Neuroendocrine differentiated small cell carcinoma presenting as recurrent prostate cancer after androgen deprivation therapy

Molecular Imaging in Recurrent Prostate Cancer Presented as a Mixed Small Neuroendocrine Tumor/Acinar Adenocarcinoma

Molecular imaging is an important tool for evaluating patients with prostate cancer, including those with hybrid histopathology. Although rare, mixed small neuroendocrine tumor/acinar adenocarcinoma exhibit aggressive behavior that necessitates optimal therapy. Molecular imaging has been implemented previously to assess radioligand therapy eligibility in such cases. Interestingly, the uptake of radiotracers targeting prostate-specific membrane antigen (PSMA) and somatostatin receptor may be reduced and can potentially lead to false negative readings in certain tumor types with hybrid features. Therefore, physicians should be aware of different kinds of disparities when assessing these tumor types with the aforementioned modalities.

Histologic transformation in lung cancer: when one door shuts, another opens

Histologic transformation (HT) is a major cause of drug resistance to therapy in patients with lung cancer. HTs to small-cell lung cancer (SCLC) have been reported frequently in patients with epidermal growth factor receptor (EGFR)-mutated lung cancer. Although HTs have an impact on the clinical outcomes in patients owing to a high refractoriness to treatments, there is limited data on the prevalence, causes, mechanisms, treatment efficacy, and future treatment strategies. In this review, we assess the literature regarding HTs comprehensively, including those describing EGFR-tyrosine kinase inhibitors, other molecular targeted drugs, and immune checkpoint inhibitors. Furthermore, we discuss the mechanisms of HTs and the lineage plasticity to SCLC and squamous cell carcinoma in lung cancer. In addition, we summarize the treatment efficacy and future perspectives of HTs in patients with lung cancer, and propose better management strategies for this group of patients.

Rare Case of Small Cell Metastatic Prostatic Adenocarcinoma, Properly Staged by 68Ga-PSMA PET/CT Scan

ABSTRACT

Small cell carcinoma (SCC) of the prostate is a very rare entity and one of most aggressive neuroendocrine malignancies of prostate. We present a 60-year-old man with pathology-proven prostatic SCC by transrectal biopsy with ultrasonography guidance and Gleason score of 5 + 5. He was referred to perform 68Ga-PSMA PET/CT scan for staging. The scan showed PSMA uptake in the prostate bed and multiple large pelvic lymph nodes. As we know, 68Ga-PSMA uptake in the de novo form of SCC of prostate is not commonly found in the literature.

Multi-omic analysis of lung tumors defines pathways activated in neuroendocrine transformation

Lineage plasticity is implicated in treatment resistance in multiple cancers. In lung adenocarcinomas (LUADs) amenable to targeted therapy, transformation to small cell lung cancer (SCLC) is a recognized resistance mechanism. Defining molecular mechanisms of neuroendocrine (NE) transformation in lung cancer has been limited by a paucity of pre-/post-transformation clinical samples. Detailed genomic, epigenomic, transcriptomic, and protein characterization of combined LUAD/SCLC tumors, as well as pre-/post-transformation samples, support that NE transformation is primarily driven by transcriptional reprogramming rather than mutational events. We identify genomic contexts in which NE transformation is favored, including frequent loss of the 3p chromosome arm. We observed enhanced expression of genes involved in PRC2 complex and PI3K/AKT and NOTCH pathways. Pharmacological inhibition of the PI3K/AKT pathway delayed tumor growth and NE transformation in an EGFR-mutant patient-derived xenograft model. Our findings define a novel landscape of potential drivers and therapeutic vulnerabilities of neuroendocrine transformation in lung cancer.

Immunotherapy for Metastatic Prostate Cancer: Current and Emerging Treatment Options

The advent of immunotherapy has revolutionized cancer treatment. Prostate cancer has an immunosuppressive microenvironment and a low tumor mutation burden, resulting in low neoantigen expression. The consensus was that immunotherapy would be less effective in prostate cancer. However, recent studies have reported that prostate cancer does have a high number of DNA damage and repair gene defects. Immunotherapies that have been tested in prostate cancer so far have been mainly vaccines and checkpoint inhibitors. A combination of genomically targeted therapies, with approaches to alleviate immune response and thereby make the tumor microenvironment immunologically hot, is promising.

Lineage plasticity-mediated therapy resistance in prostate cancer

Therapy resistance is a significant challenge for prostate cancer treatment in clinic. Although targeted therapies such as androgen deprivation and androgen receptor (AR) inhibition are effective initially, tumor cells eventually evade these strategies through multiple mechanisms. Lineage reprogramming in response to hormone therapy represents a key mechanism that is increasingly observed. The studies in this area have revealed specific combinations of alterations present in adenocarcinomas that provide cells with the ability to transdifferentiate and perpetuate AR-independent tumor growth after androgen-based therapies. Interestingly, several master regulators have been identified that drive plasticity, some of which also play key roles during development and differentiation of the cell lineages in the normal prostate. Thus, further study of each AR-independent tumor type and understanding underlying mechanisms are warranted to develop combinational therapies that combat lineage plasticity in prostate cancer.

