The prognostic value of neuroendocrine differentiation in adenocarcinoma of the prostate in relation to progression of disease after endocrine therapy

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

PURPOSE

Neuroendocrine cells are ubiquitous but uncommon in benign and neoplastic prostate epithelium, and they are considered important for regulating cell growth and differentiation. The predictive value of neuroendocrine immunoreactivity for patient outcome after radical prostatectomy is uncertain. In this study we determined the expression of 2 important neuroendocrine markers, chromogranin and serotonin, in benign epithelium, primary prostate cancer and lymph node metastases, and correlated cellular expression with patient outcome.

MATERIALS AND METHODS

We studied 196 patients with node positive prostate adenocarcinoma who underwent bilateral pelvic lymphadenectomy and radical prostatectomy at Mayo Clinic between 1987 and 1992. Mean followup was 6.8 years (range 0.3 to 11). The cellular expression of chromogranin and serotonin in matched samples of benign tissue, primary prostate cancer and lymph node metastases from the same patients was evaluated by immunohistochemical staining using commercially available monoclonal antibodies. Results were correlated with patient age, pathological findings (Gleason score, DNA ploidy and cancer volume) and patient outcome, including clinical progression, cancer specific and all cause survival.

RESULTS

Chromogranin immunoreactivity was greater in benign prostatic epithelium and primary cancer cases (99% each) than in those of lymph node metastases (37.5%) (pairwise comparisons with metastases p <0.001). The mean incidence of immunoreactive cells in benign epithelium, primary cancer and metastases was 6% (median 5%), 6% (median 3%) and 2.2% (median 0%), respectively. Serotonin immunoreactivity was greatest in benign prostate epithelium cases (98.5%) with less in primary cancer (95%) and lymph node metastases (21.5%) (pairwise comparisons p <0.001). The mean incidence of immunoreactive cells in benign epithelium, primary cancer and metastases was 2.2% (median 3%), 2.4% (median 2%) and 0.4% (median 0%), respectively. Chromogranin expression was invariably greater than that of serotonin for all 3 diagnostic categories (p <0.0001). There was a marginally significant positive trend in the level of chromogranin expression in benign prostatic epithelium and systemic progression (p = 0.05) but no significant association with cancer specific or all cause survival (p >0.1). No significant association was observed of chromogranin expression in primary cancer or lymph node metastases with any patient outcomes (p >0.1). There was a significant association of the level of serotonin expression in benign prostatic epithelium with cancer specific survival (p = 0.03) but no significant association with systemic progression or all cause survival (p > 0.1). There were positive trends in the association of serotonin immunoreactivity in primary cancer with systemic progression (p = 0.09) and cancer specific survival (p = 0.05) but not with all cause survival (p >0.1). No significant association was observed of serotonin expression in lymph node metastases with any patient outcomes (p >0.1).

CONCLUSIONS

Benign prostatic epithelium and primary prostate cancer express a significantly greater number of chromogranin and serotonin immunoreactive cells than lymph node metastases, suggesting that decreased expression of neuroendocrine markers is involved in cancer progression. However, neuroendocrine expression was marginally useful for predicting the outcome in patients with node positive prostate cancer treated with radical prostatectomy.

A neuroendocrine/small cell prostate carcinoma xenograft-LuCaP 49

The late stages of progression of prostate carcinoma are typically characterized by an androgen-insensitive, rapidly proliferative state. Some late-stage tumors are composed predominantly of neuroendocrine cells. Virtually no animal models of a neuroendocrine/small cell variant of prostate carcinoma are available for experimental studies. We report a human neuroendocrine/small cell prostate carcinoma xenograft that was developed from a nodal metastasis of a human prostate carcinoma and that has been propagated as serial subcutaneous implants in severe combined immunodeficient mice for >4 years. Designated LuCaP 49, all tumor passages exhibit a neuroendocrine/small cell carcinoma phenotype-insensitivity to androgen deprivation, expression of neuroendocrine proteins, lack of expression of prostate-specific antigen or androgen receptor, and an unusually rapid growth (a doubling time of 6.5 days) for prostate cancer xenografts. Genetically this tumor exhibits loss of heterozygosity for the short arm of chromosome 8 and has a complex karyotype. This xenograft should prove to be useful in the investigation of mechanisms underlying the androgen-insensitive state of progressive prostate carcinoma.

