The protein kinase activity of fructokinase A specifies the antioxidant responses of tumor cells by phosphorylating p62

SLC27A5 inhibits cancer stem cells by inducing alternative polyadenylation of METTL14 in hepatocellular carcinoma

Solute carrier family 27 member 5 (SLC27A5/FATP5) is a liver-specific metabolic enzyme that plays a crucial role in fatty acid transport and bile acid metabolism. Deficiency of SLC27A5 promotes the progression of hepatocellular carcinoma (HCC) and is strongly associated with a poor prognosis. SLC27A5 exhibits noncanonical functions beyond its metabolic role; however, its specific mechanisms in hepatocarcinogenesis remain elusive and are therefore investigated in this study. Immunoprecipitation-mass spectrometry analysis showed that SLC27A5-interacting proteins were significantly enriched in alternative polyadenylation (APA). RNA-sequencing data provided evidence that SLC27A5 plays a global role in regulating APA events in HCC. Mechanistically, SLC27A5 facilitates the usage of the proximal polyadenylation site of METTL14 by downregulating the expression of the APA-associated factor PABPC1, resulting in the shortening of the METTL14-3'UTR and the conversion of METTL14-UL to METTL14-US. In contrast to METTL14-UL, METTL14-US escapes the inhibitory effect of miRNA targeting, leading to increased METTL14 expression. METTL14-US upregulation by SLC27A5 suppressed the stemness of HCC. Therefore, low levels of SLC27A5 and METTL14 may serve as reliable biomarkers for identifying poor prognosis in patients with HCC. In conclusion, SLC27A5/PABPC1 inhibits HCC stemness via APA-regulated expression of METTL14, providing potential avenues for the development of novel therapeutic strategies.

PCK1 inhibits cGAS-STING activation by consumption of GTP to promote tumor immune evasion

Hypoxia induces immunosuppressive phenotypes in tumor cells even in the presence of cytosolic DNA accumulation. The mechanisms by which tumor cells suppress hypoxia-induced cGAS-STING activation for immune evasion remain largely unclear. Here, we demonstrate that hypoxic stimulation induces JNK1/2-mediated S151 phosphorylation of phosphoenolpyruvate carboxykinase 1 (PCK1), a rate-limiting enzyme in gluconeogenesis. This phosphorylation triggers the interaction between PCK1 and cGAS. The PCK1 associated with cGAS competitively consumes GTP, a substrate shared by both PCK1 and cGAS. Consequently, PCK1 inhibits GTP-dependent cGAS activation and subsequent STING-promoted immune cell infiltration and activation in the tumor microenvironment, leading to promoted tumor growth in mice. The blockade of PCK1 function, in combination with anti-PD-1 antibody treatment, exhibits an additive therapeutic effect on tumor growth. Additionally, PCK1 S151 phosphorylation is inversely correlated with cGAS-STING activation in human breast cancer specimens and patient survival. These findings reveal a novel regulation of cGAS-STING pathway and uncover the metabolic control of immune response in tumor cells.

ERK-USP9X-coupled regulation of thymidine kinase 1 promotes both its enzyme activity-dependent and its enzyme activity-independent functions for tumor growth

Thymidine kinase 1 (TK1), a crucial enzyme in DNA synthesis, is highly expressed in various cancers. However, the mechanisms underlying its elevated expression and the implications for tumor metabolism remain unclear. Here we demonstrate that activation of growth factor receptors enhances TK1 expression. Treatment with epidermal growth factor or insulin-like growth factor 1 induces the binding of ERK1/2 to TK1 and subsequent TK1 S13/231 phosphorylation by ERK1/2. This modification recruits ubiquitin carboxyl-terminal hydrolase 9X to deubiquitylate TK1, preventing its proteasomal degradation. Stabilized TK1 not only enhances its enzyme activity-dependent deoxythymidine monophosphate production for DNA synthesis but also promotes glycolysis independently of its enzymatic activity by upregulating phosphofructokinase/fructose bisphosphatase type 3 expression. This dual role of TK1 drives the proliferation of human hepatocellular carcinoma cells and liver tumor growth in mice. Our findings reveal a crucial mechanism by which growth factors promote tumor development through TK1-mediated DNA synthesis and glycolysis and highlight TK1 as a potential molecular target for cancer treatment.

ADSL-generated fumarate binds and inhibits STING to promote tumour immune evasion

Highly aggressive tumours have evolved to restrain the cGAS-STING pathway for immune evasion, and the mechanisms underlying this hijacking remain unknown. Here we demonstrate that hypoxia induces robust STING activation in normal mammary epithelial cells but not in breast cancer cells. Mechanistically, adenylosuccinate lyase (ADSL), a key metabolic enzyme in de novo purine synthesis, is highly expressed in breast cancer tissues and is phosphorylated at T350 by hypoxia-activated IKKβ. Phosphorylated ADSL interacts with STING at the endoplasmic reticulum, where ADSL-produced fumarate binds to STING, leading to the inhibition of cGAMP binding to STING, STING activation and subsequent IRF3-dependent cytokine gene expression. Disrupting the ADSL-STING association promotes STING activation and blunts tumour growth. Notably, a combination treatment with ADSL endoplasmic reticulum translocation-blocking peptide and anti-PD-1 antibody induces an additive inhibitory effect on tumour growth accompanying a substantially increased immune response. Notably, ADSL T350 phosphorylation levels are inversely correlated with levels of STING activation and predicate poor prognosis in patients with breast cancer. These findings highlight a pivotal role of the metabolite fumarate in inhibiting STING activation and uncover new strategies to improve immune-checkpoint therapy by targeting ADSL-moonlighting function-mediated STING inhibition.

Targeting the Interplay Between Autophagy and the Nrf2 Pathway in Parkinson's Disease with Potential Therapeutic Implications

Parkinson's disease (PD) is a prevalent neurodegenerative disorder marked by the progressive degeneration of midbrain dopaminergic neurons and resultant locomotor dysfunction. Despite over two centuries of recognition as a chronic disease, the exact pathogenesis of PD remains elusive. The onset and progression of PD involve multiple complex pathological processes, with dysfunctional autophagy and elevated oxidative stress serving as critical contributors. Notably, emerging research has underscored the interplay between autophagy and oxidative stress in PD pathogenesis. Given the limited efficacy of therapies targeting either autophagy dysfunction or oxidative stress, it is crucial to elucidate the intricate mechanisms governing their interplay in PD to develop more effective therapeutics. This review overviews the role of autophagy and nuclear factor erythroid 2-related factor 2 (Nrf2), a pivotal transcriptional regulator orchestrating cellular defense mechanisms against oxidative stress, and the complex interplay between these processes. By elucidating the intricate interplay between these key pathological processes in PD, this review will deepen our comprehensive understanding of the multifaceted pathological processes underlying PD and may uncover potential strategies for its prevention and treatment.

Nicotinamide mononucleotide boosts the development of bovine oocyte by enhancing mitochondrial function and reducing chromosome lagging

Nicotinamide adenine dinucleotide (NAD(H)) and its metabolites function as crucial regulators of physiological processes, allowing cells to adapt to environmental changes such as nutritional deficiencies, genotoxic factors, disruptions in circadian rhythms, infections, inflammation, and exogenous substances. Here, we investigated whether elevated NAD(H) levels in oocytes enhance their quality and improve developmental competence following in vitro fertilization (IVF). Bovine cumulus-oocyte complexes (COCs) were matured in a culture medium supplemented with 0-100 μM nicotinamide mononucleotide (NMN), a precursor of NAD(H). The addition of NMN caused an increase in intracellular NAD(H) and nicotinamide adenine dinucleotide phosphate levels, leading to enhanced competence for development to the blastocyst stage after IVF. The increase in intracellular NAD(H) levels led to changes in the expression of mitochondria function-related genes. As a result, NMN supplementation increased the ratio of MitoTracker Orange fluorescence to nonyl acridine orange fluorescence, as well as adenosine triphosphate levels, while decreasing reactive oxygen species levels in the oocytes. NMN also lowered chromosome lagging during anaphase. These results suggest that increased NAD(H) levels in oocytes following NMN treatment enhances post-fertilization developmental competence through improved mitochondrial function.

