Studies of murine prostate cancer stem / progenitor cells

UnrestrictedThe application of our prostate epithelium-specific Cre/loxP system to inactivate tumor suppressor genes had resulted in successful development of mouse models of prostate cancer. We further increased the efficiency of the conditional Pten deletion model of prostate adenocarcinoma by combining it with either a conditional luciferase or EGFP reporter line. The growth kinetics of the androgen dependent cancer (AD-Ca) and androgen-depletion independent recurrent cancer (ADI-Ca) could be followed non-invasively in live animals by bioluminescence imaging. We expect that such an investigation will be facilitated by timing the collection of tumorsat specific growth or re-growth points, an advantage that is provided by the model. The EGFP model can provide an opportunity to locate tumors or to isolate enriched populations of cancer cells from tumor tissues via fluorescence-based technologies. Previous studies have shown a small cell subpopulation with Lin-Sca-1+CD49f+ (LSC) cell surface marker phenotypes in the normal murine prostate to have the capacities of stemness. We examined the presence of such cells in our mouse models of prostate cancer, and found a much higher percentage of the LSC cellsubpopulation among the Lin- cells in AD-Ca and ADI-Ca compared to that in the proximal region of the normal counterparts.; To characterize the stemness abilities of cancer LSC cells, we conducted spheroid-forming analyses by the matrigel-based coculture system. Spheroids formed from the cancer LSC cells were larger than those form normal LSC cells. The spheroids could be passaged serially. In the presence of carcinoma associated fibroblasts, they showed a prostate cancer glandular-like structure. We also observed that only cancer LSC cells, not non-LSC, cells formed spheroids. The differentiation to various cell types in spheroids was identified by dual immunofluorescence staining. In the spheroids generated from normal LSC cells, CK8+ luminal cells were located in the intra-lumen layers, and p63+ basal cells in the outer layers. However, in the spheroids formed from cancer LSC cells, most of the cells in the inner layers are p63+CK8+ dual-positive indicating an intermediate phenotype. Taken together, these results describe the opportunity present in the model system to explore the role of stem cells in prostate cancer