Androgen ablation promotes neuroendocrine cell differentiation in dog and human prostate

BACKGROUND

Mechanisms triggering prostatic NE differentiation are poorly understood. Since dog and man naturally develop prostatic proliferative diseases with age, our objectives were to confirm the presence of NE cells in the dog prostate and test their hormonal regulation in both species.

METHODS

Serotonin staining was examined by immunohistochemistry in 37 dog prostates: 17 from intact and 20 from castrated animals. In intact dogs, 9 prostates were normal and 8 hyperplastic. In the castrated group, 6 dogs were left untreated while androgens and estrogens were administered to 7 dogs, each. Human prostates were from 48 prostate cancer patients; half of them were submitted to androgen ablation prior to prostatectomy. The density of serotonin-positive NE cells was expressed relatively to the number of acini.

RESULTS

Serotonin-positive NE cells were morphologically similar in dog and human prostates and identified in all groups, independent of the hormonal status. NE cell densities were within the same range in normal and hyperplastic dog prostates but significantly higher after castration. Androgens and estrogens after castration restored NE cell density to normal values and induced luminal differentiation and basal metaplasia, respectively. In human, the density of serotonin-positive NE cells was also significantly higher in benign glands after androgen ablation.

CONCLUSIONS

The dog is a suitable animal model and mimics the human, since androgen ablation favored prostatic NE differentiation in both species. The down-regulation elicited by steroids suggests that the process may be reversible and hormonally-repressed.

Relationship between neuroendocrine features and prognostic parameters in human prostate adenocarcinoma

PURPOSE

The biological behaviour of prostate cancer is highly variable and prediction by the commonly employed prognostic parameters is not sufficient. The concept of neuroendocrine (NE) differentiation in prostate adenocarcinoma has recently received increasing attention due to possible implications for prognosis and therapy.

MATERIALS AND METHODS

Core needle biopsies from 142 newly diagnosed patients were immunohistochemically examined for the coexistence of NE differentiation using an antibody against chromogranin A (CgA). Circulating CgA was available in 106 of these patients.

RESULTS

NE differentiation was found in 64 (45.1%) tumors. Among them 29 (20.4%) had CgA positive cells scattered or focally distributed in less than 5% per mm3 of tumor tissues, 26 (18.3%) between 5% and 10% and 9 (6.4%) more than 10%, respectively. There was a significant correlation between the extent of NE features and either Gleason score (P < 0.01) or stage of disease. Circulating CgA but not PSA correlated with immunohistochemical CgA (P < 0.03) particularly in metastatic cases.

CONCLUSIONS

These data support the concept that NE differentiation in human prostate cancer has a negative prognostic significance. Circulating CgA levels reflect immunohistochemical findings.

Different profiles of neuroendocrine cell differentiation evolve in the PC-310 human prostate cancer model during long-term androgen deprivation

BACKGROUND

Neuroendocrine (NE) cells are androgen-independent cells and secrete growth-modulating peptide hormones via a regulated secretory pathway (RSP). We studied NE differentiation after long-term androgen withdrawal in the androgen-dependent human prostate cancer xenograft PC-310.

METHODS

Tumor-bearing nude mice were killed at 0, 2, 5, 7, 14, 21, 47, 84, and 154 days after castration. The half-life of the PC-310 tumor was 10 days, with a stable residual tumor volume of 30--40% after 21 days and longer periods of androgen deprivation.

RESULTS

Proliferative activity and prostate-specific antigen serum levels decreased to zero after castration, whereas cell-cycle arrest was manifested by increased p27(kip1) expression. A temporary downregulation of androgen receptor (AR) expression was noted after androgen deprivation. The expression of chromogranin A, secretogranin III, and secretogranin V (7B2) increased 5 days after castration and later. Subsequently, pro-hormone convertase 1 and peptidyl alpha--amidating monooxygenase as well as vascular endothelial growth factor were expressed from 7 days after castration on. Finally, such growth factors as gastrin-releasing peptide and serotonin were expressed in a small part of the NE cells 21 days after castration, but strong expression was induced late during androgen deprivation, that is, 84 and 154 days after castration, respectively.

