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Journal of Environmental Pathology, Toxicology and Oncology
Impact-faktor: 1.241 5-jähriger Impact-Faktor: 1.349 SJR: 0.356 SNIP: 0.613 CiteScore™: 1.61

ISSN Druckformat: 0731-8898
ISSN Online: 2162-6537

Journal of Environmental Pathology, Toxicology and Oncology

DOI: 10.1615/JEnvironPatholToxicolOncol.2018027885
pages 13-20

Autophagy is Required to Regulate Mitochondria Renewal, Cell Attachment, and All-trans–Retinoic Acid–Induced Differentiation in NB4 Acute Promyelocytic Leukemia Cells

Ibrahim Tekedereli
Department of Experimental Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, TX
Ugur Akar
Department of Breast Medical Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX
S. Neslihan Alpay
Department of Cancer Biology, The University of Texas M.D. Anderson Cancer Center, Houston, TX
Gabriel Lopez-Berestein
Department of Experimental Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, TX
Bulent Ozpolat
Department of Experimental Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, TX

ABSTRAKT

All-trans–retinoic acid (ATRA) is a potent inducer of cellular differentiation, growth arrest, and apoptosis as well as a front-line therapy for acute promyelocytic leukemia (APL). The present study provides evidence that induction of autophagy is required for ATRA to induce differentiation of APL (NB4) cells into granulocytes. ATRA treatment causes ~12-fold increase in the number of acidic vesicular organelles and induces marked up-regulation of LC3-II, autophagy-related 5 (ATG5), and Beclin-1. Transmission electron microscopy (TEM) revealed a decrease in mitochondria and ATRA-induced differentiation. To determine the role of autophagy in the differentiation of APL, we knocked down ATG5 in NB4 cells to find that ATRA-induced differentiation is significantly inhibited during ATG5 knock down in cells, indicating the role of autophagy in differentiation of APL. Further experiments revealed restriction of autophagy during ATRA-induced differentiation and inhibition of tissue transglutaminase 2 (TG2) and phospho–focal adhesion kinase (p-FAK), which are known to have roles in differentiation and cell attachment. We examined expression of Beclin-1 and B-cell lymphoma–2 (Bcl-2) and levels of mechanistic target of rapamycin (mTOR) after ATRA treatment. ATRA inhibits Bcl-2, up-regulates Beclin-1 expression, and reduces induction of mTOR activation/phosphorylation in NB4 cells. Our results reveal that autophagy has roles in regulation of differentiation, mitochondria elimination, and cell attachment during ATRA-induced APL differentiation.