Long-term stable expression of antisense cDNA of cyclin B1 profoundly inhibits the proliferation of tumor cells and suppresses tumorigenicity in implanted mice.
BACKGROUND
Cyclin B1 (CLB1) is necessary for mitotic initiation in mammalian cells and plays important roles in cancer development. Therefore, a potential strategy in cancer therapy is to suppress the activity of CLB1 by delivering antisense constructs of CLB1 into tumor cells. In previous CLB1 studies, antisense constructs with a short half life were often used and these constructs might not persistently inhibit CLB1.


METHODS
We successfully created a recombinant plasmid encoding the full-length antisense cDNA of mouse cyclin B1 (AS-mCLB1) and transfected this construct to the murine Lewis lung carcinoma (LL/2) and CT-26 colon carcinoma (CT-26) cells. We isolated clones of LL/2 and CT-26 transfectants with stable expression of AS-mCLB1. Reverse transcriptional polymerase chain reaction (RT-PCR) and Western blot were applied to detect the expression of the mRNA and protein levels of CLB1. To further test the efficacy of this strategy in vivo, AS-mCLB1-expressing LL/2 and CT-26 transfectants were implanted into mice.


RESULTS
We found the expression of the mRNA and protein levels of CLB1 decrease in these transfectants. The inhibition of CLB1 caused prominent G1 arrest, abnormal morphology, retarded cell growth and an increase in apoptosis. In AS-mCLB1-expressing LL/2 and CT-26 transfectants implanted mice, tumorigenicity was effectively suppressed compared with the controls. In addition, the expression of AS-mCLB1 also significantly increases the survival duration of implanted animals.


CONCLUSIONS
AS-mCLB1 is likely to be useful in future cancer therapy, which may be associated with its ability to down-regulate the expression of CLB1 and then induce G1arrest and apoptosis in tumor cells.
Zhang
Tao
T
Department of Oncology, General Hospital of Chengdu Military Command of PLA, Chengdu, Sichuan, China.
Zhang
Ling
L
Li
Ji-Cheng
JC
Wei
Dong
D
Wei
Yu-Quan
YQ
Zhang
Ru
R
Cheng
Peng
P
Chen
Xian-Cheng
XC
Liu
Huan-Yi
HY
Su
Xiao-Mei
XM
D000818:Animals; D017209:Apoptosis; D049109:Cell Proliferation; D002470:Cell Survival; D019926:Cyclin B / Q000037:antagonists & inhibitors* / Q000235:genetics; D056744:Cyclin B1; D016373:DNA, Antisense / Q000494:pharmacology*; D018076:DNA, Complementary / Q000494:pharmacology*; D016193:G1 Phase; D051379:Mice; D008810:Mice, Inbred C57BL; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000473:pathology / Q000628:therapy*
C534700:Ccnb1 protein, mouse; D019926:Cyclin B; D056744:Cyclin B1; D016373:DNA, Antisense; D018076:DNA, Complementary