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. 2006 Dec 12;103(50):19069-74.
doi: 10.1073/pnas.0607948103. Epub 2006 Dec 5.

Crosstalk between peroxisome proliferator-activated receptor delta and VEGF stimulates cancer progression

Dingzhi Wang  1 , Haibin Wang, Yong Guo, Wei Ning, Sharada Katkuri, Walter Wahli, Beatrice Desvergne, Sudhansu K Dey, Raymond N DuBois
Affiliations

Crosstalk between peroxisome proliferator-activated receptor delta and VEGF stimulates cancer progression

Dingzhi Wang et al. Proc Natl Acad Sci U S A. .

Abstract

Peroxisome proliferator-activated receptor (PPAR) delta is a member of the nuclear hormone receptor superfamily. PPARdelta may ameliorate metabolic diseases such as obesity and diabetes. However, PPARdelta's role in colorectal carcinogenesis remains controversial. Here, we present genetic and pharmacologic evidence demonstrating that deletion of PPARdelta decreases intestinal adenoma growth in Apc(Min/+) mice and inhibits tumor-promoting effects of a PPARdelta agonist GW501516. More importantly, we found that activation of PPARdelta up-regulated VEGF in colon carcinoma cells. VEGF directly promotes colon tumor epithelial cell survival through activation of PI3K-Akt signaling. These results not only highlight concerns about the use of PPARdelta agonists for treatment of metabolic disorders in patients who are at high risk for colorectal cancer, but also support the rationale for developing PPARdelta antagonists for prevention and/or treatment of cancer.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
The effect of PPARδ deletion on intestinal polyp number and size. (A–D) Both male (A and B) and female (C and D) mice with different genotypes at the age of 13 weeks were killed to quantitate polyp number and size in the small intestine (A and C) and large intestine (B and D). Data are expressed as mean ± SE (∗, P < 0.05; Bonferroni test). (E) Representative H&E-stained sections from male PPARδ−/−/ApcMin/+ and PPARδ+/+/ApMin/+ mice are shown (Scale bar, 500 μm.)
Fig. 2.
Fig. 2.
PPARδ mediates the effect of the GW501516 in promoting intestinal polyp growth. Both PPARδ−/−/ApcMin/+ and PPARδ+/+/ApcMin/+ male (A and B) and female (C and D) mice at the age of 6 weeks were treated with vehicle or GW501516 for 7 weeks as described in Methods. At the end of the experimental period, the polyp numbers and sizes in small (A and C) and large (B and D) intestine were quantitated as described in Fig. 1.
Fig. 3.
Fig. 3.
Activation of PPARδ up-regulates VEGF expression in CRC cell lines. (A and B) After serum-free starvation for 24 h, the LS-174T cells were treated with 1 μM GW501516 for the indicated times (A) or indicated concentration (B) of GW501516 for 24 h. Quantitative real-time PCR assays were performed as described in Methods. The relative expression of target gene represents an average of triplicates normalized against the transcript levels of hβ-Actin. Data are represented as the mean ± SE of the relative expression from three independent experiments. (C) The LS-174T cells were transiently transfected with VEGF luciferase reporter and pRL-SV40 plasmids, followed by treatment with GW501516 for 24 h. The dual-luciferase assays were performed as described in Methods. Data are presented as the mean ± SE of relative luciferase activity from three independent experiments. (D) LS-174T cells were treated with GW501516 as described in Methods. The levels of VEGF in cell supernatants were determined by ELISA. Three independent experiments with duplicates were performed. (E) The polyclonal dNPPARδ or empty vector LS-174T cells were treated with 1 μM GW501516 for 24 h after serum-free starving for 24 h, and quantitative real-time PCR assays were carried out as noted in Fig. 3 A and B. (F) The wild-type or PPARδ−/− HCT116 cells were treated as described in E, and quantitative real-time PCR assays were carried out. (G) Quantitative real-time PCR analysis of the mRNA level of VEGF in indicated CRC cell lines treated with 1 μM GW501516 for 24 h after serum-free starving for 24 h. (H) A representative section shows VEGF immunoreactive staining (brown) in the intestinal polyp taken from male mice treated with vehicle and GW501516 for 7 weeks. (Scale bar, 200 μm.) VEGF expression was determined by Western blot analysis (Right). Each sample included 60 polyps collected from three animals for each experimental group.