CONCLUSIONS

Androgen deprivation of the NE-differentiated PC-310 model induced the formation of NE-differentiated AR(minus sign) and non-NE AR(+) tumor residues. The NE-differentiated cells actively produced growth factors via an RSP that may lead to hormone-refractory disease. The dormant non-NE AR(+) tumor cells were shown to remain androgen sensitive even after long-term androgen deprivation. In the PC-310 xenograft, time-dependent NE differentiation and subsequent maturation were induced after androgen depletion. The androgen-dependent PC-310 xenograft model constitutes an excellent model for studying the role of NE cells in the progression of clinical prostate cancer.

Neuroendocrine differentiation and prognosis in breast adenocarcinoma

AIMS

Neuroendocrine differentiation has been detected, and its prognostic value studied, in a number of common human carcinomas. To date there are few detailed studies examining its relevance in breast carcinoma. In this study we evaluate the frequency and prognostic importance of neuroendocrine differentiation in breast adenocarcinoma.

METHODS AND RESULTS

The presence of neuroendocrine differentiation, defined as positive reactivity for three markers, neuron-specific enolase (NSE), chromogranin A and/or synaptophysin, has been evaluated in 99 patients with primary operable breast cancer using standard immunocytochemical techniques. A consecutive cohort of patients were selected from the Nottingham/Tenovus series. Comprehensive patient and tumour records have been maintained, and patients were followed up according to a defined protocol. Eighteen cases were positive for NSE, 10 for chromogranin A and 13 for synaptophysin. Eleven percent were positive with more than one neuroendocrine marker. No significant association was found between neuroendocrine differentiation and tumour size, grade, stage or the prevalence of vascular invasion. There was no significant difference in either overall or disease-free survival between patients with or without neuroendocrine differentiation.

CONCLUSIONS

In this study we confirm that neuroendocrine differentiation can be identified in a subset (10-18%) of human breast carcinomas. This phenomenon appears to have no relationship to established prognostic factors or patient outcome.

Neuroendocrine tumor markers

Tumor markers used in the diagnosis and follow-up of patients with neuroendocrine tumors are in most instances not specific for a given tumor and circulate under normal conditions in the serum, making their use as an early diagnostic tool difficult (low sensitivity). By combining hormone measurements with tissue responsiveness, demonstrations of inappropriate secretions of PTH, insulin, and gastrin during hypercalcemia, hypoglycemia, and hyperacidity, respectively, become highly sensitive and specific diagnostic tests. The application of polyclonal antibodies in RIAs of hormones, such as ACTH, insulin, and gastrin, increase the diagnostic level of hormone measurements in patients with neuroendocrine tumors. Other markers, such as chromogranin A, neuron-specific enolase, and alpha-subunit, as well as peptide receptor visualization, are of increasing importance in the diagnosis and follow-up of neuroendocrine and non-neuroendocrine tumors.

Neuroendocrine cells in human prostate over-express the anti-apoptosis protein survivin

BACKGROUND

Neuroendocrine (NE) differentiation may be related to the growth and progression of prostate cancer, especially androgen-insensitive tumors. Recently the over-expression of a new anti-apoptosis protein, survivin, has attracted attention for its potential implication in many human cancers. The fact that NE cells in prostate are bcl-2 negative prompted us to investigate if the prostatic NE cells over-express survivin.

METHODS

Double immunohistochemical staining and immunofluorescence of chromogranin A (CgA) and survivin were performed in 57 patients with localized prostate cancer who underwent radical prostatectomy. The terminal deoxynucleotidyl transferase (TDT)-mediated dUTP-digoxigenin nick end-labeling (TUNEL) method was used for apoptosis detection in three prostate cancer specimens with NE differentiation. The relationship between NE differentiation and clinicopathological characteristics, disease progression as well as patient survival, were analyzed retrospectively.

