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Results: 5

1.
Figure 4

Figure 4. Lowering oxygen exposure prevents DNA damage and β-catenin accumulation in the intestine.. From: Ambient Oxygen Promotes Tumorigenesis.

A. Decreased oxidative DNA damage as measured by 8-oxoG (pg/µg genomic DNA) ELISA in polyp-free segments of intestine from 10% compared to 21% oxygen APCMin/+ mice. Data shown as mean ± SEM, with n = 3. B. Decreased DNA damage response observed by γ-H2AX western blotting in polyp-free intestine of 10% compared to 21% oxygen APCMin/+ mice. Relative intensity quantified by densitometric scanning of γ-H2AX normalized to β-actin protein (graph), n = 3. C. Decreased protein levels of β-catenin and its transcriptional target cyclin D1 in polyp-free intestine of 10% compared to 21% oxygen APCMin/+ mice. Representative samples in each oxygen condition and β-actin serves as protein loading control, n = 3.

Ho Joong Sung, et al. PLoS One. 2011;6(5):e19785.
2.
Figure 3

Figure 3. Ambient oxygen promotes tumorigenesis in APCMin/+ mice.. From: Ambient Oxygen Promotes Tumorigenesis.

A. Significant decrease in the total number of small intestinal polyps per mouse in 19 wk old APCMin/+ mice that were placed in 10% versus 21% oxygen for 14 wk, starting at 5 wk of age. Data shown as mean ± SEM, with n = 12. B. Decreased smaller diameter polyps (black arrowheads) in representative intestinal segments from mice in 10% compared to 21% oxygen. C. Quantification of polyps classified by size (polyp diameter, mm) in 10% versus 21% oxygen. The relative reduction in polyp number in 10% versus 21% oxygen is greatest for the smallest diameter polyps (<1.5 mm). Data shown as mean ± SEM, with n = 12.

Ho Joong Sung, et al. PLoS One. 2011;6(5):e19785.
3.
Figure 1

Figure 1. Ambient oxygen promotes tumorigenesis in p53−/− mice.. From: Ambient Oxygen Promotes Tumorigenesis.

A. p53−/− mice show increased median tumor-free survival time in 10% compared to 21% ambient oxygen by Kaplan-Meier survival analysis. After weaning in 21% oxygen (normoxia, room air), the p53−/− mice either remained in normoxia or were transferred to standard-sized mouse cages in a large 10% oxygen (hypoxia) chamber. Tumor-free survival period was defined as time to death with tumor diagnosis at necropsy or to an external tumor exceeding 2 cm in any dimension per institutional animal care and use committee guidelines (10% oxygen, n = 20; 21% oxygen, n = 14). B. Arterial oxygen saturation is proportional to ambient oxygen after acclimation indicating absence of significant supply-demand mismatch (partial pressure of oxygen, PO2). Data are shown as mean ± SEM, with n = 5. C. Decreased ambient oxygen does not inhibit the growth of p53+/+ HCT116 cancer cell as xenografts. 10×106 cells were injected into the contra-lateral hind limbs of athymic nude mice and immediately placed in their respective ambient oxygen conditions. Xenograft tumor growth was monitored over the time as shown (n = 10 each). D. Decreased ambient oxygen does not inhibit the growth of p53−/− HCT116 cancer cell as xenografts (n = 10 each).

Ho Joong Sung, et al. PLoS One. 2011;6(5):e19785.
4.
Figure 2

Figure 2. Lowering oxygen exposure reduces oxidative stress, DNA damage and genomic instability in thymus.. From: Ambient Oxygen Promotes Tumorigenesis.

A. Changes in reduced (GSH) and oxidized (GSSG) glutathione levels show increased antioxidant capacity in blood of mice after chronic adaptation to the 10% oxygen condition. Data shown as mean ± SEM, with n = 4. B. Decreased ROS levels measured by DCF FACS in cells isolated from the thymus of mice in 10% oxygen. Data shown as mean ± SEM, with n = 5. C. Representative images of decreased oxidative DNA damage detected by avidin-FITC (Av-FITC) staining for 8-oxoG in thymus tissue from p53−/− mouse exposed to 10% versus 21% oxygen for 2 to 4 wk. Nuclei counterstaining with DAPI show similar densities in the tissue. Scale bar, 100 µm (originally 63× magnification). D. Decreased oxidative DNA damage quantified by 8-oxoG enzyme-linked immunosorbent assay (ELISA) in thymus tissue from p53−/− mice exposed to 10% compared to 21% oxygen. Absolute value of 8-oxoG (pg/µg genomic DNA) shown as mean ± SEM, with n = 3. E. Increased relative telomere length measured by RT-PCR of genomic DNA from thymus tissue of p53−/− mice exposed to 10% versus 21% oxygen. Data shown as mean ± SEM, with n = 3. F. Decreased RAG1 protein level measured by western blotting in 10% versus 21% oxygen. Samples shown are from two separate animals in each oxygen condition and β-actin serves as protein loading control.

Ho Joong Sung, et al. PLoS One. 2011;6(5):e19785.
5.
Figure 5

Figure 5. Ambient oxygen promotes chemical skin carcinogenesis.. From: Ambient Oxygen Promotes Tumorigenesis.

A. Decreased skin papilloma formation using the two-stage chemical skin carcinogenesis model in 10% compared to 21% ambient oxygen. Representative images are shown for standard (5 µg) or high (100 µg) topical dose of DMBA followed by chronic TPA application. B. Decreased papilloma number per mouse in 10% compared to 21% oxygen. Data shown as mean ± SEM, with n = 10 to 15. C. Increased median survival time to tumor endpoint in 10% compared to 21% oxygen by Kaplan-Meier survival analysis. The standard dose of DMBA followed by chronic TPA application was used until the defined tumor endpoint of papilloma size(s) exceeding 2 cm in any dimension, significant ulceration or rupture of tumor, moribound state, or death. 10% oxygen, n = 10; 21% oxygen, n = 10. D. Decreased oxidative DNA damage quantified by 8-oxoG ELISA in DMBA treated skin tissue of mice in 10% compared to 21% oxygen. DMBA (100 µg) and TPA (12.5 µg) were applied according to skin per protocol, animals were exposed to the indicated oxygen conditions, and skin tissue was harvested prior to the development of papillomas at 7 wk. Absolute value of 8-oxoG (pg/µg genomic DNA) shown as mean ± SEM, with n = 3. E. Confirmation of decreased DNA damage by protein levels of γ-H2AX in skin tissue from treated mice in 10% compared to 21% oxygen. β-actin serves as protein loading control and samples are shown from two separate animals for each condition as duplicates.

Ho Joong Sung, et al. PLoS One. 2011;6(5):e19785.

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