Purification of enzymes of the kallikrein gene family (rK8 and rK9) from the rat prostate

Effect of Boerhaavia diffusa in experimental prostatic hyperplasia in rats

Objective:

Present investigation was undertaken to study the effectiveness of hydroalcoholic extract of roots of Boerhaavia diffusa in experimental benign prostatic hyperplasia (BPH) in rats using various animal models.

Materials and Methods:

BPH in rats was induced by subcutaneous injection of testosterone (5 mg/kg) daily for 28 days. Rats were divided in to five groups (six rats each). A negative control group received arachis oil (1 ml/kg s.c.) and four groups were injected testosterone. These four groups were further divided into reference group (finasteride 1 mg/kg), model group (testosterone), study group A (B. diffusa 100 mg/kg), and study group B (B. diffusa 250 mg/kg). On the 29^th day, rats were sacrificed and body weight, prostate weight, bladder weight, and serum testosterone level were measured and histological studies were carried out. Further in vitro analysis of B. diffusa extract on contractility of isolated rat vas deferens and prostate gland, produced by exogenously administered agonists were carried out. All results were expressed as mean ± SEM. 0 Data were analyzed by one-way analysis of variance followed by Tukey's test.

Results:

B. diffusa (100 mg/kg) treatment for 28 days resulted in significant inhibition of prostate growth (P < 0.05). Drug extract did not have significant change on serum testosterone level. Histopathological analysis of prostate gland supported above results. Results of in vitro experiment suggest that extracts had attenuated the contractile responses of isolated vas deferens and prostate gland to exogenously applied agonists.

Conclusion:

The results suggested that treatment with B. diffusa may improve symptoms of disease and inhibit the increased prostate size. In vitro study implies that herbal extracts has the machinery to produce beneficial effect on prostatic smooth muscle, which would relieve the urinary symptoms of disease. B. diffusa could be a potential source of new treatment of prostatic hyperplasia.

Altered expression of extracellular matrix and proteinases in Noble rat prostate gland after long-term treatment with sex steroids

BACKGROUND

Interactions between the epithelial cells and stromal tissues, which include the epithelial basement membrane, extracellular matrix, inducible factors, and various cell types, are believed to play a significant role in prostate gland carcinogenesis. Remodeling of extracellular matrix and degradation of basement membrane are the prerequisites for tumor cell invasion, and these changes are correlated with the expression of various proteinases.

METHODS

The present study examined the alterations of epithelial basement membrane, extracellular matrix, and proteinase activities in the Noble rat prostate gland after long-term treatments with androgen and estrogen (T+DES or T+E(2) for 4-12 months) by histochemistry, immunohistochemistry, electron microscopy, and gelatin-gel zymography.

RESULTS

After hormonal treatments, defects of epithelial basement membranes, such as focal disruption, diffuse staining and multilayering, were observed by histochemistry and immunohistochemistry in the dysplastic and neoplastic lesions induced in the lateral (LP) and ventral prostates (VP) but not in dorsal prostate (DP). An increase in the amount of extracellular matrix components, including hyaluronan (HA), chondroitin sulfate proteoglycan (CSPG) and tenascin, in the stroma of hormone-treated LP and VP was revealed by histochemistry and immunohistochemistry. Positive immunolabeling of matrix metalloproteinases 2 (MMP-2) and 9 (MMP-9) was detected in the fibromuscular layer surrounding the adenoma and adenocarcinoma induced in LP and VP after treatments with steroids for over 9-12 months. Zymography also detected an increase in activities of proteinases of apparent MW 120, 90, 86 and 68 kDa in the hormone-treated LP and VP, and these proteinases were characterized as metalloproteinases. In addition, two serine proteinases of MW 100 and 30 kDa were identified as being overexpressed in the hormone-treated LP and VP. Compared to LP and VP, there was no significant change in the proteinase activities in the hormone-treated DP.

CONCLUSIONS

The present study demonstrated that the epithelial basement membrane and stromal extracellular matrix were altered in dysplastic and neoplastic Noble rat prostates. Since HA and CSPG (or their complexes) are highly anionic molecules, their increased accumulation in the altered prostatic stroma would tend to hydrate this tissue. This would create an environment more favorable for tumor growth and invasion. These morphological changes were also correlated with the concurrent increase in gelatinolytic proteinase activities induced in these prostates. The results suggest that the remodeling of the stromal tissue might play a role in the early stage of prostate carcinogenesis as shown in the Noble rat model.

