Cooperation of tissue factor cytoplasmic domain and PAR2 signaling in breast cancer development.

Constitutive expression of tissue factor (TF) by cancer cells triggers local activation of the coagulation cascade and promotes breast cancer progression through cell signaling involving protease activated receptor (PAR)2. In human breast cancer, TF and PAR2 are up-regulated and TF cytoplasmic domain phosphorylation is correlated with relapse. Here we show that cancer cell PAR2 signaling promotes angiogenesis independent of PAR2 phosphorylation at the recognized ß-arrestin recruitment site. Similar to PAR2(-/-) mice, TF cytoplasmic domain-deleted (TF(ΔCT)) mice have delayed spontaneous breast cancer development in the polyoma middle T model. Simultaneous deletion of PAR2 in TF(ΔCT) mice did not further delay tumor appearance, consistent with overlapping roles of TF and PAR2 in promoting the angiogenic switch in early stages of breast cancer. In advanced carcinomas, tumor-associated macrophages were reduced in TF(ΔCT) and TF(ΔCT)/PAR2(-/-) mice, and increased tumor vessel diameters of TF(ΔCT) mice were partially reversed by PAR2-deficiency, indicating that the TF cytoplasmic domain has additional roles that are interdependent with PAR2 signaling in regulating host angiogenic responses. These experiments demonstrate a crosstalk of tumor cell TF cytoplasmic domain and PAR2 signaling and provide a possible mechanism for the close correlation between TF phosphorylation and cancer recurrence of TF and PAR2-positive clinical breast cancer.

Defined conditions for the isolation and expansion of basal prostate progenitor cells of mouse and human origin.

Methods to isolate and culture primary prostate epithelial stem/progenitor cells (PESCs) have proven difficult and ineffective. Here, we present a method to grow and expand both murine and human basal PESCs long term in serum- and feeder-free conditions. The method enriches for adherent mouse basal PESCs with a Lin(-)SCA-1(+)CD49f(+)TROP2(high) phenotype. Progesterone and sodium selenite are additionally required for the growth of human Lin(-)CD49f(+)TROP2(high) PESCs. The gene-expression profiles of expanded basal PESCs show similarities to ESCs, and NF-kB function is critical for epithelial differentiation of sphere-cultured PESCs. When transplanted in combination with urogenital sinus mesenchyme, expanded mouse and human PESCs generate ectopic prostatic tubules, demonstrating their stem cell activity in vivo. This novel method will facilitate the molecular, genomic, and functional characterization of normal and pathologic prostate glands of mouse and human origin.

Expression and prognostic significance of cancer stem cell markers CD24 and CD44 in urothelial bladder cancer xenografts and patients undergoing radical cystectomy.

OBJECTIVES: To evaluate CD24/CD44/CD47 cancer stem cell marker expressions in bladder cancer (BCa) and provide data on their prognostic significance for clinical outcome in patients undergoing radical cystectomy (RC). MATERIAL AND METHODS: Primary BCa tissue was used for xenograft studies. A tissue microarray was prepared using specimens from a cohort of 132 patients. All patients underwent RC for urothelial BCa between 2001 and 2010. Expression of CD24, CD44, and CD47 was examined in primary samples and xenografts by fluorescence-activated cell sorting. Populations of CD24(low)- and CD24(high)-expressing cells were sorted and evaluated for tumorigenicity in vivo. Tissue microarray was analyzed for CD24/CD44 staining intensity and tumor-specific vs. stromal cell staining. Associations with BCa survival, BCa stage, and lymph node status were evaluated by univariate and multivariate analyses. RESULTS: CD24 and CD44/CD47 expressions mark distinct cell populations within the normal urothelium as well as in BCa. CD24(high/low) expression was not sufficient to characterize CD24 as a BCa-initiating marker in in vivo primary xenotransplants. CD24 and CD44 expressions correlated with lower cancer-specific survival in patients. However, multivariate analyses of CD24 or CD44 did not demonstrate significantly increased hazards for cancer-specific death if analyzed together with stage, grade, and nodal status of patients. CONCLUSIONS: Cancer stem cell markers CD24/CD44/CD47 are differentially expressed in cells of urothelial BCa in patients undergoing RC and influence cancer-specific survival of patients. Further evaluation of CD24/CD44/CD47 protein expression could be of high therapeutic value in BCa. However, both CD24 and CD44 expressions cannot be regarded as independent prognostic parameters for patients undergoing RC.

Label retaining cells in cancer--the dormant root of evil?

The phenomenon of cellular dormancy has been observed in normal adult stem cells in many different tissues such as the skin, the intestine and the hematopoietic system. These dormant cells have been proposed to be important for life-long self-renewal and for the generation of the different cellular lineages. As tumor cells can share properties with normal stem cells, dormant cells might also exist within a tumor. The term tumor dormancy has evolved from the clinical observation in cancer patients that relapse can occur years to decades after apparently successful treatment, suggesting that some cancer cells might resist chemotherapy and persist in a dormant state. Several studies investigating the role of cellular dormancy in normal stem cells and in cancer hint towards a complex network involving different pools of cells. These cells might interact with each other or even dynamically switch their phenotypes dependent upon so far unknown endogenous and microenvironmental stimuli. In this review, we will discuss the recent findings related to cellular dormancy in normal adult stem cells and in cancer. Furthermore, the clinical relevance of dormancy and its dynamic regulation in tumor cells will be highlighted.

Identification of a population of blood circulating tumor cells from breast cancer patients that initiates metastasis in a xenograft assay.

It has been hypothesized that carcinoma metastasis is initiated by a subpopulation of circulating tumor cells (CTCs) found in the blood of patients. However, although the presence of CTCs is an indicator of poor prognosis in several carcinoma entities, the existence and phenotype of metastasis-initiating cells (MICs) among CTCs has not been experimentally demonstrated. Here we developed a xenograft assay and used it to show that primary human luminal breast cancer CTCs contain MICs that give rise to bone, lung and liver metastases in mice. These MIC-containing CTC populations expressed EPCAM, CD44, CD47 and MET. In a small cohort of patients with metastases, the number of EPCAM(+)CD44(+)CD47(+)MET(+) CTCs, but not of bulk EPCAM(+) CTCs, correlated with lower overall survival and increased number of metastasic sites. These data describe functional circulating MICs and associated markers, which may aid the design of better tools to diagnose and treat metastatic breast cancer.