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

Expression of prostate glycoconjugates in the stallion and castrated horse

This work was undertaken to determine the glycoconjugates secreted by the epithelium of the prostate in the intact stallion and castrated horse using lectin histochemical procedures in conjunction with enzymatic digestion and deglycosylation treatments. Additionally, anti-5 and 13-16-cytokeratin antibodies were used to localize epithelial basal cells. In the stallion, lectin histochemistry showed the following sugar residues in the Golgi zone of the glandular cells: α-Glu/Man, α-Fuc and β-Gal included in both O- and N-linked oligosaccharides as well as β-GalNAc, GlcNAc and α-Gal, which belonged to O-glycoproteins. β-Gal and β-GalNAc moieties were also noted subterminal to sialyl residues. Sialic acid specific lectins identified Neu-5Ac(α2,3-6)-β-Gal or Neu5Ac(α2,6)-β-GalNAc sequences in both N- and O-bound glycoproteins. The prostatic glandular cells of the castrated horse expressed some of the same sugar moieties found in the stallions, such as α-Glu/Man, α-Gal and GlcNAc, but significant differences were also noted. In particular, β-D-GalNAc was only detected subterminal to sialic acid, β-D-Gal-(1-3)-D-GalNAc was found in N-linked glycans, whereas β-D-Gal-(1-4)-D-GlcNAc and Neu5Acα2,6Gal/GalNAc were noted only in O-glycoproteins. These results indicate that the lectin binding patterns in glandular cells may be modified by sex hormones. No specific lectin labelling of basal cells was found in either the stallion or the castrated horse even though they were immunostained with specific anti-cytokeratin antibodies. These cells stained more strongly in the castrated horse than in the intact stallion suggesting that they are androgen responsive. The glycomolecules detected in the equine prostate secretions may contribute to the remodelling of the sperm surface, which occurs during sperm transit through the male genital tract and also after ejaculation in the seminal plasma. These changes may be important in the understanding of the stallion fertility.

Lectin binding patterns in hyperplastic and metaplastic bullock prostate tissues after diethylstilbestrol administration

Hyperplasia and squamous metaplasia of the prostatic epithelium are conditions induced by oestrogens. Diethylstilbestrol (DES) has been banned from cattle used for beef production because of the health risks. The potential use of molecular markers for the detection of illegal oestrogen administration was evaluated by taking samples of prostatic tissue from control bullocks, bullocks which had been treated with oestrogens, and bullocks sacrificed 21 and 90 days after a single dose of DES. The expression of the glycoconjugates was examined by lectinhistochemistry and the lectin binding pattern was characterised in epithelium and connective tissue. In the animals sacrificed after 21 days there was an increase in the binding of one lectin (JAC) and there was an increase in the binding of one of the other lectins (DBA) in the animals sacrificed after 90 days. An increase in SWGA lectin staining was observed in the bullocks that had probably been treated with oestrogen and in the animals sacrificed 90 days after the inoculation with DES. There were also differences between the binding of SWGA in the control bullocks and the other groups.

Analysis of glycoconjugate patterns of normal and hormone-induced dysplastic Noble rat prostates, and an androgen-independent Noble rat prostate tumor, by lectin histochemistry and protein blotting

BACKGROUND

Alteration of the expression of glycoconjugates is frequently observed in tumors. However, studies on the changes of cellular glycosylation in the early premalignant stage of prostate carcinogenesis are scarce.

METHODS

The present study characterized and compared the glycoconjugates expressed in the dysplastic lateral prostate induced in Noble (Nb) rat by steroid hormones and a transplantable androgen-independent Nb rat prostatic carcinoma line (AIT) by lectin histochemistry and protein blotting.

