Invasive prostate cancer cells are tumor initiating cells that have a stem cell-like genomic signature

Development of metastasis is a leading cause of cancer-induced death. Acquisition of an invasive tumor cell phenotype suggests loss of cell adhesion and basement membrane breakdown during a process termed epithelial-to-mesenchymal transition (EMT). Recently, cancer stem cells (CSC) were discovered to mediate solid tumor initiation and progression. Prostate CSCs are a subpopulation of CD44⁺ cells within the tumor that give rise to differentiated tumor cells and also self-renew. Using both primary and established prostate cancer cell lines, we tested the assumption that CSCs are more invasive. The ability of unsorted cells and CD44-positve and -negative subpopulations to undergo Matrigel invasion and EMT was evaluated, and the gene expression profiles of these cells were analyzed by microarray and a subset confirmed using QRT-PCR. Our data reveal that a subpopulation of CD44⁺ CSC-like cells invade Matrigel through an EMT, while in contrast, CD44⁻ cells are non-invasive. Furthermore, the genomic profile of the invasive cells closely resembles that of CD44⁺CD24⁻ prostate CSCs and shows evidence for increased Hedgehog signaling. Finally, invasive cells from DU145 and primary prostate cancer cells are more tumorigenic in NOD/SCID mice compared with non-invasive cells. Our data strongly suggest that basement membrane invasion, an early and necessary step in metastasis development, is mediated by these potential cancer stem cells. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Stromal Androgen Receptor Roles in the Development of Normal Prostate,Benign Prostate Hyperplasia,and Prostate Cancer

The prostate is an androgen-sensitive organ that needs proper androgen/androgen receptor (AR) signals for normal development. The progression of prostate diseases, including benign prostate hyperplasia (BPH) and prostate cancer (PCa), also needs proper androgen/AR signals. Tissue recombination studies report that stromal, but not epithelial, AR plays more critical roles via the mesenchymal-epithelial interactions to influence the early process of prostate development. However, in BPH and PCa, much more attention has been focused on epithelial AR roles. However, accumulating evidence indicates that stromal AR is also irreplaceable and plays critical roles in prostate disease progression. Herein, we summarize the roles of stromal AR in the development of normal prostate, BPH, and PCa, with evidence from the recent results of in vitro cell line studies, tissue recombination experiments, and AR knockout animal models. Current evidence suggests that stromal AR may play positive roles to promote BPH and PCa progression, and targeting stromal AR selectively with AR degradation enhancer, ASC-J9, may allow development of better therapies with fewer adverse effects to battle BPH and PCa.The prostate contains mainly the stromal cells and epithelial cells that are separated by base members and merged in extracellular matrix. Stromal cells include fibroblasts, smooth muscle cells (SMCs), and other minor inflammatory cells, nerve cells, and endothelial cells.The prostate is developed from the endodermal urogenital sinus¹ that contains an outer layer of embryonic connective tissue urogenital sinus mesenchyme (UGM) and an inner layer of urogenital sinus epithelium (UGE).¹ The initial step of prostate development in UGM involves the differentiation of fibroblasts and SMCs,¹ and in response to the UGM androgen/androgen receptor (AR) signals, UGE can grow into the surrounding stromal cells and develop into the prostate epithelial cells as part of the normal prostate development.The ability of the UGM to induce epithelial development and the developed epithelial cells, in return, to direct UGM to undergo differentiation, suggesting that the reciprocal developmental interactions between UGM and UGE might be governed by androgen/AR signals, which are essential for the development of normal prostate, benign prostate hyperplasia (BPH), and prostate cancer (PCa). Prostate development factors, including its proliferation, differentiation, morphogenesis, and functional maintenance, are all influenced by androgen/AR signals.² Androgen/AR signals also play vital roles in the initiation and progression of BPH and PCa,^3,4 which may require the proper interaction with various AR coregulators.²AR is a member of the nuclear receptor superfamily that can be activated and translocated from cytoplasm to nucleus after binding the testosterone or dihydrotestosterone.^5–7 In prostate, AR is expressed in both epithelial and stromal tissues. The transactivated AR in nucleus may then function through modulation of various downstream target genes to influence the development and maintenance of the prostate. In addition to influencing cell growth directly, epithelial AR and stromal AR can also function through epithelial-mesenchymal transition (EMT) to influence prostate development. EMT is a process by which epithelial cells lose their cell-cell adhesion and gain migratory properties to become mesenchymal-like and/or mesenchymal stem cells. These potent mesenchymal cells may then differentiate into different cell types to influence the progression of BHP⁸ and PCa.⁹This review will focus on the discussion of the roles of stromal AR in the development of normal prostate and prostate diseases.     

