P. Anthony di Sant’Agnese

Neuroendocrine cells of the prostate and neuroendocrine differentiation in prostatic carcinoma: a review of morphologic aspects

Neuroendocrine cells of the prostate are intraepithelial regulatory cells that secrete serotonin and a variety of peptide hormones. It is hypothesized that these cells regulate both growth and differentiation, as well as exocrine secretory activity through endocrine, paracrine, neurocrine, and lumenocrine mechanisms. Neuroendocrine differentiation in prostatic carcinoma occurs as pure neuroendocrine malignancies, such as small-cell carcinoma and carcinoid/carcinoid-like tumors, as well as focal neuroendocrine differentiation in a more conventional prostatic adenocarcinoma. Neuroendocrine differentiation in prostatic carcinoma may have diagnostic and prognostic significance.

The Prostatic Endocrine-Paracrine (Neuroendocrine) Regulatory System and Neuroendocrine Differentiation in Prostatic Carcinoma: A Review and Future Directions in Basic Research

Endocrine-paracrine (neuroendocrine, amine precursor uptake and decarboxylation [APUD]) cells of the prostato-urethral region are serotonin and peptide containing regulatory cells, which are part of a dispersed neuroendocrine regulatory system also known as the APUD system. These cells most likely regulate growth and differentiation, as well as the secretory functions of the prostate. Prostatic carcinoma exhibits neuroendocrine differentiation in 3 forms: 1) small cell neuroendocrine carcinoma, 2) carcinoid-like tumors and 3) conventional prostatic adenocarcinoma with focal neuroendocrine differentiation. Small cell carcinoma and carcinoid-like tumors are rather rare (1 to 2% of all prostatic malignancies) and generally pursue an aggressive course. Focal neuroendocrine differentiation in adenocarcinoma is extensive in 10% of the cases and may be present in virtually all adenocarcinomas to a minor degree. There are conflicting studies on the prognostic significance of focal neuroendocrine differentiation in prostatic carcinoma, although several suggest a poor prognosis. The finding that serum neuroendocrine markers predict initial insensitivity to or the development of resistance to hormonal suppression therapy, coupled with the recent observation that androgen receptor is not expressed in neoplastic neuroendocrine cells suggests that neuroendocrine differentiation directly results in resistance to hormonal manipulation therapy. Neuroendocrine differentiation in prostatic carcinoma raises the possibility of innovative modes of treatment. Future directions of research should concentrate on the quantitative analysis of serotonin and various peptides in prostatic malignancy, since high levels of constitutive secretion may not be appreciated by immunocytochemistry, as well as analysis of tumors for receptors to neuroendocrine products, which are necessary for these products to have a functional role. Finally, specific subtypes of neoplastic cells with neuroendocrine differentiation based on serotonin and peptide profiles should be analyzed.

The neuroendocrine prostate: characterization and quantitation of calcitonin in the human gland.

Calcitonin was extracted from surgically-derived prostate tissue, and quantified using radioimmunoassay. Normal prostatic specimens contained 15.18 +/- 10.03 ng./gm. wet weight (mean +/- S.D., n = 20), with a range of 1.50 to 39.62 ng./gm. The result for the hyperplastic tissue samples (n = 20) averaged 0.63 +/- 0.39 ng./gm. with a range of 0.22 to 1.49 ng./gm. This difference was statistically significant (p less than .0001). Dilution profiles for the prostatic calcitonin and synthetic monomeric human calcitonin were congruent, suggesting that the two peptides are identical. A comparison of calcitonin levels and the number of immunohistochemically derived neuroendocrine cells in contiguous tissue sections showed an empiric correlation. The mean calcitonin level in normal human prostate tissue was found to exceed values previously reported for numerous other organs, with the exception of the thyroid gland, the principal source of circulating calcitonin. We propose that a subpopulation of neuroendocrine cells within the prostate gland produce calcitonin, as is the case in the gastrointestinal tract, lung, and other organs. Our findings also support the hypothesis that the calcitonin found in seminal fluid originates in the prostate. Putative roles for calcitonin in the genitourinary system are discussed.

