Mycophenolate mofetil-related enterocolitis and weight loss: a pediatric case series.

Mycophenolate mofetil (MMF) is an immunosuppressive medication utilized in the management of both autoimmune and solid organ transplant patients. Diarrhea is a common gastrointestinal side effect of MMF, but more severe forms of GI symptoms are described in renal transplant patients with a distinct pattern of histopathologic change, similar to graft-versus-host disease or Crohn's disease. This rare entity, commonly referred to as "MMF-related enterocolitis," has been described in adult patients, mostly in renal transplant patients, and in only two pediatric renal transplant patients. In previously reported cases, symptoms and abnormal histopathology improve with dose reduction of MMF. We describe a series of three pediatric patients with varied underlying disease process who presented with severe diarrhea and histopathologic findings characteristic of MMF-related enterocolitis, who share a novel finding of weight loss as a complication of MMF-related enterocolitis in pediatric patients.

No evidence for association of the MDM2-309 T/G promoter polymorphism with prostate cancer outcomes.

OBJECTIVES: Mouse double-minute 2 (MDM2) SNP309 polymorphism (T>G) has been correlated with an increased risk of cancer in multiple tumor types. MDM2 overexpression has shown to be weakly associated with distant tumor metastases, and down-regulation of MDM2 via antisense oligonucleotides in vitro has resulted in the radiosensitization of prostate cancer cell lines. Based on these results, we decided to evaluate the role of MDM2 SNP309 in the context of histopathologic parameters and clinical outcomes in prostate cancer tumors. MATERIALS AND METHODS: The population consisted of 212 consecutive prostate cancer patients who underwent radical prostatectomy between 1997 and 1999 at Vanderbilt University Medical Center. Two hundred eight of the samples were successfully genotyped for the MDM2 SNP309 polymorphism. Correlations between the polymorphism, recurrence, and survival data were analyzed using univariate and multivariate genetic models. RESULTS: The only prognostic factor predictive of overall survival in our study was Gleason score (P<0.005). Using χ(2) analysis, we determined that the MDM2 SNP309 polymorphism had no significant association with race (P=0.7512), patient's age at diagnosis (P=0.6820), pre-prostatectomy PSA level (P=0.8606), Gleason's score (P=0.4839), surgical margin status (P=1.0000), extracapsular extension (P=0 .6175), and disease stage (P=0.4945). In addition, there was no significant difference in 3-year recurrence-free survival (P=0.218), or 8-year overall survival (P=0.376). CONCLUSIONS: Our study finds no evidence for association of the MDM2 SNP309 polymorphism with clinicopathologic variables, recurrence risk, and overall survival outcome in prostate cancer.

Intestinal malrotation in an extremely preterm very low birthweight infant.

A case of a very low birthweight premature infant with a clinical presentation of necrotising enterocolitis that was found to have malrotation and midgut volvulus at autopsy is presented.

The matrix metalloproteinase-7 polymorphism rs10895304 is associated with increased recurrence risk in patients with clinically localized prostate cancer.

PURPOSE: To evaluate whether selected high-risk matrix metalloproteinase-7 single nucleotide polymorphisms influence clinicopathologic outcomes in patients with early-stage prostate cancer. METHODS AND MATERIALS: Two hundred twelve prostate cancer patients treated with radical prostatectomy were evaluated with a median follow-up of 9.8 years. Genotyping was performed using hybridization with custom-designed allele-specific probes. Three single nucleotide polymorphisms within the matrix metalloproteinase-7 gene were assessed with respect to age at diagnosis, margin status, extracapsular extension, lymph node involvement, recurrence-free survival, and overall survival in paraffin-embedded prostate tissue specimens from patients with early-stage prostate cancer who underwent radical prostatectomy. RESULTS: Rs10895304 was the sole significant polymorphism. The A/G genotype of rs10895304 had a statistically significant association with recurrence-free survival in postprostatectomy patients (p = 0.0061, log-rank test). The frequency of the risk-reducing genotype (A/A) was 74%, whereas that of the risk-enhancing genotypes (A/G and G/G) were 20% and 6%, respectively. Multivariable Cox regression analyses detected a significant association between rs10895304 and recurrences after adjustment for known prognostic factors. The G allele of this polymorphism was associated with increased risk of prostate cancer recurrence (adjusted hazards ratio, 3.375; 95% confidence interval 1.567-7.269; p < 0.001). The other assayed polymorphisms were not significant, and no correlations were made to other clinical variables. CONCLUSIONS: The A/G genotype of rs10895304 is predictive of decreased recurrence-free survival in patients with clinically localized prostate cancer. Our data suggest that for this subset of patients, prostatectomy alone may not be adequate for local control. This is a novel and relevant marker that should be evaluated for improved risk stratification of patients who may be candidates for adjuvant radiation therapy to improve local control.