RESULTS

It was found that NE cells in both benign and malignant prostate tissues over-expressed the anti-apoptosis protein survivin. While apoptosis was detected in non-NE epithelial cells, all NE cells were negative for apoptosis detection. During the period of follow-up, 17 (63%) of 27 patients with NE differentiation had prostate cancer progression, while 12 (40%) of 30 patients without NE differentiation had systemic prostate cancer progression. 10 (37%) of 27 patients with NE differentiation died from prostate cancer during the period of follow up, while 6 (20%) of 30 patients without NE differentiation died from prostate cancer. However, none of these characteristics reached statistical significance, probably because of the small number of cases enrolled.

CONCLUSIONS

This study discovers that all the prostatic NE cells express the new anti-apoptosis protein survivin. This provides a strong molecular basis for the hypothesis that NE cells may endure stressful conditions and escape from apoptosis. While our results suggest a trend of NE differentiation with poorer prognosis, the prognosis implication cannot be concluded due to our small sample size.

Prognostic significance of neuroendocrine differentiation, proliferation activity and androgen receptor expression in prostate cancer

Androgen, acting via the androgen receptor (AR), is associated with the development and progression of prostate cancer. Anti-androgen therapy is widely used to manage prostate cancer. However, the conversion of the tumor from a hormone-sensitive to a hormone-insensitive status causes such therapy to fail. Several mechanisms have now been put forward for this conversion, including neuroendocrine (NE) differentiation of the tumor cells. In this study, we evaluated the prognostic significance of tumor-cell proliferation activity, NE differentiation and AR expression. Formalin-fixed, paraffin-embedded sections were prepared from 42 patients with adenocarcinoma of the prostate. Using antibodies to AR, the Ki-67 antigen (MIB-1), chromogranin A and synaptophysin, immunohistochemical expression of AR, tumor proliferation activity and NE differentiation were analyzed. Our study revealed that AR expression was significantly lower in adenocarcinoma (52.2 +/- 27.1%) than in non-tumorous prostate tissue (68.3 +/- 18.3%; P < 0.001). NE differentiation was found in 50% of the tumors, which was correlated with the Gleason score (P < 0.05). An univariate analysis revealed a significant correlation between progression-free survival with both AR expression (P < 0.01) and proliferation activity (P < 0.001). NE differentiation was not a prognostic factor in this study.

Prognostic value of neuroendocrine serum markers and PSA in irradiated patients with pN0 localized prostate cancer

BACKGROUND

The prognosis of patients with localized prostate cancer depends on clinical stage, histological grade, and pretreatment prostate-specific antigen (PSA). We evaluated the additional prognostic impact of serum levels of neuron-specific enolase (NSE) and chromograninA (CgA) after curative radiotherapy and the importance of serum PSA, analyzed 3 months after irradiation.

METHODS

From 1988 to 1995, 161 patients with localized T1-4, pN0M0, prostate adenocarcinoma were treated with external radiation (66Gy, 2Gy/5 fractions per week). Frozen serum samples were assessed for CgA, NSE, and PSA before and 3 months after radiotherapy. CgA was analyzed in only 100 patients. NSE and CgA were determined by a immunometric assay. Total PSA was measured by a time-resolved fluoro-immunometric assay.

RESULTS

Prior to radiotherapy CgA was elevated in 16 of 100 patients, and NSE was elevated in 33 of the 161 patients. There was no association between grade, T category or pretreatment PSA and the levels of neuroendocrine markers. Pretreatment-elevated serum NSE, but not initial CgA, identified patients with an unfavorable prognosis. A < 50% reduction of PSA 3 months after radiotherapy was associated with decreased failure-free 10 years urvival. Multivariate analysis demonstrated an increased risk of failure for patients with elevated pretreatment NSE and PSA values, T3 category, and decline of PSA less than 50% 3 months after radiotherapy. The presence of none or several risk factors (1-4) defined clearly separable groups.

CONCLUSIONS

Together with T category and pretreatment serum PSA values, serum NSE values before radiotherapy and decrease of serum PSA 3 months after radiotherapy represent easily assessable prognostic parameters in patients undergoing curative radiation treatment for prostate cancer.

Neuroendocrine differentiation is not prognostic of failure after radical prostatectomy but correlates with tumor volume

OBJECTIVES

To study neuroendocrine (NE) tumor cell differentiation in prostate cancer in relation to failure after radical prostatectomy.

