Neuroendocrine expression in node positive prostate cancer: correlation with systemic progression and patient survival

Patient-Derived Conditionally Reprogrammed Cells in Prostate Cancer Research

Prostate cancer (PCa) remains a leading cause of mortality among American men, with metastatic and recurrent disease posing significant therapeutic challenges due to a limited comprehension of the underlying biological processes governing disease initiation, dormancy, and progression. The conventional use of PCa cell lines has proven inadequate in elucidating the intricate molecular mechanisms driving PCa carcinogenesis, hindering the development of effective treatments. To address this gap, patient-derived primary cell cultures have been developed and play a pivotal role in unraveling the pathophysiological intricacies unique to PCa in each individual, offering valuable insights for translational research. This review explores the applications of the conditional reprogramming (CR) cell culture approach, showcasing its capability to rapidly and effectively cultivate patient-derived normal and tumor cells. The CR strategy facilitates the acquisition of stem cell properties by primary cells, precisely recapitulating the human pathophysiology of PCa. This nuanced understanding enables the identification of novel therapeutics. Specifically, our discussion encompasses the utility of CR cells in elucidating PCa initiation and progression, unraveling the molecular pathogenesis of metastatic PCa, addressing health disparities, and advancing personalized medicine. Coupled with the tumor organoid approach and patient-derived xenografts (PDXs), CR cells present a promising avenue for comprehending cancer biology, exploring new treatment modalities, and advancing precision medicine in the context of PCa. These approaches have been used for two NCI initiatives (PDMR: patient-derived model repositories; HCMI: human cancer models initiatives).

Imaging of Neuroendocrine Prostatic Carcinoma

Neuroendocrine prostate cancer (NEPC) is an aggressive subtype of prostate cancer that typically has a high metastatic potential and poor prognosis in comparison to the adenocarcinoma subtype. Although it can arise de novo, NEPC much more commonly occurs as a mechanism of treatment resistance during therapy for conventional prostatic adenocarcinoma, the latter is also termed as castration-resistant prostate cancer (CRPC). The incidence of NEPC increases after hormonal therapy and they represent a challenge, both in the radiological and pathological diagnosis, as well as in the clinical management. This article provides a comprehensive imaging review of prostatic neuroendocrine tumors.

Neuroendocrine cells in prostate cancer correlate with poor outcomes: a systematic review and meta-analysis

OBJECTIVES

To perform a systematic review and meta-analysis of the literature to understand the variation in the reporting of neuroendocrine staining and determine the influence of reporting neuroendocrine staining at diagnosis on patient outcomes.

METHODS

Medical databases were searched to identify studies in which adenocarcinoma specimens were stained with any of the following four neuroendocrine markers: chromogranin A (CgA), neuron-specific enolase (NSE), synaptophysin and CD56. The prevalence of neuroendocrine staining and correlation of the prevalence of neuroendocrine staining to patient outcomes were analysed using a random-effects model. All statistical tests were two-sided.

RESULTS

Sixty-two studies spanning 7616 patients were analysed. The pooled prevalence for the most common marker, CgA (41%), was similar to that of NSE (39%) and higher than that of synaptophysin (31%). The prevalence of CgA staining was significantly influenced by reporting criteria, where objective thresholds reduced the variation in prevalence to 26%. No correlation was found between CgA prevalence and tumour grade. Patients positive for CgA staining using objective criteria had more rapid biochemical progression (hazard ratio [HR] 1.98, 95% confidence interval [CI] 1.49 to 2.65) and poorer prostate cancer-specific survival (HR 7.03, 95% CI 2.55 to 19.39) compared to negative patients, even among those with low-risk cancers.

CONCLUSION

Discrepancies in the reported prevalence of neuroendocrine cells in adenocarcinoma are driven by the inconsistent scoring criteria. This study unequivocally demonstrates that when neuroendocrine cell staining is assessed with objective criteria it identifies patients with poor clinical outcomes. Future studies are needed to determine the exact quantifiable thresholds for use in reporting neuroendocrine cell staining to identify patients at higher risk of progression.

Application of extracellular vesicles in the diagnosis and treatment of prostate cancer: Implications for clinical practice

Extracellular vesicles (EV) are cell-derived lipid bilayer-delimited structures providing an important means of intercellular communication. Recent studies have shown that EV, particularly exosomes and large-oncosomes contain miRNA and proteins crucial in prostate cancer (PCa) progression, metastasis and treatment resistance. This includes not just EV released from PCa cells, but also from other cells in the tumor microenvironment. PCa patient derived EV have a unique composition compared to healthy and benign prostatic diseases. As such, EV show promise as diagnostic liquid biopsy biomarkers, both as an adjunct and alternative to the invasive current gold-standard. EV could also be utilized to stratify patients' risk and predict response to hormonal, chemo, immune- and targeted therapy, which will direct future treatment decisions in PCa. We present a summary of the current evidence on the role of EV in PCa and the application of EV in PCa diagnosis and treatment to optimize patient outcomes.

Investigation of the Prognostic Significance of Neuroendocrine Differentiation in Gleason Score 7 to 10 Prostate Adenocarcinoma in Patients With Distant Metastasis After Definitive Radiotherapy

OBJECTIVES

We investigated the prognostic implications of neuroendocrine differentiation (NED) in prostate adenocarcinoma detected by chromogranin A (CgA) in patients who developed distant metastasis (DM) after radiotherapy.

METHODS

Patients with Gleason score 7 to 10 conventional acinar prostate adenocarcinoma treated with definitive radiotherapy and with core biopsy CgA staining completed were reviewed. Patients who developed DM, defined as disease beyond the primary tumor or pelvic lymph nodes, underwent detailed chart review. Statistical analysis included Kaplan-Meier estimates and descriptive statistics to compare based on quantification of CgA staining.

RESULTS

Thirty-five patients had confirmed DM. Twenty-five patients had less than 1% of cells staining positive for CgA, and 10 patients had more than 1%. Median overall survival (OS) time was 3.26 and 1.04 years, respectively (P = .52). Median cause-specific survival (CSS) was 6.15 and 1.04 years, respectively (P = .21). Fifty-six percent of patients with CgA less than 1% died of prostate cancer compared with 90% of those with CgA more than 1% (P = .059). There were no significant differences in sites of metastatic disease or administration of systemic therapies.

CONCLUSIONS

No significant differences in OS and CSS were observed based on NED detected by CgA. Reduced median survival time and increased cancer-related death in cases with focal NED generates the hypothesis of inferior outcomes among patients with documented DM.

Serotonin Pathway in Cancer

Serotonin (5-hydroxytryptamine, 5-HT) is a biogenic monoamine produced from the essential amino acid tryptophan. Serotonin's role as a neurotransmitter in the central nervous system and a motility mediator in the gastrointestinal tract has been well defined, and its function in tumorigenesis in various cancers (gliomas, carcinoids, and carcinomas) is being studied. Many studies have shown a potential stimulatory effect of serotonin on cancer cell proliferation, invasion, dissemination, and tumor angiogenesis. Although the underlying mechanism is complex, it is proposed that serotonin levels in the tumor and its interaction with specific receptor subtypes are associated with disease progression. This review article describes serotonin's role in cancer pathogenesis and the utility of the serotonin pathway as a potential therapeutic target in cancer treatment. Octreotide, an inhibitor of serotonin release, is used in well-differentiated neuroendocrine cancers, and the tryptophan hydroxylase (TPH) inhibitor, telotristat, is currently being investigated in clinical trials to treat patients with metastatic neuroendocrine tumors and advanced cholangiocarcinoma. Several in vitro studies have shown the anticancer effect of 5-HT receptor antagonists in various cancers such as prostate cancer, breast cancer, urinary bladder, colorectal cancer, carcinoid, and small-cell lung cancer. More in vivo studies are needed to assess serotonin's role in cancer and its potential use as an anticancer therapeutic target. Serotonin is also being evaluated for its immunoregulatory properties, and studies have shown its potential anti-inflammatory effect. Therefore, it would be of interest to explore the combination of serotonin antagonists with immunotherapy in the future.