Imperforate anus with a rectovestibular fistula and pseudotail: a case report.

INTRODUCTION: Human tails and pseudotails are rare sacrococcygeal lesions that are associated with a wide variety of anomalies and syndromes. Anorectal malformations are also relatively uncommon congenital defects that often occur in conjunction with syndromes or other congenital abnormalities. The anomalies associated with both disorders determine the timing and approach to surgical correction. We present an unusual case of a patient with both imperforate anus and a pseudotail in the absence of a syndrome or other associated anomalies and we emphasize the necessity of a thorough preoperative evaluation. CASE PRESENTATION: A Caucasian girl was born at term after an uncomplicated pregnancy and was noted at birth to have a skin-covered posterior midline mass and imperforate anus with a fistula to the vaginal vestibule. Ultrasound and magnetic resonance imaging revealed a predominately fatty lesion without presacral extension and ruled out associated spinal and cord abnormalities. The patient underwent diversion with colostomy and a mucous fistula in the newborn period as a fistulogram demonstrated a long fistulous tract to normal rectum and it was anticipated that anoplasty and resection of the mass would require extensive posterior dissection. The sacrococcygeal mass was removed during posterior sagittal anorectoplasty at the age of six weeks which was determined to be a pseudotail because of the composition of brown fat and cartilage. The patient is now 14 months old with normal bowel function after a colostomy takedown. CONCLUSION: A comprehensive preoperative assessment and thoughtful operative plan were necessary in this unusual case because of the extensive differential diagnosis for sacrococcygeal masses in the newborn and the frequency of anomalies and syndromes associated with tail variants and imperforate anus. The pediatricians and neonatologists who initially evaluate such patients and the surgeons who correct these disorders must be aware of the potential pitfalls in their management.

Comparative analysis of whole mount processing and systematic sampling of radical prostatectomy specimens: pathological outcomes and risk of biochemical recurrence.

PURPOSE: Whole mount processing is more resource intensive than routine systematic sampling of radical retropubic prostatectomy specimens. We compared whole mount and systematic sampling for detecting pathological outcomes, and compared the prognostic value of pathological findings across pathological methods. MATERIALS AND METHODS: We included men (608 whole mount and 525 systematic sampling samples) with no prior treatment who underwent radical retropubic prostatectomy at Vanderbilt University Medical Center between January 2000 and June 2008. We used univariate and multivariate analysis to compare the pathological outcome detection rate between pathological methods. Kaplan-Meier curves and the log rank test were used to compare the prognostic value of pathological findings across pathological methods. RESULTS: There were no significant differences between the whole mount and the systematic sampling groups in detecting extraprostatic extension (25% vs 30%), positive surgical margins (31% vs 31%), pathological Gleason score less than 7 (49% vs 43%), 7 (39% vs 43%) or greater than 7 (12% vs 13%), seminal vesicle invasion (8% vs 10%) or lymph node involvement (3% vs 5%). Tumor volume was higher in the systematic sampling group and whole mount detected more multiple surgical margins (each p <0.01). There were no significant differences in the likelihood of biochemical recurrence between the pathological methods when patients were stratified by pathological outcome. CONCLUSIONS: Except for estimated tumor volume and multiple margins whole mount and systematic sampling yield similar pathological information. Each method stratifies patients into comparable risk groups for biochemical recurrence. Thus, while whole mount is more resource intensive, it does not appear to result in improved detection of clinically important pathological outcomes or prognostication.

Bladder stromal loss of transforming growth factor receptor II decreases fibrosis after bladder obstruction.