Mammary Stem Cells and Breast Cancer—Role of Notch Signalling

Adult stem cells are found in numerous tissues of the body and play a role in tissue development, replacement and repair. Evidence shows that breast stem cells are multipotent and can self renew, which are key characteristics of stem cells, and a single cell enriched with cell surface markers has the ability to grow a fully functional mammary gland in vivo. Many groups have extrapolated the cancer stem cell hypothesis from the haematopoietic system to solid cancers, where using in vitro culture techniques and in vivo transplant models have established evidence of cancer stem cells in colon, pancreas, prostate, brain and breast cancers. In the report we describe the evidence for breast cancer stem cells; studies consistently show that stem cell like and breast cancer initiating populations can be enriched using cell surface makers CD44⁺/CD24⁻ and have upregulated genes which include Notch. Notch signalling has been highlighted as a pathway involved in the development of the breast and is frequently dysregulated in invasive breast cancer. We have investigated the role of Notch in a pre-invasive breast lesion, ductal carcinoma in situ (DCIS), and have found that aberrant activation of Notch signalling is an early event in breast cancer. High expression of Notch 1 intracellular domain (NICD) in DCIS also predicted a reduced time to recurrence 5 years after surgery. Using a non-adherent sphere culture technique we have grown DCIS mammospheres from primary DCIS tissue, where self-renewal capacity, measured by the number of mammosphere initiating cells, were increased from normal breast tissue. A γ-secretase inhibitor, DAPT, which inhibits all four Notch receptors and a Notch 4 neutralising antibody were shown to reduce DCIS mammosphere formation, indicating that Notch signalling and other stem cell self-renewal pathways may represent novel therapeutic targets to prevent recurrence of pre-invasive and invasive breast cancer.     

Syndecan‐1 (CD138) contributes to prostate cancer progression by stabilizing tumour‐initiating cells

Increasing evidence suggests that tumour‐initiating cells (TICs) contribute to the development of prostate cancer. Here, we identified syndecan‐1 as a key molecule maintaining the stability of prostate cancer TICs. Holoclones harbouring the biological properties of stemness were derived from single‐cell cultures of the PC3 human prostate cancer cell line. These holoclones over‐expressed syndecan‐1, but showed reduced expression of NADPH oxidase (NOX) and synthesis of hydrogen peroxide and oxygen radicals. Stable RNA‐mediated silencing of syndecan‐1 gene expression up‐regulated NOX‐dependent generation of reactive oxygen species and reduced the survival of holoclones in vitro. Syndecan‐1 down‐regulation also strongly reduced the number of CD133⁺/CD44⁺ primitive cancer cells and tumour growth in vivo. Interestingly, syndecan‐1 gene knockdown significantly enhanced the tumour‐suppressive effects of docetaxel by inhibiting the docetaxel‐induced increase in CD133⁺/CD44⁺ cells in vivo. In the transgenic adenocarcinoma of the mouse prostate (TRAMP) mouse model of prostate cancer, early intervention with a syndecan‐1 inhibitor (OGT2115) or syndecan‐1 RNAi reduced the incidence of adenocarcinoma and the number of c‐kit⁺/CD44⁺ cells in cancer foci. Finally, we found that syndecan‐1 immunopositivity in prostate cancer cells was significantly associated with biochemical recurrence after radical prostatectomy. Taken together, our results show that syndecan‐1 contributes to prostatic carcinogenesis by maintaining TICs and may be a target molecule for therapy. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

s-SHIP promoter expression marks activated stem cells in developing mouse mammary tissue

Mammary stem cells (MaSCs) play critical roles in normal development and perhaps tumorigenesis of the mammary gland. Using combined cell markers, adult MaSCs have been enriched in a basal cell population, but the exact identity of MaSCs remains unknown. We used the s-SHIP promoter to tag presumptive stem cells with GFP in the embryos of a transgenic mouse model. Here we show, in postnatal mammary gland development, that GFP⁺ cap cells in puberty and basal alveolar bud cells in pregnancy each exhibit self-renewal and regenerative capabilities for all mammary epithelial cells of a new functional mammary gland upon transplantation. Single GFP⁺ cells can regenerate the mammary epithelial network. GFP⁺ mammary epithelial cells are p63⁺, CD24^mod, CD49f^high, and CD29^high; are actively proliferating; and express s-SHIP mRNA. Overall, our results identify the activated MaSC population in vivo at the forefront of rapidly developing terminal end buds (puberty) and alveolar buds (pregnancy) in the mammary gland. In addition, GFP⁺ basal cells are expanded in MMTV-Wnt1 breast tumors but not in ErbB2 tumors. These results enable MaSC in situ identification and isolation via a consistent single parameter using a new mouse model with applications for further analyses of normal and potential cancer stem cells.     

