Project description:Many cancers rely on glycolytic metabolism to fuel rapid proliferation. This has spurred interest in designing drugs that target tumor glycolysis such as AZD3965, a small molecule inhibitor of Monocarboxylate Transporter 1 (MCT1) currently undergoing Phase I evaluation for cancer treatment. Since MCT1 mediates proton-linked transport of monocarboxylates such as lactate and pyruvate across the plasma membrane (Halestrap and Meredith, 2004), AZD3965 is thought to block tumor growth through disruption of lactate transport and glycolysis. Here we show that MCT1 inhibition impairs proliferation of glycolytic breast cancer cells that express MCT4 via disruption of pyruvate rather than lactate export. We found that MCT1 expression is elevated in glycolytic breast tumors and cell lines as well as in malignant breast and lung tissues. High MCT1 expression predicts poor prognosis in breast and lung cancer patients. Stable knockdown and AZD3965-mediated inhibition of MCT1 promote oxidative metabolism. Acute inhibition of MCT1 reduces pyruvate export rate but does not consistently alter lactate transport or glycolytic flux in breast cancer cells that also express MCT4. Despite the lack of glycolysis impairment, MCT1 loss-of-function decreases breast cancer cell proliferation and blocks growth of mammary fat pad xenograft tumors. Our data suggest that MCT1 expression is elevated in glycolytic cancers to promote pyruvate export, which when inhibited enhances oxidative metabolism and reduces proliferation. This study presents an alternative molecular consequence of MCT1 inhibitors that further supports their use as anti-cancer therapeutics. Since MCT1 levels are elevated in glycolytic and malignant breast tumors, we hypothesized that MCT1 may contribute to the Warburg effect metabolic phenotype. To test this hypothesis, we generated whole genome microarray data from breast cancer cell lines either a) expressing a short hairpin (sh)RNA-mediated stable knockdown of MCT1; or b) treated for 24 hours with an MCT1 inhibitor (AZD3965). Scramble shRNA or DMSO were used as controls, and all conditions were analzed in triplicate. The cell lines used â HS578T, SUM149PT, and SUM159PT â are among the most glycolytic in a panel of 31 breast cancer cell lines.
Project description:Many cancers rely on glycolytic metabolism to fuel rapid proliferation. This has spurred interest in designing drugs that target tumor glycolysis such as AZD3965, a small molecule inhibitor of Monocarboxylate Transporter 1 (MCT1) currently undergoing Phase I evaluation for cancer treatment. Since MCT1 mediates proton-linked transport of monocarboxylates such as lactate and pyruvate across the plasma membrane (Halestrap and Meredith, 2004), AZD3965 is thought to block tumor growth through disruption of lactate transport and glycolysis. Here we show that MCT1 inhibition impairs proliferation of glycolytic breast cancer cells that express MCT4 via disruption of pyruvate rather than lactate export. We found that MCT1 expression is elevated in glycolytic breast tumors and cell lines as well as in malignant breast and lung tissues. High MCT1 expression predicts poor prognosis in breast and lung cancer patients. Stable knockdown and AZD3965-mediated inhibition of MCT1 promote oxidative metabolism. Acute inhibition of MCT1 reduces pyruvate export rate but does not consistently alter lactate transport or glycolytic flux in breast cancer cells that also express MCT4. Despite the lack of glycolysis impairment, MCT1 loss-of-function decreases breast cancer cell proliferation and blocks growth of mammary fat pad xenograft tumors. Our data suggest that MCT1 expression is elevated in glycolytic cancers to promote pyruvate export, which when inhibited enhances oxidative metabolism and reduces proliferation. This study presents an alternative molecular consequence of MCT1 inhibitors that further supports their use as anti-cancer therapeutics.
