Predominant expression of fibroblast growth factor (FGF) 8, FGF4, and FGF receptor 1 in nonseminomatous and highly proliferative components of testicular germ cell tumors

Activin and BMP Signalling in Human Testicular Cancer Cell Lines, and a Role for the Nucleocytoplasmic Transport Protein Importin-5 in their Crosstalk

Testicular germ cell tumours (TGCTs) are the most common malignancy in young men. Originating from foetal testicular germ cells that fail to differentiate correctly, TGCTs appear after puberty as germ cell neoplasia in situ cells that transform through unknown mechanisms into distinct seminoma and non-seminoma tumour types. A balance between activin and BMP signalling may influence TGCT emergence and progression, and we investigated this using human cell line models of seminoma (TCam-2) and non-seminoma (NT2/D1). Activin A- and BMP4-regulated transcripts measured at 6 h post-treatment by RNA-sequencing revealed fewer altered transcripts in TCam-2 cells but a greater responsiveness to activin A, while BMP4 altered more transcripts in NT2/D1 cells. Activin significantly elevated transcripts linked to pluripotency, cancer, TGF-β, Notch, p53, and Hippo signalling in both lines, whereas BMP4 altered TGF-β, pluripotency, Hippo and Wnt signalling components. Dose-dependent antagonism of BMP4 signalling by activin A in TCam-2 cells demonstrated signalling crosstalk between these two TGF-β superfamily arms. Levels of the nuclear transport protein, IPO5, implicated in BMP4 and WNT signalling, are highly regulated in the foetal mouse germline. IPO5 knockdown in TCam-2 cells using siRNA blunted BMP4-induced transcript changes, indicating that IPO5 levels could determine TGF-β signalling pathway outcomes in TGCTs.

Zika virus dysregulates human Sertoli cell proteins involved in spermatogenesis with little effect on tight junctions

Zika virus (ZIKV), a neglected tropical disease until its re-emergence in 2007, causes microcephaly in infants and Guillain-Barré syndrome in adults. Its re-emergence and spread to more than 80 countries led the World Health Organization in 2016 to declare a Public Health Emergency. ZIKV is mainly transmitted by mosquitos, but can persist in infected human male semen for prolonged periods and may be sexually transmitted. Testicular Sertoli cells support ZIKV replication and may be a reservoir for persistent ZIKV infection. Electrical impedance analyses indicated ZIKV infection rapidly disrupted Vero cell monolayers but had little effect upon human Sertoli cells (HSerC). We determined ZIKV-induced proteomic changes in HSerC using an aptamer-based multiplexed technique (SOMAscan) targeting >1300 human proteins. ZIKV infection caused differential expression of 299 proteins during three different time points, including 5 days after infection. Dysregulated proteins are involved in different bio-functions, including cell death and survival, cell cycle, maintenance of cellular function, cell signaling, cellular assembly, morphology, movement, molecular transport, and immune response. Many signaling pathways important for maintenance of HSerC function and spermatogenesis were highly dysregulated. These included IL-6, IGF1, EGF, NF-κB, PPAR, ERK/MAPK, and growth hormone signaling. Down-regulation of the PPAR signaling pathway might impact cellular energy supplies. Upstream molecule analysis also indicated microRNAs involved in germ cell development were downregulated by infection. Overall, this study leads to a better understanding of Sertoli cellular mechanisms used by ZIKV during persistent infection and possible ZIKV impacts on spermatogenesis.

Identification of testicular cancer driver genes by a cross-species comparative oncology approach

BACKGROUND

Germ cell tumors arise in the testis, ovary, or extragonadal locations and have a wide range of histopathological and clinical presentations. The relative lack of animal models of germ cell tumors has impeded functional assessment of candidate driver genes. Previously, we described the development of testicular germ cell tumors in zebrafish carrying a mutation in bmpr1bb, a BMP family receptor, and demonstrated that human germ cell tumors have defects in BMP signaling.

OBJECTIVE

To further credential the zebrafish model for studies of human germ cell tumor, and to elucidate conserved genetic programs underlying the development of germ cell tumor.

MATERIALS AND METHODS

We used genetic techniques to ablate the germ cell lineage in developing fish and tested tumors for loss-of-heterozygosity of the wild-type allele of bmpr1bb. We performed comparative gene expression profiling of zebrafish and human germ cell tumors and carried out functional studies of selected genes.

