bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 976: Hypoxic microenvironment promotes breast cancer stem cells through regulation of Polycomb protein expression
Authors: Chang Chun-Ju , Hung Mien-Chie 
Published: June 2012

Abstract
The microenvironment of solid tumors contains regions of poor oxygenation as a result of hypoxia, which is associated with high grade breast cancer and poor prognosis. However, critical regulatory mechanism linking tumor microenvironment to cancer progression remains unclear. Cancer stem cells (tumor initiating cells) are suggested to be responsible for initiation and aggressive progression of cancer. It is recently proposed that an aggressive secondary cancer stem cell population arises from a primary cancer stem cell population through acquisition of additional genomic/genetic mutations and drives cancer progression. Additionally, high expression of a Polycomb protein EZH2, essential in stem cell self-renewal, has been linked to aggressive progression of breast cancer. Here, we discovered that hypoxic microenvironment upregulates HIF1α-mediated transcriptional activation of EZH2 in CD44+CD24−/low breast tumor initiating cells (BTICs) isolated from several human primary tumor samples. Enhanced EZH2 expression was required for the hypoxia-promoted BTICs, where hypoxia significantly increased BTIC abundance, tumor sphere formation and tumor growth in mammary fat pads implanted with less than 500 primary BTICs. Using cDNA expression array and genome wide SNP array analysis, we further identified a novel mechanism in which enhanced expression of EZH2 by hypoxia downregulates DNA damage repair proteins through H3K27 methylation and thereby allows the acquisition of recurrent genomic abnormalities such as RAF1 gene amplification in BTICs. Using proteomic analysis, we demonstrated that RAF1 amplification highly activates its downstream ERK-β-catenin signaling, which leads to enhanced survival and proliferation of the BTICs. Furthermore, using immunohistochemistry analysis in a cohort of breast tumor samples, we found that EZH2 expression is positively correlated with RAF1, p-ERK and β-catenin expression in the high grade, poorly-differentiated tumors but not in the low grade, well-differentiated tumors, suggesting EZH2-amplified RAF1-ERK-β-catenin signaling may contribute significantly to promote BTICs and aggravate breast cancer malignancy. Our data also reveal that AZD6244, a clinical trial drug that inhibits RAF1-ERK signaling, can significantly suppress EZH2-promoted BTICs. To the best of our knowledge, this is the first study that provides evidences linking a specific genomic aberration mediated by EZH2-impaired DNA damage response to expansion of BTICs. Together, this study elucidates a previously unidentified therapeutic effect of RAF1-ERK signaling inhibitors to prevent breast cancer progression by eliminating BTICs.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 976. doi:10.1158/1538-7445.AM2011-976
Abstract 985: Mitochondrial glutamine fermentation enhances ATP synthesis in murine glioblastoma cells
Authors: Seyfried Thomas N. 
Published: June 2012

Abstract
Otto Warburg first proposed that all cancer cells arise from irreversible impairment of respiration, thus requiring glucose fermentation as a compensatory energy source for maintaining viability. Glucose fermentation with lactate production in the presence of oxygen (aerobic glucose fermentation or the Warburg effect) is now recognized as a metabolic hallmark of nearly all cancers. Besides glucose, glutamine also serves as an energy metabolite for many cancer cells. It is not clear, however, how glutamine provides energy to cancer cells. We examined the influence of glucose and glutamine on ATP synthesis and viability in cultured mouse VM-M3 cells, a model for invasive human glioblastoma. The VM-M3 cells are known to have abnormal respiration. The cells were grown for 12 hrs or 24 hrs in “serum free minimal media” containing glucose alone (25 mM), glutamine alone (4.0 mM), or a combination of both energy metabolites. Using a bioluminescent-based in vitro ATP assay, we found that ATP production and cell viability was similar in VM-M3 cells grown in media containing either glutamine or glucose alone. Lactate production was significantly lower in VM-M3 cells grown in glutamine (0.24 mM) than in the cells grown in glucose (2.34 mM), indicating that these cells produce little lactate from glutamine alone. Robust synergy was found for ATP synthesis and lactate production when the cells were grown in both glucose and glutamine. Remarkably, the synergy persisted under anoxia (95% N2, 5% CO2) indicating that OxPhos did not play a major role in the synergistic interaction of glucose and glutamine. Preliminary [C13] NMR analysis showed that the cells grown in pan-labeled glutamine produced labeled succinate, aspartate, alanine, and citrate indicating that glutamine was metabolized through the TCA cycle in these cells. We propose that the glucose/glutamine energy synergy observed in the VM-M3 cells arises from linked fermentation redox couples in the cytoplasm and mitochondria that synthesize ATP largely through non-oxidative substrate level phosphorylations and possibly from an anaerobic electron transfer-based ATP synthesis at the level of fumarate reductase. In other words, the cells appear to generate ATP through simultaneous anaerobic glucose and amino acid fermentation even in the presence of oxygen. Our results support the Warburg cancer theory and suggest that besides glucose fermentation in the cytoplasm, glutamine fermentation in the mitochondria might also serve as an alternative compensatory energy source to OxPhos deficiency. Supported by Boston College Res. Fund.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 985. doi:10.1158/1538-7445.AM2011-985
Abstract 988: Upregulation of pyruvate dehydrogenase kinase 3 mediates hypoxia-induced drug resistance in colon cancer
Authors: Lu Chun-Wun , Lin Shao-Chieh , Chien Chun-Wei , Lin Shih-Chieh , Lin Bo-Wen , Lee Jenq-Chang , Tsai Shaw-Jenq 
Published: June 2012