RESULTS

The results of lectin histochemistry show that the dysplastic prostatic epithelium elaborates altered patterns of glycosylation, which are distinct from the normal secretory epithelium. Some individual cells in the dysplastic epithelium were intensely labeled by the N-acetylgalactosamine (GalNAc)-specific (agglutins from Glycine max [SBA], Helix aspera [HAA], Helix pomatia [HPA], Vicia villosa [VVA], Erythrina cristigalli [ECA]) and complex-type oligosaccharide-specific (Phaseolus vulgaris agglutin [PHA-E]) lectins, indicating that these cells contained abundant GalNAc(alpha1,3)GalNAc/Gal and Gal(beta1,4)GlcNAc(alpha1,2)Man(alpha1,6) residues. These lectins also bound to some tumor cells in the AIT, suggesting that these sugar residues are common in some dysplastic and neoplastic prostatic cells. The study has also identified several lectins (agglutins from Griffonia simplicifolia [GS-I-B4], Arachis hypogaea [PNA], Ricinus communis [RCA-I], Maackia amurensis [MAA], Sambucus nigra [SNA]), which bound only to some AIT tumor cells but not to dysplastic epithelium, indicating that alpha/betaGal and sialic acid-containing glycoconjugates are expressed by neoplastic prostatic cells. The results of lectin blottings with Triticum vulgare agglutin [S-WGA] Ulex europaeus agglutin [UEA-I] and PHA-E have identified five major glycoprotein bands (of apparent molecular weights of 116, 79, 64, 61, and 57 kDa) in the microsomal fraction of testosterone plus 17beta-estradiol (T + E2)-treated lateral prostate. These lectin-reactive bands were not detected in the AIT extracts. In the AIT microsomal extract, two glycoprotein bands of molecular weights of 58 and 46 kDa were revealed by SBA and PNA.

CONCLUSIONS

The present study shows that there is an increased expression of GalNAc(alpha1,3)GalNAc/Gal residues and triantennary complex-type oligosaccharides in the dysplastic epithelial cells as compared to normal secretory epithelial cells in rat lateral prostate. This altered expression of glycoconjugates revealed in the dysplastic epithelium indicates an aberrant glycosylation in the early premalignant stage of prostate carcinogenesis. The results also show that the AIT tumor cells are heterogeneous in their glycoconjugates and different from the dysplastic epithelial cells.

Glycoconjugates of the rat ciliary body epithelium: a lectin histochemical and protein blotting study

The present study sought to identify and partially characterize the glycoconjugates specific to the double-layered ciliary body epithelium of the rat eye by lectin histochemistry and lectin blottings. Hydrated paraffin sections of Carnoy-fixed Sprague-Dawley rat eyes were stained with a panel of 21 different biotinylated lectins, followed by streptavidin-peroxidase and the glucose oxidase-diaminobenzidine-nickel staining procedure. The results of lectin histochemistry revealed that the inner epithelial layer was rich in GlcNAc(beta1,4)GlcNAc, alpha-Gal, Gal(beta1,3)GalNAc, GalNAc(alpha1,3)GalNAc/Gal, GalNAc(alpha1,6)Gal, Fuc(alpha1,2)Gal(beta1,4)GlcNAc and Gal(beta1,4)GlcNAc(beta1,2)Man(alpha1,6) sugar residues as shown by its positive reactivities with S-WGA, PWA, DSA, GS-I-B4, PNA, DBA, SBA, WFA, UEA-I, LTA and PHA-E. The reactivities of GS-I-B4, PNA, DBA and SBA were restricted to the inner layer at the tips of the ciliary processes. On the other hand, the outer epithelial layer was stained evenly by DSA and Jacalin, and partly by MAA, showing that this epithelial layer was rich in GlcNAc(beta1,4)GlcNAc, Gal(beta1,3)GalNAc and NeuAc(alpha2,3)Gal disaccharides. These lectin binding patterns of the ciliary body epithelium suggest a topographical and functional difference in this double cell-layered epithelium. Their possible roles in the secretion of aqueous humour and production of ciliary zonule are discussed. Some identified lectin markers specific to these two cell layers may be useful for further experimental studies. Glycoproteins extracted from the dissected ciliary body were separated by SDS-PAGE electrophoresis and analyzed by protein blottings with 8 different lectins. The results showed that at least 10 major membrane-bound glycoproteins, with molecular weights ranging from 30 to 150 kD, rich in beta-GlcNAc, beta-Gal, alpha/beta-GalNAc and NeuAc(alpha2,6)Gal residues, were present in the microsomal fraction.

