[Effects of antisense human telomerase reverse-transcript protein subunit (hTERT) gene on biological characteristics of hepatoblastoma cell line in vitro].
OBJECTIVE
Telomerase, a complex of ribose and nucleoprotein, is a specific marker of tumor, which expresses in 98% infinite cell lines and 90% malignant tumor organizations and whose function is to maintain the length of telomere. Human telomerase reverse-transcript protein subunit (hTERT) is the key element and rate-limiting factor of telomerase activity. Our study was to investigate the effects of antisense hTERT gene on biological characteristics of hepatoblastoma cell line in vitro.


METHODS
The sense and antisense hTERT eukaryotic expression vectors that we had constructed before were transfected into hepatoblastoma cell line HepG2 by using the SuperFect transfection reagent (Qiagen) according to the manufacturer's instructions, then the HepG2-s and HepG2-as of G418-resistant colonies were obtained with G418 and identified for the presence of hTERT insert by PCR with T7 and pcDNA3.1/BGH reverse primers. After that, we have detected the endogenous hTERT mRNA expression and telomerase activity by quantitative real-time RT-PCR and TRAP-silver staining assay in cells from each group. Meanwhile, MTT cellular proliferation assay, soft agar colony formation assay and flow cytometry were employed to analyze if the proliferation capacity of liver cancer cells was affected in vitro and the tumor cells could be induced to apoptosis by antisense hTERT.


RESULTS
Antisense hTERT significantly down-regulated the endogenous hTERT mRNA expression (15.35 +/- 1.72/HepG2-as, 43.8 +/- 2.89/HepG2-s, 45.2 +/- 3.46/HepG2) (n = 10, t = 7.61, P < 0.01) and telomerase activity in HepG2, compared to blank control and sense hTERT. After 20 passages of three group cells, a 7-day cell growth curve and the numbers (size) of soft agar colony formation showed the proliferation and the anchorage-independent growth in HepG2-as were significantly suppressed (50.6 +/- 4.8/HepG2-as, 113.52 +/- 8.15/HepG2-s, 119.12 +/- 10.82/HepG2) (n = 10, t = 4.54, P < 0.01 and n = 10, t = 3.96, P < 0.01), compared to HepG2 and HepG2-s. However there was a significant increase in apoptosis percentage of HepG2-as by flow cytometry (n = 10, t = 9.24, P < 0.01 and n = 10, t = 8.37, P < 0.01), compared to control group.


CONCLUSIONS
Antisense hTERT could significantly suppress the hepatoblastoma cell growth and reverse its malignant phenotypes in vitro and cause the increase in apoptosis percentage of HepG2, thus it might be applied in malignant tumor gene therapy through the telomerase-targeted molecular mechanism.
Department of Surgery, Shenzhen Children's Hospital, Shenzhen, 518026 China. liulei3322@yahoo.com.cn
Lei
L
Liu
Chen-rong
CR
Li
Lai-bao
LB
Sun
Guo-bing
GB
Wang
Bing
B
Wang
D002455:Cell Division / Q000235:genetics; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins; D018197:Hepatoblastoma / Q000235:genetics / Q000473:pathology; D006801:Humans; D016372:RNA, Antisense / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019098:Telomerase / Q000235:genetics*
D004268:DNA-Binding Proteins; D016372:RNA, Antisense; D012333:RNA, Messenger; D019098:Telomerase