Prognostic effect of neuroendocrine differentiation in prostate cancer: A critical review

Remarks on Selected Morphological Aspects of Cancer Neuroscience: A Microscopic Photo Review

BACKGROUND

This short review and pictorial essay presents a morphological insight into cancer neuroscience, which is a complex and dynamic area of the pathobiology of tumors.

METHODS

We discuss the different methods and issues connected with structural research on tumor innervation, interactions between neoplastic cells and the nervous system, and dysregulated neural influence on cancer phenotypes.

RESULTS

Perineural invasion (PNI), the most-visible cancer-nerve relation, is briefly presented, focusing on its pathophysiology and structural diversity as well as its clinical significance. The morphological approach to cancer neurobiology further includes the analysis of neural density/axonogenesis, neural network topographic distribution, and composition of fiber types and size. Next, the diverse range of neurotransmitters and neuropeptides and the neuroendocrine differentiation of cancer cells are reviewed. Another morphological area of cancer neuroscience is spatial or quantitative neural-related marker expression analysis through different detection, description, and visualization methods, also on experimental animal or cellular models.

CONCLUSIONS

Morphological studies with systematic methodologies provide a necessary insight into the structure and function of the multifaceted tumor neural microenvironment and in context of possible new therapeutic neural-based oncological solutions.

MALAT1 promotes FOXA1 degradation by competitively binding to miR-216a-5p and enhancing neuroendocrine differentiation in prostate cancer

OBJECTIVES

Prostate cancer (PC) is a leading cause of cancer-related death in males worldwide. Neuroendocrine differentiation (NED) is a feature of PC that often goes undetected and is associated with poor patient outcomes. Long non-coding RNAs (lncRNAs), microRNAs (miRNAs/miRs), and messenger RNAs (mRNAs) play important roles in the development and progression of PC.

METHODS

In this study, we used transcriptome sequencing and bioinformatics analysis to identify key regulators of NED in PC. Specifically, we examined the expression of PC-related lncRNAs, miRNAs, and mRNAs in PC cells and correlated these findings with NED phenotypes.

RESULTS

Our data revealed that metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and zinc finger protein 91 (ZFP91) were upregulated in PC, while miR-216a-5p was down-regulated. Ectopic expression of MALAT1 induced NED and promoted malignant phenotypes of PC cells. Furthermore, we found that MALAT1 competitively bound to miR-216a-5p, upregulated ZFP91, and promoted the degradation of forkhead box A1 (FOXA1), a key gene involved in NED of PC.

CONCLUSION

Taken together, these results suggest that MALAT1 plays an oncogenic role in NED and metastasis of PC via the miR-216a-5p/ZFP91/FOXA1 pathway. Our study highlights the potential of targeting this pathway as a novel therapeutic strategy for PC.

Neuroendocrine differentiation predicts the therapeutic efficacy of abiraterone and docetaxel as first-line therapy in metastatic castration-resistant prostate cancer

PURPOSE

We aim to explore the predictive value of neuroendocrine differentiation (NED) in patients with metastatic castration-resistant prostate cancer (mCRPC) receiving abiraterone or docetaxel as first-line therapy.

METHODS

We retrospectively analyzed data of 262 mCRPC patients receiving abiraterone or docetaxel as first-line mCRPC treatment. NED was evaluated using prostate biopsy samples at the time of mCRPC by immunohistochemical staining. Kaplan-Meier curves and Cox regression were used to assess the association between NED and treatment outcomes including PSA progression-free survival (PSA-PFS), radiographic progression-free survival (rPFS), and overall survival (OS).

RESULTS

NED was confirmed in 100/262 (38.2%) mCRPC patients, with 76/100 (76.0%) and 24/100 (24.0%) men harboring NED < 10% and NED ≥ 10%, respectively. 203/262 (77.5%) and 59/262 (22.5%) patients received abiraterone and docetaxel, respectively. In abiraterone treatment, NED was associated with a significantly shorter median PSA-PFS (mPSA-PFS, 7.5 vs. 10.3-Mo, P < 0.001), median rPFS (mrPFS, 15.9 vs. 19.5-Mo, P = 0.010), and median OS (mOS, 23.2 vs. 34.3-Mo, P = 0.014)). Likewise, for mCRPC patients receiving docetaxel, the positive detection of NED also predicted shorter mPSA-PFS (3.8 vs. 5.9-Mo, P = 0.052), mrPFS (8.4 vs. 20.4-Mo, P = 0.016) and mOS (13.6 vs. 29.0-Mo, P = 0.033). The adverse prognostic trait of NED is consistent in most subgroups. Additionally, patients' survival outcomes deteriorated as the NED proportion grew in both therapies. After propensity score matching, NED-positive patients showed comparable prognosis in abiraterone and docetaxel therapy.

