Unusual and Underappreciated: Small Cell Carcinoma of the Prostate

Organoids with cancer stem cell-like properties secrete exosomes and HSP90 in a 3D nanoenvironment

Ability to form cellular aggregations such as tumorspheres and spheroids have been used as a morphological marker of malignant cancer cells and in particular cancer stem cells (CSC). However, the common definition of the types of cellular aggregation formed by cancer cells has not been available. We examined morphologies of 67 cell lines cultured on three dimensional morphology enhancing NanoCulture Plates (NCP) and classified the types of cellular aggregates that form. Among the 67 cell lines, 49 cell lines formed spheres or spheroids, 8 cell lines formed grape-like aggregation (GLA), 8 cell lines formed other types of aggregation, and 3 cell lines formed monolayer sheets. Seven GLA-forming cell lines were derived from adenocarcinoma among the 8 lines. A neuroendocrine adenocarcinoma cell line PC-3 formed asymmetric GLA with ductal structures on the NCPs and rapidly growing asymmetric tumors that metastasized to lymph nodes in immunocompromised mice. In contrast, another adenocarcinoma cell line DU-145 formed spheroids in vitro and spheroid-like tumors in vivo that did not metastasize to lymph nodes until day 50 after transplantation. Culture in the 3D nanoenvironment and in a defined stem cell medium enabled the neuroendocrine adenocarcinoma cells to form slowly growing large organoids that expressed multiple stem cell markers, neuroendocrine markers, intercellular adhesion molecules, and oncogenes in vitro. In contrast, the more commonly used 2D serum-contained environment reduced intercellular adhesion and induced mesenchymal transition and promoted rapid growth of the cells. In addition, the 3D stemness nanoenvironment promoted secretion of HSP90 and EpCAM-exosomes, a marker of CSC phenotype, from the neuroendocrine organoids. These findings indicate that the NCP-based 3D environment enables cells to form stem cell tumoroids with multipotency and model more accurately the in vivo tumor status at the levels of morphology and gene expression.

Targeting the MYCN-PARP-DNA Damage Response Pathway in Neuroendocrine Prostate Cancer

Purpose: We investigated MYCN-regulated molecular pathways in castration-resistant prostate cancer (CRPC) classified by morphologic criteria as adenocarcinoma or neuroendocrine to extend the molecular phenotype, establish driver pathways, and identify novel approaches to combination therapy for neuroendocrine prostate cancer (NEPC).Experimental Design and Results: Using comparative bioinformatics analyses of CRPC-Adeno and CRPC-Neuro RNA sequence data from public data sets and a panel of 28 PDX models, we identified a MYCN-PARP-DNA damage response (DDR) pathway that is enriched in CRPC with neuroendocrine differentiation (NED) and CRPC-Neuro. ChIP-PCR assay revealed that N-MYC transcriptionally activates PARP1, PARP2, BRCA1, RMI2, and TOPBP1 through binding to the promoters of these genes. MYCN or PARP1 gene knockdown significantly reduced the expression of MYCN-PARP-DDR pathway genes and NED markers, and inhibition with MYCNsi and/or PARPsi, BRCA1si, or RMI2si significantly suppressed malignant activities, including cell viability, colony formation, and cell migration, in C4-2b4 and NCI-H660 cells. Targeting this pathway with AURKA inhibitor PHA739358 and PARP inhibitor olaparib generated therapeutic effects similar to those of gene knockdown in vitro and significantly suppressed tumor growth in both C4-2b4 and MDACC PDX144-13C subcutaneous models in vivoConclusions: Our results identify a novel MYCN-PARP-DDR pathway that is driven by N-MYC in a subset of CRPC-Adeno and in NEPC. Targeting this pathway using in vitro and in vivo CRPC-Adeno and CRPC-Neuro models demonstrated a novel therapeutic strategy for NEPC. Further investigation of N-MYC-regulated DDR gene targets and the biological and clinical significance of MYCN-PARP-DDR signaling will more fully elucidate the importance of the MYCN-PARP-DDR signaling pathway in the development and maintenance of NEPC. Clin Cancer Res; 24(3); 696-707. ©2017 AACR.

A Case of Small Cell Carcinoma of the Prostate and Review of the Literature

Aim and background

Small cell carcinoma of the prostate (SCCP) is a relatively rare entity, an aggressive tumor with a tendency to metastasize early. There is no standard chemotherapy regimen for SCCP. We report the case of a 67-year-old man with an initial diagnosis of prostate adenocarcinoma with bone metastases who subsequently developed a small cell carcinoma of the prostate with liver metastases.

Methods and study design

A review of this case and of the current literature was done with a view to highlighting the ideal approach to such an unusual tumor.

Results and conclusion

The patient was treated with carboplatin and etoposide and after 3 cycles achieved a good response. Unfortunately he developed massive pulmonary embolism which impeded the continuation of treatment and caused his death. By reviewing the literature we found there is no standard of care and new targeted therapies have failed to prove any benefit so far. It is mandatory to persevere in planning trials and exploring new drugs to improve the outcome of patients with SC-C P. It might also be worth creating a register for SCCP where data can be collected to coordinate the management of these patients and to establish better connections among cancer centers.

Benefit of rebiopsy for deciding treatment strategy in rectal cancer: A case report

Rebiopsy is considered an option for specific types of cancer, such as breast, non-small cell lung, and prostate cancer, in clinical trials and in practice. The benefit of rebiopsy comes from the selection of a new treatment strategy based on the genetic profile of the cells, which may reflect the development of drug resistance or hormonal changes. For colorectal cancer, the presence of different genomic mutations between the primary tumor and its metastases is rare, and rebiopsy is therefore not generally performed. The present study reports the case of a 68-year-old man who was initially diagnosed with metastatic adenocarcinoma from a primary colorectal cancer, but was subsequently rediagnosed with metastatic neuroendocrine carcinoma based on the pathological rebiopsy results. The patient responded well to cisplatin and etoposide treatment, after not responding to initial FOLFOX treatment. In this case, rebiopsy resulted in a change in treatment regimen and improved the patient's quality of life and his long-term survival. This case indicates that, when a colorectal cancer patient is unresponsive to standard treatment, it may be beneficial for the clinician to suspect an atypical histological type, and to consider rebiopsy.

Targeting androgen-independent pathways: new chances for patients with prostate cancer?