PURPOSE: Transforming growth factor-beta is a potent stimulator of extracellular matrix production. Several studies show that loss of transforming growth factor-beta signaling decreases kidney, liver and lung fibrosis. However, the role of transforming growth factor-beta signaling in bladder fibrosis is not entirely understood. We investigated the effect of stromal loss of such signaling in mice after partial bladder outlet obstruction. MATERIALS AND METHODS: We performed partial bladder outlet obstruction by urethral ligation in 5-week-old female Tgfbr2(colTKO) mice. These mice were compared to WT mice with partial bladder outlet obstruction and to WT nonobstructed controls. After 4 weeks and before sacrifice urodynamics were performed. Bladder tissue was harvested, and p-Smad2 and collagen (Masson's trichrome) staining were performed. RESULTS: Bladder compliance was increased in partially obstructed Tgfbr2(colTKO) mice and decreased in partially obstructed WT mice. The latter had increased smooth muscle hypertrophy and increased collagen deposition between smooth muscle bundles compared to those in Tgfbr2(colTKO) mice and nonobstructed controls. Transforming growth factor-beta responsive collagen promoter activity was significantly decreased in Tgfbr2 knockout bladder stromal cells vs WT stromal cells. CONCLUSIONS: Stromal loss of transforming growth factor-beta signaling decreased collagen deposition after partial bladder outlet obstruction. In contrast to collagen production by recruited macrophages, stromal transforming growth factor-beta signaling appears to be the primary source of fibrosis after partial bladder outlet obstruction. These findings further support the hypothesis that manipulating transforming growth factor-beta signaling in bladder stromal cells would provide a future avenue for neuropathic bladder and bladder fibrosis treatment.

Recruitment of bone marrow derived cells to the bladder after bladder outlet obstruction.

PURPOSE: Bladder fibrosis is an undesired end point of partial bladder outlet obstruction. In fibrotic disease of the lung, kidney, skin and heart chemokines recruit bone marrow derived cells to injured tissue. Blockade of chemokines like CCL2 results in decreased fibrosis in other organs. To our knowledge we present the first report of bone marrow derived cell recruitment to the bladder in a murine bladder outlet obstruction model. MATERIALS AND METHODS: We lethally irradiated WT female mice and reconstituted their bone marrow using fetal liver cells from transgenic mice ubiquitously expressing green fluorescent protein. Periurethral collagen injection was used for bladder outlet obstruction. Obstruction was assessed by urodynamics, and bladder and kidney histological changes. Bladders were harvested 1 to 12 weeks after bladder outlet obstruction and compared to those in nonobstructed controls. The chemokine CCL2 was compared between obstructed and nonobstructed mice with reverse transcriptase-polymerase chain reaction. Green fluorescent protein expressing bone marrow derived cells were identified with immunohistochemistry and fluorescence activated cell sorting. RESULTS: Bladders showed histological and urodynamic changes consistent with obstruction. CCL2 induction increased after obstruction compared to that in controls. After obstruction bone marrow derived cells were present in the urothelial and stromal layers. Activated epidermal growth factor receptor was found in cells associated with bone marrow derived cells. CONCLUSIONS: Bone marrow derived cells are recruited to the bladder by bladder outlet obstruction and are present in the urothelial and stromal layers. Stromal bone marrow derived cells may have a role in hypertrophy and fibrosis. Further study of the recruitment and function of bone marrow derived cells in the bladder may provide potential targets for antifibrotic therapy.

Directed differentiation of bone marrow derived mesenchymal stem cells into bladder urothelium.

PURPOSE: We have previously reported that embryonic rat bladder mesenchyma has the appropriate inductive signals to direct pluripotent mouse embryonic stem cells toward endodermal derived urothelium and develop mature bladder tissue. We determined whether nonembryonic stem cells, specifically bone marrow derived mesenchymal stem cells, could serve as a source of pluripotent or multipotent progenitor cells. MATERIALS AND METHODS: Epithelium was separated from the mesenchymal shells of embryonic day 14 rat bladders. Mesenchymal stem cells were isolated from mouse femoral and tibial bone marrow. Heterospecific recombinant xenografts were created by combining the embryonic rat bladder mesenchyma shells with mesenchymal stem cells and grafting them into the renal subcapsular space of athymic nude mice. Grafts were harvested at time points of up to 42 days and stained for urothelial and stromal differentiation. RESULTS: Histological examination of xenografts comprising mouse mesenchymal stem cells and rat embryonic rat bladder mesenchyma yielded mature bladder structures showing normal microscopic architecture as well as proteins confirming functional characteristics. Specifically the induced urothelium expressed uroplakin, a highly selective marker of urothelial differentiation. These differentiated bladder structures demonstrated appropriate alpha-smooth muscle actin staining. Finally, Hoechst staining of the xenografts revealed nuclear architecture consistent with a mouse mesenchymal stem cell origin of the urothelium, supporting differentiated development of these cells. CONCLUSIONS: In the appropriate signaling environment bone marrow derived mesenchymal stem cells can undergo directed differentiation toward endodermal derived urothelium and develop into mature bladder tissue in a tissue recombination model. This model serves as an important tool for the study of bladder development with long-term application toward cell replacement therapies in the future.