Ferroptosis in hepatocellular carcinoma: Mechanisms and therapeutic implications

Ferroptosis is a novel form of oxidative cell death, in which highly expressed unsaturated fatty acids on the cell membrane are catalyzed by divalent iron or ester oxygenase to promote liposome peroxidation. This process reduces cellular antioxidant capacity, increases lipid reactive oxygen species, and leads to the accumulation of intracellular ferrous ions, which disrupts intracellular redox homeostasis and ultimately causes oxidative cell death. Studies have shown that ferroptosis induces an immune response that has a dual role in liver disease, ferroptosis also offers a promising strategy for precise cancer therapy. Ferroptosis regulators are beneficial in maintaining cellular homeostasis and tissue health, have shown efficacy in treating diseases of the hepatic system. However, the mechanisms of action and molecular regulatory pathways of ferroptosis in hepatocellular carcinoma (HCC) have not been fully elucidated. Therefore, deciphering the role of ferroptosis and its mechanisms in HCC progression is crucial for treating the disease. In this review, we introduce the morphological features and biochemical functions of ferroptosis, outline the molecular regulatory pathways of ferroptosis, and highlights the therapeutic potential of ferroptosis inhibitors and modulators to target it in HCC.

Fructose-1,6-bisphosphatase 1 dephosphorylates and inhibits TERT for tumor suppression

Telomere dysfunction is intricately linked to the aging process and stands out as a prominent cancer hallmark. Here we demonstrate that telomerase activity is differentially regulated in cancer and normal cells depending on the expression status of fructose-1,6-bisphosphatase 1 (FBP1). In FBP1-expressing cells, FBP1 directly interacts with and dephosphorylates telomerase reverse transcriptase (TERT) at Ser227. Dephosphorylated TERT fails to translocate into the nucleus, leading to the inhibition of telomerase activity, reduction in telomere lengths, enhanced senescence and suppressed tumor cell proliferation and growth in mice. Lipid nanoparticle-mediated delivery of FBP1 mRNA inhibits liver tumor growth. Additionally, FBP1 expression levels inversely correlate with TERT pSer227 levels in renal and hepatocellular carcinoma specimens and with poor prognosis of the patients. These findings demonstrate that FBP1 governs cell immortality through its protein phosphatase activity and uncover a unique telomerase regulation in tumor cells attributed to the downregulation or deficiency of FBP1 expression.

Tumor Metabolism: A New Field for the Treatment of Glioma

The clinical treatment of glioma remains relatively immature. Commonly used clinical treatments for gliomas are surgery combined with chemotherapy and radiotherapy, but there is a problem of drug resistance. In addition, immunotherapy and targeted therapies also suffer from the problem of immune evasion. The advent of metabolic therapy holds immense potential for advancing more efficacious and tolerable therapies against this aggressive disease. Metabolic therapy alters the metabolic processes of tumor cells at the molecular level to inhibit tumor growth and spread, and lead to better outcomes for patients with glioma that are insensitive to conventional treatments. Moreover, compared with conventional therapy, it has less impact on normal cells, less toxicity and side effects, and higher safety. The objective of this review is to examine the changes in metabolic characteristics throughout the development of glioma, enumerate the current methodologies employed for studying tumor metabolism, and highlight the metabolic reprogramming pathways of glioma along with their potential molecular mechanisms. Importantly, it seeks to elucidate potential metabolic targets for glioblastoma (GBM) therapy and summarize effective combination treatment strategies based on various studies.

The Anticancer Activity of Monosaccharides: Perspectives and Outlooks

A major hallmark of cancer is the reprogramming of cellular metabolism from oxidative phosphorylation (OXPHOS) to glycolysis, a phenomenon known as the Warburg effect. To sustain high rates of glycolysis, cancer cells overexpress GLUT transporters and glycolytic enzymes, allowing for the enhanced uptake and consumption of glucose. The Warburg effect may be exploited in the treatment of cancer; certain epimers and derivatives of glucose can enter cancer cells and inhibit glycolytic enzymes, stunting metabolism and causing cell death. These include common dietary monosaccharides (ᴅ-mannose, ᴅ-galactose, ᴅ-glucosamine, ʟ-fucose), as well as some rare monosaccharides (xylitol, ᴅ-allose, ʟ-sorbose, ʟ-rhamnose). This article reviews the literature on these sugars in in vitro and in vivo models of cancer, discussing their mechanisms of cytotoxicity. In addition to this, the anticancer potential of some synthetically modified monosaccharides, such as 2-deoxy-ᴅ-glucose and its acetylated and halogenated derivatives, is reviewed. Further, this article reviews how certain monosaccharides can be used in combination with anticancer drugs to potentiate conventional chemotherapies and to help overcome chemoresistance. Finally, the limitations of administering two separate agents, a sugar and a chemotherapeutic drug, are discussed. The potential of the glycoconjugation of classical or repurposed chemotherapy drugs as a solution to these limitations is reviewed.

PRMT6-mediated ADMA promotes p62 phase separation to form a negative feedback loop in ferroptosis

Purpose: Due to intrinsic defensive response, ferroptosis-activating targeted therapy fails to achieve satisfactory clinical benefits. Though p62-Keap1-Nrf2 axis is activated to form a negative feedback loop during ferroptosis induction, how p62 is activated remains largely unknown. Methods: MTS assay was applied to measure cell growth. Lipid ROS was detected with C11-BODIPY reagent by flow cytometer. Quantitative real-time PCR (qPCR) and western blotting were performed to determine mRNA and protein level. Immunofluorescence (IF) was performed to examine the distribution of proteins. Fluorescence recovery after photobleaching (FRAP) was adopted to evaluate p62 phase separation. Immunoprecipitation (IP), co-IP and Proximal ligation assay (PLA) were performed to detected protein posttranslational modifications and protein-protein interactions. Tumor xenograft model was employed to inspect in vivo growth of pancreatic cancer cells. Results: Upon ferroptosis induction, Nuclear Factor E2 Related Factor 2 (Nrf2) protein and its downstream genes such as HMOX1 and NQO1 were upregulated. Knockdown of p62 significantly reversed Nrf2 upregulation and Keap1 decrease after ferroptosis induction. Knockdown of either p62 or Nrf2 remarkably sensitized ferroptosis induction. Due to augmented p62 phase separation, formation of p62 bodies were increased to recruit Keap1 after ferroptosis induction. Protein arginine methyltransferase 6 (PRMT6) mediated asymmetric dimethylarginine (ADMA) of p62 to increase its oligomerization, promoting p62 phase separation and p62 body formation. Knockdown of p62 or PRMT6 notably sensitized pancreatic cancer cells to ferroptosis both in vitro and in vivo through suppressing Nrf2 signaling. Conclusion: During ferroptosis induction, PRMT6 mediated p62 ADMA to promote its phase separation, sequestering Keap1 to activate Nrf2 signaling and inhibit ferroptosis. Therefore, targeting PRMT6-mediated p62 ADMA could be a new option to sensitize ferroptosis for cancer treatment.

