Expression of Phospho-ELK1 and Its Prognostic Significance in Urothelial Carcinoma of the Upper Urinary Tract

Evaluation of molecular signatures in the urinary bladder and upper tract urothelial carcinomas: a prospective controlled clinical study

Background

Urothelial carcinomas (UC) can be either in the upper or in the lower urinary tract or both. Urothelial bladder cancer (UBC) is more common than upper tract urothelial carcinoma (UTUC). This research was designed to study the difference between UBC and UTUC using the molecular pathways including (MAPK/ERK) pathway, cell cycle regulating genes, and oncogenic genes.

Methods

To study the discrepancy between UBC and UTUC, a prospective trial was carried out for 31 radical cystectomy and 19 nephrouretrectomy fresh-frozen specimens of UBC and UTUC patients, respectively. The expression level of mRNA of eight genes namely EGFR, ELK1, c-fos, survivin, TP53, RB1, FGFR3, and hTERT was assessed in normal adjacent tissues, UTUC, and UBC by RT-PCR.

Results

Comparison between UTUC and UBC regarding the expression level of mRNA of the EGFR, ELK1, c-fos, survivin, TP53, and FGFR3 had significant difference (p-value < 0.001), while the expression level of RB1 and hTERT level had no significance. Sensitivity/specificity of EGFR, Elk1, c-fos, survivin, TP53, and FGFR3 was 0.78/0.90, 0.84/0.90, 0.84/0.80, 0.84/0.96, 0.94/0.93, and 0.89/0.93, respectively, to differentiate between UTUC and UBC.

Conclusions

Despite the fact that UTUC and UBC share the same origin, there is a clear evidence that there is a molecular difference between them. This molecular difference could be the reason that UTUC is more aggressive than UBC.

ELK1 Enhances Pancreatic Cancer Progression Via LGMN and Correlates with Poor Prognosis

Pancreatic cancer is one of the most lethal cancers and its prognosis is extremely poor. Clarification of molecular mechanisms and identification of prognostic biomarkers are urgently needed. Though we previously found that LGMN was involved in pancreatic carcinoma progression, the upstream regulation of LGMN remains unknown. We used reliable software to search for the potential transcription factors that may be related with LGMN transcription, we found that ELK1 could be a new regulator of LGMN transcription that binded directly to the LGMN promoter. Moreover, knocking down of ELK1 reduced pancreatic cancer cells proliferation, invasion and survival, while LGMN restored the malignancy of pancreatic cancer in vitro and in vivo. Overexpression of ELK1 further increased cancer cells proliferation, invasion and survival. Clinically, ELK1 and LGMN were positively correlated with clinical stage, degree of differentiation and Lymph node infiltration. ELK1 and LGMN were identified as independent prognostic factors for overall survival. The patients with low expression of ELK1/LGMN survived an average of 29.65 months, whereas those with high expression of ELK1/LGMN survived an average of 16.67 months. In conclusive, our results revealed a new mechanism by which ELK1 promoted the progression of pancreatic cancer via LGMN and conferred poor prognosis.

c-KIT-ERK1/2 signaling activated ELK1 and upregulated carcinoembryonic antigen expression to promote colorectal cancer progression

Carcinoembryonic antigen (CEA) is highly expressed in embryo and colorectal cancer (CRC) and has been widely used as a marker for CRC. Emerging evidence has demonstrated that elevated CEA levels promote CRC progression. However, the mechanism of the increased CEA expression in patients with primary and recurrent CRC is still an open question. In this study, we showed that c‐KIT, ELK1, and CEA were hyperexpressed in patients with CRC, especially patients with recurrent disease. From bioinformatics analysis, we picked ELK1 as a candidate transcription factor (TF) for CEA; the binding site of ELK1 within the CEA promoter was confirmed by chromatin immunoprecipitation and dual luciferase reporter assays. Overexpression of ELK1 increased CEA expression in vitro, while knockdown of ELK1 decreased CEA. Upregulated ELK1 promoted the adhesion, migration, and invasion of CRC cells, however knockdown of CEA blocked the activities of ELK1‐overexpressed CRC cells. Furthermore, we explored the role of c‐KIT‐ERK1/2 signaling in activation of ELK1. Blocking c‐KIT signaling using Imatinib or ISCK03 reduced p‐ELK1 expression and consequently decreased CEA levels in CRC cells, as did blocking the ERK1/2 pathway by U0126. Compared with wild type littermates, the c‐kit loss‐of‐functional Wads^m/m mice showed lowered c‐KIT, ELK1, and CEA expression. In conclusion, our study revealed that ELK1, which was activated by c‐KIT‐ERK1/2 signaling, was a key TF for CEA expression. Blocking ELK1 or its upstream signaling could be an alternative way to decelerate CRC progression. Besides being a biomarker for CRC, CEA could be used for guiding targeted therapy.

