Inhibition of tumor growth in an ASPL-TFE3 fusion transcript xenografts by halofuginone. (A) Halofuginone treatment inhibited tumor growth and development in xenografts derived from the FU-UR-1 cell with reciprocal ASPL-TFE3 fusion transcript. Insert: Tumors of control and halofuginone-treated mice at 33 days after FU-UR-1 cell implantation. (B) Inhibition of TFE3, myofibroblasts' activation, and Smad3 signaling in FU-UR-1 xenograft by halofuginone. At day 33 after FU-UR-1 cell implantation, tumors from control and halofuginone-treated mice were taken for histopathology analysis. Almost all of the tumor cells of the untreated mice exhibit high levels of TFE3, which was abrogated by halofuginone treatment (original magnification, x400). Halofuginone treatment inhibited the collagen and αSMA synthesis observed in the control mice (arrows; original magnification, x200) suggesting inhibition of myofibroblasts' activation. Halofuginone also inhibited the SRF and phosphorylation of Smad3 without affecting Smad3 levels (arrows; original magnification, x400).