METHODS

Radical prostatectomy specimens from 103 of 111 patients randomized to 3-month neoadjuvant luteinizing hormone-releasing hormone-analogue treatment (neoadjuvant group) or to surgery alone (control group) were available for analysis. Immunohistochemistry using antibodies to chromogranin A (CGA) enabled detection of tumor cells with NE differentiation. NE differentiation was scored as NE-negative (0 to 1+) or NE-positive (2 to 3+). The number of CGA-positive cells/cm(2) tumor area on the slides was assessed in a separate analysis. The patients were followed up for 39 months after surgery, and a prostate-specific antigen value of 0.5 ng/mL or greater in two consecutive blood samples was considered biochemical failure.

RESULTS

Kaplan-Meier analysis stratified for neoadjuvant hormonal treatment showed the failure rate to be significantly greater among those with NE-positive tumors than among those with NE-negative tumors. However, the number of CGA-positive cells/cm(2) was not a variable of prognostic significance. Instead, both NE differentiation and the CGA-positive cell count correlated with the tumor area on the slides (P = 0.0001). Multivariate analysis revealed the tumor area on the slide (P <0.0001) and positive surgical margins (P = 0.03) to be the only significant predictors of biochemical failure.

CONCLUSIONS

The extension of NE differentiation in prostate cancer correlates with tumor volume and is not an independent prognostic factor of failure after radical prostatectomy.

Prognostic factors in prostate cancer. College of American Pathologists Consensus Statement 1999

BACKGROUND

Under the auspices of the College of American Pathologists, a multidisciplinary group of clinicians, pathologists, and statisticians considered prognostic and predictive factors in prostate cancer and stratified them into categories reflecting the strength of published evidence and taking into account the expert opinions of the Prostate Working Group members.

MATERIALS AND METHODS

Factors were ranked according to the previous College of American Pathologists categorical rankings: category I, factors proven to be of prognostic importance and useful in clinical patient management; category II, factors that have been extensively studied biologically and clinically but whose importance remains to be validated in statistically robust studies; and category III, all other factors not sufficiently studied to demonstrate their prognostic value. Factors in categories I and II were considered with respect to variations in methods of analysis, interpretation of findings, reporting of data, and statistical evaluation. For each factor, detailed recommendations for improvement were made. Recommendations were based on the following aims: (1) increasing uniformity and completeness of pathologic evaluation of tumor specimens, (2) enhancing the quality of data collected pertaining to existing prognostic factors, and (3) improving patient care.

RESULTS AND CONCLUSIONS

Factors ranked in category I included preoperative serum prostate-specific antigen level, TNM stage grouping, histologic grade as Gleason score, and surgical margin status. Category II factors included tumor volume, histologic type, and DNA ploidy. Factors in category III included perineural invasion, neuroendocrine differentiation, microvessel density, nuclear roundness, chromatin texture, other karyometric factors, proliferation markers, prostate-specific antigen derivatives, and other factors (oncogenes, tumor suppressor genes, apoptosis genes, etc).

Regressive changes and neuroendocrine differentiation in prostate cancer after neoadjuvant hormonal treatment

BACKGROUND

We studied the extent of neuroendocrine (NE) tumor cell differentiation and its relation to regressive changes in prostate cancer after 3-month hormonal treatment.

METHODS

Radical prostatectomy specimens from 103 patients, randomized to 3-month neoadjuvant LH-RH-analogue treatment (neoadjuvant group) or to surgery alone (control group), were available for analysis. The effects of hormonal treatment in terms of positive surgical margins, the degree of histopathological changes, and tumor cell proliferation were evaluated in relation to NE-differentiation assessed with antibodies against chromogranin A (CGA).

RESULTS

Both the number of CGA-positive cells/cm(2) (P < 0.003) and the proportion of NE-positive tumors (P = 0.07) were greater in the neoadjuvant group than in the control group. No correlation existed between NE-differentiation and the effects of the neoadjuvant hormonal treatment; nor did NE-differentiation correlate to the decrease in serum PSA.

CONCLUSIONS

Neuroendocrine differentiation in prostate cancer increases after 3 months of neoadjuvant hormonal treatment but does not correlate to the effects of hormonal treatment.

