miR-145 and miR-133a function as tumour suppressors and directly regulate FSCN1 expression in bladder cancer.
BACKGROUND
We have recently identified down-regulated microRNAs including miR-145 and miR-133a in bladder cancer (BC). The aim of this study is to determine the genes targeted by miR-145, which is the most down-regulated microRNA in BC.


METHODS
We focused on fascin homologue 1 (FSCN1) from the gene expression profile in miR-145 transfectant. The luciferase assay was used to confirm the actual binding sites of FSCN1 mRNA. Cell viability was evaluated by cell growth, wound-healing, and matrigel invasion assays. BC specimens were subjected to immunohistochemistry of FSCN1 and in situ hybridisation of miR-145.


RESULTS
The miR-133a as well as miR-145 had the target sequence of FSCN1 mRNA by the database search, and both microRNAs repressed the mRNA and protein expression of FSCN1. The luciferase assay revealed that miR-145 and miR-133a were directly bound to FSCN1 mRNA. Cell viability was significantly inhibited in miR-145, miR-133a, and si-FSCN1 transfectants. In situ hybridisation revealed that miR-145 expression was markedly repressed in the tumour lesion in which FSCN1 was strongly stained. The immunohistochemical score of FSCN1 in invasive BC (n=46) was significantly higher than in non-invasive BC (n=20) (P=0.0055).


CONCLUSIONS
Tumour suppressive miR-145 and miR-133a directly control oncogenic FSCN1 in BC.
Chiyomaru
T
T
Department of Urology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, Japan.
Enokida
H
H
Tatarano
S
S
Kawahara
K
K
Uchida
Y
Y
Nishiyama
K
K
Fujimura
L
L
Kikkawa
N
N
Seki
N
N
Nakagawa
M
M
D000368:Aged; D000369:Aged, 80 and over; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics*; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D008156:Luciferases / Q000378:metabolism; D008297:Male; D035683:MicroRNAs / Q000502:physiology*; D008840:Microfilament Proteins / Q000235:genetics*; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000502:physiology*; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000473:pathology / Q000517:prevention & control
D002352:Carrier Proteins; C502658:FSCN1 protein, human; C548234:MIRN133 microRNA, human; C541010:MIRN145 microRNA, human; D035683:MicroRNAs; D008840:Microfilament Proteins; D012333:RNA, Messenger; D025521:Tumor Suppressor Proteins; D008156:Luciferases