Reduction of endothelial and smooth muscle density in the corpora cavernosa of the streptozotocin induced diabetic rat

PURPOSE

Erectile dysfunction is one of the most prevalent complications of diabetes in males. Because adequate vascular perfusion is needed for appropriate erectile tissue function a likely reason for the high incidence of this complication in diabetics is a pathological change associated with the disease in vascularization of erectile tissues. We investigate whether chronic diabetes may induce changes in vascularization of the corpora cavernosa using a computerized image analysis system to quantify changes in the smooth muscle and endothelial cell content of the corpora cavernosa of diabetic rats induced by streptozotocin 6 months previously, and compare these changes to those associated with aging.

MATERIALS AND METHODS

We studied 3 groups of rats, including 10-week-old untreated controls, diabetic rats treated with streptozotocin for 6 months starting at age 10 weeks and 18-month-old rats (aged). Penile shafts from these groups were excised, fixed, sectioned and immunostained with anti-smooth muscle actin to identify smooth muscle cells and anti-CD31 to identify endothelial cells. Computerized image analysis was used to quantify the percent area within the corpora cavernosa occupied by smooth muscle cells or endothelial cells, and the data were compared among the groups.

RESULTS

We identified a highly significant decrease in the percentage of smooth muscle and endothelial cells within the cavernosa areas of diabetic rats compared to control or aged rats. Mean cavernous smooth muscle cell content was 15.28 +/- 2.54% in control rats and 9.83 +/- 1.21% in diabetic rats (p = 0.0001). Likewise, cavernous endothelial cell content was 6.93 +/- 0.86% in the control group and 4.01 +/- 1.08% in the diabetic group (p = 0. 0001). However, no statistical difference of smooth muscle or endothelial cell content was found between control and aged rats.

CONCLUSIONS

Using the streptozotocin treated rat as a model for diabetes, we showed that smooth muscle and endothelial cell density is significantly decreased in diabetic corpora cavernosa but not in normal aged rats. This observation is a further step toward the understanding of the pathomechanisms for diabetic related erectile dysfunction.

Herbal therapy PC-SPES: in vitro effects and evaluation of its efficacy in 69 patients with prostate cancer

PURPOSE

We investigate the potential use of the phytotherapeutic PC-SPES to treat human prostate cancer, and evaluate its in vivo and in vitro activity, and clinical efficacy.

MATERIALS AND METHODS

PC-SPES was evaluated for its ability to induce apoptosis on prostate cancer cell lines LNCaP, PC3 and DU145. The effect of oral PC-SPES on growth of PC3 tumors present in male immunodeficient mice was studied. A total of 30 male nude mice were divided in 5 groups. In groups 1 control and 2 full dose therapy was started the same day of the tumor injection. In groups 3 control, 4 half dose and 5 full dose PC-SPES therapy was initiated 1 week after tumor injection. A total of 69 patients with prostate cancer were treated with 3 capsules of 320 mg. PC-SPES daily. Serum prostate specific antigen (PSA) responses and side effects were evaluated.

RESULTS

All of the cultured prostate cancer cell lines had a significant dose dependent induction of apoptosis following exposure to an alcoholic PC-SPES extract. Immunodeficient mice xenografted with the PC3 cell line had reduced tumor volume compared with sham treated controls when they were treated with a PC-SPES extract from the time of tumor cell implantation (931 +/- 89 versus 1,424 +/- 685 mm.3, p not significant) but not when the treatment was begun 1 week after tumor cell implantation. The testis, prostate, bladder and seminal vesicles of the treated mice were significantly reduced in weight compared with the sham treated animals. Of the patients with prostate cancer 82% had decreased serum PSA 2 months, 78% 6 months and 88% 12 months after treatment with PC-SPES. Side effects in the treated patient population included nipple tenderness in 42% and phlebitis requiring heparinization in 2%.

CONCLUSIONS

An extract of the phytotherapeutic agent PC-SPES proved to be active in inducing apoptosis of hormone sensitive and insensitive prostate cancer cells in vitro, and in suppressing the growth rate of a hormone insensitive prostate cancer cell line in vivo. The overwhelming majority of patients with prostate cancer treated with the agent experienced a decrease in serum PSA but also demonstrated a side effect profile comparable to estrogen treatment.

Hypertension is associated with severe erectile dysfunction

PURPOSE

The prevalence and severity of erectile dysfunction in patients with hypertension need to be further evaluated. We evaluate medical and hypertension status, and erectile function in patients with hypertension.

MATERIALS AND METHODS

The International Index of Erectile Function, which is a detailed questionnaire, including well established components to evaluate patient medical history, hypertension status and erectile dysfunction, was mailed to 476 male patients of the outpatient Hypertension Center of Columbia Presbyterian Medical Center.

