The major 40-kDa glycoprotein in human prostatic fluid is identical to Zn-alpha 2-glycoprotein

MIIP downregulation drives colorectal cancer progression through inducing peri-cancerous adipose tissue browning

BACKGROUND

The enrichment of peri-cancerous adipose tissue is a distinctive feature of colorectal cancer (CRC), accelerating disease progression and worsening prognosis. The communication between tumor cells and adjacent adipocytes plays a crucial role in CRC advancement. However, the precise regulatory mechanisms are largely unknown. This study aims to explore the mechanism of migration and invasion inhibitory protein (MIIP) downregulation in the remodeling of tumor cell-adipocyte communication and its role in promoting CRC.

RESULTS

MIIP expression was found to be decreased in CRC tissues and closely associated with adjacent adipocyte browning. In an in vitro co-culture model, adipocytes treated with MIIP-downregulated tumor supernatant exhibited aggravated browning and lipolysis. This finding was further confirmed in subcutaneously allografted mice co-injected with adipocytes and MIIP-downregulated murine CRC cells. Mechanistically, MIIP interacted with the critical lipid mobilization factor AZGP1 and regulated AZGP1's glycosylation status by interfering with its association with STT3A. MIIP downregulation promoted N-glycosylation and over-secretion of AZGP1 in tumor cells. Subsequently, AZGP1 induced adipocyte browning and lipolysis through the cAMP-PKA pathway, releasing free fatty acids (FFAs) into the microenvironment. These FFAs served as the primary energy source, promoting CRC cell proliferation, invasion, and apoptosis resistance, accompanied by metabolic reprogramming. In a tumor-bearing mouse model, inhibition of β-adrenergic receptor or FFA uptake, combined with oxaliplatin, significantly improved therapeutic efficacy in CRC with abnormal MIIP expression.

CONCLUSIONS

Our data demonstrate that MIIP plays a regulatory role in the communication between CRC and neighboring adipose tissue by regulating AZGP1 N-glycosylation and secretion. MIIP reduction leads to AZGP1 oversecretion, resulting in adipose browning-induced CRC rapid progression and poor prognosis. Inhibition of β-adrenergic receptor or FFA uptake, combined with oxaliplatin, may represent a promising therapeutic strategy for CRC with aberrant MIIP expression.

The potential use of urinary transferrin, urinary adiponectin, urinary Retinol Binding Protein, and serum zinc alpha 2 glycoprotein levels as novel biomarkers for early diagnosis of diabetic nephropathy: A case-control study

BACKGROUND AND AIMS

The level of albuminuria is used to evaluate diabetic nephropathy (DN). However, to detect or predict the early stages of DN, better biomarkers are needed.

METHODS

This study is a case-control observational study. 80 Egyptians participated in the study: 60 patients with type 2 diabetes mellitus (T2DM) were divided into three groups (20 patients each), and 20 healthy subjects with matched age and gender were used as controls. Demographic and laboratory data were analyzed. An enzyme-linked immunosorbent assay was used to determine the levels of four biomarkers of DN; urinary adiponectin (ADP), urinary transferrin, serum Zinc Alpha 2 Glycoprotein (ZAG), and urinary Retinol Binding Protein (RBP).

RESULTS

The levels of DN biomarkers urinary ADP, transferrin, RBP, and serum, ZAG were significantly higher in patients with T2DM than in controls. The ROC curve of the validity of the simultaneous use of all four biomarkers in predicting albuminuria indicates a sensitivity of 90% and a specificity of 90%. The Area Under the Curve (AUC) was 0.948, the 95% confidence interval was 0.998-0.897, and the p-value was 0.001.

CONCLUSIONS

In patients with T2DM, urine adiponectin, transferrin, RBP, and serum ZAG concentration may be useful biomarkers in the early diagnosis of DN. A further longitudinal prospective study is required to explore the potential utility of these biomarkers.

