PIK3C3与SMAD4在胰腺癌中的表达及作用

背景与目的 III型磷脂酰肌醇3-激酶（PIK3C3）及SMAD家族成员4（SMAD4）参与的信号通路与胰腺癌（PAAD）关系密切，但两者与PAAD发生及预后是否有关尚不十分清楚。本研究初步探究两者在PAAD中的表达及其对患者预后的影响。方法 利用UALCAN在线网站分析PIK3C3 mRNA和SMAD4 mRNA在PAAD中的表达及两者各自对PAAD患者预后的影响；从TCGA数据库下载PAAD患者PIK3C3 mRNA和SMAD4 mRNA的表达数据和相应临床病理资料，基于PIK3C3和SMAD4联合的mRNA表达水平，用一致性聚类分析将PAAD患者分为两个聚类，用Kolmogorov-Smirnov检验及Kaplan-Meier法分析两个聚类患者PIK3C3与SMAD4的mRNA表达模式、临床病理因素和总体生存率的差异；用免疫组化的方法检测PAAD和癌旁组织组织芯片中PIK3C3及SMAD4蛋白表达水平，并用独立样本t检验及ROC曲线下面积（AUC）评估两个蛋白在癌和癌旁组织中的差异；采用Kaplan-Meier的方法分析PIK3C3和SMAD4的蛋白水平单独及联合对PAAD患者生存的影响。结果 分析结果表明，PIK3C3 mRNA或SMAD4 mRNA水平在PAAD中均无明显变化，并且两者单独均不影响PAAD患者的预后（均P>0.05）。PAAD中与PIK3C3 mRNA与SMAD4 mRNA具有较高的共表达相关性。两个聚类的PAAD患者之间，两基因的mRNA水平及年龄有明显差异（均P<0.05），其中，PIK3C3 mRNA及SMAD4 mRNA均高表达聚类的PAAD患者预后较好（P=0.006）。PAAD组织中PIK3C3和SMAD4的蛋白表达水平均明显低于癌旁组织（均P<0.001），AUC分别为0.7417及0.7991。PIK3C3和SMAD4蛋白之一阳性患者比两蛋白均阴性的患者预后更好（P=0.0359）。结论 PIK3C3和SMAD4蛋白可作为PAAD潜在的诊断标志物，PIK3C3和SMAD4联合分析可成为PAAD患者预后评估的新指标。

Expressions and roles of PIK3C3 and SMAD4 in pancreatic adenocarcinoma

Background and Aims The signaling pathways associated with phosphatidylinositol 3-kinase catalytic subunit type 3 (PIK3C3) and SMAD family member 4 (SMAD4) are closely linked to pancreatic adenocarcinoma (PAAD). However, the relationships of the two genes with the occurrence or prognosis of PAAD are not fully understood. This study was conducted to investigate the expressions PIK3C3 and SMAD in PAAD and their influences on prognosis of patients.Methods The mRNA expressions of PIK3C3 and SMAD4 in PAAD tissue and their corresponding effects on prognosis of PAAD patients were analyzed using UALCAN website. The mRNA expression profiles of PIK3C3 and SMAD4 together with the indicated clinicopathologic data were downloaded from TCGA. The PAAD patients were divided into two clusters based on the combined expression of the PIK3C3 and SMAD4 genes by consensus clustering analysis, the differences in PIK3C3 mRNA or SMAD4 mRNA expression pattern, clinicopathologic variables and overall survival between two clusters were analyzed by Kolmogorov-Smirnov test and Kaplan-Meier method. The protein levels of PIK3C3 and SMAD4 in tissue microarrays containing PAAD and adjacent normal tissue samples were determined by immunohistochemical staining, and the differences of the two proteins in tumor and adjacent normal tissue were evaluated by independent sample t test as well as the area under ROC curve (AUC); the effects of individual PIK3C3 and SMAD4 protein or their combination on the survival of PADD patients were assessed by Kaplan-Meier analysis.Results The results of analysis showed that mRNA expression of PIK3C3 or SMAD4 alone did not change significantly in PAAD and did not significantly affect the prognosis of PAAD patients as well (all P>0.05). There was a high correlation in co-expression between PIK3C3 mRNA and SMAD4 mRNA in PAAD. Between the two clusters of PAAD patients, there were significant differences in mRNA levels of the two genes and age (P<0.05), and the cluster with higher mRNA level of both PIK3C3 and SMAD4 had a better survival probability (P=0.006). The protein levels of both PIK3C3 and SMAD4 were significantly higher in PAAD tissue than those in adjacent normal tissue (both P<0.001), and their AUC were 0.7417 and 0.7991, respectively. PAAD patients with positive expression of PIK3C3 or SMAD4 protein have better survival than those with negative expression of both proteins (P=0.0359).Conclusion This study suggests that PIK3C3 and SMAD4 protein may be the potential biomarkers for diagnosis of PAAD. Combined analysis of PIK3C3 and SMAD4 can be used for predicting the prognosis of PAAD patients.