1. IL6 secretion is a hallmark of postsenescence.
IL6 secretion is a hallmark of postsenescence. A, combined loss of the Pten and Trp53 genes causes primary MEFs to proliferate more aggressively when compared with the single genotypes. Error bars, SD; n ≥ 3; *, P < 0.05 with ANOVA, Dunnett post hoc test on all genotypes versus WT at days 4 and 6. B, IL6 is secreted specifically after simultaneous loss of Pten and Trp53 genes. A threshold of 3-fold was used to filter upregulated proteins specific for Trp53Δ/Δ, PtenΔ/Δ, and PtenΔ/Δ;Trp53Δ/Δ cells. CCL5 (RANTES), CXCL1 (KC), and CXCL10 (IP-10) proteins were upregulated in both Trp53Δ/Δ and PtenΔ/Δ;Trp53Δ/Δ cells. C, protein secretion represented as log2-transformed fold expression relative to WT and normalized to total cellular protein content. Note that there are no proteins specifically secreted in PtenΔ/Δ MEFs that exceed the 3-fold cutoff. n = 3. Note that we cannot exclude stimulation of protein secretion in senescence (i.e., in the Pten-null cells) below the threshold criteria. D, ELISA results confirm increased expression of IL6 in conditioned medium from PtenΔ/Δ;Trp53Δ/Δ MEFs. ANOVA, Dunnett post hoc test, **, P < 0.01, versus WT; error bars, SD; n = 3. E, increased transcription of IL6 is observed in PtenΔ/Δ;Trp53Δ/Δ MEFs compared with WT. ANOVA, Dunnett post hoc test, **, P < 0.01, versus WT; error bars, SD; n = 4.
Dawid G. Nowak et al. Cancer Discovery 2015;5:
©2015 by American Association for Cancer Research