In vivo model mimicking natural history of dog prostate cancer using DPC-1, a new canine prostate carcinoma cell line

BACKGROUND

Dog prostate cancer is usually considered to be highly relevant to human prostate cancer. We report the isolation of a new canine prostate cancer epithelial cell line designated DPC-1.

METHODS

Primary cultures were established from a canine poorly differentiated prostatic adenocarcinoma. Population doubling time was determined by counting nuclei after cell lysis. Tumorigenicity was assessed in nude mice and in one adult immunodeficient dog. Immunoscintigraphy was performed in both models using a monoclonal antibody (mAb) raised against the [44-62] sequence of human PSMA.

RESULTS

DPC-1 cells have a rapid growth in vitro (doubling time, 27 hr) which is not stimulated by androgens. In addition, DPC-1 displays immunoreactivity to human PSA and PSMA. DPC-1 was found to be highly tumorigenic not only in nude mice but also for the first time after orthotopic seeding in an immunodeficient dog. This allograft mimicked, in a compressed form, the aggressive biological behavior of spontaneous dog prostate adenocarcinoma. Immunoscintigraphy using a (131)Iodine-labeled PSMA mAb clearly visualized induced tumors in nude mice and in the dog allograft.

CONCLUSIONS

This study suggests that DPC-1 may constitute a powerful model for assessing new diagnostic and/or therapeutic tools in the management of prostate cancer.

Hereditary prostate cancer and other genetic predispositions to prostate cancer

The incidence of prostate cancer (CaP) and its increase in the last 10 years vary both from country to country and according to the ethnic group, with the highest incidence reported for Afro-Americans and the lowest for Asian men. To date, only three risk factors have been established for CaP: age; familial aggregation of CaP, and ethnic origins. No dietary or environment-related cause has been established. However, some variations in endogenous genetic factors may help explain differences in risk among ethnic groups or geographic areas. Similarly, certain genetic polymorphisms of genes encoding for 5alpha-reductase, androgen receptor or vitamin D, have been associated with different levels of CaP risk, and could explain the variations observed between populations. Different studies support the view that familial CaP may truly be hereditary, and not due to a similar lifestyle. Thus, familial inheritance is a parameter that needs to be considered in recommending screening for high-risk families. Indeed, when 1, 2, and 3 first-degree relatives are affected, the relative risk of first-degree relatives of CaP patients may increase to 2, 5, and 11%, respectively. Some familial forms appear to be associated with transmission of a rare putative dominant gene with a high penetrance (88% at age 85), with the cumulative proportion of CaP attributable to this gene being more marked for younger patients (a 43 versus a 34% risk of CaP appearing before the age of 55 versus 70 years). Using this transmission model and linkage analysis, a predisposing locus on chromosome 1q24-25 (HPC-1) has been described. Moreover, recessive and X-linked transmission has been suggested, showing that a large proportion of familial CaP may not be due to segregation of a few major gene mutations, but rather to familial sharing of alleles at many loci, each contributing to a small increase in cancer risk. Candidate genes may be the same suppressor genes that are involved in other cancers and in sporadic CaP.

Early-onset hereditary prostate cancer is not associated with specific clinical and biological features

BACKGROUND

Familial prostate cancer (CaP) accounts for 15-20% of all CaP, and hereditary CaP for 5-10% of patients. Few data are available concerning their clinical and biological features.

METHODS

We compared diagnostic modalities, age, clinical stage, PSA, and tumor grade at diagnosis in CaP patients according to familial CaP profile: hereditary (HR) (> or =3 CaP), familial nonhereditary (FNH) (= 2 CaP), and sporadic CaP. Only cases diagnosed after January 1, 1987 (PSA-available period) were included. We considered as informative sporadic (IS) cases those probands with 2+ nonaffected brothers at least 50 years old. Finally, 267 CaP (230 probands and 37 affected brothers) were studied.

RESULTS

In multivariate analysis, the only specific parameter significantly associated with HR and FNH CaP was early age at diagnosis; mean ages were 65.3 years (HR), 67 years (FNH), and 70.9 years (IS) (P < 0. 0001). No significant difference was observed concerning clinical stage, PSA, and tumor grade. In addition, diagnostic modalities were similar in the three groups.

