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  • Answer added in Stem Cell Biology
    4 Cell Proliferation Assay for non adherent cells
    Brian Wilson · Harvard University
    http://www.dojindo.com/store/c/137-Cell-Proliferation-Cytotoxicity.aspx Dojindo offers an MTT-like kit that does not kill cells so you can measure and... [more]

Publications (20) View all

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    Article: ABCB5 identifies a therapy-refractory tumor cell population in colorectal cancer patients.
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    ABSTRACT: Identification and reversal of treatment resistance mechanisms of clinically refractory tumor cells is critical for successful cancer therapy. Here we show that ATP-binding cassette member B5 (ABCB5) identifies therapy-refractory tumor cells in colorectal cancer patients following fluorouracil (5-FU)-based chemoradiation therapy and provide evidence for a functional role of ABCB5 in colorectal cancer 5-FU resistance. Examination of human colon and colorectal cancer specimens revealed ABCB5 to be expressed only on rare cells within healthy intestinal tissue, whereas clinical colorectal cancers exhibited substantially increased levels of ABCB5 expression. Analysis of successive, patient-matched biopsy specimens obtained prior to and following neoadjuvant 5-FU-based chemoradiation therapy in a series of colorectal cancer patients revealed markedly enhanced abundance of ABCB5-positive tumor cells when residual disease was detected. Consistent with this finding, the ABCB5-expressing tumor cell population was also treatment refractory and exhibited resistance to 5-FU-induced apoptosis in a colorectal cancer xenograft model of 5-FU monotherapy. Mechanistically, short hairpin RNA-mediated ABCB5 knockdown significantly inhibited tumorigenic xenograft growth and sensitized colorectal cancer cells to 5-FU-induced cell killing. Our results identify ABCB5 as a novel molecular marker of therapy-refractory tumor cells in colorectal cancer patients and point to a need for consistent eradication of ABCB5-positive resistant tumor cell populations for more effective colorectal cancer therapy.
    Cancer Research 06/2011; 71(15):5307-16. · 7.86 Impact Factor
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    Article: Genomic convergence among ERRα, PROX1, and BMAL1 in the control of metabolic clock outputs.
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    ABSTRACT: Metabolic homeostasis and circadian rhythms are closely intertwined biological processes. Nuclear receptors, as sensors of hormonal and nutrient status, are actively implicated in maintaining this physiological relationship. Although the orphan nuclear receptor estrogen-related receptor α (ERRα, NR3B1) plays a central role in the control of energy metabolism and its expression is known to be cyclic in the liver, its role in temporal control of metabolic networks is unknown. Here we report that ERRα directly regulates all major components of the molecular clock. ERRα-null mice also display deregulated locomotor activity rhythms and circadian period lengths under free-running conditions, as well as altered circulating diurnal bile acid and lipid profiles. In addition, the ERRα-null mice exhibit time-dependent hypoglycemia and hypoinsulinemia, suggesting a role for ERRα in modulating insulin sensitivity and glucose handling during the 24-hour light/dark cycle. We also provide evidence that the newly identified ERRα corepressor PROX1 is implicated in rhythmic control of metabolic outputs. To help uncover the molecular basis of these phenotypes, we performed genome-wide location analyses of binding events by ERRα, PROX1, and BMAL1, an integral component of the molecular clock. These studies revealed the existence of transcriptional regulatory loops among ERRα, PROX1, and BMAL1, as well as extensive overlaps in their target genes, implicating these three factors in the control of clock and metabolic gene networks in the liver. Genomic convergence of ERRα, PROX1, and BMAL1 transcriptional activity thus identified a novel node in the molecular circuitry controlling the daily timing of metabolic processes.
    PLoS Genetics 06/2011; 7(6):e1002143. · 8.69 Impact Factor
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    Article: Colorectal Cancer Stem Cells: Biology and Therapeutic Implications.
