Document 0078
 DOCN  M9440078
 TI    Friend virus-transformed cells express hemoglobin and become responsive
       to erythropoietin upon expression of p53 protein (Meeting abstract).
 DT    9404
 AU    Johnson P; Chung S; Benchimol S; Dept. of Medical Biophysics, Ontario
       Cancer Inst., Univ. of; Toronto, Toronto, Ontario, Canada
 SO    6th p53 Workshop. November 1-5, 1992, Tiberias, Israel, p. 38, 1992..
       Unique Identifier : AIDSLINE ICDB/94698122
 AB    The murine allele ts p53val135 encodes a temperature-sensitive p53
       protein that behaves as a mutant polypeptide at 37 C and as a wild type
       polypeptide at 32 C. We have stably introduced this ts allele into the
       p53 nonproducer, Friend erythroleukemia cell line DP16-1. This cell line
       was derived from a mouse infected with the polycythemia strain of Friend
       virus and like other erythroleukemia cell lines transformed by this
       virus, grows independently of erythropoietin due to expression of the
       viral env gp55 protein which binds to and activates the erythropoietin
       receptor. When incubated at 32 C, DP16-1 cells expressing ts p53val135
       protein arrested in the G1/G0-phase of cell cycle, rapidly lost
       viability and expressed hemoglobin, a marker of erythroid
       differentiation. Erythropoietin had a striking effect on
       p53val135-expressing cells at 32 C by prolonging their survival and
       diminishing the extent of hemoglobin production. This response to
       erythropoietin was not accompanied by downregulation of viral gp55
       protein. In the clonogenic assays that have been developed to examine
       hemopoietic precursors, erythropoietin is a necessary component for the
       development of erythroid colonies. Erythroid colonies result from cells
       undergoing proliferation and differentiation, and so it has been
       difficult to assign a specific role to erythropoietin in this process.
       Our data indicate that erythropoietin prolongs the survival of Friend
       cells expressing wild-type p53 protein and argues against a role for
       erythropoietin in initiating the differentiation process in Friend
       cells.
 DE    Animal  Cell Cycle  Cell Transformation, Neoplastic  Cell
       Transformation, Viral  Down-Regulation (Physiology)
       Erythropoietin/*METABOLISM  Friend Virus/*PATHOGENICITY  Gene Products,
       env/METABOLISM  Hemoglobins/*METABOLISM  Leukemia, Erythroblastic,
       Acute/*METABOLISM  Mice  Protein p53/GENETICS/*METABOLISM  Tumor Cells,
       Cultured  MEETING ABSTRACT

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).