Figure 4.
Effect of epithelial Dhps deletion on colon carcinogenesis. Dhpsfl/fl (n = 25) and DhpsΔepi mice (n = 22) were given 6 i.p. injections of 12.5 mg/kg AOM. Note that two DhpsΔepi mice died between day 119 and 127 (P = 0.132), and that none of the control animals that did not receive AOM developed tumors. (A) Body weights are depicted as percentage of initial body weight. (B-E) Colons were harvested, opened longitudinally (B) and tumors (arrow) were counted (C) and measured (D); in D, the percentages were determined from a total of 57 and 91 tumors in Dhpsfl/fl and DhpsΔepi mice, respectively. Tumor burden (E) corresponds to the sum of the surface area of all the tumors in each mouse. (F-H) H&E staining (F) was used to assess histologic injury (G) and the grade of dysplasia (H). In F, the photomicrographs in the upper panels for Dhpsfl/fl and DhpsΔepi mice show LGD and HGD, respectively; the lower panels depict an invasive carcinoma; scale bars, 50 μm. *P < .05, **P < .01, ****P < .0001 by Student’s t test; in D and H, the P values were calculated using the Chi-square test.