Project description:Proliferating tumor cells use aerobic glycolysis to support their high metabolic demands. Paradoxically, increased glycolysis is often accompanied by expression of the lower activity PKM isoform, effectively constraining lower glycolysis. Here, we report the discovery of novel PKM activators with a unique allosteric binding mode. Characterization of how these compounds impact cancer cells revealed an unanticipated link between glucose and amino acid metabolism. PKM activation resulted in a metabolic rewiring of cancer cells manifested by a profound dependency on the non-essential amino acid serine for continued cell proliferation. Induction of serine auxotrophy by PKM activation was accompanied by reduced carbon flow into the serine biosynthetic pathway and increased expression of high affinity serine transporters. These data support the hypothesis that PKM expression confers metabolic flexibility to cancer cells that allows adaptation to nutrient stress. A549 cancer cells were treated with compound-16 for up to 24 hours in the presence and absence of serine in the media.
Project description:Proliferating tumor cells use aerobic glycolysis to support their high metabolic demands. Paradoxically, increased glycolysis is often accompanied by expression of the lower activity PKM isoform, effectively constraining lower glycolysis. Here, we report the discovery of novel PKM activators with a unique allosteric binding mode. Characterization of how these compounds impact cancer cells revealed an unanticipated link between glucose and amino acid metabolism. PKM activation resulted in a metabolic rewiring of cancer cells manifested by a profound dependency on the non-essential amino acid serine for continued cell proliferation. Induction of serine auxotrophy by PKM activation was accompanied by reduced carbon flow into the serine biosynthetic pathway and increased expression of high affinity serine transporters. These data support the hypothesis that PKM expression confers metabolic flexibility to cancer cells that allows adaptation to nutrient stress.
Project description:Although 3-Phosphoinositide-dependent protein kinase-1 (PDK1) has been predominately linked to PI3K-AKT pathway, it may also evoke additional signaling outputs to promote tumorigenesis. Here we report that PDK1 directly induces phosphorylation of Polo-like kinase 1 (PLK1), which in turn induces Myc phosphorylation and protein accumulation. We show that PDK1-PLK1-Myc signaling is critical for cancer cell growth and survival and small molecule inhibition of PDK1/PLK1 provides an effective approach for therapeutic targeting Myc-dependency. Intriguingly, PDK1-PLK1-Myc signaling induces an embryonic stem cell-like gene signature associated with aggressive tumor behaviors and is a robust signaling axis driving cancer stem cell (CSC) self renewal. Finally, we show that PLK1 inhibitor synergizes with mTOR inhibitor to induce synergistic anti-tumor effect in colorectal cancer by antagonizing a compensatory Myc induction. These findings identify a novel pathway in human cancer and CSC activation and provide a therapeutic strategy for targeting Myc-associated tumorigenesis and therapeutic resistance. Gene expression profiling of Human Embryonic Kidney Cells (HEK-TERV) under different conditions: PMN, PDK1, MYC and E545K
Project description:Defective arginine synthesis, due to the silencing of argininosuccinate synthase 1 (ASS1), is a common metabolic vulnerability in cancer, known as arginine auxotrophy. Understanding how arginine depletion kills arginine-auxotrophic cancer cells will facilitate the development of anti-cancer therapeutic strategies. Here we show that depletion of extracellular arginine in arginine-auxotrophic cancer cells causes mitochondrial distress and transcriptional reprogramming. Mechanistically, arginine starvation induces asparagine synthetase (ASNS), depleting these cancer cells of aspartate, and disrupting their malate-aspartate shuttle. Supplementation of aspartate, depletion of mitochondria, and knockdown of ASNS all protect the arginine-starved cells, establishing the causal effects of aspartate depletion and mitochondrial dysfunction on the arginine starvation-induced cell death. Furthermore, dietary arginine restriction reduced tumor growth in a xenograft model of ASS1-deficient breast cancer. Our data challenge the view that ASNS promotes homeostasis, arguing instead that ASNS-induced aspartate depletion promotes cytotoxicity, which can be exploited for anti-cancer therapies.
Project description:New approaches to cancer therapies could benefit from a better understanding of the molecular determinants critical to tumor initiating cells (TICs). Here we show that the metabolic enzyme glycine decarboxylase (GLDC) is critical for TICs in non-small cell lung cancer (NSCLC). From a broad range of primary NSCLC tumors, we isolated CD166+ lung TICs that consistently initiated tumorigenesis in NOD/SCID Il2rγ-/- mice. Lung TICs express high levels of the oncogenic stem cell factor LIN28B and the metabolic enzyme GLDC. Over-expression of GLDC and other glycine/serine metabolism enzymes, but not catalytically inactive GLDC, promotes cellular transformation and tumorigenesis. Metabolomic analysis found that GLDC induces dramatic changes in glycolysis and glycine/serine metabolism, leading to changes in pyrimidine metabolism to regulate cancer cell proliferation. Clinically, GLDC over-expression, observed in multiple cancer types, predicts poorer survival in lung cancer patients. Our findings establish a novel link between glycine metabolism and tumorigenesis, and provide novel targets for advancing anti-cancer therapy. Total RNA obtained from tumor sphere compared to CD166+ and CD166- selected cells of xenograft, primary tumor and normal donors
Project description:Oncogenic KRAS induces arginine auxotrophy in non-small cell lung cancer and confers a therapeutic vulnerability to SLC7A1 inhibition