Comparative study of glycoconjugates of the rat prostatic lobes by lectin histochemistry

BACKGROUND

The rat prostate gland is composed of several distinct lobes: the ventral, lateral, dorsal, and anterior (also called the coagulating gland). Each prostatic lobe is different in its morphology, secretions, and response to hormones.

METHODS

The present study characterized and compared the expression of glycoconjugates in three different lobes (ventral, lateral, and dorsal) of the Noble rat prostate gland by lectin histochemistry, using a battery of 30 different lectins.

RESULTS

The results indicate that different prostatic lobes elaborate and secrete different glycoconjugates. The dorsal prostatic epithelium secretes mainly in an apocrine mode, as characterized by the presence of apical cytoplasmic blebs which are absent in the other two lobes, though merocrine secretion is also suggested. These cytoplasmic blebs were rich in Man, GlcNAc, Gal/GalNac, Fuc, NeuAc(alpha2,6)Gal, and oligosaccharides. Two types of cytoplasmic belbs were also identified according to their lectin bindings: blebs stained by S-Con A, LCA, PWA, UEA-II, RCA-I, DBA, ECA, WFA, Jacalin, MPA, SJA, LTA, UEA-I, PHA-E, and PHA-L, and some blebs stained by S-WGA, SBA, HAA, HPA, VAA, BPA, MAA, and SNA. The lectins, which reacted with the second type of blebs, also revealed some cytoplasmic granules in the dorsal prostatic epithelial cells. The epithelium of the lateral prostate showed weak or negative reactions to lectins, suggesting that it may express fewer glycoconjugates as compared to the other two lobes. The epithelial Golgi region of the ventral prostate is the most developed among the three lobes, and contained abundant GlcNAc, alpha/beta-GalNAc, and NeuAc(alpha2,6)Gal residues, as shown by its intense reactions to S-WGA, DBA, SBA, HAA, HPA, WFA, and SNA. GS-I-B4 reacted specifically with the basal epithelial cells in all three lobes, indicating that glycoconjugates with terminal alpha-Gal/GalNAc were commonly expressed in these basal cells. The basal cells in ventral prostate might express more complex glycoconjugates, as they were also stained by PWA, RCA-I, ECA, and PHA-L, in addition to GS-I-B4, suggesting that these basal cells contained more Gal(beta1,4)GlcNAc and Gal(beta1,4)GlcNAc(alpha1,2)Man residues. GS-I-B4 and PHA-L also demonstrated a differential staining of the stromal smooth muscles and their associated extracellular matrix in the three prostatic lobes, suggesting that these structural components in different prostatic lobes were different in their complex oligosaccharide contents, which probably has an influence on the epithelial-stromal interaction in the prostate.

CONCLUSIONS

In summary, the present study has established for the first time the expression patterns of glycoconjugates in the three lobes of the Noble rat prostate gland and suggests that certain lectins are useful as histochemical markers for the three individual prostatic lobes.

Characterization of glycoconjugates of guinea pig seminal vesicle by lectin histochemistry

In the present study, the expression of glycoconjugates in the guinea pig seminal vesicle was localized and partially characterized by lectin histochemistry using a battery of 30 different lectins specific for different carbohydrate residues. The results indicate that the glandular epithelium of the guinea pig seminal vesicle exhibits complex glycoconjugates rich in Man, beta-GlcNAc, beta-Gal, alpha/beta-GalNAc, Fuc and complex NeuAc(alpha2,6)Gal/GalNAc residues, as shown by its positive reactions to most lectins used. The Golgi region of the luminal secretory epithelial cells expresses a complex glycoconjugate pattern, as shown by its strong reactions to Man-(PSA, GNA), beta-GlcNAc-(S-WGA, PWA, DSA, UDA), beta-Gal-(RCA-I and -II), alpha/beta-GalNAc-(SBA, Jac, VVA, BPA) and complex NeuAc-(SNA) specific lectins, indicating that the secretory epithelial cells are active in glycosylation and secretion process. It was also shown in the present study that the basal and luminal epithelial cells are different in their glycoconjugates. The basal epithelial cells are rich in NeuAc(alpha2,3)Gal residues as they are stained specifically by MAA. The fibroblasts in the epithelial-smooth muscle interface and the smooth muscle cells close to the glandular epithelium are shown to express more glycoconjugates as they are stained intensely by GS-I-B4, GS-II and SBA. However, their role in the epithelial-stromal interaction in the seminal vesicle remains to be elucidated. In summary, the present study reports for the first time on the lectin binding patterns of the guinea pig seminal vesicle, and the results show that the seminal vesicle epithelium elaborates and secretes glycoconjugates in a complex pattern. Some of the lectins might be useful as histochemical markers for the secretory activity and specific structural components in the guinea pig seminal vesicle.