RESULTS

Ablation of germ cells completely prevents testis tumor formation in the fish, definitively establishing the germ cell origin of the tumors. Germ cell tumors in bmpr1bb heterozygous mutants retain the wild-type allele, indicating haploinsufficiency of bmpr1bb as the mechanism of tumor formation. Comparison of RNA-Seq and microarray data from human and zebrafish germ cell tumors revealed a unique overlapping signature shared by the zebrafish tumors with human seminomas, yolk sac tumors, and embryonal carcinomas. The most highly conserved gene set in this cross-species analysis included potential driver genes such as JUP, which we show to be essential for germ cell tumor cell growth.

CONCLUSION

Our findings highlight the value of cross-species comparative oncology for the identification of candidate human cancer genes.

A combination treatment with DNA methyltransferase inhibitors and suramin decreases invasiveness of breast cancer cells

The treatment of patients with invasive breast cancer remains a major issue because of the acquisition of drug resistance to conventional chemotherapy. Here we propose a new therapeutic strategy by combining DNA methyltransferase inhibitors (DMTIs) with suramin. Cytotoxic effects of suramin or combination treatment with DMTIs were determined in highly invasive breast cancer cell lines MDA-MB-231, BT-20 and HCC1954, or control cells. In addition, effects on cell invasion were determined in 3-dimensional cell culture assays. DMTI-mediated upregulation of Protein Kinase D1 (PKD1) expression was shown by Western blotting. Effects of suramin on PKD1 activity was determined in vitro and in cells. The importance of PKD1 in mediating the effects of such combination treatment in cell invasion was demonstrated using 3D cell culture assays. A proof of principal animal experiment was performed showing that PKD1 is critical for breast cancer growth. We show that when used in combination, suramin and DMTIs impair the invasive phenotype of breast cancer cells. We show that PKD1, a kinase that previously has been described as a suppressor of tumor cell invasion, is an interface for both FDA-approved drugs, since the additive effects observed are due to DMTI-mediated re-expression and suramin-induced activation of PKD1. Our data reveal a mechanism of how a combination treatment with non-toxic doses of suramin and DMTIs may be of therapeutic benefit for patients with aggressive, multi-drug resistant breast cancer.

Mutations in LRRC50 predispose zebrafish and humans to seminomas

Seminoma is a subclass of human testicular germ cell tumors (TGCT), the most frequently observed cancer in young men with a rising incidence. Here we describe the identification of a novel gene predisposing specifically to seminoma formation in a vertebrate model organism. Zebrafish carrying a heterozygous nonsense mutation in Leucine-Rich Repeat Containing protein 50 (lrrc50 also called dnaaf1), associated previously with ciliary function, are found to be highly susceptible to the formation of seminomas. Genotyping of these zebrafish tumors shows loss of heterozygosity (LOH) of the wild-type lrrc50 allele in 44.4% of tumor samples, correlating with tumor progression. In humans we identified heterozygous germline LRRC50 mutations in two different pedigrees with a family history of seminomas, resulting in a nonsense Arg488* change and a missense Thr590Met change, which show reduced expression of the wild-type allele in seminomas. Zebrafish in vivo complementation studies indicate the Thr590Met to be a loss-of-function mutation. Moreover, we show that a pathogenic Gln307Glu change is significantly enriched in individuals with seminoma tumors (13% of our cohort). Together, our study introduces an animal model for seminoma and suggests LRRC50 to be a novel tumor suppressor implicated in human seminoma pathogenesis.

The roles of fibroblast growth factors in the testicular development and tumor

Fibroblast growth factors (FGFs) are classically known as hormonal factors and recent studies have revealed that FGFs have a key role in regulating growth and development of several reproductive organs, including the testis. The testis is mainly consisted of germ cells, Sertoli cells and Leydig cells to develop and maintain the male phenotype and reproduction. This review summarizes the structure and fuctions of testis, the roles of FGFs on testicular development and potential involvement in testicular tumor and its regulatory mechanism. Among 23 members of FGFs, the FGF-1, FGF-2, FGF-4, FGF-8, FGF-9, and FGF-21 were involved and describe in details. Understanding the roles and mechanism of FGFs is the foundation to modeling testicular development and treatments in testicular disease. Therefore, in the last part, the potential therapy with FGFs for the testis of cancer and diabetes was also discussed.

