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BACKGROUND: Prostatic secretory protein of 94 amino acids (PSP94), probasin, and seminal vesicle secretion II (SVSII) are the three major proteins secreted by the lateral lobe of the rat prostate gland. Among these proteins, rodent PSP94 but not probasin and SVSII has a human homologue and it is also a major secretory protein of the human prostate, in addition to prostatic acid phosphatase and prostate-specific antigen. METHODS: In this study, we examined and compared the mRNA expression of these three secretory markers in three rat models of prostate cancer including the sex steroid-induced dysplasia (prostatic intraepithelial neoplasia or PIN) in Noble (Nb) rat model, an androgen-independent Nb rat prostatic tumor (AIT) and Dunning rat prostatic adenocarcinomas (both androgen-dependent and -independent) by in situ hybridization (ISH), reverse transcriptase-polymerase chain reaction (RT-PCR), and immunohistochemistry. RESULTS: The transcripts for the three markers were highly expressed in the secretory epithelium of normal lateral prostate (LP). Their hybridization signals became reduced in the epithelial cells in the low-grade PINs and significantly weakened or lost in the high-grade PINs induced in the LP. Interestingly, we observed that some dysplastic cells located at the basal compartment of the PIN lesions, and nests of outpouching epithelial cells in the vicinity of PINs, expressed positive hybridization signals of three markers. In the adenocarcinoma, signals of probasin but not PSP94 and SVSII were detected. No hybridization signals were detected in both Dunning and AIT tumors. By RT-PCR, transcripts for these proteins were still detected but significantly reduced in the Dunning tumors, whereas in the AIT tumor, only SVSII transcripts were detected. Immunohistochemistry of PSP94 also showed a reduced staining in the PIN lesions, but no immunoreactivity was seen in the rat prostatic tumors. CONCLUSIONS: The mRNA expression of the three prostatic secretory markers were decreased in the hormone-induced PINs and in two rat prostatic tumors, indicating that the androgen-regulated secretory differentiation was impaired during the development of the premalignant lesion and further reduced in advanced tumors. The abnormal expression pattern of these secretory markers and androgen receptor (AR) in the basal compartment of the PIN lesions suggests that there is a population of cell types with secretory phenotype appearing in the basal cell layer during the early malignant transformation of the prostatic epithelium.
BACKGROUND: Prostate-specific antigen (PSA) is a widely used serum marker for prostate cancer, but has a poor specificity for early detection at levels below 10 ng/ml, because it can also result from benign conditions. Our aim was to determine the frequencies of circulating PSA+ macrophages in a blinded study and to examine the suitability of this new method for differentiating between benign and malignant prostate disease. METHODS: Between October 2002 and February 2003, 126 patients undergoing transrectal biopsy were enrolled in this study. Peripheral blood macrophages were stained for intracellular content of PSA in all patients. Ten patients' peripheral blood mononulear cells (PBMCs) were also supplementarily stained for cytokeratin (CK) and epithelial membrane antigen (EMA). Macrophages were analysed by flow cytometry. Patients were grouped according to their biopsy histology and bone scan results. FINDINGS: Based on histological data, patients were classified as having no evidence of malignancy (NEM) (n = 59), prostatitis (n = 20), or localised prostate cancer (n = 37). Significantly higher levels of circulating PSA+ macrophages were found in prostate cancer compared to benign conditions. Calculating a 2% cut-off level enabled the detection of localised prostate cancer with 89% sensitivity and 80% specificity. In a subset of patients (65%) with a serum PSA below 4 ng/ml and confirmed prostate cancer, the percentage of PSA+ macrophages was significantly higher compared to NEM and prostatitis. Macrophages of ten patients tested with prostate cancer contained significantly higher amounts of PSA, EMA, and CK compared to ten with NEM. INTERPRETATION: Intracellular PSA in combination with CK and EMA can be found in permeabilized blood macrophages, indicating phagocytosis of complete cancer cells. This study further suggests, that this new method might be suitable for differentiating between prostate cancer and benign conditions especially in patients with low serum PSA.
BACKGROUND: Recently identified associations of prostate cancer risk with several genes involved in innate immunity support a role of inflammation in the etiology of prostate cancer. Considering inflammation is regulated by a complex system of gene products, we hypothesize sequence variants in many other genes of this pathway are associated with prostate cancer. METHODS: We evaluated 9,275 SNPs in 1,086 genes of the inflammation pathway using a MegAllele genotyping system among 200 familial cases and 200 unaffected controls selected from a large Swedish case-control population (CAPS). RESULTS: We found that significantly more than the expected numbers of SNPs were significant at a nominal P-value of 0.01, 0.05, and 0.1, providing overall support for our hypothesis. The excess was largest when using a more liberal nominal P-value (0.1); we observed 992 significant SNPs compared with the 854 significant SNPs expected by chance, and this difference was significant based on a permutation test (P = 0.0025). We also began the effort of differentiating true associated SNPs by selecting a small subset of significant SNPs (N = 26) and genotyped these in an independent sample of approximately 1,900 CAPS1 subjects. We were able to confirm 3 of these 26 SNPs. It is expected that many more true associated SNPs will be confirmed among the 992 significant SNPs identified in our pathway screen. CONCLUSIONS: Our study provides the first objective support for an association between prostate cancer and multiple modest-effect genes in inflammatory pathways.