Neuroendocrine differentiation in castration resistant prostate cancer. Nuclear medicine radiopharmaceuticals and imaging techniques: A narrative review

BACKGROUND

Androgen Deprivation Therapy (ADT) is the primary treatment for patients suffering from relapsing or advanced prostate cancer (PC). Hormone therapy generally guarantees adequate clinical control of the disease for some years, even in those patients affected by widespread skeletal and soft tissue metastases. Despite ADT, however, most patients treated with hormones eventually progress to castration-resistant prostate cancer (CRPC), for which there are no effective treatments. This clinical reality is an open challenge to the oncologist because of those neoplasms which elaborate neuroendocrine differentiation (NED).

METHODS

An online search of current and past literature on NED in CRPC was performed. Relevant articles dealing with the biological and pathological basis of NED, with nuclear medicine imaging in CRPC and somatostatin treatment in NED were analyzed.

EVIDENCE FROM THE LITERATURE

NED may arise in prostate cancer patients in the late stages of ADT. The onset of NED offers prognostic insight because it reflects a dramatic increase in the aggressive nature of the neoplasm. Several genetic, molecular, cytological and immunohistochemical markers are associated with this transformation. Among these, overexpression of somatostatin receptors, seen through Nuclear Medicine testing, is one of the most studied.

CONCLUSIONS

Preliminary studies show that the overexpression of somatostatin receptors related to NED in CRPC may easily be studied in vivo with PET/CT. This finding offers a potentially useful objective for targeted therapy in CRPC. If the overexpression of SSTRs is shown to afflict a significant segment of patients with CRPC, this will open further study of possible therapeutic options based on this marker.

Clinically actionable mutation profiles in patients with cancer identified by whole-genome sequencing

Next-generation sequencing (NGS) efforts have established catalogs of mutations relevant to cancer development. However, the clinical utility of this information remains largely unexplored. Here, we present the results of the first eight patients recruited into a clinical whole-genome sequencing (WGS) program in the United Kingdom. We performed PCR-free WGS of fresh frozen tumors and germline DNA at 75× and 30×, respectively, using the HiSeq2500 HTv4. Subtracted tumor VCFs and paired germlines were subjected to comprehensive analysis of coding and noncoding regions, integration of germline with somatically acquired variants, and global mutation signatures and pathway analyses. Results were classified into tiers and presented to a multidisciplinary tumor board. WGS results helped to clarify an uncertain histopathological diagnosis in one case, led to informed or supported prognosis in two cases, leading to de-escalation of therapy in one, and indicated potential treatments in all eight. Overall 26 different tier 1 potentially clinically actionable findings were identified using WGS compared with six SNVs/indels using routine targeted NGS. These initial results demonstrate the potential of WGS to inform future diagnosis, prognosis, and treatment choice in cancer and justify the systematic evaluation of the clinical utility of WGS in larger cohorts of patients with cancer.

Neuroendocrine Differentiation in Prostatic Malignancy

Neuroendocrine differentiation in prostatic malignancy is receiving considerable attention; this occurs commonly as a “focal” histological variant and, most rarely, in the form of small cell carcinoma (“oat cell carcinoma”) and carcinoid tumor. In prostate cancer, neuroendocrine differentiation may be the response to androgen deprivation and neuroendocrine products, either biogenic amines or peptides, have been shown to stimulate proliferation of androgen-ablation refractory cancer cells. Serum chromogranins, neuron-specific enolase and other neuroendocrine products as well as 111-In-chromogranin A “three step” immunoscintigraphy and somatostatin-receptor scintigraphy may be useful for predicting tumor behaviour and patient prognosis.

Several of the neuroendocrine products, particularly somatostatin analogues, are candidates for new therapeutic approaches. The paper aims to outline the advances in this field on the basis of the review of the literature.

[SMALL CELL PROSTATE CANCER PRODUCING SYNDROME OF INAPPROPRIATE SECRETION OF ANTIDIURETIC HORMONE; A CASE REPORT]

A 73-year-old man with progressive prostate cancer visited our hospital after prostate biopsy performed at another hospital. His serum PSA level was 29.02 ng/ml. CT revealed invasion of the bladder, bilateral ureters, and rectum. Otherwise, there was no evidence of metastasis. Pathological findings showed a poorly differentiated adenocarcinoma (Gleason score 4+5) and small cell carcinoma component. Two months after administering combined androgen blockade therapy, he was admitted due to severe hyponatremia caused by the inappropriate secretion of antidiuretic hormone. Furthermore, CT revealed right ureter metastasis, although the PSA levels remained low. Therefore, the patient was put on fluid restriction and sodium administration. After the patient recovered from hyponatremia, chemotherapy, including VP-16 and CDDP, was initiated. However, CT after two chemotherapy cycles revealed disease progression, with multiple bone metastases. Second-line chemotherapy, including CPT-11 and CDDP, was less effective, and the patient died 9 months after the diagnosis.

Sequential occurrence of small cell and non-small lung cancer in a male patient: Is it a transformation?