Temporal-spatial protein expression in bladder tissue derived from embryonic stem cells.

PURPOSE: Identifying developmental proteins could lead to markers of bladder progenitor cells, which could be used to investigate bladder diseases. We recently reported a novel embryonic stem cell model in which to study differential protein expression patterns during bladder development. Differential and temporal expressions of the endodermal proteins known as forkhead box (Foxa1 and Foxa2) were observed. In the current study we further delineated these protein expression patterns. MATERIALS AND METHODS: Epithelium was removed from the underlying mesenchyma from embryonic day 18 rat bladders. Heterospecific recombinant xenografts were created by combining embryonic stem cells plus embryonic bladder mesenchyma and placed beneath the renal capsule of mouse hosts. Grafts were harvested at 16, 18, 21, 28, 35 and 42 days, and evaluated with hematoxylin and eosin, trichrome staining, and immunohistochemistry for uroplakin, smooth muscle alpha-actin, p63, Foxa1, Foxa2 and androgen receptor. RESULTS: At 16 days uroplakin was detectable and it seemed to correlate with the loss of Foxa2, while Foxa1 remained at all time points. Androgen receptor was first noted in stroma at day 16. It localized to urothelial nuclei at day 21 and was undetectable at 42 days. Adjacent to the urothelium alpha-smooth muscle actin was seen on day 16 and it was localized in bundles to the periphery of the graft at later time points. Staining for basilar urothelium with p63 confirmed basilar orientation at all time points. CONCLUSIONS: We report the temporal spatial expression of various genes in early bladder development. This suggests that some proteins may be potential markers of bladder progenitor cells. Characterizing these markers may potentially identify bladder progenitor cells that have been directed toward a lineage path destined to become urothelial cells. Ultimately these multipotential progenitor cells could be isolated and used to study and treat diseases that affect the bladder.

Down-regulation of p57Kip2 induces prostate cancer in the mouse.

p57(Kip2) has been considered a candidate tumor suppressor gene because of its location in the genome, biochemical activities, and imprinting status. However, little is known about the role of p57(Kip2) in tumorigenesis and cancer progression. Here, we show that the expression of p57(Kip2) is significantly decreased in human prostate cancer, and the overexpression of p57(Kip2) in prostate cancer cells significantly suppressed cell proliferation and reduced invasive ability. In addition, overexpression of p57(Kip2) in LNCaP cells inhibited tumor formation in nude mice, resulting in well-differentiated squamous tumors rather than adenocarcinoma. Furthermore, the prostates of p57(Kip2) knockout mice developed prostatic intraepithelial neoplasia and adenocarcinoma. Remarkably, this mouse prostate cancer is pathologically identical to human prostate adenocarcinoma. Therefore, these results strongly suggest that p57(Kip2) is an important gene in prostate cancer tumorigenesis, and the p57(Kip2) pathway may be a potential target for prostate cancer prevention and therapy.

Neuroendocrine differentiation in the 12T-10 transgenic prostate mouse model mimics endocrine differentiation of pancreatic beta cells.

BACKGROUND: Neuroendocrine (NE) prostate cancer develops as an aggressive disease that does not respond to androgen ablation therapy. It has been demonstrated that the paracrine action of NE cells facilitates the progression of androgen dependent adenocarcinoma to an androgen independent state, suggesting a significant role for NE cells during failure of androgen ablation therapy. METHODS: To investigate the pathways that are involved in NE differentiation of prostate cancer, we have looked at the expression of genes known to be involved in endocrine differentiation of beta-cells in the pancreas. This study has been performed using the NE prostate cancer mouse model (12T-10) and the derivative allograft model (NE-10). RESULTS: Immunohistochemical studies have shown that the neuroendocrine prostate tumors express the transcription factors Foxa2, mouse achaete-scute homolog-1 (mash-1), neurogenin3 (Ngn3) and Nkx2.2. These tumors show a loss of hairy/enhancer of split (Hes-1), a gene that inhibits NE differentiation. Human NE prostate cancers also express Foxa2 and human achaete-scute homolog-1 (HASH-1). These genes are expressed in NE prostate tumors in the similar sequential manner as they appear in a pancreatic beta-cell endocrine differentiation. Foxa2 expression is detected in early prostatic intraepithelial neoplasia (PIN). Mash-1 expression is detected in a few clusters within low grade PIN lesions and Nkx2.2 expression is rarely detected in individual scattered cells within the PIN lesion. Ngn3 and Nkx2.2 frequently appear in the invasive NE cancer. Subsequent NE metastasis to lung and liver show a distinct gene expression pattern. The lung metastasis expresses Ngn3 but does not express Nkx2.2 whereas liver metastases do not express Ngn3 but express Nkx2.2. CONCLUSIONS: These results suggest that Ngn3 and Nkx2.2 expression are markers for site-specific metastasis and/or transcriptionally regulated genes that are required for organ-specific metastasis. This study indicates that a pathway similar to pancreatic beta-cell differentiation is involved in NE differentiation of prostate cancer.