KHK-A promotes fructose-dependent colorectal cancer liver metastasis by facilitating the phosphorylation and translocation of PKM2

Excessive fructose diet is closely associated with colorectal cancer (CRC) progression. Nevertheless, fructose's specific function and precise mechanism in colorectal cancer liver metastasis (CRLM) is rarely known. Here, this study reported that the fructose absorbed by primary colorectal cancer could accelerate CRLM, and the expression of KHK-A, not KHK-C, in liver metastasis was higher than in paired primary tumors. Furthermore, KHK-A facilitated fructose-dependent CRLM in vitro and in vivo by phosphorylating PKM2 at Ser37. PKM2 phosphorylated by KHK-A inhibited its tetramer formation and pyruvic acid kinase activity but promoted the nuclear accumulation of PKM2. EMT and aerobic glycolysis activated by nuclear PKM2 enhance CRC cells' migration ability and anoikis resistance during CRLM progression. TEPP-46 treatment, targeting the phosphorylation of PKM2, inhibited the pro-metastatic effect of KHK-A. Besides, c-myc activated by nuclear PKM2 promotes alternative splicing of KHK-A, forming a positive feedback loop.

Base editing of the mutated TERT promoter inhibits liver tumor growth

BACKGROUND AND AIMS

Base editing has shown great potential for treating human diseases with mutated genes. However, its potential for treating HCC has not yet been explored.

APPROACH AND RESULTS

We employed adenine base editors (ABEs) to correct a telomerase reverse transcriptase ( TERT ) promoter mutation, which frequently occurs in various human cancers, including HCC. The mutated TERT promoter -124 C>T is corrected to -124 C by a single guide (sg) RNA-guided and deactivated Campylobacter jejuni Cas9 (CjCas9)-fused adenine base editor (CjABE). This edit impairs the binding of the E-twenty six/ternary complex factor transcription factor family, including E-twenty six-1 and GABPA, to the TERT promoter, leading to suppressed TERT promoter and telomerase activity, decreased TERT expression and cell proliferation, and increased cell senescence. Importantly, injection of adeno-associated viruses expressing sgRNA-guided CjABE or employment of lipid nanoparticle-mediated delivery of CjABE mRNA and sgRNA inhibits the growth of liver tumors harboring TERT promoter mutations.

CONCLUSIONS

These findings demonstrate that a sgRNA-guided CjABE efficiently converts the mutated TERT promoter -124 C>T to -124 C in HCC cells and underscore the potential to treat HCC by the base editing-mediated correction of TERT promoter mutations.

Metabolic heterogeneity in tumor microenvironment - A novel landmark for immunotherapy

The surrounding non-cancer cells and tumor cells that make up the tumor microenvironment (TME) have various metabolic rhythms. TME metabolic heterogeneity is influenced by the intricate network of metabolic control within and between cells. DNA, protein, transport, and microbial levels are important regulators of TME metabolic homeostasis. The effectiveness of immunotherapy is also closely correlated with alterations in TME metabolism. The response of a tumor patient to immunotherapy is influenced by a variety of variables, including intracellular metabolic reprogramming, metabolic interaction between cells, ecological changes within and between tumors, and general dietary preferences. Although immunotherapy and targeted therapy have made great strides, their use in the accurate identification and treatment of tumors still has several limitations. The function of TME metabolic heterogeneity in tumor immunotherapy is summarized in this article. It focuses on how metabolic heterogeneity develops and is regulated as a tumor progresses, the precise molecular mechanisms and potential clinical significance of imbalances in intracellular metabolic homeostasis and intercellular metabolic coupling and interaction, as well as the benefits and drawbacks of targeted metabolism used in conjunction with immunotherapy. This offers insightful knowledge and important implications for individualized tumor patient diagnosis and treatment plans in the future.

Ketohexokinase-A deficiency attenuates the proliferation via reducing β-catenin in gastric cancer cells

Overconsumption of fructose is closely related to cancer. Ketohexokinase (KHK) catalyzes the conversion from fructose to fructose-1-phosphate (F1P), which is the first and committed step of fructose metabolism. Recently, aberrant KHK activation has been identified in multiple malignancies. However, the roles of KHK in gastric cancer (GC) cells are largely unclear. Herein, we reveal that the expression of ketohexokinase-A (KHK-A), one alternatively spliced KHK isoform that possesses low affinity for fructose, was markedly increased in GC cells. Depletion of endogenous KHK-A expression using lentiviruses encoding short hairpin RNAs (shRNAs) or pharmaceutical disruption of KHK-A activity using KHK-IN-1 hydrochloride in GC NCI-N87 and HGC-27 cells inhibited the proliferation in vitro and in vivo. Additionally, the mitochondrial respiration in the GC cells with KHK-A deficiency compared with the control cells was significantly impaired. One commercially-available antibody array was used to explore the effects of KHK-A knockdown on signaling pathways, showing that β-catenin was remarkably reduced in the KHK-A deficient GC cells compared with the control ones. Pharmaceutical reduction in β-catenin levels slowed down the proliferation of GC cells. These data uncover that KHK-A promotes the proliferation in GC cells, indicating that this enzyme might be a promising therapeutical target for GC treatment.

The Role of Oxidative Stress in Tumorigenesis and Progression

Oxidative stress refers to the imbalance between the production of reactive oxygen species (ROS) and the endogenous antioxidant defense system. Its involvement in cell senescence, apoptosis, and series diseases has been demonstrated. Advances in carcinogenic research have revealed oxidative stress as a pivotal pathophysiological pathway in tumorigenesis and to be involved in lung cancer, glioma, hepatocellular carcinoma, leukemia, and so on. This review combs the effects of oxidative stress on tumorigenesis on each phase and cell fate determination, and three features are discussed. Oxidative stress takes part in the processes ranging from tumorigenesis to tumor death via series pathways and processes like mitochondrial stress, endoplasmic reticulum stress, and ferroptosis. It can affect cell fate by engaging in the complex relationships between senescence, death, and cancer. The influence of oxidative stress on tumorigenesis and progression is a multi-stage interlaced process that includes two aspects of promotion and inhibition, with mitochondria as the core of regulation. A deeper and more comprehensive understanding of the effects of oxidative stress on tumorigenesis is conducive to exploring more tumor therapies.

MTMR7 suppresses the phenotypic switching of vascular smooth muscle cell and vascular intimal hyperplasia after injury via regulating p62/mTORC1-mediated glucose metabolism

BACKGROUND AND AIMS

Myotubularin-related protein 7 (MTMR7) suppresses proliferation in various cell types and is associated with cardiovascular and cerebrovascular diseases. However, whether MTMR7 regulates vascular smooth muscle cell (VSMC) and vascular intimal hyperplasia remains unclear. We explored the role of MTMR7 in phenotypic switching of VSMC and vascular intimal hyperplasia after injury.

METHODS AND RESULTS

MTMR7 expression was significantly downregulated in injured arteries. Compared to wild type (WT) mice, Mtmr7-transgenic (Mtmr7-Tg) mice showed reduced intima/media ratio, decreased percentage of Ki-67-positive cells within neointima, and increased Calponin expression in injured artery. In vitro, upregulating MTMR7 by Len-Mtmr7 transfection inhibited platelet derived growth factor (PDGF)-BB-induced proliferation, migration of VSMC and reversed PDGF-BB-induced decrease in expression of Calponin and SM-MHC. Microarray, single cell sequence, and other bioinformatics analysis revealed that MTMR7 is highly related to glucose metabolism and mammalian target of rapamycin complex 1 (mTORC1). Further experiments confirmed that MTMR7 markedly repressed glycolysis and mTORC1 activity in PDGF-BB-challenged VSMC in vitro. Restoring mTORC1 activity abolished MTMR7-mediated suppression of glycolysis, phenotypic shift in VSMC in vitro and protection against vascular intimal hyperplasia in vivo. Furthermore, upregulating MTMR7 in vitro led to dephosphorylation and dissociation of p62 from mTORC1 in VSMC. External expression of p62 in vitro also abrogated the inhibitory effects of MTMR7 on glycolysis and phenotypic switching in PDGF-BB-stimulated VSMC.

CONCLUSIONS

Our study demonstrates that MTMR7 inhibits injury-induced vascular intimal hyperplasia and phenotypic switching of VSMC. Mechanistically, the beneficial effects of MTMR7 are conducted via suppressing p62/mTORC1-mediated glycolysis.

