Fig. 10
AHR down-regulation decreases tumor formation in xenograft mice. (a) Doxycycline-inducible shAhr-expressing SUM149 cells were sorted for ALDHhigh or ALDHlow activity and 3,000 cells were grafted into the mammary fat pads of NOD/SCID mice (10 mice/group). Tumor volumes were measured over the next 56 days. Data are presented as mean tumor volume ± standard error; P <0.0001. The average rate of tumor growth of tumors initiated with ALDHhigh cells (0.26 mm/day) was significantly different than the rate of growth of tumors initiated with ALDHlow cells (0.19 mm/day), P <0.0005. A cross indicates a significant increase in average tumor size beginning at day 25, + P <0.01. (b) Doxycycline-inducible shAhr-expressing SUM149 cells were sorted for low ALDH expression and 3,000 cells were grafted into the mammary fat pads of NOD/SCID mice. Mice then were given water + 5 % sucrose or water with doxycycline + 5 % sucrose and tumor volumes were quantified over the next 56 day period. The average rate of tumor growth of ALDHlow cells in control mice (0.19 mm/day) was significantly different than that of ALDHlow cells in dox-treated mice (0.11 mm/day), P <0.0005. (c) Doxycycline-inducible shAhr-expressing SUM149 cells were sorted for high ALDH expression and 3,000 cells were grafted into the mammary fat pads of NOD/SCID mice. Mice were then given water + 5 % sucrose or water with doxycycline + 5 % sucrose. Tumor volumes were measured over the next 56 day period. The average rate of tumor growth in water-treated control mice (0.26 mm/day) was significantly different than the rate of tumor growth in dox-treated mice (0.18 mm/day), P <0.0005. A cross indicates a significant increase in tumor size beginning at day 25, + P <0.01