title: Polo-like kinase 1 regulates cell proliferation and is targeted by miR-593* in esophageal cancer.
abstract: Polo-like kinase 1 (PLK1) is overexpressed in various human cancers. However, the biological functions and the post-transcriptional regulations of PLK1 in esophageal cancer (EC) are still unknown. The purposes of our study are to determine whether PLK1 can be a molecular target of EC therapy and to identify a microRNA (miRNA) targeting PLK1. We performed loss-of-function and gain-of-function experiments regarding cell proliferation, cell cycle, apoptosis, in vivo tumor formation and luciferase reporter assays, using siRNAs against PLK1 and miRNA. PLK1 protein was expressed in all 11 EC cell lines, but not in normal esophageal epithelial cells (HEEpiC). Knockdown of PLK1 in EC cells induced G2/M arrest (p < 0.001) in cell cycle assay and reduced cell proliferation (p = 0.019) and tumor formation ability in vivo (p < 0.0001). MiR-593*, identified as a miRNA targeting PLK1 by a database search, was less expressed especially in six EC cell lines than HEEpiC cells. Moreover, miR-593* expression level was inversely correlated with PLK1 mRNA level in 48 clinical tissue specimens of EC (p = 0.006). Introduction of synthetic miR-593* suppressed PLK1 expression by 69-73%, reduced cell proliferation (p = 0.008) and increased cell proportion of G2/M phase (p = 0.01) in HSA/c (an EC cells), whereas a miR-593* inhibitor upregulated PLK1 expression by 11-55%. Additionally, luciferase assay demonstrated that miR-593* interacted two binding sites in the PLK1 3'-UTR and reduced 56.8-71.5% of luciferase activity by degrading luciferase mRNA in HSA/c cells. In conclusion, PLK1 is post-transcriptionally regulated by miR-593* and could be a promising molecular target for EC treatment.
authors.affiliation: Division of Gastroenterology, Department of Medicine and Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Ito
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Sato
authors.forename: Takatsugu
authors.initials: T
authors.lastname: Kan
authors.forename: Yulan
authors.initials: Y
authors.lastname: Cheng
authors.forename: Stefan
authors.initials: S
authors.lastname: David
authors.forename: Rachana
authors.initials: R
authors.lastname: Agarwal
authors.forename: Bogdan C
authors.initials: BC
authors.lastname: Paun
authors.forename: Zhe
authors.initials: Z
authors.lastname: Jin
authors.forename: Alexandru V
authors.initials: AV
authors.lastname: Olaru
authors.forename: James P
authors.initials: JP
authors.lastname: Hamilton
authors.forename: Florin M
authors.initials: FM
authors.lastname: Selaru
authors.forename: Jian
authors.initials: J
authors.lastname: Yang
authors.forename: Nobutoshi
authors.initials: N
authors.lastname: Matsumura
authors.forename: Kazuharu
authors.initials: K
authors.lastname: Shimizu
authors.forename: John M
authors.initials: JM
authors.lastname: Abraham
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Shimada
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Mori
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Meltzer
mesh_terms: D020413:3' Untranslated Regions; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004938:Esophageal Neoplasms / Q000201:enzymology* / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D035683:MicroRNAs / Q000378:metabolism*; D008875:Middle Aged; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism*; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism; D000097869:Polo-Like Kinase 1
chemical_list: D020413:3' Untranslated Regions; D018797:Cell Cycle Proteins; D035683:MicroRNAs; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D000097869:Polo-Like Kinase 1; C577650:MIRN593 microRNA, human