CONCLUSION

For mCRPC patients receiving abiraterone or docetaxel, NED and its proportion were critical predictive factors. NED detection at mCRPC might aid in predicting patients' outcomes and optimizing treatment decisions.

Plasma Chromogranin A as a Prognostic Marker in Pancreatic Ductal Adenocarcinoma

OBJECTIVES

Neuroendocrine differentiation in pancreatic ductal adenocarcinoma (PDAC) is known, but its clinical significance still remains uncertain. The clinical role of chromogranin A (CgA), a marker of neuroendocrine tumor, was evaluated in patients with PDAC.

METHODS

We retrospectively analyzed 350 patients with PDAC. All patients had plasma CgA levels at diagnosis. Patients were classified as normal and high CgA groups according to the upper limit of plasma CgA.

RESULTS

There were 202 patients (57.7%) in the normal CgA group and 148 patients (42.3%) in the high CgA group. High CgA group presented higher rate of metastatic disease (61.5% vs 45.0%; P = 0.002) and shorter median overall survival (OS) (8.2 vs 11.6 months; P = 0.015). Upon grouping patients based on clinical stages, OS was significantly different between the CgA groups only in metastatic disease (6.6 vs 7.2 months; P = 0.022). Multivariate analysis showed no association between high CgA and OS (hazard ratio, 1.22; 95% confidence interval, 0.97-1.54; P = 0.090). However, high CgA was associated with poor OS in patients with metastatic disease (hazard ratio, 1.37; 95% confidence interval, 1.01-1.87; P = 0.047).

CONCLUSIONS

High CgA levels may predict poor prognosis in patients with pancreatic cancer, especially during metastatic stages.

Focal Neuroendocrine Differentiation of Conventional Prostate Adenocarcinoma as a Prognostic Factor after Radical Prostatectomy: A Systematic Review and Meta-Analysis

The biologic and prognostic value of focal neuroendocrine differentiation (NED) in conventional prostate adenocarcinoma (PC) patients who undergo radical prostatectomy (RP) remains controversial. In this systematic review and meta-analysis, we assessed the association of focal NED in conventional PC with oncological outcomes after RP. A literature search using PubMed, Scopus, Web of Science, and Cochrane Library was conducted on December 2018 to find relevant studies according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. We used a fixed-effect model to analyze the impact of focal NED in RP specimen on progression-free survival defined by biochemical recurrence (BCR). A total of 16 studies with the outcomes of disease progression and survival were eligible. No patient in these studies received androgen deprivation therapy prior to RP. Eleven studies found no significant correlation between focal NED and outcomes of interest, while five studies reported a significant association of focal NED assessed by immunohistochemical chromogranin A or serotonin staining with BCR or survival. Focal NED was associated with higher BCR rates after RP with a pooled HR of 1.39 (95% CI 1.07‒1.81) in five studies. No heterogeneity was reported in this analysis (I² = 21.7%, p = 0.276). In conclusion, focal NED in conventional PC is associated with worse prognosis after RP. Its presence should be reported in pathologic reports and its true clinical impact should be assessed in well-designed prospective controlled studies.

Small-cell neuroendocrine cancer of the prostate: an atypical presentation of a common disease

A 70-year-old man with a history of prostate cancer, previously submitted to surgical castration and trans-urethral resection of the prostate, was admitted to Accident and Emergency department. He had been suffering from osteoarticular and abdominal pain, and recent weight loss. An abdominal and a pelvic CT showed multiple hepatic metastases and a pelvic mass, but his prostate-specific antigen values were low (0.26 n/mL). A biopsy of a hepatic metastasis and of the pelvic mass revealed a small-cell neuroendocrine prostate cancer, a rare and aggressive androgen-independent form of prostate cancer with a poor prognosis. Our purpose was to report a clinical case of a rare and aggressive variant of a common disease. A high index of suspicion is required to make an early diagnosis and to ensure a proper therapeutic approach.

The proliferation marker Ki67, but not neuroendocrine expression, is an independent factor in the prediction of prognosis of primary prostate cancer patients

Background

Neuroendocrine markers, which could indicate for aggressive variants of prostate cancer and Ki67 (a well-known marker in oncology for defining tumor proliferation), have already been associated with clinical outcome in prostate cancer. The aim of this study was to investigate the prognostic value of those markers in primary prostate cancer patients.