Prostate Stem Cell Compartments : Expression of the Cell Cycle Inhibitor p27Kip1 in Normal, Hyperplastic, and Neoplastic Cells

The stem cells of rapidly renewing tissues give rise to transiently proliferating cells, which in turn give rise to postmitotic terminally differentiated cells. Although the existence of a transiently proliferating compartment has been proposed for the prostate, little molecular anatomical evidence for its presence has been obtained to date. We used down-regulation of the cyclin-dependent kinase inhibitor p27^Kip1 to identify cells capable of entering the proliferative phase of the cell cycle and, therefore, competent to fulfill the role of the transiently proliferating compartment. We examined the expression of p27^Kip1 in relation to its role in the development of prostatic carcinoma. Formalin-fixed paraffin-embedded specimens from matched samples of normal-appearing prostate tissue, benign prostatic hyperplasia, high-grade prostatic intraepithelial neoplasia, primary adenocarcinomas, and pelvic lymph node metastases were evaluated by comparative immunohistochemistry against p27^Kip1. In normal-appearing prostate epithelium, moderate to strong nuclear staining of p27^Kip1 was present in greater than 85% of the terminally differentiated secretory cells. The normal basal cell compartment, believed to contain prostatic stem cells, showed distinctive p27^Kip1 expression; acini in epithelial benign prostatic hyperplasia tissue contained more p27^Kip1-negative basal cells than acini from non-benign prostatic hyperplasia tissue. A third layer of cells was identified that was sandwiched between the basal cells and the luminal cells, and this layer was consistently p27^Kip1 negative. This intermediate layer was accentuated in the periurethral region, as well as in prostate tissue that had been subjected to prior combined androgen blockade. We hypothesize that, on appropriate additional mitogenic stimulation, cells in this layer, and other p27^Kip1-negative basal cells, are competent for rapid entry into the cell cycle. Consistent with the fact that cancer cells are capable of cell division, all cases of high-grade prostatic intraepithelial neoplasia and invasive carcinoma also showed down-regulation of p27^Kip1 as compared with the surrounding normal-appearing secretory cells. In pelvic lymph node metastases, p27^Kip1 expression was also reduced. In summary, our results suggest that lack of nuclear p27^Kip1 protein may delineate a potential transiently proliferating subcompartment within the basal cell compartment of the human prostate. In addition, these studies support the hypothesis that reduced expression of p27^Kip1 removes a block to the cell cycle in human prostate epithelial cells and that dysregulation of p27^Kip1 protein levels may be a critical early event in the development of prostatic neoplasia.     

Helper roles of NK and CD8+ T cells in the induction of tumor immunity

The work in our laboratory addresses two interrelated areas of dendritic cell (DC) biology: (1) the role of DCs as mediators of feedback interactions between NK cells, CD8⁺ and CD4⁺ T cells; and (2) the possibility to use such feedback and the paradigms derived from anti-viral responses, to promote the induction of therapeutic immunity against cancer. We observed that CD8⁺ T cells and NK cells, the classical “effector” cells, also play “helper” roles, regulating ability of DCs to induce type-1 immune immunity, critical for fighting tumors and intracellular pathogens. Our work aims to delineate which pathways of NK and CD8⁺ T cell activation result in their helper activity, and to identify the molecular mechanisms allowing them to induce type-1 polarized DCs (DC1s) with selectively enhanced ability to promote type-1 responses and anti-cancer immunity. The results of these studies allowed us and our colleagues to design phase I/II clinical trials incorporating the paradigms of DC polarization and helper activity of effector cells in cancer immunotherapy.     

Phenotypic characterization of the infiltrating immune cells in normal prostate, benign nodular prostatic hyperplasia and prostatic adenocarcinoma

Background

Immune cell infiltrate is a constant feature in normal prostate, benign nodular prostatic hyperplasia and prostatic adenocarcinoma. This study elaborates on the cells of the immune system present in normal prostate, benign nodular prostatic hyperplasia and prostatic adenocarcinoma.

Hypothesis

Here, we hypothesized that “the development of benign nodular prostatic hyperplasia and prostatic adenocarcinoma is associated with numeric alterations of the immune cell infiltrate”.