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    ABSTRACT: The hypothesis that cancer is driven by a subpopulation of tumor-initiating or cancer stem cells (CSC), defined by their selective ability for extensive self-renewal and capacity to give rise to nontumorigenic cancer cell progeny through differentiation, has been validated experimentally in diverse human malignancies. Translational relevance of the CSC hypothesis is underlined by emerging novel strategies designed to target all subpopulations within a given tumor in order to effect cancer eradication and improve patient outcomes. Colorectal cancer stem cells (CRSCs) have been identified and successfully isolated by several research groups based on distinct cell-surface marker characteristics. Identification of CRSC populations has led to a wave of discoveries describing novel self-renewal and drug resistance mechanisms in colorectal cancer that represent novel future therapeutic targets. In this review, we will discuss emerging CRSC-specific pathways and the therapeutic promise of targeting this cancer population in colorectal cancer patients.
    Current Colorectal Cancer Reports 06/2011; 7(2):128-135.
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    Article: VEGFR-1 expressed by malignant melanoma-initiating cells is required for tumor growth.
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    ABSTRACT: Melanoma growth is driven by malignant melanoma-initiating cells (MMIC) identified by expression of the ATP-binding cassette (ABC) member ABCB5. ABCB5(+) melanoma subpopulations have been shown to overexpress the vasculogenic differentiation markers CD144 (VE-cadherin) and TIE1 and are associated with CD31(-) vasculogenic mimicry (VM), an established biomarker associated with increased patient mortality. Here we identify a critical role for VEGFR-1 signaling in ABCB5(+) MMIC-dependent VM and tumor growth. Global gene expression analyses, validated by mRNA and protein determinations, revealed preferential expression of VEGFR-1 on ABCB5(+) tumor cells purified from clinical melanomas and established melanoma lines. In vitro, VEGF induced the expression of CD144 in ABCB5(+) subpopulations that constitutively expressed VEGFR-1 but not in ABCB5(-) bulk populations that were predominantly VEGFR-1(-). In vivo, melanoma-specific shRNA-mediated knockdown of VEGFR-1 blocked the development of ABCB5(+) VM morphology and inhibited ABCB5(+) VM-associated production of the secreted melanoma mitogen laminin. Moreover, melanoma-specific VEGFR-1 knockdown markedly inhibited tumor growth (by > 90%). Our results show that VEGFR-1 function in MMIC regulates VM and associated laminin production and show that this function represents one mechanism through which MMICs promote tumor growth.
    Cancer Research 02/2011; 71(4):1474-85. · 7.86 Impact Factor
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    Article: Isolation of tumorigenic circulating melanoma cells.
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    ABSTRACT: Circulating tumor cells (CTC) have been identified in several human malignancies, including malignant melanoma. However, whether melanoma CTC are tumorigenic and cause metastatic progression is currently unknown. Here, we isolate for the first time viable tumorigenic melanoma CTC and demonstrate that this cell population is capable of metastasis formation in human-to-mouse xenotransplantation experiments. The presence of CTC among peripheral blood mononuclear cells (PBMC) of murine recipients of subcutaneous (s.c.) human melanoma xenografts could be detected based on mRNA expression for human GAPDH and/or ATP-binding cassette subfamily B member 5 (ABCB5), a marker of malignant melanoma-initiating cells previously shown to be associated with metastatic disease progression in human patients. ABCB5 expression could also be detected in PBMC preparations from human stage IV melanoma patients but not healthy controls. The detection of melanoma CTC in human-to-mouse s.c. tumor xenotransplantation models correlated significantly with pulmonary metastasis formation. Moreover, prospectively isolated CTC from murine recipients of s.c. melanoma xenografts were capable of primary tumor initiation and caused metastasis formation upon xenotransplantation to secondary murine NOD-scid IL2Rγ(null) recipients. Our results provide initial evidence that melanoma CTC are tumorigenic and demonstrate that CTC are capable of causing metastatic tumor progression. These findings suggest a need for CTC eradication to inhibit metastatic progression and provide a rationale for assessment of therapeutic responses of this tumorigenic cell population to promising emerging melanoma treatment modalities.
    Biochemical and Biophysical Research Communications 10/2010; 402(4):711-7. · 2.48 Impact Factor

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