Prostatic acid phosphate (PAP), prostate-specific antigen (PSA), and beta-microseminoprotein (beta-MSP) were regularly localized immunohistochemically to the epithelium of the acini and that of the ducts in the nodules of 24 cases of benign prostatic hyperplasia. The immunohistochemical distribution of these three prostatic-secreted proteins was also examined, with monoclonal antisera against PAP and PSA and with polyclonal antisera against PAP, PSA, and beta-MSP, in a series of 40 cases of prostatic adenocarcinomas graded according to the WHO classification. Highly differentiated (grade I) carcinomas showed a high incidence of PAP-, PSA-, and beta-MSP-immunoreactive cells. As in the normal and hyperplastic prostate parenchyma, highly differentiated (grade I) carcinomas were found to contain an almost equal number of PAP-, PSA-, and beta-MSP-immunoreactive cells. When semiquantitatively assessed, the incidence of PAP-, PSA-, and beta-MSP-immunoreactive cells was found to be lower in the moderately and poorly differentiated (grades II and III) tumors than in the highly differentiated ones; they also showed greater staining variability. Tumor cells immunoreactive with a monoclonal antiserum raised against PAP in carcinomas of grades II and III were less frequent than tumor cells immunoreactive with antisera against PSA, beta-MSP, and a polyclonal antiserum against PAP. The almost identical distribution of PSA and beta-MSP in carcinomas of grades II and III suggests that PSA and beta-MSP are not less sensitive tumor markers than PAP for the monitoring of the course and the treatment of prostatic carcinomas.
An immunohistochemical technique for determination of "estramustine-binding protein" (EMBP) in rat prostate is described. The localization and staining intensity of this protein were correlated to prostatic morphological structures in intact animals and at different time intervals after androgen deprivation by castration. EMBP was found almost exclusively in epithelial cells, while the fibromuscular stroma seemed to be negative. Intracellularly, immunostaining was confined to the cytoplasm, but was absent in nuclei. In intact rats, acinar lumina demonstrated heavy immunostaining, indicating secretion of EMBP. Orchiectomy caused a diminution of EMBP expression as well as secretion, suggesting that EMBP synthesis is under androgenic regulation. Human benign hyperplastic and cancerous prostatic specimens were also examined. All human specimens examined so far exhibited positive epithelial staining although of varying intensity. Therefore, this immunohistochemical technique may be used for studying the correlation of EMBP with tumor malignancy grade and for clinical investigations of how various treatments affect EMBP expression in prostatic carcinomas.
Serum prostate secretory protein (PSP) levels were measured in 49 patients with benign prostatic hyperplasia (BPH), 144 patients with various stages of prostatic carcinoma (CaP), and 82 CaP patients who were followed serially. PSP values were compared with serum levels of prostate specific antigen (PSA) and prostatic acid phosphatase (PAP). In the BPH group, PSP was elevated (> 10 ng/ml) in 41% of patients, whereas PSA (> 4 ng/ml) and PAP (> 3.3 ng/ml) were elevated in 39% and 23% of the cases, respectively. PSP levels were elevated in 48% of the CaP pretreatment specimens, compared to 79% for PSA and 40% for PAP. PSP levels in cancer patients who had intracapsular disease were about two to three times higher than those observed for PAP. PSP was found to be the only marker elevated in eight (6%) pretreatment CaP patient serum specimens, while PAP was never found to be elevated when PSA was normal. PSP serum concentrations correlated with the clinical course of the disease in 79% of patients, compared with 90% for PSA and 66% for PAP. In certain patients, monitored over time, disease correlation was reflected in serum values with only a single biomarker, i.e., 1% with PAP, 8% with PSP, and 10% with PSA. This study has shown that PSP is a less sensitive serum biomarker than PSA, but more sensitive than PAP for detection and monitoring the early stages of prostate cancer. This suggests that PSP as a biomarker may be a useful adjunct for the management of a subpopulation of low-stage and -grade CaP.
