Mouse models of prostate cancer: picking the best model for the question.

When the National Institutes of Health Mouse Models of Human Cancer Consortium initiated the Prostate Steering Committee 15 years ago, there were no genetically engineered mouse (GEM) models of prostate cancer (PCa). Today, a PubMed search for "prostate cancer mouse model" yields 3,200 publications and this list continues to grow. The first generation of GEM utilized the newly discovered and characterized probasin promoter driving viral oncogenes such as Simian virus 40 large T antigen to yield the LADY and TRAMP models. As the PCa research field has matured, the second generation of models has incorporated the single and multiple molecular changes observed in human disease, such as loss of PTEN and overexpression of Myc. Application of these models has revealed that mice are particularly resistant to developing invasive PCa, and once they achieve invasive disease, the PCa rarely resembles human disease. Nevertheless, these models and their application have provided vital information on human PCa progression. The aim of this review is to provide a brief primer on mouse and human prostate histology and pathology, provide descriptions of mouse models, as well as attempt to answer the age old question: Which GEM model of PCa is the best for my research question?

The nuclear factor-kappaB pathway controls the progression of prostate cancer to androgen-independent growth.

Typically, the initial response of a prostate cancer patient to androgen ablation therapy is regression of the disease. However, the tumor will progress to an "androgen-independent" stage that results in renewed growth and spread of the cancer. Both nuclear factor-kappaB (NF-kappaB) expression and neuroendocrine differentiation predict poor prognosis, but their precise contribution to prostate cancer progression is unknown. This report shows that secretory proteins from neuroendocrine cells will activate the NF-kappaB pathway in LNCaP cells, resulting in increased levels of active androgen receptor (AR). By blocking NF-kappaB signaling in vitro, AR activation is inhibited. In addition, the continuous activation of NF-kappaB signaling in vivo by the absence of the IkappaBalpha inhibitor prevents regression of the prostate after castration by sustaining high levels of nuclear AR and maintaining differentiated function and continued proliferation of the epithelium. Furthermore, the NF-kappaB pathway was activated in the ARR(2)PB-myc-PAI (Hi-myc) mouse prostate by cross-breeding into a IkappaBalpha(+/-) haploid insufficient line. After castration, the mouse prostate cancer continued to proliferate. These results indicate that activation of NF-kappaB is sufficient to maintain androgen-independent growth of prostate and prostate cancer by regulating AR action. Thus, the NF-kappaB pathway may be a potential target for therapy against androgen-independent prostate cancer.

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.

Prostate epithelial cell fate.

Androgen receptor (AR) within prostatic mesenchymal cells, with the absence of AR in the epithelium, is still sufficient to induce prostate development. AR in the luminal epithelium is required to express the secretory markers associated with differentiation. Nkx3.1 is expressed in the epithelium in early prostatic embryonic development and expression is maintained in the adult. Induction of the mouse prostate gland by the embryonic mesenchymal cells results in the organization of a sparse basal layer below the luminal epithelium with rare neuroendocrine cells that are interdispersed within this basal layer. The human prostate shows similar glandular organization; however, the basal layer is continuous. The strong inductive nature of embryonic prostatic and bladder mesenchymal cells is demonstrated in grafts where embryonic stem (ES) cells are induced to differentiate and organize as a prostate and bladder, respectively. Further, the ES cells can be driven by the correct embryonic mesenchymal cells to form epithelium that differentiates into secretory prostate glands and differentiated bladders that produce uroplakin. This requires the ES cells to mature into endoderm that gives rise to differentiated epithelium. This process is control by transcription factors in both the inductive mesenchymal cells (AR) and the responding epithelium (FoxA1 and Nkx3.1) that allows for organ development and differentiation. In this review, we explore a molecular mechanism where the pattern of transcription factor expression controls cell determination, where the cell is assigned a developmental fate and subsequently cell differentiation, and where the assigned cell now emerges with it's own unique character.

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.

NE-10 neuroendocrine cancer promotes the LNCaP xenograft growth in castrated mice.

Increases in neuroendocrine (NE) cells and their secretory products are closely correlated with tumor progression and androgen-independent prostate cancer. However, the mechanisms by which NE cells influence prostate cancer growth and progression, especially after androgen ablation therapy, are poorly understood. To investigate the role of NE cells on prostate cancer growth, LNCaP xenograft tumors were implanted into nude mice. After the LNCaP tumors were established, the NE mouse prostate allograft (NE-10) was implanted on the opposite flank of these nude mice to test whether NE tumor-derived systemic factors can influence LNCaP growth. Mice bearing LNCaP tumors with or without NE allografts were castrated 2 weeks after NE tumor inoculation, and changes in LNCaP tumor growth rate and gene expression were investigated. After castration, LNCaP tumor growth decreased in mice bearing LNCaP tumors alone, and this was accompanied by a loss of nuclear androgen receptor (AR) localization. In contrast, in castrated mice bearing both LNCaP and NE-10 tumors, LNCaP tumors continued to grow, had increased levels of nuclear AR, and secreted prostate-specific antigen. Therefore, in the absence of testicular androgens, NE secretions were sufficient to maintain LNCaP cell growth and androgen-regulated gene expression in vivo. Furthermore, in vitro experiments showed that NE secretions combined with low levels of androgens activated the AR, an effect that was blocked by the antiandrogen bicalutamide. Because an increase in AR level has been reported to be sufficient to account for hormone refractory prostate cancers, the NE cell population ability to increase AR level/activity can be another mechanism that allows prostate cancer to escape androgen ablation therapy.