CONCLUSIONS

Our data confirm the occurrence of early-onset CaP in hereditary families. Although the clinical and biological presentation of HR CaP remains controversial, the lack of specific features observed in our study leads us to conclude that there is no difference in the aggressiveness of the disease in hereditary compared to sporadic CaP.

A new prostatic stent for the treatment of benign prostatic hyperplasia in high-risk patients

OBJECTIVES

The objective of this study was to evaluate the efficacy and safety of a new prostatic stent (Trestle((R)), Boston Scientific Microvasive) for the treatment of BPH in patients with complete urinary retention and considered to be inoperable.

METHODS

The efficacy of the stent was evaluated in terms of return of micturition, level of patient satisfaction, uroflowmetry and residual urine. Any stents removed were examined by infrared spectrophotometry for the presence of crystalline encrustations.

RESULTS

From December 1997 to April 1999, 20 stents were inserted under local anaesthesia in 17 patients aged 54-90 years. Stents remained in place for an average of 3.5 months. Two migrations were reported. The mean maximum flow rate was 13.7 ml/s and the mean residual urine was 110 ml. The infrared spectrophotometry study revealed a glycoprotein film on stents in place for 1-6 months, accompanied by uric acid crystals on stents in place for 9 months.

CONCLUSION

The Trestle prostatic stent is effective and constitutes a good alternative to surgical treatment in patients with a high operative risk.

Early onset and familial predisposition to prostate cancer significantly enhance the probability for breast cancer in first degree relatives

Genetic predisposition accounts for >/=10% of all cancer of the prostate (CaP) and is therefore considered a major risk factor, together with age and ethnic origin. Several epidemiological studies have suggested that familial clustering of CaP may be associated with an increased frequency of breast and other cancers among relatives. In order to correlate the incidence of CaP with prevalence of breast and other cancers, we have performed uni- and multi-variate analyses on 691 complete pedigrees including probands, who were consecutive patients with confirmed CaP treated in three French urological departments. We have shown a significantly higher risk (RR = 2.3, p = 0.01) to develop breast cancer in families with multiple than in those with a single CaP. Risk of observing other types of cancer within these families was not significant. We then calculated the breast cancer risk in early onset prostate cancer families, and observed a relative risk that is even more significant (RR = 5.5, p = 0.002). Furthermore, the risk was >30 times that a proband's mother have breast cancer if CaP occurred below 55 years of age, rather than after 75 years (p = 0.003). This study has therefore shown for the first time, the relatively high penetrance for breast cancer in relatives of early onset CaP patients.

Gene transfer to urethral strictures in rabbits: a preliminary report

OBJECTIVE

To assess the rationale for virus-mediated gene transfer into the urethra in vivo and in vitro, using a rabbit model, as this is an attractive approach to prevent recurrence after the endoscopic management of urethral strictures.

MATERIALS AND METHODS

Primary cultures of rabbit urethral stromal cells were infected with adenoviral and retroviral solutions carrying a nucleus-targeted beta-galactosidase (beta-Gal) reporter gene (respectively 109 and 107 plaque-forming units/mL). In addition, to mimic the human clinical situation, a model was developed of thermally induced stricture in rabbit urethra which produced fibrotic stenosis within 15 days. Using a prototype channelled balloon catheter, these strictures were endoscopically dilated and then instilled with the beta-Gal adenoviral or retroviral constructs.

RESULTS

The application of recombinant adenovirus and retrovirus harbouring a nucleus-targeted beta-Gal reporter gene to cultured rabbit urethral stromal cells resulted in a high transduction efficiency of up to 90% and 96%, respectively. Five days after infection, histochemical and immunohistochemical staining of the strictured urethrae showed a 3% rate of transfection targeted to stromal cells within the fibrosis, confirmed by polymerase chain reaction (PCR) analysis. Adjacent and distal spread of the virus was excluded by histochemistry, immunohistochemistry and PCR.

