Vitamin D analog EB1089 triggers dramatic lysosomal changes and Beclin 1-mediated autophagic cell death.
A chemotherapeutic vitamin D analogue, EB1089, kills tumor cells via a caspase-independent pathway that results in chromatin condensation and DNA fragmentation. Employing transmission- and immunoelectronmicroscopy as well as detection of autophagosome-associated LC3-beta protein in the vacuolar structures, we show here that EB1089 also induces massive autophagy in MCF-7 cells. Interestingly, inhibition of autophagy effectively hindered apoptosis-like nuclear changes and cell death in response to EB1089. Furthermore, restoration of normal levels of beclin 1, an autophagy-inducing tumor suppressor gene that is monoallelically deleted in MCF-7 cells, greatly enhanced the EB1089-induced nuclear changes and cell death. Thus, EB1089 triggers nuclear apoptosis via a pathway involving Beclin 1-dependent autophagy. Surprisingly, tumor cells depleted for Beclin 1 failed to proliferate suggesting that even though the monoallelic depletion of beclin 1 in human cancer cells suppresses EB1089-induced autophagic death, one intact beclin 1 allele is essential for tumor cell proliferation.
Høyer-Hansen
M
M
Apoptosis Department, Institute of Cancer Biology, Danish Cancer Society, Copenhagen, Denmark.
Bastholm
L
L
Mathiasen
I S
IS
Elling
F
F
Jäättelä
M
M
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D051017:Apoptosis Regulatory Proteins; D001343:Autophagy / Q000187:drug effects; D000071186:Beclin-1; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002103:Cadaverine / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D002117:Calcitriol / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology; D002403:Cathepsins / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D048708:Cell Growth Processes / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D020285:Cryoelectron Microscopy; D004347:Drug Interactions; D016147:Genes, Tumor Suppressor; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D008565:Membrane Proteins; D011506:Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D034741:RNA, Small Interfering / Q000235:genetics; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; D008565:Membrane Proteins; D011506:Proteins; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; C025946:3-methyladenine; D002403:Cathepsins; D002117:Calcitriol; C008542:monodansylcadaverine; D000225:Adenine; D002103:Cadaverine; C078903:seocalcitol