Fig. 4.
Fig. 4.
VEGF promotes CRC cell survival and induces Akt activation. (A) Quantitative real-time PCR analysis of VEGFR mRNA were performed as described in Fig. 3 A and B. (B) LS-174T cells were treated as described in Fig. 3D. VEGFR1–2 protein levels were analyzed by Western blotting. (C) LS-174T cells were treated with VEGF as described in Methods. The number of apoptotic cells was determined by flow cytometry using an annexin V-FITC kit. Data are expressed as the mean + SE of percent of apoptotic cells from three separate experiments. (D) LS-174T cells were treated with the indicated concentration of VEGF for 2 h (Left) or 10 ng/ml VEGF for the indicated times (Right) after serum starvation for 24 h. The level of phosphorylated Akt was detected by Western blotting using anti-phospho-Akt (Ser-473) antibody. The blots were reprobed with Akt antibody to monitor the loading of samples. (E) LS-174T cells were pretreated with the inhibitor for 1 h after serum starvation for 24 h and then incubated with 1 ng/ml VEGF for 2 h. Akt activation was measured by following the same approach as mentioned above. B, D, and E are representative of three different experiments that showed similar results. (F) LS-174T cells were pretreated with the inhibitor for 1 h and then treated with VEGF for 2 days in serum-free media. The percent of apoptotic cells was measured as noted above.
Fig. 5.
Fig. 5.
VEGF mediates the effects of PPARδ on Akt activation and inhibition of apoptosis. (A) LS-174T cells were treated with the indicated concentration of GW501516 for 24 h after serum starvation for 24 h. Akt activation was measured as noted above. (B) LS-174T cells were pretreated with the inhibitor for 1 h after serum starvation for 24 h and then incubated with 1 μM GW501516 for 24 h. (C) LS-174T cells were pretreated with 1 μg/ml anti-hVEGF neutralizing antibody for 1 h and then treated with GW501516 for 24 h after serum starvation for 24 h. The above figures are representative of three different experiments with similar results. (D) LS-174T cells were pretreated with 1 μg/ml anti-hVEGF neutralizing antibody for 1 h and then treated with GW501516 for 4 days under serum-free conditions. The percentage of apoptotic cells was measured as noted above.
Fig. 6.
Fig. 6.
GW501516 activates Akt in ApcMin/+ mouse polyps. (A) Phospho-Akt immunostaining was performed in sections of small intestine from both PPARδ+/+/ApcMin/+ and PPARδ−/−/ApcMin/+ male mice treated with vehicle or GW501516 for 7 weeks. A representative section shows phospho-Akt immunoreactive staining (brown) in the epithelial cells of polyps. (Scale bar, 100 μm.) Phospho-Akt in polyps was determined by Western blot analysis as described in Fig. 3H Right). (B) TUNEL staining of small intestinal adenomas from both PPARδ+/+/ApcMin/+ and PPARδ−/−/ApcMin/+ mice treated with vehicle or GW501516. A representative section shows that apoptotic nuclei are stained brown by the DeadEnd colorimetric TUNEL system as described in Methods. (Scale bar, 100 μm.) The bar graph represents mean + SE of apoptotic cells per polyp from 30 polyps taken from three mice for each experimental group (Right).
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References

    1. Wang YX, Lee CH, Tiep S, Yu RT, Ham J, Kang H, Evans RM. Cell. 2003;113:159–170. - PubMed
    1. Tanaka T, Yamamoto J, Iwasaki S, Asaba H, Hamura H, Ikeda Y, Watanabe M, Magoori K, Ioka RX, Tachibana K, et al. Proc Natl Acad Sci USA. 2003;100:15924–15929. - PMC - PubMed
    1. Evans RM, Barish GD, Wang YX. Nat Med. 2004;10:355–361. - PubMed
    1. Oliver WR, Jr, Shenk JL, Snaith MR, Russell CS, Plunket KD, Bodkin NL, Lewis MC, Winegar DA, Sznaidman ML, Lambert MH, et al. Proc Natl Acad Sci USA. 2001;98:5306–5311. - PMC - PubMed
    1. Gupta RA, Wang D, Katkuri S, Wang H, Dey SK, DuBois RN. Nat Med. 2004;10:245–247. - PubMed

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