Complex expression pattern of the CEF-4 cytokine in transformed and mitogenically stimulated cells

Abstract

The transformation of chicken embryo fibroblasts (CEF) by the Rous sarcoma virus leads to the constitutive expression of the cellular gene designated CEF-4. With specific antisera, we confirmed that transformed cells actively synthesize and secrete a 6 kDa polypeptide corresponding to the CEF-4 gene product. The expression of CEF-4 was investigated by Northern and immunoprecipitation analyses. Upon activation of pp60v-src in cells infected by a ts mutant of RSV, the expression of CEF-4 was biphasic with an early transient and a late constitutive period of expression. CEF-4 was expressed in cells transformed by a variety of oncogenes, but the level of constitutive expression differed quantitatively among transformed cells. Cells transformed by v-myc alone did not express CEF-4. Unlike other members of the interleukin 8 gene family, CEF-4 was induced in response to a broad spectrum of growth factors and inflammatory agents. Dexamethasone repressed the induction of CEF-4 by lipopolysaccharides but had little or no effect on the response to serum or pp60v-src. These data emphasize the complexity of CEF-4 expression and suggest the existence of multiple levels or pathways of CEF-4 regulation in normal and transformed cells.