Prostate Neuroendocrine Tumors Research Articles

SOX2 expression in the developing, adult, as well as, diseased prostate.

BACKGROUNDSOX2 is a member of SOX (SRY-related HMG box) family of transcription factors.METHODSin this study, we examined the expression of SOX2 in murine and human prostatic specimens by immunohistochemistry.RESULTSwe found that SOX2 was expressed in murine prostates during budding morphogenesis and in neuroendocrine (NE) prostate cancer (PCa) murine models. Expression of SOX2 was also examined in human prostatic tissue. We found that SOX2 was expressed in 26 of 30 benign prostate hyperplasia (BPH) specimens. In these BPH samples, expression of SOX2 was limited to basal epithelial cells. In contrast, 24 of 25 primary PCa specimens were negative for SOX2. The only positive primary PCa was the prostatic NE tumor, which also showed co-expression of synaptophysin. Additionally, the expression of SOX2 was detected in all prostatic NE tumor xenograft lines. Furthermore, we have examined the expression of SOX2 on a set of tissue microarrays consisting of metastatic PCa tissues. Expression of SOX2 was detected in at least one metastatic site in 15 of 24 patients with metastatic castration-resistant PCa; and the expression of SOX2 was correlated with synaptophysin.CONCLUSIONSSOX2 was expressed in developing prostates, basal cells of BPH, as well as prostatic NE tumors.

18F-Fluorodihydroxyphenylalanine PET/CT in Patients with Neuroendocrine Tumors of Unknown Origin: Relation to Tumor Origin and Differentiation

This work was performed to evaluate the performance of (18)F-fluorodihydroxyphenylalanine ((18)F-FDOPA) PET/CT in detecting primary neuroendocrine tumors (NETs) occult on morphologic and functional imaging, in relation to tumor origin and differentiation. A retrospective study of NET patients who were investigated with (18)F-FDOPA PET/CT imaging in 2 academic endocrine tumor centers was conducted. Only patients with negative conventional and somatostatin receptor scintigraphy (SRS) results were studied. Twenty-seven patients were evaluated with (18)F-FDOPA PET/CT, 23 at their initial staging and 4 during their follow-up. The primary occult NET was localized by (18)F-FDOPA PET/CT in 12 patients (overall sensitivity, 44%; 52% in patients evaluated at initial diagnosis), leading to tumor resection in all cases. The primary tumors were distributed and graded as follows: 1 duodenum G2 lesion, 7 ileum G2 lesions, 2 terminal ileum G1 lesions, 1 pancreas G2 lesion, and 1 gallbladder G3 lesion. Patients with positive (18)F-FDOPA PET/CT results had higher values of serum chromogranin A (100% vs. 20%, P = 0.0003), serotonin, or urinary 5-hydroxyindolacetic acid (83% vs. 20%, P = 0.003). Two false-negative results were related to poorly differentiated duodenal and prostatic NETs (G3). (18)F-FDOPA PET/CT showed more metastatic anatomic regions than SRS in 17 patients. (18)F-FDOPA PET appears to be a sensitive functional imaging tool for the detection of primary NETs occult on SRS, especially tumors with a well-differentiated pattern and serotonin secretion.

Abstract IA13: Targeting the dependence of N-Myc on interaction with Aurora-A with small molecules

Abstract Multiple proof-of-principle experiments suggest that targeting members of the Myc family of oncoproteins will have significant therapeutic benefit in human tumors. Deregulated expression of MYCN, one of the three family members implicated in human tumors, is prevalent in both pediatric and adult neuroendocrine tumors. We have shown previously that MYCN-amplified neuroblastoma cells depend on high levels of Aurora-A expression for maintaining N-Myc function. Similarly, Aurora-A and N-Myc bind each other and together drive an oncogenic gene expression program in neuroendocrine prostate tumors. Although stabilization of N-Myc does not require the catalytic activity of Aurora-A, we found that two inhibitors of Aurora-A disrupt the Aurora-A/N-Myc complex and promote degradation of N-Myc via the Fbxw7 ubiquitin ligase. Disruption of the Aurora-A/N-Myc complex inhibits N-Myc-dependent transcription, correlating with tumor regression and prolonged survival in a mouse model of MYCN-driven neuroblastoma, suggesting that Aurora-A is an accessible target that makes destabilization of N-Myc a viable therapeutic strategy. Citation Format: Markus Brockmann, Evon Poon, Louis Chesler, Martin Eilers. Targeting the dependence of N-Myc on interaction with Aurora-A with small molecules. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr IA13.

