miR-320b suppresses cell proliferation by targeting c-Myc in human colorectal cancer cells.
BACKGROUND
MicroRNAs (miRNAs) are small noncoding RNAs that potentially play a critical role in tumorigenesis. Mounting evidence indicates that one specific miRNA: miR-320b is down regulated in numerous human cancers, including colorectal cancer (CRC); making the hypothesis that miR-320b may play a key role in tumorigenesis plausible. However, its role in carcinogenesis remains poorly defined. The goal of this study is to better clarify the role of miR-320b in tumor growth of CRC.


METHODS
Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was conducted to detect the expression of miR-320b in CRC tissues and 5 CRC cell lines. The effect of miR-320b on cell proliferation was analyzed in vitro and in vivo. Furthermore, a luciferase reporter assay was performed to measure the target effects of miR-320b. Lastly, the messenger RNA (mRNA) and protein levels of the gene c-MYC were measured in CRC cell lines and tissues by qRT-PCR, and confirmed via Western blot and Immunohistochemical (IHC) staining.


RESULTS
The results presented here showed that miR-320b expression was down regulated in both CRC tissues and cells. Overexpression of miR-320b in CRC cells was statistically correlated with a decrease of cell growth in vitro and in vivo, while c-MYC was identified as a target gene of miR-320b in CRC. Furthermore, it was found that up-regulation of c-Myc can attenuate the effects induced by miR-320b.


CONCLUSIONS
Our identification of c-MYC as a target gene of miR-320b provides new insights into the pathophysiology of CRC proliferation, and identifies miR-320b as a novel therapeutic target for the treatment of CRC.
Department of Colorectal Surgery, Changhai Hospital, Shanghai, 200433, China. hantaowang@126.com.
Hantao
H
Wang
Department of Colorectal Surgery, Changhai Hospital, Shanghai, 200433, China. caofuao@gmail.com.
Fuao
F
Cao
Department of Colorectal Surgery, Changhai Hospital, Shanghai, 200433, China. xuli_ch@163.com.
Xu
X
Li
Department of General Surgery, The First People's Hospital of Pinghu, Pinghu, 314200, Zhejiang Province, China. 13567330917@139.com.
Hua
H
Miao
Department of Colorectal Surgery, Changhai Hospital, Shanghai, 200433, China. jefershon@163.com.
Jifu
J
E
Department of Colorectal Surgery, Changhai Hospital, Shanghai, 200433, China. xjj2118@163.com.
Junjie
J
Xing
Department of Colorectal Surgery, Changhai Hospital, Shanghai, 200433, China. fugang416@126.com.
Chuan-Gang
CG
Fu
D000328:Adult; D000368:Aged; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D004195:Disease Models, Animal; D015536:Down-Regulation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D016259:Genes, myc; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000737:chemistry / Q000235:genetics*; D008875:Middle Aged; D034622:RNA Interference; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D047368:Tumor Burden; D023041:Xenograft Model Antitumor Assays
C554214:MIRN424 microrna, human; D035683:MicroRNAs; D012333:RNA, Messenger