Androgen deprivation therapy (ADT) is the mainstay treatment for advanced prostate cancer (PC). Most patients eventually progress to a condition known as castration-resistant prostate cancer (CRPC), characterized by lack of response to ADT. Although new androgen receptor signaling (ARS) inhibitors and chemotherapeutic agents have been introduced to overcome resistance to ADT, many patients progress because of primary or acquired resistance to these agents. This comprehensive review aims at exploring the mechanisms of resistance and progression of PC, with specific focus on alterations which lead to the activation of androgen receptor (AR)-independent pathways of survival. Our work integrates available clinical and preclinical data on agents which target these pathways, assessing their potential clinical implication in specific settings of patients. Given the rising interest of the scientific community in cancer immunotherapy strategies, further attention is dedicated to the role of immune evasion in PC.

Severe Cushing's syndrome due to small cell prostate carcinoma: a case and review of literature

Cushing's syndrome (CS) due to ectopic adrenocorticotrophic hormone (ACTH) is associated with a variety of tumours most of which arise in the thorax or abdomen. Prostate carcinoma is a rare but important cause of rapidly progressive CS. To report a case of severe CS due to ACTH production from prostate neuroendocrine carcinoma and summarise previous published cases. A 71-year-old male presented with profound hypokalaemia, oedema and new onset hypertension. The patient reported two weeks of weight gain, muscle weakness, labile mood and insomnia. CS due to ectopic ACTH production was confirmed with failure to suppress cortisol levels following low- and high-dose dexamethasone suppression tests in the presence of a markedly elevated ACTH and a normal pituitary MRI. Computed tomography demonstrated an enlarged prostate with features of malignancy, confirmed by MRI. Subsequent prostatic biopsy confirmed neuroendocrine carcinoma of small cell type and conventional adenocarcinoma of the prostate. Adrenal steroidogenesis blockade was commenced using ketoconazole and metyrapone. Complete biochemical control of CS and evidence of disease regression on imaging occurred after four cycles of chemotherapy with carboplatin and etoposide. By the sixth cycle, the patient demonstrated radiological progression followed by recurrence of CS and died nine months after initial presentation. Prostate neuroendocrine carcinoma is a rare cause of CS that can be rapidly fatal, and early aggressive treatment of the CS is important. In CS where the cause of EAS is unable to be identified, a pelvic source should be considered and imaging of the pelvis carefully reviewed.

Small Cell Carcinoma of the Prostate: A Case Report and Brief Review of the Literature

Small cell carcinoma of the prostate (SCCP) is a rare disorder. We present here a case of SCCP exhibiting multiple unique clinical findings, demonstrating the variability of SCCP at presentation.

The Missing Link in the Diagnostic Pathway of Prostate Cancer

Prostate cancer is one of the most common cancers in the Western world. It is among the leading causes of cancer related death. While its incidence and survival increased significantly during the last few decades in Denmark, the mortality rate did not change for patients younger than 80 year old. Development of new techniques, such as multiparametric MRI, helps to increase the accuracy of diagnosis. However, a missing link in the diagnostic pathway may result in mistreatment if an acinar adenocarcinoma of prostate is transformed into a neuroendocrine phenotype such as small cell carcinoma.

Pure small cell carcinoma of the prostate preceded by acute zonal occult outer retinopathy: A case report

INTRODUCTION

Pure small cell prostate cancer (SCPC) cases are very rare. Acute zonal occult outer retinopathy (AZOOR) has been described as a non-neoplastic retinopathy. We report the first case of pure SCPC preceded by AZOOR in the literature.

CASE REPORT

A 59year old gentleman presented with an obstructed infected urinary system. He had a diagnosis of AZOOR 6 months ago that was investigated with full body imaging without any suspicious findings. However, the most recent CT findings demonstrated extensive disease dissemination. The patient underwent rigid cystoscopy and resection that confirmed a diagnosis of pure SCPC.

DISCUSSION

AZOOR is a clinical syndrome of photopsia and rapid zonal field loss. The exact aetiology remains unknown and its association with malignancy remains contentious. Paraneoplastic manifestations of unexplained visual loss in SCPC are rare with only 2 cases reported in the literature. There are no cases demonstrating an association between AZOOR and SCPC.

CONCLUSION

Pure SCPC is an aggressive malignancy with most cases presenting with extensive disease dissemination on diagnosis. Early detection has a role in improving prognosis but is challenging. Further research is required to establish a standard treatment protocol.

Rapid progression of mixed neuroendocrine carcinoma-acinar adenocarcinoma of the prostate: A case report

The current study presents the case of a 78-year-old male with mixed neuroendocrine (NE) carcinoma-acinar adenocarcinoma of the prostate. The patient received endocrine therapy (maximal androgen blockade) after the initial diagnosis resulting in a significant decrease in serum prostate-specific antigen (PSA) level. The patient underwent transurethral resection of the prostate after 6 months of androgen-deprivation therapy for extraordinarily salient difficulty in urination, and histopathology demonstrated mixed NE carcinoma-acinar adenocarcinoma once again. The NE prostate cancer progressed rapidly even though the serum PSA was controlled at a low level on account of the endocrine therapy. Previous treatment protocols were replaced by combined chemotherapy and endocrine therapy, and the patient responded well. The patient's serum PSA remained at a low level, however, urethral dilatation for acute urinary retention was required again 5 months later and the lower urinary tract symptoms became increasingly evident. The patient eventually died of cachexia.. These findings indicate that mixed NE carcinoma-acinar adenocarcinoma has a higher degree of malignancy and that endocrine therapy for prostate cancer has a propensity to facilitate progression of this tumor.

Genomic predictors for treatment of late stage prostate cancer

In spite of the development of new treatments for late stage prostate cancer, significant challenges persist to match individuals with effective targeted therapies. Genomic classification using high-throughput sequencing technologies has the potential to achieve this goal and make precision medicine a reality in the management of men with castrate-resistant prostate cancer. This chapter reviews some of the most recent studies that have resulted in significant progress in determining the landscape of somatic genomic alterations in this cohort and, more importantly, have provided clinically actionable information that could guide treatment decisions. This chapter reviews the current understanding of common alterations such as alterations of the androgen receptor and PTEN pathway, as well as ETS gene fusions and the growing importance of PARP inhibition. It also reviews recent studies that characterize the evolution to neuroendocrine tumors, which is becoming an increasingly important clinical problem. Finally, this chapter reviews recent innovative studies that characterize the compelling evolutionary history of lethal prostate cancer evidenced by polyclonal seeding and interclonal cooperation between metastasis and the importance of tumor clone dynamics measured serially in response to treatment. The genomic landscape of late stage prostate cancer is becoming better defined, and the prospect for assigning clinically actionable data to inform rationale treatment for individuals with this disease is becoming a reality.