Development and prevalence of castration-resistant prostate cancer subtypes

BACKGROUND

Castration-resistant prostate cancer (CRPC) occurs when prostate cancer (CaP) progresses under therapy-induced castrate conditions. Several mechanisms have been proposed to explain this acquired resistance, many of which are driven by androgen receptor (AR). Recent findings, however, sub-classified CRPC by downregulation/absence of AR in certain subtypes that consequently do not respond to anti-androgen therapies. To highlight the significance of CRPC sub-classification, we reviewed the development and treatment of CRPC, AR downregulation in CRPC, and summarized recent reports on the prevalence of CRPC subtypes.

METHODS

Using a medline-based literature search, we reviewed mechanisms of CRPC development, current treatment schemes, and assessed the prevalence of AR low/negative subtypes of CRPC. Additionally, we performed immunohistochemical staining on human CRPC specimens to quantify AR expression across CRPC subtypes.

RESULTS

In the majority of cases, CRPC continues to rely on AR signaling, which can be augmented in castrate-conditions through a variety of mechanisms. However, recently low/negative AR expression patterns were identified in a significant proportion of patient samples from a multitude of independent studies. In these AR low/negative cases, we postulated that AR protein may be downregulated by (1) promoter methylation, (2) transcriptional regulation, (3) post-transcriptional regulation by microRNA or RNA-binding-proteins, or (4) post-translational ubiquitination-mediated degradation.

CONCLUSIONS

Here, we discussed mechanisms of CRPC development and summarized the overall prevalence of CRPC subtypes; interestingly, AR low/negative CRPC represented a considerable proportion of diagnoses. Because these subtypes cannot be effectively treated with AR-targeted therapeutics, a better understanding of AR low/negative subtypes could lead to better treatment strategies and increased survival.

Neuroendocrine differentiation in usual-type prostatic adenocarcinoma: Molecular characterization and clinical significance

BACKGROUND

Small cell neuroendocrine (NE) carcinomas of the prostate classically lose androgen receptor (AR) expression, may harbor loss of the RB1, TP53, and PTEN tumor suppressor genes, and are associated with a poor prognosis. However usual-type adenocarcinomas may also contain areas of NE differentiation, and in this context the molecular features and biological significance are less certain.

METHODS

We examined the molecular phenotype and oncologic outcomes of primary prostate adenocarcinomas with ≥5% NE differentiation (≥5% chromogranin A-positive NE cells in any given tumor spot on tissue microarray) using three independent study sets: a set of tumors with paneth cell-like NE differentiation (n = 26), a retrospective case-cohort of intermediate- and high-risk patients enriched for adverse outcomes (n = 267), and primary tumors from a retrospective series of men with eventual castration-resistant metastatic prostate cancer (CRPC) treated with abiraterone or enzalutamide (n = 55).

RESULTS

Benign NE cells expressed significantly lower quantified AR levels compared with paired benign luminal cells (P < .001). Similarly, paneth-like NE carcinoma cells or carcinoma cells expressing chromogranin A expressed significantly lower quantified AR levels than paired non-NE carcinoma cells (P < .001). Quantified ERG protein expression, was also lower in chromogranin A-labeled adenocarcinoma cells compared with unlabeled cells (P < .001) and tumors with NE differentiation showed lower gene expression scores for AR activity compared with those without. Despite evidence of lower AR signaling, adenocarcinomas with NE differentiation did not differ by prevalence of TP53 missense mutations, or PTEN or RB1 loss, compared with those without NE differentiation. Finally, NE differentiation was not associated with time to metastasis in intermediate- and high-risk patients (P = .6 on multivariate analysis), nor with progression-free survival in patients with CRPC treated with abiraterone or enzalutamide (P = .9).

CONCLUSION

NE differentiation in usual-type primary prostate adenocarcinoma is a molecularly and clinically distinct form of lineage plasticity from that occurring in small cell NE carcinoma.

Response Prediction of 177Lu-PSMA-617 Radioligand Therapy Using Prostate-Specific Antigen, Chromogranin A, and Lactate Dehydrogenase

Neuroendocrinelike transdifferentiation of prostate cancer adenocarcinomas correlates with serum levels of chromogranin A (CgA) and drives treatment resistance. The aim of this work was to evaluate whether CgA can serve as a response predictor for ¹⁷⁷Lu-prostate-specific membrane antigen 617 (PSMA) radioligand therapy (RLT) in comparison with the established tumor markers. Methods: One hundred consecutive patients with metastasized castration-resistant prostate cancer scheduled for PSMA RLT were evaluated for prostate-specific antigen (PSA), lactate dehydrogenase (LDH), and CgA at baseline and in follow-up of PSMA RLT. Tumor uptake of PSMA ligand, a known predictive marker for response, was assessed as a control variable. Results: From the 100 evaluated patients, 35 had partial remission, 16 stable disease, 15 mixed response, and 36 progression of disease. Tumor uptake above salivary gland uptake translated into partial remission, with an odds ratio (OR) of 60.265 (95% confidence interval [CI], 5.038-720.922). Elevated LDH implied a reduced chance for partial remission, with an OR of 0.094 (95% CI, 0.017-0.518), but increased the frequency of progressive disease (OR, 2.717; 95% CI, 1.391-5.304). All patients who achieved partial remission had a normal baseline LDH. Factor-2 elevation of CgA increased the risk for progression, with an OR of 3.089 (95% CI, 1.302-7.332). Baseline PSA had no prognostic value for response prediction. Conclusion: In our cohort, baseline PSA had no prognostic value for response prediction. LDH was the marker with the strongest prognostic value, and elevated LDH increased the risk for progression of disease under PSMA RLT. Elevated CgA demonstrated a moderate impact as a negative prognostic marker in general but was explicitly related to the presence of liver metastases. Well in line with the literature, sufficient tumor uptake is a prerequisite to achieve tumor response.

Low-serum prostate-specific antigen level predicts poor outcomes in patients with primary neuroendocrine prostate cancer

BACKGROUND

The rarities of primary neuroendocrine prostate cancer (NEPC) and primary adenocarcinoma with neuroendocrine differentiation (NE differentiation) mean that their clinical characteristics have not been fully elucidated.

MATERIALS AND METHODS

A total of 449 patients with NEPC, including 352 cases of pure NEPC and 97 cases of NE differentiation, together with 408 629 cases of prostate adenocarcinoma at diagnosis were retrieved from the Surveillance, Epidemiology, and End Results program (2010-2015). Clinical parameters and prognoses were compared between patients with different histological types of NEPC using the χ² test and Kaplan-Meier analysis, respectively. The prognostic value of prostate-specific antigen (PSA) in NEPC and adenocarcinoma was evaluated using Cox regression and the Kaplan-Meier method.