Abstract
Colorectal cancer is the second leading cause of cancer-related death in both male and female worldwide. Despite the efforts of screening and advances in treatment, 50% of patients with colon cancer will ultimately die from their disease. One major hurdle of treating colon cancer is its high recurrence due to resistance to anti-cancer therapy of hypoxic tumor, a survival advantage resulting from metabolic switch of cancer cells. The switch of cellular metabolism from mitochondrial respiration to glycolysis is the hallmark of cancer cells and is associated with tumor malignancy. Previous studies demonstrated that pyruvate dehydrogenase kinase-1 (PDK1) and PDK3 play an important role in the metabolic switch of cancer cells. Herein, we assessed the expression profile of PDK1 and PDK3 in colorectal cancer. Western blotting results demonstrated that levels of PDK3 were markedly upregulated in colon cancer compared to adjacent normal tissues while levels of PDK1 were decreased in cancer cells. Immunohistochemical staining (n=307) further revealed that expression of PDK3 was positively correlated with the level of hypoxia inducible factor-1α (HIF-1α) and the severity of cancer. Level of PDK3 was markedly induced by hypoxia in a HIF-1α dependent manner, while HIF-2α had no effect on PDK3 expression in colon cancer cell lines. Aberrant expression of PDK3 mediates hypoxia-induced drug resistance as knocking-down PDK3 by siRNA under hypoxia abolished such protective effect. Taken together, these data demonstrated that PDK3 is overexpressed in colon cancer and is associated with tumor malignancy. Our current findings provide novel insights about metabolic switch in cancer cells and suggest that PDK3 can be a new and pivotal target for cancer therapy.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 988. doi:10.1158/1538-7445.AM2011-988
Abstract 990: Metabolic shift in cancer by re-programming of mitochondrial machinery: Novel insight into Warburg-dependent mechanism
Authors: Narain Niven R. , Sarangarajan Rangaprasad , McCook John P. , Jimenez Joaquin J. 
Published: June 2012