Project description:Platinum compounds display clinical activity against a wide variety of solid tumors. However, resistance to these agents is a major limitation in cancer therapy. Reduced platinum uptake and increased platinum export are examples of resistance mechanisms that limit the extent of DNA damage. Here, we report the discovery and characterization of the role of ATP11B, a P-type ATPase membrane protein, in cisplatin resistance. ATP11B gene silencing restored the sensitivity of ovarian cancer cell lines to cisplatin in vitro. Combined therapy of cisplatin and ATP11B-siRNA significantly decreased cancer growth in mice bearing ovarian tumors derived from cisplatin-sensitive and -resistant cells. In vitro mechanistic studies on cellular platinum content and cisplatin efflux-kinetics indicated that ATP11B enhances the export of cisplatin from cells. The co-localization of ATP11B with fluorescent cisplatin and with vesicular trafficking proteins such as syntaxin-6 (STX6) and vesicular associated membrane protein 4 (VAMP4) strongly suggests that ATP11B contributes to secretory vesicular transport of cisplatin from Golgi to plasma membrane. In conclusion, silencing ATP11B expression might be a therapeutic strategy to overcome cisplatin resistance. We performed the transfection of control-siRNA and ATP11B-siRNA to both cisplatin-sensitive A2780-PAR and cisplatin-resistant A2780-CP20 cells respectively.
Project description:Pyruvate is a key metabolite in glycolysis and tricarboxylic acid (TCA) cycle. Exogenous pyruvate modulates metabolism, provides cellular protection, and is essential for the maintenance of human preimplantation embryos and human embryonic stem cells (hESCs). However, little is known about how pyruvate contributes to cell fate determination during epiblast stage. In this study, we used hESCs as a model to demonstrate that elevated exogenous pyruvate shifts metabolic balance towards oxidative phosphorylation in both maintenance and differentiation conditions. During differentiation, pyruvate potentiates mesoderm and endoderm lineage specification. Pyruvate production and its mitochondrial metabolism are required in BMP4-induced mesoderm differentiation. However, the TCA cycle metabolites do not have the same effect as pyruvate on differentiation. Further study shows that pyruvate increases AMP/ATP ratio, activates AMPK, and then modulates the mTOR pathway to enhance mesoderm differentiation. This study reveals that exogenous pyruvate not only controls metabolism, but also modulates signaling pathways in hESC differentiation.
Project description:Platinum compounds display clinical activity against a wide variety of solid tumors. However, resistance to these agents is a major limitation in cancer therapy. Reduced platinum uptake and increased platinum export are examples of resistance mechanisms that limit the extent of DNA damage. Here, we report the discovery and characterization of the role of ATP11B, a P-type ATPase membrane protein, in cisplatin resistance. ATP11B gene silencing restored the sensitivity of ovarian cancer cell lines to cisplatin in vitro. Combined therapy of cisplatin and ATP11B-siRNA significantly decreased cancer growth in mice bearing ovarian tumors derived from cisplatin-sensitive and -resistant cells. In vitro mechanistic studies on cellular platinum content and cisplatin efflux-kinetics indicated that ATP11B enhances the export of cisplatin from cells. The co-localization of ATP11B with fluorescent cisplatin and with vesicular trafficking proteins such as syntaxin-6 (STX6) and vesicular associated membrane protein 4 (VAMP4) strongly suggests that ATP11B contributes to secretory vesicular transport of cisplatin from Golgi to plasma membrane. In conclusion, silencing ATP11B expression might be a therapeutic strategy to overcome cisplatin resistance.
Project description:Pyruvate is a glycolytic metabolite used for energy production and macromolecule biosynthesis. However, little is known about its potential functions in tumorigenesis. Here,we report that exogenous pyruvate inhibits the proliferation of different types of cancer cells. This inhibitory effect of pyruvate on cell growth is attributed to its function as a signal molecule to repress histone gene expression, which leads to less compact chromatin structure and misregulation of genome-wide gene expression. Pyruvate represses histone gene expression by inducing the expression of NAD + biosynthesis enzyme, nicotinamide phosphoribosyltransferase (NAMPT), which increases NAD + levels and NAD + /NADH ratio. This increase activates the histone deacetylase activity of SIRT1. Chromatin immunoprecipitation analysis indicates that pyruvate enhances SIRT1 binding at histone gene promoters where it reduces histone acetylation. Although pyruvate delays cell entry into S phase, pyruvate represses histone gene expression independent of cell cycle progression. Moreover, we find that administration of pyruvate significantly reduces histone expression and retards tumor growth in xenograft mice without significant side effects. Using tissues from cervical cancer patients, we find intracellular pyruvate concentrations inversely correlate with histone protein levels. Together, we uncover a previously unknown function of pyruvate in histone gene expression and characterize pyruvate as a potential anti-cancer agent.