Urothelial inhibition of transforming growth factor-beta in a bladder tissue recombination model.

PURPOSE: We examined the role of transforming growth factor-beta in urothelial and bladder development. Transforming growth factor-beta signaling was attenuated in the urothelial compartment and the subsequent effects were examined in a tissue recombination model. MATERIALS AND METHODS: Urothelium was cultured from adult rat bladders and transfected with control vector C7Delta or mutant DNIIR (dominant negative transforming growth factor-beta receptor II). Grafts were created by recombining transfected urothelium plus embryonic day 18 bladder mesenchyma and placed beneath the renal capsule of athymic mouse hosts. Grafts were harvested at 21 and 42 days. Final tissues were evaluated with staining and immunohistochemistry using hematoxylin and eosin, Gomori's trichrome strain, broad-spectrum uroplakin, smooth muscle actin-alpha, phosphorylated SMAD2 and Ki67 antigen. Bladder structures were defined as having smooth muscle, suburothelial connective tissue and mature urothelium expressing uroplakin. Urothelial compartment diameters were measured and subcategorized as small--0.10 to 0.40, medium--0.41 to 1.0 and large--greater than 1.1 mm. RESULTS: At 21 days 14 C7Delta control and 15 DNIIR grafts were evaluated. No bladder tissue was seen in the C7Delta grafts vs 49 in DNIIR tissue, including 30 small, 9 medium and 10 large tissues. At 42 days 14 C7Delta and 12 DNIIR grafts were evaluated. Six bladder structures (5 small and 1 medium) were seen in the C7Delta cohort vs 27 (14 small, 7 medium and 6 large) in the DNIIR group. Immunohistochemical detection of phosphorylated-SMAD2 was significantly attenuated in DNIIR tissue. In addition, Ki67 proliferative indexes were 4.0-fold higher in the DNIIR cohort compared to those in C7Delta tissues. CONCLUSIONS: We successfully observed that primary urothelium cultures can be genetically manipulated and recombined with undifferentiated mesenchyma to grow bladder tissue. By attenuating transforming growth factor-beta signaling in the urothelium superior bladder tissue growth occurred, suggesting that transforming growth factor-beta is a growth inhibitor in this organ system.

Wilms' tumorigenesis is altered by misexpression of the transcriptional co-activator, CITED1.

PURPOSE: Wilms' tumors arise from arrested differentiation of renal progenitor cells. CITED1 is a transcriptional regulator that blocks the metanephric mesenchymal-to-epithelial conversion and is expressed in the blastema of both the developing kidney and Wilms' tumors. We hypothesized that alterations of CITED1-dependent signaling promote persistence of blastema and thereby subject these pluripotent cells to future oncogenic events. METHODS: We used a retroviral delivery system to overexpress the full-length CITED1 (F/L) protein and 2 deletion mutants lacking either of its known functional domains, deltaSID (Smad-4 Interacting Domain) and deltaCR2 (Conserved Region 2; the CITED1 transactivation domain), in a human Wilms' tumor cell line that endogenously expresses CITED1. In vitro effects on cellular proliferation and apoptosis were assayed. In vivo effects on tumorigenesis, growth, proliferation, and apoptosis were determined after heterotransplantation into immunodeficient mice (n = 15 per cell line). RESULTS: In vitro, overexpression of CITED1-F/L significantly increased, whereas overexpression of the functionally inactivating mutant, CITED1-deltaCR2, significantly reduced cellular proliferation relative to the other lines (P < .0001). In vivo, Wilms' tumor incidence was significantly reduced in animals injected with cells overexpressing the mutant CITED1-deltaCR2 (7%) compared with CITED1-F/L (40%, P = .03) and CITED1-deltaSID (60%, P < .002). Similarly, mean tumor volume was least in the CITED1-deltaCR2 animals when compared with CITED1-F/L (P = .03) and CITED1-deltaSID animals (P < .005). Furthermore, the CITED1-deltaCR2 tumor showed the least cellular proliferation. Misexpression of CITED1 did not affect apoptosis either in vitro or in vivo. CONCLUSIONS: Overexpression of CITED1 in a human Wilms' tumor cell line significantly increases proliferation in vitro, whereas mutation of its functionally critical transactivation domain (deltaCR2) significantly reduces proliferation. This mutation further perturbs tumorigenesis and tumor growth after heterotransplantation into immunodeficient mice. We speculate that overexpression of CITED1 promotes expansion of a rapidly proliferating population of blastema and thereby induces an unstable environment highly susceptible to future oncogenic events.

