endogenous Nitric Oxide Cytotoxicity.

Abstract

Nitric oxide (NO) is integral to macrophage cytotoxicity against tumors due to its ability to induce iron release from cancer cells. However, the mechanism for how activated macrophages protect themselves from endogenous NO remains unknown. We previously demonstrated by using tumor cells that glutathione S-transferase P1 (GSTP1) sequesters NO as dinitrosyl-dithiol iron complexes (DNICs) and inhibits NO-mediated iron release from cells via the transporter multidrug resistance protein 1 (MRP1/ABCC1). These prior studies also showed that MRP1 and GSTP1 protect tumor cells against NO cytotoxicity, which parallels their roles in defending cancer cells from cytotoxic drugs. Considering this, and because GSTP1 and MRP1 are up-regulated during macrophage activation, this investigation examined whether this NO storage/transport system protects macrophages against endogenous NO cytotoxicity in two well characterized macrophage cell types (J774 and RAW 264.7). MRP1 expression markedly increased upon macrophage activation, and the role of MRP1 in NO-induced 59Fe release was demonstrated by Mrp1 siRNA and the MRP1 inhibitor, MK571, which inhibited NO-mediated iron efflux. Furthermore, Mrp1 silencing increased DNIC accumulation in macrophages, indicating a role for MRP1 in transporting DNICs out of cells. In addition, macrophage 59Fe release was enhanced by silencing Gstp1, suggesting GSTP1 was responsible for DNIC binding/storage. Viability studies demonstrated that GSTP1 and MRP1 protect activated macrophages from NO cytotoxicity. This was confirmed by silencing nuclear factor-erythroid 2-related factor 2 (Nrf2), which decreased MRP1 and GSTP1 expression, concomitant with reduced 59Fe release and macrophage survival. Together, these results demonstrate a mechanism by which macrophages protect themselves against NO cytotoxicity.

• Authors: Hiu Chuen Lok, Sumit Sahni, Patric J Jansson, Zaklina Kovacevic, Clare L Hawkins, Des R Richardson
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 291 Issue 53 Pg. 27042-27061 (12 30 2016) ISSN: 1083-351X [Electronic] United States
• PMID: 27866158 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Chemical References

• Bronchodilator Agents
• Gstp2 protein, mouse
• Iron Isotopes
• Multidrug Resistance-Associated Proteins
• Propionates
• Protective Agents
• Quinolines
• RNA, Small Interfering
• Nitric Oxide
• verlukast
• Glutathione S-Transferase pi
• Gstp1 protein, mouse
• Glutathione
• multidrug resistance-associated protein 1

Topics

• Animals
• Biological Transport
• Bronchodilator Agents (pharmacology)
• Cells, Cultured
• Glutathione (metabolism)
• Glutathione S-Transferase pi (antagonists & inhibitors, physiology)
• Iron Isotopes (metabolism)
• Macrophage Activation (drug effects)
• Macrophages (drug effects, metabolism, pathology)
• Mice
• Mice, Knockout
• Multidrug Resistance-Associated Proteins (antagonists & inhibitors, physiology)
• Nitric Oxide (metabolism, toxicity)
• Propionates (pharmacology)
• Protective Agents (pharmacology)
• Quinolines (pharmacology)
• RNA, Small Interfering (genetics)