Down-regulation of NTSR3 inhibits growth, metastasis, and PI3K/AKT and MAPK signaling pathways in colorectal cancer cells.

Colorectal cancer is a common malignancy. NTS receptor 3 (NTSR3) plays an important part in multiple cancers. This study aimed to study the effect of NTSR3 on cell growth and metastasis of colorectal cancer. Western blot analysis, real-time PCR, immunofluorescence staining, MTT, cell cycle assay, cell apoptosis assay, Hoechst staining, caspase-3 and caspase-9 activity assay, cell adhesion assay, wound healing assay, and transwell assay were used in this study. We showed that NTSR3 was expressed at relatively high level in SW620 and SW480 cells of colorectal cancer. NTSR3 knockdown could suppress cell growth and promote cell apoptosis. Meanwhile, the expression levels of cyclinD1, cyclinE1, CDK4, and p-RB protein were decreased and the levels of p-P27, P15, P21, cleaved-caspase-3 and cleaved-caspase-9 protein were increased. Cell invasion and cell migration were decreased in NTSR3-silenced cells. In addition, the rescue experiments demonstrated that overexpression of siRNA resistant alleles of NTSR3 could abrogate the NTSR3 siRNA-mediated cell function. Further, down-regulation of NTSR3 inactivated PI3K/AKT and MAPK signaling pathways. Collectively, these data demonstrate that NTSR3 knockdown inhibits cell growth, metastasis, and PI3K/AKT and MAPK signaling pathway in colorectal cancer cells. Our study suggests that NTSR3 as a potential therapeutic target to treat colorectal cancer.