磷脂酰肌醇转运蛋白细胞质1在肝细胞癌中表达及临床意义

Expression of phosphatidylinositol transfer protein cytoplasmic 1 in hepatocellular carcinoma and its clinical significance

背景和目的:肝细胞癌(HCC)侵袭性强,极易发生复发转移,临床预后差。目前HCC发生发展分子机制仍然不清楚。磷脂酰肌醇转运蛋白细胞质1(PITPNC1)是一种脂质代谢相关基因,表现出促癌作用。然而,PITPNC1是否在HCC发展中发挥作用仍然未知。因此,本研究探讨PITPNC1在HCC中的表达及其作用。方法:招募2015年1月—2018年12月间中南大学湘雅医院行肝切除手术的HCC患者116例进行前瞻性队列研究,收集患者的病历资料和组织标本,并进行规律随访。通过免疫组化方法检测患者组织标本PITPNC1蛋白的表达,分析PITPNC1表达和临床病理特征预后之间的关系。通过LCCLD数据库分析PITPNC1在人HCC细胞系中的表达,利用慢病毒包装小RNA干扰PITPNC1在高侵袭转移性HCC细胞系MHCC97H中表达,利用集落形成和皮下成瘤实验观察PITPNC1表达与HCC生长的关系,并对皮下移植瘤行油红O染色。利用生物信息学方法分析PITPNC1作用的分子机制。结果:PITPNC1蛋白阳性染色定位于细胞浆,在癌组织阳性表达率为76.7%(88/116),在癌旁组织阳性表达率为21.5%(24/116),差异有统计学意义(P<0.001)。PITPNC1高表达与卫星结节(P=0.041)、血管侵犯(P<0.001)、肿瘤分化(P=0.027)、BCLC分期(P=0.009)、TNM分期(P=0.028)明显有关。Kaplan-Meier生存分析表明,PITPNC1高表达HCC患者总体生存(OS)率与无复发生存(RFS)率均明显降低(均P<0.001);PITPNC1表达是OS率与RFS率的独立影响因素(HR=11.775,95%CI=1.462~4.082,P=0.006;HR=1.928,95%CI=1.306~4.889,P=0.004)。PITPNC1沉默后,MHCC97H细胞体内和体外生长均明显抑制(均P<0.05)。油红O染色显示,PITPNC1表达下调后,皮下移植瘤的脂质积累明显减少(P<0.05)。数据库分析结果显示,PITPNC1过表达涉及脂质代谢相关的PPAR信号通路活性。结论:PITPNC1是HCC新的癌基因和不良预后标志物。PITPNC1可能通过调控脂质代谢途径而在促进HCC生长过程中可能起重要作用。

Background and Aims:Hepatocellular carcinoma(HCC)is characterized by high invasiveness,frequent recurrence,and poor clinical prognosis.The molecular mechanisms underlying the occurrence and development of HCC remain unclear.Phosphatidylinositol transfer protein cytoplasmic 1(PITPNC1)is a lipid metabolism-related gene shown to promote cancer.However,the role of PITPNC1 in the development of HCC remains unknown.Thus,this study aimed to investigate the expression and function of PITPNC1 in HCC.Methods:A prospective cohort study was conducted on 116 patients with HCC who underwent liver resection surgery at Xiangya Hospital,Central South University,from January 2015 to December 2018.Patient medical records and tissue specimens were collected,and regular follow-ups were performed.Immunohistochemistry was used to detect PITPNC1 protein expression in patient tissue samples,and the relations of PITPNC1 expression with clinicopathologic features and prognosis were analyzed.The expression of PITPNC1 in human HCC cell lines was analyzed using the LCCLD database.Lentivirusmediated small RNA interference was utilized to silence PITPNC1 expression in the highly invasive and metastatic HCC cell line MHCC97H.Colony formation and subcutaneous tumor experiments were performed to observe the relationship between PITPNC1 expression and HCC growth,and Oil Red O staining was conducted on the subcutaneous xenografts.Bioinformatics analysis was used to investigate the molecular mechanisms of PITPNC1 action.Results:The PITPNC1 protein was positively stained in the cytoplasm,with a positive expression rate of 76.7%(88/116)in tumor tissues and 21.5%(24/116)in adjacent non-tumor liver tissues,and the difference was statistically significant(P<0.001).High PITPNC1 expression was significantly associated with satellite nodules(P=0.041),vascular invasion(P<0.001),tumor differentiation(P=0.027),BCLC stage(P=0.009),and TNM stage(P=0.028).Kaplan-Meier survival analysis revealed that HCC patients with high PITPNC1 expression had significantly lower overall survival(OS)and recurrence-free survival(RFS)rates(both P<0.001);PITPNC1 expression was an independent factor influencing OS and RFS(HR=11.775,95%CI=1.462-4.082,P=0.006;HR=1.928,95%CI=1.306-4.889,P=0.004).After PITPNC1 silencing,both in vitro and in vivo growth of MHCC97H cells were significantly suppressed(both P<0.05).Oil Red O staining showed a significant reduction in lipid accumulation in the subcutaneous xenografts following PITPNC1 downregulation(P<0.05).Database analysis indicated that PITPNC1 overexpression was associated with lipid metabolism-related PPAR signaling pathway activity.Conclusion:PITPNC1 is a novel oncogene and adverse prognostic marker in HCC.It may play a significant role in promoting HCC growth by regulating the lipid metabolism pathway.