RESULTS

The questionnaire was completed by 104 (22.3%) patients, and mean age was 62.2 years (range 34 to 75). Of the patients 84.8% were sexually active and 68. 3% had various degrees of erectile dysfunction, which was mild in 7. 7%, moderate in 15.4% and severe in 45.2%. Compared to the general population of erectile dysfunction cases in the literature our study population with hypertension had a higher incidence of severe erectile dysfunction. Although correlations of antihypertensive medications with incidence of erectile dysfunction did not reach statistical significance, there was a clear trend with patients treated with diuretics and beta-blockers having the highest incidence and those treated with alpha-blockers having the lowest incidence of erectile dysfunction.

CONCLUSIONS

In addition to the observation that erectile dysfunction is more prevalent in patients with hypertension than in an age matched general population, our study shows that it is more severe in those with hypertension than in the general population.

The effects of androgen deprivation on the prostate gland: cell death mediated by vascular regression

Androgenic steroids are required to maintain the prostate gland in the adult state. Consistent with this requirement, androgen deprivation therapies typically induce a drastic regression of mature prostate tissue that is accompanied by the extensive loss of prostate cells through the programmed cell death process referred to as apoptosis. Whereas, in the past, the loss of prostate cells associated with androgen deprivation has generally been perceived to be a direct response of the androgen receptor-expressing prostate cells to an androgen-depleted environment, more recent studies of the prostate regression process suggest that it might instead be initiated by an indirect response of the prostatic parenchyma to an ischemic/hypoxic environment caused by a drastic reduction of blood flow to the tissue that occurs when androgens are withdrawn. This article reviews evidence that the prostatic vascular system is a primary target of androgen action and other evidence suggesting that the regression of the prostate parenchyma occurs secondarily to the regression of the prostate vascular system through cell death mediated by tissue ischemia/hypoxia.

Prostatic neoplasia in transgenic mice with prostate-directed overexpression of the c-myc oncoprotein

BACKGROUND

Promoter elements within the 5' DNA region of the rat C(3)1 gene have been shown to direct prostate-specific expression of gene products when they are fused through recombinant DNA procedures and used to produce transgenic mice. In order to test the in vivo effects of chronic overexpression of the mouse c-myc protooncogene on the prostate glands of transgenic mice, we created several lines of C(3)1-c-myc transgenic mice and then examined the phenotype of males with this genetic alteration.

METHODS

The modified promoter and 5' region of the rat C(3)1 gene was fused to the coding region of the mouse c-myc gene using recombinant DNA techniques. This DNA was used to create three different founder lines of transgenic mice. Tissues from males and females heterozygous for the transgene were examined for expression of the recombinant mouse c-myc mRNA by an RNase protection assay. Prostates from males were examined for expression of recombinant c-myc mRNA by in situ hybridization. Thin sections of fixed ventral prostates from males were analyzed by microscopy for histological abnormalities.

RESULTS

Three different lines of transgenic mice were obtained from these procedures. These mice demonstrated expression of recombinant mouse c-myc mRNA in the testis and ventral prostates of males and in the uterus of females. In situ hybridization demonstrated that the epithelial cells were the source of recombinant c-myc expression in the ventral prostates of the transgenic lines. Microscopic analysis of the ventral prostates from these mice demonstrated abnormalities in epithelial cell morphology seemingly typical of an intraepithelial neoplasia-like phenotype. However, none of the males of any of the lines developed overt prostatic adenocarcinoma over their lifetimes.

CONCLUSIONS

Chronic overexpression of c-myc in the ventral prostate epithelial cells of C3(1)-c-myc transgenic mice leads to the development of epithelial cell abnormalities similar to those seen in low-grade prostatic intraepithelial neoplasia in humans. These abnormalities were not found to progress to adenocarcinoma over the lifetimes of the transgenic mice, suggesting the need for additional oncogenic changes in the pathway to prostatic adenocarcinomas. Furthermore, our cumulative experience with the use of the C3(1) gene promoter in the generation of transgenic mice suggests that the probasin promoter element provides a much more specific and effective means to target transgenes to the prostate glands of mice.

Vascular endothelial growth factor-A expression in the rat ventral prostate gland and the early effects of castration

BACKGROUND

Blood flow to the rat ventral prostate gland is drastically reduced during the very early period after castration, and this reduction coincides with the appearance of striking degenerative changes within the prostatic vascular system. These early effects on the prostate vascular system are likely to be important for the subsequent regression of the ventral prostate that occurs in response to castration. Since the endothelial cells of the ventral prostate do not express androgen receptor protein (AR), we proposed that these early effects might be indirectly mediated by changes in the local expression of vascular regulatory factors. In order to evaluate whether vascular endothelial growth factor-A (VEGF-A) might be among the primary mediators of these effects, we measured expression of VEGF-A mRNA and protein in the rat ventral prostate gland prior to and within the first 3 days after castration.

METHODS

Ventral prostate tissues were obtained from control (unoperated) rats, sham-operated rats, or rats at sequential daily intervals (1-3 days) after castration. A quantitative RNase protection assay and a comparative RT-PCR assay were used to evaluate the extent to which the expression of VEGF-A mRNA in the ventral prostate was affected by castration. In situ immunohistochemistry, using an anti-VEGF-A antibody, was performed to localize VEGF-A protein in the various cells of the tissue. Western blot analysis and a quantitative ELISA assay using anti-VEGF-A antibodies were performed to determine how VEGF-A protein expression in the rat ventral prostate was affected by castration.