Disruption of PCP signaling causes limb morphogenesis and skeletal defects and may underlie Robinow syndrome and brachydactyly type B

Brachydactyly type B (BDB1) and Robinow syndrome (RRS) are two skeletal disorders caused by mutations in ROR2, a co-receptor of Wnt5a. Wnt5a/Ror2 can activate multiple branches of non-canonical Wnt signaling, but it is unclear which branch(es) mediates Wnt5a/Ror2 function in limb skeletal development. Here, we provide evidence implicating the planar cell polarity (PCP) pathway as the downstream component of Wnt5a in the limb. We show that a mutation in the mouse PCP gene Vangl2 causes digit defects resembling the clinical phenotypes in BDB1, including loss of phalanges. Halving the dosage of Wnt5a in Vangl2 mutants enhances the severity and penetrance of the digit defects and causes long bone defects reminiscent of RRS, suggesting that Wnt5a and Vangl2 function in the same pathway and disruption of PCP signaling may underlie both BDB1 and RRS. Consistent with a role for PCP signaling in tissue morphogenesis, mutation of Vangl2 alters the shape and dimensions of early limb buds: the width and thickness are increased, whereas the length is decreased. The digit pre-chondrogenic condensates also become wider, thicker and shorter. Interestingly, altered limb bud dimensions in Vangl2 mutants also affect limb growth by perturbing the signaling network that regulates the balance between Fgf and Bmp signaling. Halving the dosage of Bmp4 partially suppresses the loss of phalanges in Vangl2 mutants, supporting the hypothesis that an aberrant increase in Bmp signaling is the cause of the brachydactyly defect. These findings provide novel insight into the signaling mechanisms of Wnt5a/Ror2 and the pathogenesis in BDB1 and RRS.

Emerging biomarkers in breast cancer care

Currently, decision-making for breast cancer treatment in the clinical setting is mainly based on clinical data, histomorphological features of the tumor tissue and a few cancer biomarkers such as steroid hormone receptor status (estrogen and progesterone receptors) and oncoprotein HER2 status. Although various therapeutic options were introduced into the clinic in recent decades, with the objective of improving surgery, radiotherapy, biochemotherapy and chemotherapy, varying response of individual patients to certain types of therapy and therapy resistance is still a challenge in breast cancer care. Therefore, since breast cancer treatment should be based on individual features of the patient and her tumor, tailored therapy should be an option by integrating cancer biomarkers to define patients at risk and to reliably predict their course of the disease and/or response to cancer therapy. Recently, candidate-marker approaches and genome-wide transcriptomic and epigenetic screening of different breast cancer tissues and bodily fluids resulted in new promising biomarker panels, allowing breast cancer prognosis, prediction of therapy response and monitoring of therapy efficacy. These biomarkers are now subject of validation in prospective clinical trials.

The role of fibroblast growth factors in tumor growth

Biological processes that drive cell growth are exciting targets for cancer therapy. The fibroblast growth factor (FGF) signaling network plays a ubiquitous role in normal cell growth, survival, differentiation, and angiogenesis, but has also been implicated in tumor development. Elucidation of the roles and relationships within the diverse FGF family and of their links to tumor growth and progression will be critical in designing new drug therapies to target FGF receptor (FGFR) pathways. Recent studies have shown that FGF can act synergistically with vascular endothelial growth factor (VEGF) to amplify tumor angiogenesis, highlighting that targeting of both the FGF and VEGF pathways may be more efficient in suppressing tumor growth and angiogenesis than targeting either factor alone. In addition, through inducing tumor cell survival, FGF has the potential to overcome chemotherapy resistance highlighting that chemotherapy may be more effective when used in combination with FGF inhibitor therapy. Furthermore, FGFRs have variable activity in promoting angiogenesis, with the FGFR-1 subgroup being associated with tumor progression and the FGFR-2 subgroup being associated with either early tumor development or decreased tumor progression. This review highlights the growing knowledge of FGFs in tumor cell growth and survival, including an overview of FGF intracellular signaling pathways, the role of FGFs in angiogenesis, patterns of FGF and FGFR expression in various tumor types, and the role of FGFs in tumor progression.

