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Microarray analysis of PC3 prostate tumor-initiating cells (PC3 holoclones)

ABSTRACT: BACKGROUND: Cancer stem-like cells are proposed to sustain solid tumors by virtue of their capacity for self-renewal and differentiation to cells that comprise the bulk of the tumor, and have been identified for a variety of cancers based on characteristic clonal morphologies and patterns of marker gene expression. METHODS: Single cell cloning and spheroid culture studies were used to identify a population of cancer stem-like cells in the androgen-independent human prostate cancer cell line PC3. RESULTS: We demonstrate that, under standard culture conditions, ~10% of PC3 cells form holoclones with cancer stem cell characteristics. These holoclones display high self-renewal capability in spheroid formation assays under low attachment and serum-free culture conditions, retain their holoclone morphology when passaged at high cell density, exhibit moderate drug resistance, and show high tumorigenicity in scid immunodeficient mice. PC3 holoclones readily form spheres, and PC3-derived spheres yield a high percentage of holoclones, further supporting their cancer stem cell-like nature. We identified one gene, FAM65B, whose expression is consistently up regulated in PC3 holoclones compared to paraclones, the major cell morphology in the parental PC3 cell population, and two genes, MFI2 and LEF1, that are consistently down regulated. This molecular profile, FAM65Bhigh/MFI2low/LEF1low, also characterizes spheres generated from parental PC3 cells. The PC3 holoclones did not show significant enriched expression of the putative prostate cancer stem cell markers CD44 and integrin α2β1. PC3 tumors seeded with holoclones showed dramatic down regulation of FAM65B and dramatic up regulation of MFI2 and LEF1, and unexpectedly, a marked increase in tumor vascularity compared to parental PC3 tumors, suggesting a role of cancer stem cells in tumor angiogenesis. CONCLUSIONS: These findings support the proposal that PC3 tumors are sustained by a small number of tumor-initiating cells with stem-like characteristics, including strong self-renewal and pro-angiogenic capability and marked by the expression pattern FAM65Bhigh/MFI2low/LEF1low. These markers may serve as targets for therapies designed to eliminate cancer stem cell populations associated with aggressive, androgen-independent prostate tumors such as PC3. (Mol Cancer. 2010 Dec 29;9:319. doi: 10.1186/1476-4598-9-319; PMID: 21190562; PMCID: PMC3024252).