CONCLUSION

These results represent the first report of endoscopic adenovirus and retrovirus-mediated gene transfer to the urethra. Although at a low rate, transduction reached stromal cells transmurally within the induced strictures and was site-specific.

htert expression correlates with MYC over-expression in human prostate cancer

Expression of the telomerase catalytic sub-unit (htert) constitutes a key step in the development of human cancer. Although htert regulation is still unclear, several studies suggest that c-myc may activate its expression. Prostate cancer is one of the most common malignancies among men in Western countries. Since de-regulated expression of myc as well as telomerase activation may contribute to the pathogenicity of this cancer, we investigated this pathway in prostate tumorigenesis. For this purpose, myc- and htert-mRNA expression was quantified in 33 sporadic prostate tumors using a real-time quantitative PCR assay based on TaqMan methodology. myc over-expression was observed in 19 (58%) of 33 tumors, whereas telomerase status evaluated by htert expression was observed in 22 (67%). There was no correlation between myc over-expression or htert expression level and tumor stage or Gleason grade. A significant association (p = 0.0024) was found between myc over-expression and elevated htert expression, indicating that the up-regulation of telomerase activity often observed in prostate tumors might be conferred through transactivation of htert by myc. It is likely that the ability of c-myc protein to stimulate expression of htert and thereby enhance telomerase activity represents an important step in prostate tumorigenesis.

VEGF overexpression in clinically localized prostate tumors and neuropilin-1 overexpression in metastatic forms

Studies comparing tumor neovascularity with pathological findings suggest that angiogenesis contributes to the pathogenesis of prostate cancer. We have examined 42 primary sporadic prostate tumors at different clinical stages, together with 3 prostate cancer cell lines (DU145, PC3 and LNCaP), for expression of VEGF and the gene encoding the recently identified VEGF165 isoform-specific receptor neuropilin-1, by using a quantitative reverse transcription (RT)-PCR method. We also evaluated the VEGF transcription pattern. Upregulation of VEGF and neuropilin-1 was observed in 12 and 14 tumors, respectively. The VEGF165 isoform was slighly overrepresented in tumors that overexpressed VEGF. VEGF overexpression correlated with stage II disease (p < 0.05); neuropilin-1 overexpression correlated with advanced disease (p < 0. 01) and a high Gleason grade (p < 0.02). Our observations suggest that VEGF expression could be used as a prognostic marker in early-stage prostate tumors, whereas neuropilin-1 overexpression might be a marker of aggressiveness.

Telomerase activity as a potential marker in preneoplastic bladder lesions

OBJECTIVE

To assess telomerase activity (involved in cell immortalization and detectable in most malignant tumours but not in normal somatic tissues) as a marker in cancer diagnosis.

PATIENTS AND METHODS

Tissue telomerase activity was assayed by two different techniques, the telomeric repeat amplification protocol-polymerase chain reaction (TRAP-PCR) and a telomerase PCR-enzyme linked immunosorbent assay. Malignant and inflammatory bladder lesions and their adjacent normal tissues were assessed for telomerase activity in a group of 18 patients, 14 of whom had urothelial carcinoma and four a nonspecific inflammatory lesion of the bladder.

RESULTS

Eleven of the 14 tumour samples analysed were telomerase-positive and two of the three telomerase-negative tumour samples had a detectable 'telomerase inhibitor'. In the apparently normal tissues next to bladder tumours, four of the 14 specimens were telomerase-positive. Interestingly, these lesions were always next to high-grade muscle-invasive bladder tumours (pT2G3). Two of the four nonspecific inflammatory lesions (one of cystitis glandularis and one of severe dysplasia), known to be preneoplastic lesions, were also telomerase-positive.

CONCLUSION

These results strongly suggest that the reactivation of telomerase may be an early event in bladder carcinogenesis, preceding morphological changes related to malignant transformation. Telomerase activity may therefore be useful both as an indicator of malignant potential in preneoplastic lesions, e.g. cystitis glandularis and severe dysplasia, and as a prognostic marker of bladder tumour relapse or progression.

[Genetic analysis of familial prostatic cancer: localization of a gene predisposing to prostatic cancer (PCaP) on chromosome 1q 42.2-43]

OBJECTIVES

To conduct genetic linkage analysis in order to localize predisposition genes for hereditary prostate cancer (CaP), as various epidemiological studies have demonstrated a family aggregation in 15 to 25% of cases, and the development of hereditary forms in 5 to 10% of cases of CaP.