Purification and characterization of active recombinant rat kallikrein rK9

The rat tissue kallikrein rK9 is most abundant in the submandibular gland and the prostate. It has been successfully expressed in the Pichia pastoris yeast expression system. A full-length cDNA coding for the mature rK9 was fused in frame with yeast alpha-factor cDNA. The fusion protein was secreted into the medium with high yield without being processed by the yeast KEX2 signal peptidase. Mature rK9 was efficiently released from the fusion protein by trypsin and was purified to homogeneity by one-step affinity chromatography using soya bean trypsin inhibitor (SBTI) as affinity ligand. The identity of the recombinant enzyme was checked by N-terminal amino acid sequencing, Western blot analysis and kinetic studies. The dual trypsin- and chymotrypsin-like enzymatic specificity of rK9 was assessed by determining specificity constants (k(cat)/K(m)) for the hydrolysis of fluorogenic substrates, the peptide sequences of which were derived from proparathyroid hormone (pro-PTH) and from semenogelin-I. Our results confirmed the presence of an extended binding site in the rK9 active site. We also identified a far more sensitive substrate of this enzyme than those previously described, Abz-VKKRSARQ-EDDnp, which was hydrolysed with a catalytic efficiency k(cat)/K(m) of 420000 M(-1)s(-1). Finally, we showed that four of the five major proteins contained in secretions of rat seminal vesicles were rapidly degraded by recombinant rK9.

Expression of a kallikrein-like protein in prostatic intraepithelial neoplasia in ventral prostate of the noble rat

BACKGROUND

In an effort to identify biomarker(s) for prostatic cancer (PCa), we analyzed the changes of secretory proteins in the ventral prostate (VP) of Noble rats at early stages of carcinogenesis.

METHODS

Ventral prostates were removed from both control (n = 36) and experimental (n = 88) rats implanted with a known ratio of testosterone (T) and 17beta-estradiol (E(2)). Tissue sections were stained by hematoxylin and eosin (H&E) for pathological screening, and secretions were collected for SDS-PAGE analysis followed by N-terminal microsequencing, antiserum production, Western blot, and immunohistochemical study.

RESULTS

Pathologically, low-grade prostatic intraepithelial neoplasia (LGPIN) and high-grade PIN (HGPIN) were observed in ducts or alveoli after 3 and 5 months of T + E(2) treatment, respectively. The results of SDS-PAGE showed an elevated expression of 18-kDa protein (p18) in secretions of VP with HGPIN or cancerous lesions. Analysis of p18 by N-terminal sequencing showed a high score of homology to rat glandular kallikrein. To characterize the expression pattern of the protein in tissue samples, an antiserum was raised against the N-terminus of the p18. The monospecificity of the antiserum against p18 was confirmed by Western blot analysis. Immunohistochemical study showed that in ducts or alveoli of normal and LGPIN samples, a mild positive staining for p18 was observed in secretions. However, the reactivity was intense not only in luminal secretions but also in some luminal secretory cells in HGPIN and cancer cells as well.

CONCLUSIONS

The high expression of p18 in connection with neoplastic transformation of cells strongly suggests that the potential application of this protein as a marker for early detection of PCa should be further investigated.

Submandibular enzymatic vasoconstrictor increases DNA and phosphoinositol synthesis by mesenchymal cells

Submandibular enzymatic vasoconstrictor (SEV, rK9) induces vascular contraction and platelet aggregation by a mechanism requiring intact enzymatic activity. On the basis of a published report demonstrating growth-promoting enzymatic activity in an extract of the rat submandibular gland, we hypothesized that SEV would affect DNA synthesis. Recombinant SEV (rSEV), expressed in a baculovirus system, increased DNA synthesis 3- to 25-fold in Chinese hamster lung (CCL39) fibroblasts and in rabbit and rat vascular smooth muscle cells in a dose-dependent manner dose eliciting 50% of maximal response: 0.1-1 nM); this effect was inhibited by pertussis toxin (PTX). Inactive rSEV failed to enhance DNA synthesis. In CCL39 fibroblasts, rSEV increased total phosphoinositol (PI) formation (6- to 10-fold at 10 nM), which was inhibited 49% by PTX; it was also partially inhibited by the tyrosine kinase inhibitor genistein (33%) but was not affected by the protein kinase C inhibitor bisindolylmaleimide. These results show that rSEV increases DNA synthesis and PI formation in mesenchymal cells in a dose- and enzymatic activity-dependent manner through a pathway partially mediated by a PTX-sensitive G protein. Thus SEV can induce growth-associated responses, perhaps through a protease-activated receptor mechanism.

Kallikrein and kallikrein-like proteinases: purification and determination by chromatographic and electrophoretic methods

Kallikreins and kallikrein-like enzymes make up a family of serine proteinases present in tissues and body fluids of mammals and in some snake venoms. This review deals with the procedures of purification, detection and determination of these enzymes by chromatographic and electrophoretic methods. The procedures are reported in tables, described and discussed with the aim of illustrating the state-of-the-art of research in the field.