RESULTS

Results of VEGF-A mRNA analysis in the rat ventral prostate gland during the first 3 days after castration showed a biphasic change characterized by a transient reduction of VEGF-A mRNA expression (by approximately 50%) on the second day after castration that was restored to higher than control levels by the third day after castration. Immunohistochemical analysis for VEGF-A in control and castrated ventral prostates showed that the prostatic epithelial and smooth muscle cells were the major source of VEGF-A expression in this tissue. Quantitative analysis of VEGF-A protein expression by Western blot and ELISA methods confirmed a biphasic change in the expression of the polypeptide that correlated well with the results of the mRNA analyses.

CONCLUSIONS

VEGF-A expression in the ventral prostate gland of the Sprague-Dawley rat is downregulated on the second day after castration but returns to control levels by the third day after castration. Since critical changes in the ventral prostate vascular system are already evident by 1 day after castration, we believe that these findings indicate that VEGF-A is not likely to be the critical or sole mediator of the early effects of castration on the vascular system of the rat ventral prostate gland.

Current Concepts in Biomarker Technology for Bladder Cancers

Background: Transitional cell carcinoma of the bladder (TCC) is the second most common malignancy of the urinary tract. More than 70% of treated tumors recur, and 30% of recurrent tumors progress. Currently, pathologic staging and grading are valuable prognostic factors for detecting and monitoring TCC. Urinalysis, cystoscopy, and cytology are either invasive or lack sensitivity and specificity. The availability of a noninvasive, reliable, and simple test would greatly improve the detection and monitoring of patients with TCC. Several biomarkers for bladder cancer have been proposed, but no single marker has emerged as the test of choice.

Approach: We undertook a comprehensive literature search using Medline to identify all publications from 1980 to 1999. Articles that discussed potential biomarkers for TCC were screened. Only compounds that demonstrated high sensitivity or specificity, significant correlation with TCC diagnosis and staging, and extensive investigation were included in this review.

Content: Potential biomarkers of disease progression and prognosis include nuclear matrix protein, fibrin/fibrinogen product, bladder tumor antigen, blood group-related antigens, tumor-associated antigens, proliferating antigens, oncogenes, growth factors, cell adhesion molecules, and cell cycle regulatory proteins. The properties of the biomarkers and the methods for detecting or quantifying them are presented. Their sensitivities and specificities for detecting and monitoring disease were 54–100% and 61–97%, respectively, compared with 20–40% and 90% for urinalysis and cytology.

Summary: Although urine cytology and cystoscopy are still the standard of practice, many candidate biomarkers for TCC are emerging and being adopted into clinical practice. Further research and better understanding of the biology of bladder cancer, improved diagnostic techniques, and standardized interpretation are essential steps to develop reliable biomarkers. It is possible that using the current biomarkers as an adjuvant modality will improve our ability to diagnose and monitor bladder cancer.

Current concepts in biomarker technology for bladder cancers

BACKGROUND

Transitional cell carcinoma of the bladder (TCC) is the second most common malignancy of the urinary tract. More than 70% of treated tumors recur, and 30% of recurrent tumors progress. Currently, pathologic staging and grading are valuable prognostic factors for detecting and monitoring TCC. Urinalysis, cystoscopy, and cytology are either invasive or lack sensitivity and specificity. The availability of a noninvasive, reliable, and simple test would greatly improve the detection and monitoring of patients with TCC. Several biomarkers for bladder cancer have been proposed, but no single marker has emerged as the test of choice.

APPROACH

We undertook a comprehensive literature search using Medline to identify all publications from 1980 to 1999. Articles that discussed potential biomarkers for TCC were screened. Only compounds that demonstrated high sensitivity or specificity, significant correlation with TCC diagnosis and staging, and extensive investigation were included in this review.

CONTENT

Potential biomarkers of disease progression and prognosis include nuclear matrix protein, fibrin/fibrinogen product, bladder tumor antigen, blood group-related antigens, tumor-associated antigens, proliferating antigens, oncogenes, growth factors, cell adhesion molecules, and cell cycle regulatory proteins. The properties of the biomarkers and the methods for detecting or quantifying them are presented. Their sensitivities and specificities for detecting and monitoring disease were 54-100% and 61-97%, respectively, compared with 20-40% and 90% for urinalysis and cytology.

SUMMARY

Although urine cytology and cystoscopy are still the standard of practice, many candidate biomarkers for TCC are emerging and being adopted into clinical practice. Further research and better understanding of the biology of bladder cancer, improved diagnostic techniques, and standardized interpretation are essential steps to develop reliable biomarkers. It is possible that using the current biomarkers as an adjuvant modality will improve our ability to diagnose and monitor bladder cancer.