MATERIAL AND METHODS

A genetic study on 47 French and German families included 122 patients and 72 subjects considered to be healthy after PSA assay. This study was conducted by linkage analysis of 364 microsatellite markers distributed throughout the genome (on average every 10 cM).

RESULTS

Parametric and nonparametric linkage analysis identified a locus on chromosome 1q 42.2-43, which could be with a gene predisposing to CaP (called PCaP). The primary site was confirmed by several markers, using 3 different genetic models. The maximum LOD score (probability of linkage between the locus and the disease) on two-point analysis was 2.7 for the D1S2785 marker. Parametric and nonparametric multipoint analysis provided an HLOD score and an NPL score of 2.2 and 3.1, respectively (with P = 0.001). Heterogeneity analysis with calculations of LOD scores by multipoint analysis estimated that up to 50% of hereditary CaPs were related to this locus, with a heterogeneity probability of 157/1. Analysis of a subgroup of 9/47 families characterized by early onset CaP (before the age of 60 years) confirmed the very high probability of localization of a predisposition gene at locus 1q42.2-43 for these families (multipoint LOD score and NPL score of 3.31 and 3.32, respectively; with P = 0.001).

CONCLUSION

The identification of predisposition genes will eventually allow identification within certain families of those subjects who have inherited the genetic abnormality and who therefore present a high risk of CaP. It will then be possible to perform targeted screening of CaP in order to diagnose CaP as early as possible.

[Comparison of biomechanical properties of the vaginal fixation in bladder neck suspensions according to the Burch technique and a percutaneous technique]

Bladder neck suspension or colpo-suspension can be performed via retropubic or percutaneous transvaginal approaches. A higher success rate is observed for retropubic procedures. One of the hypotheses proposed, but not yet verified, is that the retropubic approach allows better quality vaginal fixation than the percutaneous approach.

OBJECTIVE

The objective of this study was to compare the biomechanical properties of vaginal fixation according to the Burch procedure and according to a percutaneous technique (Vesica; Boston Scientific).

MATERIAL AND METHODS

We performed bladder neck suspension according to the Burch technique (2 points) on the left and according to the Vesica percutaneous technique on the right, on 6 fresh cadavers (mean age 8-5 years), using the same suture material. Vaginal fixations were subsequently excised. The depth of penetration into the vagina was measured and a computerized traction test (Lloyd Instruments, France) was performed on these fixations. The maximum force of traction before rupture was measured.

RESULTS

No significant difference was demonstrated for any of the measurements.

CONCLUSION

Vaginal fixation of bladder neck suspension performed according to the Burch technique or via a percutaneous technique (Vesica) present equivalent biomechanical properties.

[Epidemiology of familial prostatic cancer: 4-year assessment of French studies]

OBJECTIVES

(1) To determine the frequency of familial (at least 2 cases) and hereditary forms of prostate cancer (CaP), (2) to define the results according to the patient's age at diagnosis, as various epidemiological studies have demonstrated a possible familial aggregation of CaP in about 15 to 25% of cases. Carter's familial segregation study (P.N.A.S. 1992, 89, 3367-71) showed that a genetic predisposition, with autosomal dominant transmission, could be responsible for 9% of all cases of prostate cancer.

MATERIAL AND METHODS

We conducted a systematic genealogy study of patients suffering from newly diagnosed CaP or followed for known CaP in 3 French urological centres, by means of questionnaires completed by the patients. Subsequently, a national collection of families with at least 2 cases of CaP identified families with hereditary forms of CaP. Hereditary cases were considered to be those presenting at least: one CaP in three 1st degree relatives, or 3 cases over 3 generations in the same branch of the family (paternal or maternal), or finally 2 early cases before the age of 55 years. Statistical analysis used the univariate logistic regression test between family status and the medical centre or the patient's age at diagnosis.

RESULTS

From July 1994 onwards, we included 801 patients (all stages combined) in the systematic study and 110 patients (13.7%) were excluded (refusal to participate, advanced age). For 691 of the families studied (Brest: 225, Nancy: 249, Paris St Louis: 217), we observed 32 (14.2%), 29 (11.6%), 37 (17.1%) of familial forms (mean: 14.2%) and 11 (4.9%), 6 (2.4%), 8 (3.7%) of hereditary forms (mean: 3.6%), respectively (no significant differences between centres). Analysis of the results according to age at diagnosis of CaP also showed a higher incidence of familial (significant difference) and hereditary forms (limit of significance) for CaP occurring at a younger age (before 65 years). The national collection collected a total of 624 familial forms of CaP, including 236 (37.8%) cases of hereditary forms; 115 families were informative for the genetic linkage study.

