The PI3K/Akt signaling pathway serves an essential role in various cellular processes, including cell growth, survival, cell motility, angiogenesis and cell metabolism. Loss of PTEN expression and hyperactivation of Akt can result in tumorigenesis. Previous studies observed expression of the Akt protein and absence of the PTEN protein in bladder cancer and non-small cell lung carcinoma tissues. The aim of the present study was to evaluate the expression status and prognostic value of PTEN and the PI3K/Akt signaling pathway in Taiwanese patients with upper tract urothelial carcinoma (UTUC). Archival formalin-fixed, paraffin-embedded (FFPE) tissues from 65 UTUC cases were stained via immunohistochemistry for PTEN, phosphorylated (p)Akt serine (Ser) 473 and pAkt threonine (Thr) 308 . The expression levels of each protein were significantly correlated with clinicopathological parameters. PTEN, pAkt Ser473 and pAkt Thr308 protein expression levels were higher in adjacent normal tissues compared with those in tumor tissues. Cytoplasmic PTEN protein expression levels were lower in high-stage tumors compared with those in low-stage tumors, and nuclear and cytoplasmic pAkt Thr308 protein expression levels were higher in high-grade tumors compared with those in low-grade tumors. Univariate analysis showed that high pathological tumor stage (pT2-4) [P=0.01; hazard ratio (HR)=3.40; 95% confidence interval (CI), 1.34–8.60], metastatic status (P=0.003; HR=3.55, 95% CI, 1.55–8.11), low cytoplasmic PTEN protein expression levels (P=0.016; HR=3.14; 95% CI, 1.24–7.95) and high cytoplasmic pAkt Ser473 protein expression levels (P=0.019, HR=2.71, 95% CI, 1.18–6.21) were predictive of poor overall survival. However, only metastatic status (P=0.031; HR=2.73; 95% CI, 1.10–6.78), low cytoplasmic PTEN protein expression levels (P=0.017; HR=3.29; 95% CI, 1.24–8.73) and high cytoplasmic pAkt Ser473 protein expression levels (P=0.027; HR=2.64; 95% CI, 1.12–6.23) remained significant in the multivariate analysis. Kaplan-Meier survival analysis showed that high T stage, metastasis, low expression levels of cytoplasmic PTEN protein and high expression levels of cytoplasmic pAkt Ser473 protein were significantly associated with poor survival (P=0.006, 0.001, 0.011 and 0.014, respectively). Co-expression of PTEN low /pAkt Ser473/high and pAkt Thr308/high phenotypes was associated with a less favorable overall survival (P=0.001). Overall, the present findings demonstrated that low expression levels of PTEN and high expression levels of pAkt Ser473 and pAkt Thr308 were predictors for poor overall survival in patients with UTUC.
Upper tract urothelial carcinoma (UTUC) is a rare malignancy accounts for about 5% of all urothelial tumours. The cancer cells start in the layer of tissue urothelium, and found in the renal pelvis, renal calyces or ureters. When compare the UTUC to the bladder urothelial carcinoma, the pathological and clinical findings are often look and act alike. Previous studies indicated that deletion of phosphatase and tensin homologue (PTEN) gene is common to be found in bladder cancer. As known tumor suppressor gene PTEN is located on chromosome ten and considered as an important negative regulator for the PIP3/Akt signaling pathway to promote cell proliferation and inhibit apoptosis. Thus, this study we aimed to determine clinical significance of PTEN in UTUC. We collected sixty-eight formalin-fixed paraffin-embedded (FFPE) UTUC samples, the tumor stage was according to American Joint Committee on Cancer (AJCC) with Ta (n=15), T1 (n=11), T2 (n=10), T3 (n=18), T4 (n=7) and seven patients with unknown; in which male no.32, female no.36; the median age is 68 y/o (range 40-85 y/o). Fluorescence in situ hybridization (FISH) was performed to exam the PTEN gene copy number or gene structure alterations of UTUC; besides, immunohistochemistry (IHC) analysis were used to observe the PTEN protein expression in the tumor. Our results showed PTEN mutations were observed in twenty-two tumors with heterozygous PTEN deletion; one tumor with homozygous PTEN deletion, and three tumors with PTEN monosomy. Further, heterozygous PTEN deletion was shown significantly associated with stage of pTa, pT1 and pT2 (P=0.048) and history of smoking (P=0.030). The IHC results showed lower expression level was common to be observed in the tumor area. Our findings suggest loss of PTEN is associated with the low-risk group of UTUC but not the high-risk group, the unknown mechanisms between these two subtypes might be existed. Besides, smoking could also as a factor highly emerge from genetic alterations in UTUC. In conclusion, PTEN genomic loss might act a predictive indicator of classification of UTUC, however, the clinical treatment could be different due to the underlying diversity of the molecular activities. Citation Format: Liang-Chen Li, Cheng-Keng Chuang, Hung-Ying Chiang, Ying-Tzu Chen, Po-Hung Lin, Kai-Jie Yu, See-Tong Pang, Wen Hui Weng*. Clinical significance of PTEN in UTUC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2727. doi:10.1158/1538-7445.AM2017-2727
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