Expression Level of Small Nuclear Ribonucleoprotein D1 in Gastric Cancer and Its Effect on Prognosis.

Abstract

Objective To investigate the expression of small nuclear ribonucleoprotein D1 (SNRPD1) in the gastric cancer tissue and evaluate the predictive value of SNRPD1 expression level for the long-term prognosis of gastric cancer patients and the possible functioning mechanism of SNRPD1. Methods The UALCAN and Gene Expression Profiling Interactive Analysis (GEPIA) were employed to analyze the expression level of SNRPD1 in pan-cancer and its relationship with the prognosis of gastric cancer.The clinical data of 109 patients who underwent radical surgery for gastric cancer from January 2014 to January 2017 in the First Affiliated Hospital of Bengbu Medical University were retrospectively analyzed.Gastric cancer and paracancerous tissue samples were collected,and the expression of SNRPD1 was detected by immunohistochemical staining.Lentiviral transfection was employed to construct the BGC-823 gastric cancer cell models with stable high and low expression of SNRPD1,respectively.The CCK-8 assay and colony formation assay were employed to measure the proliferation of gastric cancer cells,and flow cytometry was used to analyze the cell cycle.Western blotting was employed to determine the expression levels of proteins in the signaling pathway. Results The data from UALCAN and GEPIA showed that SNRPD1 was highly expressed in the tissue of malignant tumors including gastric cancer (P<0.001).The expression level of SNRPD1 in the gastric cancer tissue was higher than that in the paracancerous tissue (P<0.001).Moreover,the expression level of SNRPD1 was positively correlated with the levels of carcinoembryonic antigen (P<0.001),carbohydrate antigen 19-9 (P<0.001),G stage (P=0.042),T stage (P=0.002),and N stage (P=0.027) in the patients with gastric cancer.The high expression of SNRPD1 had a predictive value for the long-term prognosis of gastric cancer (P<0.001),and it was an independent risk factor for the death of gastric cancer patients (P=0.003).The results of gene ontology and kyoto encyclopedia of genes and Genomes enrichment analyses showed that SNRPD1 was involved in the regulation of the cell cycle.The results of CCK-8 and colony formation assays showed that up-regulation of SNRPD1 promoted the proliferation of gastric cancer cells (P<0.001,P<0.001).The up-regulation of SNRPD1 up-regulated the expression of cyclin-dependent kinase 6 and G₁/S-specific cyclin-D1 (P<0.001,P=0.002),whereas the interference in SNRPD1 led to opposite results (P=0.004,P<0.001).SNRPD1 accelerated the G₁/S phase transition of gastric cancer cells (P<0.001).The overexpression of SNRPD1 promoted the expression of phosphorylated phosphatidylinositol 3-kinase (PI3K) and phosphorylated protein kinase B (Akt) in gastric cancer cells (P=0.043,P<0.001),whereas disruption of SNRPD1 inhibited their expression (both P<0.001).Insulin-like growth factor 1,an agonist of the PI3K/Akt signaling pathway,promoted the proliferation of gastric cancer cells with SNRPD1 disturbed (P=0.002). Conclusion High expression of SNRPD1 in the gastric cancer tissues is associated with poor prognosis,and it may promote tumor cell proliferation and regulate the cell cycle by activating the PI3K/Akt signaling pathway.