CONCLUSION

These results confirm the data of earlier studies, revealing about 15 to 25% of familial forms of CaP and 5 to 10% of hereditary forms. Similarly, the systematic study confirmed the earlier onset of CaP in patients with a genetic predisposition. These data therefore encourage systematic questioning of patients for a family history of CaP in order to propose targeted screening of high-risk subjects in the families concerned and to intensify identification of hereditary forms in order to investigate the genes involved.

Expression and mutational analysis of the MADR2/Smad2 gene in human prostate cancer

BACKGROUND

Loss of heterozygosity (LOH) on chromosome arm 18q is common in sporadic prostate cancer and may be involved in cancer development through inactivation of tumor-suppressor genes (TSG). Recent identification, at 18q21.1, of MADR2/Smad2, a key component in transforming growth factor beta (TGFbeta)-family signaling pathways, led us to investigate the role of this gene in prostate tumorigenesis.

METHODS

Sporadic primary prostate tumors from 25 patients with clinically localized tumors and 7 with metastatic forms were examined for MADR2/Smad2 mutations by using polymerase chain reaction-single-strand conformational polymorphism (PCR-SSCP) analysis of cDNA, and for gene expression by quantitative reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

We detected no mutation in MADR2/Smad2 and no abnormal mRNA expression.

CONCLUSIONS

Despite recent evidence indicating that MADR2/Smad2 acts as a tumor-suppressor gene, our findings suggest a limited role of this gene in prostate tumorigenesis, at least in the early stages. Another key tumor-suppressor gene may therefore be the main target of the observed LOH at 18q21.1.

Vitamin D receptor polymorphisms as markers in prostate cancer

Polymorphisms in the vitamin D receptor (VDR) gene have been analyzed in several studies for an association with prostate cancer (PCA) and odds ratios (OR) > or = 3 have been observed in study populations from North America. We studied three polymorphisms in the VDR gene (poly-A microsatellite, TaqI and FokI RFLPs) in 105 controls and 132 sporadic PCA cases from France and in a collection of families from Germany and France. The polymorphisms near the 3' end of the gene were in linkage disequilibrium with an almost complete coincidence of the short poly-A alleles and t (presence of the restriction site) of the TaqI polymorphism, (contingency tables, P<0.0001). An association was found by logistic regression for the poly-A between PCA and the heterozygous genotype (S/L; S < 17, L > or = 17, OR=0.44, 95% confidence interval, CI=0.198-0.966, P=0.041). OR was lower in patients < or = 70 years old and patients with a Gleason score > or = 6. The Tt genotype of the TaqI RFLP also showed an association with PCA (OR=0.5, CI=0.27-0.92, P=0.026). This association was also stronger for patients < or = 70 years old (OR=0.31, CI=0.15-0.63, P=0.001). The risk alleles were S and t alleles as indicated by the OR of the homozygotes, although these were not significant. The FokI RFLP at the 5' end of the gene did not reveal any association (P>0.7). While some association studies differ between Europe and North America, our present findings with the VDR gene agree with those from North America, indicating a weak but general role of the VDR in PCA susceptibility.

FGF7/KGF triggers cell transformation and invasion on immortalised human prostatic epithelial PNT1A cells