Zinc-α2-glycoprotein as an inhibitor of amine oxidase copper-containing 3

Zinc-α2-glycoprotein (ZAG) is a major plasma protein whose levels increase in chronic energy-demanding diseases and thus serves as an important clinical biomarker in the diagnosis and prognosis of the development of cachexia. Current knowledge suggests that ZAG mediates progressive weight loss through β-adrenergic signalling in adipocytes, resulting in the activation of lipolysis and fat mobilization. Here, through cross-linking experiments, amine oxidase copper-containing 3 (AOC3) is identified as a novel ZAG binding partner. AOC3-also known as vascular adhesion protein 1 (VAP-1) and semicarbazide sensitive amine oxidase (SSAO)-deaminates primary amines, thereby generating the corresponding aldehyde, H2O2 and NH3. It is an ectoenzyme largely expressed by adipocytes and induced in endothelial cells during inflammation. Extravasation of immune cells depends on amine oxidase activity and AOC3-derived H2O2 has an insulinogenic effect. The observations described here suggest that ZAG acts as an allosteric inhibitor of AOC3 and interferes with the associated pro-inflammatory and anti-lipolytic functions. Thus, inhibition of the deamination of lipolytic hormone octopamine by AOC3 represents a novel mechanism by which ZAG might stimulate lipolysis. Furthermore, experiments involving overexpression of recombinant ZAG reveal that its glycosylation is co-regulated by oxygen availability and that the pattern of glycosylation affects its inhibitory potential. The newly identified protein interaction between AOC3 and ZAG highlights a previously unknown functional relationship, which may be relevant to inflammation, energy metabolism and the development of cachexia.

Zinc-α-2-glycoprotein: a candidate biomarker for colon cancer diagnosis in Chinese population

Zinc-α-2-glycoprotein (AZGP1) is a 41-kDa secreted glycoprotein, which has been detected in several malignancies. The diagnostic value of AZGP1 in serum of prostate and breast cancer patients has been reported. Analyzing “The Cancer Genome Atlas” data, we found that in colon cancer AZGP1 gene expression was upregulated at transcriptional level. We hypothesized that AZGP1 could be used as a diagnostic marker of colon cancer. First, we confirmed AZGP1 expression was higher in a set of 28 tumor tissues than in normal colonic mucosa tissues by real-time quantitative PCR and western blot in a Chinese population. We verified that serum concentration of AZGP1 was higher in 120 colon cancer patients compared with 40 healthy controls by ELISA (p < 0.001). Then receiver-operating characteristic (ROC) curve analysis was used to evaluate the predictive diagnostic value of AZGP1 in serum. The area under the curve (AUC) of AZGP1 was 0.742 (p < 0.001, 95% confidence interval (CI) = 0.656–0.827) in between the AUC of carcinoembryonic antigen (CEA) and the AUC of CA19-9, suggesting that predictive diagnostic value of AZGP1 is between CEA and Carbohydrate 19-9 (CA19-9). The combination of AZGP1 with traditional serum biomarkers, CEA and CA19-9, could result in better diagnostic results. To further validate the diagnostic value of AZGP1, a tissue microarray containing 190 samples of primary colon cancer tissue paired with normal colonic tissue was analysed and the result showed that AZGP1 was significantly upregulated in 68.4% (130 of 190) of the primary cancer lesions. In contrast, there was a weakly positive staining in 29.5% (56 of 190) of the normal colonic tissue samples (p < 0.001). Leave-one-out cross-validation was performed on the serum data, and showed that the diagnostic value of AZGP1 had 63.3% sensitivity and 65.0% specificity. Combination of AZGP1, CEA and CA19-9 had improved diagnosis value accuracy with 74.2% sensitivity and 72.5% specificity. These results suggest that AZGP1 is a useful diagnostic biomarker in tissues and serum from a Chinese population.

Decreased expression of AZGP1 is associated with poor prognosis in primary gastric cancer

Background

2-Zinc-glycoprotein 1 (AZGP1) is a multidisciplinary protein that participates in many important functions in the human body, including fertilization, immunoregulation and lipid mobilization. Recently, it has been shown that AZGP1 is also involved in carcinogenesis and tumor differentiation. In this study, we investigated the expression levels and prognostic value of AZGP1 in primary gastric cancers.