RESULTS

Pure NEPC had higher rates of visceral metastases (brain, lung, and liver: 4.58%, 26.72%, and 36.64%, respectively) but a lower rate of bone metastasis (65.65%) compared with NE differentiation and prostate adenocarcinoma. Moreover, patients diagnosed with pure NEPC had a poorer outcome (median survival time: 10 months) compared with patients with NE differentiation (26 months) and prostate adenocarcinoma (median survival time not reached). Using PSA 4.1 to 10 ng/mL as the reference, the adjusted hazard ratios (HRs) for PSA lower than or equal to 4.0 ng/mL were 2.24 (95% confidence interval [CI]: 1.11-4.55, P = .025) in the NE differentiation group and 1.57 (95% CI: 1.11-2.23, P = .011) in the pure NEPC group.

CONCLUSIONS

Patients with NE differentiation had different clinical characteristics and a better prognosis than patients with pure NEPC. In addition, low-serum PSA levels were associated with a poorer prognosis in patients with either NEPC or NE differentiation.

ZBTB46, SPDEF, and ETV6: Novel Potential Biomarkers and Therapeutic Targets in Castration-Resistant Prostate Cancer

Prostate cancer (PCa) is the second most common killer among men in Western countries. Targeting androgen receptor (AR) signaling by androgen deprivation therapy (ADT) is the current therapeutic regime for patients newly diagnosed with metastatic PCa. However, most patients relapse and become resistant to ADT, leading to metastatic castration-resistant PCa (CRPC) and eventually death. Several proposed mechanisms have been proposed for CRPC; however, the exact mechanism through which CRPC develops is still unclear. One possible pathway is that the AR remains active in CRPC cases. Therefore, understanding AR signaling networks as primary PCa changes into metastatic CRPC is key to developing future biomarkers and therapeutic strategies for PCa and CRPC. In the current review, we focused on three novel biomarkers (ZBTB46, SPDEF, and ETV6) that were demonstrated to play critical roles in CRPC progression, epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI) drug resistance, and the epithelial-to-mesenchymal transition (EMT) for patients treated with ADT or AR inhibition. In addition, we summarize how these potential biomarkers can be used in the clinic for diagnosis and as therapeutic targets of PCa.

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.

Evolving concepts in prostatic neuroendocrine manifestations: from focal divergent differentiation to amphicrine carcinoma

Prostatic neuroendocrine manifestations encompass a heterogeneous spectrum of morphologic entities. In the era of evidence-based and precision-led treatment, distinction of biologically relevant clinical manifestations expanded the evolving clinical role of pathologists. Recent observations on the occurrence of hormone therapy-induced aggressive prostatic cancers with neuroendocrine features have triggered the need to refine the spectrum and nomenclature of prostatic neuroendocrine manifestations. Although the morphologic assessment still remains the basis of the diagnostic workup of prostatic neoplasms, the application of ancillary biomarkers is crucial in the accurate classification of such presentations. This review provides a diagnostic roadmap for the practicing pathologist by reviewing the characteristic morphologic, immunohistochemical, and molecular correlates of various faces of prostatic neuroendocrine manifestations.

Analysis of Gastric Carcinoma With Neuroendocrine Character

The clinical significance of gastric adenocarcinoma with neuroendocrine differentiation is unclear because of its rarity. The aim of this study was to suggest a treatment strategy for this tumor. A total of 10 resected gastric tumors with neuroendocrine character, including 3 neuroendocrine carcinomas (NECs) and 7 adenocarcinomas with neuroendocrine differentiation, were retrospectively reviewed regarding tumor characteristics and therapeutic outcomes. The gastric adenocarcinomas with neuroendocrine differentiation had high rates of lymph node metastasis and vessel invasion, and showed the poor prognoses as NEC. The median survival time (MST) was 13 months. Preoperative and postoperative chemotherapy tended to prolong the MST compared with operation alone (112.5 versus 5 months; P = 0.058). Moreover, chemotherapy for postoperative recurrence significantly contributed to improving prognosis (MST, 15 versus 7 months; P = 0.025). Gastric adenocarcinoma with neuroendocrine differentiation had equivalently high potential malignancy as NEC. More aggressive treatment should be considered for this tumor according to NEC.

Neuroendocrine Differentiation in Metastatic Conventional Prostate Cancer Is Significantly Increased in Lymph Node Metastases Compared to the Primary Tumors

Neuroendocrine serum markers released from prostate cancers have been proposed for monitoring disease and predicting survival. However, neuroendocrine differentiation (NED) in various tissue compartments of metastatic prostate cancer is poorly described and its correlation with specific tumor features is unclear. NED was determined by Chromogranin A expression on immunostains from a tissue microarray of 119 nodal positive, hormone treatment-naïve prostate cancer patients who underwent radical prostatectomy and extended lymphadenectomy. NED in the primary cancer and in the metastases was correlated with tumor features and survival. The mean percentage of NED cells increased significantly (p < 0.001) from normal prostate glands (0.4%), to primary prostate cancer (1.0%) and nodal metastases (2.6%). In primary tumors and nodal metastases, tumor areas with higher Gleason patterns tended to display a higher NED, although no significance was reached. The same was observed in patients with a larger primary tumor volume and higher total size and number of metastases. NED neither in the primary tumors nor in the metastases predicted outcome significantly. Our data suggest that (a) increasing levels of neuroendocrine serum markers in the course of prostate cancer might primarily derive from a poorly differentiated metastatic tumor component; and (b) NED in conventional hormone-naïve prostate cancers is not significantly linked to adverse tumor features.

Exposure to maternal obesogenic diet worsens some but not all pre-cancer phenotypes in a murine genetic model of prostate cancer

Prostate cancer research has been predominantly focused on adult exposures and risk factors. However, because the prostate develops during gestation and early life, exposure to external factors, such as obesity, during development could affect the prostate cancer progression in adults. Our previous work demonstrated that exposure to a high fat/high sugar (HF/HS) diet during gestation and until weaning stimulated prostate hyperplasia and altered the Pten/Akt pathway in adult mice fed a normal diet after weaning. Here, we asked whether maternal exposure to HF/HS would worsen prostate phenotypes in mice lacking Pten, a widely accepted driver of prostate cancer. We found that, at six weeks of age, both Chow (control)-and HF/HS-exposed Pten knockout mice showed evidence of murine PIN that included ducts with central comedo necrosis but that the HF/HS exposure did not influence murine PIN progression. The Pten knockout mice exposed to HF/HS in utero had significantly more mitotic cells than Pten knockouts exposed to Chow diet. In the Pten null background, the maternal HF/HS diet enhanced proliferation but did not have an additive effect on Akt activation. We observed neuroendocrine differentiation in Pten knockout mice, a phenotype that had not been previously described in this model.

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

BACKGROUND

The multiple pathways that are involved in neuroendocrine differentiation (NED) in prostate cancer (PCa) are poorly elucidated. Evidence suggests that several environmental triggers induce NED leading to the adaptation of PCa to its close environment to maintain cell proliferation. Nevertheless, there is conflicting evidence regarding the prognostic role of NED in PCa.

METHODS

In this review, we aimed to summarize all available data about NED and to assess the prognostic role of NED in disease progression and therapy resistance, and its role in routine clinical practice. This review was based on articles found through a PubMed literature search between 1993 and 2013. The study outcome measure was the effect of NED on oncologic outcomes at each PCa stage.

RESULTS

In total, 59 articles reporting on the effect of NED on oncologic outcomes have been selected. In clinical practice, immunostaining for NED markers could have interesting predictive value for assessing the oncologic outcomes in patients receiving androgen-deprivation therapy. Thus, patients with high NED burden may be candidates for more aggressive treatment strategies targeting NED pathways. Conversely, strong evidence is lacking concerning its potential independent prognostic value in hormone-naïve PCa.

