The prognostic significance of neuroendocrine differentiation in prostatic malignancy is controversial, but the results of recent studies with markers such as chromogranin A and neurone-specific enolase suggest that neuroendocrine differentiation, as reflected by increased tissue expression or blood concentrations of these neuroendocrine secretory products, is associated with a poor prognosis, tumour progression, and androgen independence. As all malignant neuroendocrine cells are devoid of androgen receptors and the expression of neuroendocrine cells is not suppressed by androgen ablation, clonal propagation of androgen receptor-negative neuroendocrine cells may have an important role in the development of androgen-independent prostatic carcinoma. This has significant implications for the treatment of prostate cancer, because several of the hormones that are secreted by neuroendocrine differentiated, malignant prostatic cells are potential candidates for use in drug treatment. A limited number of hormones have been tested in this context, in particular somatostatin, bombesin, and serotonin. As there is currently no successful treatment for differentiated prostate cancer, new therapeutic procedures and trials need to be developed to test drugs based on neuroendocrine hormones or their antagonists.
P A Abrahamsson
A H Bootsma, C H J van Eijck, L J Hofland, and S W J Lamberts
C Péqueux, B P Keegan, M-T Hagelstein, V Geenen, J-J Legros, and W G North
Introduction As a basic component of oncogenesis, neuroendocrine tumour cells usually develop very potent autocrine/paracrine signalling pathways that play a crucial part in the dysregulation of cellular growth ( Hanahan & Weinberg
J K Ramage, A H Davies, and EORTC Quality of Life Group
Quality of life is multi-dimensional, including issues relating to symptoms from the disease but also social, emotional, functional and financial domains. Debate remains on the true definition of quality of life and its measurement. Quality of life measurements are best done by patients themselves, although, in some situations a proxy such as carer or relative can be substituted. Healthcare workers can over- or underestimate overall quality of life. Currently used devices for measuring quality of life in cancer include the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30, which is a generic tool for all cancers and which requires the use of add-on modules for specific cancers. We are developing a separate module for carcinoid/neuroendocrine tumours, in accordance with the EORTC guidelines on module development, which will be translated into five languages and will be available for use throughout Europe.
U Meyer-Pannwitt, K Kummerfeldt, G Froeschle, V A Dorss, and R Klapdor
Mark P Labrecque, Joshi J Alumkal, Ilsa M Coleman, Peter S Nelson, and Colm Morrissey
The use of androgen deprivation therapy and second line anti-androgens in prostate cancer has led to the emergence of tumors employing multiple androgen receptor (AR)-dependent and AR-independent mechanisms to resist AR targeted therapies in castration-resistant prostate cancer (CRPC). While the AR signaling axis remains the cornerstone for therapeutic development in CRPC, a clearer understanding of the heterogeneous biology of CRPC tumors is needed for inno-vative treatment strategies. In this review, we discuss the characteristics of CRPC tumors that lack AR activity and the temporal and spatial considerations for the conversion of an AR-dependent to an AR-independent tumor type. We describe the more prevalent treatment-emergent phenotypes aris-ing in the CRPC disease continuum, including amphicrine, AR-low, double-negative, neuroendo-crine and small cell phenotypes. We discuss the association between the loss of AR activity and tumor plasticity with a focus on the roles of transcription factors like SOX2, DNA methylation, alterna-tive splicing, and the activity of epigenetic modifiers like EZH2, BRD4, LSD1, and the nBAF complex in conversion to a neuroendocrine or small cell phenotype in CRPC. We hypothesize that only a subset of CRPC tumors have the propensity for tumor plasticity and conversion to the neuroendo-crine phenotype and outline how we might target these plastic and emergent phenotypes in CRPC. In conclusion, we assess the current and future avenues for treatment and determine that the heter-ogeneity of CRPCs lacking AR activity will require diverse treatment approaches.
S K Kang, K-C Choi, H-S Yang, and P C K Leung
Gonadotrophin-releasing hormone (GnRH) functions as a key neuroendocrine regulator of the hypothalamic-pituitary-gonadal axis. In addition to the hypothalamus and pituitary gland, GnRH and its receptor have been detected in other reproductive tissues including the gonads, placenta and tumours arising from these tissues. Recently, a second form of GnRH (GnRH-II) and type II GnRH receptor have been found in normal ovarian surface epithelium and neoplastic counterparts. The two types of GnRH may play an important role as an autocrine/paracrine regulator of reproductive functions and ovarian tumour growth. In this review, the distribution and potential roles of GnRH-I/-II and their GnRH receptors in the ovarian cells and ovarian cancer will be discussed.
