1. Non-Cell-Autonomous Tumor Suppression by p53
Amaia Lujambio, Leila Akkari, Janelle Simon, Danielle Grace, Darjus F. Tschaharganeh, Jessica E. Bolden, Zhen Zhao, Vishal Thapar, Johanna A. Joyce, Valery Krizhanovsky, Scott W. Lowe 
Cell 
Volume 153, Issue 2, Pages (April 2013)
DOI: /j.cell
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2. Figure 1 p53 Action in HSCs Limits Fibrosis
(A) Transgenic mice were treated with CCl4 for 6 weeks, and fibrosis was assessed by Sirius red (top) and H&E (bottom) staining. Scale bars, 100 μm.
(B) Quantification of fibrosis based on Sirius red staining by laser scanning cytometry. At least three liver sections were analyzed per mouse (number of mice: n = 12, GFAP-Cre; n = 14, p53-LoxP; n = 20, HSC-p53Δ/Δ). Values are mean + SD.
(C and D) Immunoblot showing expression of αSMA in the livers of mice treated with CCl4 for 6 weeks (C). Quantification of αSMA relative to β-actin levels using ImageJ software (D). Values are mean + SD.
H&E, hematoxylin and eosin; αSMA, α-smooth muscle actin.
See also Figure S1.
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3. Figure 2 p53 Activity in HSCs Restrains Cirrhosis
(A) Abdomen width and mouse weight (week 8) and ALT and albumin levels (week 13) in mice treated with CCl4. Values are mean + SD, n = 4, GFAP-Cre; n = 5, p53-LoxP; n = 3, HSC-p53Δ/Δ.
(B) Ultrasound imaging of transgenic mice treated with CCl4 (week 8 of treatment). The live whole-mouse images show ascites only in representative HSC-p53Δ/Δ male mice.
(C) Kaplan-Meier curve documenting survival of mice treated with CCl4. Arrowhead indicates beginning of CCl4 treatment. Statistical comparison of Kaplan-Meier curves is based on the log rank test. Representative livers are displayed (white arrows represent liver retraction). Scale bars, 1 cm. GFAP-Cre in gray, n = 14; p53-LoxP in green, n = 20; HSC-p53Δ/Δ in black, n = 19.
(D) HSC-p53Δ/Δ, but not single-transgenic (GFAP-Cre and p53-LoxP), mice treated with CCl4 exhibited disrupted liver histology evaluated by H&E staining. Scale bars, 100 μm.
W8, week 8; abd, abdomen width; n, number of mice; ALT, alanine transaminase; H&E, hematoxylin and eosin.
See also Figure S2.
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4. Figure 3 p53 Activity in HSCs Limits Epithelial Tumorigenesis
(A) Schematic diagram indicating the time points for DEN and CCl4 treatment.
(B and C) Number of macroscopic tumors. Scatterplot representation: dots indicate individual animals and bars mean ± SD. If the top and bottom values are deleted in all groups: p =  (GFAP-Cre versus HSC-p53Δ/Δ) and p = (p53-LoxP versus HSC-p53Δ/Δ). If the outlier in HSC-p53Δ/Δ mice is removed: p =  (GFAP-Cre versus HSC-p53Δ/Δ) and p = (p53-LoxP versus HSC-p53Δ/Δ). Representative livers from the three genotypes are displayed. Scale bars, 1 cm. Black arrows indicate tumors.
(D) H&E (top) and reticulin (bottom) staining of a representative liver from treated HSC-p53Δ/Δ mice. Right, magnification of the boxed area on the left. Scale bars, 100 μm.
(E) Liver tissues (H&E staining, left) were stained for transgenic Lac-Z expression (β-gal staining). β-gal positive HSCs accumulated in the fibrotic scars (top). However, liver tumor cells were β-gal negative, indicating absence of recombination events. HSC-p53Δ/Δ;R26-LSL-Lacz triple-transgenic mice were used, and 36 livers were analyzed.
W, weeks; D, days; H&E, hematoxylin and eosin; T, tumor; A, adjacent liver; β-gal, β-galactosidase.
See also Figure S3.
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5. Figure 4
p53 Regulates SASP of HSCs and Genes Affecting Macrophage Function
(A) Activated HSCs from CMV-rtTA;TG-p mouse in the presence or absence of Dox (proliferating or senescent, respectively) by phase-contrast microscopy for changes in morphology (top) and expression of GFP (bottom).
