PGAM5在胰腺癌中的表达及其与临床病理指标的关系

Expression of PGAM5 and its association with clinicopathologic characteristics in pancreatic cancer

目的:探讨胰腺癌组织磷酸甘油酸变位酶5(PGAM5)的表达水平及其与胰腺癌患者临床病理指标的关系。方法:利用癌症基因组图谱(TCGA)和基因型组织表达(GTEx)的RNA-seq数据集,分析胰腺癌和正常组织中PGAM5 mRNA的表达差异。选取2018年01月—2020年12月于滁州市第一人民医院就诊的胰腺癌患者86例,另外收集6对新鲜胰腺癌组织及癌旁组织。采用Western blot检测6对新鲜胰腺癌组织匀浆中PGAM5蛋白的表达水平;免疫组织化学(IHC)检测PGAM5蛋白在86例胰腺癌组织中的表达水平,并分析其与患者临床病理指标之间的相关性。采用Cox回归模型进行单因素和多因素分析,采用Kaplan-Meier曲线进行生存分析。结果:生物信息学分析显示,在胰腺癌组织中,PGAM5 mRNA的表达水平高于正常组织,差异具有统计学意义(P<0.01)。Western blot检测显示PGAM5蛋白在新鲜胰腺癌组织中表达水平较癌旁组织中显著升高(P<0.01)。IHC染色显示PGAM5蛋白在胰腺癌组织中呈棕黄色颗粒状,主要在细胞胞浆中表达;IHC半定量分析发现,与对应的癌旁正常组织相比,PGAM5蛋白在胰腺癌组织中的表达水平显著升高(P<0.01)。PGAM5蛋白的表达水平与胰腺癌患者TNM分期(P=0.001)、肿瘤长径(P=0.006)和远处转移(P=0.004)相关,与年龄(P=0.772)、性别(P=0.911)和淋巴结转移(P=0.085)无明显相关。Spearman相关分析表明,PGAM5蛋白表达水平与TNM分期(r=0.428,P<0.01)、肿瘤长径(r=0.276,P=0.010)、淋巴结转移(r=0.238,P=0.027)和远处转移(r=0.304,P=0.004)相关,与年龄(r=0.013,P=0.902)和性别(r=0.042,P=0.699)无明显关系。单因素分析和多因素分析均提示,PGAM5[HR=2.125,95%CI(1.210,3.646),P=0.008]是胰腺癌患者生存预后的独立影响因素。Kaplan-Meier生存曲线显示,PGAM5蛋白高表达组的胰腺癌患者中位总生存期(OS)为17个月,PGAM5低表达组的中位OS为27个月,差异有统计学意义(P<0.01)。结论:PGAM5蛋白在胰腺癌组织中表达水平升高,并与胰腺癌患者恶性临床病理指标密切相关,PGAM5高表达提示预后不良;PGAM5可能是胰腺癌预后判断的潜在生物标志物。

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 Peoples 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).Spearmans 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.