Abstract: OBJECTIVE: To investigate expression levels of phosphoglycerate-mutase 5(PGAM5) in pancreatic cancer tissues and its associations with the clinicopathologic characteristics in the cancers among patients. METHODS: Differences of PGAM5 mRNA expression levels in pancreatic cancer and normal tissues were analyzed using RNA-seq datasets from The Cancer Genome Atlas(TCGA) and Genotype-Tissue Expression(GTEx). Eighty-six patients with pancreatic cancer who attended the First People's Hospital of Chuzhou from January 2018 to December 2020 were selected. Pathological specimens and clinical data of the patients were collected. Concentrations of the PGAM5 protein in the homogenates of 6 fresh pancreatic cancer tissues were detected by Western blot. Expression levels of PGAM5 in 86 pancreatic cancer tissues was detected by immunohistochemistry(IHC). Correlations between these expression levels and clinicopathologic characteristics were determined. Cox regression and Kaplan-Meier curves were used for survival analysis.RESULTS: Bioinformatics analysis showed that the expression levels of PGAM5 mRNA in pancreatic cancer tissues were significantly higher than that in normal tissues(P<0.001). Western blot assay showed that expression levels of the PGAM5 protein were elevated in fresh pancreatic cancer tissues. IHC staining showed that PGAM5 in the cancer tissues was in the form of brownish-yellow granules, and it was mainly expressed in the cytoplasm of cells. Semi-quantitative analysis revealed that the expression levels of PGAM5 were significantly elevated in the cancer tissues compared with paired paracancerous normal tissues(P<0.01). The expression levels of PGAM5 were correlated with TNM stage(P=0.001), tumor length(P=0.006), and distant metastasis(P=0.004) but not with age(P=0.772), gender(P=0.911), or lymph node metastasis(P=0.085).Spearman's correlation analysis showed that PGAM5 was associated with TNM stage(r=0.428, P<0.01), tumor length(r=0.276, P=0.010), lymph node metastasis(r=0.238, P=0.027), and distant metastasis(r=0.304, P=0.004) but not with age(r=0.013, P=0.902) or gender(r=0.042, P=0.699). Univariate analysis suggested that high PGAM5 expression increased the risk of death in pancreatic cancer patients, and the difference was statistically significant [HR=2.548, 95%CI=(1.556, 4.174), P<0.01]. Multifactorial analysis revealed that PGAM5[HR=2.125, 95%CI(1.210, 3.646), P=0.008], lymph node metastasis [HR=5.028, 95%CI(1.776, 14.240)], P=0.002 and distant metastasis [HR=8.866, 95%CI(4.470, 17.584), P<0.01] demonstrated independent influences on the survival prognosis of the patients. Kaplan-Meier survival curves showed that the median overall survival(OS) of the patients in the PGAM5 high expression group was 17 months, and that of the PGAM5 low expression group was 27 months, and the difference was statistically significant [HR=2.470, 95% CI(1.533, 3.980), P<0.01]. CONCLUSION: The expression levels of PGAM5 were elevated in pancreatic cancer tissues and were closely related to the malignant clinicopathologic features of the cancer patients, and the high expression of PGAM5 suggests poor prognosis. PGAM5 may be a potential biomarker for pancreatic cancer.

Key words: PGAM5, gastric cancer, clinicopathologic features, prognosis