Methods and Results

We examined the expression of AZGP1 in 35 paired cancerous and matched adjacent noncancerous gastric mucosa tissues by real-time quantitative RT-PCR (qRT-PCR) and western blotting. Furthermore, we analyzed AZGP1 expression in 248 patients who underwent resection procedures between 2005 and 2007 using immunohistochemistry. The relationships between the AZGP1 expression levels, the clinicopathological factors, and patient survival were investigated. AZGP1 expression was significantly reduced at both the mRNA (P = 0.023) and protein levels (P = 0.019) in tumor tissue samples, compared with expression in matched adjacent non-tumor tissue samples. The immunohistochemical staining data showed that AZGP1 expression was significantly decreased in 52.8% (131/248) of gastric adenocarcinoma cases. Clinicopathological analysis showed that the reduced expression of AZGP1 was significantly correlated with tumor location (P = 0.011), histological grade (P = 0.005) and T stage (P = 0.008). Kaplan–Meier survival curves revealed that the reduced expression of AZGP1 was associated with a poor prognosis in gastric adenocarcinoma patients (P = 0.009). Multivariate Cox analysis identified AZGP1 expression was an independent prognostic factor for overall survival of gastric adenocarcinoma patients (HR = 1.681, 95% CI = 1.134–2.494, P = 0.011).

Conclusions

Our study suggests that AZGP1 might serve as a candidate tumor suppressor and a potential prognostic biomarker in gastric carcinogenesis.

Purification and characterization of a native zinc-binding high molecular weight multiprotein complex from human seminal plasma

The seminal plasma comprises secretions from various accessory sex glands. During fertilization spermatozoa undergo complex sequences of precisely timed events that are regulated by the activation of different intracellular signaling pathways. The precision and efficacy of these pathways are often influenced by the assembly and interactions of multiprotein complexes, thereby directing the flow of regulatory information. Our knowledge about these protein complexes present in human seminal plasma (HuSP) is limited. Here we report the identification and characterization of a native high molecular weight zinc-binding multiprotein complex from HuSP by utilizing 2-DE followed by MS. Twenty-six proteins representing isoforms and/or fragments of 11 different proteins were found to be assembled in this complex. Prostate-specific antigen, zinc α2-glycoprotein, prostatic acid phosphatase, and prolactin inducible protein were the major proteins of this complex. Dynamic light scattering experiments revealed changes in aggregation pattern accompanied with deviation from physiological pH and in presence of SDS. However, no significant changes were observed in the presence of physiological ligands such as zinc and fructose. The present study will be useful and contribute to guide the future studies performed for elucidation of biological significance of this native complex in HuSP.

AZGP1 is a tumor suppressor in pancreatic cancer inducing mesenchymal-to-epithelial transdifferentiation by inhibiting TGF-β-mediated ERK signaling

Epithelial-to-mesenchymal transdifferentiation (EMT) mediated by transforming growth factor-β (TGF-β) signaling leads to aggressive cancer progression. In this study, we identified zinc-α2-glycoprotein (AZGP1, ZAG) as a tumor suppressor in pancreatic ductal adenocarcinoma whose expression is lost due to histone deacetylation. In vitro, ZAG silencing strikingly increased invasiveness of pancreatic cancer cells accompanied by the induction of a mesenchymal phenotype. Expression analysis of a set of EMT markers showed an increase in the expression of mesenchymal markers (vimentin (VIM) and integrin-α5) and a concomitant reduction in the expression of epithelial markers (cadherin 1 (CDH1), desmoplakin and keratin-19). Blockade of endogenous TGF-β signaling inhibited these morphological changes and the downregulation of CDH1, as elicited by ZAG silencing. In a ZAG-negative cell line, human recombinant ZAG (rZAG) specifically inhibited exogenous TGF-β-mediated tumor cell invasion and VIM expression. Furthermore, rZAG blocked TGF-β-mediated ERK2 phosphorylation. PCR array analysis revealed that ZAG-induced epithelial transdifferentiation was accompanied by a series of concerted cellular events including a shift in the energy metabolism and prosurvival signals. Thus, epigenetically regulated ZAG is a novel tumor suppressor essential for maintaining an epithelial phenotype.