ORGANISM(S): Homo sapiens

PROVIDER: GSE52161 | GEO | 2013/11/07

SECONDARY ACCESSION(S): PRJNA227068

REPOSITORIES: GEO

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Project description:BACKGROUND: Cancer stem-like cells are proposed to sustain solid tumors by virtue of their capacity for self-renewal and differentiation to cells that comprise the bulk of the tumor, and have been identified for a variety of cancers based on characteristic clonal morphologies and patterns of marker gene expression. METHODS: Single cell cloning and spheroid culture studies were used to identify a population of cancer stem-like cells in the androgen-independent human prostate cancer cell line PC3. RESULTS: We demonstrate that, under standard culture conditions, ~10% of PC3 cells form holoclones with cancer stem cell characteristics. These holoclones display high self-renewal capability in spheroid formation assays under low attachment and serum-free culture conditions, retain their holoclone morphology when passaged at high cell density, exhibit moderate drug resistance, and show high tumorigenicity in scid immunodeficient mice. PC3 holoclones readily form spheres, and PC3-derived spheres yield a high percentage of holoclones, further supporting their cancer stem cell-like nature. We identified one gene, FAM65B, whose expression is consistently up regulated in PC3 holoclones compared to paraclones, the major cell morphology in the parental PC3 cell population, and two genes, MFI2 and LEF1, that are consistently down regulated. This molecular profile, FAM65Bhigh/MFI2low/LEF1low, also characterizes spheres generated from parental PC3 cells. The PC3 holoclones did not show significant enriched expression of the putative prostate cancer stem cell markers CD44 and integrin M-NM-12M-NM-21. PC3 tumors seeded with holoclones showed dramatic down regulation of FAM65B and dramatic up regulation of MFI2 and LEF1, and unexpectedly, a marked increase in tumor vascularity compared to parental PC3 tumors, suggesting a role of cancer stem cells in tumor angiogenesis. CONCLUSIONS: These findings support the proposal that PC3 tumors are sustained by a small number of tumor-initiating cells with stem-like characteristics, including strong self-renewal and pro-angiogenic capability and marked by the expression pattern FAM65Bhigh/MFI2low/LEF1low. These markers may serve as targets for therapies designed to eliminate cancer stem cell populations associated with aggressive, androgen-independent prostate tumors such as PC3. (Mol Cancer. 2010 Dec 29;9:319. doi: 10.1186/1476-4598-9-319; PMID: 21190562; PMCID: PMC3024252). Four PC3 cell-derived holoclones, selected based on their clear and unambiguous holoclone morphology and designated holoclones 2H10, 2G7, 1A8 and 5A2, were used for global transcriptome/microarray analysis in direct comparison to parental PC3 cells. Total RNA was prepared from each of four sequential cell passages for each PC3-derived holoclone, and from four passages of parental PC3 cells, 48 h after seeding the cells at 100,000 cells per well of a 6-well plate. For each sample (holoclones or parental PC3 cells), a pool of RNA was prepared by combining equal amounts of RNA from each passage to minimize the effects of passage number and inter-sample variability on gene expression profiles. All RNAs had an RNA integrity number >8.0, determined using an Agilent Bioanalyzer 2100 instrument. cDNAs transcribed from pools of RNA for each holoclone, and for parental PC3 cells, were labeled with Alexa 647 or Alexa 555 dyes in a fluorescent reverse pair (dye swap) design for competitive hybridization to Agilent Whole Human Genome Microarrays.

Project description:Purpose: To examine the effects of proL1 upregulation on global gene expression in PC3 cells using RNA sequencing (RNA-Seq) Methods: PC3 cells were transformed to overexpress proL1 using lentiviral vectors. The proL1 overexpressing variant (PC3 proL1+) and their parental cell line were plated in 6-well plates in triplicate (3 wells for each cell line). After 3 days, their RNA was isolated using the Qiagen RNeasy Mini kit and their global gene expression patterns were analyzed using RNA-Seq Results: We identified 1698 differentially expressed genes between PC3 proL1+ and its parental cell line. Of these differentially expressed genes (DEGs), 209 were in common with LNCaP when proL1 was overexpressed. To identify biological functions that may be regulated through overexpression of proL1 in LNCaP cells, the list of DEGs was submitted to the DAVID, GOC, and KEGG databases, which identified 1250, 1366, and 480 unique genes within each database, respectively, which were then used for ontological analysis. According to these databases, proL1 overexpression regulated gene expression in ontological groups involved "anatomical structure development/morphogenesis" (more specifically "prostate gland morphogenesis"), extracellular matrix organization," "signaling," and "signal transduction. DEGs were also overrepresented in ontological groups potentially involved in vascularization and blood flow regulation. Analysis of the list of DEGs using the KEGG database identified the ontologic group "pathways in cancer" as having the greatest number of DEGs. DEGs were also identified with significant overrepresentation in specific biochemical pathways, such as the P13K-Akt, VEGF, and MAPK signaling pathways as well as steroid metabolic pathways. However, there were differences in the regulation of specific genes related to the androgen response between LNCaP and PC3. Unlike PC3, where overexpression of ProL1 caused a significant increase in expression of the androgen receptor gene (AR) and a decrease in expression of the estrogen receptor (ESR1), in LNCaP neither of these genes were changed in expression. In contrast, proL1 overexpression in LNCaP reduced expression of the progesterone receptor gene (PGR) but not in PC3 cells. Conclusion: Global analysis of the changes in gene expression caused by proL1 overexpression in PC3 and LNCaP cells supports that it has a role both in the modulation of genetic pathways involved in both overcoming hypoxia and the development of androgen-insensitivity. Opiorphins have previously been shown to be directly involved in regulation of blood-flow to tissues through their modulation of smooth muscle tone, and therefore their upregulation in tumors may directly contribute to overcoming the hypoxic barrier that develops in the growing tumor. In addition, overexpression of ProL1 in both PC3 and LNCaP cells modulated expression of genes involved in angiogenesis and morphogensis; the activation of these pathways would likely be involved in vascularization of the tumor and thereby also contribute to overcoming hypoxia. Overexpression of proL1 also affected genes involved in steroid metabolism and response pathways in both LNCaP and PC3, which could potentially contribute to the modulation of androgen sensitivity. In PC3 proL1+ cells we observed a significant upregulation of the Androgen Receptor (AR). Increased activity of the AR could subsequently lead to the activation of secondary messengers involved in modulating the activity of other signaling pathways such as the PI3K-Akt signaling and MAPK pathways, which had significant over-representation of DEGs in PC3 proL1+ cells. The PI3K-Akt signaling pathway is considered one of the most commonly dysregulated pathways in prostate cancer with approximately 40% of early stage, and 70-100% of advanced staged cancer exhibiting dysregulation of this pathway.