Patients and methods

NSE (neuron specific enolase), ChrA (chromogranin A), Syp (Synaptophysin) and Ki67 staining were performed by immunohistochemistry. Then, the prognostic impact of their expression on overall survival was investigated in 166 primary prostate cancer patients by univariate and multivariate analyses.

Results

NSE, ChrA, Syp and Ki67 were positive in 50, 45, 54 and 146 out of 166 patients, respectively. In Kaplan-Meier analysis only diffuse NSE staining (negative vs diffuse, p = 0.004) and Ki67 (≤ 10% vs > 10%, p < 0.0001) were significantly associated with overall survival. Ki67 expression, but not NSE, resulted as an independent prognostic factor for overall survival in multivariate analysis.

Conclusions

A prognostic model incorporating Ki67 expression with clinical-pathological covariates could provide additional prognostic information. Ki67 may thus improve prediction of prostate cancer outcome based on standard clinical-pathological parameters improving prognosis and management of prostate cancer patients.

The cannabinoid WIN 55,212-2 prevents neuroendocrine differentiation of LNCaP prostate cancer cells

BACKGROUND:

Neuroendocrine (NE) differentiation represents a common feature of prostate cancer and is associated with accelerated disease progression and poor clinical outcome. Nowadays, there is no treatment for this aggressive form of prostate cancer. The aim of this study was to determine the influence of the cannabinoid WIN 55,212-2 (WIN, a non-selective cannabinoid CB1 and CB2 receptor agonist) on the NE differentiation of prostate cancer cells.

METHODS:

NE differentiation of prostate cancer LNCaP cells was induced by serum deprivation or by incubation with interleukin-6, for 6 days. Levels of NE markers and signaling proteins were determined by western blotting. Levels of cannabinoid receptors were determined by quantitative PCR. The involvement of signaling cascades was investigated by pharmacological inhibition and small interfering RNA.

RESULTS:

The differentiated LNCaP cells exhibited neurite outgrowth, and increased the expression of the typical NE markers neuron-specific enolase and βIII tubulin (βIII Tub). Treatment with 3 μM WIN inhibited NK differentiation of LNCaP cells. The cannabinoid WIN downregulated the PI3K/Akt/mTOR signaling pathway, resulting in NE differentiation inhibition. In addition, an activation of AMP-activated protein kinase (AMPK) was observed in WIN-treated cells, which correlated with a decrease in the NE markers expression. Our results also show that during NE differentiation the expression of cannabinoid receptors CB1 and CB2 dramatically decreases.

CONCLUSIONS:

Taken together, we demonstrate that PI3K/Akt/AMPK might be an important axis modulating NE differentiation of prostate cancer that is blocked by the cannabinoid WIN, pointing to a therapeutic potential of cannabinoids against NE prostate cancer.

Molecular aspects of prostate cancer with neuroendocrine differentiation

Neuroendocrine differentiation (NED), which is not uncommon in prostate cancer, is increases in prostate cancer after androgen-deprivation therapy (ADT) and generally appears in castration-resistant prostate cancer (CRPC). Neuroendocrine cells, which are found in normal prostate tissue, are a small subset of cells and have unique function in regulating the growth of prostate cells. Prostate cancer with NED includes different types of tumor, including focal NED, pure neuroendocrine tumor or mixed neuroendocrine-adenocarcinoma. Although more and more studies are carried out on NED in prostate cancer, the molecular components that are involved in NED are still poorly elucidated. We review neuroendocrine cells in normal prostate tissue, NED in prostate cancer, terminology of NED and biomarkers used for detecting NED in routine pathological practice. Some recently reported molecular components which drive NED in prostate cancer are listed in the review.

Targeting neuroendocrine prostate cancer: molecular and clinical perspectives

Neuroendocrine prostate carcinoma, either co-present with the local adenocarcinoma disease or as a result of transdifferentiation later in time, was described as one major process of emerging resistance to androgen deprivation therapies, and at the clinical level it is consistent with the development of rapidly progressive visceral disease, often in the absence of elevated serum prostate-specific antigen level. Until present, platinum-based chemotherapy has been the only treatment modality, able to produce a fair amount of responses but of short duration. Recently, several efforts for molecular characterization of this lethal phenotype have resulted in identification of novel signaling factors involved in microenvironment interactions, mitosis, and neural reprograming as potential therapeutic targets. Ongoing clinical testing of specific inhibitors of these targets, for example, Aurora kinase A inhibitors, in carefully selected patients and exploitation of expression changes of the target before and after manipulation is anticipated to increase the existing data and facilitate therapeutic decision making at this late stage of the disease when hormonal manipulations, even with the newest androgen-directed therapies are no longer feasible.