Hedgehog Pathway Inhibition in Liver Cancer Model Figure 2. Hedgehog (Hh) inhibitor, GDC-0449, abrogates effects of Hh signaling within liver parenchyma and HCC nodules. A. Liver sections stained for Gli2 from representative DMSO- and GDC-0449- treated mice (406). Quantitative Gli2 immunohistochemistry data in non-tumor livers of mice treated with DMSO or GDC-0449 (n = 9–10/group) are graphed as mean6SEM (**p,0.01. The number of ductular cells with Gli2 positive staining were counted in each portal tract/section under 406magnification. B. Tumor sections from the same mice were also stained to demonstrate Gli2. Results from representative DMSO- and GDC-0449-treated mice are displayed. Quantitative Gli2 immunohistochemistry data were generated by counting nuclear Gli2 positive ductular and hepatocytic cells in tumor sections under 406 magnification. Results are graphed as mean6SEM Gli2- positive cells/406 high power field (**p,0.01) C–D Quantitative reverse transcription-PCR (qRT-PCR) analysis of whole liver RNA from DMSO-(open bar) and GDC-0449 (black bar) treated mice. C. PPAR-c, a gene that is normally repressed by Hh signaling. D. Gli1, a gene that is induced by Hh signaling. Mean6SEM are graphed (**p,0.01). doi:10.1371/journal.pone.0023943.g002 MRI and histological evidence of liver tumor involution following GDC-0449 treatment To evaluate the potential impact of changes in matrix and progenitor cells on HCC, pre- and post-treatment tumor volumes were analyzed using magnetic resonance imaging (Figures 6A–B). An analysis of tumors in mice without overt metastasis demonstrat- ed that tumor volumes decreased in mice that received a 9 day course of GDC-0449-treatment, while vehicle-treated animals evidenced persistent tumor growth (Figure 6C; 26.7%+/ 211.7% vs 22.7% +/29.1%, p = 0.03). This data correlated with PLoS ONE | www.plosone.org 5 September 2011 | Volume 6 | Issue 9 | e23943