High expression of glycolysis-related PGM2 gene in relation to poor prognosis and deficient immune cells infiltration in lung adenocarcinoma: a study based on bioinformatics analysis

BACKGROUND: Lung adenocarcinoma (LUAD) is the most important subtype of lung cancer and usually metastasizes. Patients with LUAD usually had a poor prognosis. Identifying viable molecular markers for diagnostic and prognostic prediction among individuals with LUAD is critical for the future management of this disease. This study aimed to determine and verify a correlation between the glycolysis-related phosphoglucomutase 2 (PGM2) gene and dissatisfactory results and deficient infiltration of immune cells in LUAD. METHODS: The expression of PGM2 in LUAD and adjoining normal tissues was screened from The Cancer Genome Atlas (TCGA) data and human protein atlas (HPA), and validatied by quantative reverse transcription polymerase chain reaction (qRT-PCR). We examined the correlation between PGM2 expression and clinicopathologic characteristics (including pathological stage, gender, M stage, smoker, age, N stage, race, and number pack years smoked) by multivariable approaches and Kaplan-Meier survival curves. The proteins network with PGM2 was built using the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database. The correlation between PGM2 expression and infiltration of immune cells, along with the corresponding gene marker sets, was investigated through the Gene Expression Profiling Interactive Analysis (GEPIA) and Tumor Immune Estimation Resource (TIMER) databases. We evaluated the possible correlation between PGM2 expression and progression-free interval (PFI), disease-specific survival (DSS), and overall survival (OS) in LUAD patients. RESULTS: Expression of PGM2 was up-regulated in LUAD tissues (P=0.003). According to the multivariate logistic regression analysis, the elevated expression level of PGM2 exhibited a remarkable correlation with advanced tumor-node-metastasis (TNM) stage, high-grade malignancy, and primary therapeutic outcome . Overexpression of PGM2 was shown to be correlated with an unfavorable prognosis including OS (P=0.004, HR =1.54), DSS (P=0.003, HR =1.77), and PFI (P=0.003, HR =1.5) in LUAD. The proteins PGM1 and UGP2 were shown to have a significant correlation with PGM2. Additionally, PGM2 was associated with the lack of infiltrating immune cells as well as their associated gene marker sets in LUAD. CONCLUSIONS: Overexpression of PGM2 was shown to be associated with the progression and an unfavorable prognosis of LUAD, as well as with inefficient immune cell infiltration. PGM2 was expected to be a potential biological marker for predicting the prognosis of patients with LUAD.