人蛋白酶体β亚基4型在肝细胞癌中的表达及与预后的关系

目的 探讨人蛋白酶体β亚基4型(PSMB4)在肝细胞癌(以下简称肝癌)组织及正常肝组织中的表达及其在临床预后中的意义。方法 收集2017年1月-10月在南通大学附属医院行手术治疗的8例肝癌组织及癌旁组织标本,应用Western Blot法检测肝癌组织及相应癌旁组织中PSMB4蛋白的表达情况。另收集2009年1月-2012年10月南通大学附属医院留存的105例肝癌组织和25例正常肝组织的石蜡包埋标本,应用免疫组化法进一步检测PSMB4的表达情况。根据PSMB4免疫组化结果差异将105例肝癌患者分为PSMB4高表达组(n=57)和PSMB4低表达组(n=48)。计量资料2组间比较采用独立样本t检验;计数资料2组间比较采用χ2检验。Cox风险回归模型分析2组患者临床病理特征及预后的关系,Kaplan-Meier生存曲线分析不同PSMB4水平患者的生存情况。结果 2组间HBV感染、肿瘤最大直径、肿瘤分化程度、TNM分期比较差异均有统计学意义(χ^2值分别为22.482、8.219、14.964、6.587,P值均<0.05)。105例肝癌患者中57例(54.29%)为PSMB4 高表达,48例(45.71%)为PSMB4低表达;而25例正常肝组织中8例(32%)为PSMB4高表达,17例(68%)为PSMB4低表达或不表达,2组表达情况比较差异有统计学意义(χ^2=4.011, P<0.05)。PSMB4染色主要分布于细胞浆和细胞核内,染色呈棕色及棕黄色颗粒样。8例新鲜肝癌及癌旁组织样本中有7例肝癌组织的PSMB4蛋白表达水平明显高于癌旁组织(P值均<0.05)。单因素分析显示患者的5年生存状态与肿瘤大小(P=0.01)、转移情况(P<0.001)、分化程度(P=0.01)、TNM分期(P=0.003)以及PSMB4表达水平(P<0.001)有关;多因素结果显示肿瘤转移风险比(HR)=11.375,95%可信区间(95%CI):4.911~26.348)]和PSMB4高表达(HR=6.834,95%CI: 2.939~15.889)是肝癌患者的独立危险因素(P值均<0.001)。PSMB4高表达组患者5年生存率明显低于PSMB4低表达组(27.6% vs 79.2%, χ^2=22.96,P<0.05)。结论 PSMB4在肝癌组织中的表达增高,并且其高表达是肝癌患者预后的独立危险因素,PSMB4有可能作为肝癌预后的潜在标志及治疗的潜在靶点。

Expression of proteasome subunit beta type 4 in hepatocellular carcinoma and its association with prognosis

Objective To investigate the expression of proteasome subunit beta type 4 (PSMB4) in hepatocellular carcinoma (HCC) tissue and normal liver tissue and its significance in clinical prognosis. Methods Eight fresh HCC tissue specimens were collected from the patients who underwent surgical treatment in Affiliated Hospital of Nantong University from January to October, 2017, and Western Blot was used to measure the protein expression of PSMB4 in HCC tissue and the corresponding adjacent tissue. A total of 105 paraffin-embedded HCC tissue specimens and 25 paraffin-embedded normal liver tissue specimens, which were preserved in Affiliated Hospital of Nantong University from January 2009 and October 2012, were collected, and immunohistochemistry was used to measure the expression of PSMB4. According to the expression of PSMB4, 105 HCC patients were divided into high PSMB4 expression group with 57 patients and low PSMB4 expression group with 48 patients. The independent samples t-test was used for comparison of continuous data between groups, and the chi-square test was used for comparison of categorical data between groups. The Cox proportional-hazards regression model and the Kaplan-Meier survival curves were used to analyze the clinicopathological features and prognosis of the patients in the two groups. Results There were significant differences between the two groups in hepatitis B virus infection, maximum tumor diameter, degree of tumor differentiation, and TNM stage (χ2=22.482, 8.219, 14.964, and 6.587, all P<0.05). Among the 105 HCC patients, 57 (54.29%) had high PSMB4 expression and 48 (45.71%) had low PSMB4 expression, while among the 25 normal liver tissue specimens, 8 (32%) had high PSMB4 expression and 17 (68%) had low PSMB4 expression or no PSMB4 expression, and there was a significant difference in PSMB4 expression between the two groups (χ2=4.011, P<0.05). PSMB4 staining was mainly distributed in the cytoplasm and nucleus, with an appearance of brown or brownish yellow particles. Among the 8 fresh HCC tissue specimens, 7 specimens had significantly higher protein expression of PSMB4 than the corresponding adjacent tissue specimens (all P<0.05). The patients’ 5-year survival was associated with tumor size (P=0.01), metastasis (P<0.001), degree of tumor differentiation (P=0.01), TNM stage (P=0,003), and PSMB4 expression (P<0.001), among which metastasis (hazard ratio HR]=11.375, 95%confidence intervalCI]: 4.911-26.348, P<0.001) and high PSMB4 expression (HR=6.834, 95%CI: 2.939-15.889, P<0.001) were independent risk factors in HCC patients. The high PSMB4 expression group had a significantly lower 5-year survival rate than the low PSMB4 expression group (27.6% vs 79.2%, χ^2=22.96, P<0.05). Conclusion There is an increase in the expression of PSMB4 in HCC tissue, and high expression of PSMB4 is an independent risk factor for poor prognosis in HCC patients, suggesting that PSMB4 may serve as a potential prognostic marker or a potential target for treatment.