Effects of p-nitrophenyl-beta-D-xylopyranoside (beta-D-xyloside) on the androgen-induced growth of the lateral prostate of the prepubertally castrated guinea pig

The aim of this study was to examine the effects of beta-D-xyloside (XYL), a compound which interferes with stromal proteoglycan (PG) synthesis, on androgen induced growth of the lateral prostate (LP). Young male guinea pigs were castrated at 3 weeks of age and divided into three groups 6 weeks after castration. In group one, the animals were injected subcutaneously daily with 80 mg/kg of XYL, followed 3 days later by a daily dose of 10 mg/kg of dihydrotestosterone (DHT) for 2 more weeks. The second group served as control and received DHT only. In the third group, animals were treated first with XYL, like those in group one, and then followed by DHT alone for 2 weeks to check reversibility of the XYL effect. At the end of the experiment, the lateral prostate was removed and processed for morphological and cytochemical examination. The results showed that XYL inhibited the DHT stimulated growth of the lateral prostate. The fibroblasts showed a dilated granular endoplasmic reticulum filled with granular substances. In the interstitial spaces, there was a drastic increase in Cuprolinic Blue (CB) positive filaments and polygonal granules believed to be PGs or glycosaminoglycans (GAGs). Their number was much greater than the control. The distribution and density of the collagen fibers appeared similar to the control. The secretory alveoli were lined by epithelium with few secretory granules of low electron density and a larger number of clear vesicles. There was a slight reduction in glycoconjugate reactivities in the epithelial cells. The lectin binding patterns and the structural features were comparable between the control and recovery groups, indicating the XYL effects were reversible. The results suggest that stromal PG biosynthesis may play a role in epithelial function and an altered stromal matrix would hamper the effects of DHT on the target organ.

Effects of cis-4-hydroxy-L-proline on the androgen-induced growth of the lateral prostate of the prepubertally castrated guinea pig

The present study examined the effects of cis-4-hydroxy-L-proline (CHP), a proline analog, on the androgen-induced growth of the lateral prostate of prepubertally castrated guinea pigs. Prepubertal male guinea pigs were castrated at the age of 3 weeks and allowed to recover completely before subjection to an experimental regime to alter the stromal collagen synthesis by CHP. The animals were kept on a special proline-deficient diet (PDD) for a week before the subcutaneous injection of CHP (200 mg/kg/day) for 3 days, followed by a combined injection of CHP and dihydrotestosterone (DHT) (10 mg/kg/day) for 10 days. Control animals were injected with saline and DHT only. At the end of the experiment, the lateral prostate was removed and examined by 1) conventional transmission electron microscopy (TEM), 2) staining of proteoglycans (PGs) by Cuprolinic Blue (CB) using the critical electrolyte concentration (CEC) method, 3) carbohydrate and lectin histochemistry, and 4) electron microscopy (EM) lectin-gold labelling. The results showed that the wet weight of prostate from CHP-treated animals was significantly lower than the control and recovery groups. The epithelium was low columnar with an obvious increase in intercellular spaces and number of basal cells. The glandular cells showed little secretory activity with a decrease in number of granular endoplasmic reticulum (GER) profiles, secretory granules, and a small Golgi apparatus. The stroma was composed of stromal cells separated by large intercellular spaces with very sparse collagen fibrils, and a decrease in stromal PGs especially those PGs normally associated with collagen fibrils. CHP treatment also caused perturbation and disorganization in the epithelial basement membrane. The results suggested that stromal collagen is essential in mediating the response of glandular cells to DHT stimulation. Defective stromal collagens hamper the responsiveness of prostatic gland to androgen.