Abstract 2877: Dual role of mast cells in prostate tumors.

Abstract Prostatic carcinoma is most often a multifocal disease, with areas of localized, well-differentiated adenocarcinomas coexisting with poorly differentiated lesions within the same tumor. Mast cells (MC), classically known as the primary responders in allergic reactions, have been recently indicate of prognostic value in prostate cancer. We have evidence of a dual role of MC in prostate cancer. Within the same human tumor, MC are specifically enriched and degranulated in areas of adenocarcinoma, whereas few around anaplastic foci. This observation has been confirmed in tumors from TRAMP (Transgenic Adenocarcinoma of the Mouse Prostate) mice, and in two novel tumor cells lines, derived from them, phenocopying well and poorly differentiated adenocarcinoma: T1525 and T23, respectively. MC promote the growth of the well-differentiated adenocarcinoma T1525 that does not develop when transplanted into MC-deficient mice, or when MC degranulation is pharmacologically inhibited with sodium cromoglycate. In particular, mast cells are essential for the outgrowth of early-stage tumors due to their matrix metalloproteinase-9 production, become dispensable in advanced-stage, post-epithelial-to-mesenchymal transition, and are protective against neuroendocrine prostate tumor variants. Indeed, pharmacological inhibition or genetic ablation of MC in TRAMP mice results in early development of undifferentiated tumors characterized by marked anaplasia, suggesting that the growth of anaplastic clones may be antagonized by MC. Our data demonstrate that MC can influence the histotype of tumor arising from the prostate and that their targeting may change tumor outcome. As a possible corollary, MC depletion might favor the growth of more undifferentiated and aggressive variants. The common expression of c-Kit by mast cells and neuroendocrine clones suggests a possible competition for the ligand Stem Cell Factor and offers the chance of curing early-stage disease while preventing neuroendocrine tumors using c-Kit-targeted therapy. Citation Format: Mario P. Colombo, Paola Pittoni, Sabina Sangaletti, Claudio Tripodo. Dual role of mast cells in prostate tumors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2877. doi:10.1158/1538-7445.AM2013-2877

Mash1 expression is induced in neuroendocrine prostate cancer upon the loss of Foxa2

Neuroendocrine (NE) prostate tumors and neuroendocrine differentiation (NED) in prostatic adenocarcinomas have been associated with poor prognosis. In this study, we used the TRAMP mouse model that develops NE prostate tumors to identify key factors that can lead to NED. We have previously reported that NE tumors express the forkhead transcription factor, Foxa2, Mash1 (mouse achaete scute homolog-1), as well as Synaptophysin. In TRAMP, the prostatic intraepithelial neoplasia (PIN) first expresses Foxa2 and Synaptophysin, which then progresses to NE cancer. In order to determine if Foxa2 is dispensable for development or maintenance of NE cancer, a conditional knock-out of Foxa2 in TRAMP mice was generated by breeding mice with two floxed alleles of Foxa2 and one copy of Nkx3.1-Cre. Nkx3.1-Cre/Foxa2(loxP/loxP) mice showed loss of Foxa2 expression in embryonic prostatic buds. No expression of Foxa2 was seen in the adult prostate in either conditional null or control mice. Foxa2 is universally expressed in all wild type TRAMP NE tumors, but Mash1 expression is seen only in a few samples in a few cells. With the loss of Foxa2 in the NE tumors of the TRAMP/Nkx3.1-Cre/Foxa2(loxP/loxP) mice, the expression of the pro-neuronal gene Mash1 is upregulated. NE tumors from both the TRAMP control and Foxa2-deficient TRAMP prostate express Synaptophysin and SV40 Large T-antigen, and both show a loss of androgen receptor expression in NE cells. These studies suggest that the TRAMP NE tumors can form in the absence of Foxa2 by an up regulation of Mash1.

