Effect of the VP3 gene of chicken anemia virus on canine mammary tumor cells.
OBJECTIVE
To investigate the antitumor effect of the chicken anemia virus (CAV) VP3 gene in canine mammary tumor (CMT) cells. SAMPLE POPULATIONS: Established primary canine cell lines that originated from epithelial cells of resected CMTs and nonneoplastic mammary gland epithelial (MGE) cells.


METHODS
Expression vectors and lentiviral vectors encoding the VP3 gene from a Taiwan-Ilan isolate of CAV were used to deliver the VP3 gene into CMT cells and nonneoplastic MGE cells. Ectopic gene expression and the pro-apoptotic effect of the VP3 gene on CMT and nonneoplastic MGE cells by either transfection or viral infection were evaluated via immunofluorescence microscopy, western blot analysis, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling analysis.


RESULTS
Overexpression of the enhanced green fluorescent protein-VP3 fusion protein was detected predominantly in the nuclei of CMT cells. In contrast, the VP3 protein was localized to the cytoplasm of nonneoplastic MGE cells. Among the fusion protein-expressing CMT cells, most underwent characteristic changes of apoptosis, whereas apoptosis was not detected in fusion protein-expressing, nonneoplastic MGE cells. Induction of apoptosis by VP3 gene overexpression in CMT cells was associated with the caspase-9-, but not the caspase-8-, mediated apoptosis pathway.


CONCLUSIONS
These data indicate that the VP3 gene of the CAV induces apoptosis in malignant CMT cells, but not in nonneoplastic canine MGE cells. On the basis of such tumor cell-specific killing, the VP3 gene may be a promising agent for the treatment of malignant mammary gland tumors in dogs.
Lee
Jih-Jong
JJ
Department and Graduate Institute of Veterinary Medicine, College of Bio-Resources and Agriculture, National Taiwan University, No. 1, Section 4, Roosevelt Rd, Taipei 106, Taiwan.
Chen
Poshen B
PB
Yang
Su-Hua
SH
Cheng
Chiung-Hsiang
CH
Chueh
Ling-Ling
LL
Pang
Victor F
VF
Hsiao
Michael
M
Lin
Chung-Tien
CT
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western / Q000662:veterinary; D036022:Capsid Proteins / Q000494:pharmacology / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D017727:Chicken anemia virus / Q000235:genetics*; D004283:Dog Diseases / Q000628:therapy*; D004285:Dogs; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D020287:In Situ Nick-End Labeling / Q000662:veterinary; D016086:Lentivirus; D015674:Mammary Neoplasms, Animal / Q000628:therapy*; D008856:Microscopy, Fluorescence / Q000662:veterinary
D036022:Capsid Proteins; C091717:VP3 protein, Chicken anemia virus