Although symmetrical and asymmetrical divisions of stem cells have been extensively studied in invertebrate and mammalian neural epithelia, their role remains largely unknown in mammalian non-neural epithelial development, regeneration and tumorigenesis. Here, using basal and luminal cell-specific markers and cell lineage tracing transgenic mice, we report that in developing prostatic epithelia, basal and luminal cells exhibit distinct division modes. While basal cells display both symmetric and asymmetric divisions leading to different cell fates, luminal cells only exhibit symmetrical divisions. Examination of cell division modes in prostate-specific Pten-null mice indicates that both luminal and basal cells can be cellular origins for prostate cancer. Furthermore, analysis of Sox2-expressing cells in p63 and Pten-null mice suggests that basal cells contribute to the luminal population and tumorigenesis. These findings provide direct evidence for the existence of a hierarchy of epithelial cell lineages during prostate development, regeneration and tumorigenesis.

In this study, we report on a novel, highly sensitive IL-10 reporter mouse based on the reporter enzyme β-lactamase and the fluorescence resonance energy transfer substrate coumarin-cephalosporin-fluorescein (4). In contrast to an IL-10 reporter mouse model that we generated by using enhanced GFP as reporter and allowed tracking IL-10 expression only in T cells, the IL-10–β-lactamase reporter (ITIB) mouse enables us to easily analyze and quantify IL-10 production at the single-cell level in all myeloid and lymphoid cell types. Furthermore, the ITIB mouse allows studying of the kinetics of IL-10 expression on a single-cell basis and provides a valuable tool for in vivo screening of cell type-specific IL-10–modulating drugs. Remarkably, the ITIB mouse revealed that, although a significant portion of each myeloid and lymphoid cell type produces IL-10, macrophages represent the major IL-10 producer population in several organs of naive mice. Moreover, using the examples of bacterial infection and transplantable skin melanoma models, we demonstrate the exceptional applicability of the ITIB mouse for the identification of IL-10–producing cells during immune responses in vivo. In this study, we identified tumor-infiltrating F4/80+ macrophages as the major source for IL-10 in B16-F10 melanoma in vivo. During systemic infection with Yersinia enterocolitica, although the proportion of IL-10+ cells increased in each myeloid and lymphoid cell type population, infiltrating CD11b+Ly6G+ neutrophils represent a majority among IL-10–producing cells at the site of infection. We conclude that cells of the innate immune system that are involved in immune homeostasis or immune responses are substantial sources of IL-10.

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Recurrence and metastasis are the main causes of death for prostate cancer patients and cancer stem cells (CSCs) are proposed to play important roles in cancer recurrence and metastasis. It is generally thought that genes upregulated in recurrent/metastatic disease are likely biomarkers of CSCs. Hence we analyzed multiple microarray datasets on prostate tumor tissues to identify upregulated genes associated with cancer recurrence/metastasis, and tried to explore whether those genes were true biomarkers of prostate CSCs. Our results indicated that TOP2A was the most highly upregulated gene in recurrent/metastatic prostate cancer, and its high expression was positively correlated with poor prognosis in patients. Using a promoter reporter system, we unexpectedly discovered enrichment of CSCs in TOP2Aneg cells. Compared to TOP2Ahigh cells, TOP2Aneg cells formed spheres and tumors more efficiently, and became enriched in the presence of stresses. Analysis of cell divisions by time lapse imaging indicated that more slow-cycling cells were observed in TOP2Aneg cells while the proportion of abnormal divisions was higher in TOP2Ahigh cells. Our studies demonstrate that TOP2Ahigh is the phenotype of recurrence/metastasis but TOP2Aneg cells show slow cycling and have CSCs properties in prostate cancer, which has significant implications for prostate cancer therapy.

Interactions of virulent Leptospira interrogans with murine monocyte-macrophage-like J774A.1 cells and Vero (African green monkey kidney fibroblasts) cells from attachment to internalization were investigated by a series of morphological analysis. Fontana silver staining revealed that only the pathogenic leptospires were able to attach to host cells and the attachment pattern varied depending on cell types that they interacted with. Transmission electron microscopy (TEM) analysis confirmed the formation of the leptospires-containing phagosomes and their colocalization with lysosomes in macrophages were verified by confocal microscopic analysis. Results of F-actin rearrangements examination indicated that virulent leptospires invaded host cells via a microfilament-independent pathway.