VHL suppresses autophagy and tumor growth through PHD1-dependent Beclin1 hydroxylation

The Von Hippel-Lindau (VHL) protein, which is frequently mutated in clear-cell renal cell carcinoma (ccRCC), is a master regulator of hypoxia-inducible factor (HIF) that is involved in oxidative stresses. However, whether VHL possesses HIF-independent tumor-suppressing activity remains largely unclear. Here, we demonstrate that VHL suppresses nutrient stress-induced autophagy, and its deficiency in sporadic ccRCC specimens is linked to substantially elevated levels of autophagy and correlates with poorer patient prognosis. Mechanistically, VHL directly binds to the autophagy regulator Beclin1, after its PHD1-mediated hydroxylation on Pro54. This binding inhibits the association of Beclin1-VPS34 complexes with ATG14L, thereby inhibiting autophagy initiation in response to nutrient deficiency. Expression of non-hydroxylatable Beclin1 P54A abrogates VHL-mediated autophagy inhibition and significantly reduces the tumor-suppressing effect of VHL. In addition, Beclin1 P54-OH levels are inversely correlated with autophagy levels in wild-type VHL-expressing human ccRCC specimens, and with poor patient prognosis. Furthermore, combined treatment of VHL-deficient mouse tumors with autophagy inhibitors and HIF2α inhibitors suppresses tumor growth. These findings reveal an unexpected mechanism by which VHL suppresses tumor growth, and suggest a potential treatment for ccRCC through combined inhibition of both autophagy and HIF2α.

UBC9 stabilizes PFKFB3 to promote aerobic glycolysis and proliferation of glioblastoma cells

Cancer cells prefer to utilizing aerobic glycolysis to generate energy and anabolic metabolic intermediates for cell growth. However, whether the activities of glycolytic enzymes can be regulated by specific posttranslational modifications, such as SUMOylation, in response to oncogenic signallings, thereby promoting the Warburg effect, remain largely unclear. Here, we demonstrate that phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), a key glycolytic enzyme, interacts with SUMO-conjugating enzyme UBC9 and is SUMOylated at K302 in glioblastoma cells. Expression of UBC9, which competitively prevents the binding of ubiquitin E3 ligase APC/C to PFKFB3 and subsequent PFKFB3 polyubiquitination, increases PFKFB3 stability and expression. Importantly, EGFR activation increases the interaction between UBC9 and PFKFB3, leading to increased SUMOylation and expression of PFKFB3. This increase is blocked by inhibition of EGFR-induced AKT activation whereas expression of activate AKT by itself was sufficient to recapitulate EGF-induced effect. Knockout of PFKFB3 expression decreases EGF-enhanced lactate production and GBM cell proliferation and this decrease was fully rescued by reconstituted expression of WT PFKFB3 whereas PFKFB3 K302R mutant expression abrogates EGF- and UBC9-regulated lactate production and GBM cell proliferation. These findings reveal a previously unknown mechanism underlying the regulation of the Warburg effect through the EGFR activation-induced and UBC9-mediated SUMOylation and stabilization of PFKFB3.

Fructose-1,6-bisphosphatase 1 suppresses PPARα-mediated gene transcription and non-small-cell lung cancer progression

Rapidly growing tumors often encounter energy stress, such as glutamine deficiency. However, how normal and tumor cells differentially respond to glutamine deficiency remains largely unclear. Here, we demonstrate that glutamine deprivation activates PERK, which phosphorylates FBP1 at S170 and induces nuclear accumulation of FBP1. Nuclear FBP1 inhibits PPARα-mediated β-oxidation gene transcription in normal lung epithelial cells. In contrast, highly expressed OGT in non-small cell lung cancer (NSCLC) cells promotes FBP1 O-GlcNAcylation, which abrogates FBP1 phosphorylation and enhances β-oxidation gene transcription to support cell proliferation under glutamine deficiency. In addition, FBP1 pS170 is negatively correlated with OGT expression in human NSCLC specimens, and low expression of FBP1 pS170 is associated with poor prognosis in NSCLC patients. These findings highlight the differential regulation of FBP1 in normal and NSCLC cells under glutamine deprivation and underscore the potential to target nuclear FBP1 for NSCLC treatment.

Glycolytic enzyme HK2 promotes PD-L1 expression and breast cancer cell immune evasion

Immune therapies targeting the PD-1/PD-L1 pathway have been employed in the treatment of breast cancer, which requires aerobic glycolysis to sustain breast cancer cells growth. However, whether PD-L1 expression is regulated by glycolysis in breast cancer cells remains to be further elucidated. Here, we demonstrate that glycolytic enzyme hexokinase 2 (HK2) plays a crucial role in upregulating PD-L1 expression. Under high glucose conditions, HK2 acts as a protein kinase and phosphorylates IκBα at T291 in breast cancer cells, leading to the rapid degradation of IκBα and activation of NF-κB, which enters the nucleus and promotes PD-L1 expression. Immunohistochemistry staining of human breast cancer specimens and bioinformatics analyses reveals a positive correlation between HK2 and PD-L1 expression levels, which are inversely correlated with immune cell infiltration and survival time of breast cancer patients. These findings uncover the intrinsic and instrumental connection between aerobic glycolysis and PD-L1 expression-mediated tumor cell immune evasion and underscore the potential to target the protein kinase activity of HK2 for breast cancer treatment.

Creatine kinase brain-type regulates BCAR1 phosphorylation to facilitate DNA damage repair

Creatine kinase (CK) is an essential metabolic enzyme mediating creatine/phosphocreatine interconversion and shuttle to replenish ATP for energy needs. Ablation of CK causes a deficiency in energy supply that eventually results in reduced muscle burst activity and neurological disorders in mice. Besides the well-established role of CK in energy-buffering, the mechanism underlying the non-metabolic function of CK is poorly understood. Here we demonstrate that creatine kinase brain-type (CKB) may function as a protein kinase to regulate BCAR1 Y327 phosphorylation that enhances the association between BCAR1 and RBBP4. Then the complex of BCAR1 and RPPB4 binds to the promoter region of DNA damage repair gene RAD51 and activates its transcription by modulating histone H4K16 acetylation to ultimately promote DNA damage repair. These findings reveal the possible role of CKB independently of its metabolic function and depict the potential pathway of CKB-BCAR1-RBBP4 operating in DNA damage repair.

Creatine kinase B suppresses ferroptosis by phosphorylating GPX4 through a moonlighting function

Activation of receptor protein kinases is prevalent in various cancers with unknown impact on ferroptosis. Here we demonstrated that AKT activated by insulin-like growth factor 1 receptor signalling phosphorylates creatine kinase B (CKB) T133, reduces metabolic activity of CKB and increases CKB binding to glutathione peroxidase 4 (GPX4). Importantly, CKB acts as a protein kinase and phosphorylates GPX4 S104. This phosphorylation prevents HSC70 binding to GPX4, thereby abrogating the GPX4 degradation regulated by chaperone-mediated autophagy, alleviating ferroptosis and promoting tumour growth in mice. In addition, the levels of GPX4 are positively correlated with the phosphorylation levels of CKB T133 and GPX4 S104 in human hepatocellular carcinoma specimens and associated with poor prognosis of patients with hepatocellular carcinoma. These findings reveal a critical mechanism by which tumour cells counteract ferroptosis by non-metabolic function of CKB-enhanced GPX4 stability and underscore the potential to target the protein kinase activity of CKB for cancer treatment.