Materials and methods

A total of 50 transurethral prostatic resection specimens, each entailing normal prostate, benign nodular prostatic hyperplasia and high grade prostatic adenocarcinoma were evaluated for the density and phenotype of the immune cells using immunohistological methods and mouse monoclonal antibodies decorating T cells (CD3), histiocytes (CD68) and B lymphocytes (CD20).

Results

Immune cell infiltrate was composed of T cells, histiocytes and B-lymphocytes. CD⁺3 T lymphocytes and CD68⁺ cells were the predominant cell populations. We observed variations in the density of the immune cells among the normal prostate, benign nodular prostatic hyperplasia and high grade prostatic adenocarcinoma. Compared with normal prostate, benign nodular prostatic hyperplasia had a statistically significant high density of immune cells (3.4 ± 0.4versus 13.5 ± 1.0, P < 0.00). In contrast, a significant decrease in the counts of these cells was observed in high-grade prostatic adenocarcinoma compared to benign nodular prostatic hyperplasia (13.5 ± 1.0 versus 5.2 ± 0.3, P < 0.01).

Conclusions

The increased density of immune cells (predominantly CD⁺3 T cells) in benign nodular prostatic hyperplasia suggests that the initial response to cellular damage is mediated by cell-mediated immunity. The decreased density of immune cells in high-grade prostatic adenocarcinoma may reflect immunosuppression. The underlying mechanisms of these numeric variations are open for further investigations.     

Human epithelial basal cells are cells of origin of prostate cancer, independent of CD133 status

Normal prostatic epithelium is composed of basal and luminal cells. Prostate cancer can be initiated in both benign basal and luminal stem cells, but because basal cell markers are not expressed in patient tumors, the former result was unexpected. Since the cells of origin of prostate cancer are important therapeutic targets, we sought to provide further proof that basal stem cells have tumorigenic potential. Prostatic basal cells were enriched based on α2β1integrin(hi) expression and further enriched for stem cells using CD133 in nontumorigenic BPH-1 cells. Human embryonic stem cells (hESCs) were also used as a source of normal stem cells. To test their tumorigenicity, we used two alternate stromal-based approaches; (a) recombination with human cancer-associated fibroblasts (CAFs) or (b) recombination with embryonic stroma (urogenital mesenchyme) and treated host mice with testosterone and 17β-estradiol. Enriched α2β1integrin(hi) basal cells from BPH-1 cells resulted in malignant tumor formation using both assays of tumorigenicity. Surprisingly, the tumorigenic potential did not reside in the CD133(+) stem cells but was consistently observed in the CD133(-) population. CAFs also failed to induce prostatic tumors from hESCs. These data confirmed that benign human basal cells include cells of origin of prostate cancer and reinforced their importance as therapeutic targets. In addition, our data suggested that the more proliferative CD133(-) basal cells are more susceptible to tumorigenesis compared to the CD133(+)-enriched stem cells. These findings challenge the current dogma that normal stem cells and cells of origin of cancer are the same cell type(s).     

Characteristics of bone marrow cells under conditions of impaired innervation in patients with spinal trauma

We studied quantitative and functional parameters of bone marrow stem cells and mature lymphocyte population under conditions of impaired innervation in patients with injuries to the cervical and thoracic portions of the spinal cord. Our findings indicated the absence of deficiency of quantitative and proliferative potentials of stem cells and demonstrated intact subpopulation structure of mature lymphocytes and T-cell proliferative activity similar to that in donors. The content of CD34⁺ cells in patients did not differ from that in donors. The percentage of CD34⁺CD38⁻ hemopoietic stem cells was elevated in patients, presumably due to increased proliferative activity of hemopoietic stem cells. The possibility of derivation and in vitro culturing of fibroblast-like cells with mesenchymal stem cell phenotype was demonstrated. __________ Translated from Kletochnye Tekhnologii v Biologii i Meditsine, No. 1, pp. 8–11, January, 2006     

Normal breast stem cells, malignant breast stem cells, and the perinatal origin of breast cancer

Both experimental and epidemiological evidence support the concept that the in utero environment can influence an individual's risk of breast cancer in adult life. Recently identified breast stem cells may be the key to understanding the mechanism underlying this phenomenon. It has been theorized that breast cancers arise from breast stem cells. Our emerging view of the characteristics of normal breast stem cells and their link to malignant breast stem cells is reviewed here. It has also been postulated that factors that expand the normal breast stem cell pool in utero would increase the probability that one such cell might undergo an oncogenic mutation or epigenetic change. We dicuss how a number of proposed perinatal determinants of adult breast cancer risk, including (1) in utero estrogen and IGF-1 levels, (2) birthweight, (3) breast density, and (4) early-life mutagen exposure, can be tied together by this “breast stem cell burden” hypothesis.     

