The role of autophagy in the death of L1210 leukemia cells initiated by the new antitumor agents, XK469 and SH80.
The phenoxypropionic acid derivative 2-{4-[(7-chloro-2-quinoxalinyl)oxy]phenoxy}propionic acid (XK469) and an analogue termed 2-{4-[(7-bromo-2-quinalinyl)oxy]phenoxy}propionic acid (SH80) can eradicate malignant cell types resistant to many common antitumor agents. Colony formation assays indicated that a 24 h exposure of L1210 cells to XK469 or SH80 inhibited clonogenic growth with CI(90) values of 10 and 13 micromol/L, respectively. This effect was associated with G(2)-M arrest and the absence of any detectable markers of apoptosis (i.e., plasma membrane blebbing, procaspase 3 activation, loss of mitochondrial membrane potential, and formation of condensed chromatin). Drug-treated cells increased in size and eventually exhibited the characteristics of autophagy (i.e., appearance of autophagosomes and conversion of microtubule-associated protein light chain 3-I to 3-II). The absence of apoptosis was not related to an inhibition of the apoptotic program. Cultures treated with XK469 or SH80 readily underwent apoptosis upon exposure to the Bcl-2/Bcl-x(L) antagonist ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate. Continued incubation of drug-treated cells led to a reciprocal loss of large autophagic cells and the appearance of smaller cells that could not be stained with Höechst dye HO33342, had a chaotic morphology, were trypan blue-permeable, and lacked mitochondrial membrane potential. L1210 cells cotreated with the phosphatidylinositol-3-kinase inhibitor wortmannin, or having reduced Atg7 protein content, underwent G(2)-M arrest, but not autophagy, following XK469 treatment. Hence, the therapeutic actions of XK469/SH80 with L1210 cultures reflect both the initiation of a cell cycle arrest as well as the initiation of autophagy.
Kessel
David
D
Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA. dhkessel@med.wayne.edu
Reiners
John J
JJ
Hazeldine
Stuart T
ST
Polin
Lisa
L
Horwitz
Jerome P
JP
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D000071193:Autophagy-Related Protein 7; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D022162:Cytoplasmic Vesicles / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D020868:Gene Silencing; D007700:Kinetics; D007938:Leukemia / Q000473:pathology*; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000172:deficiency / Q000235:genetics; D010447:Peptide Hydrolases / Q000378:metabolism; D011422:Propionates / Q000737:chemistry / Q000494:pharmacology*; D011810:Quinoxalines / Q000737:chemistry / Q000494:pharmacology*; D014410:Tumor Stem Cell Assay; D014617:Vacuoles / Q000187:drug effects / Q000648:ultrastructure; D000077191:Wortmannin
C502473:2-(4-((7-bromo-2-quinolinyl)oxy)phenoxy)propionic Acid; D000730:Androstadienes; D000970:Antineoplastic Agents; C502661:Atg7 protein, mouse; D008869:Microtubule-Associated Proteins; D011422:Propionates; D011810:Quinoxalines; C118180:XK 469; D010447:Peptide Hydrolases; D053148:Caspase 3; C108711:DEVDase; D000071193:Autophagy-Related Protein 7; D000077191:Wortmannin