CONCLUSIONS

Current published data are not sufficient to recommend the use of NE markers in routine practice, particularly at early PCa stage.

Chromogranin A staining as a prognostic variable in newly diagnosed Gleason score 7-10 prostate cancer treated with definitive radiotherapy

PURPOSE

To demonstrate the association of neuroendocrine differentiation, as identified by chromogranin A (CgA) staining, with clinical outcomes in newly diagnosed prostatic adenocarcinoma treated with definitive radiotherapy (RT).

MATERIALS/METHODS

Patients with Gleason score ≥7 adenocarcinoma were identified from our outcomes database. RT consisted of external beam, brachytherapy, or external beam with brachytherapy boost. Biopsy specimens were stained for neuroendocrine differentiation with CgA. Results were interpreted by a single pathologist. CgA staining was quantified as 0%, <1%, 1-10%, or >10% of tumor cells. Clinical outcomes were blinded at the time of pathologic evaluation.

RESULTS

CgA staining was performed on 289 patients. 149 patients had Gleason score 7, and 140 were Gleason score 8-10. Median follow-up was 6.5 years. For patients with <1% versus >1% CgA staining, pretreatment characteristics were well-balanced. CgA staining was detected in 90 cases (31%). 58 patients had focal positive (<1%) CgA staining, and 32 cases had >1% of tumor cells CgA positive. Patients with >1% CgA staining had inferior biochemical control, clinical failure, distant metastases (DM), and cause-specific survival (CSS) rates. Ten-year rates of DM were 8% versus 48% for patients with <1% versus >1% CgA positive cells, respectively (P < 0.001). CSS at 10 years was 95% versus 76%, respectively (P < 0.001). Local control was equivalent in the two patient cohorts. Patients with <1% CgA staining had similar outcomes to those patients with 0% staining.

CONCLUSIONS

Neuroendocrine differentiation involving >1% of tumor cells on prostate cancer biopsies is a predictor of DM and CSS in patients treated with primary RT.

Germline genetic variation modulates tumor progression and metastasis in a mouse model of neuroendocrine prostate carcinoma

Neuroendocrine (NE) differentiation has gained increased attention as a prostate cancer (PC) prognostic marker. The aim of this study is to determine whether host germline genetic variation influences tumor progression and metastasis in C57BL/6-Tg(TRAMP)8247Ng/J (TRAMP) mouse model of aggressive NEPC. TRAMP mice were crossed to the eight progenitor strains of the Collaborative Cross recombinant inbred panel to address this. Tumor growth and metastasis burden were quantified in heterozygous transgene positive F1 male mice at 30 weeks of age. Compared to wild-type C57BL/6J-Tg(TRAMP)824Ng/J males, TRAMP x CAST/EiJ, TRAMP x NOD/ShiLtJ and TRAMP x NZO/HlLtJ F1 males displayed significant increases in tumor growth. Conversely, TRAMP x WSB/EiJ and TRAMP x PWK/PhJ F1 males displayed significant reductions in tumor growth. Interestingly, despite reduced tumor burden, TRAMP x WSB/EiJ males had an increased nodal metastasis burden. Patterns of distant pulmonary metastasis tended to follow the same patterns as that of local dissemination in each of the strains. All tumors and metastases displayed positive staining for NE markers, synaptophysin, and FOXA2. These experiments conclusively demonstrate that the introduction of germline variation by breeding modulates tumor growth, local metastasis burden, and distant metastasis frequency in this model of NEPC. These strains will be useful as model systems to facilitate the identification of germline modifier genes that promote the development of aggressive forms of PC.

The role of Snail in prostate cancer

Prostate cancer is the second most frequently diagnosed cancer and the sixth leading cause of death from cancer in men. Epithelial-mesenchymal transition (EMT) is a process by which cancer cells invade and migrate, and is characterized by loss of cell-cell adhesion molecules such as E-cadherin and increased expression of mesenchymal proteins such as vimentin; EMT is also associated with resistance to therapy. Snail, a master regulator of EMT, has been extensively studied and reported in cancers such as breast and colon; however, its role in prostate cancer is not as widely reported. The purpose of this review is to put together recent facts that summarize Snail signaling in human prostate cancer. Snail is overexpressed in prostate cancer and its expression and activity is controlled via phosphorylation and growth factor signaling. Snail is involved in its canonical role of inducing EMT in prostate cancer cells; however, it plays a role in non-canonical pathways that do not involve EMT such regulation of bone turnover and neuroendocrine differentiation. Thus, studies indicate that Snail signaling contributes to prostate cancer progression and metastasis and therapeutic targeting of Snail in prostate cancer holds promise in future.

Prognostic significance of neuroendocrine differentiation in prostate adenocarcinoma

Much progress has been made toward an understanding of the development and progression of prostate cancer (PC) and the factors that drive the development of androgen independence. Neuroendocrine (NE) cells may provide an intriguing link between NE cell differentiation (NED) and tumor progression in PC. NED in PC generally confers a more aggressive clinical behavior and less favorable prognosis than conventional PC. In this article, we review the known functions of NE cells in PC and discuss the current knowledge on stimulation of cancer proliferation, invasion, apoptosis resistance, serum and immunohistochemical markers, and the prognostic significance of NED in human PC.

Neuroendocrine tumor cells in prostate cancer: evaluation of the neurosecretory products serotonin, bombesin, and gastrin - impact on angiogenesis and clinical follow-up

BACKGROUND

Neuroendocrine differentiated tumor cells (NETC) can be found in a large portion of prostate carcinoma (PCa) specimens. This is the first study to systematically quantify and analyze the influence of the NETC distribution and of their secretory products, serotonin, bombesin, and gastrin, on angiogenesis and in the clinical follow-up of PCa patients.

METHODS

175 PCa specimens were included in this study. NETC were displayed using the marker CgA. Specimens showing a high expression of CgA were analyzed for serotonin, bombesin, and gastrin. Blood vessels were stained with the epitope CD34. Data was analyzed for inter-correlation and its correlation to clinical-pathological parameters and the results of a mid-term follow-up.

RESULTS

The number of NETC was correlated with the pT-status and the Gleason score. Specimens with high NETC expression had an increased microvessel density (MVD). No correlation between the neurosecretory products and the clinical-pathological parameters was found. High NETC expression, high bombesin expression and increased MVD were associated with early treatment failure in the follow-up.

CONCLUSION

NETC have an influence on angiogenesis and are correlated with the clinical-pathological parameters. A high expression of NETC is associated with an early failure of treatment. Our study underlines the importance of NETC in prostate cancer.

High CD10 expression in lymph node metastases from surgically treated prostate cancer independently predicts early death

Patients with nodal positive prostate cancers are an important cohort with poorly defined risk factors. CD10 is a cell surface metallopeptidase that has been suggested to play a role in prostate cancer progression. CD10 expression was evaluated in 119 nodal positive prostate cancer patients using tissue microarrays constructed from primary tumors and lymph node metastases. All patients underwent radical prostatectomy and standardized extended lymphadenectomy. They had no neoadjuvant therapy and received deferred androgen deprivation. In the primary tumor, high CD10 expression was significantly associated with earlier death from disease when compared with low CD10 expression (5-year survival 73.7% vs. 91.8%; p = 0.043). In the metastases, a high CD10 expression was significantly associated with larger total size of metastases (median 11.4 vs. 6.5 mm; p = 0.015), earlier death of disease (5-year survival 71.5% vs. 87.3%; p = 0.017), and death of any cause (5-year survival 70.0% vs. 87.2%; p = 0.001) when compared with low CD10 expression. CD10 expression in the metastases added independent prognostic information for overall survival (p = 0.029) after adjustment for Gleason score of the primary tumor, nodal tumor burden, and resection margins. In conclusion, a high CD10 expression in prostate cancer predicts early death. This information is inherent in the primary tumors and in the lymph node metastases and might help to personalize patient management.

