NUCKS1 promotes gastric cancer cell aggressiveness by upregulating IGF-1R and subsequently activating the PI3K/Akt/mTOR signaling pathway

Abstract The effects of nuclear ubiquitous casein and cyclin-dependent kinase substrate 1 (NUCKS1) on tumor cells and the relevant mechanisms are less well defined. This study aimed to explore the role and mechanism of action of NUCKS1 in gastric cancer (GC) progression. The expression dynamics of NUCKS1 were examined using microarray-based immunohistochemistry (IHC) in a group of carcinomatous and adjacent non-tumor specimens. Various in vitro and in vivo assays were performed to clarify the function of NUCKS1 in GC and its underlying mechanisms. In our research, NUCKS1 overexpression was identified by IHC in 86/200 (43%) GC patients, was significantly related to the invasive phenotype of GC and was an indisputable predictor of shortened survival. Depleting NUCKS1 in GC cells significantly induced apoptosis and reduced cell proliferation and invasiveness in vitro and inhibited tumor growth in vivo. Additionally, ectopic overexpression of NUCKS1 in GC cells enhanced proliferation and invasion in vitro and promoted tumor growth in vivo. Importantly, PI3K/Akt/mTOR signaling pathway activity was inhibited upon downregulation of NUCKS1 expression and enhanced by ectopic overexpression of NUCKS1. Subsequently, the insulin-like growth factor 1 receptor (IGF-1R) gene was found to be a potential downstream target of NUCKS1 in GC cells, and knockdown of IGF-1R eliminated the augmentation of GC cell migration, invasion and proliferation as well as PI3K/Akt/mTOR signaling pathway activity by ectopic NUCKS1. The data suggested that NUCKS1 enhanced GC aggressiveness via the PI3K/Akt/mTOR signaling pathway in an IGF-1R-dependent manner. NUCKS1 or its respective signaling pathways could hold immense promise as potent anticancer targets for GC treatment.