Expression of interferon-β is associated with growth arrest of murine and human epidermal cells

Abstract

The cytokine interferon-β is a regulator of cell replication and function, including invasion and induction of angiogenesis. The goal of this study was to determine whether the expression of interferon-β by cells in the epidermis correlated with terminal differentiation. In situ hybridization analysis and immunohistochemical staining of formalin-fixed, paraffin- embedded specimens of normal human and murine epidermis and human and murine skin tumors of epithelial origin revealed that only differentiated, nondividing cells of the epidermis expressed interferon-β protein. Keratinocyte cultures established from the epidermis of 3 d old mice were maintained under conditions permitting continuous cell division or induction of differentiation. Continuously dividing cells did not produce interferon- β whereas nondividing differentiated cells expressing keratin 1 did. Growth- arrested, undifferentiated keratinocytes also expressed interferon-β protein. Neutralizing interferon-β in the culture medium inhibited differentiation, but the addition of exogenous interferon-β did not stimulate differentiation. These data indicate that interferon-β is produced by growth-arrested, terminally differentiated keratinocytes.