Calcitriol Inhibits Hedgehog Signaling and Induces Vitamin D Receptor Signaling and Differentiation in the Patched Mouse Model of Embryonal Rhabdomyosarcoma
Figure 2
Calcitriol inhibits Hh signaling and proliferation and induces Vdr signaling and differentiation of ERMS in Ptch neo67/+ mice in vivo. (a) Calcitriol treatment scheme and calcium serum concentrations of ERMS-bearing Ptch neo67/+ mice. Animals were either sacrificed directly at therapy end (8 weeks of treatment) or after an additional 4-week observation period (dashed arrow). (b) Tumor volume was determined by VCT analysis before therapy (before), at the end of therapy (8 weeks), and 4 weeks thereafter ( weeks). Given is the relative median tumor size (horizontal bars) for each time point, the individual tumor volumes (dots), and the standard deviation of tumor volumina. ERMS treated with calcitriol (black) or vehicle (grey). Median tumor volume before onset of treatment was set as 1. Median of the absolute tumor volumes at time point of randomization was 0.011 cm3 ±SEM 0.0033. (c) Gli1, Cyp24a1, and Vdr, (d) MyoD1, MRF4, and p27 expression levels and (e) percentages of Ki67+ tumor cells/all tumor cells of ERMS after calcitriol-treatment for 8 weeks (8 weeks) or after the additional 4-week observation period ( weeks) compared to vehicle-treated tumors (vehicle). Expression levels were normalized to the expression of 18S rRNA gene. Values of vehicle-treated controls for Gli1, Vdr, MyoD1, MRF4, and p27 expression were set to 1. Values of vehicle-treated controls for Ki67+ tumor cells were set to 100%. Asterisks: ; error bars: mean ± SD.