The Role of Steroid Hormone Receptors in Urothelial Tumorigenesis

Preclinical and/or clinical evidence has indicated a potential role of steroid hormone-mediated signaling pathways in the development of various neoplastic diseases, while precise mechanisms for the functions of specific receptors remain poorly understood. Specifically, in urothelial cancer where sex-related differences particularly in its incidence are noted, activation of sex hormone receptors, such as androgen receptor and estrogen receptor-β, has been associated with the induction of tumor development. More recently, glucocorticoid receptor has been implied to function as a suppressor of urothelial tumorigenesis. This article summarizes and discusses available data suggesting that steroid hormone receptors, including androgen receptor, estrogen receptor-α, estrogen receptor-β, glucocorticoid receptor, progesterone receptor and vitamin D receptor, as well as their related signals, contribute to modulating urothelial tumorigenesis.

Sex Hormone Receptor Signals in Human Malignancies

Sex steroids, including androgens, estrogens, and progestogens, are known to have widespread physiological actions beyond the reproductive system via binding to the sex hormone receptors, members of the nuclear receptor superfamily that function as ligand-inducible transcription factors [...].

ELK1 promotes urothelial tumorigenesis in the presence of an activated androgen receptor

We have recently demonstrated that ELK1, a transcription factor that triggers downstream targets including c-Fos proto-oncogene, promotes the growth of bladder cancer cells possessing a functional androgen receptor (AR). We here assessed the function of ELK1, as well as the efficacy of a selective α1A-adrenergic blocker silodosin that has been shown to inhibit ELK1 activity in bladder cancer cells, in urothelial tumorigenesis. The level of ELK1 expression in an immortalized normal urothelial cell line SVHUC stably expressing wild-type AR (SVHUC-AR) was considerably higher than that in AR-negative SVHUC-vector cells, which was induced further or reduced by dihydrotestosterone or silodosin treatment, respectively. In SVHUC-AR cells exposed to a chemical carcinogen 3-methylcholanthrene, silodosin significantly reduced the expression levels of oncogenes (e.g. c-Fos, Jun, Myc), as well as phospho-p38 MAPK and phospho-ERK proteins, and increased those of tumor suppressor genes (e.g. p53, PTEN, UGT1A). ELK1 suppression via ELK1-short hairpin RNA virus infection or silodosin treatment also resulted in significant inhibition in 3-methylcholanthrene-induced neoplastic transformation of SVHUC-AR cells, but not that of SVHUC-vector cells. In N-butyl-N-(4-hydroxybutyl)nitrosamine-treated male C57BL/6 mice, the incidence rate of bladder tumors was significantly (P = 0.007) lower in the silodosin group than in the control group. ELK1 thus appears to play a critical role in urothelial tumorigenesis, and silodosin prevents it presumably via down-regulation of ELK1. Moreover, ELK1 may require an activated AR for inducing neoplastic transformation of urothelial cells. Our findings may therefore offer a novel chemopreventive approach, via ELK1 inactivation using silodosin treatment, for bladder cancer.

Forkhead box O1 as an indicator of prognosis is inactivated in urothelial carcinoma of the upper urinary tract

The transcription factor forkhead box O1 (FOXO1) can be inactivated via its phosphorylation, resulting in suppression of apoptosis. Using immunohistochemistry, the expression of a phosphorylated form of FOXO1 was assessed in upper urinary tract urothelial carcinoma (UUTUC) specimens. Overall, phospho-FOXO1 (p-FOXO1) was immunoreactive in all 99 UUTUC specimens [12 (12.1%) weak (1+), 46 (46.5%) moderate (2+) and 41 (41.4%) strong (3+)], which was significantly (P=0.018) increased, compared with benign urothelium specimens [77/82 (93.9%): 18 (22.0%) 1+, 41 (50.0%) 2+ and 18 (22.0%) 3+]. Muscle invasion (P=0.031) and lymphovascular invasion (P=0.025) were observed more frequently in p-FOXO1(2+/3+) tumor samples compared with p-FOXO1(1+) tumor samples. No statistically significant associations between p-FOXO1 expression and tumor grade or presence of concurrent carcinoma in situ, hydronephrosis or lymph node metastasis were observed. Furthermore, the levels of p-FOXO1 and estrogen receptor-β expression were significantly (P<0.05) correlated in UUTUC samples [correlation coefficient (CC)=0.244], particularly in tumor samples from male patients (CC=0.330). Additionally, patients with p-FOXO1(3+) tumors had a significantly increased risk of cancer-specific mortality (P=0.043), compared with those with p-FOXO1(1+/2+) tumors. Multivariate analysis further demonstrated a notable, albeit not significant, association between p-FOXO1 expression and cancer-specific survival (hazard ratio=2.204; P=0.053). These findings indicate that FOXO1 is inactivated in UUTUC specimens and p-FOXO1 overexpression may serve as a predictor of poor patient outcomes.