[Management of neuroendocrine prostate carcinoma: Literature review]

Neuroendocrine prostate carcinoma is a rare entity causing both diagnostic and therapeutic issues. There are basically four histological forms (adenocarcinoma with neuroendocrine differentiation, carcinoid tumors, small cell neuroendocrine carcinomas, large cell neuroendocrine carcinomas), which can be pure or mixed associated with prostatic carcinoma. There is no consensus on the management or the prognosis of these various tumor subtypes. We conducted a literature review aiming to determine the potential therapeutic implications.

An Unusual Etiology of Urinary Retention - Small Cell Prostate Carcinoma

We report the case of a 63-year-old male who presented with painless gross hematuria and urinary retention. Pathology obtained from transurethral resection of the prostate revealed pure small cell carcinoma of the prostate. Metastatic evaluation confirmed stage IV disease with lymphatic and hepatic metastasis. Despite aggressive systemic chemotherapy, the patient succumbed to his disease eleven months after initial diagnosis. Small cell carcinoma is an aggressive variant of prostate cancer that often presents late in the clinical course. We review the literature and discuss the clinical features associated with this rare subset of prostate cancer.

PCA3 and TMPRSS2-ERG gene fusions as diagnostic biomarkers for prostate cancer

The incidence of prostate cancer (PCa) is rising steadily among males in many countries. Serum prostate-specific antigen (PSA) is widely applied to clinical diagnosis and screening of PCa. However, the so-called grey area of PSA levels 4.0-10.0 ng/mL has a low specificity of 25-40% resulting in a high rate of negative biopsy and overtreatment. So in order to treat PCa patients in early stage, there is an urgent need for new biomarkers in PCa diagnosis. The PCA3 gene, a non-coding RNA (ncRNA) that is highly expressed in prostate cancer (PCa) cells, has been identified as a molecular biomarkers to detect PCa, of which PCA3 has already under clinical application. PCA3 is strongly overexpressed in malignant prostate tissue compared to benign or normal adjacent one. Newly, PCA3 is considered to be a promising biomarker in clinical diagnosis and targeted therapy. The diagnostic significance of PCA3, however, is awaiting further researches. Moreover, it has been demonstrated recently that TMPRSS2-ERG gene fusion is identified as the predominant genetic change in patients diagnosed with PCa. Recent study revealed that combination of the PCA3 and TMPRSS2-ERG gene fusion test optimizes PCa detection compared with that of single biomarker, which would lead to a considerable reduction of the number of prostate biopsies. In this review, we focused on the potential use of PCA3 and TMPRSS2-ERG gene fusion detection in the diagnosis of PCa.

Alcohol-responsive Action Myoclonus of the Leg in Prostate Cancer: A Novel Paraneoplastic Syndrome?

Background

Paraneoplastic movement disorders in prostate cancer are rare, and to our knowledge paraneoplastic myoclonus has not previously been reported.

Case Report

We report two men with adenocarcinoma of the prostate who developed isolated alcohol-responsive action myoclonus of one leg. Myoclonus was absent at rest but triggered by movement, standing, or walking. Evaluations excluded malignant invasion of the nervous system, and testing for commercial paraneoplastic antibodies in serum and cerebrospinal fluid were unrevealing. Both patients experienced significant improvement with alcohol, and sodium oxybate was used in one patient with good initial benefit.

Discussion

Alcohol-responsive leg myoclonus might be a novel paraneoplastic syndrome associated with prostate cancer. The nature of the syndrome and the source of the myoclonus are currently unknown.

Emerging mechanisms of resistance to androgen receptor inhibitors in prostate cancer

During the past 10 years, preclinical studies implicating sustained androgen receptor (AR) signalling as the primary driver of castration-resistant prostate cancer (CRPC) have led to the development of novel agents targeting the AR pathway that are now in widespread clinical use. These drugs prolong the survival of patients with late-stage prostate cancer but are not curative. In this Review, we highlight emerging mechanisms of acquired resistance to these contemporary therapies, which fall into the three broad categories of restored AR signalling, AR bypass signalling and complete AR independence. This diverse range of resistance mechanisms presents new challenges for long-term disease control, which may be addressable through early use of combination therapies guided by recent insights from genomic landscape studies of CRPC.

Somatostatin imaging of neuroendocrine-differentiated prostate cancer

After prolonged androgen deprivation therapy, a subset of castrate-resistant prostate cancer patients will develop neuroendocrine prostate cancer (NEPC) associated with resistance to further hormonal therapy and frequent visceral metastases. Imaging the presence of somatostatin receptors on the cancer cell surface may provide a readily available, noninvasive means to distinguish adenocarcinoma from NEPC. This distinction is important for therapeutic decision making and may open the door for developing novel radionuclide targets for the treatment of this aggressive subtype of prostate cancer. We describe a case of NEPC successfully imaged using In-labeled octreotide.

Genitourinary small cell malignancies: prostate and bladder

Small cell carcinoma is an aggressive malignancy often associated with dismal prognosis due to the presence of advanced disease. Small cell malignancies, initially described in the lung (small cell carcinoma of the lung), can occur in extrapulmonary sites, such as prostate (small cell carcinoma of the prostate) and bladder (small cell carcinoma of the bladder), with similar clinicopathologic outcomes. There has been a paradigm shift in the management of small cell carcinoma of the lung from initial surgical treatment to use of chemotherapy followed by local therapies. Such treatment modalities have been applied to small cell carcinoma of the prostate and the bladder, with promise in improving patient survival. Use of platinum-based combination chemotherapy followed by surgical resection and/or radiation offers the most benefit. Further investigation at the molecular level may offer targeted therapies earlier in the course of the disease.

Androgen-deprivation therapy-induced aggressive prostate cancer with neuroendocrine differentiation

Most prostate cancers (PCas) are classified as acinar type (conventional) adenocarcinoma which are composed of tumor cells with luminal differentiation including the expression of androgen receptor (AR) and prostate-specific antigen (PSA). There are also scattered neuroendocrine (NE) cells in every case of adenocarcinoma. The NE cells are quiesecent, do not express AR or PSA, and their function remains unclear. We have demonstrated that IL8-CXCR2-P53 pathway provides a growth-inhibitory signal and keeps the NE cells in benign prostate and adenocarcinoma quiescent. Interestingly, some patients with a history of adenocarcinoma recur with small cell neuroendocrine carcinoma (SCNC) after hormonal therapy, and such tumors are composed of pure NE cells that are highly proliferative and aggressive, due to P53 mutation and inactivation of the IL8-CXCR2-P53 pathway. The incidence of SCNC will likely increase due to the widespread use of novel drugs that further inhibit AR function or intratumoral androgen synthesis. A phase II trial has demonstrated that platinum-based chemotherapy may be useful for such therapy-induced tumors.

