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

Figure 1 Upregulated expression of cathepsin L in gastric cancer patients with peritoneal metastasis. A: The general level of cathepsin L (CTSL) expression among different cancers from the Gene Expression Profiling Interactive Analysis platform in The Cancer Genome Atlas database; B and C: CTSL expression in gastric tumors (n = 408) was significantly greater than that in normal gastric tissues (n = 211) and was associated with tumor stage in the STAD dataset. The error bars represent the SD, ^aP < 0.05 according to Student’s t test; D: As a differentially expressed gene, CTSL was upregulated in GSE33651 and GSE11896 (log2fc = 1.786, log2fc = 2.162) via GEO2R analysis; E and F: The qPCR analysis of mRNAs extracted from 64 paired gastric tissues from patients at Nanfang Hospital revealed a significant increase in CTSL expression in tumor tissues (n = 64), P = 0.0412, especially in the group with metastasis (n = 12), P = 0.0434. The data points are presented as the means ± SD. The error bars represent the SD. ^aP < 0.05 according to Student’s t test; ^bP < 0.01 according to Student’s t test; G and H: Representative immunohistochemistry (IHC) images of tumor and paracancerous normal sections stained for CTSL; scale bar, 100 μm. The quantification of positively stained cells in the sections via Image J was performed via the geometric mean of 3 representative views from each section; the 53 sections from Nanfang Hospital were used in total. The error bars represent the SD; ^cP < 0.001 according to Student’s t test; I-K: Representative IHC images of tumor sections from patients with or without peritoneal metastasis stained for CTSL; the error bars represent the SD; ^aP < 0.05; ^cP < 0.001 according to Student’s t test. The quantification of positively stained cells in the sections was the same as above for 53 sections from Nanfang Hospital (with metastasis: 18 cases; without metastasis: 35 cases) and 39 sections from the Central Hospital of Wuhan (with metastasis: 9 cases; without metastasis: 30 cases) were used for each group. T: Tumor; N: Normal; PM: Peritoneal metastasis; CTSL: Cathepsin L.