Gastrin-releasing peptide: predictor of castration-resistant prostate cancer?

BACKGROUND

Neuroendocrine (NE) cells of the prostate are known to be androgen-independent and NE peptides like gastrin-releasing peptide (GRP) or neuron-specific enolase (NSE) can stimulate growth in a paracrine manner, and this is thought to be one of the escape mechanisms in castration-resistant prostate cancer (CRPCa). In a longitudinal study, we investigated the development of the NE serum factors GRP, NSE, and chromogranin A and their correlation with prostate-specific androgen (PSA) during hormonal treatment.

MATERIALS AND METHODS

Thirty two patients, with histology-proven, localized or metastatic prostatic carcinoma (PCa), who were undergoing therapy with LHRH analogue or a combination of LHRH analog and peripheral androgen blockade, took part in the study. In addition, eight healthy volunteers were each tested twice for serum GRP to elicit a "physiological" standard value. Blood samples were taken periodically from each patient within an 18-month time frame.

RESULTS

We defined the standard value for GRP in the healthy participants as 0.852 ng/ml (mean  +  2 SD) and observed that the GRP values for patients with PCa were significantly higher (P = 0.034). There was a positive correlation between PSA and GRP in patients with biochemical failure. CgA correlated with PSA development in the CRPCa patients. NSE values rose steadily over the study period, but with no correlation to PSA.

CONCLUSION

Our data confirm that NE factors are elevated during hormonal treatment of prostate cancer. GRP is higher in PCa patients undergoing androgen deprivation therapy and is possibly involved in the initiation of hormonal escape in PCa.

Snail transcription factor regulates neuroendocrine differentiation in LNCaP prostate cancer cells

BACKGROUND

Snail transcription factor induces epithelial-mesenchymal transition (EMT) via decreased cell adhesion-associated molecules like E-cadherin, and increased mesenchymal markers like vimentin. We previously established Snail-mediated EMT model utilizing androgen-dependent LNCaP cells. These cells express increased vimentin protein and relocalization of E-cadherin from the cell membrane to the cytosol. Interestingly, Snail transfection in LNCaP cells resulted in cells acquiring a neuroendocrine (NE)-like morphology with long neurite-like processes.

METHODS

We tested for expression of NE markers neuron-specific enolase (NSE) and chromogranin A (CgA) by Western blot analysis, and performed proliferation assays to test for paracrine cell proliferation.

RESULTS

LNCaP cells transfected with Snail displayed increase in the NE markers, NSE and CgA as well as translocation of androgen receptor (AR) to the nucleus. LNCaP C-33 cells that have been previously published as a neuroendocrine differentiation (NED) model exhibited increased expression levels of Snail protein as compared to LNCaP parental cells. Functionally, conditioned medium from the LNCaP-Snail transfected cells increased proliferation of parental LNCaP and PC-3 cells, which could be abrogated by NSE/CgA siRNA. Additionally, NED in LNCaP-C33 cells or that induced in parental LNCaP cells by serum starvation could be inhibited by knockdown of Snail with siRNA.

CONCLUSION

Overall our data provide evidence that Snail transcription factor may promote tumor aggressiveness in the LNCaP cells through multiple processes; induction of EMT may be required to promote migration, while NED may promote tumor proliferation by a paracrine mechanism. Therefore, therapeutic targeting of Snail may prove beneficial in not only abrogating EMT but also NED.

The prognostic role of immunohistochemical chromogranin a expression in prostate cancer patients is significantly modified by androgen-deprivation therapy

BACKGROUND

Several data suggest that neuroendocrine (NE) differentiation in prostate cancer is implicated in the development of resistance to androgen-deprivation therapy (ADT). This study was undertaken to assess the prognostic role of tissue chromogranin A (CgA) expression in patients addressed to ADT as opposed to those who did not.

METHODS

Four hundred fourteen newly diagnosed prostate cancer patients, consecutively recruited in a single institution, entered the study. Two hundred fourteen patients received ADT early after diagnosis, 200 did not. Median follow-up was 85 months. CgA expression was evaluated immunohistochemically in prostate cancer needle biopsies.

RESULTS

In multivariate analysis after adjusting for Gleason score, serum PSA, disease stage and local treatments, tissue CgA expression in overall cases was significantly associated with a shorter survival (P = 0.009) but failed to be associated with PSA progression (P = 0.10). Dividing patients according to whether they received immediate ADT or not, tissue CgA was associated with a shorter time to PSA progression in ADT-treated patients (hazard ratios (HR) 1.96, 95% confidence interval (CI): 1.37-2.81, P = 0.0001), but failed to be associated in those who did not (HR 0.87, 95% CI: 0.58-1.30, P = 0.49), interaction test P = 0.007. Conversely the survival effect of tissue CgA was not modified by ADT (interaction test, P = 0.41).

CONCLUSIONS

Tissue CgA expression, evaluated in prostate cancer needle biopsies at diagnosis, is an independent prognostic factor of survival in prostate cancer patients. The negative influence of NE differentiation on time to progression confined in ADT-treated patients suggests a role of NE differentiation in predicting endocrine resistance that deserves validation.

Evaluation of neuroendocrine markers in renal cell carcinoma

Background

The purpose of the study was to examine serotonin, CD56, neurone-specific enolase (NSE), chromogranin A and synaptophysin by immunohistochemistry in renal cell carcinomas (RCCs) with special emphasis on patient outcome.

Methods

We studied 152 patients with primary RCCs who underwent surgery for the removal of kidney tumours between 1990 and 1999. The mean follow-up was 90 months. The expression of neuroendocrine (NE) markers was determined by immunohistochemical staining using commercially available monoclonal antibodies. Results were correlated with patient age, clinical stage, Fuhrman grade and patient outcome.

Results

Eight percent of tumours were positive for serotonin, 18% for CD56 and 48% for NSE. Chromogranin A immunostaining was negative and only 1% of the tumours were synaptophysin immunopositive. The NSE immunopositivity was more common in clear cell RCCs than in other subtypes (p = 0.01). The other NE markers did not show any association with the histological subtype. Tumours with an immunopositivity for serotonin had a longer RCC-specific survival and tumours with an immunopositivity for CD56 and NSE had a shorter RCC-specific survival but the difference was not significant. There was no relationship between stage or Fuhrman grade and immunoreactivity for serotonin, CD56 and NSE.

Conclusions

Serotonin, CD56 and NSE but not synaptophysin and chromogranin A are expressed in RCCs. However, the prognostic potential of these markers remains obscure.

Selective expression of CD44, a putative prostate cancer stem cell marker, in neuroendocrine tumor cells of human prostate cancer

BACKGROUND

Hormonal therapy is effective for advanced prostate cancer (PC) but the disease often recurs and becomes hormone-refractory. It is hypothesized that a subpopulation of cancer cells, that is, cancer stem cells (CSCs), survives hormonal therapy and leads to tumor recurrence. CD44 expression was shown to identify tumor cells with CSC features. PC contains secretory type epithelial cells and a minor population of neuroendocrine cells. Neuroendocrine cells do not express androgen receptor and are quiescent, features associated with CSCs. The purpose of the study was to determine the expression of CD44 in human PC and its relationship to neuroendocrine tumor cells.

