@article{11c508d65a234fc58896ffa9881d2cea,
title = "PML-RARα enhances constitutive autophagic activity through inhibiting the Akt/mTOR pathway",
abstract = "Autophagy is a highly conserved, closely regulated homeostatic cellular activity that allows for the bulk degradation of long-lived proteins and cytoplasmic organelles. Its roles in cancer initiation and progression and in determining the response of tumor cells to anticancer therapy are complicated, and only limited investigation has been conducted on the potential significance of autophagy in the pathogenesis and therapeutic response of acute myeloid leukemia. Here we demonstrate that the inducible or transfected expression of the acute promyelocytic leukemia (APL)-specific PML-RARα, but not PLZF-RARα or NPM-RARα, fusion protein upregulates constitutive autophagy activation in leukemic and nonleukemic cells, as evaluated by hallmarks for autophagy including transmission electron microscopy. The significant increase in autophagic activity is also found in the leukemic cells-infiltrated bone marrow and spleen from PML-RARα-transplanted leukemic mice. The autophagy inhibitor 3-methyladenine significantly abrogates the autophagic events upregulated by PML-RARα, while the autophagic flux assay reveals that the fusion protein induces autophagy by increasing the on-rate of autophagic sequestration. Furthermore, this modulation of autophagy by PML-RARα is possibly mediated by a decreased activation of the Akt/mTOR pathway. Finally, we also show that autophagy contributes to the anti-apoptotic function of the PML-RARα protein. Given the critical role of the PML-RARα oncoprotein in APL pathogenesis, this study suggests an important role of autophagy in the development and treatment of this disease.",
keywords = "Acute promyelocytic leukemia (APL), Apoptosis, Autophagy, PML-RARα, mTOR",
author = "Ying Huang and Hou, {Jia Kai} and Chen, {Ting Ting} and Zhao, {Xu Yun} and Yan, {Zhao Wen} and Jing Zhang and Jie Yang and Kogan, {Scott C.} and Chen, {Guo Qiang}",
note = "Funding Information: TRIzol reagent (Invitrchainreaction. Total RDo notogen, 15596018), followed by treatNA from the cells was extractdment ed by isfor heappretr caciatrrefued thil Ee hbnglish eelp fruditinom Drtg of t. Hehe man-Yi Z.anuscript.huang in our laboratory with RNase-free DNase (Promega, M610A). RT-PCR was per- formed with Promega RNA PCR kit following the manufac-FinancialSupport turer{\textquoteright}s instructions. Real-time PCR was performed and data This work is supported in part by grants from the were analyzed as described previously in reference 53. cDNA National Basic Research Program of China (973 Program) encoding LC3 and β-actin was amplified by the primers: 5'-GTA (NO2009CB918404), National Natural Science Foundation of AGA TCT ATG CCG TCG GAG AAG ACC-3' (forward) and China (NSFC, 30630034, 30870523, 90813034, 81070431), 5'-GCG AAT TCT TAC ACT GAC AAT TTC ATC CCG-3' Chinese Academy of Sciences (KSCX2-YW-R-097), Science and (reverse) for human LC3B and 5'-CAT CCT CAC CCT GAA Technology Commission of Shanghai (08JC1413400) as well GTA CCC-3' (forward) and 5'-AGC CTG GAT AGC AAC as leading academic discipline project of Shanghai Municipal GTA CAT G-3' (reverse) for β-actin. Education Commission (J50201). The contribution of S.C.K. Funding Information: ShRNA design and transfection. Three pairs of comple-was supported by NIH grant CA95274. Dr. Guo-Qiang Chen is mentary oligonucleotides specifically against beclin 1 (respec-supported by Shanghai Ling-Jun Talent Program. tively named B-sh1 to 3) were synthesized, annealed and ligated into pSIREN-RetroQ vector according to the manufacturer{\textquoteright}s instructions (Clontech, 631526). The target sequences for beclin 1 were shown as following: 5'-AAC TCA GGA GAG",
year = "2011",
month = oct,
doi = "10.4161/auto.7.10.16636",
language = "English (US)",
volume = "7",
pages = "1132--1144",
journal = "Autophagy",
issn = "1554-8627",
publisher = "Landes Bioscience",
number = "10",
}