The Dark Side of Mast Cell–Targeted Therapy in Prostate Cancer

Tumor development requires accomplices among white blood cells. Other than macrophages, mast cells have been observed to support the outgrowth of certain neoplasias because of their proangiogenic properties. In some tumor settings, however, mast cells may have a protective role, exerted by their proinflammatory mediators. In prostate cancer, no conclusive data on mast cell function were available. Here, we discuss recent work on the role of mast cells in mouse and human prostate cancer, showing that mast cells can behave alternatively as dangerous promoters, innocent bystanders, or essential guardians of tumors, according to the stage and origin of transformed cells. In particular, mast cells are essential for the outgrowth of early-stage tumors due to their matrix metalloproteinase-9 production, become dispensable in advanced-stage, post-epithelial-to-mesenchymal transition, and are protective against neuroendocrine prostate tumor variants. The common expression of c-Kit by mast cells and neuroendocrine clones suggests a possible competition for the ligand Stem cell factor and offers the chance of curing early-stage disease while preventing neuroendocrine tumors using c-Kit-targeted therapy. This review discusses the implications of these findings on the advocated mast cell-targeted cancer therapy and considers future directions in the study of mast cells and their interactions with other c-Kit-expressing cells.

Siah2-Dependent Concerted Activity of HIF and FoxA2 Regulates Formation of Neuroendocrine Phenotype and Neuroendocrine Prostate Tumors

Neuroendocrine (NE) phenotype, seen in >30% of prostate adenocarcinomas (PCa), and NE prostate tumors are implicated in aggressive prostate cancer. Formation of NE prostate tumors in the TRAMP mouse model was suppressed in mice lacking the ubiquitin ligase Siah2, which regulates HIF-1alpha availability. Cooperation between HIF-1alpha and FoxA2, a transcription factor expressed in NE tissue, promotes recruitment of p300 to transactivate select HIF-regulated genes, Hes6, Sox9, and Jmjd1a. These HIF-regulated genes are highly expressed in metastatic PCa and required for hypoxia-mediated NE phenotype, metastasis in PCa, and the formation of NE tumors. Tissue-specific expression of FoxA2 combined with Siah2-dependent HIF-1alpha availability enables a transcriptional program required for NE prostate tumor development and NE phenotype in PCa.

FDG PET-CT demonstration of metastatic neuroendocrine tumor of prostate

BackgroundFDG PET-CT is generally not suitable for diagnosing prostate cancer because of low glycolysis of the tumor cells. Neuroendocrine differentiation of the prostate cancer is often associated with early visceral metastasis and dismal prognosis, which is resulted from changed metabolic and regulatory pathways.Case presentationA case is reported in this paper that FDG PET-CT demonstrates intense uptake of neuroendocrine tumor of the prostate and multiple metastases.ConclusionThere is high glycolysis and strong FDG-avidity of neuroendocrine tumor of the prostate, which is similar to that of high grade of neuroendocrine tumor in other tissue and organs. In some selected cases of prostate neuroendocrine cancer, whole body FDG PET-CT may be helpful for detection of metastatic disease.

Neuroendocrine differentiation in the 12T‐10 transgenic prostate mouse model mimics endocrine differentiation of pancreatic beta cells