Project description:Cancer stem cells (CSCs) drive prostate cancer (PCa) progression and metastasis. These cells exhibit remarkable self-renewal, chemoresistant and invasive potentials, and are thought to participate in the changes in cellular architecture that lead to epithelial-to-mesenchymal transition (EMT). Conventional therapies fail to eliminate CSCs, which results in tumor recurrence and progression to castration resistant PCa (CRPC). Recent evidence suggests that castration itself can induce EMT, which could potentiate the âstemnessâ and number of CSCs within the tumor. Hence, there is an urgent need for EMT- and CSC-targeted therapies that could prevent progression to CRPC. 22Rv1, DU145, LNCaP, and PC3 cells were grown under sphere-forming conditions standardized in our lab. We have previously demonstrated that these enriched PCa cell lines exhibit phenotypic characteristics associated with CSCs in vivo. Over-expression of the stem-associated CD133 biomarker was determined via flow cytometric analysis. Total RNA was isolated from CD133+ prostasphere-derived cells. Gene expression profiling was carried out using the nCounter NanoString system and three different CodeSets associated with cancer or stem cells. Functional annotation was performed using the over-representation analysis tool from ConsensusPathDB. Functional annotation analysis of upregulated transcripts suggests that prostasphere-derived cells undergo a transcriptional reprogramming that triggers a major phenotypic shift. These changes are similar to the mesenchymal shift associated with EMT that drives PCa progression to CRPC. Each cell line exhibited distinct expression profiles that are presented and analyzed individually. Furthermore, our analysis revealed over-represented pathways that were common to all cell lines, which are related to the MAPK/ERK, PI3K/AKT, Notch, and Wnt stem cell fate signaling networks. Transcriptional analysis of induced CSCs not only offers insight into their underlying pathophysiology, but can also be used as a platform for the discovery of therapeutic targets for CSC-specific intervention. In this contribution, we present a flexible in vitro platform for the identification of functionally relevant therapeutic targets, using cell samples with low numbers of malignant stem/progenitors that were enriched in vitro. This approach represents a novel and effective strategy that can be used in the development of therapeutic strategies, which could ultimately be tailored to the biology of individual patients. 22Rv1, DU145, LNCaP and PC3 prostasphere cultures were sampled on Day 4 (P 2), Day 8 (P 3) and Day 12 (P 4), and compared relative to parental monolayers on Day 0 of culture (P 1). Three independent measurements were carried out for monolayers at Day 0 using the CancerReference Kit. Day 12 prostaspheres were enzymatically dissociated and sorted via MACS using the Anti-CD133/2 (293C3)-PE Antibody (Miltenyi) into CD133+ and CD133- fractions. Total RNA was extracted from CD133+ cells and were analyzed using the nCounter GX Cancer Reference kit, the Stem Cell panel and the custom made ITESM CodeSet (14 genes associated with prostate cancer) from NanoString Technologies. This series contains data for the Stem Cell panel.

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Microarray analysis of PC3 prostate tumor-initiating cells (PC3 holoclones)

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