Fibroblast growth factor 7 (FGF7/KGF) is synthesized exclusively by fibroblasts in normal tissues; it acts as a potent mitogen on epithelial cells, through interaction with the FGF7-specific receptor FGFR2/IIIb. To examine the importance of this growth factor both to prostate physiology and to prostate-cancer progression, we have tested the exogenous effect of FGF7. Thus, by mimicking the paracrine pathway (on proliferation, growth in soft agar and invasion) on the human prostatic epithelial cell line PNT1A positively checked for FGFR2/IIIb expression, FGF7 significantly enhanced cell proliferation at an optimal concentration of 7.5 x 10(-11) M, but no significant invasion or growth in soft agar were observed. To confirm FGF7 properties on human prostatic epithelial cells, we constitutively expressed FGF7 by transfecting PNT1A cells with FGF7-cDNA. The FGF7-transfected clones, PNT1A/ FGF7-T5 and PNT1A/FGF7-T6, were stable and expressed FGF7. Analysis of the FGF7-autocrine loop on the non-tumorigenic epithelial cells PNT1A showed acquired invasive potential in in vitro extracellular-matrix migration assays, specifically inhibited by an FGF7-neutralizing antibody, and over-expressed factors implicated in the migration process: the metalloproteinase MMP-1 and the plasminogen activator uPA. Taken together, these results demonstrate a role for FGF7 in triggering invasion of human prostatic epithelial cells. Furthermore, these FGF7-transfected clones exhibited functional and physiological differences from the original PNT1A cell line: anchorage-independent growth, growth in serum-free media and increased proliferation. These data confirm the oncogenic function of FGF7 in prostate progression potentially acting through paracrine and/or autocrine regulatory pathways.

FGF7/KGF triggers cell transformation and invasion on immortalised human prostatic epithelial PNT1A cells

Fibroblast growth factor 7 (FGF7/KGF) is synthesized exclusively by fibroblasts in normal tissues; it acts as a potent mitogen on epithelial cells, through interaction with the FGF7-specific receptor FGFR2/IIIb. To examine the importance of this growth factor both to prostate physiology and to prostate-cancer progression, we have tested the exogenous effect of FGF7. Thus, by mimicking the paracrine pathway (on proliferation, growth in soft agar and invasion) on the human prostatic epithelial cell line PNT1A positively checked for FGFR2/IIIb expression, FGF7 significantly enhanced cell proliferation at an optimal concentration of 7.5 x 10(-11) M, but no significant invasion or growth in soft agar were observed. To confirm FGF7 properties on human prostatic epithelial cells, we constitutively expressed FGF7 by transfecting PNT1A cells with FGF7-cDNA. The FGF7-transfected clones, PNT1A/ FGF7-T5 and PNT1A/FGF7-T6, were stable and expressed FGF7. Analysis of the FGF7-autocrine loop on the non-tumorigenic epithelial cells PNT1A showed acquired invasive potential in in vitro extracellular-matrix migration assays, specifically inhibited by an FGF7-neutralizing antibody, and over-expressed factors implicated in the migration process: the metalloproteinase MMP-1 and the plasminogen activator uPA. Taken together, these results demonstrate a role for FGF7 in triggering invasion of human prostatic epithelial cells. Furthermore, these FGF7-transfected clones exhibited functional and physiological differences from the original PNT1A cell line: anchorage-independent growth, growth in serum-free media and increased proliferation. These data confirm the oncogenic function of FGF7 in prostate progression potentially acting through paracrine and/or autocrine regulatory pathways.

Loss of heterozygosity at chromosome arm 13q and RB1 status in human prostate cancer

Aberrations of the long arm of chromosome 13 are common in prostate cancer and were initially attributed to alterations of the RB1 gene in band q14 of the chromosome. However, prostate tumors generally yield normal p110RB1 nuclear staining despite loss of heterozygosity (LOH) at the RB1 locus. Our previous analysis of chromosome arm 13q showed allelic loss in 41% of primary prostate tumors. To refine our knowledge of 13q, we extended our previous LOH study by using more polymorphic markers to analyze more prostate tumors. Sixty human prostate carcinomas were screened for allelic loss on 13q by using 13 13q-specific markers. LOH on the long arm of chromosome 13 was found in 39 (65%) of the 60 tumors. Furthermore, 33 of these 39 tumors had evidence of allelic loss involving a region of 13q14 containing RB1. Because immunohistochemical assessment of pRb expression is controversial in prostate tumors, we used a quantitative reverse transcription polymerase chain reaction (RT-PCR) method to determine whether RB1 is the target tumor suppressor gene in this region. RB1 mRNA steady-state levels were determined in 12 prostate tumors preselected on the basis of presumed deletion at the RB1 locus and four prostate tumors without LOH at the RB1 locus; five normal prostate specimens were used as controls. One of the 12 assessable prostate tumors with presumed LOH at RB1 showed a corresponding decreased in RB1 mRNA expression, whereas none of the four tumors without LOH at RB1 locus showed such a decrease. This study, based on another technical approach, confirms that RB1 is not the main target of the observed LOH at 13q14.3, and raises the possibility that another tumor suppressor gene in this region plays a key role in prostate cancer.