(B) Activation of p53 was sufficient to restrict colony formation as assessed by crystal violet staining 10 days after plating.
(C) GSEA plot evaluating changes in p53 pathway (KEGG_p53) depending on p53 expression.
(D) GO analysis of genes significantly downregulated (red) or upregulated (blue) upon p53 expression. Differentially expressed genes were identified by comparing senescent (blue) versus proliferating (red) HSCs. Representative examples are displayed.
(E and F) Murine cytokine array for conditioned media from proliferating versus senescent HSCs. Bars represent the average of intensity of two independent experiments (log2). Factors showing 2-fold increase (blue) or decrease (red) on senescent versus proliferating HSCs are shown. In the right, representative blots from the cytokine array (F).
ES, enrichment score; NES, normalized enrichment score; S, senescent; P, proliferating.
See also Figure S4 and Table S1.
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6. Figure 5
p53 Signaling through SASP Modulates Macrophage Polarization and Function
(A and B) Quantitative RT-PCR of Msr1, Mrc1, and Il1β expression in BMDMs (A) or KCs (B) exposed to CM from proliferating (red) or senescent (blue) HSCs. Data are relative to expression of BMDMs with CM from senescent HSCs, normalized to the average expression of the housekeeping genes Hprt and Ubc. Values are mean + SD from three independent experiments.
(C and D) BMDMs (C) and KCs (D) exhibited preferential cytotoxic activity against senescent HSCs (blue) when compared to proliferating HSCs (red). Viable cell numbers are shown and are relative to the number of viable cells without macrophages. Values are mean + SD from two independent experiments performed in triplicate.
(E) Sequence of movie frames displaying the targeting of a senescent HSC (green cell; white arrow) by BMDMs (red cells; red arrows).
(F and G) Cell viability in a coculture experiment: premalignant cells were incubated with CM from proliferating (red) or senescent (blue) HSCs and were cocultured with (+) or without (−) BMDMs. Two independent experiments were performed in triplicate for two different cell lines (F and G). Viable cell numbers are shown and are relative to the number of viable cells cultured without BMDMs and with normal media; values are mean + SD.
BMDM, bone-marrow-derived macrophages; KCs, Kupffer cells; CM, conditioned media; Ren, renilla; S, senescent; P, proliferating.
See also Figure S5 and Movies S1, S2, S3, and S4.
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7. Figure 6 NF-κB Mediates p53-Dependent SASP
(A) GSEA plots evaluating p53-dependent changes in NF-κB signaling pathway.
(B) Immunostaining of proliferating (+Dox) and senescent HSCs (−Dox) with anti-p65 antibody (top) and counterstained with DAPI (bottom) to show nuclear NF-κB accumulation and SAHF formation, respectively, in senescent HSCs.
(C) Murine cytokine array for conditioned media from senescent HSCs transduced with Renilla or p65 shRNA. Bars represent the average of two independent experiments (log2). Factors upregulated in senescent HSCs (Figure 4E) are indicated in orange.
(D) Top, cytokine array blot extract showing secreted Icam1 in cells transduced with Renilla or p65 shRNA, in proliferating or senescent HSCs. Bottom, p65 and Icam1 protein levels in the same cells. β-actin serves as loading control.
(E and F) Cytotoxicity of senescent HSCs (blue) infected with shRNAs (Renilla and p65 in E; Renilla, Il6, Ifnγ, and Icam1 in F) and incubated with (+) or without (−) BMDMs. The cytotoxicity (dark blue) is relative to the basal cytotoxicity (light blue, in the absence of incubation with BMDMs, which has been normalized to 1). Values are mean + SD from triplicates.
ES; enrichment score; NES, normalized enrichment score; Ren, renilla; BMDM, bone-marrow-derived macrophages.
See also Figures S4 and S6 and Table S1.
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8. Figure 7 p53 Activity in HSCs Promotes an Antitumor Microenvironment
(A) Quantification of viable Cd45+Cd11b+Gr1− cells in CCl4-treated mice (n = 3 from each genotype). Values are mean + SD.
(B and C) Quantitative RT-PCR of FACS-sorted Cd45+Cd11b+Gr1− cells for Il1β (B) and Mrc1 (C) expression. The results are normalized to the average expression of the housekeeping genes Hprt and Ubc and are relative to the expression in HSC-p53Δ/Δ mice. Values are mean + SD of three independent livers per genotype.
