Inhibitions Of Telomerase Activity On K562 Cell Line By Plasmid-vector Directing RNAi Against HTERT

Backgroud and Objective: Telomere, the specific DNA-protein complex on the end of eukaryotic chromosomes, can maintain the stableness and completion of chromosomes. It becomes shorter gradually when cells divided until the loss, fusion, recombination, and degradation of chromosomes and cells apoptosis, so it is named the"biological clock"of cell division. Telmerase, a kind of reverse transcriptase, can use its own RNA template to synthesize the repeated sequences (5-TTAGGG-3)n of telomere DNA, and adds them to the chromosomes ends, maintains telomere length, results in cellular immortalization or oncogenesis. Telomerase was composed of six subunits: human telomerase RNA (hTR), telomerase associated protein (TP-1), human telomerase-reverse transcriptase (hTERT), heat shock protein (hsp90), molecular companion (p23) and dyskerin. Researches indicate that hTERT is an important subunit of telomerase complex, which is expressed in 80-90% cancer tissue and has close correlation with telomerase activity, is a rate limiting factor of telomerase activity, so it is an ideal target of telomerase activity inhibition and tumor therapy. RNAi, which was first found in nemathelmnth by Fire in 1998, is a kind of post-transcription gene silencing mechanism that is triggered by homologous double-strand RNA, and then causes the degradation of targeting mRNAs. Later studies indicate that it is a highly defensive guard mechanism generally existing in lower plants and high mammal. RNAi is a new gene-silencing technique by strengthening RNAi mechanism against aimed gene to control abnormal protein synthesizing in disease and outside pathogenesis nucleic acid copy and expression. In recent researches RNAi technique with its high...