Rare sugar L-sorbose exerts antitumor activity by impairing glucose metabolism

Rare sugars are monosaccharides with low natural abundance. They are structural isomers of dietary sugars, but hardly be metabolized. Here, we report that rare sugar L-sorbose induces apoptosis in various cancer cells. As a C-3 epimer of D-fructose, L-sorbose is internalized via the transporter GLUT5 and phosphorylated by ketohexokinase (KHK) to produce L-sorbose-1-phosphate (S-1-P). Cellular S-1-P inactivates the glycolytic enzyme hexokinase resulting in attenuated glycolysis. Consequently, mitochondrial function is impaired and reactive oxygen species are produced. Moreover, L-sorbose downregulates the transcription of KHK-A, a splicing variant of KHK. Since KHK-A is a positive inducer of antioxidation genes, the antioxidant defense mechanism in cancer cells can be attenuated by L-sorbose-treatment. Thus, L-sorbose performs multiple anticancer activities to induce cell apoptosis. In mouse xenograft models, L-sorbose enhances the effect of tumor chemotherapy in combination with other anticancer drugs. These results demonstrate L-sorbose as an attractive therapeutic reagent for cancer treatment.

Hexokinases in cancer and other pathologies

Glucose metabolism is indispensable for cell growth and survival. Hexokinases play pivotal roles in glucose metabolism through canonical functions of hexokinases as well as in immune response, cell stemness, autophagy, and other cellular activities through noncanonical functions. The aberrant regulation of hexokinases contributes to the development and progression of pathologies, including cancer and immune diseases.

p62/SQSTM1 in liver diseases: the usual suspect with multifarious identities

p62/Sequestosome-1 (SQSTM1) is a selective autophagy receptor that recruits and delivers intracellular substrates for bulk clearance through the autophagy lysosomal pathway. Interestingly, p62 also serves as a signaling scaffold to participate in the regulation of multiple physiological processes, including oxidative stress response, metabolism, inflammation, and programmed cell death. Perturbation of p62 activity has been frequently found to be associated with the pathogenesis of many liver diseases. p62 has been identified as a critical component of protein aggregates in the forms of Mallory-Denk bodies (MDBs) or intracellular hyaline bodies (IHBs), which are known to be frequently detected in biopsy samples from alcoholic steatohepatitis (ASH), non-alcoholic steatohepatitis (NASH), and hepatocellular carcinoma (HCC) patients. Importantly, abundance of these p62 inclusion bodies is increasingly recognized as a biomarker for NASH and HCC. Although the level of p62 bodies seems to predict the progression and prognosis of these liver diseases, understanding of the underlying mechanisms by which p62 regulates and contributes to the development and progression of these diseases remains incomplete. In this review, we will focus on the function and regulation of p62, and its pathophysiological roles in the liver, by critically reviewing the findings from preclinical models that recapitulate the pathogenesis and manifestation of these liver diseases in humans. In addition, we will also explore the suitability of p62 as a predictive biomarker and a potential therapeutic target for the treatment of liver diseases, including NASH and HCC, as well as recent development of small-molecule compounds for targeting the p62 signaling axis.

Nucleus-exported CLOCK acetylates PRPS to promote de novo nucleotide synthesis and liver tumour growth

Impairment of the circadian clock is linked to cancer development. However, whether the circadian clock is modulated by oncogenic receptor tyrosine kinases remains unclear. Here we demonstrated that receptor tyrosine kinase activation promotes CK2-mediated CLOCK S106 phosphorylation and subsequent disassembly of the CLOCK-BMAL1 dimer and suppression of the downstream gene expression in hepatocellular carcinoma (HCC) cells. In addition, CLOCK S106 phosphorylation exposes its nuclear export signal to bind Exportin1 for nuclear exportation. Cytosolic CLOCK acetylates PRPS1/2 K29 and blocks HSC70-mediated and lysosome-dependent PRPS1/2 degradation. Stabilized PRPS1/2 promote de novo nucleotide synthesis and HCC cell proliferation and liver tumour growth. Furthermore, CLOCK S106 phosphorylation and PRPS1/2 K29 acetylation are positively correlated in human HCC specimens and with HCC poor prognosis. These findings delineate a critical mechanism by which oncogenic signalling inhibits canonical CLOCK transcriptional activity and simultaneously confers CLOCK with instrumental moonlighting functions to promote nucleotide synthesis and tumour growth.

Multi-Omics Approach Reveals Redox Homeostasis Reprogramming in Early-Stage Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is a malignant tumor originating from proximal tubular epithelial cells, and despite extensive research efforts, its redox homeostasis characteristics and protein S-nitrosylation (or S-nitrosation) (SNO) modification remain largely undefined. This serves as a reminder that the aforementioned features demand a comprehensive inspection. We collected tumor samples and paracancerous normal samples from five patients with early-stage ccRCC (T1N0M0) for proteomic, SNO-proteome, and redox-targeted metabolic analyses. The localization and functional properties of SNO proteins in ccRCC tumors and paracancerous normal tissues were elucidated for the first time. Several highly useful ccRCC-associated SNO proteins were further identified. Metabolic reprogramming, redox homeostasis reprogramming, and tumorigenic alterations are the three major characteristics of early-stage ccRCC. Peroxidative damage caused by rapid proliferation coupled with an increased redox buffering capacity and the antioxidant pool is a major mode of redox homeostasis reprogramming. NADPH and NADP⁺, which were identified from redox species, are both effective biomarkers and promising therapeutic targets. According to our findings, SNO protein signatures and redox homeostasis reprogramming are valuable for understanding the pathogenesis of ccRCC and identifying novel topics that should be seriously considered for the diagnosis and precise therapy of ccRCC.

TLR3 serves as a novel diagnostic and prognostic biomarker and is closely correlated with immune microenvironment in three types of cancer

Background: Toll-like receptor 3 (TLR3) plays an important role in both innate and adaptive immunity, but the prognostic value of TLR3 in heterogeneous tumors and the correlations between TLR3 expression and immune infiltration of heterogeneous tumors remain unclear. Methods: We investigated the expression of TLR3 in a variety of tumors and focused on the diagnostic and prognostic values of TLR3 in kidney renal clear cell carcinoma (KIRC), pancreatic adenocarcinoma (PAAD) and brain lower grade glioma (LGG) by GEPIA, DriverDBv3, UALCAN, TIMER, LinkedOmics, STRING, GeneMANIA and FunRich, as well as the possible mechanisms of TLR3 affecting tumor prognosis were discussed. Additionally, real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) was used to validate TLR3 expression in early KIRC. We also compared the expression of TLR3 in the plasma of early KIRC patients and normal controls by enzyme linked immunosorbent assay (ELISA). Results: TLR3 expression was significantly different in multiple tumors compared with paracancerous nontumor tissues. Elevated expression of TLR3 contributed to the prolonged survival outcome in KIRC patients. Suppressed expression of TLR3 contributed to the prolonged survival outcome in LGG and PAAD patients. Moreover, TLR3 was significantly elevated in stage1, grade1 and N0 of KIRC. The expression and function of TLR3 in KIRC, LGG and PAAD were closely related to tumor immune microenvironment. TRAF6 was a key gene in the interactions between TLR3 and its interacting genes. Finally, the results of RT-qPCR and ELISA indicated that TLR3 expression levels were significantly raised in renal tissue and plasma of early KIRC patients. Conclusion: TLR3 has the potential to be a diagnostic biomarker of KIRC, LGG and PAAD as well as a biomarker for evaluating the prognosis of KIRC, LGG and PAAD, particularly for the early diagnosis of KIRC. TLR3 affects tumors mainly by acting on the immune microenvironment of KIRC, LGG and PAAD. These findings could lead to new insights into the immunotherapeutic targets for KIRC, LGG, and PAAD.