Androgen-independent growth is induced by neuropeptides in human prostate cancer cell lines

BACKGROUND

Androgen-independent growth leads to progressive prostate cancer after androgen-ablation therapy. This may be caused by altered specificity of the androgen receptor (AR), by ligand-independent stimulation of the AR, or by paracrine growth modulation by neuropeptides secreted by neuroendocrine (NE) cells.

METHODS

We established and characterized the androgen-independent FGC-DCC from the androgen-dependent LNCaP fast growing colony (FGC) cell line. The androgen-independent DU-145, FGC-DCC, and PC-3, and the androgen-dependent LNCaP and PC-346C cell lines were used to study growth modulation of gastrin-releasing peptide (GRP), calcitonin (CT), serotonin (5-HT), and vasoactive intestinal peptide (VIP) by (3)H-thymidine incorporation. Specificity of the growth-modulating effects was tested with the anti-GRP monoclonal antibody 2A11 and induction of cAMP by neuropeptides.

RESULTS

Androgen-independent growth stimulation by neuropeptides was shown in DU-145 and PC-346C. 2A11 inhibited GRP-induced (3)H-thymidine incorporation in DU-145 and PC-346C and inhibited proliferation of the FGC-DCC and PC-3 cell lines. With some exceptions, cAMP induction paralleled growth stimulation. Dideoxyadenosine (DDA) inhibited the GRP-induced growth effect in DU-145 and PC-346C, whereas oxadiazoloquinoxaline-1-one (ODQ) had no effect on (3)H-thymidine incorporation. None of the neuropeptides stimulated growth of LNCaP, FGC-DCC, or PC-3.

CONCLUSIONS

GRP-induced growth of DU-145 and PC-346C was specific and cAMP-mediated. Androgen-independent growth of FGC-DCC cells was mainly due to an induction of Bcl-2 expression and possibly through the activation of an autocrine and NE-like pathway, as has been shown also for the PC-3 cell line. Growth induction of non-NE cells by neuropeptides could be a possible role for NE cells in clinical prostate cancer.

Prostate cancer and neuroendocrine differentiation

A retrospective study was conducted in 41 patients with adenocarcinoma of the prostate to investigate the correlation between pathological stage, Gleason score and neuroendocrine differentiation in order to evaluate the prognostic significance of neuroendocrine differentiation. Patients' ages ranged from 50 to 84 (mean 69.1) years. Clinical staging was done by rectal examination, serum PSA, transrectal ultrasonography, bone scan and abdominal CT followed by pathological staging after the operation. After that malignant prostatic tissue sections obtained from radical prostatectomy and transurethral prostatectomy specimens were stained with haemotoxylin-eosin and Gleason scores were determined. From each patient paraffin blocks representative of the primary prostate adenocarcinoma were chosen for immunohistochemical staining with monoclonal neuron specific enolase and chromogranin A antibodies for the determination of neuroendocrine differentiation. Neuroendocrine cells were found to be present in 53.66% of the patients. The incidence of neuroendocrine differentiation was higher in poorly differentiated (Gleason 7-10) tumours when compared to moderately and well differentiated tumours (Gleason <7) although not statistically significant (p=0.09). Although the percentage of neuroendocrine differentiation was greater in advanced prostate carcinoma (stage C, D) than localized (stage A, B) the difference was not statistically significant (p=0.18). Nevertheless, a significant correlation was present between Gleason score and pathological stage (p=0.002). In 34 cases followed for 5 years there was no relationship between the presence of neuroendocrine cells and 5-year tumour progression (p=0.41). However, significant increase in tumour progression rate was observed with increase in Gleason score (p=0.02) and pathological stage (p=0.00001). As a conclusion, no significant correlation was found between neuroendocrine differentiation and prognostic markers such as Gleason score and pathological stage in adenocarcinoma of the prostate.

Pre- and postnatal testosterone administration induces proliferative epithelial lesions with neuroendocrine differentiation in the dorsal lobe of the rat prostate

BACKGROUND

Androgens are implicated in the pathogenesis of prostatic carcinoma. We have elucidated the role of pre- and postnatal testosterone administration in the occurrence of proliferative lesions as well as neuroendocrine (NE) cells in the rat prostatic complex.