Polycomb-mediated silencing in neuroendocrine prostate cancer

Background

Neuroendocrine prostate cancer (NEPC) is a highly aggressive subtype of prostate cancer (PCa) for which the median survival remains less than a year. Current treatments are only palliative in nature, and the lack of suitable pre-clinical models has hampered previous efforts to develop novel therapeutic strategies. Addressing this need, we have recently established the first in vivo model of complete neuroendocrine transdifferentiation using patient-derived xenografts. Few genetic differences were observed between parental PCa and relapsed NEPC, suggesting that NEPC likely results from alterations that are epigenetic in nature. Thus, we sought to identify targetable epigenetic regulators whose expression was elevated in NEPC using genome-wide profiling of patient-derived xenografts and clinical samples.

Results

Our data indicate that multiple members of the polycomb group (PcG) family of transcriptional repressors were selectively upregulated in NEPC. Notably, CBX2 and EZH2 were consistently the most highly overexpressed epigenetic regulators across multiple datasets from clinical and xenograft tumor tissues. Given the striking upregulation of PcG genes and other transcriptional repressors, we derived a 185-gene list termed ‘neuroendocrine-associated repression signature’ (NEARS) by overlapping transcripts downregulated across multiple in vivo NEPC models. In line with the striking upregulation of PcG family members, NEARS was preferentially enriched with PcG target genes, suggesting a driving role for PcG silencing in NEPC. Importantly, NEARS was significantly associated with high-grade tumors, metastatic progression, and poor outcome in multiple clinical datasets, consistent with extensive literature linking PcG genes and aggressive disease progression.

Conclusions

We have explored the epigenetic landscape of NEPC and provided evidence of increased PcG-mediated silencing associated with aberrant transcriptional regulation of key differentiation genes. Our results position CBX2 and EZH2 as potential therapeutic targets in NEPC, providing opportunities to explore novel strategies aimed at reversing epigenetic alterations driving this lethal disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0074-4) contains supplementary material, which is available to authorized users.

Mouse models of prostate cancer: picking the best model for the question

When the National Institutes of Health Mouse Models of Human Cancer Consortium initiated the Prostate Steering Committee 15 years ago, there were no genetically engineered mouse (GEM) models of prostate cancer (PCa). Today, a PubMed search for "prostate cancer mouse model" yields 3,200 publications and this list continues to grow. The first generation of GEM utilized the newly discovered and characterized probasin promoter driving viral oncogenes such as Simian virus 40 large T antigen to yield the LADY and TRAMP models. As the PCa research field has matured, the second generation of models has incorporated the single and multiple molecular changes observed in human disease, such as loss of PTEN and overexpression of Myc. Application of these models has revealed that mice are particularly resistant to developing invasive PCa, and once they achieve invasive disease, the PCa rarely resembles human disease. Nevertheless, these models and their application have provided vital information on human PCa progression. The aim of this review is to provide a brief primer on mouse and human prostate histology and pathology, provide descriptions of mouse models, as well as attempt to answer the age old question: Which GEM model of PCa is the best for my research question?

UK single centre experience of rare and atypical variant of castrate-resistant prostate cancer: Poorly differentiated neuroendocrine small-cell carcinoma

Background:

We report on the emergence of a rare and atypical variant of castrate-resistant prostate cancer (CRPC) that is characterised by transformation into poorly differentiated neuroendocrine small-cell carcinoma (NSCC). The existence of this variant was previously described in isolated case reports and small case-studies, but as yet there has been no UK series reported in the literature.

Methods:

Between January 2010 and January 2014, eight cases were presented in our local multi-disciplinary team meeting having a diagnosis of NSCC arising on a background of prostate cancer treated with androgen deprivation therapy. We performed a retrospective review of the clinical records of these patients, to identify the mode of presentation, diagnostic investigations, pathological characteristics, and subsequent treatment and survival outcomes.

Results:

The median patient age was 77 years (range, 68 – 84), with a median time interval of 25 months (range, 7 – 83) between the original diagnosis and subsequent transformation to NSCC. The median prostate-specific antigen (PSA) was 4 ng/ml, at presentation. Most patients presented with local progression, combined with high-volume and atypical sites of metastasis (e.g. brain, pancreas and penis). Patients developed a good initial response to platinum-based chemotherapy, but responses were short-lived and prognosis poor, with a median overall survival (OS) of 8 months.

Conclusion:

Prostate NSCC represents an atypical variant of CRPC with significant therapeutic and prognostic implications. Based on our observations, we have proposed a clinical algorithm for early diagnosis and appropriate management of these patients.

Androgen-targeted therapy-induced epithelial mesenchymal plasticity and neuroendocrine transdifferentiation in prostate cancer: an opportunity for intervention

Androgens regulate biological pathways to promote proliferation, differentiation, and survival of benign and malignant prostate tissue. Androgen receptor (AR) targeted therapies exploit this dependence and are used in advanced prostate cancer to control disease progression. Contemporary treatment regimens involve sequential use of inhibitors of androgen synthesis or AR function. Although targeting the androgen axis has clear therapeutic benefit, its effectiveness is temporary, as prostate tumor cells adapt to survive and grow. The removal of androgens (androgen deprivation) has been shown to activate both epithelial-to-mesenchymal transition (EMT) and neuroendocrine transdifferentiation (NEtD) programs. EMT has established roles in promoting biological phenotypes associated with tumor progression (migration/invasion, tumor cell survival, cancer stem cell-like properties, resistance to radiation and chemotherapy) in multiple human cancer types. NEtD in prostate cancer is associated with resistance to therapy, visceral metastasis, and aggressive disease. Thus, activation of these programs via inhibition of the androgen axis provides a mechanism by which tumor cells can adapt to promote disease recurrence and progression. Brachyury, Axl, MEK, and Aurora kinase A are molecular drivers of these programs, and inhibitors are currently in clinical trials to determine therapeutic applications. Understanding tumor cell plasticity will be important in further defining the rational use of androgen-targeted therapies clinically and provides an opportunity for intervention to prolong survival of men with metastatic prostate cancer.

