Macrophage-derived cathepsin L promotes epithelial-mesenchymal transition and M2 polarization in gastric cancer

Figure 3 Cathepsin L is critical for macrophages to promote gastric tumor invasion and migration via epithelial-mesenchymal transition. A: Representative immunohistochemistry images of multinucleated giant cells stained for cathepsin L (CTSL) in gastric tumor sections. Magnification, 40 ×; B: Immunofluorescence analysis of CTSL and CD68 in the tumor tissue of gastric cancer patients; scale bar, 20 mm; C: The qPCR and Western blot analysis of shCTSL-treated THP-1 cells. The error bars represent the SD; NS: P > 0.05; ^cP < 0.001; ^bP < 0.01 according to one-way analysis of variance (ANOVA); D: Invasion assay of the gastric cancer cell lines MKN45 and MGC803 cocultured with shCTSL or shNC THP-1 cells. Magnification, 20 ×. The chemotactic cells that migrated through the Matrigel in the five views of each group were quantified manually. The error bars represent the SD; ^bP < 0.01; ^cP < 0.001; ^dP < 0.0001 according to one-way ANOVA; E: Wound healing assay of the gastric cancer cell lines MKN45 and MGC803 cocultured with shCTSL or shNC THP-1 cells for 48 hours. Magnification, 4 ×. The wound closure area was quantified via Image J via data from 3 independent experiments. The error bars represent the SD; ^bP < 0.01; according to Student’s t test; F: Western blot analysis of E-cadherin levels in various gastric cancer cell lines; G: Western blot analysis of epithelial-mesenchymal transition-related proteins (E-cadherin, β-catenin, N-cadherin, and Snail) in MKN45 and MGC803 cells cocultured with shCTSL or shNC-transfected THP-1 cells for 48 hours. Blots from three independent experiments were quantified via Image J. The error bars represent the SD; ^cP < 0.001; ^bP < 0.01; ^aP < 0.05 according to one-way ANOVA. CTSL: Cathepsin L; DAPI: 4',6-diamidino-2-phenylindole.