AMPK is a metabolic sensor that helps maintain cellular energy homeostasis. Despite evidence linking AMPK with tumor suppressor functions, the role of AMPK in tumorigenesis and tumor metabolism ...is unknown. Here we show that AMPK negatively regulates aerobic glycolysis (the Warburg effect) in cancer cells and suppresses tumor growth in vivo. Genetic ablation of the α1 catalytic subunit of AMPK accelerates Myc-induced lymphomagenesis. Inactivation of AMPKα in both transformed and nontransformed cells promotes a metabolic shift to aerobic glycolysis, increased allocation of glucose carbon into lipids, and biomass accumulation. These metabolic effects require normoxic stabilization of the hypoxia-inducible factor-1α (HIF-1α), as silencing HIF-1α reverses the shift to aerobic glycolysis and the biosynthetic and proliferative advantages conferred by reduced AMPKα signaling. Together our findings suggest that AMPK activity opposes tumor development and that its loss fosters tumor progression in part by regulating cellular metabolic pathways that support cell growth and proliferation.
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► Loss of AMPKα1 cooperates with the Myc oncogene to accelerate lymphomagenesis ► AMPKα dysfunction enhances aerobic glycolysis (Warburg effect) ► Inhibiting HIF-1α reverses the metabolic effects of AMPKα loss ► HIF-1α mediates the growth advantage of tumors with reduced AMPK signaling
The RAS-RAF-MEK-ERK signaling cascade is among the most frequently mutated pathways in human cancer. Approximately 50% of melanoma patients possess a druggable hotspot V600E/K mutation in the BRAF ...protein kinase. FDA-approved combination therapies of BRAF and MEK inhibitors are available that provide survival benefits to patients with a BRAF V600 mutation. Non-V600 BRAF mutants are found in many cancers, and are more prevalent than V600 mutations in certain tumor types. For example, between 50-80% of BRAF mutations in non-small cell lung cancer and 22-30% in colorectal cancer encode for non-V600 mutants. As next generation sequencing becomes increasingly used in clinical practice, oncologists are frequently identifying non-V600 BRAF mutations in their patient's tumors, but are uncertain of viable therapeutic options that could be employed for optimal treatment. From recent studies, a new classification system is emerging for BRAF mutations based on biochemical and signaling mechanisms associated with these mutants. Class I BRAF mutations affect amino acid V600 and signal as RAS-independent active monomers, class II mutations function as RAS-independent activated dimers, and class III mutations are kinase impaired but increase signaling through the MAPK pathway due to enhanced RAS binding and subsequent CRAF activation. These distinct classes of BRAF mutations predict response to targeted therapies and have important implications for future drug development. Herein, we discuss pre-clinical and clinical findings that may lead to improved treatments for all classes of BRAF mutant cancers.
Highlights • Cancer cells seed and co-opt “pre-existing” niches that provide critical physiological functions within the target tissue. • Cancer cells can actively induce the formation of ...“pre-metastatic” niches prior to their arrival in the metastatic site. • Metastatic niches are composed of ECM components, tissue-resident cells and infiltrating stromal cells. • Niches support tumour cell seeding, extravasation, survival, proliferation and invasion to establish macro-metastases. • Metabolic coupling between cancer cells and stromal cells is emerging as an important process during metastasis.
Metabolic reprogramming is a hallmark of cellular transformation, yet little is known about metabolic changes that accompany tumor metastasis. Here we show that primary breast cancer cells display ...extensive metabolic heterogeneity and engage distinct metabolic programs depending on their site of metastasis. Liver-metastatic breast cancer cells exhibit a unique metabolic program compared to bone- or lung-metastatic cells, characterized by increased conversion of glucose-derived pyruvate into lactate and a concomitant reduction in mitochondrial metabolism. Liver-metastatic cells displayed increased HIF-1α activity and expression of the HIF-1α target Pyruvate dehydrogenase kinase-1 (PDK1). Silencing HIF-1α reversed the glycolytic phenotype of liver-metastatic cells, while PDK1 was specifically required for metabolic adaptation to nutrient limitation and hypoxia. Finally, we demonstrate that PDK1 is required for efficient liver metastasis, and its expression is elevated in liver metastases from breast cancer patients. Our data implicate PDK1 as a key regulator of metabolism and metastatic potential in breast cancer.