Neuroendocrine (NE) prostate cancer develops as an aggressive disease that does not respond to androgen ablation therapy. It has been demonstrated that the paracrine action of NE cells facilitates the progression of androgen dependent adenocarcinoma to an androgen independent state, suggesting a significant role for NE cells during failure of androgen ablation therapy. To investigate the pathways that are involved in NE differentiation of prostate cancer, we have looked at the expression of genes known to be involved in endocrine differentiation of beta-cells in the pancreas. This study has been performed using the NE prostate cancer mouse model (12T-10) and the derivative allograft model (NE-10). Immunohistochemical studies have shown that the neuroendocrine prostate tumors express the transcription factors Foxa2, mouse achaete-scute homolog-1 (mash-1), neurogenin3 (Ngn3) and Nkx2.2. These tumors show a loss of hairy/enhancer of split (Hes-1), a gene that inhibits NE differentiation. Human NE prostate cancers also express Foxa2 and human achaete-scute homolog-1 (HASH-1). These genes are expressed in NE prostate tumors in the similar sequential manner as they appear in a pancreatic beta-cell endocrine differentiation. Foxa2 expression is detected in early prostatic intraepithelial neoplasia (PIN). Mash-1 expression is detected in a few clusters within low grade PIN lesions and Nkx2.2 expression is rarely detected in individual scattered cells within the PIN lesion. Ngn3 and Nkx2.2 frequently appear in the invasive NE cancer. Subsequent NE metastasis to lung and liver show a distinct gene expression pattern. The lung metastasis expresses Ngn3 but does not express Nkx2.2 whereas liver metastases do not express Ngn3 but express Nkx2.2. These results suggest that Ngn3 and Nkx2.2 expression are markers for site-specific metastasis and/or transcriptionally regulated genes that are required for organ-specific metastasis. This study indicates that a pathway similar to pancreatic beta-cell differentiation is involved in NE differentiation of prostate cancer.

Linkage between cellular communications, energy utilization, and proliferation in metastatic neuroendocrine cancers

To identify metabolic features that support the aggressive behavior of human neuroendocrine (NE) cancers, we examined metastatic prostate NE tumors and derived prostate NE cancer (PNEC) cell lines from a transgenic mouse model using a combination of magic angle spinning NMR spectroscopy, in silico predictions of biotransformations that observed metabolites may undergo, biochemical tests of these predictions, and electrophysiological/calcium imaging studies. Malignant NE cells undergo excitation and increased proliferation when their GABA(A), glutamate, and/or glycine receptors are stimulated, use glutamate and GABA as substrates for NADH biosynthesis, and produce propylene glycol, a precursor of pyruvate derived from glycine that increases levels of circulating free fatty acids through extra-NE cell effects. Treatment of nude mice containing PNEC tumor xenografts with (i) amiloride, a diuretic that inhibits Abp1, an enzyme involved in NE cell GABA metabolism, (ii) carbidopa, an inhibitor of dopa decarboxylase which functions upstream of Abp1, plus (iii) flumazenil, a benzodiazepine antagonist that binds to GABA(A) receptors, leads to significant reductions in tumor growth. These findings may be generally applicable: GeneChip data sets from 471 human neoplasms revealed that components of GABA metabolic pathways, including ABP1, exhibit statistically significant increases in their expression in NE and non-NE cancers.

Large Cell Neuroendocrine Carcinoma of Prostate

Neuroendocrine (NE) differentiation in prostate cancer is typically detected by immunohistochemistry as single cells in conventional adenocarcinoma. Prostatic NE tumors, such as carcinoid or small cell carcinoma, are rare and large cell NE carcinoma (LCNEC) is described only in case reports. We identified 7 cases of LCNEC and compiled their clinicopathologic characteristics. In 6 cases, there was a history of adenocarcinoma treated with hormone therapy for a mean of 2.4 years (range: 2 to 3 y). The remaining case was de novo LCNEC. LCNEC was incidentally diagnosed in palliative transurethral resection specimens in 5 cases. The mean patient age at diagnosis with LCNEC was 67 years (range: 43 to 81 y). LCNEC comprised solid sheets and ribbons of cells with abundant pale to amphophilic cytoplasm, large nuclei with coarse chromatin and prominent nucleoli along with brisk mitotic activity and foci of necrosis. In 6 cases, there were foci of admixed adenocarcinoma, 4 of which showed hormone therapy effects. LCNEC was strongly positive for CD56, CD57, chromogranin A, synaptophysin, and P504S/alpha methylacyl CoA racemase. There was strong bcl-2 overexpression, expression of MIB1, and p53 in >50% of nuclei, focally positive staining for prostate specific antigen and prostatic acid phosphatase and negative androgen receptor staining. Follow-up was available for 6 patients, all of who died with metastatic disease at mean of 7 months (range: 3 to 12 mo) after platinum-based chemotherapy. LCNEC of prostate is a distinct clinicopathologic entity that typically manifests after long-term hormonal therapy for prostatic adenocarcinoma and likely arises through clonal progression under the selection pressure of therapy.

