Induction of autophagy during extracellular matrix detachment promotes cell survival.
Autophagy has been proposed to promote cell death during lumen formation in three-dimensional mammary epithelial acini because numerous autophagic vacuoles are observed in the dying central cells during morphogenesis. Because these central cells die due to extracellular matrix (ECM) deprivation (anoikis), we have directly interrogated how matrix detachment regulates autophagy. Detachment induces autophagy in both nontumorigenic epithelial lines and in primary epithelial cells. RNA interference-mediated depletion of autophagy regulators (ATGs) inhibits detachment-induced autophagy, enhances apoptosis, and reduces clonogenic recovery after anoikis. Remarkably, matrix-detached cells still exhibit autophagy when apoptosis is blocked by Bcl-2 overexpression, and ATG depletion reduces the clonogenic survival of Bcl-2-expressing cells after detachment. Finally, stable reduction of ATG5 or ATG7 in MCF-10A acini enhances luminal apoptosis during morphogenesis and fails to elicit long-term luminal filling, even when combined with apoptotic inhibition mediated by Bcl-2 overexpression. Thus, autophagy promotes epithelial cell survival during anoikis, including detached cells harboring antiapoptotic lesions.
Fung
Christopher
C
Department of Pathology, University of California San Francisco, San Francisco, CA 94143, USA.
Lock
Rebecca
R
Gao
Sizhen
S
Salas
Eduardo
E
Debnath
Jayanta
J
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects; D000071187:Autophagy-Related Protein 5; D000071193:Autophagy-Related Protein 7; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004285:Dogs; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology* / Q000187:drug effects; D066246:ErbB Receptors / Q000378:metabolism; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D006801:Humans; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000172:deficiency / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D044764:Ubiquitin-Activating Enzymes / Q000172:deficiency / Q000378:metabolism
C502778:ATG5 protein, human; D000071187:Autophagy-Related Protein 5; D008869:Microtubule-Associated Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; C509349:ATG7 protein, human; D000071193:Autophagy-Related Protein 7; D044764:Ubiquitin-Activating Enzymes