METHODS

Female rats were given a single dose of 9 mg testosterone enantate i.m. on day 15 of pregnancy; it gave a high testosterone exposure to the fetus in the early organogenetic period of the rat prostatic complex. One group of the male offspring was followed without further testosterone treatment; a second group received testosterone only in the pubertal period; a third group was given testosterone from puberty and throughout life (46 weeks). These groups were compared to parallel groups (1A-1C) of male offspring without a testosterone supplement in pregnancy.

RESULTS

The serum testosterone concentrations in the rats receiving testosterone were significantly higher than those of control rats. Histopathologically, the testosterone-induced proliferative lesions, mainly hyperplastic, were almost exclusively located in the dorsal lobe. Chromogranin A-immunoreactive (CgA-IR) cells were rarely found normally, but occurred more often in the proliferative lesions (P < 0.001).

CONCLUSIONS

The incidence of proliferative lesions in rats exposed to testosterone only in puberty was comparable to the incidence found in those rats receiving testosterone in puberty and throughout life. This finding may have clinical implications for young athletes, who use testosterone as an anabolic drug. The occurrence of CgA-IR cells increased in proliferative lesions in the dorsal lobe of the rat prostatic complex.

Granin-A, parathyroid hormone-related protein, and calcitonin gene products in neuroendocrine prostate cancer

BACKGROUND

The importance of the expression of granin A (GRN-A, chromogranin-A), calcitonin (CT) gene products (CGPs), and parathyroid hormone-related protein (PTHrP) has become appreciated in the neuroendocrine (NE) differentiation of prostate cancer. We have studied the prostate expression of these three NE cell products with in vivo and in vitro methods.

METHODS

GRN-A secretion was measured by immunoassay in serum samples from patients with prostate cancer. Immunohistology procedures were used to assess GRN-A, CGPs, and PTHrP expression in paraffin-embedded prostate tissue samples. Serum and tumor findings were evaluated according to the patient's clinical status. All three substances were also studied in prostate cancer cell cultures.

RESULTS

GRN-A, PTHrP, and CGPs were all secreted products of prostate cancer. Our studies demonstrated that GRN-A can serve as a prostate cancer serum and tumor marker with clinical value for both diagnosis and prognosis. Elevated serum GRN-A levels identified patients with prostate cancer, including some who did not have elevated serum prostate-specific antigen (PSA) levels. Serum GRN-A concentrations also had prognostic value for prostate cancer. PTHrP and CGPs were expressed in prostate cancer in addition to GRN-A, and all three were secreted by prostate cells in culture. Each had effects on prostate cell growth.

CONCLUSIONS

GRN-A, PTHrP, and CGPs are produced and secreted by prostate cells. These three NE cell products can serve as tumor and markers for prostate cancer that have diagnostic and prognostic value. In addition, their derived peptides regulate prostate cell growth. However, studies more conclusive than the preliminary observations of our group and of other investigators are needed to define the roles of PTHrP, GRN-A, and CGPs in prostate cancer.

Chromogranin A: its clinical value as marker of neuroendocrine tumours

Chromogranin A (CgA) belongs to a family of secretory proteins that are present in densecore vesicles of neuroendocrine cells. Owing to its widespread distribution in neuroendocrine tissues, it can be used as an excellent immunohistochemical marker of neoplasms of neuroendocrine origin. It can also serve as serum marker of neuroendocrine activity because it is co-released with the peptide hormone content of the secretory granules. The serum concentration of CgA is elevated in patients with various neuroendocrine tumours. Elevated levels are strongly correlated with tumour volume. Although its sensitivity and specificity cannot compete with that of the specific hormonal secretion products of most of these tumours, it can nevertheless have useful clinical applications. Neuroendocrine tumours for which no peptide marker is available usually retain the capacity to secrete CgA. CgA can thus be used as serum marker for these so-called 'non-functioning' endocrine tumours. Moreover, in patients with carcinoids and phaeochromocytomas, CgA is a more stable and thus more easily manageable marker than plasma levels of respectively serotonin and catecholamines and their urinary metabolites. Its role as an important general neuroendocrine marker may be extended in the future by the development of immunoscintigraphy of membrane-bound CgA, allowing in vivo visualization of neuroendocrine neoplasms.