Fig 2: Levels of SNTB1 mRNA and protein in colorectal cancer tissues. a SNTB1 mRNA expression in CRC tissues (T: n=79) and non-cancerous colorectal tissues (N: n=15) on the CRC cDNA chip was analyzed by qPCR. GAPDH was used as an internal control. *P < 0.05. b, c SNTB1 mRNA expression in CRC tissues (T) and non-cancerous colorectal tissues (N) from GEO (b) and TCGA (c) were analyzed. d, e SNTB1 protein expression in CRC tissues (T) and non-cancerous colorectal tissues (N) was determined by immunohistochemistry of a tissue microarray. Representative images were taken at magnification of 40× or 200× (right panel); the IHC score was calculated as intensity score × percentage score (left panel, see Methods). *P < 0.05. f, g Kaplan-Meier plots of survival of CRC patients, stratified by SNTB1 mRNA expression based on cDNA array (f) and TCGA database (g). Survival was analyzed with log-rank test

Fig 3: Gene expression profiling and high content screening suggest carcinogenic potential of SNTB1 in CRC. a Differentially expressed genes (DEGs) were analyzed from our previous microarray analysis between 14 pairs of colorectal cancer (CRC) tissues (T) and adjacent normal tissues (N). Heatmap of the 8 selected DEGs mRNA expression levels are presented. Blue color indicates low expression and red color high expression. b HCT116 cells were transduced with lentivirus encoding shRNAs against these 8 DEGs (SNTB1, PLEKHG4, JPH1, CTPS1, LRRC6, LY6G6F, PLCB4 and LRP8), and cell growth was measured using the using the Pathway 855 high-content image analysis platform. The representative images were taken at a magnification of 200×. c Heatmap showing the growth of HCT116 cells. Data were normalized to cell number on day 1 and represented as fold change

Fig 4: SNTB1 knockdown inhibits colorectal cancer (CRC) cell growth. HCT116 and RKO cells were transduced with lentivirus encoding either anti-SNTB1 small hairpin RNA (sh-SNTB1) or control shRNA (sh-Ctrl). a The mRNA levels of SNTB1 were determined by qPCR, GAPDH was used as an internal control. *P < 0.05. b, c The protein levels of SNTB1 were determined by Western-blot analysis. The representative images of SNTB1 and GAPDH are shown (b) and were quantitated using ImageLab software (c). GAPDH was used as an internal control and normalized to GAPDH. *P < 0.05. d The cell viability of CRC cells was determined by the CCK-8 assay. Data were normalized to the viability on Day 1 and are represented as fold change. *P < 0.05. e The colony formation assay was performed to determine cell survival. The images were obtained and the number of colonies formed were determined and normalized to the survival of control cells. *P < 0.05

Fig 5: SNTB1 knockdown inhibits cell proliferation and induces cell apoptosis in vivo. IHC was performed to detect SNTB1 (a) and PCNA (b) expression in tumor sections, and TUNEL assay (c) was used to determine the apoptotic cells in tissues of both sh-Ctrl and sh-SNTB1. The representative images of IHC analysis or TUNEL assay were taken at a magnification of 400× (left panel) and IHC scores were calculated (right panel). *P < 0.05