Silencing Id-1 with RNA interference inhibits adenoid cystic carcinoma in mice.
BACKGROUND
The helix-loop-helix (HLH) protein Id-1 (inhibitor of DNA binding/differentiation) has been demonstrated to play an important role in tumor development. Our previous in vitro research has shown that Id-1 is a potential target in the treatment of human adenoid cystic carcinoma (ACCM). The purpose of this study was to analyze the influence of Id inhibition on ACCM in mice.


METHODS
To suppress the expression of Id-1 gene, we used lentivirus-mediated RNA interference to silence the Id-1 gene post-transcriptionally in ACCM models that stably express GFP in mice. Tumor development was evaluated by size measurement. Effects of Id-1 siRNA on mRNA and protein expression of Id-1 were analyzed using quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting respectively. Ki-67 expression was measured by immunohistochemistry. In vitro studies of Hoechst staining for cell apoptosis, Boyden-chamber assay for cell invasion, and MTT-tests for cell growth were performed as well.


RESULTS
Id-1 knockdown resulted in inhibition of tumor growth in mice. Id-1 siRNA significantly decreased not only Id-1 in mRNA and protein level, but also Ki-67 expression. In addition, apoptosis was induced and cell proliferation activity and invasion were significantly reduced.


CONCLUSIONS
Lentivirus-mediated gene knockdown by silencing Id-1 constitute a valid methodological approach, which may represent an attractive, potent and specific therapeutic tool for the treatment of ACCM.
Chen
Zhenggang
Z
School of Stomatology, Shandong University, Jinan, People's Republic of China.
Liu
Shaohua
S
Sumida
Tomoki
T
Sun
Shanzhen
S
Wei
Yuan
Y
Liu
Meng
M
Dong
Zuoqing
Z
Zhang
Fan
F
Hamakawa
Hiroyuki
H
Wei
Fengcai
F
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D003528:Carcinoma, Adenoid Cystic / Q000473:pathology* / Q000503:physiopathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004195:Disease Models, Animal; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology; D020868:Gene Silencing / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D051798:Inhibitor of Differentiation Protein 1 / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000502:physiology; D016086:Lentivirus / Q000235:genetics; D008297:Male; D051379:Mice; D008819:Mice, Nude; D034622:RNA Interference / Q000502:physiology*; D023041:Xenograft Model Antitumor Assays / Q000379:methods
C497455:Idb1 protein, mouse; D051798:Inhibitor of Differentiation Protein 1; D049452:Green Fluorescent Proteins