Showing papers on "Friend leukemia published in 2016"

Inducibility of spleen focus-forming virus by BrdUrd is controlled by the differentiated state of the cell (Friend cells/Friend anemia virus/Friend polycythemia virus/thymidine kinase/erythroid differentiation)

Abstract: All Friend cells-except thymidine kinase (ATP:thymidine 5'-phosphotransferase, EC 2.7.1.21)-deficient mutants-are highly inducible for the release of biologically active spleen focus-forming virus (SFFV) after exposure to BrdUrd. We studied SFFV production in somatic cell hybrids made between Friend leukemia cells (FLC) and cells expressing various differ- entiation programs. High inducibility of SFFV and release of.con- stitutive Friend virus (FV) and SFFV are eliminated in all hybrids in which the potential for erythroid differentiation is suppressed. FV release and its induction by BrdUrd are unchanged in hybrids that maintain the expression of erythroid differentiation. Friend virus (FV)-transformed Friend leukemia cells (FLC) grow in culture and differentiate to cells that synthesize hemo- globin on exposure to dimethyl sulfoxide (Me2SO) (1, 2). Some but not all of these cell lines, release type C virus (3, 4). How- ever, all FLC lines except those that do not incorporate BrdUrd (3), whether derived through transformation with the polycy- themia-producing strain of FV (FVP) (3) or the anemia-produc- ing strain of FV (FVA) (this paper), are highly inducible for spleen focus-forming virus (SFFV) release. The inducibility is several orders of magnitude above that observed for endoge- nous virus induction in normal murine fibroblastic cell lines (5). The property of superinduction could be related to a general property such as the transformed state of a cell or could be as- sociated specifically with a particular type of differentiated cell. To distinguish between these alternatives, we tested cell hy- brids between FLC and cells of hematopoietic and nonhema- topoietic origin (6-9).