Lung cancer is one of the leading causes of cancer-related mortality and is categorized into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). We present a patient with epidermal growth factor receptor (EGFR)-mutant-NSCLC who developed metastatic SCLC after initial therapy with second-generation EGFR-tyrosine kinase inhibitor, afatinib. A 65-year-old male non-smoker was diagnosed with adenocarcinoma of the right lung, stage IVA (M1a). Due to tumor positivity for EGFR-Exon 19 deletion, the patient was started on oral afatinib, which resulted in a partial response. After ten months of treatment, he presented in the office with abdominal pain, distension, weight loss and jaundice. He had diffuse skeletal and hepatic metastases on PET/CT scan with interval progression of his cancer. Although the recurrence of lung adenocarcinoma was suspected, the patient was diagnosed with SCLC on liver biopsy. He received two cycles of chemotherapy and died due to pneumonia and sepsis.

FOXA2 is a sensitive and specific marker for small cell neuroendocrine carcinoma of the prostate

The median survival of patients with small cell neuroendocrine carcinoma is significantly shorter than that of patients with classic acinar-type adenocarcinoma. Small cell neuroendocrine carcinoma is traditionally diagnosed based on histologic features because expression of current immunohistochemical markers is inconsistent. This is a challenging diagnosis even for expert pathologists and particularly so for pathologists who do not specialize in prostate cancer. New biomarkers to aid in the diagnosis of small cell neuroendocrine carcinoma are therefore urgently needed. We discovered that FOXA2, a pioneer transcription factor, is frequently and specifically expressed in small cell neuroendocrine carcinoma compared with prostate adenocarcinoma from published mRNA-sequencing data of a wide range of human prostate cancers. We verified the expression of FOXA2 in human prostate cancer cell lines and xenografts, patient biopsy specimens, tissue microarrays of prostate cancers with lymph node metastasis, primary small cell neuroendocrine carcinoma, and metastatic treatment-related small cell neuroendocrine carcinoma and cases from a rapid autopsy program. FOXA2 expression was present in NCI-H660 and PC3 neuroendocrine cell lines, but not in LNCAP and CWR22 adenocarcinoma cell lines. Of the human prostate cancer specimens, 20 of 235 specimens (8.5%) showed diagnostic histologic features of small cell neuroendocrine carcinoma as judged histologically. Fifteen of 20 small cell neuroendocrine carcinoma tissues (75%) showed strong expression of FOXA2 (staining intensity 2 or 3). FOXA2 expression was also detected in 9 of 215 prostate cancer tissues (4.2%) that were histologically defined as adenocarcinoma. Our findings demonstrate that FOXA2 is a sensitive and specific molecular marker that may be extremely valuable in the pathologic diagnosis of small cell neuroendocrine carcinoma.

A dual yet opposite growth-regulating function of miR-204 and its target XRN1 in prostate adenocarcinoma cells and neuroendocrine-like prostate cancer cells

Androgen deprivation therapy in prostate cancer (PCa) causes neuroendocrine differentiation (NED) of prostatic adenocarcinomas (PAC) cells, leading to recurrence of PCa. Androgen-responsive genes involved in PCa progression including NED remain largely unknown. Here we demonstrated the importance of androgen receptor (AR)-microRNA-204 (miR-204)-XRN1 axis in PCa cell lines and the rat ventral prostate. Androgens downregulate miR-204, resulting in induction of XRN1 (5′-3′ exoribonuclease 1), which we identified as a miR-204 target. miR-204 acts as a tumor suppressor in two PAC cell lines (LNCaP and 22Rv1) and as an oncomiR in two neuroendocrine-like prostate cancer (NEPC) cell lines (PC-3 and CL1). Importantly, overexpression of miR-204 and knockdown of XRN1 inhibited AR expression in PCa cells. Repression of miR-34a, a known AR-targeting miRNA, contributes AR expression by XRN1. Thus we revealed the AR-miR-204-XRN1-miR-34a positive feedback loop and a dual function of miR-204/XRN1 axis in prostate cancer.

Neuroendocrine tumours in rare sites: differences in nomenclature and diagnostics-a rare and ubiquitous histotype

The diagnosis of neuroendocrine tumours in typical sites, as gastrointestinal tract and lung, is based upon well-coded criteria that have become familiar to most of the pathologists. Much more difficult is the recognition and allocation of proper nomenclature to be referred to the same histotype in locations where these tumours have a lower incidence. The aim of our review was to provide a quick handbook of the main diagnostic pitfalls known in literature that can interpose in the histopathological examination of neuroendocrine tumours in rare sites (urinary system and male genital organs, female genital organs, head and neck and breast).

Prostate cancer and neuroendocrine differentiation: more neuronal, less endocrine?

Neuroendocrine differentiation (NED) marks a structural and functional feature of certain cancers, including prostate cancer (PCa), whereby the malignant tissue contains a significant proportion of cells displaying neuronal, endocrine, or mixed features. NED cells produce, and can secrete, a cocktail of mediators commonly encountered in the nervous system, which may stimulate and coordinate cancer growth. In PCa, NED appears during advanced stages, subsequent to treatment, and accompanies treatment resistance and poor prognosis. However, the term “neuroendocrine” in this context is intrinsically vague. This article seeks to provide a framework on which a unified view of NED might emerge. First, we review the mutually beneficial interplay between PCa and neural structures, mainly supported by cell biology experiments and neurological conditions. Next, we address the correlations between PCa and neural functions, as described in the literature. Based upon the integration of clinical and basic observations, we suggest that it is legitimate to seek for true neural differentiation, or neuromimicry, in cancer progression, most notably in PCa cells exhibiting what is commonly described as NED.