Project description:Technical advances in next generation sequencing (NGS) has revolutionized system-based analysis of genome-wide expression, cellular pathways and responses. We performed this study to establish the transcriptomic profiles of human prostate cancer cell lines exposed to conditioned media from human primary stromal cells engineered to express pyruvate dehydrogenase kinase 4 (PDK4), a key enzyme that is correlated with glucose metabolism, negatively regulates the conversion of pyruvate to acetyl-CoA and plays important roles in cancer progression and multiple other pathological events.
Project description:Mutations mimicking growth factor-induced proliferation and motility characterize aggressive subtypes of mammary tumors. To unravel novel players, we applied phosphoproteomics on untransformed mammary cells, which were pre-stimulated with the epidermal growth factor (EGF). This analysis identified ladinin-1 (LAD1), a hitherto poorly characterized protein, as a phosphor-effector of the EGF-to-ERK pathway. We report that LAD1 is essential for mammary cell proliferation and migration. LAD1 is transcriptionally induced, undergoes phosphorylation by EGF and partly co-localizes with actin stress fibers. Yeast 2-hybrids, proximity ligation and co-immunoprecipitation assays revealed that LAD1 binds with filamins, actin cross-linking proteins. Co-sedimentation analyses attribute to LAD1 a role in actin treadmilling, probably in collaboration with SFN/14-3-3sigma. Depletion of LAD1 led to a decrease in transcripts relevant to cell survival, and inhibited growth of mammary xenografts in an animal model. Furthermore, LAD1 is highly expressed in two aggressive subtypes of breast cancer, as well as predicts poor patient prognosis. This study identifies a new cytoskeletal component essential for cell migration and for the acquisition of oncogenic attributes by human mammary tumors.
Project description:The yeast mRNA export adaptor Yra1 binds the Pcf11 subunit of cleavage-polyadenylation factor CF1A linking export to 3'-end formation. We found a surprising consequence of this interaction is that Yra1 influences cleavage-polyadenylation. Yra1 competes with the CF1A subunit, Clp1, for binding to Pcf11, and excess Yra1 inhibits 3' processing in vitro. Release of Yra1 at the 3' ends of genes coincides with recruitment of Clp1, and depletion of Yra1 enhances Clp1 recruitment within some genes. These results suggest that CF1A is not necessarily recruited as a complete unit, but instead Clp1 can be incorporated co-transcriptionally in a process regulated by Yra1. Yra1 depletion causes widespread changes in poly(A) site choice particularly at sites where the efficiency element is divergently positioned. We propose that one way Yra1 modulates cleavage-polyadenylation is by influencing co-transcriptional assembly of the CF1A/B 3' processing factor. Key Words: Yra1, cleavage-polyadenylation, mRNA export, Pcf11, Clp1, Sub2, alternative polyadenylation mRNA poly (A) sites were mapped by sequencing 3' ends in WT and Yra1-depleted cells using a GAL1-YRA1 mutant. RNA seq of mRNA 3' ends using Illumina platform.
Project description:Cancer cells often metastasize by undergoing an epithelial-mesenchymal transition (EMT). Although abundance of CD8+ T-cells in the tumor microenvironment correlates with improved survival, mesenchymal cancer cells acquire greater resistance to antitumor immunity in some cancers. We hypothesized the EMT modulates the immune response to ovarian cancer. Here we show that cancer cells from infiltrated/inflamed tumors possess more mesenchymal cells, than excluded and desert tumors. We also noted high expression of LGALS3 is associated with EMT in vivo, a finding validated with in vitro EMT models. Dissecting the cellular communications among populations in the tumor revealed that mesenchymal cancer cells in infiltrated tumors communicate through LGALS3 to LAG3 receptor expressed by CD8+ T cells. We found CD8+ T cells express high levels of LAG3, a marker of T cell exhaustion. The results indicate that EMT in ovarian cancer cells promotes interactions between cancer cells and T cells through the LGALS3 - LAG3 axis, which could increase T cell exhaustion in infiltrated tumors, dampening antitumor immunity.