Endothelin-1: a predictor of extracapsular extension in clinically localized prostate cancer?

Early mRNA Expression of Neuroendocrine Differentiation Signals Predicts Recurrence After Radical Prostatectomy: A Transcriptomic Analysis

Background

Neuroendocrine differentiation (NED) of prostate cancer (PC) is a process that often occurs under evolutionary pressure from pharmacologic blockade of androgen receptor signaling at advanced stages of the disease. Identifying a subset of early PC that has a higher likelihood to evolve into this entity is key for developing therapeutic strategies that could more effectively target this phenotype. This study aimed to assess the prognostic relevance of mRNA expression of major players involved in NED of primary prostate tumors.

Methods

RNA sequencing data from 122 patients with localized PC were analyzed. Transcript levels of key genes involved in NED, with a focus on endothelin axis and nuclear factor kappa B (NF-κB), were assessed and were correlated with time to prostate specific antigen (PSA) recurrence. Copy number alteration of tumor suppressor genes and gene expression of additional signals hallmarking NED was compared between altered and unaltered groups, including lineage determining transcription factors, transcriptional repressors, cell cycle and epigenetic regulators.

Results

The presence of altered mRNA expression using a z-score threshold of 2 in NFKB1, RELA, EDN1, EDNRA, and EDNRB genes was associated with a higher Gleason score (P < 0.001) and a shorter time to biochemical recurrence (BCR) (P = 0.029). There was a significant direct correlation between NFKB1 and RELA (P < 0.001), NFKB1 and EDNRA (P < 0.001), NFKB1 and EDNRB (P < 0.001), EDNRA and EDNRB expression (P < 0.001). ASCL1 (q < 0.001), ONECUT2 (q < 0.001), DLL3 (q = 0.019), AURKA (q = 0.013), AURKB (q = 0.014), PLK1 (q < 0.001), and EZH2 (q < 0.001) were enriched in patients with tumors harboring alterations in endothelin axis and NF-κB subunit genes whereas REST was downregulated (q < 0.001).

Conclusions

This analysis suggests that altered mRNA expression of NF-κB and endothelin axis genes in early PC is not only a harbinger of a more aggressive clinical course but is also associated with aberrant gene expression of several transcription factors, transcriptional repressors, cell cycle and epigenetic regulators that are directly involved in NED, in line with their biological roles. This may have implications for closer follow-up and potential use of targeted therapeutic approaches postoperatively in the adjuvant setting to improve outcomes of these patients.

The role of the endothelin axis in promoting epithelial to mesenchymal transition and lymph node metastasis in prostate adenocarcinoma

Introduction:

Aberrant activation of endothelin (ET) axis has been identified as a key player in tumor growth and metastasis in several tumor types. However, little is known about the possible interaction of the ET with epithelial to mesenchymal transition (EMT), a process that transforms tumor cells in a motile, resistant to apoptosis phenotype prone to invasion and metastasis. The aim of this study was to investigate the activation of the ET axis in prostate adenocarcinoma and examine possible associations with EMT markers, lymph node (LN) metastasis, and other clinicopathological parameters.

Materials and Methods:

We immunohistochemically evaluated the expression of ET-1 and its receptors A and B (ET-A, ET-B) in 64 N0 and 23 N1 prostate adenocarcinoma cases. EMT markers E-cadherin, N-cadherin, and β-catenin and the transcriptional factor SNAIL were evaluated. We examined possible correlations of ET pathway members with EMT markers, LN status, Gleason grade, and T stage.

Results:

Our results revealed increased expression of ET-1 and ET-A (but not ET-B) in prostate carcinoma; both ET-1 and ET-A were associated with lymph metastasis and T stage but not with Gleason grade. We observed E-cadherin and β-catenin decrease/relocalization and increased N-cadherin expression. SNAIL also showed increased expression in tumor tissue and was associated with LN metastasis (Mann–Whitney test, P = 0.0032). Expression of ET-1 and ET-A correlated well with SNAIL expression (Spearman r, P = 0.0002 and P = 0.0176, respectively).

Conclusions:

These findings indicate that activation of the ET pathway may induce EMT through SNAIL activation and correlates with increased metastatic potential.