Fig. 1.
Myc activation leads to rapid reorganization of the tumor and its stroma, while limiting growth through tumor-suppressive pathways. All tumors were analyzed after 3 d of sustained treatment with tamoxifen (100 μg/mouse, twice daily) or oil (vehicle) for the respective controls. Abbreviations in graphs: C, controls; M, MycerT2 plus tamoxifen. Error bars represent SD. (A) Gross morphological features and histological appearance of WM+T tumors compared to controls (controls in all following experiments are as follows: WM−T plus tamoxifen and plus vehicle; WM+T plus vehicle). (B) Cellularity of WM+T tumors and controls (n = 6/9, respectively). (C) Quantification of necrosis of WM+T tumors and controls (n = 6/9, respectively). (D) Quantification of hypoxia in WM+T tumors and controls (n = 6/9, respectively). (E) Average area of blood vessel, in WM+T tumors and controls (n = 6/9, respectively). (F) Caliperimetric measurement of tumor growth of WM+T tumors and controls, as percentage change from start of treatment (n = 6 WM+T tumors and 11 controls). (G) Quantification of proliferation, by IDU incorporation, in WM+T tumors and controls (n = 7/14 respectively). (H) Quantification of cell death, by presence of cleaved caspase 3, in WM+T tumors and controls (n = 6/9, respectively). (I) WB analysis of p53 and actin as a loading control in whole-tissue lysates of 2 representative WM+T tumors and controls. Bands were quantified by comparison with the loading control and are represented as fold change relative to average of the control tumors. (J) Quantitative real-time PCR of whole-tissue mRNA extracts from WM+T tumors and controls for indicated genes and GAPDH as a housekeeping gene (n = 6/11, respectively). (K) Representative immunofluorescent staining for p19ARF (red), EGFP (green), and DNA (Hoechst; blue), of WM+T tumors and controls (n = 6/9, respectively). For box-and-whisker plots, the error bars represent min to max values, the box represents the interquartile range, and the horizontal line represents the median. P values are based on Student’s t test: n.s., not significant; *P < 0.05, **P < 0.01, and ***P < 0.001.