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. Author manuscript; available in PMC: 2016 Jul 22.
Published in final edited form as: Cell Death Discov. 2016 Jul 4;2:16045. doi: 10.1038/cddiscovery.2016.45

Figure 5.

Figure 5

LPO signaling and DNA damage synergize to induce AS. (a and b) Double immunofluorescence staining for LPO marker 4-HNE and DNA damage marker γH2AX (phospho-Ser139). (a) B16-F10 cells treated with DMSO only exhibited low levels of 4-HNE and negligible levels of γH2AX at 96 h, whereas (b) cells treated with etoposide exhibited high levels of 4-HNE and γH2AX foci at the same time point. Results indicate that DNA damage and LPO occur and persist in senescent cells induced by etoposide treatment. (c) Chemical structures of 4-HNE and 4-HNEGSH. (d–g) 4-HNE and 4-HNE-GSH were applied to cells to observe senescence induction with and without IR. (d) 4-HNE induced senescence only in a minor fraction of cells (15%) and yielded a near-background SI of 1.7, whereas (e) IR potentiated the effects of 4-HNE, resulting in 40% senescent cells and an SI of 6.1. (f and g) 4-HNE-GSH did not induce senescence on its own or with IR, indicating that 4-HNE reactivity is directly responsible for the effects seen in (d and e).