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. 2017 Aug 17;67(4):685-701.e6.
doi: 10.1016/j.molcel.2017.07.014. Epub 2017 Aug 10.

V体育2025版 - Paraoxonase 2 Facilitates Pancreatic Cancer Growth and Metastasis by Stimulating GLUT1-Mediated Glucose Transport

Arvindhan Nagarajan  1 , Shaillay Kumar Dogra  2 , Lisha Sun  1 , Neeru Gandotra  3 , Thuy Ho  1 , Guoping Cai  1 , Gary Cline  4 , Priti Kumar  5 , Robert A Cowles  3 , Narendra Wajapeyee  6
Affiliations

"VSports手机版" Paraoxonase 2 Facilitates Pancreatic Cancer Growth and Metastasis by Stimulating GLUT1-Mediated Glucose Transport

Arvindhan Nagarajan et al. Mol Cell. .

Abstract

Metabolic deregulation is a hallmark of human cancers, and the glycolytic and glutamine metabolism pathways were shown to be deregulated in pancreatic ductal adenocarcinoma (PDAC). To identify new metabolic regulators of PDAC tumor growth and metastasis, we systematically knocked down metabolic genes that were overexpressed in human PDAC tumor samples using short hairpin RNAs. We found that p53 transcriptionally represses paraoxonase 2 (PON2), which regulates GLUT1-mediated glucose transport via stomatin VSports手机版. The loss of PON2 initiates the cellular starvation response and activates AMP-activated protein kinase (AMPK). In turn, AMPK activates FOXO3A and its transcriptional target, PUMA, which induces anoikis to suppress PDAC tumor growth and metastasis. Pharmacological or genetic activation of AMPK, similar to PON2 inhibition, blocks PDAC tumor growth. Collectively, our results identify PON2 as a new modulator of glucose transport that regulates a pharmacologically tractable pathway necessary for PDAC tumor growth and metastasis. .

Keywords: GLUT1; PON2; anoikis; glucose; metabolism; pancreatic cancer V体育安卓版. .

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Figures (VSports手机版)