Pleiotropic function of FGF-4: its role in development and stem cells

Fibroblast growth factors (FGFs) were initially recognized as fibroblast-specific growth factor, and it is now apparent that these growth factors regulate multiple biological functions. The diversity of FGFs function is paralleled by the emerging diversity of interactions between FGF ligands and their receptors. FGF-4 is a member of the FGF superfamily and is a mitogen exhibiting strong action on numerous different cell types. It plays a role in various stages of development and morphogenesis, as well as in a variety of biological processes. Recent studies reveal the molecular mechanisms of FGF-4 gene regulation in mammalian cells, which is involved in the developmental process. Furthermore, FGF-4 also acts on the regulation of proliferation and differentiation in embryonic stem cells and tissue stem cells. In this review, we focus on the diverse biological functions of FGF-4 in the developmental process and also discuss its putative roles in stem cell biology.

Cellular signaling by fibroblast growth factors (FGFs) and their receptors (FGFRs) in male reproduction

The major function of the reproductive system is to ensure the survival of the species by passing on hereditary traits from one generation to the next. This is accomplished through the production of gametes and the generation of hormones that function in the maturation and regulation of the reproductive system. It is well established that normal development and function of the male reproductive system is mediated by endocrine and paracrine signaling pathways. Fibroblast growth factors (FGFs), their receptors (FGFRs), and signaling cascades have been implicated in a diverse range of cellular processes including: proliferation, apoptosis, cell survival, chemotaxis, cell adhesion, motility, and differentiation. The maintenance and regulation of correct FGF signaling is evident from human and mouse genetic studies which demonstrate that mutations leading to disruption of FGF signaling cause a variety of developmental disorders including dominant skeletal diseases, infertility, and cancer. Over the course of this review, we will provide evidence for differential expression of FGFs/FGFRs in the testis, male germ cells, the epididymis, the seminal vesicle, and the prostate. We will show that this signaling cascade has an important role in sperm development and maturation. Furthermore, we will demonstrate that FGF/FGFR signaling is essential for normal epididymal function and prostate development. To this end, we will provide evidence for the involvement of the FGF signaling system in the regulation and maintenance of the male reproductive system.

Fator de crescimento fibroblástico básico e seus receptores em relação à atividade proliferativa na placenta bubalina em diferentes fases da gestação

Estudou-se a distribuição espaço-temporal do fator de crescimento fibroblástico básico (bFGF), do receptor 1 do fator de crescimento fibroblástico (FGFR1) e do receptor 2 do fator de crescimento fibroblástico (FGFR2) na placenta bubalina, correlacionando-a à proliferação celular. Para a detecção do bFGF, FGFR1, FGFR2 e antígeno Ki-67, colheram-se 12 placentas de búfalas nos terços inicial, médio e final da gestação, em abatedouros, e realizaram-se testes de imunoistoquímica. Detectou-se e avaliou-se a expressão do bFGF, do FGFR1, do FGFR2 e do antígeno Ki-67 ao longo da gestação. No compartimento fetal da placenta, observaram-se correlações positivas entre a expressão do bFGF e Ki-67, entre FGFR1 e Ki-67 e entre FGFR2 com Ki-67 (r=0,313, 0,358 e 0,384, respectivamente). No epitélio e estroma maternos observaram-se altas correlações entre FGFR1 e Ki-67 (r=0,739 e r=0,511, respectivamente). Os resultados sugerem envolvimento do bFGF, FGFR1 e FGFR2 na proliferação do trofoblasto enquanto no compartimento materno da placenta bubalina apenas o FGFR1 atuaria como modulador dessa atividade.