METHODS

Immunohistochemistry and immunofluorescence were performed to study CD44 expression in PC cell lines, single cells from fresh PC tissue and archival tissue sections of PC. We then determined if CD44+ cells represent neuroendocrine tumor cells.

RESULTS

In human PC cell lines, expression of CD44 is associated with cells of NE phenotype. In human PC tissues, NE tumor cells are virtually all positive for CD44 and CD44+ cells, excluding lymphocytes, are all NE tumor cells.

CONCLUSIONS

Selective expression of the stem cell-associated marker CD44 in NE tumor cells of PC, in combination with their other known features, further supports the significance of such cells in therapy resistance and tumor recurrence.

Serotonin used as prognostic marker of urological tumors

INTRODUCTION

In regard to therapy and prognosis of urological tumors, specific tumor markers are lacking especially in renal and urinary bladder carcinoma. Our study examines the relevance of serum serotonin levels to urinary bladder, prostate, renal, and testicular carcinoma when it comes to prognosis and occurrence of these oncological conditions.

MATERIALS AND METHODS

Serotonin levels were obtained in 109 patients presenting with urothelial carcinoma to the urinary bladder, adenocarcinoma of the prostate and renal cell carcinoma, as well as presenting with seminomatous and non-seminomatous testicular tumors. All of these conditions varied in grades and metastases. Serum levels were drawn between 7 and 8 a.m. exclusively in order to avoid circadian changes.

RESULTS

Serotonin levels in urothelial carcinoma appeared within pathological range in correlation with tumor stage, life expectancy, and statistical significant with distant metastases. In prostate carcinoma, serotonin levels showed a tendency with organ exceeding growth, Grading/Gleason Score, PSA values >100 ng/ml, and the presence of distant metastases. In renal cell carcinoma, serotonin levels were decreased in patients with lymph node and distant metastases; there was no significant correlation with extent of infiltration. In regard to testicular carcinoma, decreased serotonin levels were merely noted in mixed tumors and the one extragonadal seminoma. Otherwise there was no correlation observed with stage and grade as well as with common tumor markers (AFP/betaHCG).

CONCLUSION

Serotonin levels are suitable for prognostic evaluation of urothelial carcinoma in the urinary bladder, adenocarcinoma of the prostate, and renal cell carcinoma, especially taking into account the lab cost of 25<euro> per test.

Differential effects of prostate cancer therapeutics on neuroendocrine transdifferentiation

Androgen ablation therapy is widely used for the treatment of advanced prostate cancer. However, the effectiveness of this intervention strategy is generally short-lived as the disease ultimately progresses to a hormone-refractory state. In recent years, it has become clear that even in antiandrogen-resistant cancers the androgen receptor (AR) signaling axis is intact and is required for prostate cancer growth. Thus, there is a heightened interest in developing small molecules that function in part by down-regulating AR expression in tumors. Paradoxically, AR expression has been shown to be important in preventing the transdifferentiation of epithelial prostate cancer cells toward a neuroendocrine phenotype associated with tumor progression. Consequently, we have evaluated the relative effect of prostate cancer therapeutics that function in part by depleting AR levels on neuroendocrine differentiation in established cellular models of prostate cancer. These studies reveal that although histone deacetylase inhibitors can down-regulate AR expression they increase the expression of neuroendocrine markers and alter cellular morphology. Inhibition of AR signaling using classic AR antagonists or small interfering RNA-mediated AR ablation induces incomplete neuroendocrine differentiation. Importantly, the Hsp90 inhibitor geldanamycin effectively down-regulates AR expression while having no effect on neuroendocrine differentiation. Taken together, these data show that the phenotypic responses to pharmacologic agents used in the clinic to prevent the progression of prostate cancer are not equivalent, a finding of significant therapeutic importance.

Pro-neural transcription factors as cancer markers

BACKGROUND

The aberrant transcription in cancer of genes normally associated with embryonic tissue differentiation at various organ sites may be a hallmark of tumour progression. For example, neuroendocrine differentiation is found more commonly in cancers destined to progress, including prostate and lung. We sought to identify proteins which are involved in neuroendocrine differentiation and differentially expressed in aggressive/metastatic tumours.

RESULTS

Expression arrays were used to identify up-regulated transcripts in a neuroendocrine (NE) transgenic mouse model of prostate cancer. Amongst these were several genes normally expressed in neural tissues, including the pro-neural transcription factors Ascl1 and Hes6. Using quantitative RT-PCR and immuno-histochemistry we showed that these same genes were highly expressed in castrate resistant, metastatic LNCaP cell-lines. Finally we performed a meta-analysis on expression array datasets from human clinical material. The expression of these pro-neural transcripts effectively segregates metastatic from localised prostate cancer and benign tissue as well as sub-clustering a variety of other human cancers.

CONCLUSION

By focussing on transcription factors known to drive normal tissue development and comparing expression signatures for normal and malignant mouse tissues we have identified two transcription factors, Ascl1 and Hes6, which appear effective markers for an aggressive phenotype in all prostate models and tissues examined. We suggest that the aberrant initiation of differentiation programs may confer a selective advantage on cells in all contexts and this approach to identify biomarkers therefore has the potential to uncover proteins equally applicable to pre-clinical and clinical cancer biology.

The impact of diet and micronutrient supplements on the expression of neuroendocrine markers in murine Lady transgenic prostate

BACKGROUND

Neuroendocrine (NE) differentiation (NED) in prostate cancer (PCa) is associated with morbidity and death; however, the underlying cause(s) promoting NED in PCa have yet to be determined. In this study, we examined the effect of both diet and micronutrient supplementation on the expression of NE markers using the Lady (12T-10) transgenic model of PCa. Lady (12T-10) transgenic animals develop advanced adenocarcinoma with NE characteristics that exhibits metastases in approximately 80% of cases. In this model a high fat diet has been shown to increase the severity of disease, while the use of micronutrients can inhibit this progression.

METHODS

In this study we used immunohistochemical analysis to determine expression of the NE markers: chromogranin A (CgA), neuron-specific enolase (NSE), bombesin, parathyroid hormone-related peptide (PTHrP), neurotensin and serotonin in prostates of PCa-bearing Lady (12T-10) mice.

RESULTS

High fat diet was correlated with significantly elevated expression of CgA and serotonin in prostate tissue of Lady (12T-10) mice. Addition of micronutrients to the control and high fat diet reproducibly elevated PTHrP and bombesin expression and suppressed NSE expression, while prostate tissue from the control diet supplemented with micronutrients exhibited significantly lower numbers of calcitonin- and neurotensin-positive cells.

CONCLUSIONS

These results highlight the importance of dietary control in management of disease and identify differential changes in NE marker expression, which may be diagnostically viable in monitoring the impact of therapies on disease status.

NeuroD1 Expression in Human Prostate Cancer: Can It Contribute to Neuroendocrine Differentiation Comprehension?

OBJECTIVES

Neuroendocrine differentiation is a common feature of prostate cancer (pCA). NeuroD1 is a neuronal transcription factor able to convert epithelial cells into neurons. The aim of the study is to investigate NeuroD1 expression and compare it with chromogranin-A, synaptophysin, and CD56 staining in human prostate cell lines and surgical specimens.