Three predominant prostatic proteins

Prostatic acid phosphatase (PAP), prostate-specific antigen (PSA; or gamma-seminoprotein), and beta-microseminoprotein (beta-MSP; PSP94 or beta-inhibin) are the three predominant proteins secreted by the normal human prostate gland. In the epithelium of normal and hyperplastic prostatic acini and ducts PAP, PSA and beta-MSP have an identical immunohistochemical localization. Highly differentiated (grade I) carcinomas contain an almost equal number of PAP-, PSA- and beta-MSP-immunoreactive cells; the incidence of these cells is lower and they display a greater staining variability in the moderately and poorly (grade II-III) differentiated tumours. Especially in poorly differentiated tumours PSA seems to be a more sensitive immunohistochemical marker than PAP or prostatic carcinomas. Moreover, the use of PAP as a marker for prostatic carcinomas is complicated by the reported structural similarities between the prostatic secreted acid phosphatase and lysosomal acid phosphatase occurring in all tissues. The use of beta-MSP as a marker for prostatic carcinomas may be limited by indications of non-prostatic production of this protein.

Zinc alpha 2-glycoprotein: a multidisciplinary protein

Zinc alpha 2-glycoprotein (ZAG) is a protein of interest because of its ability to play many important functions in the human body, including fertilization and lipid mobilization. After the discovery of this molecule, during the last 5 decades, various studies have been documented on its structure and functions, but still, it is considered as a protein with an unknown function. Its expression is regulated by glucocorticoids. Due to its high sequence homology with lipid-mobilizing factor and high expression in cancer cachexia, it is considered as a novel adipokine. On the other hand, structural organization and fold is similar to MHC class I antigen-presenting molecule; hence, ZAG may have a role in the expression of the immune response. The function of ZAG under physiologic and cancerous conditions remains mysterious but is considered as a tumor biomarker for various carcinomas. There are several unrelated functions that are attributed to ZAG, such as RNase activity, regulation of melanin production, hindering tumor proliferation, and transport of nephritic by-products. This article deals with the discussion of the major aspects of ZAG from its gene structure to function and metabolism.

Proteomic approach for purification of seminal plasma proteins involved in tumor proliferation

Human seminal plasma contains a large array of proteins required for the normal physiology and metabolism of spermatozoa. These are mainly secreted from prostate epithelium, testes, and seminal vesicles. Fortunately, many of these are found to be present at elevated concentration in seminal plasma and act as a biomarker of different carcinomas as their levels are also enhanced in serum and are found to be involved in tumor progression and metastasis apart from fertility. The proteins which were overexpressed in the seminal plasma of prostate carcinoma patients were identified by 2-DE and MALDI-TOF/MS. We have designed a strategy to purify these four proteins prostate specific antigen (PSA), prostatic acid phosphatase (PAP), Zinc alpha2-glycoprotein (ZAG), and progastricsin (PG), together in homogeneity by using simple chromatographic techniques. Acidic and basic fractions of human seminal plasma were separated by ion exchange chromatography and further purified by gel permeation chromatography. Our results form a new and valuable resource for those attempting structure-based drug designing for prostate and other cancers where the amount of proteins is required in plenty and in native form.

Zinc-alpha2-glycoprotein expression as a marker of differentiation in human oral tumors

Zinc-alpha2-glycoprotein (Znalpha2gp) is a soluble major histocompatibility complex homolog widespread in body fluids and in glandular epithelia; the authors recently demonstrated its presence in stratified epithelia. Znalpha2gp has been associated with tumor differentiation in breast cancers and other carcinomas. We compare here its gene expression in histopathologically graded oral squamous cell carcinomas and in their perilesional normals. Znalpha2gp levels are higher in the controls than in the tumors, and higher in well-differentiated tumors than in poorly differentiated ones. Markers of oral epithelial maturation (keratin K13 and involucrin) are less simply related to tumor histology.