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•Breast cancer cells display unique metabolic signatures depending on metastatic site•HIF-1α/PDK1 promotes glycolytic metabolism in liver-metastatic breast cancer cells•PDK1 is required for efficient formation of liver metastases•PDK1 expression is elevated in human liver metastases
Dupuy et al. reveal that primary breast cancer cells display extensive metabolic heterogeneity and differentially engage glycolysis or OXPHOS depending on their site of metastasis (liver, lung, or bone). Liver metastases rely on a HIF-1α/PDK1-dependent axis for their intrinsic metabolic reprogramming, which enables their efficient colonization and growth in the liver.
Single-cell technologies have revealed the complexity of the tumour immune microenvironment with unparalleled resolution
. Most clinical strategies rely on histopathological stratification of tumour ...subtypes, yet the spatial context of single-cell phenotypes within these stratified subgroups is poorly understood. Here we apply imaging mass cytometry to characterize the tumour and immunological landscape of samples from 416 patients with lung adenocarcinoma across five histological patterns. We resolve more than 1.6 million cells, enabling spatial analysis of immune lineages and activation states with distinct clinical correlates, including survival. Using deep learning, we can predict with high accuracy those patients who will progress after surgery using a single 1-mm
tumour core, which could be informative for clinical management following surgical resection. Our dataset represents a valuable resource for the non-small cell lung cancer research community and exemplifies the utility of spatial resolution within single-cell analyses. This study also highlights how artificial intelligence can improve our understanding of microenvironmental features that underlie cancer progression and may influence future clinical practice.
Increased macroautophagy/autophagy and lysosomal activity promote tumor growth, survival and chemo-resistance. During acute starvation, autophagy is rapidly engaged by AMPK (AMP-activated protein ...kinase) activation and MTOR (mechanistic target of rapamycin kinase) complex 1 (MTORC1) inhibition to maintain energy homeostasis and cell survival. TFEB (transcription factor E3) and TFE3 (transcription factor binding to IGHM enhancer 3) are master transcriptional regulators of autophagy and lysosomal activity and their cytoplasm/nuclear shuttling is controlled by MTORC1-dependent multisite phosphorylation. However, it is not known whether and how the transcriptional activity of TFEB or TFE3 is regulated. We show that AMPK mediates phosphorylation of TFEB and TFE3 on three serine residues, leading to TFEB and TFE3 transcriptional activity upon nutrient starvation, FLCN (folliculin) depletion and pharmacological manipulation of MTORC1 or AMPK. Collectively, we show that MTORC1 specifically controls TFEB and TFE3 cytosolic retention, whereas AMPK is essential for TFEB and TFE3 transcriptional activity. This dual and opposing regulation of TFEB and TFE3 by MTORC1 and AMPK is reminiscent of the regulation of another critical regulator of autophagy, ULK1 (unc-51 like autophagy activating kinase 1). Surprisingly, we show that chemoresistance is mediated by AMPK-dependent activation of TFEB, which is abolished by pharmacological inhibition of AMPK or mutation of serine 466, 467 and 469 to alanine residues within TFEB. Altogether, we show that AMPK is a key regulator of TFEB and TFE3 transcriptional activity, and we validate AMPK as a promising target in cancer therapy to evade chemotherapeutic resistance.
Abbreviations: ACACA: acetyl-CoA carboxylase alpha; ACTB: actin beta; AICAR: 5-aminoimidazole-4-carboxamide ribonucleotide; AMPK: AMP-activated protein kinase; AMPKi: AMPK inhibitor, SBI-0206965; CA: constitutively active; CARM1: coactivator-associated arginine methyltransferase 1; CFP: cyan fluorescent protein; CLEAR: coordinated lysosomal expression and regulation; DKO: double knock-out; DMEM: Dulbecco's modified Eagle's medium; DMSO: dimethyl sulfoxide; DQ-BSA: self-quenched BODIPY® dye conjugates of bovine serum albumin; EBSS: Earle's balanced salt solution; FLCN: folliculin; GFP: green fluorescent protein; GST: glutathione S-transferases; HD: Huntington disease; HTT: huntingtin; KO: knock-out; LAMP1: lysosomal associated membrane protein 1; MEF: mouse embryonic fibroblasts; MITF: melanocyte inducing transcription factor; MTORC1: MTOR complex 1; PolyQ: polyglutamine; RPS6: ribosomal protein S6; RT-qPCR: reverse transcription quantitative polymerase chain reaction; TCL: total cell lysates; TFE3: transcription factor binding to IGHM enhancer 3; TFEB: transcription factor EB; TKO: triple knock-out; ULK1: unc-51 like autophagy activating kinase 1.