CD133<Superscript>+</Superscript> single cell-derived progenies of colorectal cancer cell line SW480 with different invasive and metastatic potential

Single cell progenies (SCPs) inherit biological properties from their isogenetic mother cells. If a single cancer cell can give rise to progenies, which can be passaged sustainably in vitro and produce tumor in xenotransplantation, the cell should be cancer initiating cell. CD133 (Prominin-1, Prom1) is the marker of human colorectal cancer (CRC) stem cells and probably a marker of metastatic cancer stem cells (CSCs). Thirty-three SCPs of CRC cell line SW480 were isolated by limited dilution methods, thirty of which are CD133 positive and three negative. All of the CD133⁺ SCPs are tumorigenic, and the subcutaneous tumors expanded rapidly, while only 1 of 3 CD133⁻ SCPs developed a minimal tumor in nude mice. Orthotopic transplantation experiments showed that CD133⁺ SCPs possessed heterogeneity in intestinal wall invasion, lymph node and liver metastases. CD133⁺ SCPs varied in cell growth, invasive ability, epithelial-mesenchymal-transition and expression of CSCs markers (CD133, CD44, and CXCR4) associated with metastatic potential. CD133⁻ SCPs did not produce secondary transplanted tumor, intestinal invasion and metastasis. The results indicated CD133⁺ subpopulation of SW480 SCPs bear heterogeneous invasive and metastatic ability, and CRC-CSCs might be a heterogeous subpopulation.     

Isolation and characterization of CD105+/CD90+ subpopulation in breast cancer MDA-MB-231 cell line

Background: The epithelial-mesenchymal transition (EMT) generates cells with properties of stem cells, if that happened, the stem cell should be with mesenchymal property. This study aimed to identify a group of cells with mesenchymal stem cell (MSC)-like characteristics in breast cancer bone metastatic cell line MDA-MB-231, moreover, the relevance between breast cancer stem cells and the EMT was observed. CD105 and CD90, identified as the standards of MSCs, were used for the identification. Methods: The CD105⁺/CD90⁺ and CD105^-/CD90^- subpopulation of MDA-MB-231 cells were detected and sorted by flow cytometry. MSC-like characteristics in cell proliferation, migration and cell cycle were investigated here by MTT asaay, transwell migration assay, and PI staining respectively. The expression profiles of some stem cell-associated genes were also observed by quantitative real time PCR. Results: Around 0.99% and 90.77% of parental cells were identified as CD105⁺/CD90⁺ and CD105^-/CD90^- cell subpopulations respectively. The CD105⁺/CD90⁺ cells exhibited stronger migratory capacity as compared to parental and CD105^-/CD90^- cells, while less CD105⁺/CD90⁺ cells were arrested in the S phase. Besides, pluripotent stem cell factors, like Oct-4, Nanog, Klf4 and Sox-2, were all upregulated in CD105⁺/CD90⁺ cells, with also proliferation increase, as compared with other two populations. Conclusion: The CD105⁺/CD90⁺ subpopulation from breast cancer MDA-MB-231 cells was proven to possess “mesenchymal stem cell-like” characteristics, and its high migratory ability might be associated with EMT. Moreover, using the surface markers of CD105 and CD90 for the identification of MSCs might provide new theoretical basis for the recurrence and metastasis of breast cancer.     

Mice deficient in stem cell antigen‐1 (Sca1, Ly‐6A/E) develop normal primary and memory CD4+ and CD8+ T‐cell responses to virus infection

Stem cell antigen‐1 (Sca1, Ly‐6A/E) is a well‐established marker of murine hematopoietic stem cells, and also is expressed on memory T cells. It has been suggested that the functional maintenance of T‐cell memory requires the expression of Sca1 on a specialized population of memory T cells termed “memory stem cells”. Here, we evaluate the requirement for Sca1 in the primary T‐cell response to virus infection, and in the establishment and maintenance of T‐cell memory. We find that Sca1 expression increases on almost all CD4⁺ and CD8⁺ T cells during virus infection, and remains high on virus‐specific memory cells. However, Sca1‐deficient (Sca1KO) mice generate normal primary T‐cell responses to infection; the kinetics, the immunodominance hierarchy, and the absolute numbers of CD4⁺ and CD8⁺ T cells are essentially indistinguishable from those observed in WT mice. Furthermore, by several criteria, primary and memory T cells in Sca1‐deficient mice are phenotypically and functionally normal. These data indicate that Sca1, although perhaps a useful marker of virus‐specific memory T cells, is not required for the regulation of T‐cell quantity or quality, or for the development of a competent pool of memory cells.     

