| Telomeres are specialized structures at the ends of eukaryotic chromosomes that appear to function in protecting the chromosomes from DNA degradation, end-to-end fusions, rearrangements, and chromosome loss. Shorting of telomeric DNA is closely related to the cellular senescence and decease. Telomerase is a ribonucleoprotein polymerase composed of human telomerase RNA component(hTR), human telomerase reverse transcriptase(hTERT), and telomerase-associated protein 1 /telomerase protein component 1(TP1/TLP1) that synthesizes telomeric DNA onto chromosomal ends using a segment of its RNA component as a template. Numerous studies have showed the over expression of temolerase in malignant tumors and is closely related to the expression of hTR and hTERT, but not in normal somatic cells and benign lesions. The function of telomerase for maintaining the stable of telomericlenth gives a new target to deal with cancer by using an antisense oligodeoxynucleotide(ASODN) to inhibit the activity of telomerase and then proceed to induce apoptosis of tumor cells, along with going deep into the research of telomere and telomerase, The studies of the role and its mechanism for targeted therapy by using ASODN to telomerase RNA have become one of the most popular subjects of tumor pathology in recent years.Esophageal squamous cell carcinoma(ESCC) is one of leading cancers in china. Cellular progression to malignancy is thought to involve multistep events. Activation of telomerase and the stable of telomere length are required for cellular immortalization and genetic alteratens. A few of reports have documented the quantitative and qualitative detections of telomerase activity in ESCCs and in atypical hyperplasia tissues of the esophagus and the relationship between telomerase and clinicopathological features; Studies on the relationship between telomerase activity and the expression of hTR, hTERT are seldom seen; There was only one report observed telomere length in ESCCs and the relationship between telomere length and clinicopathological features, but not in atypical hyperplasia tissues of the esophagus; So far, there has been no report about the treatment and its mechanism of the telomerase activity inhibited and apoptosis induced by ASODN in vitro and in vivo. In order to investigate the expressions of telomerase activity, hTR and hTERT, the relationship between telomerase and telomere length, the effects and mechanism of cationic liposome-mediated ASODN on esophageal cancer cells, the methods of quantitative TRAP-ELISA, qualitative TRAP-silver staining, immunohistochemistry, in situ hybridization, Southern blot andchemiluminescence were used to observe the expressions of telomerase activity, hTR, hTERT and telomere length; the methods of targeted therapy in vitro and in vivo with liposome-mediated ASODN were also used to value the inhibitory effects on the growth of esophageal cancer cells and telomerase activity by blocking different sites of hTR with ASODN. Based on the condition that the functional region of hTR were obturated by ASODN-t3 for consecutive seven days, the inhibitory action of ASODN-t3 on the growth of esophageal cancer cells, telomerase activity, and the effect on induced tumor cells apoptosis were observed. All these studies would offer a theoretic foundation to elucidate the significance of telomerase in the progression of ESCCs and the targeted therapeutic pontentiality of ASODN . The studies were divided into three parts listed below:First part: Telomerase, telomere length, and their correlation in ESCCs and in atypical hyperplasia tissues of the esophagusMethods1. The positive rate of telomerase and its A value in 38 cases of ESCCs, 15 atypical hyperplasia tissues of the esophagus, and 12 normal esophageal squamous epithelial tissues were determined by using quantitative TRAP-ELISA and qualitative TRAP methods.2. Expression of hTR mRNA and hTERT protein in esophageal biopsy specimens mentioned above were observed by using immunohistochemistry,...
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