Next generation patient-derived prostate cancer xenograft models

There is a critical need for more effective therapeutic approaches for prostate cancer. Research in this area, however, has been seriously hampered by a lack of clinically relevant, experimental in vivo models of the disease. This review particularly focuses on the development of prostate cancer xenograft models based on subrenal capsule grafting of patients’ tumor tissue into nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. This technique allows successful development of transplantable, patient-derived cancer tissue xenograft lines not only from aggressive metastatic, but also from localized prostate cancer tissues. The xenografts have been found to retain key biological properties of the original malignancies, including histopathological and molecular characteristics, tumor heterogeneity, response to androgen ablation and metastatic ability. As such, they are highly clinically relevant and provide valuable tools for studies of prostate cancer progression at cellular and molecular levels, drug screening for personalized cancer therapy and preclinical drug efficacy testing; especially when a panel of models is used to cover a broader spectrum of the disease. These xenograft models could therefore be viewed as next-generation models of prostate cancer.

The impact of PSA and digital rectal examination on the risk of prostate cancer specific mortality in men with a PSA level <2.5 ng/ml

INTRODUCTION

It is unknown whether a normal range, diagnostic serum prostate specific antigen (PSA) level's influence on prostate cancer specific mortality (PCSM) is dependent upon digital rectal examination (DRE) findings.

METHODS

Between 2004 and 2007, 9081 men diagnosed with non-palpable (T1c, N=1710) or palpable (T2-T4, N=7371) and non-metastatic prostate cancer (PC) were identified from surveillance, epidemiology, and end results data, selected based on pre-treatment PSA<2.5 ng/ml. A multivariable competing risks regression model evaluated whether DRE findings interacted with PSA level in predicting risk of PCSM.

RESULTS

After median follow-up of 2.83 years, 118 of 548 deaths (21.5%) were due to PC. Increasing diagnostic PSA was associated with increased risk of PCSM (AHR=3.52; 95% CI: 1.25-9.89; P=.017) in men with T1c, Gleason score 7-10 PC, but decreased PCSM risk (AHR=0.66; 95% CI: 0.52-0.83; P<.001) for men with T2-T4 PC and any Gleason score.

DISCUSSION

For men with diagnostic PSA level <2.5 ng/ml and palpable PC, risk of early PCSM increases by 34% for a 1 point decrease in PSA from 2. This suggests the existence of clinically detectable, low PSA secreting disease with an elevated risk of early PCSM, highlighting the importance of the DRE in men with PC and normal range, diagnostic PSA.

Hyperpolarized 13C MR for molecular imaging of prostate cancer

Hyperpolarization using dissolution dynamic nuclear polarization has emerged as a versatile method to dramatically improve the MR signal of low-sensitivity nuclei. This technique facilitates the study of real-time metabolism in vitro and in vivo using (13)C-enriched substrates and has been applied to numerous models of human disease. In particular, several mechanisms underlying prostate cancer have been interrogated using hyperpolarized (13)C MR spectroscopy. This review highlights key metabolic shifts seen in prostate cancer, their study by hyperpolarized (13)C MR spectroscopy, and the development of new platforms for metabolic study.

Androgen receptor splice variants in the era of enzalutamide and abiraterone

The FDA approvals of enzalutamide and abiraterone have rapidly changed the clinical landscape of prostate cancer treatment. Both drugs were designed to further suppress androgen receptor (AR) signaling, which is restored following first-line androgen deprivation therapies. Resistance to enzalutamide and abiraterone, however, is again marked by a return of AR signaling, indicating a remarkable "addiction" of prostate cancer cells to the AR pathway. Several mechanisms of castration resistance have been uncovered in the past decades, featuring a wide spectrum of molecular alterations that may explain sustained AR signaling in castration-resistant prostate cancers (CRPC). Among these, the androgen receptor splice variants (AR-Vs), particularly variant 7 (AR-V7), have been implicated in resistance to enzalutamide and abiraterone in preclinical studies, and they cannot be targeted by currently available AR-directed drugs. Drug development for AR-V-associated CRPC may therefore be necessary to augment the preexisting treatment repertoire. In this mini-review, we will discuss general mechanisms of resistance to AR-directed therapies, with a focus on the role of androgen receptor splice variants in the new era of treating advanced prostate cancer with enzalutamide and abiraterone.

High frequency of TERT promoter mutation in small cell carcinoma of bladder, but not in small cell carcinoma of other origins

TERT promoter mutations were recently discovered in melanoma by next generation sequencing. Subsequently, several malignancies including urothelial carcinoma were also found to be associated with the same TERT promoter mutations. Small cell carcinoma (SCC) of the urinary bladder is a rare subtype with an aggressive clinical course. Despite the frequent occurrence of TERT promoter mutations in urothelial carcinoma, the incidence of the mutations in SCC of the urinary bladder is unknown. In addition, as a potential molecular marker to distinguish SCC of the urinary bladder from SCC of the prostate, lung (SCLC) and other origins, this information may be clinically useful. We collected a total of 11 cases of SCC of the urinary bladder (10 cases are primary SCC of the urinary bladder; 1 case has primary SCC of the urinary bladder and liver metastasis). We also included 20 cases of SCLC, 2 cases of SCC of the prostate, 5 cases of Merkel cell carcinoma, and 6 cases of SCC from other sites (cervical, GE junction, breast, and soft tissue). In addition, 3 cases of non-neoplastic tissue from the matched SCC of bladder patient and 14 cases of benign urinary bladder were also included. All tumor sections have been examined to confirm the diagnosis and to make sure more than 20% are of tumor content. Genomic DNA was isolated from FFPE tissue and a fragment of the TERT promoter (145 bp) was amplified by PCR. The TERT promoter mutations are determined by bi-directional Sanger sequencing. All (11/11) SCC of the urinary bladder bear TERT promoter mutation C228T. Neither of SCC from all other origins nor matched non-neoplastic tissue contains the TERT promoter mutations. We demonstrated a high frequency TERT promoter mutation in SCC of the urinary bladder, but not in SCC of other origin, such as the prostate. The findings further illustrate molecular differences between SCC of the urinary bladder and SCC of other origins, despite their shared morphologic and immunophenotypic similarities. The TERT promoter mutation may be a biomarker differentiating SCC of the urinary bladder from SCC of other origins.

Population-based analysis of treatment modalities and survival for clinically localized small-cell carcinoma of the prostate

BACKGROUND

Small-cell carcinoma of the prostate is an aggressive cancer whose rarity has prevented the development of a consensus management approach. The objective of the current study was to determine the treatment patterns and evaluate factors affecting overall survival for patients with localized small-cell carcinoma of the prostate.

METHODS

After querying the National Cancer Database, we identified all patients diagnosed with localized small-cell carcinoma of the prostate between 1998 and 2011 (n=287). Using Kaplan-Meier curves and Cox regression analyses, we assessed the effect of treatment and clinical stage on overall survival.