The expression of beta-microseminoprotein gene is regulated by cAMP

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.

Zinc-alpha 2-glycoprotein has ribonuclease activity

Zinc-alpha 2-glycoprotein (Zn alpha 2gp) is widely distributed in body fluids and in various epithelia; its gene has been completely sequenced, but its function has long remained elusive. We have found that Zn alpha 2gp has RNase activity, comparable to onconase but two orders of magnitude less than RNase A. The RNase activity of Zn alpha 2gp is characterized by maxima in pH at 7.5, in ionic strength at 50 mM NaCl, and in temperature at 60 degreesC. It is strongly inhibited by ZnCl2, but unaffected by MgCl2. It is partially inactivated (down to 20%) by the placental RNase inhibitor. On synthetic polyribonucleotide substrates, the RNase activity of Zn alpha 2gp is specific for pyrimidine residues [poly(C) and poly(U) equally] and cleaves only single-stranded RNA. For onconase, it has been demonstrated that the RNase activity depends on pyroglutamic acid (pyr 1) as the N-terminus; Zn alpha 2gp also has pyr 1, while RNase A does not. Alignment of the amino acid sequences of Zn alpha 2gp and onconase or RNase A reveals only modest matches. Despite the more substantial overall structural homology of Zn alpha 2gp to class I major histocompatibility complex proteins, Zn alpha 2gp has not been proven to be associated with the immune response and, conversely, we could not detect RNase activity in six class I HLA heavy chains.

Prostatic kallikrein hK2, but not prostate-specific antigen (hK3), activates single-chain urokinase-type plasminogen activator

Our work was undertaken to compare the relative efficiency of 2 purified prostatic kallikreins, namely, hK2 and prostate-specific antigen (PSA or hK3), in the activation of single-chain urokinase (scuPA). We found that hK2 converts scuPA into an active enzyme with an efficiency equal to approximately 1/50 that of plasmin. During the activation of scuPA by hK2, two fragments of 33 and 22 kDa were generated. The NH2-terminal amino acid sequence of the 33 kDa fragment showed that hK2 cleaved scuPA between Lys158 and Ile159. In contrast to a previous report by another group, our purified hK3 preparation containing no trypsin-like contaminants was totally unable to activate scuPA. Our results show that kallikrein hK2 has plasmin-like activity and suggest that it could be the initiator of a proteolytic cascade leading to prostatic cancer invasion.

Cloning and expression analysis of the cDNA encoding rat Zn-alpha 2-glycoprotein

We report here the nucleotide (nt) sequence of a rat liver cDNA encoding Zn-alpha 2-glycoprotein (Zn-alpha 2-gp), a plasma protein with a high degree of sequence similarity to class-I major histocompatibility complex (MHC) antigens. The deduced amino acid (aa) sequence contains the coding information for 293 aa residues and shows 60% identity with the aa sequence of human Zn-alpha 2-gp and 35% identity with that corresponding to the extracellular domains of RT1, a rat class-I MHC antigen. Northern blot analysis showed that rat Zn-alpha 2-gp is expressed in liver, but not in a wide number of tissues, including prostate, mammary gland, kidney, intestine, lung, pancreas, ovary, uterus, thyroid, placenta, spleen, brain and heart.