Abstract
Otto Warburg described his seminal observation that cancer cells negotiated a switch towards anaerobic respiration from oxidative phosphorylation in return for sustained growth and evasion of normal cellular processes such as cell cycle control and apoptosis. The underlying mechanism that governs this phenomenon has yet to be firmly established. Given the centrality of mitochondria to apoptosis and bioenergetics, we proposed experiments that employed ubidecarenone as an intracellular energy ambassador wherein high-throughput genomic, metabolomic, and proteomic analyses were employed to capture the energetic and molecular signature of cancer cells. Analyses were performed on oncogenic breast, prostate, liver, pancreatic, skin (melanoma, squamous cell carcinoma) and were compared to normal fibroblasts, keratinocytes, hepatocytes, kidney, adipocytes, and human aortic and endothelial cells. The results suggested a hallmark discovery that clearly delineated a differential effect of cancer vs. normal cells under hyperglycemic, hypoxic, and lactate-stressed conditions. A decreased activation of the Pentose Phosphate Shunt was significantly downregulated in cancer cells suggestive of a shift towards utilization of oxygen and glycolysis while Bcl-2 dependent cell death mechanisms were restored. Most notably, cross-talk mechanisms related to p53 and Vegf in the cancer cells and tumor markers and pathology in animal models of melanoma and pancreatic cancer demonstrated efficacy in a topical and intravenous form of Cytotech Labs API 31510, a ubidecarenone based technology that targets the Bcl-2 protein family downstream of a cellular metabolic shift. Conversely, normal cells did not exhibit the aforementioned characteristic indicative of a cancer-specific mechanism. We propose a novel underlying mechanism for the Warburg Hypothesis and demonstrate that pre-clinical work on API 31510 in cancer suggest that it may be a viable agent for control of cancer metabolism and serve as safe, effective anti-cancer agent.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 990. doi:10.1158/1538-7445.AM2011-990
Abstract 994: Monitoring glucose, glutamine and fatty acid metabolism to determine metabolic vulnerability of tumor cells in vitro
Authors: Pike Lisa , Smift Amy , Ferrick David , Wu Min 
Published: June 2012

Abstract
Tumor cells display a metabolism that is strikingly different from that of the normal tissue from which they originated. This metabolic alteration results from activation of oncogenes and/or loss of tumor suppressor genes controlling cellular metabolic pathways as well as adaptation to their microenvironments and provides energy and cellular building blocks, allowing tumor cells to proliferate and survive. The altered metabolism of glucose and glutamine are becoming one of the hallmarks of tumor cells. We present a method that enables rapid assessment of the ability of tumor cells to catabolize the three major nutrient substrates, glucose, glutamine and fatty acids in a microplate using the XF Extracellular Flux Analyzer. Cellular oxygen consumption rate is used as an indicator of substrate oxidation by the mitochondrial respiratory chain upon substrate addition and extracellular acidification rate upon glucose addition is used as an indicator of glycolysis. Furthermore, the maximal capacity of glycolysis and of mitochondrial substrate oxidation is determined by forcing one of the two energy-producing pathways to operate at maximum. In addition, pharmacological inhibition of distinct metabolic pathways allows us to discern the biochemical pathways used, i.e., whether glutamine is metabolized through aminotransferase or glutamate dehydrogenase. Using this approach, we have demonstrated that the nutrient levels in culture medium can markedly shift the ability of cancer cells to use glucose for glycolysis versus oxidation of glutamine and fatty acids and is accompanied by modulation of cell proliferation rate. For example, excessive nutrients induced activation of fatty acid oxidation and enhanced glutamine oxidation in myc-expressing SF188 glioblastoma cells. This shift in substrate use also sensitized these cells to inhibition of fatty acid oxidation. We observed a concomitant increase in the maximal capacity of the mitochondrial respiratory chain with elevated substrate oxidation. In contrast, the apparent glycolysis rate of SF188 cells was much reduced but the glycolytic capacity was retained, which implies these cells have the flexibility to channel glucose to either energy or building block production required for cell mass duplication. We suggest that this type of dynamic analysis provides a rapid means to determine the ability of various types of tumor cells to use glucose, glutamine and fatty acids as well as the maximal capacity of the machineries of glycolysis and substrate oxidation, which may be indicative of metabolic vulnerability and therefore targets of intervention of a particular tumor cell type.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 994. doi:10.1158/1538-7445.AM2011-994
Abstract LB-102: Inhibiting the expansion of hepatic cancer stem cells by targeting β-catenin/CBP interaction with ICG-001 in liver Pten deficient mice
Authors: Stiles Bangyan L. , Galicia Vivian , He Lina , Kahn Michael 
Published: June 2012