Prostatic inhibin peptide (PIP) is a 94-amino acid peptide involved in various cellular functions. The concentration of this peptide changes with prostatic pathophysiology suggesting a role in various disease conditions; present study was undertaken to investigate the presence of this peptide in two human prostatic cell lines: LNCaP and PC3 cells. The LNCaP cells showed an intense intracellular fluorescence pattern after staining with rabbit-anti-PIP antiserum and FITC conjugated goat antirabbit-IgG, while the PC3 cells did not exhibit any fluorescence. There was no alteration in the concentration of PIP in LNCaP cells with or without supplementation of steroids in culture medium. Immunoblot analysis indicates similarities between PIP from LNCaP cells and that from the human seminal plasma. Thus, present study demonstrates the presence of PIP in a human prostatic cell line, i.e., LNCaP cells. Its intracellular concentration is androgen independent, and has a close similarity with PIP isolated from the human seminal plasma.
The expression of estramustine-binding protein (EMBP) was studied immunohistochemically in whole-mount prostate sections. Specimens were taken from the prostates of 15 patients who had undergone total prostatectomy due to localized (TOd-T2 NO MO) prostatic cancer (PC). Almost all the examined whole-mount sections displayed areas with prostatic intraepithelial neoplasia (PIN). PIN is regarded as the main precursor of invasive PC. High- and low-grade PIN expressed EMBP. The average positively stained areas accounted for averages of 69.2% and 48.7%, respectively. High-grade PIN contained the highest EMBP levels of all the investigated (benign and malignant) epithelia, followed by moderately differentiated PC. With regard to areas with PC, the highest levels of EMBP expression (61.3%) were observed in moderately differentiated PC; poorly differentiated PC came second. Of all the examined epithelia, EMBP levels were lowest in well-differentiated PC (25.8%). Normal prostatic epithelia and hyperplasia were characterized by low EMBP expression, although somewhat higher than well-differentiated PC. A moderate expression (45%) was observed in the seminal vesicles. According to these results, EMBP was expressed mainly in the diseased peripheral zone (PZ), where PIN and prostatic cancer have their highest prevalence.
The promoter of the human gene for beta-microseminoprotein (MSP) was analyzed by transient transfection assay using LNCaP cells. The region between -2738 and -207 was not essential for the basal promoter activity, but regions from -206, -108, and -83 were necessary. Forskolin induced promoter activity to 3- to 14-fold when constructions containing the possible cAMP response element (CRE, -60 to -53) were used, but did not do so when it was deleted from them. In a gel-mobility shift assay using a probe corresponding to -68 to -48, the shifted band was competed with a consensus CRE, and supershifted when the anti-CREB-1 antibody was included. Forskolin added to LNCaP cells increased MSP mRNA to 6-fold within 12 h. These results suggest that the expression of MSP gene is regulated by cAMP via the CRE present in the promoter. Hormones such as (-)-epinephrine or vasoactive intestinal polypeptide also increased MSP mRNA to 2- to 3-fold.
CD178 (CD95-ligand) is expressed on several tumor cells and likely influences the interaction of the tumor with the host immune system. However, little is known about the mechanisms that regulate its expression on the cell surface. We have evaluated the ability of various compounds and cytokines to regulate cell surface expression and release of soluble CD178 in various carcinoma cell lines. Vitamin E succinate (VES) and retinoic acid (RA) were found to reduce CD178 surface expression, whereas interferon-gamma stimulated a slight upregulation. At 48 h, the regulation of surface CD178 by VES and RA arose from a small decrease in CD178 mRNA and to a greater extent due to an increase in the release of soluble CD178; the latter was blocked by addition of a metalloproteinase inhibitor. Accordingly, VES and RA treatment diminished the ability of tumor cells to kill CD95-sensitive cells and this effect was markedly reduced by the presence of a metalloproteinase inhibitor. Our results indicate that, in vitro, CD178 expression on the cell surface of tumor cells can be regulated by agents that alter both expression and release of the ligand. In vivo, such treatments may play an important role in the outcome of tumor sensitivity or resistance to host immune mechanisms.
The use of peptide analogs for the therapy of various cancers is reviewed. Inhibition of the pituitary-gonadal axis forms the basis for oncological applications of luteinizing hormone-releasing hormone (LH-RH) agonists and antagonists, but direct effects on tumors may also play a role. Analogs of somatostatin are likewise used for treatment of various tumors. Radiolabeled somatostatin analogs have been successfully applied for the localization of tumors expressing somatostatin receptors. Studies on the role of tumoral LH-RH, growth hormone-releasing hormone (GH-RH), and bombesin/GRP and their receptors in the proliferation of various tumors are summarized, but the complete elucidation of all the mechanisms involved will require much additional work. Human tumors producing hypothalamic hormones are also discussed. Treatment of many cancers remains a major challenge, but new therapeutic modalities are being developed based on antagonists of GH-RH and bombesin, which inhibit growth factors or their receptors. Other approaches consist of the use of cytotoxic analogs of LH-RH, bombesin, and somatostatin, which can be targeted to receptors for these peptides in various cancers and their metastases. These new classes of peptide analogs should lead to a more effective treatment for various cancers.
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