Novel Nuclear Localization of Fatty Acid Synthase Correlates with Prostate Cancer Aggressiveness

Fatty acid synthase is up-regulated in a variety of cancers, including prostate cancer. Up-regulation of fatty acid synthase not only increases production of fatty acids in tumors but also contributes to the transformed phenotype by conferring growth and survival advantages. In addition, increased fatty acid synthase expression in prostate cancer correlates with poor prognosis, although the mechanism(s) by which this occurs are not completely understood. Because fatty acid synthase is expressed at low levels in normal cells, it is currently a major target for anticancer drug design. Fatty acid synthase is normally found in the cytosol; however, we have discovered that it also localizes to the nucleus in a subset of prostate cancer cells. Analysis of the fatty acid synthase protein sequence indicated the presence of a nuclear localization signal, and subcellular fractionation of LNCaP prostate cancer cells, as well as immunofluorescent confocal microscopy of patient prostate tumor tissue and LNCaPs confirmed nuclear localization of this protein. Finally, immunohistochemical analysis of prostate cancer tissue indicated that nuclear localization of fatty acid synthase correlates with Gleason grade, implicating a potentially novel role in prostate cancer progression. Possible clinical implications include improving the accuracy of prostate biopsies in the diagnosis of low- versus intermediate-risk prostate cancer and the uncovering of novel metabolic pathways for the therapeutic targeting of androgen-independent prostate cancer.Fatty acid synthase (FASN) is a large, multifunctional enzyme that is responsible for the de novo synthesis of long chain fatty acids. Because it is typically unnecessary for FASN to produce fatty acids in cells because of sufficient intake of fatty acids in the diet, FASN is expressed at low levels in most normal tissues. However, FASN expression has been found to be up-regulated in many cancers¹, and in several cancers, including prostate cancer, it correlates with poor prognosis.^2–4 In immortalized human prostate epithelial cells and in the LNCaP human prostate cancer cell line, FASN expression increases cell proliferation and growth in soft agar and results in androgen receptor-dependent formation of invasive adenocarcinoma.⁵ That same study also reported that transgenic expression of FASN in mouse prostate epithelial cells led to prostatic intraepithelial neoplasia and protected against castration- and chemotherapeutic-induced apoptosis, whereas siRNA knockdown of FASN in LNCaP cells resulted in apoptosis.⁵A number of theories have been proposed to explain FASN up-regulation in cancers, which ultimately results in a metabolic shift toward producing large amounts of fatty acids. One such theory is related to the Warburg effect, a phenomenon that is observed in most cancers. This involves an increase in the use of the glycolytic pathway for energy production, which also leads to an increase in the substrates used in de novo fatty acid synthesis.^6,7 It has also been postulated that fatty acid production is necessary to supply the structural components of the cell membrane for actively proliferating tumor cells.⁷ Alternatively, in the hypoxic environment of tumors, FASN may provide a means for balancing redox through its ability to consume reducing molecules such as NADPH.^5–7 Regardless of the exact function(s) of FASN in carcinogenesis, it clearly contributes to the transformed phenotype by conferring growth and survival advantages.Although FASN is an attractive therapeutic target in the treatment of cancer because of its low level of expression in normal tissues and concomitant overexpression in many cancers, small molecule inhibitors designed against this oncogenic protein have experienced limitations in their effectiveness because of poor bioavailability, lack of specificity, and significant side effects.^7–10 To improve on therapeutics to target FASN, it is important to understand the precise mechanisms by which FASN promotes carcinogenesis.The normal location of FASN in the cytoplasm is consistent with its known role in fatty acid synthesis. However, when we were examining immunohistochemical images of FASN expression in prostate cancer specimens, we observed that FASN appeared to be localized to the nucleus in a subset of the tumor cells. Through examination of an online database (The Human Protein Atlas, http://www.proteinatlas.org, last accessed March 15, 2013) that contains patient prostate cancer sections subjected to multiple antibodies raised against FASN, nuclear localization of FASN in a subset of tumor cells was again observed. We sought to confirm the nuclear localization of FASN in prostate cancer and to determine whether it could be used as a clinical marker for this disease. To our knowledge, this is the first observation of FASN localizing to the nucleus in any cell type.     