Neuroendocrine Prostate Cancer (NEPC) progressing from conventional prostatic adenocarcinoma: factors associated with time to development of NEPC and survival from NEPC diagnosis-a systematic review and pooled analysis

PURPOSE

An often under-recognized late manifestation of prostate adenocarcinoma (PCa) is the development of treatment-related neuroendocrine prostate cancer (NEPC). The aim of this study is to identify the risk factors related to survival after NEPC diagnosis (NEPCS) and time from initial diagnosis of PCa to development of NEPC (TTNEPC).

PATIENTS AND METHODS

A literature search on NEPC was performed using databases such as MEDLINE and EMBASE. Studies were eligible if outcomes data (NEPCS and/or TTNEPC) were reported in patients with a prior history of PCa and histopathologically confirmed NEPC. NEPCS and TTNEPC were evaluated using the Cox regression model with the robust sandwich estimates of the covariance matrix.

RESULTS

There were 54 eligible publications, contributing 123 patients. The median TTNEPC was 20 months. In multivariable analyses, the Gleason score was significantly associated with shorter TTNEPC (hazard ratio [HR], 1.66; P = .032). The median NEPCS was 7 months. In multivariable analyses, the number of organs with metastatic disease at NEPC was significantly associated with shorter NEPCS (HR, 3.31; P = .001). Type of treatment after NEPC was significantly associated with longer NEPCS, with HRs of 0.66 (radiotherapy v palliative therapy; P = .034), 0.38 (chemotherapy v palliative therapy; P = .018), and 0.29 (chemoradiotherapy v palliative therapy; P = .012), respectively.

CONCLUSION

Treatment-related NEPC is an often under-recognized late manifestation of PCa with poor prognosis. Our study found that Gleason score was the only independent factor contributing to TTNEPC. Once NEPC is diagnosed, type of treatment and the number of organs with metastatic disease were the most important factors related to survival.

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.

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.

Interleukin-1β promotes skeletal colonization and progression of metastatic prostate cancer cells with neuroendocrine features

Despite the progress made in the early detection and treatment of prostate adenocarcinoma, the metastatic lesions from this tumor are incurable. We used genome-wide expression analysis of human prostate cancer cells with different metastatic behavior in animal models to reveal that bone-tropic phenotypes upregulate three genes encoding for the cytokine interleukin-1β (IL-1β), the chemokine CXCL6 (GCP-2), and the protease inhibitor elafin (PI3). The Oncomine database revealed that these three genes are significantly upregulated in human prostate cancer versus normal tissue and correlate with Gleason scores ≥7. This correlation was further validated for IL-1β by immunodetection in prostate tissue arrays. Our study also shows that the exogenous overexpression of IL-1β in nonmetastatic cancer cells promotes their growth into large skeletal lesions in mice, whereas its knockdown significantly impairs the bone progression of highly metastatic cells. In addition, IL-1β secreted by metastatic cells induced the overexpression of COX-2 (PTGS2) in human bone mesenchymal cells treated with conditioned media from bone metastatic prostate cancer cells. Finally, we inspected human tissue specimens from skeletal metastases and detected prostate cancer cells positive for both IL-1β and synaptophysin while concurrently lacking prostate-specific antigen (PSA, KLK3) expression. Collectively, these findings indicate that IL-1β supports the skeletal colonization and metastatic progression of prostate cancer cells with an acquired neuroendocrine phenotype.

Small cell carcinoma of the prostate after high-dose-rate brachytherapy for low-risk prostatic adenocarcinoma

In the present study, we describe an 80-year-old patient who developed prostatic small cell carcinoma (SCC) following high-dose-rate brachytherapy (HDR-BT) for low-risk prostatic adenocarcinoma. The patient received one implant of Ir-192 and 7 fractions of 6.5 Gy within 3.5 days, for a total prescribed dose of 45.5 Gy. A total of 27 months after HDR-BT, the patient complained of difficulty in urinating. His serum prostate-specific antigen (PSA) levels were 3.2 ng/ml. Systemic examination revealed an enlargement of the prostate, urethral stenosis, pelvic lymph node swelling and multiple lung and bone lesions. His serum neuron-specific enolase (NSE) levels were elevated to 120 ng/ml. A prostate needle biopsy was performed for pathological examination. Histologically, there were tumor cells with hyperchromatic nuclei and scant cytoplasm showing a solid or trabecular growth pattern. Immunohistochemically, they were positive for AE1/AE3, CD56 and synaptophysin, and negative for PSA, PAP and CD57. These findings are consistent with SCC of the prostate. A review of the prostate needle biopsy specimen prior to HDR-BT did not reveal any tumor cells positive for chromogranin A, nor synaptophysin. The final diagnosis was SCC of the prostate with local progression, with lung, lymph node and bone metastases. Three cycles of etoposide/cisplatin (EP) were administered. A greater than 50% decrease in the serum NSE levels was observed. However, there was no objective response. Due to the deterioration of the patient's general condition, EP was discontinued. One month later, his serum NSE showed a rapid increase to 210 ng/ml with aggressive local progression and the patient succumbed to the disease 5.5 months after the start of EP therapy.