METHODS

We detected NeuroD1 gene expression, by duplex reverse transcriptase-polymerase chain reaction, in primary human prostate fibroblasts, in EPN, LNCaP, DU145, and PC3 cell lines before and after cAMP exposure, in 6 BPH and 11 pCA samples. Thereafter 166 paraffin sections from normal and neoplastic prostates were stained with NeuroD1, chromogranin-A, synaptophysin, and CD56 antibodies. The relationships between chromogranin-A and NeuroD1 and clinicopathologic parameters were evaluated by multivariate logistic regression analysis.

RESULTS

NeuroD1 is inactive in baseline prostate cell lines and BPHs, whereas it is actively expressed in cAMP-treated EPN, PC3, and DU145 cells. In our surgical series, positive chromogranin-A, synaptophysin, CD56, and NeuroD1 staining was detected in 26.5%, 4.3%, 3.1%, and 35.5%, respectively (difference between chromogranin-A and NeuroD1: p<0.05). The multivariate analysis showed a strong association between chromogranin-A and microscopic perineural invasion (OR: 2.49; 95%CI, 0.85-7.32; p=0.097) and a high primary Gleason score (OR: 1.96; 95%CI, 1.14-3.39; p=0.015), whereas NeuroD1 expression strictly correlated to microscopic perineural invasion (OR: 2.97; 95%CI, 1.05-8.41; p=0.04).

CONCLUSIONS

Expression of NeuroD1 versus chromogranin-A is more frequent in pCA, and correlates to increased indicators of malignancy in moderately to poorly differentiated pCA, and could be involved in the pathophysiology of the neuroendocrine differentiation of pCA.

EGF prevents the neuroendocrine differentiation of LNCaP cells induced by serum deprivation: the modulator role of PI3K/Akt

The primary focus of this investigation was to study the relationship between neuroendocrine (NE) differentiation and epidermal growth factor (EGF) because both have been implicated in the progression of prostate cancer. For this purpose, we used gefitinib and trastuzumab, which are inhibitors of EGF receptor (EGFR) and ErbB2, respectively. EGF prevents NE differentiation induced by androgen depletion. This effect is prevented by gefitinib, which blocks the activation of EGFR and ErbB2, stimulation of mitogen-activated protein kinase (MAPK), and cell proliferation induced by EGF. Conversely, trastuzumab does not inhibit the effect of EGF on EGFR phosphorylation, MAPK activity, cell proliferation, and NE differentiation, although it reduces ErbB2 levels specifically, suggesting that ErbB2 is not necessary to inhibit NE differentiation. Prevention of NE differentiation by EGF is mediated by a MAPK-dependent mechanism and requires constitutive Akt activation. The abrogation of the PI3K/Akt pathway changes the role of EGF from inhibitor to inductor of NE differentiation. We show that EGFR tyrosine kinase, MAPK, and PI3K inhibitors inhibit the cell proliferation stimulated by EGF but induce the acquisition of NE phenotype. Altogether, the present data should be borne in mind when designing new clinical schedules for the treatment of prostate cancer, including the use of ErbB receptors and associated signaling pathway inhibitors.

Does small-cell phenotype predict the natural history of prostate cancer? A case study in disease behavior

BACKGROUND

A 52-year-old man presented to his urologist with hematuria and symptoms of frequency and incomplete voiding. The patient received antibiotics without symptom resolution. His prostate-specific antigen (PSA) level was 6.6 ng/ml and digital rectal examination revealed a normal-sized firm prostate gland. Biopsy obtained by transurethral resection revealed poorly differentiated Gleason 9 adenocarcinoma of the prostate with small-cell/neuroendocrine features. Pure small-cell cancer or poorly differentiated prostate cancer may secrete little or no PSA. One should be alerted to this phenotype in a patient with large volume disease on biopsy or examination and a low PSA or PSA not in proportion to tumor burden.

INVESTIGATIONS

Digital rectal examination, laboratory tests, cystoscopy, prostatic chips obtained from transurethral resection, prostate biopsy, bone scan, CT scan of the chest, abdomen and pelvis.

DIAGNOSIS

Poorly differentiated Gleason 9 adenocarcinoma of the prostate with small-cell/neuroendocrine features.

MANAGEMENT

Transurethral resection, androgen blockade with a gonadotropin-releasing hormone analog and antiandrogen flutamide, oral bicalutamide, docetaxel and oral estramustine. Total pelvic exenteration with ileal conduit urinary diversion and permanent end-colostomy formation, percutaneous nephrostomy placement, cisplatin combined with etoposide.

Chromogranin A expression in patients with hormone naïve prostate cancer predicts the development of hormone refractory disease

PURPOSE

We assessed chromogranin A as a tissue biomarker in prostate needle biopsies or as a plasma biomarker, a risk factor for hormone refractory prostate cancer.

MATERIALS AND METHODS

A total of 211 patients with newly diagnosed prostate cancer treated with luteinizing hormone releasing hormone analogues constituted the study cohort. Univariate and multivariate Cox regression analyses were used to assess the predictive role of tissue and plasma chromogranin A expression.

RESULTS

Chromogranin A expression in less than 30% or in 30% or more tumor cells was significantly associated with a shorter time to hormone refractory disease on univariate analysis (HR 2.0, 95% CI 1.3-3.1 and HR 6.0, 95% CI 2.7-12.9), or on multivariate analysis after adjusting for Gleason score, serum prostate specific antigen and disease stage (HR 1.7, 95% CI 1.0-2.8 and HR 3.9, 95% CI 1.7-9.0), respectively. Plasma chromogranin A measured at baseline (HR 3.0, 95% CI 1.8-5.2), and after 1 year (HR 5.8, 95% CI 3.1-10.1) and 2 years (HR 3.5, 95% CI 1.6-7.6), was predictive of hormone refractory risk confirming the tissue results. Plasma as well as tissue chromogranin A expression negatively correlated with overall survival.

CONCLUSIONS

Chromogranin A expression in prostate cancer biopsies is an independent predictive factor of hormone refractory disease in patients with newly diagnosed prostate cancer on early androgen deprivation therapy. Plasma chromogranin A is also a reliable predictive marker and the predictive significance is maintained over time. These results deserve validation in another data set.

Androgen-independent growth and tumorigenesis of prostate cancer cells are enhanced by the presence of PKA-differentiated neuroendocrine cells

The neuroendocrine status of prostatic adenocarcinomas is considered a prognostic indicator for development of aggressive, androgen-independent disease. Neuroendocrine-like cells are thought to function by providing growth and survival signals to surrounding tumor cells, particularly following androgen ablation therapy. To test this hypothesis directly, LNCaP cells were engineered to inducibly express a constitutively activated form of the cyclic AMP-dependent protein kinase A catalytic subunit (caPKA), which was previously found upon transient transfection to be sufficient for acquisition of neuroendocrine-like characteristics and loss of mitotic activity. Clonal cells that inducibly expressed caPKA enhanced the growth of prostate tumor cells in anchorage-dependent and anchorage-independent in vitro assays as well as the growth of prostate tumor xenografts in vivo, with the greatest effects seen under conditions of androgen deprivation. These results suggest that neuroendocrine-like cells of prostatic tumors have the potential to enhance androgen-independent tumor growth in a paracrine manner, thereby contributing to progression of the disease.