Pure Primary Neuroendocrine Tumor of the Prostate: A Rare Entity

An extrapulmonary neuroendocrine tumor arising in the prostate gland has been described in several case series; however, pure and primary prostatic neuroendocrine tumors are very rare, their biologic behavior is not yet well known, and there are only a few reports in the literature describing the clinical features and management of this neoplasm. This article presents the clinicopathologic findings of 2 patients presenting with this disease. The published reports of primary pure neuroendocrine prostate tumors are discussed.

An integrated functional genomics and metabolomics approach for defining poor prognosis in human neuroendocrine cancers

Human neuroendocrine (NE) cancers range from relatively indolent to highly aggressive. In this study, we combine functional genomics with metabolomics to identify features of NE cancers associated with a poor outcome. Analysis of GeneChip datasets of primary prostate tumors, as well as lymph node and liver metastases from transgenic mice with a NE cell cancer, plus derived NE cell lines yielded a signature of 446 genes whose expression is enriched in neoplastic mouse prostatic NE cells. This signature was used for in silico metabolic reconstructions of NE cell metabolism, directed liquid chromatography/tandem MS analysis of metabolites in prostatic NE tumors and cell lines, and analysis of GeneChip datasets of human NE tumors with good or poor prognoses. The results indicate that a distinguishing feature of poor-prognosis NE tumors is a glutamic acid decarboxylase-independent pathway for production of GABA and a pathway for production of imidazole-4-acetate that involves dopa decarboxylase and a membrane-associated amine oxidase, amiloride-binding protein 1. Electrophysiological studies disclosed that imidazole-4-acetate can bind and activate GABA(A) receptors expressed by transformed NE cells, thus providing a previously uncharacterized paradigm for NE tumor cell signaling. Transcriptional, metabolic, and electrophysiologic features of transformed mouse NE cells are also evident in neural progenitor cells.

Prostatic neuroendocrine tumor in multiple endocrine neoplasia Type 2B

We report the unusual occurrence of a neuroendocrine prostatic tumor in two young males with multiple endocrine neoplasia (MEN) 2B. Immunohistochemistry of the tumor markers may help differentiate a primary neuroendocrine prostate tumor from the metastasis of a medullary thyroid carcinoma of poor prognosis. MEN 2B hallmarks (i.e. plasma thyrocalcitonin and urinary metanephrines) may be systematically investigated in neuroendocrine tumors of the prostate, and conversely prostate examination may be performed in the periodic screening of MEN 2B male patients.

RNA interference of achaete-scute homolog 1 in mouse prostate neuroendocrine cells reveals its gene targets and DNA binding sites.

We have previously characterized a transgenic mouse model (CR2-TAg) of metastatic prostate cancer arising in the neuroendocrine (NE) cell lineage. Biomarkers of NE differentiation in this model are expressed in conventional adenocarcinoma of the prostate with NE features. To further characterize the pathways that control NE proliferation, differentiation, and survival, we established prostate NE cancer (PNEC) cell lines from CR2-TAg prostate tumors and metastases. GeneChip analyses of cell lines harvested at different passages, and as xenografted tumors, indicated that PNECs express consistent features ex vivo and in vivo and share a remarkable degree of similarity with primary CR2-TAg prostate NE tumors. PNECs express mAsh1, a basic helix-loop-helix (bHLH) transcription factor essential for NE cell differentiation in other tissues. RNA interference knockdown of mAsh1, GeneChip comparisons of treated and control cell populations, and a computational analysis of down-regulated genes identified 12 transcriptional motifs enriched in the gene set. Affected genes, including Adcy9, Hes6, Iapp1, Ndrg4, c-Myb, and Mesdc2, are enriched for a palindromic E-box motif, CAGCTG, indicating that it is a physiologically relevant mAsh1 binding site. The enrichment of a c-Myb binding site and the finding that c-Myb is down-regulated by mAsh1 RNA interference suggest that mAsh1 and c-Myb are in the same signaling pathway. Our data indicate that mAsh1 negatively regulates the cell cycle (e.g., via enhanced Cdkn2d, Bub1 expression), promotes differentiation (e.g., through effects on cAMP), and enhances survival by inhibiting apoptosis. PNEC cell lines should be generally useful for genetic and/or pharmacologic studies of the regulation of NE cell proliferation, differentiation, and tumorigenesis.

