FIGURE 4.

CXCL1 is expressed in senescent cells and upregulates GH. (a–e) Western blots of CXCL1 expression after senescence induction. (a) Oncogene‐induced senescence. hNCC were infected with lentivirus expressing constitutively activated HRAS oncogene (lentiV‐12HRAS) or empty vector (lenti‐CMV) and analyzed 7 days later. (b) DNA damage‐induced senescence. hNCC were exposed to indicated doses of UVC light or left untreated (C) and analyzed 6 days later. (c) Replicative senescence. hNCC were passaged until proliferation was significantly reduced. Cells from Passage 8 (p.8) and Passage 61 (p.61) were compared. In a–c, loading control is the same as in Figure 1a–c. (d) Western blot of senescent organoids cultured for up to 4 months. (e) Western blot of CXCL1 and its receptor CXCR2 in hNCC 72 h after treatment with 3 μM nutlin3 (Nutlin), 5 μM etoposide (Etop), or DMSO as control (C) for 48 h. ImageJ quantification of western blots is depicted in Figure S6A–F. (f–h) Western blots of (f) organoids treated with 100 ng/mL CXCL1 for 4 days; (g) hNCC treated with indicated doses of CXCL1 for 4 days; and (h) hNCC in replicative senescence (p.61) infected with lenti‐shCXCL1 or lenti‐shScr and analyzed 3 days after infection. ImageJ quantification of western blots is depicted in Figure S7A–D. Representative blots from at least three independent experiments are shown.