Fructose-1,6-bisphosphatase 1 functions as a protein phosphatase to dephosphorylate histone H3 and suppresses PPARα-regulated gene transcription and tumour growth

Tumour cells exhibit greater metabolic plasticity than normal cells and possess selective advantages for survival and proliferation with unclearly defined mechanisms. Here we demonstrate that glucose deprivation in normal hepatocytes induces PERK-mediated fructose-1,6-bisphosphatase 1 (FBP1) S170 phosphorylation, which converts the FBP1 tetramer to monomers and exposes its nuclear localization signal for nuclear translocation. Importantly, nuclear FBP1 binds PPARα and functions as a protein phosphatase that dephosphorylates histone H3T11 and suppresses PPARα-mediated β-oxidation gene expression. In contrast, FBP1 S124 is O-GlcNAcylated by overexpressed O-linked N-acetylglucosamine transferase in hepatocellular carcinoma cells, leading to inhibition of FBP1 S170 phosphorylation and enhancement of β-oxidation for tumour growth. In addition, FBP1 S170 phosphorylation inversely correlates with β-oxidation gene expression in hepatocellular carcinoma specimens and patient survival duration. These findings highlight the differential role of FBP1 in gene regulation in normal and tumour cells through direct chromatin modulation and underscore the inactivation of its protein phosphatase function in tumour growth.

Cobalt chloride has beneficial effects across species through a hormetic mechanism

Severe oxygen and iron deficiencies have evolutionarily conserved detrimental effects, leading to pathologies in mammals and developmental arrest as well as neuromuscular degeneration in the nematode Caenorhabditis elegans. Yet, similar to the beneficial effects of mild hypoxia, non-toxic levels of iron depletion, achieved with the iron chelator bipyridine or through frataxin silencing, extend C. elegans lifespan through hypoxia-like induction of mitophagy. While the positive health outcomes of hypoxia preconditioning are evident, its practical application is rather challenging. Here, we thus test the potential beneficial effects of non-toxic, preconditioning interventions acting on iron instead of oxygen availability. We find that limiting iron availability through the iron competing agent cobalt chloride has evolutionarily conserved dose-dependent beneficial effects: while high doses of cobalt chloride have toxic effects in mammalian cells, iPS-derived neurospheres, and in C. elegans, sub-lethal doses protect against hypoxia- or cobalt chloride-induced death in mammalian cells and extend lifespan and delay age-associated neuromuscular alterations in C. elegans. The beneficial effects of cobalt chloride are accompanied by the activation of protective mitochondrial stress response pathways.

Aerobic glycolysis promotes tumor immune evasion by hexokinase2-mediated phosphorylation of IκBα

High expression of PD-L1 in tumor cells contributes to tumor immune evasion. However, whether PD-L1 expression in tumor cells is regulated by the availability of nutrients is unknown. Here, we show that in human glioblastoma cells, high glucose promotes hexokinase (HK) 2 dissociation from mitochondria and its subsequent binding and phosphorylation of IκBα at T291. This leads to increased interaction between IκBα and μ-calpain protease and subsequent μ-calpain-mediated IκBα degradation and NF-κB activation-dependent transcriptional upregulation of PD-L1 expression. Expression of IκBα T291A in glioblastoma cells blocked high glucose-induced PD-L1 expression and promoted CD8⁺ T cell activation and infiltration into the tumor tissue, reducing brain tumor growth. Combined treatment with an HK inhibitor and an anti-PD-1 antibody eliminates tumor immune evasion and remarkably enhances the anti-tumor effect of immune checkpoint blockade. These findings elucidate a novel mechanism underlying the upregulation of PD-L1 expression mediated by aerobic glycolysis and underscore the roles of HK2 as a glucose sensor and a protein kinase in regulation of tumor immune evasion.

AMPK and NRF2: Interactive players in the same team for cellular homeostasis?

NRF2 (Nuclear factor E2 p45-related factor 2) is a stress responsive transcription factor lending cells resilience against oxidative, xenobiotic, and also nutrient or proteotoxic insults. AMPK (AMP-activated kinase), considered as prime regulator of cellular energy homeostasis, not only tunes metabolism to provide the cell at any time with sufficient ATP or building blocks, but also controls redox balance and inflammation. Due to observed overlapping cellular responses upon AMPK or NRF2 activation and common stressors impinging on both AMPK and NRF2 signaling, it is plausible to assume that AMPK and NRF2 signaling may interdepend and cooperate to readjust cellular homeostasis. After a short introduction of the two players this narrative review paints the current picture on how AMPK and NRF2 signaling might interact on the molecular level, and highlights their possible crosstalk in selected examples of pathophysiology or bioactivity of drugs and phytochemicals.

A non-metabolic function of hexokinase 2 in small cell lung cancer: promotes cancer cell stemness by increasing USP11-mediated CD133 stability

Background

Maintenance of cancer stem‐like cell (CSC) stemness supported by aberrantly regulated cancer cell metabolism is critical for CSC self‐renewal and tumor progression. As a key glycolytic enzyme, hexokinase 2 (HK2) plays an instrumental role in aerobic glycolysis and tumor progression. However, whether HK2 directly contribute to CSC stemness maintenance in small cell lung cancer (SCLC) is largely unclear. In this study, we aimed to investgate whether HK2 independent of its glycolytic activity is directly involved in stemness maintenance of CSC in SCLC.

Methods

Immunoblotting analyses were conducted to determine the expression of HK2 in SCLC CSCs and their differentiated counterparts. CSC‐like properties and tumorigenesis of SCLC cells with or without HK2 depletion or overexpression were examined by sphere formation assay and xenograft mouse model. Immunoprecipitation and mass spectrometry analyses were performed to identify the binding proteins of CD133. The expression levels of CD133‐associated and CSC‐relevant proteins were evaluated by immunoblotting, immunoprecipitation, immunofluorescence, and immunohistochemistry assay. RNA expression levels of Nanog, POU5F1, Lin28, HK2, Prominin‐1 were analyzed through quantitative reverse transcription PCR. Polyubiquitination of CD133 was examined by in vitro or in vivo ubiquitination assay. CD133⁺ cells were sorted by flow cytometry using an anti‐CD133 antibody.

Results

We demonstrated that HK2 expression was much higher in CSCs of SCLC than in their differentiated counterparts. HK2 depletion inhibited CSC stemness and promoted CSC differentiation. Mechanistically, non‐mitochondrial HK2 directly interacted with CD133 and enhanced CD133 expression without affecting CD133 mRNA levels. The interaction of HK2 and CD133 promoted the binding of the deubiquitinase ubiquitin‐specific protease 11 (USP11) to CD133, thereby inhibiting CD133 polyubiquitylation and degradation. HK2‐mediated upregulation of CD133 expression enhanced the expression of cell renewal regulators, SCLC cell stemness, and tumor growth in mice. In addition, HK2 expression was positively correlated with CD133 expression in human SCLC specimens, and their expression levels were associated with poor prognosis of SCLC patients.

Conclusions

These results revealed a critical non‐metabolic function of HK2 in promotion of cancer cell stemness. Our findings provided new insights into the multifaceted roles of HK2 in tumor development.

The Combination of Niacinamide, Vitamin C, and PDRN Mitigates Melanogenesis by Modulating Nicotinamide Nucleotide Transhydrogenase

Nicotinamide nucleotide transhydrogenase (NNT) is involved in decreasing melanogenesis through tyrosinase degradation induced by cellular redox changes. Nicotinamide is a component of coenzymes, such as NAD+, NADH, NADP+, and NADPH, and its levels are modulated by NNT. Vitamin C and polydeoxyribonucleotide (PDRN) are also known to decrease skin pigmentation. We evaluated whether a mixture of nicotinamide, vitamin C, and PDRN (NVP-mix) decreased melanogenesis by modulating mitochondrial oxidative stress and NNT expression in UV-B-irradiated animals and in an in vitro model of melanocytes treated with conditioned media (CM) from UV-B-irradiated keratinocytes. The expression of NNT, GSH/GSSG, and NADPH/NADP+ in UV-B-irradiated animal skin was significantly decreased by UV-B radiation but increased by NVP-mix treatment. The expression of NNT, GSH/GSSG, and NADPH/NADP+ ratios decreased in melanocytes after CM treatment, although they increased after NVP-mix administration. In NNT-silenced melanocytes, the GSH/GSSG and NADPH/NADP+ ratios were further decreased by CM compared with normal melanocytes. NVP-mix decreased melanogenesis signals, such as MC1R, MITF, TYRP1, and TYRP2, and decreased melanosome transfer-related signals, such as RAB32 and RAB27A, in UV-B-irradiated animal skin. NVP-mix also decreased MC1R, MITF, TYRP1, TYRP2, RAB32, and RAB27A in melanocytes treated with CM from UV-irradiated keratinocytes. The expression of MC1R and MITF in melanocytes after CM treatment was unchanged by NNT silencing. However, the expression of TYRP1, TYRP2, RAB32, and RAB27A increased in NNT-silenced melanocytes after CM treatment. NVP-mix also decreased tyrosinase activity and melanin content in UV-B-irradiated animal skin and CM-treated melanocytes. In conclusion, NVP-mix decreased mitochondrial oxidative stress by increasing NNT expression and decreased melanogenesis by decreasing MC1R/MITF, tyrosinase, TYRP1, and TYRP2.

