Tumor-specific enzymes, presence

Other important monitoring parameter for thyroid carcinoma is the presence of tumor cells in bone marrow or the circulation of tumor cells in peripheral blood. For the detection of these tumor cells, molecular methods based on the detection of tissue-specific gene expression are developed. The most efficient molecular marker is mRNA encoding to the thyroid-specific hormone thyroglobulin (Tg), a further target is mRNA encoding specific enzymes involved in the synthesis of thyroid hormones such as thyroid peroxidase (TPO). Thyroid transcription factor-1 (TTF-1) is another thyroid-specific marker, which can be used for the diagnosis of thyroid tumors. 

Other enzymes are also useful indices of liver pathology. Serum alkaline phosphatase is often a useful indicator of liver and bone disease. The alkaline phosphatases are a diverse group of enzymes that catalyze reactions in which a phosphate is removed from a phosphate ester, especially at an alkaline pH. Physicians don t care about this. They do care that serum alkaline phosphatase levels often rise with bone breakdown (as in tumor infiltration) and in liver disease, especially where tliere is obstruction of the bile duct. Acid phosphatase is particularly rich in the prostate. A rise in its serum levels provides a test as to the presence of prostate carcinoma. This test has largely been replaced by assay for Prostate Specific Antigen (PSA), a serine protease that is elevated in prostatic carcinoma. 

Yes, the incorporation of nucleoside triphosphates into an acid-insoluble form is indicative of the presence of a polymerase. The polymerase is likely a DNA polymerase because dNTPs, and not NTPs, were used to form product. Further evidence for a DNA polymerase was that the radiolabeled product was destroyed by a nuclease, DNase, specific for hydrolyzing DNA, and not by one specific for RNA hydrolysis. Additionally, NaOH, which destroys RNA but not DNA, did not destroy the radiolabeled product. Pretreatment of the extract with the two hydrolytic enzymes demonstrated that the enzyme depends on an RNA and not a DNA template for its activity. Thus, this enzyme is an RNA-dependent DNA polymerase. No such enzyme had been observed previously in a cell, and this demonstration, along with similar findings by Howard Temin, of its existence in an RNA tumor virus caused a revision of Francis Crick s central dogma of molecular biology, which stated that information flowed from DNA to RNA to proteins. The demonstration of this RNA-dependent DNA polymerase suggested that in some cases information could flow from RNA to DNA. (This question was derived from D. Baltimore. Viral RNA-dependent DNA polymerase. Nature 226 [1971]1209-1213.)... 

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