Figure 4.

HTR1E inhibits SRC-mediated pathways that promote cell proliferation and EMT. (A) Hypothesized signaling pathways triggered by serotonin/HTR1E based on GSEA analysis. (B) Western blot analysis of the activation of SRC in shHTR1E or shCtrl SK-OV-3 cells. (C) Western blot analysis of the activation of SRC and ERK in SK-OV-3 cells in the presence of serotonin and SRC inhibitor (SRCi, 1 µM) or MEK inhibitor (MEKi, 1 µM). (D) Cell proliferation curves of SK-OV-3 cells in the presence of serotonin (5 µM) with or without SCRi (1 µM) or MEKi (1 µM) (means ± SEM from three independent experiments, ***P < 0.001, by two-way ANOVA test). (E) Colony formation assays of SK-OV-3 cells in the presence of serotonin with or without SCRi (1 µM) or MEKi (1 µM) (means ± SEM from three independent experiments, ***P < 0.001, ns not significant, by unpaired, two-tailed student's t-test). (F) Western blot analysis of EMT markers in indicated SK-OV-3 cells in the presence of serotonin and SRCi (1 µM). (G) The motility of indicated SK-OV-3 cells in the presence of serotonin and SRCi (1 µM) analyzed by High-Content Imaging and Harmony analysis system (means ± SEM from three independent experiments, ***P < 0.001, ns not significant, by unpaired, two-tailed student's t-test). (H-I) Western blot (H) and IHC (I) analysis of the EMT markers and the activation of SRC and ERK in the primary OC xenografts (Pri) and the peritoneal metastases (Met) dissected from the SK-OV-3 orthotopic murine model of OC. The quantification by H score method is analyzed by paired, two-tailed student's t-test (n = 6, *P < 0.05, ***P < 0.001). (J) IHC analysis of human primary OC specimens (Pri) and paired peritoneal metastases (Met) for HTR1E and EMT markers. The correlation between HTR1E and EMT markers is analyzed by paired, two-tailed student's t-test (n = 13, ***P < 0.001).