Loss of nuclear prothymosin-α expression is associated with disease progression in human superficial bladder cancer

Abstract

In this paper, we report a study on the clinical relevance of prothymosin-α expression and its correlation with intratumoral Foxp3(+) and CD8(+) lymphocytes (Foxp3(+)TIL and CD8(+)TIL) in bladder cancer patients. We used immunohistochemical staining for prothymosin-α, Foxp3, and CD8 on 101 tumor specimens harvested by endoscopic resection. The results were correlated with clinicopathological variables and clinical outcome in bladder cancer patients, particularly in 73 patients with superficial disease, using the log-rank test and Cox proportional hazard model. Overall, of the tumors, 30 % were negative, 34 % showed nuclear, and 37 % showed cytoplasmic prothymosin-α expression. Foxp3(+)TILs were detected in 11 % of patients (nonnuclear vs. nuclear, p = 0.096). Patients with a history of urothelial carcinoma have a higher frequency of nonnuclear prothymosin-α expression than those without (p = 0.016, chi-square test). By univariate and multivariate analyses of cases with superficial disease, grade and stage were identified as independent predictors for recurrence-free survival (p = 0.016 and 0.016, respectively). Higher stage and nonnuclear prothymosin-α expression independently predict shorter progression-free survival (p = 0.006 and 0.043, respectively). The presence of Foxp3(+)TILs was significantly associated with disease progression by univariate analysis (p = 0.022), but not by multivariate analysis (p = 0.147). In vitro assays showed that J82 cells which express ectopically nuclear prothymosin-α exhibit higher growth rate and secrete less TGF-β1 than those with cytoplasmic expression or control cells. Altogether, prothymosin-α expression is a determinant of disease progression in superficial bladder cancer. Foxp3(+)TILs tend to be found more often in bladder cancer with nonnuclear prothymosin-α expression. Future study is required to unravel their interaction.

Prothymosin‐α enhances phosphatase and tensin homolog expression and binds with tripartite motif‐containing protein 21 to regulate Kelch‐like ECH‐associated protein 1/nuclear factor erythroid 2‐related factor 2 signaling in human bladder cancer

“…In contrast, the latter two, detected in CD8 + T cells and cervicovaginal lavage, also exhibit anti‐HIV immunomodulatory activity despite the lack of NLS . Our previous study has shown WT PTMA expression can promote in vitro J82 cell proliferation than did ∆NLS PTMA or null expression, which is inconsistent with the in vivo J82 xenograft tumor growth shown in the current study. The probable reasons for this discrepancy can be obtained from the findings of the comparison of mRNA array using three J82 transfectants, demonstrating that the presence of NLS, in terms of PTMA protein, influences several signaling pathways, such as cell cycle regulation, PIP3‐Akt, GnRH, TGF‐β/smad, hepatic growth factor, estrogen receptor and IFN‐γ signaling.…”

“…To investigate whether localization of PTMA expression can influence tumor cell growth, J82 transfectants with either ectopic WT PTMA (wild‐type, or full‐length, nuclear pattern), ∆ NLS PTMA (deleted nuclear localization signal, cytoplasmic pattern) expression or control were generated by infecting J82 cells with lentiviruses carrying the full‐length PTMA gene, ∆ NLS PTMA gene or control, and then cell sorting. In addition to urea‐PAGE assay for WT PTMA or ∆ NLS PTMA protein expression shown in the previous study, all three transfectants were confirmed by immunohistochemical staining for subcellular localization of PTMA expression in the xenografts of SCID mice (Figure F‐H), as well as examining with qRT‐PCR for mRNA levels (Figure I), mimicking nuclear, cytoplasmic or null PTMA expression. Our previous study has shown that J82 cells with ectopic WT PTMA expression exhibit higher growth rate and secrete less transforming growth factor (TGF)‐β1 than do those with ∆ NLS PTMA expression or control cells, as well as less VEGF production in the current study (Figure J).…”

“…In addition to urea‐PAGE assay for WT PTMA or ∆ NLS PTMA protein expression shown in the previous study, all three transfectants were confirmed by immunohistochemical staining for subcellular localization of PTMA expression in the xenografts of SCID mice (Figure F‐H), as well as examining with qRT‐PCR for mRNA levels (Figure I), mimicking nuclear, cytoplasmic or null PTMA expression. Our previous study has shown that J82 cells with ectopic WT PTMA expression exhibit higher growth rate and secrete less transforming growth factor (TGF)‐β1 than do those with ∆ NLS PTMA expression or control cells, as well as less VEGF production in the current study (Figure J). In addition, ∆ NLS PTMA expression can promote J82 xenograft growth in SCID mice and shorten mice survival as compared with WT PTMA or null PTMA expression (Figure K,L).…”

“…Samples were analyzed blindly by one pathologist. Any tumor specimens exhibiting more than 25% immunoreactive tumor cells within one high‐power field were considered positive tumors as in our previous study …”

“…From our previous studies, we found that not only PTMA could be detected in the nucleus of the tumor cell, but also in the cytoplasm. The loss of nuclear PTMA (cytoplasmic or null expression pattern) predicts shorter progression‐free survival in superficial bladder cancer and UTUC . These findings prompted us to explore the molecular and regulatory mechanisms of PTMA expression involved in human urothelial carcinoma.…”