Oncofetal protein glypican-3 in testicular germ-cell tumor

The expression of an oncofetal protein, the glypican-3 (GPC3), was immunohistochemically evaluated in a wide variety of primary testicular germ-cell tumors (GCTs) in comparison with other markers, alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG)-beta, and OCT3/4. Eighty-nine cases of GCT including 22 cases of mixed GCT were evaluated with reference to each tumor component. GPC3 expression was observed in neoplastic cells of yolk-sac tumor (YST) (25/25), teratoma (2/10), components of syncytiotrophoblastic giant cells (STGCs) (10/14), and choriocarcinoma (1/3), but none in intratubular germ-cell neoplasias, unclassified type (0/33), seminomas (0/61), or embryonal carcinoma (0/19). All cases of YST showed diffuse labeling of neoplastic cells in cytoplasmic and membranous patterns, and the positive area of GPC3 was much larger than that of AFP. Glandular structures in teratomas showed GPC3 immunostaining as well as AFP. Although the number of GPC3-positive cells was smaller in STGC components and choriocarcinoma, there was no diffusion artifact in GPC3 immunostaining, as was frequently encountered in hCG-beta staining. Thus, GPC3 is a unique oncofetal protein, which is useful as an immunohistochemical marker for GCT differentiated to extraembryonic tissue, especially YST.

FGF-4 regulates neural progenitor cell proliferation and neuronal differentiation

The FGF-4 (fibroblast growth factor 4, known as HST-1) protein is an important mitogen for a variety of cell types. However, only limited information is available concerning tissue distribution and the biological role of FGF-4 in the brain. In situ hybridization analysis revealed localization of mouse Fgf-4 mRNA in the normal postnatal mouse hippocampus, subventricular zone (SVZ), and the rostral migratory stream where new neurons generate, migrate, and become incorporated into the functional circuitry of the brain. We also investigated whether FGF-4 could promote both proliferation and differentiation of the neural progenitor cells by using an in vitro neurosphere assay. The addition of recombinant FGF-4 generated large proliferative spheres that have a multipotent differentiation ability. Furthermore, recombinant FGF-4 significantly promotes neuronal differentiation in attached clonal neurosphere culture. These findings suggest that FGF-4 has an ability to promote neural stem cell proliferation and neuronal differentiation in the postnatal brain.

Microinvasive germ cell tumor of the testis

Microinvasive germ cell tumor (MGCT) consists of a limited number of malignant germ cells in the intertubular tissue of the testis. The cells have large nuclei, prominent nucleoli, abundant clear cytoplasm, and distinct cellular borders in hematoxylin and eosin staining. MGCT can be the first stage of malignancy in the development of testicular germ cell tumor (TGCT). Biopsies from men with maldescended testes have been reported to contain intratubular germ cell neoplasia, unclassified (IGCN) and MGCT in 1.8% of the examined cases (95% CI 0.5-4.6%). MGCT has also been found in testes of subfertile men and in the contralateral testis of patients with TGCT. MGCT is a frequent finding (19%) in the testicular tissue adjacent to an overt TGCT. Men with a high risk of TGCT may gain from screening for precursor lesions of TGCT with ultrasonography of the testes followed by a testicular biopsy if suspicious abnormalities are found: Treatment is high-voltage radiotherapy for intratubular germ cell neoplasia (IGCN), and orchidectomy for MGCT and germ cell tumor in situ, either intratubular seminoma or intratubular embryonal carcinoma. After local treatment, patients with precursor lesions can be followed with a surveillance program. The mRNA levels of invasion-related genes were evaluated based on a DNA microarray data set, and we found two gene abnormalities most relevant for the invasion of malignant germ cells: matrix metalloproteinase 9 (MMP9) and plasminogen activator, urokinase (PLAU) genes were up-regulated in a study comparing tissue samples of TGCT and IGCN.

Antisense oligodeoxynucleotide against HST-1/FGF-4 suppresses tumorigenicity of an orthotopic model for human germ cell tumor in nude mice

BACKGROUND

Overexpression of the fibroblast growth factor HST-1/FGF-4 gene is thought to mediate growth properties and malignancy in human testicular germ cell tumors. We have studied the effect that an antisense oligodeoxynucleotide against HST-1/FGF-4 suppresses tumorigenicity of a human germ cell tumor.

METHODS AND RESULTS

To test whether HST-1/FGF-4 could be the target of gene therapy for testicular carcinoma, 20-mer phosphorothioate oligodeoxynucleotides (ODNs) directed against human HST-1/FGF-4 were analyzed for their antitumor activity. The antisense HST-1/FGF-4 ODNs suppressed HST-1/FGF-4 production by NEC8 human nonseminomatous germ cells and inhibited their cell growth in vitro. Furthermore, after orthotopic implantation of NEC8 cells, combined treatment with antisense HST-1/FGF-4 ODNs and Atelocollagen significantly inhibited the growth of testicular tumors as well as the incidence of lymph node metastasis. In contrast, administration of antisense ODNs alone was less effective.

