Alteration of growth and differentiation factors response by Kirsten and Harvey sarcoma viruses in the IL-3-dependent murine hematopoietic cell line 32D C13(G)

Abstract

32D C13(G) is an interleukin 3(IL3)-dependent non-tumorigenic murine hematopoietic cell line which undergoes terminal differentiation into granulocytes when exposed to granulocytic colony stimulating factor (G-CSF). Infections of 32D C13(G) cells with either Kirsten rat sarcoma virus or Balb murine sarcoma virus, both containing a v-ras oncogene, generates clones that can permanently grow in G-CSF without differentiation. 32D-Ki-ras cells show a heterogeneous morphology ranging from the promyelocytic to the myelocytic stage of differentiation, and express high levels of both myeloperoxidase (MPO) and lactoferrin (LF) mRNA. 32D-Ha-ras cells show a more immature phenotype and express MPO but no LF mRNA. The apparent differentiation block of both 32D Ki-ras and 32D Ha ras can be reversed by treatment with the chemical inducers retinoic acid, sodium butyrate or dimethylsulphoxide, which leads to terminal differentiation into granulocytes. When 32D-Ki-ras and 32D-Ha-ras cells are cultured in medium containing IL-3 they become adherent and express some monocyte-macrophage markers. Upon prolonged exposure to IL3, 32D-Ki-ras, but not 32D-Ha-ras, resume suspension growth. Both 32D-Ki-ras and 32D-Ha-ras rapidly die if grown in chemically defined medium in the absence of any growth factor and are non-tumorigenic in immunosuppressed mice. These findings indicate that ras activation may interfere with the normal response to growth and differentiation factors in cells of the granulocytic lineage. These alterations may represent a critical, although non-sufficient, step in leukemogenesis.