Acute increase in blood flow to the rat bladder subsequent to partial bladder outlet obstruction

Partial obstruction of the rat bladder outlet initiates a multi-step process during which the bladder progressively loses its functional ability. The first step in this progression is bladder hypertrophy; the organ dramatically increases in size and weight to compensate for the effects of obstruction. Unoperated female rats, age-matched, sham-obstructed rats, and rats that received a partial bladder outlet obstruction were studied. During the first 24 hours after partial bladder outlet obstruction, relative bladder blood flow was measured using a fluorescent microsphere infusion technique and laser Doppler imaging. Nitric oxide synthase (NOS) activities of control and obstructed rat bladder tissues were determined using an enzymatic assay that measures the conversion of (3)H-L-arginine to (3)H-L-citrulline. Using the microsphere infusion technique, a significant increase in blood flow to the obstructed rat bladder was observed during the first 24 hours after partial bladder outlet obstruction. Relative bladder blood flow increased approximately sixfold at 4 and 6 hours post-obstruction and remained elevated through 24 hours of obstruction. Sham operations (evaluated after 6 hours after surgery) resulted in a minor increase in blood flow that did not reach statistical significance. Relative blood flow to the spleen, measured in the same rats, was not significantly changed. Laser Doppler measurements also identified a significant increase in rat bladder blood flow after outlet obstruction and showed that increased blood flow could be detected as early as 1 hour post-obstruction. Interestingly, despite the significant differences in bladder blood flow between control and early post-obstructed rat bladders, NOS activities of control and obstructed rat bladders were comparable. The increase in bladder blood flow precedes the urothelial, fibroblast and smooth muscle cell hyperplasia, and the smooth muscle hypertrophy that occurs after obstruction. We propose that, in response to surgical induction of partial outlet obstruction, acute up-regulation of bladder blood flow may be an initiating factor for subsequent bladder cell proliferation and smooth muscle hypertrophy. Neurourol. Urodynam. 19:195-208, 2000.

Cryoablation for clinically localized prostate cancer using an argon-based system: complication rates and biochemical recurrence

OBJECTIVE

To determine the complication rates and biochemical recurrence after cryoablation of the prostate, using an argon gas-based system, in patients with localized prostate cancer.

PATIENTS AND METHODS

Between October 1997 and June 1999, 35 patients underwent cryoablation of the prostate (19 after radiation therapy failure and 16 as a primary treatment for localized prostate cancer). All patients had biopsy-confirmed prostate cancer with no seminal vesicle invasion, negative bone scans and a negative lymph node dissection. Patients received 3 months of combined hormonal therapy before cryosurgery. One surgeon performed all the procedures. Biochemical recurrence was defined by an increase in prostate specific antigen (PSA) of >/= 0.2 ng/mL above the PSA nadir.

RESULTS

The complications were rectal pain (26%), urinary infection (3%), scrotal oedema (12%), haematuria (6%) and incontinence (6%). Complication rates were higher in those patients who failed after radiation therapy than in those who did not receive radiation (incontinence 11% vs 0%, rectal pain 37% vs 12%) but the difference was not statistically significant. Twenty-two patients (63%) had an undetectable serum PSA nadir (< 0.1 ng/mL) after cryotherapy and 30 (84%) patients had a PSA value of < 1.0 ng/mL. After a mean follow-up of 8.3 months (range 0.2-18), nine patients had biochemical recurrence. The biochemical recurrence-free survival (BRFS) was 70% at 9 months. Patients who had an undetectable PSA nadir had a statistically higher BRSF at 9 months than did patients who had a detectable PSA nadir (89% vs 55%, respectively, P = 0.03). Similarly, patients with a preoperative serum PSA level of < 10 ng/mL had a statistically higher BRFS than patients who had a PSA level of > 10 ng/mL (86% vs 42% at 9 months, P < 0.001).

CONCLUSION

A PSA level before cryotherapy of < 10 ng/mL and an undetectable PSA nadir after cryotherapy were associated with the highest BRFS. Cryoablation of the prostate, with low morbidity, seems to be a viable option in managing patients by salvage therapy after radiation therapy and for the primary treatment of clinically localized prostate cancer.

