Inhibition of FGFR signaling suppresses tumor lymphangiogenesis and VEGF-C expression.

Abstract

<p>(A) Left Panel, 66c14 tumor cells are observed into the lumens of VEGFR-3-positive lymphatic vessels (green) in 66c14 control tumors (white arrows in both left image and right zoomed-inset). Right panel, cytokeratin-stained 66c14 tumor cells (green) are detectable in axillary lymph nodes of 66c14 control cells-bearing mice (white arrows in both left image and right zoomed-inset), confirming the invasion mechanism via the lymphatic system of the 66c14 cells. (B) Left panel, representative images of VEGFR-3 (green) and DAPI (blue) staining of parental, empty plasmid (Control) and FGFR-2DN-expressing 66c14 tumors sections. White arrows indicate lumenized lymphatic vessels or isolated lymphatic endothelial cells in controls (Control and Parental) and FGFR-2DN tumors, respectively. Right panel, quantification of VEGFR-3-positive lymphatic vessel density (VD) demonstrates a density decrease in FGFR2-DN (R-2DN) expressing 66c14 tumor as compared to parental (Par.) or control (Ctrl) tumors. (C) Upper panel, FGFR-2DN-expressing 66c14 (66c14 FGFR-2DN) tumors exhibit a decrease in podoplanin-positive lymphatic vessel (green) density compared to control groups (66c14 Control and Parental). White arrows confirm the presence of lumenized lymphatic vessels or isolated lymphatic endothelial cells in controls and FGFR-2DN tumors, respectively. Bottom panel, quantification of podoplanin-positive lymphatic vessel density (VD) confirms a density decrease in FGFR2-DN (R-2DN) expressing 66c14 tumor as compared to parental (Par.) or control (Ctrl) tumors. (D) VEGF-C and PDGF-B (black and white bars, respectively) mRNA quantification of 66c14 tumor by qRT-PCR shows uniquely a VEGF-C expression decrease in 66c14 FGFR-2DN-expressing (R-2DN) versus control tumors (Ctrl; 66c14 control and Par; parental). (Scale Bars, 200 µm in A–C, *p<0.05 versus respective control groups).</p