Characterization of the cell-specific expression of parathyroid hormone–related protein in normal and neoplastic prostate tissue

OBJECTIVES Parathyroid hormone-related protein (PTHrP) is a primary factor in the pathogenesis of malignancy-associated hypercalcemia. By alternative splicing, the human PTHrP gene can generate three different species of mRNA that encode three initial translational isoforms of 139, 173, and 141 amino acids. We recently reported that PTHrP was present in normal prostatic neuroendocrine cells and was overexpressed in prostate cancer tissue as demonstrated by immunostaining. This study was undertaken to further clarify the complex expression of PTHrP gene in normal prostate tissue and prostate cancer. METHODS PTHrP mRNA in samples prepared from normal prostate tissue, prostate cancer, and three prostate cancer cell lines, PC3, LNCaP, and DU145 was assessed using Northern hybridization. Expressed PTHrP isoforms were deduced from differential reverse transcription-polymerase chain reaction (RT-PCR) assays with exon-specific primers. Further localization of different species of PTHrP mRNA was performed using nonradioactive in situ hybridization with exon-specific probes on consecutive sections of normal and neoplastic prostate tissue. RESULTS Northern hybridization showed that the PTHrP expression level was higher in prostate cancer than in normal prostate tissue. All three PTHrP isoforms could be detected in normal prostate tissues and prostate cancer with differential RT-PCR. Further analysis using in situ hybridization with exon-specific probes revealed that all three PTHrP isoforms were present in prostatic neuroendocrine cells and only PTHrP-1-139 isoform could be clearly detected in prostate cancer tissue. Two androgen-insensitive cell lines, PC3 and DU145, derived from a bone metastasis and a brain metastasis, respectively, expressed all three mRNA species encoding for the three isoforms, but DU145 cells expressed less than PC3 cells. Androgen-sensitive LNCaP cells exhibited a low level of expression of mRNA species encoding for PTHrP-1-139 and PTHrP-1-173, and no expression of PTHrP1-141 isoform. CONCLUSIONS All three initial translational isoforms of PTHrP are produced by prostatic neuroendocrine cells. The mature products of PTHrP might exert their effects on other prostatic epithelial cells in a paracrine fashion and also participate in the homeostatic regulation of the ejaculate. In prostate cancer, differential expression of these three isoforms is evident and PTHrP-1-139 isoform is more abundant than the other two forms. These findings are valuable for designing future research studies to further elucidate the biological functions of PTHrP in normal prostatic glands and prostate cancer.

Human Papillomavirus Type 6 in Grade I Transitional Cell Carcinoma of the Urethra

Of 4 patients who underwent cystourethroscopy, biopsy and laser excision of suspected urethral condylomata acuminata 3 had coexistent grade I papillary transitional cell carcinoma of the urethra. Human papillomavirus type 6 messenger ribonucleic acid was demonstrated within biopsy specimens using tritium-labeled single-stranded antisense ribonucleic acid probes. Compared to condylomata the papillary transitional epithelium expressed less viral message, which might be expected in an epithelium that does not show full squamous epithelial or koilocytotic differentiation. Among these patients there was 1 papillary transitional lesion in the bladder that, although histologically similar, did not express human papillomavirus message, suggesting differential susceptibility of epithelium between the bladder and urethra. The finding of active human papillomavirus transcription within the urethral papillary transitional lesions raises the possibility of an active role for the virus in the pathogenesis of these lesions. These findings broaden the spectrum of epithelial types reported to support human papillomaviruses and provides impetus for a wider search for these viruses in other transitional cell neoplasms.

Overexpression of Decoy Receptor 3 in Precancerous Lesions and Adenocarcinoma of the Esophagus

Overexpression of decoy receptor (DcR) 3 protein, a recently discovered member of the tumor necrosis factor receptor superfamily, was examined in 40 esophagogastrectomy specimens containing areas of Barrett esophagus (n = 27), low-grade dysplasia (n = 27), high-grade dysplasia or carcinoma in situ (n = 22), and esophageal adenocarcinoma (EAC; n = 28) with immunohistochemical analysis. The results revealed significantly more overexpression of DcR3 in high-grade dysplasia or carcinoma in situ and EAC than in benign esophageal mucosa (both P < .0001), Barrett esophagus (both P < .001), and low-grade dysplasia (P < .01 and P = .033, respectively). Low-grade dysplasia also showed significant overexpression of DcR3 compared with benign esophagus (P < .05) but not with Barrett esophagus (P > .05). DcR3 overexpression seems to negatively correlate with the grade of EAC. Our results suggest that overexpression of DcR3 protein might aid in the diagnosis of high-grade dysplasia or carcinoma in situ and EAC and also might serve as a potential therapeutic target.

