Collagen and cellular proliferation in spontaneous canine benign prostatic hypertrophy

PROSTATIC TISSUE ABLATION BY INJECTION: A LITERATURE REVIEW

PURPOSE

Most men 50 to 80 years old will have development of some degree of benign prostatic hyperplasia (BPH). Many who experience lower urinary tract symptoms (LUTS) will be treated medically. However, significant numbers will have more severe and progressive disease requiring surgery. Transurethral resection of the prostate is the current gold standard of treatment for BPH. Minimally invasive therapies for symptomatic BPH emerge and fade continuously. However, intraprostatic injection for BPH has been used for more than 100 years and may be on the verge of a rebirth. The goal of this review is to familiarize the reader with the origins and history of intraprostatic injection, and its evolution using transperineal, transrectal and transurethral routes with multiple injectants. Initially used to treat urinary retention in men with BPH, its primary indication is now for LUTS.

MATERIALS AND METHODS

We performed a structured MEDLINE review of the literature on intraprostatic injections from 1966 to 2003, augmented with relevant articles from select journals and documents dating to 1832.

RESULTS

In patients with BPH transperineal and transurethral injections have the most systematic evaluation. Most injectants will cause localized prostatic necrosis and gland volume reduction with varying degrees of LUTS relief. Anhydrous ethanol is the most widely studied injectable to date. There are advantages and disadvantages associated with each route of injection.

CONCLUSIONS

Examined for more than a century, the potential for using injectables for prostatic tissue ablation remains significant. More systematic laboratory research and clinical trials, currently ongoing, need to be completed.

Increased growth factor production in a human prostatic stromal cell culture model caused by hypoxia

BACKGROUND

Local hypoxia may be one of the triggers of embryonic reawakening of the stroma and subsequent hyperplastic growth in the prostate. Using a cell culture model of human prostatic stromal cells, we investigated the effects of hypoxia on activation of hypoxia-inducible factor 1 (HIF 1) and on the production of growth factors.

METHODS

Primary prostatic stromal cells were grown in normal and hypoxic (1% O(2)) atmosphere. Activation of HIF 1 was evaluated after different time intervals by Western blot. Induced secretion of growth factors VEGF, FGF-7, TGF-beta, IL 8, and FGF-2 were analyzed by ELISA. To confirm the in vitro findings we also performed immunohistochemistry of HIF 1alpha as well as pro-collagen I, collagens I, III, and IV in the benign tissue of radical prostatectomy specimens.

RESULTS

HIF 1 is activated in a time-dependent manner, already starting 1 hr after exposure of stromal cells to hypoxic conditions. Secretion of VEGF, FGF-7, TGF-beta, FGF-2, and IL 8 is increased under hypoxic in vitro conditions in comparison to normoxia. Levels of TGF-beta, VEGF, and IL 8 were rapidly and statistically significantly increased in the supernatant of hypoxic cells. Consistent with the in vitro findings, immunohistochemistry of HIF 1alpha in (benign prostatic hyperplasia) BPH tissue revealed strong HIF 1alpha nuclear staining in hyperplastic areas. No difference was observed in the collagen pattern between hyperplastic and normal prostate tissue.

CONCLUSIONS

Prostatic stromal cells respond to hypoxia by upregulation of secretion of several growth factors suggesting that hypoxia can trigger prostatic growth. Therefore, hypoxia might be a key factor contributing to the pathogenesis of BPH.

Growth factors and epithelial-stromal interactions in prostate cancer development

Epithelial-stromal interactions are important not only in growth, development, and functional cytodifferentiation of the prostate but also in derangements of prostate gland such as BPH and prostate carcinoma. This chapter explores the roles of epithelium and stroma during this delicate process and highlights the role and mutual influence of each on the other. It also examines the importance of ECM in mediating the effects of androgens and drawn attention to estrogen and genetic factors in the process. During this process of epithelial-stromal interaction, growth factors play a central role in mediating the interactions. This chapter focuses on the role of several growth factors including epidermal growth factor, fibroblast growth factor, transforming growth factor alpha, transforming growth factor beta, insulin-like growth factor-1, vascular endothelial growth factor, nerve growth factor, platelet-derived growth factor, and hepatocyte growth factor. This chapter emphasizes the importance of epithelial-stromal interactions in tumorigenesis and highlights the switch of paracrine to autocrine mode during the process of carcinogenesis.

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.

Quantitative changes in the morphology of the aging canine prostate

Stereological methods at the light and electron microscopic levels were used to examine the morphological changes in the beagle prostate associated with increasing age and with the occurrence of spontaneous benign hyperplasia. Analyses of semithin sections of tissue embedded in plastic revealed that proliferation of prostatic glandular and stromal components, increase in epithelial cell numbers, and increase in epithelial cell size all contributed to the dramatic increase in prostate weight seen in aging dogs. Analyses at the electron microscopic level revealed that the volume densities of rough endoplasmic reticulum and secretion granules were significantly lower in epithelial cells of the immature prostate than in the prostate of mature dogs (greater than 1.5 years of age). In contrast, no significant differences were seen in the volume densities of rough endoplasmic reticulum, free ribosomes, secretion granules, smooth endoplasmic reticulum, or mitochondria in randomly selected prostatic epithelial cells of dogs 1.5 to 9 years of age, whether or not the prostates were hyperplastic.

The hormonal maintenance and restoration of guinea pig seminal vesicle fibromuscular stroma

Using the separated epithelium and muscle preparation of the guinea pig seminal vesicle, we designed studies to investigate the hormonal control of epithelial collagen, muscle collagen and muscle cells. All hormone treatment regimens involved a comparison of the effects of hormone maintenance (homrone treatments initiated on the day of castration) versus hormone restoration (hormone treatments initiated after a castration-induced regression) on these 3 components of the fibromuscular stroma. In the epithelium, castration induced a 35 per cent decline in collagen content, which was either returned to normal by androgen restoration of prevented by androgen maintenance. In all androgen treatment regimens, changes in epithelial collagen correlated with changes in epithelial wet weight, cell number, RNA content and cell size. In contrast, growth of the epithelium was not stimulated by estrogen maintenance or restoration. Castration reduced muscle wet and dry weight, as well as cell size and RNA content, but there was no effect on cell number and collagen content. Androgen maintenance or restoration reversed the castration-induced regression in all parameters and also caused collagen content to increase 35 percent above normal. Estrogen maintenance of castrates sustained wet weight, dry weight and RNA content at normal and stimulated supranormal increases in both collagen content and cell number. Similarly, estrogen restoration induced supranormal increases in collagen content and returned RNA content to normal. However, estrogen's ability to stimulate supranormal increases in cell number and restore wet and dry weight to normal was lost after a castration-induced muscle regression. In summary, components of the guinea pig seminal vesicle fibromuscular stroma have been shown to be sensitive to androgens and/or estrogens. The action of androgen on these tissue components was independent of the state of tissue regression, whereas with the exception of RNA and collagen content all the effects of estrogen were significantly reduced with castration-induced regression of the tissue.