p62-Nrf2 Regulatory Loop Mediates the Anti-Pulmonary Fibrosis Effect of Bergenin

Idiopathic pulmonary fibrosis (IPF) can severely disrupt lung function, leading to fatal consequences, and there is currently a lack of specific therapeutic drugs. Bergenin is an isocoumarin compound with lots of biological functions including antioxidant activity. This study evaluated the potential beneficial effects of bergenin on pulmonary fibrosis and investigated the possible mechanisms. We found that bergenin alleviated bleomycin-induced pulmonary fibrosis by relieving oxidative stress, reducing the deposition of the extracellular matrix (ECM) and inhibiting the formation of myofibroblasts. Furthermore, we showed that bergenin could induce phosphorylation and expression of p62 and activation of Nrf2, Nrf2 was required for bergenin-induced p62 upregulation, and p62 knockdown reduced bergenin-induced Nrf2 activity. More importantly, knockdown of Nrf2 or p62 could abrogate the antioxidant activity of bergenin and the inhibition effect of bergenin on TGF-β-induced ECM deposition and myofibroblast differentiation. Thereby, a regulatory loop is formed between p62 and Nrf2, which is an important target for bergenin aimed at treating pulmonary fibrosis.

SQSTM1 Expression in Hepatocellular Carcinoma and Relation to Tumor Recurrence After Radiofrequency Ablation

BACKGROUND/AIMS

Autophagy is a process that allows the degradation of detrimental components through the lysosome to maintain cellular homeostasis under variable stimuli. SQSTM1 is a key molecule involved in functional autophagy and is linked to different signaling pathways, oxidative responses, and inflammation. Dysregulation of autophagy is reported in a broad spectrum of diseases. Accumulation of SQSTM1 reflects impaired autophagy, which is related to carcinogenesis and progression of various tumors, including hepatocellular carcinoma (HCC). This study investigated SQSTM1 protein expression in HCC and its relation to the clinicopathological features and the likelihood of tumor recurrence after radiofrequency ablation (RFA).

METHODS

This study included 50 patients with cirrhotic HCC of Barcelona Clinic Liver Cancer stages 0/A-B eligible for RFA. Tumor and peritumor biopsies were obtained just prior to local ablation and assessed for tumor pathological grade and SQSTM1 expression by immunohistochemistry. Patients were followed for one year after achieving complete ablation to detect any tumor recurrence.

RESULTS

Serum alpha-fetoprotein level (U = 149.50, P = 0.027∗) and pathological grade of the tumor (χ² = 12.702, P = 0.002∗) associated significantly with the tumor response to RFA. SQSTM1 expression level was significantly increased in HCC compared to the adjacent peritumor cirrhotic liver tissues (Z = 5.927, P < 0.001∗). Significant direct relation was found between SQSTM1 expression level in HCC and the pathological grade of the tumor (H = 33.789, P < 0.001∗). On follow-up, tumor and peritumor SQSTM1 expression levels performed significantly as a potential predictor of the overall survival, but not the disease recurrence.

CONCLUSIONS

SQSTM1 expression could determine aggressive HCC, even with reasonable tumor size and number, and identify the subset of HCC patients with short overall survival and unfavorable prognosis. SQSTM1 expression could not predict post-RFA intrahepatic HCC recurrence. SQSTM1 may be a potential biomarker and target for the selection of HCC patients for future therapies.

Fructose Consumption and Hepatocellular Carcinoma Promotion

Hepatocellular carcinoma (HCC) accounts for 85% of primary liver cancer, the third most common cause of cancer-related deaths worldwide. Its incidence has been increasing in both men and women. In Western countries, high-calorie diets, mainly rich in carbohydrates such as fructose, represent a significant concern due to their repercussions on the population’s health. A high-fructose diet is related to the development of Metabolic-Associated Fatty Liver Disease (MAFLD), formerly named Non-Alcoholic Fatty Liver Disease (NAFLD), and the progression of HCC as it potentiates the lipogenic pathway and the accumulation of lipids. However, fructose metabolism seems to be different between the stages of the disease, carrying out a metabolic reprogramming to favor the proliferation, inflammation, and metastatic properties of cancer cells in HCC. This review focuses on a better understanding of fructose metabolism in both scenarios: MAFLD and HCC.

Dual Role of Reactive Oxygen Species and their Application in Cancer Therapy

Reactive oxygen species (ROS) play a dual role in the initiation, development, suppression, and treatment of cancer. Excess ROS can induce nuclear DNA, leading to cancer initiation. Not only that, but ROS also inhibit T cells and natural killer cells and promote the recruitment and M2 polarization of macrophages; consequently, cancer cells escape immune surveillance and immune defense. Furthermore, ROS promote tumor invasion and metastasis by triggering epithelial-mesenchymal transition in tumor cells. Interestingly, massive accumulation of ROS inhibits tumor growth in two ways: (1) by blocking cancer cell proliferation by suppressing the proliferation signaling pathway, cell cycle, and the biosynthesis of nucleotides and ATP and (2) by inducing cancer cell death via activating endoplasmic reticulum stress-, mitochondrial-, and P53- apoptotic pathways and the ferroptosis pathway. Unfortunately, cancer cells can adapt to ROS via a self-adaption system. This review highlighted the bidirectional regulation of ROS in cancer. The study further discussed the application of massively accumulated ROS in cancer treatment. Of note, the dual role of ROS in cancer and the self-adaptive ability of cancer cells should be taken into consideration for cancer prevention.

Fructose and fructose kinase in cancer and other pathologies

Fructose metabolism and fructose kinase KHK-C/A are key factors in the development of lipid oversynthesis-promoted metabolic disorders and cancer. Here, we summarize and discuss the current knowledge about the specific features of fructose metabolism and the distinct roles of KHK-C and KHK-A in metabolic liver diseases and their relevant metabolic disorders and cancer, and we highlight the specific protein kinase activity of KHK-A in tumor development. In addition, different approaches that have been used to inhibit KHK and the exploration of KHK inhibitors in clinical treatment are introduced.

Multiplexed proteomics of autophagy-deficient murine macrophages reveals enhanced antimicrobial immunity via the oxidative stress response

Defective autophagy is strongly associated with chronic inflammation. Loss-of-function of the core autophagy gene Atg16l1 increases risk for Crohn's disease in part by enhancing innate immunity through myeloid cells such as macrophages. However, autophagy is also recognized as a mechanism for clearance of certain intracellular pathogens. These divergent observations prompted a re-evaluation of ATG16L1 in innate antimicrobial immunity. In this study, we found that loss of Atg16l1 in myeloid cells enhanced the killing of virulent Shigella flexneri (S.flexneri), a clinically relevant enteric bacterium that resides within the cytosol by escaping from membrane-bound compartments. Quantitative multiplexed proteomics of murine bone marrow-derived macrophages revealed that ATG16L1 deficiency significantly upregulated proteins involved in the glutathione-mediated antioxidant response to compensate for elevated oxidative stress, which simultaneously promoted S.flexneri killing. Consistent with this, myeloid-specific deletion of Atg16l1 in mice accelerated bacterial clearance in vitro and in vivo. Pharmacological induction of oxidative stress through suppression of cysteine import enhanced microbial clearance by macrophages. Conversely, antioxidant treatment of macrophages permitted S.flexneri proliferation. These findings demonstrate that control of oxidative stress by ATG16L1 and autophagy regulates antimicrobial immunity against intracellular pathogens.