Enhanced chemosensitivity of bladder cancer cells to cisplatin by suppression of clusterin in vitro.

We examined the functional role of clusterin in chemotherapy-induced apoptosis and tested whether anti-sense transfection targeted against clusterin enhances the chemosensitivity in human bladder cancer cells in vitro. Clusterin mRNA and protein expression of 253J cells, a human bladder carcinoma cell line, after treatment with cisplatin were measured by RT-PCR and Western blot analysis. Clusterin expression and cell growth were compared between 253J cells transfected with constructed a clusterin anti-sense plasmid vector (pCR-CLU-AS) and controls. Tumor cell viability was measured with MTT assay after cisplatin treatment. DNA fragmentation and CPP32 assay were performed. Clusterin expression was increased after treatment with cisplatin and highest at 8 h in 253J cells. Clusterin anti-sense transfectants were highly sensitive to apoptotic cell death induced by cisplatin compared with parental 253J cells or control transfectants. Collectively, our results showed that expression of clusterin was increased in the acute phase of cell death caused by cisplatin and that suppressing the expression of clusterin enhanced the susceptibility of apoptosis caused by cisplatin in human bladder cancer cells. These results suggest that lowering the expression of clusterin might increase the sensitivity of bladder cancer cells to chemotherapeutic agents.

Suppression of clusterin expression enhanced cisplatin-induced cytotoxicity on renal cell carcinoma cells.

OBJECTIVES: To evaluate whether antisense transfection targeted against clusterin enhances the chemosensitivity in renal cell carcinoma. METHODS: Caki-1, a renal cell carcinoma cell line, and cisplatin were used as chemotherapeutic agents. Clusterin expression of Caki-1 cells after treatment with cisplatin was measured by Western blot analysis. After the construction of a clusterin suppression vector, clusterin expression was compared between Caki-1 cells transfected with the clusterin suppression vector (Caki-1/AS), Caki-1 cells transfected with control vector (Caki-1/VO), and parental Caki-1 cells. Tumor cell viability was measured with the MTT assay at 24 and 48 hours after cisplatin treatment. RESULTS: The expression of clusterin increased gradually in Caki-1 cells, peaking at 24 hours, and was reduced to an almost undetectable level at 48 hours after cisplatin treatment. Clusterin expression was suppressed, and the percentage of viable tumor cells decreased significantly more in the Caki-1/AS than in the Caki-1/VO or parental Caki-1 cells at 24 hours after cisplatin treatment. The change in chemosensitivity of the Caki-1/AS cells lost its significance at 48 hours after cisplatin treatment. CONCLUSIONS: Our results showed that clusterin expression increased transiently after treatment of cisplatin, and its suppression by antisense transfection enhanced the cisplatin-induced cytotoxicity of renal cell carcinoma cells. Clusterin suppression may be a useful modality in enhancing the effects of cytotoxic chemotherapy in renal cell carcinoma.

Alteration of Nitric Oxide Synthase Subtype Expression in Contralateral Testis of Rat in Response to Unilateral Testicular Torsion Followed by Detorsion / 대한비뇨기과학회지

No abstract available.

The Study for Chromosome 3p Loss in Renal Cell Carcinoma by Fluorescence in Situ Hybridization Using Paraffin-Embedded Tissue / 대한비뇨기과학회지

PURPOSE: Conventional pathologic classifications of human renal cell carcinoma give little insight into oncogenesis and little assistance in predicting the clinical behavior of this disease. For genetic classification, deletion of the short arm of chromosome 3(3p), the hallmark of nonpapillary/clear cell RCC, is a major diagnostic criterion. Because of the limited routine applicability of cytogenetics and molecular genetic techniques we investigated fluorescence in situ hybridization(FISH) for the detection of this aberration in RCC. MATERIALS AND METHODS: Isolated nuclei from 8 human RCC paraffin embedded tissue sections were examined with a dual color FISH technique for loss of chromosome 3p. Telomeric DNA probe from 3p and an internal ploidy control probe, centromeric probe of chromosome 2, were applied to the isolated nuclei of RCC. RESULTS: 87.5% of the patients(7) lost chromosome 3p. The loss of 3p in the samples tested was unrelated to patient age, gender, tumor stage, and grade. CONCLUSIONS: FISH for the detection of loss in 3p from paraffin embedded tissue sections provides a sensitive and feasible methods for the genetic classification of kidney tumors and FISH is a very useful diagnostic tool for detection of the genetic aberrations of the tumors.