Vascular anatomy of the rat ventral prostate

The rat ventral prostate gland is a model tissue to study the effects of androgenic steroids on prostate cells. Recent reports suggest that the prostatic vascular system is a primary target of androgen action in this tissue. In order to better understand how the vascular system of the ventral prostate supports the tissue in an androgenically normal adult male rat we utilized a variety of microscopic imaging techniques to more fully characterize its structural anatomy and its interaction with other prostatic cell types. Vascular corrosion casts were produced from the mature ventral prostate glands of rats. These casts were analyzed by scanning electron microscopy (SEM) to describe gross and fine details of the prostate vascular anatomy. Fixed thin sections of ventral prostates were immunostained with antiFactor XIII and analyzed by light microscopy for the presence of capillary elements within the prostatic glands. Other sections were directly analyzed by transmission electron microscopy (TEM) to describe the anatomical relationship between the capillaries and the prostatic ducts and their associated glands. The rat ventral prostate is supplied with blood by branches of the inferior vesical artery which enters the apex of the tissue from the base of the urinary bladder. Visualization of the prostatic vascular network under SEM shows that this major vessel is found on the posterior-medial surface of the tissue (closest to the bladder). This surface also has numerous serpentine vessels that appear to facilitate a stable blood supply to the prostate in accommodation of urinary bladder distension. Examination of the opposing surface of the casts allowed a crude description of the structure of the prostatic ductal system with the distal tips of the ducts (containing the prostate glands) oriented towards the anterior-lateral surface of the tissue. On this surface, one can discern a series of adjacent basket-shaped vascular structures of distributing arterioles that supply a dense complex of fine capillaries to the glands. Analysis of the interface of the prostatic ductal system with its vascular elements by light microscopy and TEM shows that some capillaries lie immediately adjacent to the basement membranes of the glands while others can be found interspersed within the myofibroblast layer surrounding the ducts and glands. Veins accompany the arteries and combine with the superior vesical before entering the common iliac vein. This study gives a comprehensive and detailed view of the microvasculature of the rat ventral prostate gland. The findings here will provide the basis for future experiments to evaluate how the ventral prostate vascular system changes in response to androgenic manipulation and to other pathological conditions.

Transdifferentiation of prostate cancer cells to a neuroendocrine cell phenotype in vitro and in vivo

PURPOSE

To better understand the source of neuroendocrine cells associated with human prostate cancer progression, we studied the ability of a cultured prostate cancer cell line, LNCaP, to transdifferentiate into neuroendocrine-like cells in vitro and in vivo.

MATERIALS AND METHODS

Cyclic AMP concentrations were measured in extracts of LNCaP cells cultured in the presence of normal or hormone-deficient medium (containing charcoal-stripped serum) with the use of an immunoassay. Quantitative RT-PCR procedures were used to determine whether hormone depletion affects TGF-beta2 mRNA expression. Western blotting procedures (for neuron specific enolase [NSE]) were used to determine whether TGF-beta2 supplementation or antibody neutralization might affect the ability of cultured LNCaP cells to transdifferentiate to neuroendocrine-like cells. Finally, tumors formed from LNCaP cells xenografted into male nude mice were evaluated for the presence of neuroendocrine cells (prior and subsequent to castration of the host mouse) using an immunohistochemical stain for chromogranin A.

RESULTS

LNCaP cells cultured in a hormone-deficient medium have a mean 9-fold increase in cyclic AMP (p = 0.02) and a significant decline in the expression of TGF-beta2 mRNA when compared with cells grown in normal medium. Supplementation or depletion of TGF-beta2 did not affect the neuroendocrine conversion of LNCaP cells as assessed by NSE expression patterns. LNCaP tumors growing in castrated male nude mice were found to have significantly increased numbers of chromogranin A positive neuroendocrine cells (46/high powered field) when compared with tumors growing in intact male mice (3/high powered field) (p = 0.0038).

CONCLUSIONS

Exposure of LNCaP cells to a hormone deficient medium drastically increased cyclic AMP production and this may identify the biochemical pathway through which hormone depletion induces a neuroendocrine conversion of prostate cancer cells. Hormone depletion also reduced TGF-beta2 mRNA expression and this finding was consistent with our inability to demonstrate any effect of TGF-beta2 on neuroendocrine conversion in vitro. Finally, our demonstration of increased neuroendocrine cells found in LNCaP tumors growing in castrated immunodeficient mice suggests that the neuroendocrine cells associated with advanced human prostate tumors in vivo, arise from prostate cancer cells through the transdifferentiation process.

Expression of VEGF splice variants 144/145 and 205/206 in adult male tissues

Currently, at least five different mRNA species encoding vascular endothelial growth factor-A (VEGF-A) have been characterized. These variants result from alternative splicing of the VEGF-A transcript and encode human isoforms of VEGF protein of 121, 145, 165, 189, and 206 amino acids. In the rat, a similar profile of VEGF-A splice variants has been described, each encoding one fewer amino acid than the human species. Studies of mammalian tissues have shown that these mRNA isoforms vary in abundance. Whereas VEGF 188/189, 164/165, and 120/121 (rat/human, respectively) are the predominant forms expressed in most tissues and cells examined, VEGF 144/145 and 205/206 are rare variants. Previously, VEGF 144/145 had been detected only in placental and uterine tissues and endometrial carcinoma cell lines, whereas VEGF 205/206 was detected only in fetal liver and placenta. Using an RT-PCR technique, cDNA cloning, and sequencing, we have detected and confirmed the presence of mRNA encoding VEGF 144/145 and 205/206 in both adult rat lung and penis. Therefore, these low-abundance VEGF splice variants have a more diverse expression pattern than originally predicted.

Castration induces acute vasoconstriction of blood vessels in the rat prostate concomitant with a reduction of prostatic nitric oxide synthase activity

PURPOSE

Previous studies demonstrating a rapid and drastic reduction of blood flow to the rat prostate gland resulting from castration caused us to consider the influence of castration on the state of vascular constriction and on the activity of the vascular tone-regulating factors (nitric oxide synthase and cyclic GMP) in the rat prostate.