Figure 1
Figure 1. Integrative genomics approach identifies metabolic genes necessary for pancreatic ductal adenocarcinoma (PDAC) growth
A. Schematic of the analysis to identify genes necessary for PDAC tumor growth. B. Representative images show soft-agar colony formation by PDAC cell lines expressing PON2 or nonspecific (NS) shRNAs. C. PANC1 cells expressing PON2 or NS shRNAs were injected subcutaneously and analyzed for tumor formation in athymic nude mice (n=5). Average tumor volumes are shown. D. PANC1 cells expressing PON2 or NS shRNAs were injected orthotopically into the pancreas of athymic nude mice (n=3) and analyzed for tumor formation. Representative bioluminescence images are shown. E. Representative images show soft-agar colony formation in the absence or presence of doxycycline (left) or average tumor volume in mice (n=5) in the presence of doxycycline (right) using iKRAS mouse model-derived pancreatic cancer cells that were engineered to express empty vector or PON2 cDNA. F. Representative images show soft agar-colony formation (top) or average tumor volume in mice (n=5) (bottom) using human HPNE-hTERT E6/E7/st cells that express empty vector or PON2 cDNA. Data are mean ± SEM. **p<0.05. See also Figure S1, Figure S2, Table S2 and Table S3.
Figure 2
Figure 2. Loss of PON2 results in anoikis induction and metastasis inhibition
A. PDAC cell lines expressing PON2 or nonspecific (NS) shRNAs were seeded on poly(HEMA)-coated plates. Viable cells were counted after staining with trypan blue, and the relative numbers of viable cells are plotted at the indicated times. B. PANC1 cell lines expressing the indicated shRNAs were analyzed for apoptosis under attached and detached conditions by flow cytometry after staining with annexin V-FITC and propidium iodide. Percentage of annexin V-FITC-positive cells (attached and detached) after treatment with Z-VAD-FMK (10 μM) is shown. C. PANC1 cells expressing PON2 or NS shRNAs were grown under attached or detached conditions. Detached cells were either left untreated or treated with Z-VAD-FMK (10 μM). Cell lysates were analyzed for PARP cleavage by immunoblot analysis. ACTINB was used as a loading control. D. Athymic nude mice (n=3) were injected with PANC1 cells expressing PON2 or NS shRNAs via the tail vein. Lung metastasis was monitored by bioluminescence imaging. Representative images are shown at week 1 and week 4. E. Athymic nude mice (n=3) received intrasplenic injections of luciferase-tagged PANC1 cells expressing either PON2 or NS shRNA to cause liver metastasis. Metastatic tumor growth in the livers was visualized after 6 weeks. Bioluminescence images of livers isolated from the mice are shown. F. Luciferase-tagged PANC1 cells carrying PON2 or NS shRNA were injected into the pancreases of athymic nude mice (n=3). Spontaneous metastasis to the livers and lungs was visualized after 6 weeks. Bioluminescence images of livers and lungs isolated from the mice are shown. G. qPCR analysis of circulating tumor cells originating from primary tumors formed by injecting PANC1 cells carrying PON2 or NS shRNA into the pancreas of athymic nude mice (n=3). Data are mean ± SEM. *p<0.05, **p<0.005. See also Figure S3, Table S2 and Table S3.
Figure 3
Figure 3. Tumor suppressor p53 transcriptionally represses PON2
A. Analyses of PON2 mRNA levels of normal pancreatic tissues and PDAC tumor samples from four indicated studies in the Oncomine database. B. Immunohistochemistry analyses of PON2 levels in normal pancreatic tissue and PDAC tumor samples. Corresponding H&E staining is shown in the top panel. C. Transcript levels of p21 and PON2 in AsPC-1 cells infected with adenovirus expressing p53 (Ad-p53) or control adenovirus expressing the β-galactosidase gene (Ad-LacZ) were evaluated by qRT-PCR. D. AsPC-1 cells infected with Ad-p53 or Ad-LacZ were analyzed for the indicated proteins by immunoblotting. E. (left) Schematics showing the p53 binding site on the PON2 promoter. (right) PON2 promoter-firefly luciferase reporters, with intact or mutated p53 binding sites, were transfected into AsPC-1 cells along with adenovirus expressing LacZ or p53-GFP. Luciferase activity was measured after 48 h and is presented as relative luciferase units. F. AsPC-1 cells expressing Ad-p53 or Ad-LacZ were analyzed using the ChIP assay to evaluate the binding of p53 to the PON2 promoter. G. Transcript levels of p53, p21, and PON2 in HPNE cells carrying p53 or nonspecific (NS) shRNA were evaluated by qRT-PCR. H. Immunoblot analyses of the indicated proteins in HPNE cells carrying p53 or NS shRNAs. I. ChIP assay to measure p53 binding on the PON2 promoter using IgG or anti-p53 antibody. The ACTINB, GAPDH, and p21 promoters were used as controls. Data are mean ± SEM. *p<0.05, **p<0.005.
Figure 4
Figure 4. Loss of PON2 activates FOXO3→PUMA-mediated apoptotic pathway to suppress tumor growth