Abstract
We used a liver specific Pten (phosphatase and tensin homologue deleted on chromosome ten) deletion murine model to investigate the mechanism of hepatic cancer stem cell activation in vivo. We have shown that loss of PTEN induces the transformation of liver progenitor cells to tumor initiating cells (TICs). Activation of TIC in this model involves death of hepatocytes resulting from PTEN loss induced liver steatosis. Such hepatocytes death presents a selection pressure and altered the progenitor cell niche for mutant progenitor cells to proliferate and replace liver parenchyma. We found that hepatic injury is followed by expansion of hepatic progenitors and upregulation of hepatic progenitor cell markers. In addition, we also found factors governing the progenitor niche such as Wnt ligands including Wnt5a, 7a and 10a as well as Wnt signaling receptor Fzd are induced. Furthermore, β-catenin activation is observed in vivo as well as in progenitor cells isolated from these mice. Thus, we hypothesize that activation of Wnt serves as the niche signal to allow proliferation of mutant progenitors. To test this hypothesis, we treated the isolated progenitor cells with a small molecule compound ICG-001 to interrupt b-catenin/CBP binding. β-catenin/CBP signal allows the activation of progenitor niche by inducing selfrenewal signals while inhibiting differentiation signals. We showed that ICG-001 treatment blocked the self-renewal signals and proliferation of the isolated progenitors in vitro. The in vivo experiment is ongoing and will also be presented at the meeting. Our study demonstrated that β-catenin activation, either directly through PTEN loss or indirectly through PTEN loss induced lipotoxic death of hepatocytes, serves as an important mediator for the activation of Pten mutant progenitor cells. Targeting such niche with our inhibitor may prove to be a viable approach to inhibit liver tumorigenesis.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-102. doi:10.1158/1538-7445.AM2011-LB-102
Abstract LB-105: Identifying molecular markers associated with chemo-resistance in ovarian cancer stem cells
Authors: Dyall Sheetal , Lawrenson Kate , Dafou Dimitra , Gayther Simon A. 
Published: June 2012

Abstract
Stem-like cancer cells, or cancer stem cells (CSC) have been proposed to sustain the growth of tumour cells and give rise to drug resistance in cancer. Side populations (SP) of cells, characterised by their differential ability to efflux Hoechst 33342 from their cytoplasm via multi-drug transporters, are also thought to be enriched in CSCs. The aim of this study was to identify SPs of cancer cells in epithelial ovarian cancer (EOC), and genes within SP populations that both characterize SP cell in EOC cell lines and play a role in the development of resistance to chemotherapeutic agents.
Using flow cytometry, we isolated SP cells from a panel of EOC cell lines. Detectable levels of viable SP cells were observed in the cell lines IGROV1 (1.8–5%), OVCAR3 (0.8%), OVCAR8 (0.2%), and the matched pairs of cisplatin-sensitive cell lines and their resistant variants OV2008 (2.5%)/C13*(1.5%) and A2780 (0.2%)/A2780CP (0.2%). In vitro characterization of SP cells from IGROV1, OVCAR3 and OVCAR8, compared to the non-SP cells showed that SP cells have higher colony forming efficiency when cultured as three-dimensional spheroids in non-adherent culture conditions. A proportion of single SP cells also had the ability to form multi-cellular spheroids in culture (a stem-cell ‘like’ feature) while non-SP cells did not. Under adherent culture conditions, SP cells show a range of morphologies, consisting of holoclones (which are enriched in SP cells) and paraclones (depleted of SP cells). Sub-cloning of holoclones generated both holoclones and paraclones; culturing paraclones led to the formation of only a few paraclones, which senesced. Differential whole-genome gene expression microarray profiling of SP vs non-SP cells identified the P-glycoprotein ABCB1 as the most highly upregulated gene in SP cells, consistent with other studies. Profiling of A2780 and its chemo-resistant derivative A2780CP identified Lin28, an embryonic stem cell marker, as the most differentially over-expressed gene in A2780CP SP cells. SiRNAs to ABCB1 were used to test the hypothesis that knockdown of this marker reduce proportionally the stem cell population in the IGROV1 EOC cell line; siRNAs to Lin28 were used to test whether knockdown of this gene re-sensitized A2780CP cells to cisplatin. Ongoing studies are evaluating the effects on chemosensitivity in vivo, by knocking down Lin28 in A2780CP cells expressing a luciferase reporter. Using Xenogen live animal imaging technologies, tumor burden is being evaluated in real-time, comparing Lin28 knockdown xenografted cell lines with non-silencing siRNA controls.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-105. doi:10.1158/1538-7445.AM2011-LB-105
Abstract LB-108: Formation and maintenance of mesenchymal and stem-cell states in the breast by paracrine and autocrine signals
Authors: Scheel Christina , NgEaton Elinor , Li Sophia Hsin-Jung , Chaffer Christine L. , Reinhardt Ferenc , Kah Kong-Jie , Bell George , Guo Wenjun , Rubin Jeffrey , Richardson Andrea , Weinberg Robert A. 
Published: June 2012