CONCLUSIONS

Collectively, these results indicate that the antisense method against HST-1/FGF-4 gene expression will be a novel therapeutic approach for male germ cell tumors. The use of Atelocollagen-mediated administration of the antisense HST-1/FGF-4 ODNs may be useful in enhancing the effects of antisense therapy.

Chromosomes, genes, and development of testicular germ cell tumors

A literature review found 265 articles on testicular germ cell tumors (TGCTs) detailing the copy number of chromosomal regions and expression of 245 genes. An initial precursor stage, intratubular germ cell neoplasia (IGCN), is characterized by triploidization and an upregulation of KIT, ALPP, CCDN2, and ZNF354A, and a downregulation of CDKN2D. TGCT regularly have a series of chromosomal aberrations: a decrease in copy number at 4q21 approximately qter and 5q14 approximately qter; an increase at 7p21 approximately pter, 7q21 approximately q33, and 8q12 approximately q23 (especially high increase in seminoma); a decrease at 11p11 approximately p15 and 11q14 approximately q24; an increase at 12p11 approximately pter; a decrease at 13q14 approximately q31; an increase of 17q11 approximately q21 (only for nonseminoma); a decrease of 18q12 approximately qter; and an increase at 21q21 approximately qter, 22q11 approximately qter (only for seminoma), and Xq. Macroscopically overt TGCT is associated with a characteristic series of abnormalities in the retinoblastoma pathway including upregulation of cyclin D2 and p27 and downregulation of RB1 and the cyclin-dependent kinase inhibitors p16, p18, p19, and p21. TGCT thus has a synergistic pattern in gene expressions of the retinoblastoma pathway that is rare in other malignancies.

Oct-3/4 is a dose-dependent oncogenic fate determinant

The Oct-3/4 transcription factor sustains embryonic stem (ES) cell self-renewal and is a dose-dependent cell fate determinant. In the adult male, its expression is restricted to type A spermatogonia. We show that Oct-3/4 is expressed in all human testicular germ cell tumors (GCTs) tested, even in the early premalignant component. We demonstrate that Oct-3/4 dictates ES cells' oncogenic potential in a dose-dependent manner; high levels increase the malignant potential of ES cell-derived tumors while Oct-3/4 inactivation induces regression of the malignant component. Oct-3/4 expression in a heterologous cell system transforms nontumorigenic cells and endows tumorigenicity in nude mice. Our findings suggest that Oct-3/4 is not only a distinctive immunohistochemical marker for GCTs, but also plays a critical role in the genesis of these tumors.

Transgenic mouse with high Cre recombinase activity in all prostate lobes, seminal vesicle, and ductus deferens

BACKGROUND

Prostate-specific gene ablation provides a powerful tool for functional characterization of genes that have impact on embryonic development or on other organs, specifically in the prostate. Uniform expression of Cre with high recombinase activity in the prostate is needed for prostate-specific gene ablation based on Cre-loxP recombinations. Currently, available strains of Cre transgenic mice only express Cre recombinase adequately in certain lobes of the prostate. In other lobes, the expression is low and mosaic. Additional strains of transgenic mice expressing high levels of prostate-specific Cre in all prostate lobes would be useful to study the impact of genome manipulation in all prostate lobes.

METHODS

The ARR2PB composite promoter with improved capacity to drive androgen-responsive gene expression was used to initiate expression of a transgene bearing the cDNA encoding a recently modified Cre recombinase with improved recombination activity. In addition, an insulator element from the chicken globin locus that minimized negative effect on transcription of the transgene imposed by chromosome structure was employed. The derived transgenic founders were crossed with the Z/AP reporter mouse and Fgfr2(f/f) mice bearing loxP flanking the FGFR2 locus. Immunochemical and mRNA analyses were employed to test expression and efficacy of the Cre recombinase in the prostate and other tissues.