A. ATP/ADP and ATP/AMP ratios were determined in AsPC-1 and PANC1 cells expressing PON2 or nonspecific (NS) shRNAs by LC-MS/MS. Absolute ATP/ADP and ATP/AMP ratios are plotted. B. Immunoblot analysis of PUMA, PON2, and ACTINB in PANC1 and AsPC-1 cells expressing PON2 or NS shRNAs. C. PUMA expression was assessed by qRT-PCR (left) and immunoblotting (right) in cells carrying the indicated shRNAs grown under attached or detached conditions. D. Luciferase assay using the PUMA promoter-firefly luciferase reporter with wild type or mutated FOXO1 binding site in PANC1 cells expressing PON2 or NS shRNAs in attached and detached conditions. Inset shows the location and sequence of the forkhead response element (FHRE) in the PUMA promoter E. ChIP assay to evaluate FOXO3A binding to the PUMA promoter in PANC1 cells carrying PON2 or NS shRNAs. Relative fold enrichment of FOXO3A on PUMA promoter under indicated conditions is shown. F. Immunoblot analyses of indicated proteins in PANC1 cells expressing PON2 or NS shRNAs under attached and detached conditions. G. Immunoblot analyses of the indicated proteins in PANC1 (left) or AsPC-1 (right) cells expressing PON2 or NS shRNAs with DMSO or AMPK inhibitor (AMPKi), Compound C (10 μM), treatment for 24 h. Data are presented as mean ± SEM. *p<0.05. See also Figure S4.
Figure 5
Figure 5. PON2 regulates the cellular starvation response by regulating GLUT1 activity via STOM
A. Glucose 6-phosphate/taurine ratio in PANC1 cells expressing PON2 or nonspecific (NS) shRNAs. B. Relative [14C]-2-DG uptake in PANC1 cells expressing PON2 or NS shRNAs. C. Oxygen consumption rate expressed as pmol/min in PANC1 cells expressing PON2 or NS shRNAs. D. Extracellular acidification rate (ECAR) expressed as mpH/min in PANC1 cells expressing PON2 or NS shRNAs. E. Co-immunoprecipitation assay in PANC1 cells using IgG or anti-PON2 antibody. Immunoprecipitates and lysates were analyzed for the indicated proteins. F. Relative [14C]-2-DG uptake in PANC1 cells co-expressing GLUT1 along with vector or PON2. G. Relative [14C]-2-DG uptake in a glucose competition assay in PANC1 cells expressing PON2 or NS shRNAs. H. Relative [14C]-2-DG uptake in PANC1 expressing STOM or PON2 and STOM or NS shRNAs. I. Co-immunoprecipitation assay in PANC1 cells expressing NS or PON2 shRNAs using IgG or anti-STOM antibody. Immunoprecipitates and lysates were analyzed for the indicated proteins. J. Immunoblot analysis to measure indicated proteins in PANC1 cells expressing PON2, PON2 and STOM, or NS shRNAs. K. Soft-agar colony formation by PANC1 cell lines expressing PON2, PON2 and STOM, or NS shRNAs. Data are presented as mean ± SEM. *p<0.05, **p<0.005. See also Figure S5, Figure S6 and Table S2.
Figure 6
Figure 6. PON2 inhibits FOXO3-mediated induction of PUMA transcription to promote tumor growth and anoikis resistance
A. Subcutaneous tumor formation in athymic nude mice following injections of PANC1 cells carrying the indicated shRNAs. B. Anoikis assay measuring the proliferation of PANC1 cells carrying the indicated shRNAs in poly(HEMA)-coated plates. Live cell counts on the indicated days are shown. C. Immunoblot assay to measure PARP cleavage in PANC1 cells carrying the indicated shRNAs. D. Lung metastasis imaging following tail veil injection of luciferase-tagged PANC1 cells carrying the indicated shRNAs in athymic nude mice (n=3). Bioluminescence images at week 1 and week 4 under indicated conditions are shown. E. Immunoblot analysis to measure phosphorylated AMPK levels in PANC1 cells expressing PON2 or nonspecific (NS) shRNAs in DMEM supplemented with the indicated concentrations of glucose (top) or 10 mM pyruvate or succinate (Bottom). Total AMPK was used as a control. F. Soft-agar colony formation by PANC1 cell lines expressing PON2 shRNA or NS shRNA (left) grown in regular DMEM with 25 mM or 75 mM glucose. Data are presented as mean ± SEM. *p<0.05, **p<0.005. See also Figure S7 and Table S2.
Figure 7
Figure 7. The PON2→AMPK→FOXO3A→PUMA Pathway is pharmacologically tractable for PDAC Treatment
A. PANC1 cells expressing doxycycline-inducible PON2 or nonspecific (NS) shRNAs were injected into athymic nude mice (n=3) via the tail vein, and lung metastases were allowed to form. After 1 week, one group of mice was given water-containing doxycycline (20 μg/ml), and the other group was given regular water (without doxycycline). Representative images at week 1 and week 4 are shown. B. Soft-agar colony formation of PANC1 or AsPC-1 cells was evaluated after treatment with 500 μM metformin or PBS (control). Representative wells are shown. C. PANC1 cells (1×106) were injected subcutaneously into the flank of athymic nude mice (n=5). The mice were then treated with either vehicle or the indicated doses of metformin by oral gavage once a day for 2 weeks. Tumor volumes were measured at the indicated time points. D. Soft-agar colony formation of PANC1 or AsPC1 cells was evaluated after treatment with 5 mM AICAR or PBS (control). Representative wells are shown. E. PANC1 cells (1×106) were injected subcutaneously into the flanks of athymic nude mice (n=5). The mice were then treated with either vehicle or the indicated dose of AICAR by intraperitoneal injections once a day for 3 weeks. Tumor volumes were measured at the indicated time points. F. PDAC cells expressing constitutively active AMPK (AMPK-CA) were analyzed for anchorage-independent growth by a soft-agar assay. Representative images under the indicated conditions are shown. G. Model showing the mechanism by which PON2 promotes PDAC tumor growth and metastasis. Data are presented as mean ± SEM. **p<0.005. See also Figure S7, Table S2 and Table S3.
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