RESULTS

Treatments included radiation therapy in 46% (n=131), chemotherapy in 38% (n=107), androgen deprivation therapy (ADT) in 22% (n=63) and radical prostatectomy in 13% (n=38). Median overall survival was 14.8 months. Upon multivariate analysis, local therapy (radical prostatectomy or radiation therapy) was associated with improved survival (hazard ratio (HR) 0.23, 95% confidence interval (CI) 0.14-0.38, P<0.001). Advanced clinical stage predicted worse survival among all men (cT3: HR 2.83, 95% CI 1.27-6.32, P=0.011; cT4: HR 3.26, 95% CI 1.50-7.07, P=0.003) and men who received local therapy (cT3: HR 4.67, 95% CI 1.41-15.44, P=0.012; cT4: HR 4.01, 95% CI 1.14-14.08, P=0.03) but not among men who received no local therapy (cT3: HR 1.64, 95% CI 0.51-5.27, P=0.4; cT4: HR 2.35, 95% CI 0.74-7.48, P=0.15). Age, receipt of chemotherapy and ADT, and clinical stage T2 disease (compared with T1) did not predict survival.

CONCLUSION

Men with localized small-cell carcinoma of the prostate have a poor overall survival. Local therapy may represent a suitable and underused modality for select patients.

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.

Small cell carcinoma of the prostate

Pure small-cell carcinoma (SCC) of the prostate is a rare entity and one of the most aggressive malignancies of the prostate. Histologically, prostatic SCCs of the prostate are part of a spectrum of anaplastic tumours of the prostate and are similar to SCCs of the lungs. In most cases, SCC of the prostate is associated with conventional prostatic adenocarcinoma. Both components of these mixed tumours frequently share molecular alterations such as ERG gene rearrangements or AURKA and MYCN amplifications, suggesting a common clonal origin. The clinical behaviour of small-cell prostate carcinomas is characterized by extensive local disease, visceral disease, and low PSA levels despite large metastatic burden. Commonly, the emergence of the SCC occurs in patients with high-grade adenocarcinoma who are often treated with androgen deprivation treatment (ADT). However, SCCs do not usually benefit from ADT. A biopsy of accessible lesions is strongly recommended to identify those with SCC pathological features, as management is undoubtedly affected by this finding. Chemotherapy is the standard approach for treating patients with either localized or advanced prostatic SCC. Despite the emergence of more-aggressive treatment modalities, the prognosis of men with prostatic SCC remains dismal.

High fidelity patient-derived xenografts for accelerating prostate cancer discovery and drug development

Standardized and reproducible preclinical models that recapitulate the dynamics of prostate cancer are urgently needed. We established a bank of transplantable patient-derived prostate cancer xenografts that capture the biologic and molecular heterogeneity currently confounding prognostication and therapy development. Xenografts preserved the histopathology, genome architecture, and global gene expression of donor tumors. Moreover, their aggressiveness matched patient observations, and their response to androgen withdrawal correlated with tumor subtype. The panel includes the first xenografts generated from needle biopsy tissue obtained at diagnosis. This advance was exploited to generate independent xenografts from different sites of a primary site, enabling functional dissection of tumor heterogeneity. Prolonged exposure of adenocarcinoma xenografts to androgen withdrawal led to castration-resistant prostate cancer, including the first-in-field model of complete transdifferentiation into lethal neuroendocrine prostate cancer. Further analysis of this model supports the hypothesis that neuroendocrine prostate cancer can evolve directly from adenocarcinoma via an adaptive response and yielded a set of genes potentially involved in neuroendocrine transdifferentiation. We predict that these next-generation models will be transformative for advancing mechanistic understanding of disease progression, response to therapy, and personalized oncology.

Rb loss is characteristic of prostatic small cell neuroendocrine carcinoma

PURPOSE

Small cell neuroendocrine carcinoma of the prostate is likely to become increasingly common with recent advances in pharmacologic androgen suppression. Thus, developing molecular markers of small cell differentiation in prostate cancer will be important to guide the diagnosis and therapy of this aggressive tumor.

EXPERIMENTAL DESIGN

We examined the status of RB1, TP53, and PTEN in prostatic small cell and acinar carcinomas via immunohistochemistry (IHC), copy-number alteration analysis, and sequencing of formalin-fixed paraffin-embedded specimens.

RESULTS

We found retinoblastoma (Rb) protein loss in 90% of small cell carcinoma cases (26 of 29) with RB1 allelic loss in 85% of cases (11 of 13). Of acinar tumors occurring concurrently with prostatic small cell carcinoma, 43% (3 of 7) showed Rb protein loss. In contrast, only 7% of primary high-grade acinar carcinomas (10 of 150), 11% of primary acinar carcinomas with neuroendocrine differentiation (4 of 35), and 15% of metastatic castrate-resistant acinar carcinomas (2 of 13) showed Rb protein loss. Loss of PTEN protein was seen in 63% of small cell carcinomas (17 of 27), with 38% (5 of 13) showing allelic loss. By IHC, accumulation of p53 was observed in 56% of small cell carcinomas (14 of 25), with 60% of cases (6 of 10) showing TP53 mutation.

CONCLUSIONS

Loss of RB1 by deletion is a common event in prostatic small cell carcinoma and can be detected by a validated IHC assay. As Rb protein loss rarely occurs in high-grade acinar tumors, these data suggest that Rb loss is a critical event in the development of small cell carcinomas and may be a useful diagnostic and potential therapeutic target.

Lessons from in-vivo models of castration-resistant prostate cancer

PURPOSE OF REVIEW

Although the treatment of castration-resistant prostate cancer (CRPC) has benefited from the use of increasingly potent androgen synthesis inhibitors and androgen receptor (AR) antagonists, it is only marginally effective. There is therefore a critical need for a better understanding of the mechanisms underlying the CRPC development and more effective therapeutic approaches. Here, we focus on the advancements reported in the last 18 months, particularly with regard to the mechanisms of castration resistance and potential therapeutic targets emerging from the studies with in-vivo models.

RECENT FINDINGS

Recent findings indicate that AR-dependent mechanisms, for example, increased expression of CYP17A1 and AR splice variants, play important roles in in-vivo castration resistance to new antiandrogens and androgen synthesis inhibitors. Whereas current therapeutic approaches focus on AR-dependent CRPC, studies based on genetically engineered mouse models indicate that castration resistance can develop in the absence of robust AR signaling. Furthermore, increasing evidence suggests that cellular plasticity of prostate adenocarcinoma allows AR-independent CRPC development via various adaptive mechanisms.