Pathogenesis of prostatic small cell carcinoma involves the inactivation of the P53 pathway

Small cell neuroendocrine carcinoma (SCNC) of the prostate is a variant form of prostate cancer that occurs de novo or as a recurrent tumor in patients who received hormonal therapy for prostatic adenocarcinoma. It is composed of pure neuroendocrine (NE) tumor cells, but unlike the scattered NE cells in benign prostate and adenocarcinoma that are quiescent, the NE cells in SCNC are highly proliferative and aggressive, causing death in months. In this study, we provide evidence that interleukin 8 (IL8)-CXCR2-P53 (TP53) signaling pathway keeps the NE cells of benign prostate and adenocarcinoma in a quiescent state normally. While P53 appears to be wild-type in the NE cells of benign prostate and adenocarcinoma, immunohistochemical studies show that the majority of the NE tumor cells in SCNC are positive for nuclear p53, suggesting that the p53 is mutated. This observation is confirmed by sequencing of genomic DNA showing p53 mutation in five of seven cases of SCNC. Our results support the hypothesis that p53 mutation leads to inactivation of the IL8-CXCR2-p53 signaling pathway, resulting in the loss of an important growth inhibitory mechanism and the hyper-proliferation of NE cells in SCNC. Therefore, we have identified potential cells of origin and a molecular target for prostatic SCNC that are very different from those of conventional adenocarcinoma, which explains SCNC's distinct biology and the clinical observation that it does not respond to hormonal therapy targeting androgen receptor signaling, which produces short-term therapeutic effects in nearly all patients with prostatic adenocarcinoma.

Next generation sequencing of prostate cancer from a patient identifies a deficiency of methylthioadenosine phosphorylase, an exploitable tumor target

Castrate-resistant prostate cancer (CRPC) and neuroendocrine carcinoma of the prostate are invariably fatal diseases for which only palliative therapies exist. As part of a prostate tumor sequencing program, a patient tumor was analyzed using Illumina genome sequencing and a matched renal capsule tumor xenograft was generated. Both tumor and xenograft had a homozygous 9p21 deletion spanning the MTAP, CDKN2, and ARF genes. It is rare for this deletion to occur in primary prostate tumors, yet approximately 10% express decreased levels of methylthioadenosine phosphorylase (MTAP) mRNA. Decreased MTAP expression is a prognosticator for poor outcome. Moreover, it seems that this deletion is more common in CRPC than in primary prostate cancer. We show for the first time that treatment with methylthioadenosine and high dose 6-thioguanine causes marked inhibition of a patient-derived neuroendocrine xenograft growth while protecting the host from 6-thioguanine toxicity. This therapeutic approach can be applied to other MTAP-deficient human cancers as deletion or hypermethylation of the MTAP gene occurs in a broad spectrum of tumors at high frequency. The combination of genome sequencing and patient-derived xenografts can identify candidate therapeutic agents and evaluate them for personalized oncology.

PC3 is a cell line characteristic of prostatic small cell carcinoma

BACKGROUND

The majority of the prostatic cancers are adenocarcinomas characterized by glandular formation and the expression of luminal differentiation markers androgen receptor (AR) and prostate-specific antigen (PSA). Most adenocarcinomas are indolent and androgen-dependent. Hormonal therapy that inhibits AR signaling produces symptomatic relief in patients with advanced and metastatic adenocarcinomas. Prostatic small cell neuroendocrine carcinoma (SCNC) is a variant form of prostate cancer (PC). In contrast to adenocarcinoma, the tumor cells of SCNC do not form glands and are negative for AR and PSA. SCNC is extremely aggressive and does not respond to hormonal therapy. The purpose of this study was to compare the important and relevant features of two most commonly used PC cell lines, LNCaP and PC3, with prostatic adenocarcinoma and SCNC.

METHODS

Xenograft tumors of LNCaP and PC3 were prepared and compared with human prostatic adenocarcinoma and SCNC for the expression of key signaling molecules by immunohistochemistry and Western blot analysis.

RESULTS

LNCaP cells express AR and PSA and their growth is inhibited by androgen withdrawal, similar to human prostatic adenocarcinoma. PC3 cells do not express AR and PSA and their proliferation is independent of androgen, similar to SCNC. Adenocarcinoma cells and LNCaP cells are negative for neuroendocrine markers and stem cell-associated marker CD44 while SCNC and PC3 cells are positive. LNCaP cells have identical cytokeratin profiles to adenocarcinoma while PC3 cells have cytokeratin profiles similar to SCNC.

CONCLUSION

LNCaP cells share common features with adenocarcinoma while PC3 cells are characteristic of SCNC.