The Profile of Prostate Epithelial Cytokines and its Impact on Sera Prostate Specific Antigen Levels

The aim of this study was determined the expression of pro inflammatory cytokines in prostate epithelial cells. Furthermore, we analysed the relation between these cytokines and sera PSA levels according the three groups: 0–4, 4–20 and >20 ng/mL. The study was carried out in five normal prostate (NP), 27 benign prostate hyperplastic (BPH) and 18 prostate cancer (PC). Immunohistochemical and Western blot analysis was performed. Serum levels of PSA were assayed by Immulite autoanalyser. The western Blotting analysis revealed an immunoexpression of IL-1α, IL-6 and TNFα in BPH and PC. IL-1α, was absent in NP. Immunohistochemical analysis showed significant high optical density to IL-1α and IL-6 in cancer epithelial cells (19.45 ± 3.25 and 26.2 ± 3.19) compared to normal cells (1.73 ± 1.51 and 4.83 ± 2.65). While, TNFα optical densities were not significant in NP (12.03 ± 2.9), BPH (9.87 ± 3.85) and PC (13.34 ± 2.34). The different profiles of cytokines according sera PSA levels showed a high immunoexpression of the profile (IL-6+, IL-1α+) in BPH patients with PSA between 0–4 and 4–20 ng/mL. However, PC patients with sera PSA between 4 and 20 ng/mL, showed a significant high immunoexpression of the profile (IL-6+, IL-1α−). This data demonstrate a locally production of pro-inflammatory cytokines by prostate epithelial cells and a cross talk between PSA and these cytokines in prostate pathologies.     

Stromal Androgen Receptor in Prostate Development and Cancer

The androgen receptor (AR) in stromal cells contributes significantly to the development and growth of prostate during fetal stages as well as during prostate carcinogenesis and cancer progression. During prostate development, stromal AR induces and promotes epithelial cell growth, as observed from tissue recombinant and mouse knockout studies. During prostate carcinogenesis and progression, the stromal cells begin to lose AR expression as early as at the stage of high-grade prostatic intraepithelial neoplasia. The extent of loss of stromal AR is directly proportional to the degree of differentiation (Gleason grade) and progression of prostate cancer (PCa). Co-culture studies suggested that stromal AR inhibits the growth of malignant epithelial cells, possibly through expression of certain paracrine factors in the presence of androgens. This functional reversal of stromal AR, from growth promotion during fetal prostate development to mediating certain growth-inhibiting effects in cancer, explains to some extent the reason that loss of AR expression in stromal cells may be crucial for development of resistance to androgen ablation therapy for PCa. From a translational perspective, it generates the need to re-examine the current therapeutic options and opens a fundamental new direction for therapeutic interventions, especially in advanced PCa.CME Accreditation Statement: This activity (“ASIP 2014 AJP CME Program in Pathogenesis”) has been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Society for Clinical Pathology (ASCP) and the American Society for Investigative Pathology (ASIP). ASCP is accredited by the ACCME to provide continuing medical education for physicians.The ASCP designates this journal-based CME activity (“ASIP 2014 AJP CME Program in Pathogenesis”) for a maximum of 48 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.CME Disclosures: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose.Prostate cancer (PCa) is the most common non-skin malignancy in the male population within the United States and is the second most common cancer in men worldwide.¹ It is also one of the leading causes of cancer-related deaths in males in the United States.Normal human prostate is composed of an epithelial tissue and an adjacent stroma. The epithelium is composed of two principal cell types, the tall columnar secretory luminal cells that line the glandular ducts and the flattened basal cells surrounding them. In addition, some rare neuroendocrine cells are also present. Often, the terms mesenchyme and stroma are loosely used. Herein, mesenchyme refers to the mesodermal-derived fetal or newborn tissues with instructive induction potential. The word stroma describes the tissues surrounding the prostatic epithelium, later in development. In the adult human prostate, the stroma is composed mainly of smooth muscle cells. However, it also includes some fibroblasts, nerves, blood vessels, and various infiltrating immune and inflammatory cell types.Circulating androgens mediate the development and function of prostate by stimulating the androgen receptor (AR). Rat studies have shown that in stroma, AR is expressed in mesenchymal cells of the urogenital sinus (UGS), especially those adjacent to the epithelium, concurrent with the formation of prostatic buds.^2,3 As the prostate develops and the mesenchymal cells differentiate to form smooth muscle, AR expression is widespread, but not universal, throughout the muscle. In the past, investigators have mainly focused on studying epithelial AR function in prostate. Relatively limited data are available to describe the expression and function of stromal AR in prostate development^2–14 and cancer. Stromal AR is involved in both prostate development and prostate carcinogenesis, with distinct functions in these two processes. We examine the current knowledge and understanding of stromal AR function, including its translational significance.     

