1. Department of Pathology, Chi Mei Medical Center, Liouying, Taiwan;
2. Institute of Biomedical Science National Sun Yat-sen University, Kaohsiung, Taiwan;
3. Department of Medical Laboratory Science and Biotechnology, Chung Hwa University of Medical Technology;
4. Department of Urology, Chi Mei Medical Center; Tainan, Taiwan;
5. Department of Urology, Faculty of Medicine, Kaohsiung Medical University;
6. Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung Medical University;
7. Department of Urology, Kaohsiung Municipal Ta-Tung Hospital;
8. Department of Pathology, Kaohsiung Medical University Hospital, Kaohsiung Medical University;
9. Department of Anesthesiology, Chi Mei Medical Center, Tainan, Taiwan;
10. Division of Clinical Pathology, Chi Mei Medical Center, Tainan, Taiwan;
11. National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan;
12. Department of Biotechnology, Southern Taiwan University of Science and Technology, Tainan, Taiwan;
13. Institute of Clinical Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
Background: The TP53 tumor suppressor gene plays a crucial role in the carcinogenesis of many malignancies, including urothelial carcinoma (UC). Overexpression of p53 is associated with poor prognosis in UC. Recently, RING finger protein 128 (RNF128) was shown to be involved in p53-induced apoptosis, forming a negative feedback loop. However, the significance of RNF128 in patients with UC remains unknown. In this study, our aim was to evaluate the expression of RNF128 in UC and to assess its predictive and prognostic value in a well-established cohort.
Methods: Through data mining from a published transcriptome (GSE31684), RNF128 was identified as the most differentially expressed gene in UC among those associated with negative regulation of the cytokine biosynthetic process (GO:0042036). Its immunoexpression was further evaluated using the H-scores of 340 patients with upper urinary tract UC (UTUC) and 295 with urinary bladder UC (UBUC). The scores were correlated with clinicopathological features, disease-specific survival (DSS) and metastasis-free survival (MeFS). We also used Western blot analysis to evaluate RNF128 protein expression in human urothelial cell (HUC) lines.
Results: Downregulation of RNF128 expression was significantly associated with advanced pT stage (p<0.001), high histological grade (UTUC, p<0.001; UBUC, p=0.035), nodal metastasis (UTUC, p<0.001; UBUC, p=0.001), vascular invasion (UTUC, p<0.001; UBUC, p=0.008) and high mitotic rate (UTUC, p=0.003; UBUC, p=0.023). Low expression of RNF128 was an adverse prognosticator for DSS (UTUC, p<0.0001; UBUC, p<0.0001) and MeFS (UTUC, p<0.0001; UBUC, p=0.0002). Moreover, low expression was predictive of poor DSS (UTUC, p=0.006; UBUC, p=0.003) and MeFS (UTUC, p=0.009; UBUC, p=0.036) in multivariate comparisons. Western blot analysis showed that the RNF128 protein was downregulated in invasive urothelial cancer cell lines.
Conclusion: Our findings showed that downregulation of RNF128 was correlated with cancer invasiveness and metastasis as well as reduced survival in patients with UTUC and UBUC, identifying RNF128 as a prognostic factor in UC.
Keywords: RNF128, Grail, urothelial carcinoma, prognosis.