Xu Jin-Heng, Wang Yu-Chuan, Geng Xin, Zhang Wei-Ming
Department of Biochemistry and Molecular, Tianjin Medical University,Tianjin, 300070, P. R. China.
Ai Zheng. 2008 Dec;27(12):1271-6.
BACKGROUND & OBJECTIVE: The expression of human telomerase reverse transcriptase (hTERT) is positively correlated to the activity of telomerase. Alternative splicing exists in the transcription of hTERT and special splicing patterns may change during tumor progression. This study was to reveal the changes of hTERT alterative splicing pattern in gastric carcinogenesis.
Three alternative splicing sites (alpha, beta, gamma) were selected to design primers. The expression of eight hTERT alternative splicing variants (ASVs) in 18 specimens of normal gastric mucosa, 20 specimens of precancerous lesions and 19 specimens of gastric cancer was detected by semi-nested reverse transcription-polymerase chain reaction (RT-PCR). The expression of beta site-remaining ASV (beta+ hTERT mRNA) in precancerous lesions and gastric cancer tissues was detected by SYBR Green real-time RT-PCR.
The positive rate of alpha+beta+gamma+ hTERT mRNA was significantly higher in gastric cancer than in precancerous lesions and normal mucosa (94.7% vs. 40.0% and 0, P<0.05). The positive rates of other ASVs were not different among the three groups. The positive rates of beta-deletion ASV were 72.2% in normal mucosa, 95.0% in precancerous lesions and 100.0% in gastric cancer. The positive rates of beta+ hTERT mRNA (including alpha+beta+gamma+ hTERT mRNA, alpha-deletion ASV, gamma-deletion ASV, alphagamma-deletion ASV) were 11.1% in normal mucosa, 40.0% in precancerous lesions and 94.7% in gastric cancer (P<0.05). The mRNA level of beta+ hTERT was 6.99 times higher in gastric cancer than in precancerous lesions.
hTERT alternative splicing pattern changes during gastric carcinogenesis. beta+ hTERT mRNA is expressed increasingly during gastric carcinogenesis and may provide useful information for diagnosis of gastric cancer or precancerous lesions.
人端粒酶逆转录酶（hTERT）的表达与端粒酶活性呈正相关。hTERT转录过程中存在可变剪接，且特殊剪接模式可能在肿瘤进展过程中发生变化。本研究旨在揭示hTERT可变剪接模式在胃癌发生过程中的变化。
选择三个可变剪接位点（α、β、γ）设计引物。采用半巢式逆转录-聚合酶链反应（RT-PCR）检测18例正常胃黏膜标本、20例癌前病变标本和19例胃癌标本中8种hTERT可变剪接变体（ASVs）的表达。采用SYBR Green实时RT-PCR检测癌前病变和胃癌组织中β位点保留的ASV（β+ hTERT mRNA）的表达。
α+β+γ+ hTERT mRNA的阳性率在胃癌中显著高于癌前病变和正常黏膜（94.7%对40.0%和0，P<0.05）。其他ASVs的阳性率在三组之间无差异。β缺失ASV的阳性率在正常黏膜中为72.2%，在癌前病变中为95.0%，在胃癌中为100.0%。β+ hTERT mRNA（包括α+β+γ+ hTERT mRNA、α缺失ASV、γ缺失ASV、αγ缺失ASV）的阳性率在正常黏膜中为11.1%，在癌前病变中为40.0%，在胃癌中为94.7%（P<0.05）。胃癌中β+ hTERT的mRNA水平比癌前病变高6.99倍。
hTERT可变剪接模式在胃癌发生过程中发生变化。β+ hTERT mRNA在胃癌发生过程中表达逐渐增加，可能为胃癌或癌前病变的诊断提供有用信息。