Review of small cell carcinomas of the prostate

Small cell carcinoma of the prostate is a rare neoplasm, with only a few series hitherto reported. A little less than half of the cases are associated with conventional acinar adenocarcinoma, which are usually high grade. Although consensus has not been reached, the majority of patients with small cell neuroendocrine carcinoma of the prostate have advanced disease at diagnosis and disproportionally low PSA levels compared to patients with conventional acinar adenocarcinoma. Treatment consists mainly of chemotherapy associated with surgery. Radiation therapy is reserved for selected cases. This study reviews the most up-to-date information on small cell carcinomas of the prostate.

The relationship of neuroendocrine carcinomas to anti-tumor therapies in TRAMP mice

BACKGROUND

Neuroendocrine differentiation and neuroendocrine carcinoma (NEC) have been linked to androgen deprivation in prostate cancers. No previous study has directly connected neuroendocrine phenotypes to chemotherapy. The pathogenesis of prostatic NEC has not yet been determined.

METHODS

Using the transgenic adenocarcinoma of mouse prostate (TRAMP) model, we studied tumor progression after hormone ablation (castration) and/or chemotherapy (docetaxel), and analyzed the incidence of NEC as a function of the anti-tumor therapies. Non-treated mice were used as controls. Protein expressions in tumor tissues were analyzed by Western blots and immunohistochemistry.

RESULTS

Although all animals developed prostate cancer, no NEC was found in control mice. However, over 30% of the mice that received an anti-tumor therapy developed NEC. A similar incidence of NEC was found in the castration-only and docetaxel-only treatment groups, while a higher incidence was observed in the combined treatment (castration and docetaxel) group. The NEC-bearing mice had smaller tumors in their prostates and lived longer than mice with adenocarcinoma (ADC-only). However, NEC tumors had a higher proliferative index and greater potential for metastasis and drug-resistance, as evidenced by significantly higher expression levels of PCNA, S100A4, and Pgp, but lower levels of E-cadherin. SV40 T-antigen was highly expressed in both NEC and ADC tumors.

CONCLUSIONS

Stress induced by anti-cancer treatments may play a role in NEC development. Although NEC and ADC differ in their expressions of many proteins, a high level of SV40 T-antigen in both tumor types suggest a common progenitor..

CD44 expression is a feature of prostatic small cell carcinoma and distinguishes it from its mimickers

Small cell neuroendocrine carcinoma of the prostate is a rare variant of prostatic cancer that shares morphologic similarity with prostatic adenocarcinoma of Gleason 5 pattern. It has also been considered morphologically and immunohistochemically indistinguishable from small cell neuroendocrine carcinomas of other origins. CD44 is a cell-surface molecule proposed to identify cancer stem/progenitor cells in prostate cancer. We performed immunohistochemical study for CD44 expression in 11 cases of prostatic small cell neuroendocrine carcinoma and compared its patterns of expression with 73 cases of prostatic adenocarcinoma and 47 cases of small cell neuroendocrine carcinomas of other organs. Strong and diffuse membrane staining for CD44 was observed in 100% of the prostatic small cell neuroendocrine carcinomas. In conventional adenocarcinomas of the prostate, positive staining was only seen in rare, scattered tumor cells; and CD44 staining was negative in most of the small cell neuroendocrine carcinomas of nonprostate origin. The difference in CD44 expression between small cell neuroendocrine carcinomas of the prostate and those of other organs are statistically significant (P < .001). Our study demonstrates the utility of immunohistochemical staining for CD44 in distinguishing prostatic small cell neuroendocrine carcinoma from its mimickers including prostatic adenocarcinoma of Gleason 5 pattern and small cell neuroendocrine carcinomas of other organs. CD44 is the first marker that shows a high degree of tissue/organ specificity for small cell neuroendocrine carcinomas. Because CD44 is a putative marker of prostate cancer stem cells, the strong and diffuse expression of CD44 and the lack of expression of prostate luminal differentiation markers androgen receptor and prostatic specific antigen in prostatic small cell neuroendocrine carcinomas suggest that the tumor cells may retain cancer stem cell features.

Small cell carcinoma of the prostate. A morphologic and immunohistochemical study of 95 cases

