Project description:Gene expression analysis of MDA-MB-231 breast cancer cells cultured in suspension {and stably expressing control shRNA, shPHLPP2 or GFP-Akt DD (GFP-HA-Akt-T308D S473D)}. Results provide insights into regulation of molecular pathways by PHLPP2 and Akt signaling in matrix deprived condition.
Project description:Matrix-deprivation stress leads to cell-death by anoikis, whereas overcoming anoikis is critical for cancer metastasis. Work from our lab and others has identified a crucial role for the cellular energy sensor AMPK in anoikis-resistance, highlighting a key role for metabolic reprogramming in stress survival. Protein synthesis is a major energy-consuming process that is tightly regulated under stress. Although an increase in protein synthesis in AMPK-depleted experimentally-transformed MEFs has been associated with anoikis, the status and regulation of protein translation in epithelial-origin cancer cells facing matrix-detachment remains largely unknown. Our study shows that protein translation is mechanistically abrogated at both initiation and elongation stages by the activation of the unfolded protein response (UPR) pathway and inactivation of elongation factor eEF2, respectively. Additionally, we show inhibition of the mTORC1 pathway known for regulation of canonical protein synthesis. We further functionally assay this inhibition using SUnSET assay, which demonstrates repression of global protein synthesis in MDA-MB-231 and MCF7 breast cancer cells when subjected to matrix-deprivation. In order to gauge the translational status of matrix-deprived cancer cells, we undertook polysome profiling. Our data revealed reduced but continuous mRNA translation under matrix-deprivation stress. An integrated analysis of transcriptomic and proteomic data further identifies novel targets that may aid cellular adaptations to matrix-deprivation stress and can be explored for therapeutic intervention.
Project description:Gene expression analysis of MDA-MB-231 breast cancer cells cultured in attached (treated with vehicle DMSO or A76) or suspension (and stably expressing control shRNA or shAMPKα2). Results provide insights into changes in molecular pathways and its regulation by AMPK
Project description:Extracellular Matrix 1(ECM1) expression is increased in multiple tumor cell lines and primary cancers. Activator protein 2C (TFAP2C) is a potent regulator of ECM1 transcription. TFAP2C may contribute to the increased ECM1 expression noted in many cancers. This is the first report identifying the minimal promoter region of the human ECM1 gene and its regulation by TFAP2C Human A375 melanoma cells were assessed for mRNA and protein expression of ECM1. A mininal promoter region for ECM1 transactivation was identified. ECM1 expression was regulated in part by TFAP2C, and in ChIP-Seq experiments, TFAP2C was found to bind directly to the ECM1 gene in A375 melanoma cells and in MCF7 breast cancer cells.
Project description:This SuperSeries is composed of the following subset Series: GSE22533: Breast cancer cells resistant to hormone deprivation maintain an estrogen receptor alpha-dependent, E2F-directed transcriptional program GSE27300: Estrogen-independent genomic ER binding analysis Refer to individual Series
Project description:Background: cancer cells rely on glycolysis as main ATP source (Warbürg effect). Tumor-initiating cells (TICs) are the fraction of cells that give raise and repopulate tumors. TICs are exposed to prolonged periods of oxygen and glucose deprivation (OGD), as they live in a hypoxic niche and they withstand prolonged lack of blood vessels during initial tumorigenesis or metastasis formation (avascular phase). Warbürg effect is energetically inefficient; we hypothesize that TICs might have differential metabolic features. Tumor eradication requires killing TICS; finding such features would have therapeutic implications. Methodology/principal findings: 106 MDA-MB-231 breast-cancer cells (hereafter Wt) were exposed for 5 weeks to 0.2% oxygen and 0.1g/l glucose, recovering 9 clones. Both flow-cytometry (50-fold enrichment in the CD24-/CD44+/CD133+ population) and xenografts in NOD/SCID mice using 100 cells (75% vs. 16% engraftment) suggest that OGD-resistant clones are true TICs (hereafter “TIC clones”). TIC clones showed a 30-fold higher replication and viability (BRDU incorporation, colony assay) than Wt. When exposed to OGD, ATP-production dropped 5-fold in WT, but was maintained in TIC clones by increasing 5-fold the fatty acid and oxygen consumption. These properties were explained by lack of upregulation of HIF-1 alpha and PDK1, as well as an increase in ATP-synthase. Analysis with metabolic inhibitors (2-deoxyglucose, antimycin-A) confirmed glycolysis and mitochondrial respiration as main routes of metabolism for Wt and TIC clones respectively. Metabolomics revealed that glutamine catabolism generated the NADPH required to quench reactive oxygen species generated during mitochondrial respiration in TIC clones. Glutamine deprivation or mitochondrial blockers were able to abrogate the viability of TIC clones. Conclusions/significance: the TIC-fraction of a cancer cell population withstands prolonged OGD by switching from the Warbürg effect to mitochondrial respiration. Targeting this metabolic feature abrogates the survival of TICs.
Project description:To ensure their high proliferation rate, tumor cells display an iron metabolic disorder with increased iron needs, making them more susceptible to iron deprivation. This vulnerability could be a therapeutic target. In breast cancers, the development of new therapeutic approaches is urgently needed for patients with triple negative tumors which frequently relapse after chemotherapy and suffer from a lack of targeted therapies. Anticancer activity of iron chelator deferasirox (DFX) assessed in monotherapy do not appear to be effective enough to treat breast cancer progression. In this work, we demonstrated that DFX synergizes with standard chemotherapeutic agents such as with doxorubicin, cisplatin and carboplatin to inhibit cell proliferation and induce apoptosis and autophagy in TNBC cell lines. Moreover, the combination of DFX with doxorubicin and cyclophosphamide allowed to delay or avoid recurrences in breast cancer patient-derived xenografts without increasing the side-effects of chemotherapies alone or altering global iron storage of mice. Antitumor synergy of DFX and doxorubicin involves down-regulation of PI3K and NF-κB pathways. Furthermore, as TNBC patients with low iron tumor dynamic in their tumor present a good prognosis, we thought that iron deprivation mediated by iron chelators may all the more increase the effectiveness of conventional chemotherapies for TNBC treatments.