Poly(adenosine diphosphoribose) polymerase in peripheral blood leukocytes from normal donors and patients with malignancies.

A two-color flow cytometric technique was developed to analyze poly(ADP-ribose) polymerase (PADPRP) in different individuals as a function of different physiological or pathological conditions and to establish the basis for determining whether enzyme deficiency may predispose to degenerative or malignant disorders. Peripheral blood granulocytes were devoid of enzyme activity, whereas mononuclear cells had variable amounts. PADPRP was highest in B cells, intermediate in T cells, and lowest in monocytes. This pattern of enzyme distribution and relative enzyme content of different types of cells was remarkably constant in normal subjects. In a series of 66 normal donors there was no significant biological variation in enzyme content as a function of age, race, or sex. The mean PADPRP values in peripheral blood mononuclear cells from 81 random patient samples obtained from an ambulatory oncology clinic did not differ significantly from normal subjects. However, groups of patients with breast cancer, lymphocytic malignancies, and esophageal cancer were observed to have below normal levels for peripheral blood mononuclear cell PADPRP.

Drastic reduction of topoisomerase II alpha associated with major acquired resistance to topoisomerase II active agents but minor perturbations of cell growth.

V511 and V513 cell lines, derived from Chinese hamster V79 cells following alkylating agent mutagenesis and subsequent selection with VP-16, showed resistance to cytotoxicity and DNA strand breaks induced by topoisomerase (topo) II inhibitors and were resistant to VP-16-induced sister chromatid exchanges. They showed no amplification of the multidrug-resistant p-glycoprotein. In a kinetoplast-DNA decatenation assay, V511 and V513 showed 51% and 49% topo II activity relative to parental V79 cells, respectively. By western-blot analysis all three logarithmically growing cell lines showed similar levels of topo II beta (M(r) 180,000), which increased as cells progressed to quiescence. In contrast, immunoreactive levels of topo II alpha (M(r) 170,000) were 6.8% in V511 and 62.4% in V513 relative to V79. V511 showed drastically decreased topo II alpha in both log growth and quiescence. In a second approach, immunoreactive topo II was analyzed in different phases of the cell cycle in logarithmically growing cells fractionated by fluorescence-activated cell sorting. All cell lines demonstrated relatively stable topo II beta throughout the cell cycle. Topo II alpha showed little cell cycle variation in V79 or V513. However, in V511, it was only detectable at low levels in G2/M phase. When cell growth parameters were measured, V511 and V513 showed a 17% increase in cell doubling time relative to V79. These studies indicate that cells with a drastic reduction in topo II alpha (V511) or mutant topo II alpha (V513) but with normal levels of topo II beta show only minor perturbations of cell growth.