Small cell carcinoma of prostate is rare, with the literature consisting of case reports and small series. The current work analyzes the morphology and immunohistochemistry of 95 cases of prostatic small cell carcinoma diagnosed at our institution. Specimens included 55 needle biopsies, 27 transurethral resections, 4 radical prostatectomies, and 9 biopsies from metastatic sites (some patients with >1 procedure). Patients ranged in age from 44 to 92 years old (mean: 69 y). Although serum prostate-specific antigen (PSA) in some cases was very high (up to 1896 ng/mL), the median value was only 4.0 ng/mL. Of cases with available information, 33/78 (42%) had a history of usual prostatic adenocarcinoma. The interval between the diagnosis of small cell carcinoma and prior usual prostatic cancer ranged from 1 to 300 months (median 25 mo). Pure small cell carcinoma was seen in 54/95 (57%) of cases with the remaining cases admixed with prostate adenocarcinoma. In cases with adenocarcinoma, there was a sharp demarcation between small cell carcinoma and adenocarcinoma in 20.5% of cases; in the remaining cases there was gradual merging of the 2 components. In mixed cases, small cell carcinoma predominated (median: 80% of the tumor); the Gleason score of the adenocarcinoma was > or =8 in 85% of these cases. In 61 cases (64%), small cell carcinoma was classic "oat cell" morphology with remaining the "intermediate cell" variant. Of the 95 cases: necrosis was seen in 40% (2% to 95% of the tumor); giant bizarre cells in 19%; Indian filing in 21%; rosette formation in 29%; focal vacuolated cytoplasm in 18%; and desmoplasia in 20%. Most (88%) of small cell carcinoma were positive for at least 1 neuroendocrine marker. In the small cell carcinoma component, 14/73 (19%) were positive for PSA, 17/61 (28%) positive for prostein (P501S), and 15/59 (25%) positive for prostate-specific membrane antigen, although often very focally. Stains for thyroid transcription factor-1 were positive in 23/44 (52.3%) cases. In this, the largest study of prostatic small cell carcinoma, we highlight the presence of morphologic features that may result in its underdiagnosis. Other more classic histologic features of small cell carcinoma along with rosettes are critical for its accurate diagnosis. P501S and prostate-specific membrane antigen were better in identifying the prostatic origin of small cell carcinoma than PSA, although the majority (60%) of prostatic small cell carcinomas were negative for all 3 markers.

Sequential occurrence of non-small cell and small cell lung cancer with the same EGFR mutation

We report a case of small cell lung cancer (SCLC) developing after prolonged treatment (more than 2 years) for primary adenocarcinoma of the lung, and we show that both the SCLC and non-small cell lung cancer (NSCLC) tissues obtained from the same site share the same deletion in exon 19 of EGFR. This case suggests that the activating EGFR mutations may confer the pathogenesis of a subset of SCLC.

The pathology of extrapulmonary small cell carcinoma

Extrapulmonary small cell carcinomas (EPSCCs) are uncommon malignant neoplasms with a reported incidence of 0.1% to 0.4% in the United States. Since their first description in 1930, they have been seen in nearly every organ system. Like their more common pulmonary counterparts, EPSCCs are thought to arise from a multipotential stem cell. However, there is recent molecular evidence that small cell elements may arise as a late-stage phenomenon in the genetic progression of more organ-typical carcinomas. The morphologic, immunohistochemical, and ultrastructural features are similar to those described in pulmonary small cell carcinomas (PSCCs). The differential diagnosis of EPSCC includes PSCC, other neuroendocrine tumors, small round blue cell tumors, metastatic melanoma, lymphoma, and poorly differentiated non-small cell carcinomas. Molecular alterations reported to occur in EPSCCs include abnormalities described in PSCC and changes found in carcinomas more typically encountered in the organ from which they arise. In this article we discuss the pathology of EPSCC with a review of theories of histogenesis, sites of occurrence, diagnostic features, differential diagnosis, molecular alterations, and clinical behavior.

Unusual and Underappreciated: Small Cell Carcinoma of the Prostate

In recent years, attention has focused on the prognostic importance of neuroendocrine differentiation in prostate cancer. Focal neuroendocrine differentiation in prostatic adenocarcinoma is a frequent finding. Though controversial, the prevalence of neuroendocrine cells has been correlated with higher-grade malignancy and poor prognosis. As with other small cell tumors, production of ectopic neuropeptides has been reported. The rarity of the disease has precluded prospective randomized trials. Therapeutic regimens have mainly been modeled after those for small cell lung carcinoma. Here we review the literature to identify potential diagnostic, therapeutic, and prognostic factors. Evident from this review is the necessity for further research in the biology of small cell carcinoma progression, in order to improve therapy.

Experience of the treatment with gemcitabine, docetaxel, and carboplatin (GDC) chemotherapy for patients with small-cell carcinoma of the prostate

Small-cell carcinoma of the prostate (SCCP) is a rare entity. Many treatment modalities have been done, but thus far no uniform treatment has been clearly established. We carried out combination chemotherapy with gemcitabine, docetaxel, and carboplatin (GDC) regimen (for two patients with refractory SCCP. Case 1 involved a 53-year-old man diagnosed with SCCP after receiving hormone therapy for prostate cancer (stage D1). Six cycles of GDC chemotherapy was applied. Initially the primary site reduced according with a decline of neuro-specific enolase and with relief of the symptoms; however, bone disease occurred and he died of cancer 13 months after diagnosis of SCCP. Case 2 involved a 69-year-old man complaining of severe anal pain. He underwent a biopsy and a huge prostate tumor showing SCCP was showed. He had pelvic node metastases but no distant lesions, and received four cycles of GDC chemotherapy. He was discharged after receiving subsequent radiotherapy and remained stable for a while; however, he died of possible drug-induced hepatitis. This is the first report of chemotherapy with GDC against patients with SCCP. This regimen raised the possibility that it would intensify the outcome, which had been poorly achieved.