Glucocorticoids and androgens up-regulate the Zn-alpha 2-glycoprotein messenger RNA in human breast cancer cells

We have studied the hormonal regulation of the gene encoding Zn-alpha 2-glycoprotein (Zn-alpha 2-gp), a human protein with a high degree of amino acid sequence similarity to class I histocompatibility antigens that is produced by a specific subset of breast carcinomas. Northern blot analysis revealed that dexamethasone and 5 alpha-dihydrotestosterone strongly induced the accumulation of Zn-alpha 2-gp mRNA in T-47D human breast cancer cells. Furthermore, the effect of these two hormones was shown to be additive, since the combination of both hormones produced a stimulation of Zn-alpha 2-gp mRNA of at least 3-fold over that produced by either hormone alone. By contrast, the addition of 5 beta-dihydrotestosterone, 17 beta-estradiol, or progesterone failed to induce the expression of Zn-alpha 2-gp. The stimulatory effect of glucocorticoids and androgens on Zn-alpha 2-gp expression was produced in a time and dose dependent manner, without significantly affecting the cell proliferation rate. A time-course study demonstrated that the induction of Zn-alpha 2-gp mRNA by androgens and glucocorticoids reached a level of 4 or 3.2-fold over the untreated control after seven days of incubation in the presence of a 10(-7) M concentration of 5 alpha-dihydrotestosterone or dexamethasone, respectively. A dose-response study showed that as little as 10(-11) M of 5 alpha-dihydrotestosterone or dexamethasone produced an accumulation of Zn-alpha 2-gp mRNA of 2.4 or 2.1-fold over the control, respectively. On the basis of these results, we propose that Zn-alpha2-gp may be useful as a biochemical marker of breast carcinomas with a specific pattern of hormone responsiveness in whose development glucocorticoids and/or androgens may play a significant role.

Human Zn-alpha 2-glycoprotein: complete genomic sequence, identification of a related pseudogene and relationship to class I major histocompatibility complex genes

The human gene (AZGP1) encoding Zn-alpha 2-glycoprotein (Zn-alpha 2-gp), a protein present in several biological fluids and produced by a subtype of breast carcinomas, has been cloned and its complete nucleotide sequence determined. The gene spans over 9.7 kb, and its overall organization and nucleotide sequence are very similar to those of the first four exons of class I MHC genes. However, the Zn-alpha 2-gp gene differs from these genes in several significant ways. It lacks the coding information for the transmembrane and cytoplasmic domains typical of MHC genes, which is consistent with its presence as a soluble protein in different physiological and pathological fluids. In addition, it contains a high density of repetitive sequences, including Alu, MER, and MIR elements, which are not present at equivalent positions in class I MHC genes. Finally, its 5'-flanking region lacks the class I MHC regulatory complex and the interferon consensus sequence characteristic of class I MHC genes. These findings may explain the different expression pattern of Zn-alpha 2-gp and class I MHC genes in human tissues. Southern blot hybridization of DNA from several species with a cDNA probe indicated that Zn-alpha 2-gp genes are present in a wide variety of animal species, including monkey, rat, mouse, dog, cow, and rabbit. The human genome also contains a putative Zn-alpha 2-gp pseudogene that has been isolated and partially characterized. This pseudogene has an intron-exon organization identical to that of the functional gene, but it presents two deleterious mutations in the third exon that lead to the appearance of premature stop codons. Finally, considering the lack of polymorphism in the Zn-alpha 2-gp gene in comparison with MHC genes, putative roles for this human glycoprotein in the transport of nonpolymorphic substances or in intercellular recognition processes are proposed.

Cloning and nucleotide sequence of a human Zn-alpha 2-glycoprotein cDNA and chromosomal assignment of its gene

A cDNA clone of Zn-alpha 2-glycoprotein (Zn alpha 2gp) was isolated from a human prostate library. The amino acid sequence of prostate Zn alpha 2gp deduced from the nucleotide sequence was identical to the one previously reported on the Zn alpha 2gp protein purified from human blood plasma, except at three positions: the 65th and 222nd amino acid residues were Gln (----Glu) and Glu (----Gln), and there was a two amino acid insertion (Ile-Phe) between the 75th (Glu) and 76th (Met) amino acids. Southern blot analysis of human genomic DNA, however, suggested a single gene encoding Zn alpha 2gp. Using a panel of rodent-human somatic cell hybrids, the Zn alpha 2 gp gene was assigned to human chromosome 7.

