Abstract
5'-Βenzylglycinyl-amiloride (UCD38B) and glycinyl-amiloride (UCD74A) are cell-permeant and cell-impermeant derivatives of amiloride, respectively, and used here to identify the cellular mechanisms of action underlying their antiglioma effects. UCD38B comparably kills proliferating and nonproliferating gliomas cells when cell cycle progression is arrested either by cyclin D1 siRNA or by acidification. Cell impermeant UCD74A inhibits plasmalemmal urokinase plasminogen activator (uPA) and the type 1 sodium-proton exchanger with potencies analogous to UCD38B, but is cytostatic. In contrast, UCD38B targets intracellular uPA causing mistrafficking of uPA into perinuclear mitochondria, reducing the mitochondrial membrane potential, and followed by the release of apoptotic inducible factor (AIF). AIF nuclear translocation is followed by a caspase-independent necroptotic cell death. Reduction in AIF expression by siRNA reduces the antiglioma cytotoxic effects of UCD38B, while not activating the caspase pathway. Ultrastructural changes shortly following treatment with UCD38B demonstrate dilation of endoplasmic reticulum (ER) and mitochondrial swelling followed by nuclear condensation within hours consistent with a necroptotic cell death differing from apoptosis and from autophagy. These drug mechanism of action studies demonstrate that UCD38B induces a cell cycle-independent, caspase-independent necroptotic glioma cell death that is mediated by AIF and independent of poly (ADP-ribose) polymerase and H2AX activation.
Publication types
-
Research Support, N.I.H., Extramural
MeSH terms
-
Amiloride / analogs & derivatives*
-
Amiloride / pharmacology*
-
Apoptosis / drug effects
-
Apoptosis / genetics
-
Apoptosis Inducing Factor / genetics
-
Apoptosis Inducing Factor / metabolism*
-
Autophagy / drug effects
-
Autophagy / genetics
-
Caspases / genetics
-
Caspases / metabolism*
-
Cell Cycle / drug effects
-
Cell Cycle / genetics
-
Cell Cycle Checkpoints / drug effects
-
Cell Cycle Checkpoints / genetics
-
Cell Death / drug effects*
-
Cell Death / genetics
-
Cell Line, Tumor
-
Cell Nucleus / genetics
-
Cell Nucleus / metabolism
-
Cell Proliferation / drug effects
-
Cyclin D1 / genetics
-
Cyclin D1 / metabolism
-
Endoplasmic Reticulum / drug effects
-
Endoplasmic Reticulum / metabolism
-
Glioma / drug therapy*
-
Glioma / genetics
-
Glioma / metabolism
-
Glioma / pathology
-
Histones / genetics
-
Histones / metabolism
-
Humans
-
Membrane Potential, Mitochondrial / drug effects
-
Membrane Potential, Mitochondrial / genetics
-
Mitochondria / genetics
-
Mitochondria / metabolism
-
Poly (ADP-Ribose) Polymerase-1
-
Poly(ADP-ribose) Polymerases / genetics
-
Poly(ADP-ribose) Polymerases / metabolism
-
Protein Transport / drug effects
-
Protein Transport / genetics
-
RNA, Small Interfering / genetics
-
Sodium-Hydrogen Exchangers / genetics
-
Sodium-Hydrogen Exchangers / metabolism
-
Urokinase-Type Plasminogen Activator / genetics
-
Urokinase-Type Plasminogen Activator / metabolism
Substances
-
Apoptosis Inducing Factor
-
CCND1 protein, human
-
H2AX protein, human
-
Histones
-
RNA, Small Interfering
-
Sodium-Hydrogen Exchangers
-
Cyclin D1
-
Amiloride
-
PARP1 protein, human
-
Poly (ADP-Ribose) Polymerase-1
-
Poly(ADP-ribose) Polymerases
-
Urokinase-Type Plasminogen Activator
-
Caspases