Expression and clinical significance of geranylgeranyl diphosphate synthase1 (GGPS1) in lung squamous cell carcinoma

Abstract

Objective·To investigate the expression and clinical significance of geranylgeranyl diphosphate synthase1 (GGPS1) in lung squamous cell carcinoma (LUSC) by bioinformatics and immunohistochemistry.Methods·Firstly, the transcriptome data of LUSC tissues and paired normal tissues were downloaded from UCSC Xena platform. The data were standardized and differentially expressed by R language, and verified by UALCAN database. UALCAN and LinkedOmics databases were used to analyze the relationship between GGPS1 expression and clinicopathological features in LUSC patients. The Kaplan-Meier Plotter database was used to explore the effect of GGPS1 expression on prognosis in LUSC patients. The least absolute shrinkage and selection operator (LASSO) regression analyses were applied to screen gene correlation coefficients and risk scores. The diagnostic value of GGPS1 for LUSC was evaluated by nomogram and calibration curve. The protein-protein interaction (PPI) network of GGPS1 was constructed by using STRING and GeneMANIA databases. R language was used to select the differential genes related to GGPS1, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were performed. The expression of GGPS1 in LUSC patients was detected by immunohistochemistry, and its correlation with clinicopathological features and prognosis was analyzed.Results·Through the TIMER2.0 database, it was found that GGPS1 expression was increased in most tumors and was highly expressed in LUSC. The expression of GGPS1 in LUSC was higher than that in adjacent tissues in UCSC Xena and UALCAN databases (both P<0.05). It was found that the expression level of GGPS1 was higher in patients with late stage in UALCAN and LinkedOmics databases, and the overall survival (OS) of LUSC patients with high expression of GGPS1 was shorter (P<0.05) in the Kaplan-Meier Plotter database. Assessment of LUSC patients based on LASSO regression had good risk prediction efficacy. Constructing an individualised prediction model for LUSC patients has the best prediction accuracy. The results of GO and KEGG showed that GGPS1-related genes were mainly related to protein metabolism, regulation of lipid and cholesterol metabolism, nicotine addiction, phosphatidylinositol3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR), peroxisome proliferator-activated receptors (PPAR) signaling pathway and so on. The metabolic function of GGPS1 may promote tumorigenesis. The results of immunohistochemistry showed that GGPS1 was mainly located in the cytoplasm, and the expression of GGPS1 in LUSC tissues was higher than that in adjacent tissues (P<0.05). The high expression of GGPS1 was related to tumor size, lymph node metastasis and TNM stage of LUSC patients (all P<0.05), and the OS of patients with high expression of GGPS1 was significantly shorter than that of patients with low expression (P=0.000). Multivariate Cox regression analysis suggested that GGPS 1 could be used as an independent prognostic factor for LUSC.Conclusion·Compared with normal lung tissue, the expression of GGPS1 in LUSC is significantly increased, especially in patients with large tumor volume, positive lymph node metastasis and advanced stage. GGPS1 overexpression is an independent predictor of poor prognosis in LUSC patients. GGPS1 is expected to become a new molecular target for the diagnosis, treatment and prevention of LUSC.

Keywords

• geranylgeranyl diphosphate synthase 1 (ggps1)
• lung squamous cell carcinoma (lusc)
• bioinformatics
• immunohistochemistry
• clinical significance