F W F Hanna, C F Johnston, J E S Ardill, and K D Buchanan
Background: Salmon calcitonin (sCT) injection into rats has been reported to induce pituitary tumours. We have demonstrated the co-existence, in the rat-derived α-TSH cell line, of an sCT-like peptide, as well as a receptor for sCT.
Aim: This was to investigate the possible existence of sCT-like immunoreactivity (sCT-LI) in human neuroendocrine tumours.
Methods: A collection of human neuroendocrine tumours was tested, using a highly specific antibody for sCT. Immunostaining was abolished by preabsorption with sCT at concentrations higher than 1 μg/ml. However, as immunofluorescence was still obvious at the highest concentration (100 pg/ml) of hCT employed, any significant cross-reactivity was excluded.
Results: Of the human pituitary null cell tumours studied, positive staining was obtained in 2 out of 12, suggesting a similarity between the rat and human pituitary glands. None of the other pituitary tumours tested showed sCT-LI (these included 8 corticotroph tumours, 6 prolactinomas and 2 somatotroph tumours).
This work was extended to medullary thyroid carcinomas (MTCs) and a further group of neuroendocrine tumours, looking for the specificity of this sCT-LI among the various APUDomas.
All the tested MTCs (n=14) expressed sCT-LI, while none of the examined phaeochromocytomas (n=23), intestinal carcinoids (n=14), lung carcinoids (n=16), stomach carcinoids (n=2), rectal carcinoids (n=2), gastrinomas (n=4), insulinomas (n=12), oat cell carcinomas (n=7), carotid body tumours (n=9), VIPomas (n=3), or a glucagonoma (n=1) expressed sCT-LI. This indicates that this sCT-LI might be unique to MTC (and possibly the pituitary).
Conclusion: The possible existence of the most potent form of CT may provide an explanation for the vasomotor disturbances in MTC and may be a potential new tumour marker for MTC. Phylogenetically, the presence of a lower form of CT in mammalian tissues would give an insight into the conservation of the CT peptide family in evolution.
Endocrine-Related Cancer (1997) 4 191-195
J T Arnold and J T Isaacs
The acquisition of an androgen-independent phenotype by prostate cancer cells is presently a death sentence for patients. In order to have a realistic chance of changing this outcome, an understanding of what drives the progression to androgen independence is critical. We review here a working hypothesis based on the position that the development of androgen-independent epithelial cells is the result of a series of cellular and molecular events within the whole tissue that culminates in the loss of normal tissue-maintained growth control. This tissue includes the epithelial and stromal cells, the supporting extracellular matrix and circulating hormones. This review discusses the characteristics of these malignant cells, the role of stromal cells involved in growth and the differentiation of epithelial cells, and the role of the extracellular matrix as a mediator of the phenotypes of stromal and epithelial cells. In addition, environmental, neuroendocrine and immune factors that may contribute to disturbance of the fine balance of the epithelial-stromal-extracellular matrix connection are considered. While the goal of many therapeutic approaches to prostate cancer has been androgen ablation or targeting the androgen receptor (AR) of epithelial cells, these therapies become ineffective as the cells progress beyond dependence on androgen for growth control. Twenty years ago Sir David Smithers debated that cancer is the result of loss of tolerance within tissues and the organizational failure of normal growth-control mechanisms. This is precipitated by prolonged or abnormal demands for regeneration or repair, rather than of any inherent disorder peculiar to each of the individual components involved. He wrote "It is not the cell itself that is disorderly, but its relationship with the rest of the tissue". We have gained significantly large amounts of precise data on the effects of androgenic ablation on cancerous prostate cells and on the role of the AR in prostate cancer. The need has come to compile this information towards a perspective of dysregulation of tissue as a whole, and to develop experimental systems to address this broader perspective to find and develop therapies for treatment and prevention.
Vanessa D'Antongiovanni, Serena Martinelli, Susan Richter, Letizia Canu, Daniele Guasti, Tommaso Mello, Paolo Romagnoli, Karel Pacak, Graeme Eisenhofer, Massimo Mannelli, and Elena Rapizzi
that tumor microenvironment plays a pivotal role in modulating cell metabolism, tumor growth and progression ( Rapizzi et al. 2015 ). Solid tumors are very complex tissues, comprising of not only cancer cells but also non-malignant stromal cells