An experimental model of bulbar urethral stricture in rabbits using endoscopic radiofrequency coagulation

OBJECTIVES

To develop an experimental model of endoscopic urethral stricture mimicking the human clinical situation.

METHODS

Twenty-four New Zealand male rabbits were included. Eighteen animals (study group) underwent videourethroscopy with a pediatric resectoscope, and a 3 to 5-mm-long circumferential electrocoagulation of the bulbar urethra was performed, without postoperative urinary diversion. Six animals underwent the same procedure without application of electrocautery (control group). Each animal was assessed for urethral stricture on day 15 and day 30 by videourethroscopy and voiding cystogram. Among the study group, 8 animals were killed on day 15 and 10 on day 30 for histologic evaluation. All the control animals were killed on day 30 for histologic examination.

RESULTS

Nine animals (50%) in the study group developed a significant bulbar stricture (reducing the lumen by more than 50%) at day 15. Histologic examination confirmed the presence of hyalin fibrosis mutilating the urethral wall. No spontaneous improvement of the stricture was observed on day 30. None of the controls developed urethral stricture, and histologic examination showed a normal urethra in each case.

CONCLUSIONS

Endoscopic electrocoagulation of the urethral wall provides a reproducible model of stricture in the rabbit.

Ureteral gene transfer to porcine induced strictures using endourologic delivery of an adenoviral vector

PURPOSE

Direct gene transfer to the ureter is an attractive approach to prevent restenosis after endourologic management of ureteral strictures. We therefore assessed the rationale for adenovirus-mediated gene transfer in the ureter in vitro and in vivo using a porcine model.

MATERIALS AND METHODS

Primary cultures of porcine ureteral epithelial and stromal cells were infected with an adenoviral solution carrying a nucleus-targeted beta-Galactosidase (beta-Gal) reporter gene (6.5 10(8) pfu/ml.). In addition, in order to mimic the human clinical situation, we have devised a model of thermally-induced stricture in porcine ureter which produced tight fibrotic stenosis within 8 days. Using a purposely designed channelled balloon catheter prototype, these strictures were endoscopically dilated and then instilled with the same beta-Gal adenoviral construction.

RESULTS

Application of recombinant adenovirus harboring a nucleus-targeted beta-Gal reporter gene to cultured porcine urothelial and stromal cells resulted in high transduction efficiency of up to 99% and 84% respectively. Seven days after infection, X-Gal staining of the strictured ureters demonstrated transfection up to 2 mm. depth within the fibrosis, confirmed by polymerase chain reaction (PCR) analysis. Adjacent and distal spread of the virus was excluded by histochemistry (X-Gal staining) and PCR.

CONCLUSION

This data represents the first report of adenovirus-mediated gene transfer to the ureter. It remained site specific by endourologic retrograde clinically applicable techniques.

(CAG)nCAA and GGN repeats in the human androgen receptor gene are not associated with prostate cancer in a French-German population

Alleles of the CAG and the GGC repeat in the first exon of the human androgen receptor (AR) gene have been shown to be associated with the risk of (advanced) prostate cancer. These studies had been carried out in the United States. We have analysed these polymorphisms in a French-German collection of 105 controls, 132 sporadic cases, and a sample of prostate cancer families comprising 85 affected and 46 not affected family members. The allele distributions were very similar in all four groups and chi square statistics on contingency tables did not detect any significant differences. The relative risk (odds ratio, OR) were calculated using logistic regression and did not reach significance despite sufficient numbers of patients and controls. Typical results were OR = 1.007; 95% Confidence Interval (CI) 0.97-1.1, P = 0.87 for CAG as continuous variable and OR = 1.2 (95% CI 0.7-2.0), P = 0.47 for CAG classes < 22 and > = 22 repeats. Similar results were obtained for subgroups defined by age or Gleason score. We conclude that these polymorphisms can not be used as predictive parameters for prostate cancer in the French or German population.