Pediatric midline high-grade astrocytomas (mHGAs) are incurable with few treatment targets identified. Most tumors harbor mutations encoding p.Lys27Met in histone H3 variants. In 40 treatment-naive ...mHGAs, 39 analyzed by whole-exome sequencing, we find additional somatic mutations specific to tumor location. Gain-of-function mutations in ACVR1 occur in tumors of the pons in conjunction with histone H3.1 p.Lys27Met substitution, whereas FGFR1 mutations or fusions occur in thalamic tumors associated with histone H3.3 p.Lys27Met substitution. Hyperactivation of the bone morphogenetic protein (BMP)-ACVR1 developmental pathway in mHGAs harboring ACVR1 mutations led to increased levels of phosphorylated SMAD1, SMAD5 and SMAD8 and upregulation of BMP downstream early-response genes in tumor cells. Global DNA methylation profiles were significantly associated with the p.Lys27Met alteration, regardless of the mutant histone H3 variant and irrespective of tumor location, supporting the role of this substitution in driving the epigenetic phenotype. This work considerably expands the number of potential treatment targets and further justifies pretreatment biopsy in pediatric mHGA as a means to orient therapeutic efforts in this disease.
The cytostatic and apoptotic functions of transforming growth factor- beta (TGF- beta ) help restrain the growth of mammalian tissues; loss of these effects leads to hyperproliferative disorders and ...is common in cancer. However, tumour cells that are relieved from TGF- beta growth constraints might then overproduce this cytokine to create a local immunosuppressive environment that fosters tumour growth and exacerbates the invasive and metastatic behaviour of the tumour cells themselves. For these reasons, there is a growing interest in understanding and therapeutically targeting TGF- beta -mediated processes in cancer progression. Members of the transforming growth factor- beta (TGF- beta ) family maintain homeostasis in many organ systems under normal physiological conditions. Antiproliferative and apoptotic responses to TGF- beta in epithelial, endothelial, neuronal and haematopoietic cells effectively limit the growth of these cell lineages. The importance of TGF- beta as a growth suppressor is demonstrated by the disruption of TGF- beta signalling components in human cancers. Certain tumours develop resistance to TGF- beta growth-suppressive effects in the absence of mutations that disrupt the core TGF- beta pathway. TGF- beta induces epithelial-mesenchymal transitions (EMT) in cancer cells, and pro-angiogenic and immunosuppressive effects on the tumour microenvironment, all of which promote cancer progression. TGF- beta acts as an important mediator of metastasis to specific organ sites - such as breast cancer metastasis to the bone - by increasing the expression of tissue-specific metastasis genes.
Neutrophils are phenotypically heterogeneous and exert either anti- or pro-metastatic functions. We show that cancer-cell-derived G-CSF is necessary, but not sufficient, to mobilize immature ...low-density neutrophils (iLDNs) that promote liver metastasis. In contrast, mature high-density neutrophils inhibit the formation of liver metastases. Transcriptomic and metabolomic analyses of high- and low-density neutrophils reveal engagement of numerous metabolic pathways specifically in low-density neutrophils. iLDNs exhibit enhanced global bioenergetic capacity, through their ability to engage mitochondrial-dependent ATP production, and remain capable of executing pro-metastatic neutrophil functions, including NETosis, under nutrient-deprived conditions. We demonstrate that NETosis is an important neutrophil function that promotes breast cancer liver metastasis. iLDNs rely on the catabolism of glutamate and proline to support mitochondrial-dependent metabolism in the absence of glucose, which enables sustained NETosis. These data reveal that distinct pro-metastatic neutrophil populations exhibit a high degree of metabolic flexibility, which facilitates the formation of liver metastases.
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•G-CSF is required, but not sufficient, to mobilize immature low-density neutrophils•Immature low-density neutrophils are defined by a C/EBPε transcriptional signature•Immature low-density neutrophils promote the formation of liver metastases•Immature low-density neutrophils have a higher global bioenergetic capacity
Hsu et al. demonstrate that tumor-derived G-CSF, in concert with additional factors, mobilizes immature low-density neutrophils (iLDNs) that promote breast cancer liver metastasis. iLDNs are able to perform pro-metastatic functions under metabolically challenging conditions, such as low glucose, due to their enhanced global bioenergetic capacity.
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