ABSTRACT
Telomerase expression and telomere maintenance are critical for long-term cell proliferation and survival, and they play important roles in development, aging, and cancer. Cumulating evidence has indicated that regulation of the rate-limiting subunit of human telomerase reverse transcriptase gene (hTERT) is a complex process in normal cells and many cancer cells. In addition to a number of transcriptional activators and repressors, the chromatin environment and epigenetic status of the endogenous hTERT locus are also pivotal for its regulation in normal human somatic cells and in tumorigenesis.
Subject(s)
Animals , Humans , Mice , Cell Transformation, Neoplastic , Chromatin , Genetics , Metabolism , DNA Methylation , Epigenomics , Gene Expression Regulation, Enzymologic , Mice, Transgenic , Promoter Regions, Genetic , Telomerase , Genetics , Telomere , Transcription, GeneticABSTRACT
Objective: To investigate expression of TRAP in human tumors and correlativity between TRAP and hTERT and to explore the role of TRAP in tumorigenesis. Methods: TRAP was expressed in E.coli . and polyclonal antibody was prepared by immunization of New Zealand rabbits. Expressions of TRAP gene and hTERT in human tumors were analyzed by immunohistochemistry. The eukaryotic expression vectors of TRAP were constructed and transferred stably into HeLa cells to be analysed with Northern blot, TRAP PCR ELISA, growth curve, nude mouse transplantation. Results: Polyclonal antibody was obtained from New Zealand rabbits immunized with TRAP fuse protein, which was inducibly expressed in E.coli ., and its specificity was verified in Western blot. TRAP staining was detected in 213 (86.2%)of 247 malignant tumors. On the contrary, TRAP in all tissues adjacent to tumors was negative.There is a obvious difference between borderline,pre cancerous and benign lesion in the expression of TRAP.Furthermore, hTERT staining was conducted and its result was consistent with that of TRAP. Up regulation and down regulation of hTERT expression and telomerase activity were observed respectively in HeLa cells transfected stably with sense and antisence TRAP recombination. Increased proliferation presented in the former and growth inhibition in the latter. Besides, in nude mice, tumorigenecity of sense TRAP transfected HeLa cells was enhanced while tumor growth of antisense TRAP transfected HeLa cells was retarded. Conclusion: The expression of TRAP, which could be detected in most of human cancers and part of pre cancerous lesions, was correlated with expression of hTERT. The status of TRAP expression could regulate telomerase activity and present effects on growth and tumorigeneity of cancer cells. This suggests that TRAP is involved in human tumorigenesis through regulation of telermarase activity.
ABSTRACT
This paper deals with preventive effect of scopo-lamine hydrobromide in glycerin induced acute re-nal failure in rabbits. 24 hours after glycerin injection, the renal flow of controls was reduced 65%, while that of animals which received scopolamine was only reduced 33.5%. The level of angiotensin Ⅱ in the controls was increased during ARF, while that of the test group was not significantly higher than normal 24 hours after ARF. The results of FENa and RFI determination demonstrated that the drug had protective effect on the tubular Na reabsorption function.