ELEVATED LEVELS OF SERUM SECRETONEURIN IN PATIENTS WITH THERAPY RESISTANT CARCINOMA OF THE PROSTATE

The majority of prostate cancers show some degree of neuroendocrine differentiation. It was previously demonstrated that chromogranin A, a constituent of large dense core vesicles of neuroendocrine cells, is frequently elevated in patients with metastatic prostate cancer. We evaluate the expression of secretoneurin, which is generated by proteolytic processing of secretogranin II (chromogranin C), in patients with prostate disease. Secretoneurin was measured in sera of 16 healthy men whose blood was drawn for prostate cancer screening (controls), and in 9 patients with prostatitis, 19 with benign prostate hyperplasia and 54 with prostate cancer detected by radioimmunoassay. Therapy resistant disease (clinical stage D3) was noted in 20 prostate cancer cases. Serum prostate specific antigen was measured in all patients and controls. In addition, chromogranin A, prostate acid phosphatase and interleukin-6 were determined in patients with D3 prostate cancer. Molecular properties of secretoneurin immunoreactivity were analyzed by gel filtration chromatography followed by radioimmunoassay. Mean secretoneurin was 58.9+/-8 fmol./ml. in patients with therapy resistant prostate cancer. Levels were significantly higher than those measured in sera from controls and patients with prostatitis, benign prostatic hyperplasia and pT2 or pT3 prostate cancer. There was a statistically significant correlation between secretoneurin and chromogranin A in patients with endocrine therapy failure (r = 0.543, p<0.05). There was no correlation between serum secretoneurin and prostate specific antigen, prostate acid phosphatase or interleukin-6. Gel filtration chromatography analysis of sera of 3 patients with D3 prostate cancer revealed a peak of secretoneurin immunoreactivity where intact secretoneurin elutes, thus showing that the processed peptide is circulating in the blood. Secretoneurin is elevated in sera of patients with endocrine therapy refractory prostate cancer. Our results support the concept that neuroendocrine differentiation is associated with prostate cancer progression.

Presence of chromogranins and regulation of their synthesis and processing in a neuroendocrine prostate tumor cell line

Small-cell carcinoma and carcinoid tumors of the prostate display a neuroendocrine phenotype. To some extent, adenocarcinomas of the prostate also express neuroendocrine properties. Prostatic neuroendocrine tumors do not respond to androgen ablation therapy. The regulation of synthesis of chromogranins and their processing into neuropeptides have not yet been studied in neuroendocrine cells of the prostate. We used CRL-5813 cells which were derived from a metastasis from small-cell prostate cancer for studies on steroid receptor expression and chromogranin processing. The expression of steroid receptor mRNA in CRL-5813 cells was examined by polymerase chain reaction. The synthesis and secretion of chromogranin- and secretogranin II-derived peptides were investigated by radioimmunoassays and high-performance liquid chromatography in untreated cells and in cells treated with the protein kinase A activator forskolin or basic fibroblast growth factor (bFGF). cDNA fragments for alpha-estrogen receptor and androgen receptor but not for beta-estrogen receptor, progesterone receptor, and glucocorticoid receptor were amplified from CRL-5813 cells. These cells were found to contain typical markers of large dense-core vesicles, i.e., chromogranins A and B and secretogranin II. Forskolin significantly stimulated the synthesis and secretion of the chromogranin B-derived peptide PE-11 and the secretogranin II-derived secretoneurin. bFGF significantly induced PE-11 protein levels in cell extracts. CONCLUSIONS. Our results demonstrate the expression of typical large dense-core vesicle proteins, i.e., chromogranins, in a small-cell prostate cancer cell line and their upregulation by a protein kinase A activator and, in part, by bFGF.

Presence of chromogranins and regulation of their synthesis and processing in a neuroendocrine prostate tumor cell line

Presence of chromogranins and regulation of their synthesis and processing in a neuroendocrine prostate tumor cell line