Figure 3.

Overexpression of AhRR in PyMT mice extends mammary tumor latency and decreases tumor incidence. (A) Kinetics of palpable tumor onset in 10 PyMT/wt and 10 PyMT/AhRR⁺ mice. Values are shown as percentage of 10 mice. (B) AhRR overexpression decreases the number of palpable lesions detected at necropsy in PyMT/AhRR⁺ compared to PyMT/wt mice. Values of 10 mice per group are shown, ^asignificantly different from PyMT/wt, P ≤ 0.001. (C) Multiplicity of Mammary Tumors in PyMT/wt and PyMT/AhRR⁺ mice at the indicated time points are shown. Mean±SEM of are shown. *Statistically significant differences were tested by Student's t-test in tumor multiplicity, P ≤ 0.001. Expression of (D) AhR, (E) AhRR, (F) COX-2, and (G) C/EBPβ mRNA levels in normal and mammary tumor tissue of PyMT/wt and PyMT/AhRR⁺ mice. ^aSignificantly higher than normal mammary tissue of PyMT/wt mice, ^bsignificantly lower than PyMT/wt tumor tissue, ^csignificantly lower than normal mammary tissue of PyMT/wt and PyMT/AhRR⁺ mice, ^dsignificantly lower than PyMT/wt normal mammary tissue. Statistical significance was tested with two-way ANOVA test (p < 0.01). (H) Representative images of immunoblotting of AhR and AhRR in normal (NT) and mammary tumor tissue (TT). (I) The band intensity was measured, and the protein levels of AhR and AhRR were divided by those of Actin to calculate the relative protein levels. The values represent the mean ± SD (n = 3) and statistics of a Student's t-test are shown. ^aSignificantly different from PyMT/wt normal tissue (p < 0.01).