Extended Data Fig. 5. Interferon gamma (IFNγ) strongly induces PD-L1 expression in senescent but not proliferating human breast cancer cells and ex vivo plated mouse mammary tumor cells.

A) Mammary tumor cells from a 3642 transplant were isolated and plated at 5% O2, and the next day untreated (Unt) or made senescent over 7 days by treatment with doxorubicin (Doxo, 0.75µM for 24 hr) as indicated. These cultures were then exposed to rIFNγ (10ng/ml) for 24h (IFNγ) or not (Control). RNA was extracted and qPCR for indicated genes was performed. Representative images of the treated, plated cells are shown before harvest. Shown are individual data points representative of biologically independent cell harvests (n=3 for each group), with mean and SEM. B) MCF-7 cells were similarly plated and either untreated or made senescent by doxorubicin treatment (250nM for 24 hr). These cultures were then exposed to rIFNγ (10ng/ml) for 24h (IFNγ) or not (Control). RNA was extracted and qPCR for indicated genes was performed. Shown are individual data points representative of biologically independent cell harvests (n=3 for each group), with mean and SEM. Statistical significance was determined using one-way ANOVA with Tukey’s posttest for comparisons of three or more groups. qPCR was repeated at least twice and representative data are shown