Biomedical subjects

Xi-De Wang

Publications and source records attributed to Xi-De Wang.

3 recordsLinked to original sources

PubMed2005

Notch signaling is required for normal prostatic epithelial cell proliferation and differentiation.

Notch pathway is crucial for stem/progenitor cell maintenance, growth and differentiation in a variety of tissues. Using a transgenic cell ablation approach, we found in our previous study that cells expressing Notch1 are crucial for prostate early development and re-growth. Here, we further define the role of Notch signaling in regulating prostatic epithelial cell growth and differentiation using biochemical and genetic approaches in ex vivo or in vivo systems. Treatment of developing prostate grown in culture with inhibitors of gamma-secretase/presenilin, which is required for Notch cleavage and activation, caused a robust increase in proliferation of epithelial cells co-expressing cytokeratin 8 and 14, lack of luminal/basal layer segregation and dramatically reduced branching morphogenesis. Using conditional Notch1 gene deletion mouse models, we found that inactivation of Notch1 signaling resulted in profound prostatic alterations, including increased tufting, bridging and enhanced epithelial proliferation. Cells within these lesions co-expressed both luminal and basal cell markers, a feature of prostatic epithelial cells in predifferentiation developmental stages. Microarray analysis revealed that the gene expression in a number of genetic networks was altered following Notch1 gene deletion in prostate. Furthermore, expression of Notch1 and its effector Hey-1 gene in human prostate adenocarcinomas were found significantly down-regulated compared to normal control tissues. Taken together, these data suggest that Notch signaling is critical for normal cell proliferation and differentiation in the prostate, and deregulation of this pathway may facilitate prostatic tumorigenesis.

Amyloid Precursor Protein Secretases↗

PubMed2005

Novel method of generating prostate-specific Cre-LoxP gene switching via intraductal delivery of adenovirus.

BACKGROUND: In order to facilitate elucidation of oncogene or tumor suppressor gene function on initiation and progression of prostate cancer, it would be advantageous to develop an effective method to generate spatially and temporally controlled gene modification in murine prostates. METHODS: Adenovirus expressing Cre-recombinase (Adeno-Cre) was intraductally injected into the prostate of ROSA26 reporter mice. Immmunohistochemical and X-gal staining were performed on prostate tissue sections harvested from mice at various time points following viral injection to confirm expression and activity of Cre-recombinase, respectively. RESULTS: Adenovirus was intraductally delivered to the anterior lobe of the mouse prostate. Using this method of intraductal injection, we were able to precisely obtain Adeno-Cre infection to a majority of epithelial cells but not in the stromal cells or other organs. We further demonstrated that Adeno-Cre infected epithelial cells not only expressed Cre-recombinase enzyme but more importantly, Cre-recombinase activity was revealed through positive X-gal staining in Rosa26 reporter mice, thus, confirming epithelial-specific Cre-loxP recombination in Adeno-Cre infected prostate tissue sections. CONCLUSIONS: This novel method of direct genetic delivery into adult murine prostates could provide an alternative to the more expensive and time-consuming transgenic/knockout approaches. The latter also have other limitations such as the availability of cell-type specific or temporally-regulated promoters, and the complication of genetic background differences, which can potentially be complemented by the technology we describe here.

Adenoviridae↗

PubMed2004

Notch1-expressing cells are indispensable for prostatic branching morphogenesis during development and re-growth following castration and androgen replacement.

Notch expression is frequently associated with progenitor cells, and its function is crucial for development. Our recent work showing that Notch1 is selectively expressed in basal epithelial cells of the prostate and higher Notch1 expression during development suggests that Notch1-expressing cells may define progenitor cells in the prostate. To test this hypothesis, we have generated a transgenic mouse line in which the Notch1-expressing cells can be ablated in a controlled manner. Specific targeting was achieved by expressing the bacterial nitroreductase, an enzyme that catalyzes its substrate into a cytotoxin capable of inducing apoptosis, under the Notch1 promoter. Cell death in transgenic prostate was confirmed by histological analyses including terminal dUTP nick-end labeling and caspase 3 immunocytochemical staining. We evaluated the consequences of ablation of Notch1-expressing cells in two systems, organ culture of early postnatal prostates and re-growth of prostate in castrated mice triggered by hormone replacement. Our data show that elimination of Notch1-expressing cells inhibited the branching morphogenesis, growth, and differentiation of early postnatal prostate in culture and impaired prostate re-growth triggered by hormone replacement in castrated mice. Furthermore, we found that Notch1 expression following castration and hormone replacement was concomitant with known basal cell markers p63 and cytokeratin 14 and was high in the proliferative human prostate epithelial cells. Taken together, these data suggest that Notch1-expressing cells define the progenitor cells in the prostatic epithelial cell lineage, which are indispensable for prostatic development and re-growth.

Androgens↗