MATERIALS AND METHODS

Sections of ventral prostate glands obtained from intact and castrated rats were analyzed for the mean areas within smooth muscle-coated blood vessels using a computerized microscopic image analysis system. Nitric oxide synthase (NOS) levels were measured in prostatic extracts from unoperated or castrated rats using an enzyme assay system that measures conversion of 3H-L-arginine to citruline. Cyclic GMP levels were measured in prostatic extracts from unoperated or castrated rats using a competitive radioimmunoassay system.

RESULTS

The mean area within ventral prostate smooth muscle-coated blood vessels was reduced 39% at 24 hours after castration (p = 0.039) and 47.7% at 48 hours after castration (p = 0.039). NOS activity measured in prostatic extracts was reduced 38% at 24 hours (p = 0.0012) and 51.6% at 36 hours after castration (p = 0.0001) compared with the control group of noncastrated rats. Finally, prostatic cGMP levels were reduced 55.8% (p = 0.0018) at 36 hours after castration when compared with controls rats.

CONCLUSION

Within 24 hours after castration, the lumenal areas of smooth muscle-coated blood vessels in the rat prostate gland were found to be significantly reduced. This vasoconstriction was associated with a significant reduction of prostatic NOS activity as well as a reduction in the prostatic levels of the NOS co-factor, cGMP. Thus, acute vasoconstriction is a prominent early event associated with rat prostate regression in response to castration and likely contributes to the regression of the tissue.

A recombinant defective adenoviral agent expressing anti-bcl-2 ribozyme promotes apoptosis of bcl-2-expressing human prostate cancer cells

Over-expression of bcl-2, a potent anti-apoptosis protein, is likely to be one of the genetic mechanisms through which human prostate cancer cells develop resistance to hormonal and other forms of therapy. To develop a therapeutic agent for hormone-resistant prostate cancer based on suppression of bcl-2 expression, we had previously designed and synthesized a dual-hammerhead ribozyme capable of recognizing and specifically cleaving human bcl-2 mRNA in vitro as well as in vivo. To increase the efficiency by which the anti-bcl-2 ribozyme can be delivered to target cells, we have created a recombinant replication-deficient (defective) adenoviral agent capable of expressing the anti-bcl-2 ribozyme upon infection. This viral agent effectively reduces intracellular levels of bcl-2 mRNA and protein in cultured LNCaP prostate cancer cells following standard infection procedures. Likewise, the defective adenovirus-anti-bcl-2 ribozyme induces extensive apoptosis in several androgen-sensitive (LNCaP) and androgen-insensitive (LNCaP/bcl-2 and PC-3) human prostate cancer cell lines that express differing amounts of bcl-2 protein. One androgen-insensitive prostate cancer cell line, DU-145, lacking in bcl-2 expression, was found to be completely refractory to the effects of the virus ribozyme, supporting the concept that the cytotoxic effects of the ribozyme are based solely on its effects on bcl-2 expression. Our results support further development of this adenovirus/anti-bcl-2 ribozyme for potential gene therapeutic purposes in certain forms of hormone-resistant prostate cancer where over-expression of bcl-2 proto-oncogene is indicated.

The microvascular architecture of the rat vagina revealed by image analysis of vascular corrosion casts

BACKGROUND

Female sexual dysfunction is a common but poorly understood human condition. One of the aspects hindering progress in this area is the lack of appropriate animal models that can be used to study the complex factors involved in this sexual health problem. Recently, attention has focused on the probable role of vascular dynamics of the genital organs and their potential for impact on female sexuality. The objective of this study was to provide a better description of the vascular anatomy of the female rat vagina and external genital organs in an attempt to better develop this as an animal model to study female sexual dysfunction.

METHODS

Young female (nonestrous) virgin rats were anesthetized, the abdominal aorta was cannulated, and the distal vasculature was flushed and fixed in vivo for histological studies or for subsequent infusion with Mercox resin for vascular corrosion casting. Vascular corrosion casts of the external genitalia (vagina and vulva) were studied using a scanning electron microscope (SEM). Fixed tissue specimens were also embedded and sectioned for histochemical and immunohistochemical analysis.

RESULTS

Scanning electron microscopy imaging allowed a description of the vascular and microvascular system of the nonestrous female rat genitalia. Major feeding vessels were located laterally in the muscular and serosal layers of the vagina with a complex system of interanastomosing collaterals between these large lateral trunks. The sub-epithelial region of the vaginal wall contains a dense and rich network of capillaries that perfuse the epithelium. These data were corroborated by two- dimensional histochemistry and immunostaining for endothelial and smooth muscle cells on paraffin-embedded thin sections of the female vagina and vulva.

CONCLUSION

This study provides the first detailed three-dimensional en bloc view of the macro- and microvascular anatomy of the female rat vagina and vulva. The findings suggest an active interaction between the microvasculature and the epithelial cells of the vaginal wall. This study will provide the basic anatomic groundwork for future experiments on perturbations of the vascular system of the rat female genitalia in response to hormonal stimuli and various disease states.

