Fig 1: Effects of FG-3019 on CTGF expression and fibrosis(A) CTGF expression of tumor cells. Tumor (mesothelioma) cells were diffusely positive for CTGF. Degree of CTGF immunostaining in tumor cells (CTGF score) was evaluated as follows: 0, no staining or no mesothelioma cells; 1, weak; 2, moderate; 3, strong. CTGF score of FG-3019 + PEM group was lower than IgG + PEM group. (B) CTGF expression of stromal cells. For judging stromal portion in tumor (dotted line), we used H&E staining and immunohistochemical staining of calretinin (calretinin is a positive marker for mesothelioma). Stromal cells were negative for calretinin and spindle shaped (mesothelioma cells were cuboidal). Stromal cells were sporadically positive for CTGF, so we calculated the percentage of CTGF-positive stromal cells. The percentage of FG-3019 + PEM group was lower than the other group. (C) Tumor fibrosis (Elastica-Masson staining). Fibrosis, which is shown as light green positive, was quantified with ImageJ as described in Materials and Methods. FG-3019 + PEM significantly decreased the fibrosis of tumor. N = 6 (IgG), N = 6 (FG-3019), N = 6 (IgG + PEM), N = 6 (FG-3019 + PEM) in (A)–(C); means ± SEM, *P < 0.05. N is the number of mice used. Pathological specimens generated for each mouse and analyzed. Bar; 50 μm in (A), 100 μm in (B), 200 μm in (C). N.S., not significant.
Fig 2: CTGF expression in human mesothelioma cell lines(A) Western blot analysis. Antibody 14939 (Santa Cruz Biotechnology; 1:200) was used to detect CTGF at 36-38 kDa. All the cell lines examined expressed CTGF, but several cell lines expressed low levels of CTGF, irrespective of histological subtypes. Three cell lines (ACC-MESO-4, Y-MESO-8D and NCI-H290) were chosen for the following experiments. ACC-MESO-4 and NCI-H290 are epithelioid subtype, and Y-MESO-8D is sarcomatoid subtype. (B) Semiquantitative analysis of western blot analysis. Relative CTGF expression in comparison to MeT-5A was calculated with ImageJ. N = 3; means ± SEM, **P < 0.01, ***P < 0.001.
Fig 3: Summary schemeFG-3019 attenuated proliferation and induced apoptosis both in mesothelioma cells and stromal cells. FG-3019 may target both autocrine and paracrine CTGF effects on mesothelioma and stromal cells. Light blue circles indicate CTGF.
Fig 4: Co-culture experiments using mesothelioma cell lines and fibroblasts(A) Proliferation assay. NHLF promoted proliferation of mesothelioma cells. (B, C) Migration/Invasion assay. NHLF promoted migration and invasion of mesothelioma cells. (D) Western blot analysis. CTGF expression in ACC-MESO-4 was significantly increased upon co-culture. NHLF also expressed CTGF. N = 3 for each group in (A)-(C) and N = 4 in (D); means ± SEM, *P < 0.05, **P < 0.01, ***P < 0.005. NHLF, normal human lung fibroblast.
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