Endocrine-Paracrine (APUD) Cells of the Human Female Urethra and Paraurethral Ducts

The distribution, immunostaining profile and ultrastructural morphology of human female urethral and paraurethral endocrine-paracrine (APUD) cells was studied. Five urethras obtained from radical cystectomy specimens were stained with antisera to serotonin, neuron-specific enolase, chromogranin, bombesin, calcitonin, somatostatin, prostatic acid phosphatase, prostatic specific antigen and with the Churukian-Schenk argyrophil method. Numerous endocrine-paracrine cells were observed along the entire length of resected urethra, with these cells most numerous in the paraurethral ducts. The endocrine-paracrine cells were positive for serotonin, neuron-specific enolase, chromogranin and the argyrophil reaction. Scattered bombesin and very rare calcitonin immunoreactive cells were noted. The endocrine-paracrine cells were of the open (luminal extensions) and closed cell types and often had multiple long dendritic processes suggesting a primarily paracrine function. By electron microscopy the secretory granule morphology was highly variable. Autonomic innervation of endocrine-paracrine cells was noted. The relationship of female urethral and paraurethral endocrine-paracrine cells to those of the male prostate and urethra is discussed with speculation as to the functional role these cells may play.

Long Term Human Placental Lobule Perfusion — An Ultrastructural Study

The importance of the ultrastructural evaluation of perfused placental tissue was first emphasized by Panigel (1965, 1971). Ultrastructural study of perfused tissue is now generally accepted as mandatory. Several recent publications have addressed the issue of placental ultrastructural changes after in vitro dual perfusion (Contractor et al., 1984; Illsley et al., 1985; Kaufmann, 1985). These studies involved placental tissue evaluated after only 2–4 hr of perfusion. In this paper we present high resolution light microscopic and electron microscopic findings of placental lobules dually perfused for up to 12 hr. There was excellent overall preservation of morphology. Biochemical and physiological evaluations were also performed demonstrating viability throughout the perfusion period.

Expression of blood group precursor T antigen as a prognostic marker for human bladder cancer treated by bacillus Calmette-Guerin and interleukin-2

The relationship between T antigen expression in transitional cell carcinoma of the bladder and response to bacillus Calmette-Guerin plus interleukin-2 treatment was studied. A total of 25 patients received combined treatment with bacillus Calmette-Guerin and interleukin-2 at weekly instillations for 6 consecutive weeks and then monthly for 1 year. T antigen expression in all patients was studied before treatment. Of the patients 16 had positive T antigen expression in the tumors: 13 (81%) remained free of tumor for an average of 28 months, 3 had a noninvasive recurrence each at 8 to 27 months (mean 18 months) and all responded well to a repeated treatment cycle. Nine patients were negative for T antigen: 1 (11%) remained free of tumor for 11 months, while 8 had recurrence within 12 months. Of the latter 8 patients 2 had noninvasive recurrence each at 4 to 5 months but they responded to a repeated treatment cycle and remained free of tumor for 4 to 22 months (mean 13 months), 4 had subsequent repeated recurrences at 12 to 41 months (mean 22 months) and 2 had progression to deep invasion resulting in cystectomy at 11 to 12 months. Thus, the disease-free rate (continuous complete response) in patients with tumors positive for T antigen was 81%, while that in patients with tumors negative for T antigen was 11% (p less than 0.005, chi-square test). The over-all response rate in patients with positive and negative tumors to bacillus Calmette-Guerin and interleukin-2 treatment was 100 and 33%, respectively, and that for the total patients was 76%. T antigen may serve as a target recognition structure for effector cells generated by bacillus Calmette-Guerin plus interleukin-2 treatment. This study suggests that T antigen is useful to predict the response of bladder tumors to treatment with bacillus Calmette-Guerin and interleukin-2.

Overexpression of Human Carcinoma–Associated Antigen in Esophageal Adenocarcinoma and Its Precursor Lesions

The expression of human carcinoma-associated antigen (HCA), a mucin-type glycoprotein, was assessed in 50 esophagogastrectomy specimens. Areas, each from different cases, of Barrett esophagus (n = 36), low-grade dysplasia (n = 38), high-grade dysplasia/carcinoma in situ (n = 26), and esophageal adenocarcinoma (EAC; n = 34) were examined by immunohistochemical stains to 2 anti-HCA monoclonal antibodies, G1 and HAE3. These two antibodies showed similar staining patterns. HCA was overexpressed significantly in EAC and high-grade dysplasia/carcinoma in situ compared with benign esophageal mucosa (P < .001 for both), Barrett esophagus (P < .001 for both), and low-grade dysplasia (P < .025 for both). HCA overexpression did not correlate with the grade of EAC (P > .1). The results suggest that overexpression of HCA might help in diagnosing esophageal dysplasia and cancer. The correlation of HCA with the grade of esophageal dysplasia suggests its possible involvement in the pathogenesis of EAC. HCA also might provide a target for immunotherapy.