Primary extrarenal nephroblastomatosis.

We report an unusual case of primary extrarenal nephroblastomatosis present along the tunica albuginea of a testis found incidentally during routine inguinal orchiopexy. The worldwide published data and embryologic implications of extrarenal nephroblastomatosis and Wilms tumor are discussed.

Directed differentiation of embryonic stem cells into bladder tissue.

Manipulatable models of bladder development which interrogate specific pathways are badly needed. Such models will allow a systematic investigation of the multitude of pathologies which result from developmental defects of the urinary bladder. In the present communication, we describe a model in which mouse embryonic stem (ES) cells are directed to differentiate to form bladder tissue by specific interactions with fetal bladder mesenchyme. This model allows us to visualize the various stages in the differentiation of urothelium from ES cells, including the commitment to an endodermal cell lineage, with the temporal profile characterized by examining the induction of specific endodermal transcription factors (Foxa1 and Foxa2). In addition, final functional urothelial differentiation was characterized by examining uroplakin expression. It is well established that ES cells will spontaneously develop teratomas when grown within immunocompromised mouse hosts. We determined the specific mesenchymal to ES cell ratios necessary to dictate organ-specific differentiation while completely suppressing teratomatous growth. Embryonic mesenchyme is well established as an inductive tissue which dictates organ-specific programming of epithelial tissues. The present study demonstrates that embryonic bladder mesenchyme can also steer ES cells towards developing specific endodermal derived urothelium. These approaches allow us to capture specific stages of stem cell differentiation and to better define stem cell hierarchies.

Androgen-dependent prostate epithelial cell selection by targeting ARR(2)PBneo to the LPB-Tag model of prostate cancer.

Cell cultures representing different stages of prostatic carcinoma will be a useful tool allowing a more complete understanding of the role of individual genes in tumorigenesis. We used the androgen-regulated probasin promoter linked to the neomycin phosphotransferase (Neo) gene, to generate the ARR(2)PBneo transgenic mouse model. Development was normal and all six ARR(2)PBneo transgenic founder lines expressed the Neo gene in a prostate-specific manner. Line C, which expressed high levels of neo, was crossbred to LPB-Tag 12T-7f transgenic mice (in which the SV40 large T antigen (Tag) was targeted to the prostate by the large probasin (LPB) promoter). Three bigenic males (carrying both Neo and Tag transgenes) were identified. Prostatic lesions developed in these mice in a predictable and heritable manner, indicating that Neo did not alter Tag-induced prostate tumor development and progression. Three separate NeoTag epithelial cell strains were established from three bigenic mice. G418 selection was used to obtain immortalized epithelial cells in culture. Selected cells expressed the Neo and Tag transgenes, cytokeratins 8 and 18, and were androgen responsive for growth. To determine if these NeoTag cells maintained a similar in vivo phenotype to the 12T-7f transgenic line, tissue recombinations were made with rat urogenital sinus mesenchyme (rUGM) and grafted under the renal capsule of male nude mouse hosts. In recombinants, the three NeoTag strains developed PIN lesions and/or more extensive adenocarcinoma than seen in the 12T-7f mouse. Androgen ablation demonstrated that the grafts were androgen responsive. NeoTag cells grafted without rUGM developed undifferentiated adenocarcinoma demonstrating that prostatic stroma dictates the glandular architecture seen in the well-differentiated adenocarcinoma.