title: Inhibiting PLK1 induces autophagy of acute myeloid leukemia cells via mammalian target of rapamycin pathway dephosphorylation.
abstract: Decreased autophagy is accompanied by the development of a myeloproliferative state or acute myeloid leukemia (AML). AML cells are often sensitive to autophagy‑inducing stimuli, prompting the idea that targeting autophagy can be useful in AML cytotoxic therapy. AML NB4 cells overexpressing microtubule-associated protein 1 light chain 3-green fluorescent protein were screened with 69 inhibitors to analyze autophagy activity. AML cells were treated with the polo-like kinase 1 (PLK1) inhibitors RO3280 and BI2536 before autophagy analysis. Cleaved LC3 (LC3-II) and the phosphorylation of mammalian target of rapamycin (mTOR), adenosine monophosphate-activated protein kinase, and Unc-51-like kinase 1 during autophagy was detected with western blotting. Autophagosomes were detected using transmission electron microscopy. Several inhibitors had promising autophagy inducer effects: BI2536, MLN0905, SK1-I, SBE13 HCL and RO3280. Moreover, these inhibitors all targeted PLK1. Autophagy activity was increased in the NB4 cells treated with RO3280 and BI2536. Inhibition of PLK1 expression in NB4, K562 and HL-60 leukemia cells with RNA interference increased LC3-II and autophagy activity. The phosphorylation of mTOR was reduced significantly in NB4 cells treated with RO3280 and BI2536, and was also reduced significantly when PLK1 expression was downregulated in the NB4, K562 and HL-60 cells. We demonstrate that PLK1 inhibition induces AML cell autophagy and that it results in mTOR dephosphorylation. These results may provide new insights into the molecular mechanism of PLK1 in regulating autophagy.
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Yan-Fang
authors.initials: YF
authors.lastname: Tao
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Zhi-Heng
authors.initials: ZH
authors.lastname: Li
authors.affiliation: Department of Hematology and Oncology, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Du
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Li-Xiao
authors.initials: LX
authors.lastname: Xu
authors.affiliation: Department of Hematology and Oncology, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Jun-Li
authors.initials: JL
authors.lastname: Ren
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Xiao-Lu
authors.initials: XL
authors.lastname: Li
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Mei
authors.initials: M
authors.lastname: Li
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Guang-Hui
authors.initials: GH
authors.lastname: Qian
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Li
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Li
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Xing
authors.initials: X
authors.lastname: Feng
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: CAM-SU Genomic Resource Center, Soochow University, Suzhou, Jiangsu 215123, P.R. China.
authors.forename: Wei-Qi
authors.initials: WQ
authors.lastname: He
authors.affiliation: Department of Hematology and Oncology, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Shao-Yan
authors.initials: SY
authors.lastname: Hu
authors.affiliation: Department of Hematology and Oncology, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.affiliation: Institute of Pediatrics, Children's Hospital of Soochow University, Suzhou, Jiangsu 215003, P.R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Pan
mesh_terms: D000818:Animals; D001343:Autophagy; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation; D002648:Child; D005260:Female; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008297:Male; D051379:Mice; D009367:Neoplasm Staging; D010766:Phosphorylation; D011379:Prognosis; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D015996:Survival Rate; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays; D000097869:Polo-Like Kinase 1
chemical_list: D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D058570:TOR Serine-Threonine Kinases; D000097869:Polo-Like Kinase 1; C546842:MTOR protein, human