SUMMARY

Significant progress has been made in the understanding of AR-dependent and AR-independent mechanisms involved in the development of CRPC. This may lead to identification of new therapeutic targets and improved therapy.

Prostatic stromal neoplasms: differential diagnosis of cystic and solid prostatic and periprostatic masses

OBJECTIVE

The objectives of this article are to illustrate the radiologic-pathologic correlation of prostate stromal neoplasms and to review the imaging appearances of cystic and solid prostatic and periprostatic masses that may mimic prostatic stromal neoplasms.

CONCLUSION

The differential diagnosis for cystic and solid masses in the prostate is broad, and masses arising from periprostatic structures may mimic the appearance of primary prostatic diseases. Attention to clinical and imaging features is helpful in narrowing the differential diagnosis.

Prostate cancer genomics by high-throughput technologies: genome-wide association study and sequencing analysis

Prostate cancer (PC) is the most common malignancy in males. It is evident that genetic factors at both germline and somatic levels play critical roles in prostate carcinogenesis. Recently, genome-wide association studies (GWAS) by high-throughput genotyping technology have identified more than 70 germline variants of various genes or chromosome loci that are significantly associated with PC susceptibility. They include multiple 8q24 loci, prostate-specific genes, and metabolism-related genes. Somatic alterations in PC genomes have been explored by high-throughput sequencing technologies such as whole-genome sequencing and RNA sequencing, which have identified a variety of androgen-responsive events and fusion transcripts represented by E26 transformation-specific (ETS) gene fusions. Recent innovations in high-throughput genomic technologies have enabled us to analyze PC genomics more comprehensively, more precisely, and on a larger scale in multiple ethnic groups to increase our understanding of PC genomics and biology in germline and somatic studies, which can ultimately lead to personalized medicine for PC diagnosis, prevention, and therapy. However, these data indicate that the PC genome is more complex and heterogeneous than we expected from GWAS and sequencing analyses.

Impact of age on clinical presentation, treatment, and cancer-specific survival of patients with small-cell carcinoma of the prostate

Background

The effects of age on clinical presentation, treatment, and outcomes for patients with small-cell carcinoma of the prostate (SCCP) are unclear.

Methods

A retrospective review was performed on 259 patients who were identified with SCCP in the national Surveillance, Epidemiology, and End Results (SEER) registry from January 1973 to December 2004. The patients were categorized into two groups according to age at diagnosis, ie, younger than 75 years (n = 158, 61%) or 75 years and older (n = 101, 39%). Patient and treatment characteristics and cancer-specific survival were compared between the groups. Multivariate analysis was performed to identify independent prognostic factors associated with cancer-specific survival.

Results

The median age of the patients was 72 (30–95) years. There was no significant difference in terms of tumor characteristics, concomitant adenocarcinoma grade, SEER stage, and treatment (including prostatectomy and radiation therapy) received between the groups. Median cancer-specific survival was 19 months (95% confidence interval 13–25). By multivariate Cox proportional hazard modeling, older age group (hazard ratio [HR] 1.95; P = 0.001), concomitant high-grade adenocarcinoma (HR 7.13; P = 0.007), and not having prostatectomy (HR 3.77; P = 0.005) were found to be significant independent predictors of poor cancer-specific survival.

Conclusion

Older patients with SCCP had increased risk of poor cancer-specific survival. Whether this age-related poor outcome can be attributed to more aggressive tumor biology in older patients, or is simply a refection of age-related poor performance status and suboptimal chemotherapy needs further investigation.

False-negative bone scan and choline pet/ct study in a case of prostate cancer: the pitfall of the small cell prostate carcinoma variant

We present a rare variant of prostate carcinoma. The patient is a 45-year-old male with elevated prostate-specific antigen levels at screening. Magnetic resonance imaging revealed hyperenhancing lesions throughout the axial skeleton. The fluorine-18 fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) scan showed no abnormal bone findings. Subsequently, a technetium-99 methydiphosphonate (Tc99m-MDP) bone scan was performed, with additional correlative single-photon emission computed tomography (SPECT)/CT imaging of the pelvis and the results were essentially normal. A percutaneous core biopsy of one of the bone lesions in L5 was performed and histology confirmed small cell (neuroendocrine) variant of prostate cancer. Our case illustrates a possible pitfall in molecular imaging of prostate carcinomas, whereby both bone scintigraphy and FCH PET/CT scans showed no definite bone lesions to correlate with marrow signal abnormalities seen on MR imaging. This highlights the need for caution in the diagnostic evaluation of prostate cancers with known small cell variants.

A useful treatment for patients with advanced mixed-type small cell neuroendocrine carcinoma of the prostate: A case report

Treating extended prostatic small cell neuroendocrine carcinoma (PSCNC) is extremely difficult and no standard treatment has yet been established. We experienced a case of advanced mixed-type PSCNC in which the patient achieved long-term survival and local control following combined therapy. Locally advanced PSCNC causing lower urinary obstruction was detected during androgen-ablation therapy for stage D2 mixed adenocarcinoma PSCNC. The patient was treated with intra-arterial infusion chemotherapy using a reservoir system and external-beam radiotherapy (EBRT) to the whole pelvis and local tumor. After chemoradiotherapy, the patient’s lower urinary obstruction was reduced and did not return during the remaining 40 months of the patient’s life. The patient survived for 70 months following the start of the androgen-ablation therapy. The present study reports a useful treatment for advanced mixed-type PSCNC, androgen-ablation therapy and chemoradiotherapy. The present results also suggest that the prognostic factors for advanced mixed-type PSCNC are the sensitivity of the conventional adenocarcinoma to androgen-ablation therapy, degree of metastasis and extent of the small cell neuroendocrine carcinoma component.

Molecular characterization of neuroendocrine prostate cancer and identification of new drug targets

Neuroendocrine prostate cancer (NEPC) is an aggressive subtype of prostate cancer that most commonly evolves from preexisting prostate adenocarcinoma (PCA). Using Next Generation RNA-sequencing and oligonucleotide arrays, we profiled 7 NEPC, 30 PCA, and 5 benign prostate tissue (BEN), and validated findings on tumors from a large cohort of patients (37 NEPC, 169 PCA, 22 BEN) using IHC and FISH. We discovered significant overexpression and gene amplification of AURKA and MYCN in 40% of NEPC and 5% of PCA, respectively, and evidence that that they cooperate to induce a neuroendocrine phenotype in prostate cells. There was dramatic and enhanced sensitivity of NEPC (and MYCN overexpressing PCA) to Aurora kinase inhibitor therapy both in vitro and in vivo, with complete suppression of neuroendocrine marker expression following treatment. We propose that alterations in Aurora kinase A and N-myc are involved in the development of NEPC, and future clinical trials will help determine from the efficacy of Aurora kinase inhibitor therapy.