Secondary prostatic adenocarcinoma: A cytopathological study of 50 cases

Positive diagnosis of metastatic prostate adenocarcinoma (PAC) can be made by microscopic examination of the cytologic specimens and immunostaining for prostate-specific antigen (PSA) and prostate acid phosphatase (PAP). Immunohistochemical markers have been known to display negative, weak, or focal staining in poorly differentiated PAC and in patients with prior hormonal and/or radiation therapy. The purpose of this study is to characterize the cytopathology of metastatic PAC as it has not been documented in large series. Fifty cases of metastatic PAC with cytological specimens consisting of 41 fine-needle aspiration biopsies (FNAB), 6 pleural fluid aspirates, and 3 catheterized urine samples were reviewed and correlated with the surgical specimens and the clinical charts. Immunostaining for PSA, PAP, cytokeratin AE1/3, cytokeratin 7 (CK7), cytokeratin 20 (CK20), vimentin, and carcinoembryonic antigen (CEA) was done. Mean patient age was 77 +/- 8 yr; serum PSA, 4.1 +/- 2.3; and primary PAC Gleason score, 8.1 +/- 1.5. Cytologically, the specimens consisted of cell clusters or cell sheets with overlapping uniform hyperchromatic nuclei with or without nucleoli. Twelve cases were not reactive to PSA and PAP and 44 cases displayed negative immunoreactivity to both CK7 and CK20. Carcinoid-like lesions and small cell carcinomas were seen in 4 cases and were misdiagnosed as nonprostatic origin based on the following features: negative immunoreactivity to PSA and PAP with or without positive reactivity to CEA, and different histopathological features when compared with the primary PAC. In addition to the frequency of high-grade PAC, awareness of the negative immunoreactivity to PSA and PAP, the discrepancy in the histopathological patterns between the primary and secondary tumors, especially the frequent neuroendocrine differentiation, are helpful features for the diagnosis of metastases of prostatic origin.

The methyl-CpG-binding protein MECP2 is required for prostate cancer cell growth

The incidence of prostate cancer is increasing in western countries because of population aging. Prostate cancer begins as an androgen-dependent disease, but it can become androgen independent at a later stage or in tumors recurring after an antihormonal treatment. Although many genetic events have been described to be involved in androgen-dependent and/or -independent prostate cancer growth, little is known about the contribution of epigenetic events. Here we have examined the possibility that the methyl-CpG-binding protein MECP2 might play a role in controlling the growth of prostate cancer cells. Inhibition of MECP2 expression by stable short hairpin RNA stopped the growth of both normal and cancer human prostate cells. In addition, ectopic expression of the MECP2 conferred a growth advantage to human prostate cancer cells. More importantly, this expression allowed androgen-dependent cells to grow independently of androgen stimulation and to retain tumorigenic properties in androgen-depleted conditions. Analysis of signaling pathways showed that this effect is independent of androgen receptor signaling. Instead, MECP2 appears to act by maintaining a constant c-myc level during antihormonal treatment. We further show that MECP2-expressing cells possess a functional p53 pathway and are still responsive to chemotherapeutic drugs.

Small cell carcinoma of the prostate expressing prostate-specific antigen and showing syndrome of inappropriate secretion of antidiuretic hormone: an autopsy case report

An autopsy case of primary small cell carcinoma (SCC) of the prostate in a 68-year-old man is reported. The patient was admitted to hospital because of a bloody stool and suspected rectal cancer. However, a diagnosis of prostate cancer was made on the basis of a digital rectal examination, the serum level of prostate-specific antigen, and a needle biopsy of the prostate. The patient also experienced a syndrome of inappropriate secretion of antidiuretic hormone. He died 29 days after admission. At autopsy, the tumor had invaded the rectum, bladder and pelvic peritoneum. Metastases to the heart, vertebrae and lymph nodes were observed. Microscopically, the tumor was composed of small round cells that showed a solid growth pattern. Rosette formations were observed. Immunohistochemically, the tumor cells were positive for a prostatic epithelial marker and neuroendocrine markers. A high level of antidiuretic hormone was detected in the tumor tissue. To our knowledge, this is the first reported case of SCC of the prostate in which both a prostatic epithelial marker and neuroendocrine markers have been found in the same tumor. This finding supports the hypothesis that SCC of the prostate originates from a multipotential stem cell of the prostatic epithelium.

Myc confers androgen-independent prostate cancer cell growth

Prostate cancer is one of the most diagnosed and mortal cancers in western countries. A major clinical problem is the development of androgen-independent prostate cancer (AIPC) during antihormonal treatment. The molecular mechanisms underlying the change from androgen dependence to independence of these tumors are poorly understood and represent a challenge to develop new therapies. Based on genetic data showing amplification of the c-myc gene in AIPC, we studied the ability of c-myc to confer AIPC cell growth. Human androgen-dependent prostate cancer cells overexpressing c-myc grew independently of androgens and presented tumorigenic properties in androgen-depleted conditions. Analysis of signalling pathways by pharmacological inhibitors of the androgen receptor (AR) or by RNA interference directed against AR or c-myc showed that c-myc acted downstream of AR through multiple growth effectors. Thus c-myc is required for androgen-dependent growth and following ectopic expression can induce androgen-independent growth. Moreover, RNA interference directed against c-myc showed that growth of human AIPC cells, AR-positive or -negative, required c-myc expression. Furthermore, we showed that c-myc-overexpressing cells retain a functional p53 pathway and thus respond to etoposide.