Fas antigen/CD-95 upregulation and activation during castration-induced regression of the rat ventral prostate gland

BACKGROUND

Fas antigen/CD 95 is a 45-kDa transmembrane protein that can initiate intracellular signaling pathways, leading to apoptosis when it is clustered on the cell surface. A recent report claiming that the ventral prostate glands of lpr -/- mutant mice (lacking functional fas antigen) do not regress following castration prompted our analysis of the regressing rat ventral prostate gland for evidence that fas antigen might participate in the molecular process leading to prostate cell apoptosis after castration.

METHODS

An RNase protection assay and Western blotting analysis were used to quantify fas antigen mRNA and protein expression in the regressing rat ventral prostate gland. Immunoprecipitates of fas antigen from membrane preparations made from control or castrated rat prostates were analyzed for coprecipitation of FADD and RIP proteins to assess the activation state of the fas antigen before and after castration. Finally, prostate tissues obtained from two different strains of lpr -/- mutant mice were analyzed for induced apoptosis after castration by the TUNEL staining method.

RESULTS

Rat ventral prostate gland fas antigen mRNA and protein expression was upregulated approximately 3-5-fold in the 3-day castrated rat as compared to hormonally intact rats. Immunoprecipitates of fas antigen from membranes of ventral prostates from castrated rats contained significantly increased amounts of both FADD and RIP proteins when compared to those of intact or control operated rats. However, counts of TUNEL-labeled cells in the ventral prostate glands of castrated lpr -/- mice were not significantly different from those in castrated, genetically normal controls. Likewise, the morphology of apoptotic bodies formed in the prostates of castrated lpr -/- mice was indistinguishable from that in control animals.

CONCLUSIONS

Fas antigen/CD-95, a protein that is involved in some forms of apoptosis, is upregulated during regression of the rat ventral prostate gland and becomes functionally "activated." However, our inability to distinguish any difference in the apoptosis rate or in the morphology of the apoptotic bodies formed in response to castration between lpr -/- mice and genetically normal controls indicates that, contrary to the prior report, functional fas protein is not required for castration-induced prostate cell apoptosis.

Unique morphological aspects of the rat ventral prostate gland revealed by vascular corrosion casting

BACKGROUND

There is growing interest as to the potential role of the prostatic vascular system in mediating the effects of androgenic steroids on growth control of the prostate. Here we describe the use of a vascular corrosion casting technique that enables the visual characterization of the vascular system of the rat ventral prostate and the description of some unique morphological features of the mature rat prostate gland that were never previously observed.

METHODS

Anesthetized adult male Sprague-Dawley rats were vascularly perfused with a fixative solution and then with a catalyzed methacrylate-based casting solution that was allowed to polymerize in situ. Ventral prostate glands were dissected from these rats and the tissues were subsequently dissolved in a corrosive solution, leaving residual vascular casts. The casts were then examined by scanning electron microscopy for pertinent morphological features.

RESULTS

Vascular corrosion casts of individual lobes of the mature rat ventral prostate revealed a complex vascular structure that entered into the prostate near the base of the bladder. The morphological correspondence of the prostatic vasculature to the previously described ductal organization of the prostate was readily apparent. Examination of the entire vascular complex (under low-power scanning electron microscopy) revealed three differing surface features of the tissue and suggested that the glandular elements of the ventral prostate were directionally oriented towards a single surface (the anterior-lateral surface). An opposing face (posterior-medial) of the tissue demonstrated some unique spiral vessels, suggesting the need for a potential stretch-compensation mechanism at the prostate surface immediately adjacent to the bladder.

CONCLUSIONS

Vascular casts of the rat ventral prostate gland reveal the obvious ductal organization of the prostatic parenchyma and demonstrate that these ducts are directionally oriented so that the glands of the prostate (at the distal tips of the ducts) uniformly lie near the anterior-lateral surface of the tissue. Unusual spiral arterioles found proximal to the bladder surface suggest that the rat ventral prostate gland has acquired the means to adapt to an anatomical position adjacent to a tissue (bladder) that acutely varies in size during the micturition cycle.

Expression of messenger ribonucleic acid splice variants for vascular endothelial growth factor in the penis of adult rats and humans