SIGNIFICANCE

We report on the largest in-depth molecular analysis of NEPC and provide new insight into molecular events involved in the progression of prostate cancer.

Small cell cancer of the prostate

De novo small cell cancer of the prostate is a rare tumor and has different presentation, behavior, and outcome compared with adenocarcinoma. A 66-year-old man presented with symptoms masquerading as a rectal tumor. Primary symptoms were intermittent constipation and diarrhea without any urinary symptoms. Initial staging showed only 2 large pelvic nodes. Prostate-specific antigen was 4.8 ng/L. A transrectal prostate biopsy confirmed small cell histology. After having no response to hormones and carboplatin-etoposide, a course of palliative radiotherapy, docetaxel chemotherapy, and defunctioning colostomy offered palliation. Liver and lytic bone metastases developed later; the patient died 9 months after the presentation.

Plumbagin inhibits prostate cancer development in TRAMP mice via targeting PKCε, Stat3 and neuroendocrine markers

Plumbagin (PL), 5-hydroxy-2-methyl-1,4-naphthoquinone, is a quinoid constituent isolated from the roots of the medicinal plant Plumbago zeylanica L. (also known as chitrak). PL has also been found in Juglans regia (English Walnut), Juglans cinerea (whitenut) and Juglans nigra (blacknut). The roots of P. zeylanica have been used in Indian and Chinese systems of medicine for more than 2500 years for the treatment of various types of ailments. We were the first to report that PL inhibits the growth and invasion of hormone refractory prostate cancer (PCa) cells [Aziz,M.H. et al. (2008) Plumbagin, a medicinal plant-derived naphthoquinone, is a novel inhibitor of the growth and invasion of hormone-refractory prostate cancer. Cancer Res., 68, 9024-9032.]. Now, we present that PL inhibits in vivo PCa development in the transgenic adenocarcinoma of mouse prostate (TRAMP). PL treatment (2 mg/kg body weight i.p. in 0.2 ml phosphate-buffered saline, 5 days a week) to FVB-TRAMP resulted in a significant (P < 0.01) decrease in prostate tumor size and urogenital apparatus weights at 13 and 20 weeks. Histopathological analysis revealed that PL treatment inhibited progression of prostatic intraepithelial neoplasia (PIN) to poorly differentiated carcinoma (PDC). No animal exhibited diffuse tumor formation in PL-treated group at 13 weeks, whereas 75% of the vehicle-treated mice elicited diffuse PIN and large PDC at this stage. At 20 weeks, 25% of the PL-treated animals demonstrated diffuse PIN and 75% developed small PDC, whereas 100% of the vehicle-treated mice showed large PDC. PL treatment inhibited expression of protein kinase C epsilon (PKCε), signal transducers and activators of transcription 3 phosphorylation, proliferating cell nuclear antigen and neuroendocrine markers (synaptophysin and chromogranin-A) in excised prostate tumor tissues. Taken together, these results further suggest PL could be a novel chemopreventive agent against PCa.

Complete chemotherapeutic regression of a non-metastatic case of primary pure small cell carcinoma of the prostate

Pure small cell carcinoma of the prostate (SCPCa) is a very rare condition usually with poor survival after diagnosis. It seems to show different clinical features compared to other prostate cancer subtypes, specifically adenocarcinoma. Here, we present a 74-year-old man early diagnosed with SCPCa treated with a cisplatine and etoposide regimen. There was no metastasis found in imaging studies and bone scan. The patient mostly complained of obstructive symptoms which were relieved after resection. Interestingly, our patient experienced a disease free condition after chemotherapy and no further progression was found. This could implicate the critical role of early diagnosis in the treatment of SCPCa despite its aggressive nature.

ERG-TMPRSS2 rearrangement is shared by concurrent prostatic adenocarcinoma and prostatic small cell carcinoma and absent in small cell carcinoma of the urinary bladder: evidence supporting monoclonal origin

Prostatic carcinoma is a heterogeneous disease with frequent multifocality and variability in morphology. Particularly, prostatic small cell carcinoma is a rare variant with aggressive behavior. Distinction between small cell carcinoma of the prostate and urinary bladder may be challenging, especially in small biopsy specimens without associated prostatic adenocarcinoma or urothelial carcinoma. Recently, gene fusions between ETS genes, particularly ETS-related gene (ERG), and transmembrane protease, serine 2 (TMPRSS2) have been identified as a frequent event in prostate cancer. Thus, molecular methods may be helpful in determining the primary site of small cell carcinoma. Thirty cases of prostatic small cell carcinoma from the authors' archives were studied, among which 13 had concurrent prostatic adenocarcinoma. Tricolor fluorescence in situ hybridization (FISH) was performed on formalin-fixed paraffin-embedded tissue sections with a probe cocktail for 3'/5' ERG and TMPRSS2. Cases of small cell carcinoma of the bladder and conventional prostatic adenocarcinoma (25 each) were also tested as controls. ERG gene alterations were found only in prostate malignancies and not in benign prostatic tissue or bladder small cell carcinoma. TMPRSS2-ERG gene fusion was found in 47% (14/30) of prostatic small cell carcinoma. Of cases with concurrent prostatic adenocarcinoma, 85% (11/13) had identical findings in both components. In 20% of rearranged cases, the ERG abnormality was associated with 5' ERG deletion. In 17% (5/30) of cases, gain of the 21q22 locus was present. Two cases showed discordant aberrations in the small cell carcinoma and adenocarcinoma, one with deletion of 5' ERG and one with gain of chromosome 21q, both in only the adenocarcinoma component. Small cell carcinoma of the prostate demonstrates TMPRSS2-ERG rearrangement with comparable frequency to prostatic adenocarcinoma. In cases with concurrent adenocarcinoma and small cell carcinoma, the majority showed identical abnormalities in both components, indicating a likely common clonal origin. Discordant alterations were present in rare cases, suggesting that acquisition of additional genetic changes in multifocal tumors may be responsible for disease progression to a more aggressive phenotype. TMPRSS2-ERG fusion is absent in bladder small cell carcinoma, supporting the utility of FISH in distinguishing prostate from bladder primary tumors and identifying metastatic small cell carcinoma of unknown origin.