(D–H) Staining for Cd11b (red) and Il1β (green) (D) and Iba1 (red) and Mrc1 (green) (E), revealing less Cd11b+ or Iba1+ macrophages, less Cd11b+Il1β+ macrophages, and more Iba1+Mrc1+ macrophages in HSC-p53Δ/Δ CCl4-treated livers than in control livers. Quantification of Cd11b+ cells (% of total DAPI+ cells) (F), Cd11b+Il1β+ cells (% of total Cd11b+ cells) (G), and Mrc1+Iba1+ cells (% of total Iba+ cells) (H). Scale bars, 100 μm. Yellow arrows indicate double-stained cells. Values are mean + SD.
See also Figure S7.
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9. Figure S1
p53 Action in HSCs Limits Fibrosis by DDC, Related to Figure 1
(A) Transgenic mice were treated with DDC (3,5-diethoxycarbonyl-1,4-dihydrocollidine) for 6 weeks and fibrosis was assessed by Sirius Red (upper panel) and H&E (lower panel) staining. The presence of red-colored precipitates hinders the quantification of the fibrotic area. Scale bars are 100 μm.
(B and C) Immunoblot showing expression of αSMA in the livers of mice treated with DDC for 6 weeks (B). Quantification of αSMA relative to β-actin levels using ImageJ software (C). Values are mean + SD.
H&E, Hematoxylin and Eosin. αSMA, α-smooth muscle actin. SD, standard deviation.
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10. Figure S2 p53 from HSCs Restricts Tumorigenesis, Related to Figure 2
(A) HSC-p53Δ/Δ mice developed extrahepatic tumors. H&E staining. Scale bars are 100 μm. Bottom panel, magnification of boxed regions.
(B) Quantification of extrahepatic tumors. Scatter plot representation; dots indicate individual animals and bars indicate mean +/− SD.
(C and D) Genotyping PCR of macroscopic or microscopic tumors extracted by laser-capture microdissection (D). Two independent PCRs were performed per sample, in order to recognize intact (1R-1F, top panel) or recombined (1F-10R, bottom panel) p53 alleles. DNA from wild-type animals was used as control for the intact p53 gene (as wild-type animals do not present LoxP sites, the product of the PCR is smaller) (bottom panel and schematic representation). The pie chart illustrates the percentage of intact versus recombined alleles among the analyzed samples (10 samples) (C).
H&E, Hematoxylin and Eosin. WT, wild-type. NT, non-template control. Rec, recombined.
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11. Figure S3
p53 Gene Is Intact in HCC after Combined Treatment with DEN and CCl4, Related to Figure 3
(A) The combined treatment of DEN and CCl4 gave rise to hepatocellular carcinomas. H&E staining of livers of treated conditional knockouts (HSC-p53Δ/Δ). Scale bars are 100 μm. Bottom panel, magnification of boxed regions.
(B) Genotyping PCR of macroscopic or microscopic tumors extracted by microdissection. Two independent PCRs are performed per sample, in order to recognize intact (top panel) or floxed p53 alleles (bottom panel). DNA from animals with intact p53 and recombined p53 are used as controls. Ten tumors were analyzed. See also Figure S2D.
H&E, Hematoxylin and Eosin. Rec, recombined. I, intact control. R, recombined control. NT, non-template control.
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12. Figure S4
p53 Regulates SASP of HSCs and Genes Affecting Macrophage Function, Related to Figures 4 and 6
(A) Schematic representation of the transgenic animal configuration that gave rise to the activated HSCs. rtTA is regulated by the CMV promoter; p53-shRNA is linked to GFP and controlled by TRE promoter.
(B) Immunoblot showing expression of p53 (short and long exposure), p16 and p21 in proliferating and senescent HSCs treated or not with Adriamycin. Senescent HSCs showed stronger expression of p53, p16 and p21. β-actin was used as loading control.
(C) SA-β-gal and αSMA staining of activated CMV-rtTA;TG-p HSCs treated with Dox (proliferating), or untreated (senescent). Senescent cells showed the characteristic blue staining and flat morphology as well as prominent expression of HSC-marker αSMA.