Glycoconjugates of the lateral prostate of the guinea pig: a lectin histochemical study

The present study examined the glycoconjugates of the lateral prostate using a battery of lectins. The results indicated that the secretory epithelium was rich in mannose (Man), N-acetylglucosamine (GlcNAc), galactose (Gal), N-acetylgalactosamine (GalNAc), and complex oligosaccharides. Con A (concanavalin A), LCA (Lens culinaris agglutinin), PSA (Pisum sativum agglutinin), WGA (wheat germ agglutinin), PWM (pokeweed mitogen), RCA-I (Racinus communis isolectin I), and PHA-P (Phaseolus vulgaris agglutinin-P) reacted intensely with both epithelia and stroma, while SBA (soybean agglutinin) and PNA (peanut agglutinin), which bind to terminal Gal, GalNAc, and Gal beta 1,3 GalNAc appeared to be specific to the secretory epithelium. SBA and PNA were useful as markers in the study of the secretory function of the prostate gland. The present study has shown that the Golgi apparatus of prostatic epithelial cells was rich in fucose (Fuc), oligomers of GlcNAc, Gal beta 1,3 GalNAc, Gal, and Man containing glycoconjugates, indicating that the gland was actively involved in glycosylation. The present study has also shown that LTA (Lotus tetragonolobus agglutinin) is a good marker for the epithelial Golgi. PNA also bound to the epithelial basement membrane and the connective tissue in the lamina propria. The present study has thus established, for the first time, the glycoconjugate patterns in the lateral prostate of the guinea pig.

Morphologic and regulatory aspects of prostatic function

Current concepts of the structural and functional organization of the human prostate are presented and are related to endocrine principles which have been studied in experimental animals. Based on embryological and histological studies, the internal structure of the human prostate gland is divided into four subdivisions: 1. the anterior nonglandular fibromuscular stroma. 2. the periurethral portion, 3. the peripheral zone, and 4. the central zone. The central zone which accounts for 25% of the gland, is formed by a wedge-shaped group of ducts, arising close to the orifices of the ejaculatory ducts and is surrounded by the peripheral zone (75% of the gland). The functional interdependence and relationship between the stroma and the epithelium observed during embryological development, postnatal maturation and under certain pathological conditions, has led to the concept of a functional prostatic unit, which is useful for the explanation of prostatic growth and the expression of specific genes. There is growing evidence of a functional heterogeneity within the prostatic secretory duct system, with a concentration of estrogen-sensitive cells close to the urethra, and a relatively long persistence of undifferentiated nonsecretory acini at the peripheral tips of the gland ducts close to the dorsal capsule until late puberty. Secretory and proliferative activities of the gland are strictly androgen-dependent. Of particular importance with respect to glandular and stromal proliferation are the recent reports on the presence of different growth factors in the prostate. Hormonally induced imbalances in the system of growth factor production, androgen- and estrogen-dependence and general ageing of the cells have to be taken into consideration in understanding various prostatic pathologies such as benign prostatic hyperplasia and prostate cancer.

Synthesis of alpha 1-acid glycoprotein by the human prostate

In order better to define the extent of protein synthesis capacity of the human prostate, we have studied the translation of selected serum proteins using isolated poly(A)+ RNA preparations and the rabbit reticulocyte lysate system. The translation of alpha 1-acid glycoprotein could be conclusively demonstrated but there was no apparent translation of albumin and plasmatic transferrin. Labeled alpha 1-acid glycoprotein was identified by specific immunoprecipitation with a commercial anti alpha 1-acid glycoprotein antiserum and correct processing by canine pancreatic microsomal membranes. Furthermore, we have shown by the immunoperoxidase technique that alpha 1-acid glycoprotein was indeed localized mainly in prostatic epithelial cells in 2 out of 2 patients with benign prostatic hypertrophy and in 3 out of 11 patients with prostatic adenocarcinoma. The significance of the synthesis and secretion of alpha 1-acid glycoprotein by prostatic cell themselves is presently unknown. However, we think that it could represent an interesting subject to explore further in relation with prostatic inflammation.