Expression of FOXM1 promotes mucinous characteristics in mouse lung tumors induced either by urethane or Kras^G12D.

<p><b>(A)</b> Lung sections form urethane-treated mice (control n = 6 and <i>epiFoxM1-ΔN</i> n = 9 mice) were stained with antibodies against Nkx2-1 and Alcian blue. Tumors in <i>epiFoxM1-ΔN</i> mice were highly positive for mucus (blue) and had low Nkx2-1 protein levels (brown). <b>(B)</b> <i>Nkx2-1</i> mRNA was decreased in microdissected <i>epiFoxM1-ΔN</i> tumors (n = 5) compared to control tumors (n = 5) as shown by qRT-PCR. <i>β-actin</i> mRNA was used for normalization. Data represent mean ± SD of three independent determinations using micro-dissected lung tumors from n = 6 control mice and n = 9 <i>epiFoxM1-ΔN</i> mice. <b>(C)</b> Co-localization studies demonstrated decreased Nkx2-1 in FoxM1-ΔN-positive tumor cells. <b>(D)</b> Tumors from epiFoxM1-ΔN mice stained positive for Muc5B and Muc5Ac as shown by immunofluorescence staining. <b>(E)</b> Parafin section from <i>Kras</i>^<i>G12D</i>-induced lung tumors <i>(SPC-rtTA/TetO-Kras</i>^<i>G12D</i> mice, n = 3) and <i>Kras</i>^<i>G12D</i><i>; epiFoxM1-ΔN</i> mice (<i>SPC-rtTA/TetO-Kras</i>^<i>G12D</i><i>/TetO-FoxM1-ΔN</i> mice, n = 3) were stained with Alcian blue. FoxM1-ΔN caused mucus depositions in lung tumors induced with <i>Kras</i>^<i>G12D</i>. A p-value <0.05 is marked with an asterik (*).