Erectile dysfunction is often associated with problems in vascular perfusion to the erectile components of the penis. In order to better understand the factors that control vascular formation and perfusion in the erectile tissues of the penis, we have begun to characterize the expression of vascular endothelial growth factor (VEGF) in penis tissues. VEGF is one of several polypeptides that have significant angiogenic activity in vitro and in vivo. Extensive characterization of the VEGF gene and its products has shown that several different mature mRNA transcripts exist, originating from alternative splicing of the basic VEGF transcript. These variant transcripts can encode peptides with different biological activities. Penile tissue was obtained from adult rats and from human patients undergoing penile prosthesis implantation. Analysis of the forms of VEGF transcripts was performed using a reverse transcription-polymerase chain reaction technique with primer pairs derived from the first and eighth exon of the VEGF gene. The expression levels of the various isoforms in the rat penis were then quantified using RNase protection assays. Four previously described splice variants of VEGF mRNA (VEGF 120, 144, 164, 188) were detected in rat and human penile tissues. In contrast to what is seen in the rat lung, where the most abundant form of VEGF mRNA is the 188 splice isoform, VEGF 164 is the most abundant transcript detected in the penis. Finally, sequence analysis of numerous VEGF cDNA clones obtained from the rat penis demonstrated the presence of a previously undescribed VEGF splice variant that could give rise to a protein of 110 amino acid residues (VEGF 110, GenBank accession no. AF080594). In summary, a number of VEGF mRNA isoforms are expressed in the rat and human penis, with the splice variant encoding a 164-amino acid protein present in greatest abundance. This study is a prelude to attempts to genetically manipulate VEGF expression in the penis as a therapy for erectile dysfunction.

Exisulind (sulindac sulfone) suppresses growth of human prostate cancer in a nude mouse xenograft model by increasing apoptosis

OBJECTIVES

Recent studies have shown that Exisulind, a sulfone metabolite of the nonsteroidal anti-inflammatory drug (NSAID) sulindac, has inhibitory activity in vitro with cultured human prostate cancer cells. To determine whether this effect might be pharmacologically relevant in vivo, we tested whether Exisulind therapy could suppress the growth of human prostate cancer cells in a nude mouse xenograft model.

METHODS

Thirty athymic nude mice were injected subcutaneously in the flank with 1 x 10(7) LNCaP human prostate tumor cells. All mice received a control diet for 21 days. One group of mice was continued on this control diet for an additional 4 weeks, a second group was switched to a diet supplemented with 0.05% Exisulind (40% of maximal tolerated dose [MTD]), and a third group was switched to a diet supplemented with 0.1% Exisulind (80% MTD) for the additional 4 weeks. Tumor growth was measured through the 4-week test period, and subsequently tissue sections from the various groups were tested for apoptotic and dividing cells by quantified use of the TUNEL assay and a bromodeoxyuridine (BrdU) incorporation immunoassay.

RESULTS

Tumors grew by 158%, 24%, and 18% for the control and 0.05% and 0.1% Exisulind groups, respectively (P = 0.02) during the 4-week test period. Immunohistochemical studies on excised tumors showed an increased number of apoptotic bodies in the treated groups versus the control group (P<0.0001) but no change in the number of BrdU positive cells.

CONCLUSIONS

This is the first study to show a direct in vivo effect of an NSAID-derived drug, lacking cyclooxygenase inhibitory activity, in a xenograft model of prostate cancer. Clinical studies to evaluate the effects of Exisulind against prostate cancer in humans are warranted.

Rapid reduction in blood flow to the rat ventral prostate gland after castration: preliminary evidence that androgens influence prostate size by regulating blood flow to the prostate gland and prostatic endothelial cell survival

BACKGROUND

Androgenic steroids regulate the development and size of the mammalian prostate gland. The mechanism(s) for this growth control might involve a direct effect on prostate cell proliferation and survival as well as more complex effects on the tissue environment supporting nourishment and oxygenation. In this study, we evaluated an animal model of androgen action on the prostate, the rat ventral prostate gland, to determine whether acute androgen withdrawal, by means of castration, might alter the primary blood flow to the prostate gland and for the effects of castration on prostatic endothelial cell viability.

METHODS

Groups of rats studied included intact control males, males that had been surgically castrated, or males that received a sham-surgical castration. Relative blood flow (RBF) to the rat ventral prostate glands and rat bladders were measured at 18 and 24 hr after castration or sham castration using a fluorescent microsphere infusion technique. Thin sections from fixed and embedded rat ventral prostate glands obtained from unoperated or 12-hr castrated rats were analyzed by the TUNEL immunostaining technique to microscopically identify and quantify apoptotic epithelial, stromal, and endothelial cells.

RESULTS

RBF to the rat ventral prostate was reduced by 38%, at 18 hr after castration when compared with intact or sham-operated rats and by 45% at 24 hr after castration (P=0.038 unoperated/0.025 sham operated). In contrast, RBF to the bladder was not significantly different between any of the groups in the 24-hr castrate experiment. TUNEL staining analysis of ventral prostate tissues obtained from 12-hr castrated rats showed only rare TUNEL-positive epithelial cells similar to the control tissue but significantly increased TUNEL labeling for endothelial and other ventral prostate stromal cells.

CONCLUSIONS

Castration resulted in a rapid and significant reduction of blood flow to the mature rat ventral prostate gland that was not seen in the bladder. This reduction precedes the appearance of apoptosis in the epithelial cells of the tissue but more coincided with the appearance of TUNEL-positive prostate vascular endothelial and stromal cells, suggesting that androgens support the survival of cells in the vascular and stromal compartment of the rat prostate as well as in the prostatic epithelium. These preliminary data support the concept that androgen action on the prostate might involve primary regulation of prostate blood flow and prostate vascular cell vitality.