(D) GSEA plot evaluating changes in senescence using a previously published data set (Fridman and Tainsky, 2008).
(E) GSEA results for biological processes. NES values are represented for 4 significant examples in proliferating (red, - p53) and senescent (blue, + p53) cells.
(F) Representative blot from the cytokine arrays. Left, proliferating cells; right, senescent cells. The boxed regions indicate the differentially secreted cytokines: in blue, upregulated in senescent cells; in red, upregulated in proliferating cells.
(G and H) Human cytokine array for conditioned media from proliferating versus senescent HSCs. Bars represent the average of intensity of two independent experiments (log2). Factors showing 1.5-fold increase (blue) or decrease (red) on senescent versus proliferating HSCs are shown. H, representative blots from the cytokine array.
rtTA, reverse tetracycline-controlled transactivator. CMV, cytomegalovirus. TRE, tetracycline response element. SA-β-gal, Senescence-associated β-galactosidase. Dox, doxycycline. ES, Enrichment score. NES, Normalized enrichment score.
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13. Figure S5
p53 Signaling through SASP Modulates Macrophage Polarization and Function and NK Cell Function, Related to Figure 5
(A and B) Immunoblots showing expression of Mrc1 in BMDMs (A) or KCs (B) exposed to CM from proliferating (P) or senescent (S) HSCs. BMDMs or KCs incubated with CM from senescent HSCs showed less expression of M2-marker Mrc1. β-actin was used as loading control.
(C) BMDMs exhibited preferential cytotoxic activity against senescent p53-WT HSCs (blue) when compared to p53-KO cells (red). Two independent experiments were performed in triplicate. Viable cell numbers are shown; values are mean + SD.
(D and E) SA-β-gal staining of activated proliferating (p53-KO) and senescent (p53-WT) HSCs. Senescent cells presented the characteristic blue staining and flat morphology (D, bottom panel). Both genotypes showed expression of αSMA (D, top panel). Expression of p53 in p53-WT HSCs was sufficient to restrict colony formation as assessed by crystal violet staining 10 days after plating (E).
(F) NK cells exhibited preferential cytotoxic activity against senescent HSCs (blue). Viable cell numbers by flow cytometry are shown; values are mean + SD from triplicates. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001, using Student’s t test. ns: p > 0.05.
NK, Natural killer.
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14. Figure S6
Regulation of p53-Dependent SASP by NF-κB, Related to Figure 6
(A) DAPI staining of senescent (-Dox) and proliferating (+Dox) HSC nuclei showing the typical dots of SAHF in senescent cells.
(B) Heat-map of genes differentially expressed in proliferating (P) and senescent (S) HSCs that mediate NF-kB activation. Red, upregulated in senescent HSCs; blue, downregulated in senescent HSCs.
(C) Consensus p53 binding sites (p53BS), predicted with Patch 1.0 pattern search program. The sequences below depict the consensus motif of p53 potential targets.
(D) Retroviral construct. Schematic representation of miR30-based retroviral vector (LMN) used to knockdown Icam1, Ifnγ, Il6, Renilla and p65.
(E) Quantitative RT-PCR analysis revealed transcriptional regulation of Il6, Icam1 and Ifnγ by NF-κB. Total RNA was extracted 3 days after selection with neomycin and analyzed by quantitative RT-PCR. Hprt or β2M were used as reference.
(F) Inhibition of Il6, Icam1 and Ifnγ. Activated HSCs cells were infected with the indicated shRNAs. Total RNA was extracted 3 days after selection with neomycin and analyzed by quantitative RT-PCR. Hprt or β2M were used as reference.
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15. Figure S7
p53 Activity in HSCs Promotes an Antitumor Microenvironment, Related to Figure 7
(A) Flow-cytometry plots showing less Cd11b+ macrophages in CCl4-treated HSC-p53Δ/Δ livers when compared to single transgenic control animals. Cells were gated as viable Cd45+Cd11b+Gr1− cells.
(B and C) Staining for Cd11b (red) and Il1β (green) (B), and Iba1 (red) and Mrc1 (green) (C), revealing less Cd11b+ or Iba1+ macrophages, less Cd11b+Il1b+ macrophages and more Iba1+Mrc1+ macrophages in HSC-p53Δ/Δ CCl4-treated livers (compared to control livers).
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16. Cell  , DOI: ( /j.cell )
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