Telomerase activity

Telomeres are a special structure at the end of a chromosome in eukaryotes and consist of a repeating DNA sequence rich in guanine and its associated proteins. Telomeres are essential for the stability of chromosome ends. Maintenance of telomere length requires the presence of telomerase activity. Endogenous cytokines play an important role in the long-term survival of immortalized cells and tumor cells. Telomerase is a complex of RNA and protein. It is a specific RNA-dependent reverse transcriptase. It can synthesize telomeric DNA at the end of chromosome from its own RNA to make up for telomere during cell division. Loss of DNA, maintain the length of telomeres, maintain the dynamic balance of chromosomes, and make cells immortalized. Since the establishment of highly sensitive PCR-based methods for detecting telomerase, telomerase has attracted widespread attention. It has been found that telomerase has a close relationship with cell proliferation, differentiation and immortality, and has become one of the hotspots of basic research on tumor and aging. Basic Information Specialist classification: Oncology examination classification: immune examination Applicable gender: whether men and women apply fasting: not fasting Analysis results: Below normal: Normal value: no Above normal: negative: The normal value is negative. Positive: (1) Liver cancer patients have a higher telomerase positive rate (85%). (2) Telomerase is highly expressed in most malignant tumor tissues, such as neuroblastoma (94%), breast cancer (93%), colorectal cancer (93%), gastric cancer (85%), prostate cancer. (84%), lung cancer (80%), etc. Telomerase activity is closely related to the clinical stage and prognosis of the tumor. (3) There may be weak telomerase activity in a few benign lesions (such as hepatitis, cirrhosis, benign meningioma, etc.). Tips: There may be weak telomerase activity in a few benign lesions (such as hepatitis, cirrhosis, benign meningioma, etc.). Normal value negative. Clinical significance 1, liver cancer patients have a higher telomerase positive rate (85%), telomerase activity positive AFP levels are significantly higher than telomerase activity negative. Telomerase activity was not significantly associated with tumor size, histological grade, and tumor metastasis. Telomerase may be a tumor marker for the diagnosis of liver cancer. 2. Telomerase is highly expressed in most malignant tumor tissues, such as neuroblastoma (94%), breast cancer (93%), colorectal cancer (93%), gastric cancer (85%), and prostate cancer ( 84%), lung cancer (80%), etc. Telomerase activity is closely related to the clinical stage and prognosis of the tumor. Therefore, telomerase is currently the most specific and universal tumor marker. 3. There may be weak telomerase activity in a few benign lesions (such as hepatitis, cirrhosis, benign meningioma, etc.). Positive results may be diseases: neuroblastoma, colorectal cancer, breast cancer, stomach cancer, liver cancer, prostate cancer, colon cancer, renal cell carcinoma, thyroid cancer In recent years, the "telomere, telomerase hypothesis" has been confirmed by more and more research, using telomerase activity level as a biomarker and prognostic indicator for tumor diagnosis. 1. Pay attention to prevent laboratory contamination and false positive or false negative. 2. Pay attention to remove the polymerase inhibitor contained in the tissue specimen to reduce false negatives. 3. Scintillation analysis technology, ELISA method, in situ hybridization method are more reliable than TRAP method. Inspection process Check operation: Genomic DNA was 0.1 μg; buffer containing 50 mmol/L potassium chloride, 10 mmol/LTris-HCl (pH 8.4), 1.5 mmol/L magnesium chloride, 100 μg gelatin; each primer was 0.25 μmol/L; dATP, dCTP, dGTP The dTIP was 200 μmol/L each; the DNA polymerase was 2.5 U, and the final volume was 100 μl. Add a few drops of liquid paraffin to prevent evaporation. Reaction cycle: 1 denaturation: 90 ° C 30 ~ 60 s; 2 primer and template annealing temperature: 40 ~ 60 ° C 30 ~ 60s; 3 extension: 72 ° C 1-2 min. After repeated cycles of 30 to 40 times, the last 7° 72°C primer extension was terminated for 7 minutes. After removal of the liquid paraffin, the product is available for analysis. After electrophoresis on agarose gel, it was stained with ethidium bromide, and a fluorescent strip of expected amplification length was observed by irradiation with a UV lamp. The product can also be hybridized to a Southern blot or a spot blot with a radiolabeled or non-radiolabeled oligonucleotide probe. It is more convenient to use the PCR automatic instrument. After adding the reaction reagent, DNA template and Taq-DNA polymerase to the test tube, it is put into the adjusted procedure, that is, the required temperature, time, and extension of the respective temperature and time and the number of cycles. The reaction is carried out in an automatic instrument to obtain a satisfactory amplification product. Not suitable for the crowd Those who do not have a suitable test should not be tested. Adverse reactions and risks 1. Infection: Pay attention to aseptic operation when collecting blood, avoid contamination of water and other parts at the blood collection site to avoid local infection. 2, bleeding: after the blood is given a full compression time, especially coagulopathy, bleeding tendency, to avoid local subcutaneous oozing, bruising and swelling.

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