Figure 6.

Loss of Kmt2d in two models of SHH-MB promotes local cell invasion and spinal cord metastasis

(A–D″) Representative images of sagittal sections from end stage tumors stained with Hoechst (blue) and GFP (green) without tumor cell invasion into the white matter (WM) (A, A′, A″) or with tumor cell invasion into the WM (B, B′, B″), and without tumor cell invasion into the brainstem (BS) (C, C′, C″) or with tumor cell invasion into the BS (D, D′, D″). Overlayed Hoechst and GFP images of the whole cerebellum are shown in (A–D) (Scale bar: 1 mm). Overlayed Hoechst and GFP images in the specific regions indicated by rectangles in (A) are shown in (A′–D′) and single channel GFP-staining of the same regions in (A″–D″) (Scale bar: 250 μm).

(E–H) Representative sections at the rostral-caudal levels indicated of spinal cords stained with H&E from SmoM2 animals without metastasis (Scale bar: 500 μm).

(E′–H′) Adjacent sections stained with Hoechst, GFP (green) and Ki67 (red) (Scale bar: 500 μm).

(I–L) Representative sections of spinal cords stained with H&E from SmoM2-Kmt2d^Cf/Cf animals (Scale bar: 500 μm).

(I′–L′) Fluorescence images of adjacent sections stained with Hoechst, GFP (green) and Ki67 (red) (Scale bar: 500 μm). Single channel GFP (I″-L″) and Ki67 (I‴–L‴) staining of metastatic tumors in the spinal cord (Scale bar: 250 μm).

(M–O) Quantification of the percentage of sectional spinal cord area taken up by tumor in >30 sections per mouse in the SmoM2-driven model of SHH-MB with and without a Kmt2d C-terminal mutation (M) or Kmt2d N-terminal mutation (N), and in the Ptch1 model (O). Open dots indicate animals that did not show symptoms of tumor burden at P150 (SmoM2 models) or P200 (Ptch1 model) but had primary tumors. All statistical significance was determined using an unpaired t-test comparing Kmt2d wildtype tumors to each of the Kmt2d mutants. Also see Figure S7.