RESULTS

The ARR2PBi-Cre transgenic mouse specifically and uniformly expressed Cre recombinase in the dorsal, lateral, ventral, and anterior lobes of the prostate, seminal vesicles, and ductus deferens. The Cre recombinase in these tissues effectively excised loxP flanked DNA fragments in the Z/AP reporter that triggered expression of beta-galactosidase, and the loxP-flanked FGFR2(f/f) locus resulting in specific ablation of FGFR2 in the prostate.

CONCLUSIONS

Compared with the currently available prostate-specific Cre strains, the new ARR2PBi-Cre strain exhibited higher and more uniform expression of Cre recombinase in the prostate as well as in seminal vesicles and ductus deferens. This provides an additional tool for efficient hormone-dependent gene targeting in epithelial cells of all lobes of the adult prostate, seminal vesicle, and ductus deferens.

Fibroblast growth factors and their receptors in urological cancers: basic research and clinical implications

Because therapeutical options for advanced urological cancers are limited, the understanding of key elements responsible for invasion and metastasis is very important. It has been hypothesized that progression to malignant growth is associated with a dysregulation of growth factors and/or their receptors. In the last few years, signaling pathways of the fibroblast growth factor (FGF) family have been subject to intense investigation. Fibroblast growth factors constitute one of the largest families of growth and differentiation factors for cells of mesodermal and neuroectodermal origin. The family comprises two prototypic members, acidic FGF (aFGF) and the basic FGF (bFGF), as well as 21 additionally related polypeptide growth factors that have been identified to date. FGFs are involved in many biological processes during embryonic development, wound healing, hematopoesis, and angiogenesis. In prostate, bladder, and renal cancers, FGFs regulate the induction of metalloproteinases (MMP) that degrade extracellular matrix proteins, thus facilitating tumor metastasis. Probably due to their potent angiogenic properties, aFGF and bFGF have received the most attention. However, there is increasing evidence that other FGFs also play crucial roles in tumors of the prostate, bladder, kidney, and testis. This review will discuss the different elements involved in FGF signaling and summarize the present knowledge of their biological and clinical relevance in urological cancers.

Growth regulatory factors and signalling proteins in testicular germ cell tumours

The molecular basis of testicular germ cell tumourigenesis are not well elucidated. Growth factors regulate cell growth, differentiation and apoptosis. Major families of growth factors are present in the male gonad from early fetal development to adult life. They are involved in germ cell proliferation and differentiation. Growth signalling pathways suffer deregulation in many human malignancies. Given the importance of growth signals in normal testicular development and their acquired deregulation in most human cancers, growth factors and signalling molecules that have been implicated in the genesis of testicular germ cell tumours, are reviewed. We detected a somatic mutation of SMAD4 gene, responsible for loss of protein function in seminomas. This mutational inactivation may affect the activity of several members of TGFbeta superfamily (TGFbeta, activin, inhibin, BMP). VEGF expression has been shown to predict metastasis in seminomas. A significant association of HST-1 expression, a member of fibroblast growth factors, with the nonseminomatous phenotype and with tumour stage has been described. In contrast, C-KIT is expressed by seminomas only, from the preinvasive stage. Despite intense expression in almost all seminomas, activating mutation of C-KIT gene is seldom reported. Recently, the first animal model of classical testicular seminoma has been identified in transgenic mouse overexpressing GDNF. RET (GDNF receptor) expression is demonstrated in human seminomas, and not in nonseminomatous tumours. However, the exact molecular alterations of GDNF/RET/GFRalpha1 complex in germ cell tumours are not known. Finally, beside growth factors, other signalling molecules such as peptide hormones may be involved in testicular carcinogenesis. We have demonstrated a specific pattern of somatostatin receptors expression in each type of testicular germ cell tumours, with a loss of sst3 and sst4 in seminomas and loss of sst4 and expression of sst1 in nonseminomas only. These data suggest an antiproliferative action of somatostatin in testicular cancers. In summary, many growth factors and signalling molecules seem to represent specific markers for different histological types of germ cell tumours (seminomas versus nonseminomas) and may play a role in the differentiation of germ cell tumours. Despite a complex signalling pathway involved in the physiological functions of male gonad, little is known about the implication of this signalling network in testicular malignancies. From a practical stand-point, further studies on the role of growth factors in human germ cell tumours may offer a new therapeutical perspective with the development of specific pharmacological signalling modulators that could be used as therapeutic agents.