[Effects of RNA interference on epidermal growth factor receptor expression in breast cancer cells: a study in tumor-bearing nude mice].
OBJECTIVE
To investigate the effect of cationic liposome-mediated RNA interference (RNAi) in silencing epidermal growth factor (EGF) receptor (EGFR) gene in breast cancer cells in vivo.


METHODS
A small interfering RNA (siRNA) targeting EGFR gene was constructed and transfected into human breast cancer cell in vitro via cationic liposome. The transfected cells were inoculated into nude mice, and the tumor growth inhibition rate was calculated. The tumors were then removed for immunohistochemistry and Western blotting to examine the expression of EGFR protein. Quantitative RT-PCR was used to detect the mRNA expression of the EGF receptor gene, and enzyme-linked immunosorbent assay (ELISA) performed to assess the EGF level in both the serum and tumor extraction.


RESULTS
In athymic nude mice, MDA-MB-231 cells had obviously lower tumor formation rate than ZR-75 cells (30.00% and 88.89%). Transfection of the cells with EGFR siRNA significantly inhibited tumor formation capacity of the cells in vivo as compared with the cells transfected with empty vector or irrelevant siRNA. The results of ELISA demonstrated that in mice bearing the tumors grown from EGFR siRNA-transfected cells, the EGF levels in the serum and tumor extraction were lowered by 16.77% and 12.59%, respectively. Real-time RT-PCR showed that EGFR siRNA transfection caused a specific downregulation of EGFR mRNA expression by 21.05% in the tumor.


CONCLUSIONS
Chemically synthesized 21-nucleotide siRNA duplexes can be effectively delivered via lipofectamine 2000 into breast cancer cells in vivo to induce a longer-lasting gene silencing effect than in vitro transfection. RNAi of EGFR gene may indicate a promising approach for management of lung cancers, especially those nodular ones with easy access.
Wu
Wei-Dong
WD
Department of Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
Fang
Chi-Hua
CH
Yang
Zheng-Xin
ZX
D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D045744:Cell Line, Tumor; D004797:Enzyme-Linked Immunosorbent Assay; D066246:ErbB Receptors / Q000096:biosynthesis / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D008325:Mammary Neoplasms, Experimental / Q000235:genetics / Q000473:pathology / Q000628:therapy; D051379:Mice; D008819:Mice, Nude; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics*; D011897:Random Allocation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
D034741:RNA, Small Interfering; D066246:ErbB Receptors