Loss of STAT1 expression confers resistance to IFN-γ-induced apoptosis in ME180 cells

Abstract Interferon gamma (IFN-γ) induces apoptosis in many tumor cell lines and sensitizes tumor cells to apoptosis by tumor necrosis factor family members. IFN-γ induces the expression of many early response genes such as interferon regulatory factor-1 (IRF-1) by activation of signal transducer and activator of transcription (STAT) factor proteins. We found that ME180 cells became resistant to IFN-γ-induced cell death after 4–5 passages in culture. These resistant cells were characterized by a loss of STAT1 expression and a loss of inducible IRF-1 expression. We describe for the first time the emergence of a STAT1-deficient ME180 cell line.