Terminal Deoxynucleotidyl Transferase in a Case of Childhood Acute Lymphoblastic Leukemia

Abstract

Cells from a patient with childhood acute lymphoblastic leukemia contain an apparent DNA polymerase activity that was not found in any other cells except thymus cells. The enzyme has the properties of terminal transferase, an enzyme known to be found in thymocytes. The cells also contain the three major DNA polymerases found in growing cells. The results suggest that these tumor cells arose from a block in the differentiation of thymocytes. Terminal transferase may be a marker for the origin of leukemic cells. Mammalian cells contain several DNA polymerases (1-8).We have been analyzing the content of soluble DNA polymerases in various types of cells, using phosphocellulose columns to separate the activities from a crude extract, and a series of synthetic template -primer combinations to help identify the enzymes. Using this methodology, we have recently observed in cells of a child with acute lymphoblastic leukemia (ALL) a DNA polymerizing activity that was not present in many other types of cells. This paper describes the observation and the evidence that this enzyme is terminal transferase, an enzyme specific to thymocytes (9).The nomenclature of mammalian DNA polymerases is confusing, since a wide range of inconsistent sets of names is used for the enzymes. From both the literature and our own analyses, there appear to be three major DNA polymerases in most mammalian cells. As a necessary background to the presentation of our work we have developed the following nomenclature. The 6-8S DNA polymerase, found mainly in the cytoplasmic portion of cell extracts, is DNA polymerase C (1, 10, 11). The content of this enzyme in cells varies widely and is dependent on the growth rate of the cells (Chang, McKay, & Bollum, J. Mol. Biol., in press). The second enzyme, which sediments at 3.3 S, is called DNA polymerase N, and is generally recovered from the nuclear fraction of cell extracts (3,5). This enzyme is detected in appreciable amounts in all cells and does not vary with the rate of cell growth (3,5,12). A similar activity, present in the cytoplasm, is assumed to be related to the nuclear enzyme. The third enzyme, assayed by measuring poly(dT) synthesis stimulated by poly(A) . oligo(dT) in the presence of Mn++ (6, 13), is called DNA polymerase A. It is present in most cells that we have examined, and has been reported by many investigators (13-15). It has been considered to be a "reverse transcriptase in uninfected cells," but there seems to be no utility in this designation. MATERIALS AND METHODS

Terminal Deoxyribonucleotidyl Transferase in Human Leukemia

“…One could imagine that malignant transformation had occurred in a pluripotential stem or early progenitor cell with production of multiple types of more differentiated cells in both the myeloid and lymphoid lines. Although transferase is normally present in high concentration only in thymus, its presence in hematopoietic cells of patient MR and children with acute lymphoblastic leukemia (4,5) suggests that lymphoid progenitor cells from bone marrow as well as thymocytes may contain transferase. The major reservoir of lymphoid progenitor cells in adults is thought to be bone marrow (17), an I such cells are probably rare.…”

“…The unique localization of the transferase is of uncertain biological significance, but there are speculations that it may play a role in conveying immunological specificity (or immunological diversity) to T and possibly B lymphocytes during their differentiation (1,3,4). Demonstration of deoxyribonucleotidyl transferase activity in leukemic cells of certain children with acute lymphoblastic leukemia (5) and cell lines derived from patients with acute lymphoblastic leukemia (6) leads to the suggestion that malignant cells in acute lymphoblastic leukemia might arise from thymocytes or their precursors (5).…”

Terminal deoxynucleotidyl transferase activities and glucocorticoid receptors in leukaemia

“…Since the discovery of high TdT activity in blasts of an ALL case (McCaffrey et al, 1973) there have been many studies on this enzyme in leukaemia. Thus far, in most cases of ALL (Coleman et al, 1976;Greenwood et al, 1977), in about one third of cases with CML in blast crisis (Sarin et al, 1976;Sasaki & Sakamoto, 1977) and in a few cases with acute myelogenous leukaemia (AML) (Stass et al, 1979), high enzyme activities were reported.…”

Terminal deoxynucleotidyl transferase activity in lymphoma

“…The enzyme is present in 1-5% of murine marrow cells (Pazmino et al, 1977) and is restricted to the immature cortisone-sensitive fraction of thymic lymphocytes. The enzyme has also been found in the cells of patients with non-T, non-B, acute lymphoblastic leukaemia (ALL), T-cell ALL, and of some patients with blast transformation of chronic granulocytic leukaemia (CGL), but is usually absent in other types of leukaemia (McCaffrey et al, 1973;1975;Coleman et al, 1974Coleman et al, , 1976Sarin et al, 1976;Hoffbrand et al, 1977). It appears therefore that the enzyme is present in the pluripotential marrow stem cell and is lost as cells mature down the myeloid or lymphoid pathways, being retained only in thymocytes.…”