Very Small Embryonic/Epiblast-Like Stem Cells: A Missing Link To Support the Germ Line Hypothesis of Cancer Development?

The morphology of several tumors mimics developmentally early tissues, and tumors often express early developmental markers characteristic of the germ line lineage. The presence of these markers in neoplastic cells could reflect the dedifferentiation of somatic cells in which cancer develops or cancer origination in primitive stem cells closely related to the epiblast/germ line. The identification of primitive germ line-derived very small embryonic/epiblast-like stem cells, which are deposited early in embryogenesis in developing organs and persist in several organs into adulthood, raised the possibility that cancer may originate in these cells. In this review, we hypothesize that very small embryonic/epiblast-like stem cells could be a missing link that support the more than 100-year-old concepts of the embryonic rest or germ line origin hypotheses of cancer development; however, further experimental evidence is needed to support this hypothesis.There are several mechanisms leading to cancer development, but it is presently unclear whether cancer originates in differentiated somatic cells or in the stem/progenitor cell compartment. The stem cell origin of cancer hypothesis is based on the assumption that self-renewing stem cells residing in organs and tissues, and not mature differentiated somatic cells such as those lining, for example, the bronchial or stomach mucosa,^1,2 may acquire and accumulate mutations during a lifetime. These mutations are subsequently maintained in stem cell compartments and self-renewing stem cells may be subjected to additional mutations and epigenetic changes such that the genome is destabilized and uncontrolled neoplastic proliferation is initiated. Indeed, recent evidence suggests that malignancy arises from accumulation of mutations and maturation arrest of normal stem/progenitor cells rather than by the dedifferentiation of already differentiated cells.^1,3,4,5,6 Accordingly, normal stem cells may acquire mutations and give rise to cancer stem cells, which are subsequently responsible for tumor growth, tumor regrowth after unsuccessful radio-chemotherapy, and establishing distant metastases.Organ/tissue regeneration and cancer development are likely closely related processes.⁷ Carcinogenesis is very often a response to chronic irritation, inflammation, and tissue damage, potentially developing through misappropriation of homeostatic mechanisms that govern tissue repair and stem cell self-renewal.⁸ Indeed, cancer incidence increases when associated with chronic injury. These observations strongly support a continuous state of repair in the development of cancer, which suggests a role for stem cells in cancer origination.⁹In addition to these hypothetical considerations, recent research from several laboratories has provided direct evidence that several neoplasms (eg, brain tumors, prostate cancer, melanomas, colon and lung cancer) may in fact originate in the stem cell compartment.^1,4,10,11 Accordingly, rare populations of primitive stem cells were identified that are able to give rise to tumors in immunodeficient mice that morphologically resemble those tumors from which they were initially purified.¹²The overall concept that adult tissues contain developmentally primitive cells that can lead to tumors is not novel. During the 19th and early 20th centuries, several investigators proposed that cancer may develop in populations of cells that are left in a dormant state in developing organs during embryogenesis. This so-called “embryonic rest hypothesis of cancer origin” was initially postulated by Recamier (1829), Remak (1854), and Virchow (1858). This theory was later elaborated by Durante (1874) and Cohnheim (1875), who suggested that adult tissues may contain embryonic remnants that normally lie dormant, but that can be “activated” to become cancerous. In agreement with those theories, Wright (1910) proposed a germinal cell origin of Wilm’s tumor (nephroblastoma) and Beard (1911) postulated that tumors arise from displaced and activated trophoblasts or displaced germ cells. The putative cells responsible for those effects, however, were neither clearly identified nor purified from the adult tissues. Furthermore, since the term “stem cell” was not used at that time in scientific language, it is not clear specifically to which type of cells these early pathologists were referring.In this review, we present evidence regarding: 1) the existence of a developmentally primitive population of so-called very small embryonic/epiblast-like stem cells (VSELs) in adult tissues that are deposited in early developing tissues during organogenesis; 2) their relationship to the germ lineage, and 3) some crucial mechanisms that may control/prevent their “unleashed” proliferation. Based on the presence of VSELs in adult tissues, we present our working hypothesis that VSELs could be the missing link that reconciles past theories of the embryonic rest hypothesis of cancer origin with current theories maintaining cancer as a stem cell disorder. The hypothesis presented in this review, however, needs further experimental support and in present form represents a basis for future experimentation. Our goal is to encourage other colleagues to consider the possibility that VSELs could be involved in carcinogenesis.