Abstract
Passage through an epithelial-mesenchymal transition (EMT) is associated with the acquisition of migratory and self-renewal abilities in human mammary epithelial cells (MECs). The signaling mechanisms that induce and then maintain these properties have remained unclear. We describe three signaling pathways, involving Transforming Growth Factor (TGF)-beta as well as canonical and non-canonical Wnt signaling, that collaborate to induce epithelial MECs to enter into a mesenchymal and SC-like state. Acting as autocrine signaling loops, these pathways then maintain migratory and self-renewal abilities in normal MECs and control tumorigenicity and metastasis in their transformed derivatives. Autocrine signaling is enabled, at least in part, through downregulation of secreted Wnt antagonists and Bone Morphogenetic Proteins. Like immortalized and transformed MECs, the maintenance of migratory and self-renewal abilities in primary human MECs is dependent on these autocrine loops, suggesting that similar mechanisms regulate biological properties of normal tissue stem cells and tumor-initiating cells in the breast
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-108. doi:10.1158/1538-7445.AM2011-LB-108
Abstract LB-109: BCR-ABL1 kinase activity but not its expression is dispensable for Ph+ quiescent stem cell survival which depends on the PP2A-controlled Jak2 activation and is sensitive to FTY720 treatment
Authors: Neviani Paolo , Harb Jason , Oaks Joshua , Walker Christopher , Santhanam Ramasamy , Paisie Carolyn , Eiring Anna , Zhang Bin , Perazzona Bastianella , Ma Y , Mao Charlene , Marcucci Guido , Holyoake Tessa , Volinia Stefano , Cortes Jorge , Caligiuri Michael , Huettner Claudia , Bittman Robert , Chen Ching-Shih , Arlinghaus Ralph , Hokland Peter , Roy Denis-Claude , Bhatia Ravi , Perrotti Danilo 
Published: June 2012

Abstract
Background: The success of tyrosine kinase inhibitors (TKIs) depends on the addiction of Philadelphia-positive (Ph+) CML progenitors to BCR-ABL1 kinase activity. However, CML quiescent hematopoietic stem cells (HSC) are TKI-resistant and represent an active disease reservoir. We hypothesize that this innate drug-resistance depends on inhibition of the tumor suppressor protein phosphatase 2A (PP2A). PP2A can be reactivated by FTY720, a drug that targets CML but not normal progenitors. Here we investigated the mechanism controlling survival/self-renewal of quiescent leukemic HSCs and their sensitivity to PP2A-activating drugs.
Methods: HSCs from CML (n=68) and healthy (n=12) donors were FACS-isolated, and the biologic importance of PP2A inhibition and pharmacologic PP2A activation on their survival/self-renewal was assessed by BM serial transplantation; CFSE and Annexin-V staining; LTC-IC and CFC/replating assays; lentiviral shRNA/cDNA-transduction; LEF/TCF and proximity-ligation assays; Western blot, confocal microscopy and FACS analyses.
Results: We observed increased BCR-ABL1 expression with impaired kinase activity in quiescent CML HSCs, in which BCR-ABL1 per se is required for induction of JAK2 that subsequently activated β-catenin and inhibited PP2A. In fact, PP2A was suppressed in CML but not normal CD34+/CD38−/CD90+ HSCs. FTY720 and/or its non-immunosuppressive (S)-FTY720-OMe derivative markedly reduced survival and self-renewal of CML but not normal quiescent HSCs through BCR-ABL1 kinase-independent and PP2A-mediated JAK2 and β-catenin inhibition. Importantly, FTY720 also strongly diminished BCR-ABL1+ LT-HSC frequency in serial BM transplantation assays.
Conclusions: The pharmacologic targeting of the newly-identified BCR-ABL1 kinase-independent JAK2/β-catenin interplay in quiescent HSCs with FTY720 and its derivatives, might lead to cessation of lifelong patient dependence on TKIs.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-109. doi:10.1158/1538-7445.AM2011-LB-109