Molecular staging of prostate cancer in the year 2007

Numerous attempts towards improving patient management by molecular staging have been fruitless so far. No single molecular parameter is routinely analyzed in prostate cancer tissue. This may be partly due to genuine properties of prostate cancer that may make this tumor a difficult target. Furthermore, inherent logistical problems result in a shortage of prostate cancer tissue for research purposes. For the future, it can be hoped that the availability of more powerful molecular techniques in combination with better tissue archives will allow more rapid progress. Powerful DNA array and proteomics methods allow the systematic analysis of virtually all genes of a cancer on the DNA, RNA, and protein level. Although such approaches are sometimes labeled as "fishing expeditions," it cannot be totally disregarded that the simultaneous analysis of all genes has a high likelihood of identifying significant new information. In future, one of the major scientific challenges will be the validation of several potential biomarkers in large enough and clinically well-characterized patient cohorts. In particular, studies on needle core biopsies and hormone refractory cancers are imperatively needed for investigating the natural history of the disease or to discover potential predictive markers for radiation therapy and new therapeutic target genes to answer the clinically most important questions for optimal clinical decision making in prostate cancer patients: which patients will not require local therapy? If local therapy is needed, what is the treatment of choice? What medications should be given if metastases are present?

An immunohistochemical study of chromogranin A and human epidermal growth factor-2 expression using initial prostate biopsy specimens from patients with bone metastatic prostate cancer

OBJECTIVES

To investigate, using prostate needle-biopsy specimens at diagnosis from patients with bone metastatic prostate cancer, whether the relationship between neuroendocrine (NE) cell differentiation and human epidermal growth factor-2 (HER-2) expression is a prognostic factor for outcome.

PATIENTS AND METHODS

The study included 50 patients diagnosed as having bone metastatic prostate cancer between January 1998 and December 2001. We tested for NE cell differentiation by using immunohistochemical (IHC) staining for chromogranin A (CgA), and for HER-2, using a commercial test for IHC staining.

RESULTS

Eleven patients (22%) were positive for CgA; there was a significant difference in the time to recurrence (P = 0.025) but no significant differences in cause-specific survival rate or survival rate after recurrence. In all, 21 patients (42%) were positive for HER-2; the cause-specific survival rate, time to recurrence and survival rate after recurrence were all significantly more favourable in the HER-2-negative group (P = 0.008, 0.049 and 0.025, respectively). In the 49 patients for whom both factors could be determined, there was no significant correlation between CgA and HER-2 positivity.

CONCLUSIONS

NE cell differentiation of the primary tumour in patients with bone metastatic prostate cancer does not reflect the prognosis, whereas HER-2 overexpression is a prognostic factor for an unfavourable outcome. These results suggest that NE cell differentiation is not induced by HER-2.

Aberrant neuropeptide Y and macrophage inhibitory cytokine-1 expression are early events in prostate cancer development and are associated with poor prognosis

Studies to elucidate dysregulated gene expression patterns in premalignant prostate lesions have identified several candidate genes with the potential to be targeted to prevent the development and progression of prostate cancer and act as biomarkers of early disease. Herein, we explored the importance of two proteins, neuropeptide Y (NPY) and macrophage inhibitory cytokine-1 (MIC-1), as biomarkers of preinvasive prostate disease and investigated the relationship of expression to biochemical recurrence following treatment for localized prostate cancer. NPY and MIC-1 protein expression was determined by immunohistochemistry on tissue microarrays containing 1,626 cores of benign, low-grade prostatic intraepithelial neoplasia (PIN), high-grade PIN (HGPIN), and prostate cancer tissue from 243 radical prostatectomy patients. Both NPY and MIC-1 showed higher proportional immunostaining in HGPIN and prostate cancer compared with benign epithelium (P < 0.0001). NPY and MIC-1 immunostaining was higher in low-grade PIN compared with other benign tissues (both P < 0.0001) and was equivalent to immunostaining in HGPIN. NPY immunostaining of prostate cancer was independently associated with relapse, after adjusting for traditional prognostic factors, as a categorical variable in 20% intervals (P = 0.0449-0.0103) and as a continuous variable (P = 0.0017). Low MIC-1 immunostaining (20% categories) was associated with pathologic stage >2C after adjusting for predictors of pathologic stage (P = 0.3894-0.0176). This is the first study to show that altered NPY and MIC-1 expression are significantly associated with prostate cancer progression and suggests that these molecules be developed further as biomarkers in the management of prostate disease.

Immunohistochemical characterization of neuroendocrine cells in prostate cancer

BACKGROUND

Neuroendocrine (NE) cells increase in high grade/stage prostate cancer (PC) and may contribute to androgen-independent cancer. Their immunohistochemical phenotype has not been studied in detail and conflicting results have been reported.

METHODS

PC tissue was stained immunohistochemically for luminal secretory cell-associated cytokeratin, basal cell markers, ki-67, androgen receptor (AR), PSA, prostate acid phosphatase (PAP), and alpha-methylacyl coenzyme A racemase (AMACR).

RESULTS

The NE cells are positive for AE1/AE3, Cam 5.2, and negative for basal cell markers. They are negative for AR, PSA, and Ki-67 but positive for PAP. The benign NE cells are negative for AMACR while the malignant NE cells are positive for AMACR.

CONCLUSIONS

NE cells of PC constitute a unique subset of cancer cells, which have a unique immunohistochemical profile. They do not express AR, consistent with their resistance to hormonal therapy. They are post-mitotic cells but are malignant and part of the tumor.

Neuroendocrine differentiation in prostate cancer: a sheep in wolf's clothing?

Neuroendocrine differentiation of the prostate is often associated with a dismal prognosis. Whilst it is relatively rare compared with other forms of prostate cancer, it nevertheless remains difficult to treat these cancers effectively and to maintain a durable response. Research aimed at understanding the complexity of neuroendocrine differentiation of the prostate has been conducted for some time. The cells involved in this process secrete a variety of factors that can influence growth patterns and regulatory pathways. Many of these factors can be monitored serologically, but the relationship between the biology of the tumor and clinical response is often discordant. This review outlines the difficulties in treating this disease, both at the time of diagnosis and in the metastatic setting, and focuses on an area of research that remains challenging to both the researcher and clinician.

Prognostic significance of neuroendocrine expression in lymph node-positive prostate cancer

OBJECTIVES

To evaluate the expression of chromogranin A, a marker for neuroendocrine (NE) differentiation, in patients with lymph node-positive prostate cancer to determine its prognostic significance. NE cells are involved in cellular growth and differentiation in both normal and pathologic conditions of the prostate.

METHODS

We reviewed the data of 140 patients with lymph node-positive prostate adenocarcinoma treated with radical prostatectomy and pelvic lymphadenectomy. The median follow-up was 10.9 years (range 0.8 to 19.7). Immunohistochemical staining for chromogranin A was evaluated in areas of benign epithelium, primary prostate cancer, and lymph node metastasis. The association between chromogranin A expression and the clinical and pathologic factors (preoperative serum prostate-specific antigen and prostatectomy Gleason score and stage) and clinical outcomes, including overall and recurrence-free survival, was evaluated.

RESULTS

Staining was positive in 86% of benign areas, 61% of primary cancer specimens, and 12% of lymph node deposits. The preoperative serum prostate-specific antigen level and pathologic stage and grade of the primary tumor did not show any statistically significant correlation with NE staining in any of the areas. Only NE expression in the primary tumor was associated with clinical recurrence, with a 10-year recurrence-free survival rate for those with less than 5% staining of 67% compared with 35% for those with 5% staining or greater (P = 0.03). Furthermore, after adjusting for age, greater NE expression in the primary tumor (relative risk 2.15, P = 0.02) and lymph node deposit (relative risk 2.03, P = 0.03) was associated with poorer overall survival.

CONCLUSIONS

NE expression in the primary tumor and lymph node metastasis of patients with node-positive prostate cancer may provide additional prognostic stratification.