Sirt1 deacetylates and stabilizes p62 to promote hepato-carcinogenesis

p62/SQSTM1 is frequently up-regulated in many cancers including hepatocellular carcinoma. Highly expressed p62 promotes hepato-carcinogenesis by activating many signaling pathways including Nrf2, mTORC1, and NFκB signaling. However, the underlying mechanism for p62 up-regulation in hepatocellular carcinoma remains largely unclear. Herein, we confirmed that p62 was up-regulated in hepatocellular carcinoma and its higher expression was associated with shorter overall survival in patients. The knockdown of p62 in hepatocellular carcinoma cells decreased cell growth in vitro and in vivo. Intriguingly, p62 protein stability could be reduced by its acetylation at lysine 295, which was regulated by deacetylase Sirt1 and acetyltransferase GCN5. Acetylated p62 increased its association with the E3 ligase Keap1, which facilitated its poly-ubiquitination-dependent proteasomal degradation. Moreover, Sirt1 was up-regulated to deacetylate and stabilize p62 in hepatocellular carcinoma. Additionally, Hepatocyte Sirt1 conditional knockout mice developed much fewer liver tumors after Diethynitrosamine treatment, which could be reversed by the re-introduction of exogenous p62. Taken together, Sirt1 deacetylates p62 at lysine 295 to disturb Keap1-mediated p62 poly-ubiquitination, thus up-regulating p62 expression to promote hepato-carcinogenesis. Therefore, targeting Sirt1 or p62 is a reasonable strategy for the treatment of hepatocellular carcinoma.

Dehydrodiisoeugenol inhibits colorectal cancer growth by endoplasmic reticulum stress-induced autophagic pathways

Background

Dehydrodiisoeugenol (DEH), a novel lignan component extracted from nutmeg, which is the seed of Myristica fragrans Houtt, displays noticeable anti-inflammatory and anti-allergic effects in digestive system diseases. However, the mechanism of its anticancer activity in gastrointestinal cancer remains to be investigated.

Methods

In this study, the anticancer effect of DEH on human colorectal cancer and its underlying mechanism were evaluated. Assays including MTT, EdU, Plate clone formation, Soft agar, Flow cytometry, Electron microscopy, Immunofluorescence and Western blotting were used in vitro. The CDX and PDX tumor xenograft models were used in vivo.

Results

Our findings indicated that treatment with DEH arrested the cell cycle of colorectal cancer cells at the G1/S phase, leading to significant inhibition in cell growth. Moreover, DEH induced strong cellular autophagy, which could be inhibited through autophagic inhibitors, with a rction in the DEH-induced inhibition of cell growth in colorectal cancer cells. Further analysis indicated that DEH also induced endoplasmic reticulum (ER) stress and subsequently stimulated autophagy through the activation of PERK/eIF2α and IRE1α/XBP-1 s/CHOP pathways. Knockdown of PERK or IRE1α significantly decreased DEH-induced autophagy and retrieved cell viability in cells treated with DEH. Furthermore, DEH also exhibited significant anticancer activities in the CDX- and PDX-models.

Conclusions

Collectively, our studies strongly suggest that DEH might be a potential anticancer agent against colorectal cancer by activating ER stress-induced inhibition of autophagy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01915-9.

Prognostic Impact of PCK1 Protein Kinase Activity-Dependent Nuclear SREBP1 Activation in Non-Small-Cell Lung Carcinoma

Metabolic enzymes can perform non-metabolic functions and play critical roles in the regulation of a variety of important cellular activities. Phosphoenolpyruvate carboxykinase 1 (PCK1), a gluconeogenesis enzyme, was recently identified as an AKT-regulated protein kinase that phosphorylates INSIG1/2 to promote nuclear SREBP1-dependent lipogenesis. However, the relationship of this regulation with the progression of non-small-cell lung carcinoma (NSCLC) is unclear. Here, we demonstrate that epidermal growth factor receptor (EGFR) activation induces AKT-dependent PCK1 pS90, PCK1-mediated INSIG1 pS207/INSIG2 pS151, and nuclear SREBP1 accumulation in NSCLC cells. In addition, the expression levels of AKT pS473, PCK1 pS90, INSIG1 pS207/INSIG2 pS151, and nuclear SREBP1 are higher in 451 analyzed human NSCLC specimens than in their adjacent normal tissues and positively correlated with each other in the tumor specimens. Furthermore, the expression levels of PCK1 pS90, INSIG1 pS207/INSIG2 pS151, and nuclear SREBP1 are associated with TNM stage and progression in NSCLC. Importantly, levels of PCK1 pS90 or INSIG1 pS207/INSIG2 pS151 are positively correlated with poor prognosis in NSCLC patients, and the combined expression value of the PCK1 and INSIG1/2 phosphorylation has a better prognostic value than that of each individual protein phosphorylation value and is an independent prognostic marker for NSCLC. These findings reveal the role of PCK1-mediated nuclear SREBP1 activation in NSCLC progression and highlight the potential to target the protein kinase activity of PCK1 for the diagnosis and treatment of human NSCLC.

Autophagy, an accomplice or antagonist of drug resistance in HCC?

Hepatocellular carcinoma (HCC) is a highly lethal malignancy characterized by poor prognosis and a low 5-year survival rate. Drug treatment is proving to be effective in anti-HCC. However, only a small number of HCC patients exhibit sensitive responses, and drug resistance occurs frequently in advanced patients. Autophagy, an evolutionary process responsible for the degradation of cellular substances, is closely associated with the acquisition and maintenance of drug resistance for HCC. This review focuses on autophagic proteins and explores the intricate relationship between autophagy and cancer stem cells, tumor-derived exosomes, and noncoding RNA. Clinical trials involved in autophagy inhibition combined with anticancer drugs are also concerned.

The Evolving Landscape of Noncanonical Functions of Metabolic Enzymes in Cancer and Other Pathologies

Key pathological, including oncogenic, signaling pathways regulate the canonical functions of metabolic enzymes that serve the cellular metabolic needs. Importantly, these signaling pathways also confer a large number of metabolic enzymes to have noncanonical or nonmetabolic functions that are referred to as "moonlighting" functions. In this review, we highlight how aberrantly regulated metabolic enzymes with such activities play critical roles in the governing of a wide spectrum of instrumental cellular activities, including gene expression, cell-cycle progression, DNA repair, cell proliferation, survival, apoptosis, and tumor microenvironment remodeling, thereby promoting the pathologic progression of disease, including cancer.

MOAP-1-mediated dissociation of p62/SQSTM1 bodies releases Keap1 and suppresses Nrf2 signaling

Nrf2 signaling is vital for protecting cells against oxidative stress. However, its hyperactivation is frequently found in liver cancer through excessive build‐up of p62/SQSTM1 bodies that sequester Keap1, an adaptor of the E3‐ubiquitin ligase complex for Nrf2. Here, we report that the Bax‐binding protein MOAP‐1 regulates p62‐Keap1‐Nrf2 signaling through disruption of p62 bodies. Upon induction of cellular stresses that stimulate formation of p62 bodies, MOAP‐1 is recruited to p62 bodies and reduces their levels independent of the autophagy pathway. MOAP‐1 interacts with the PB1‐ZZ domains of p62 and interferes with its self‐oligomerization and liquid–liquid phase separation, thereby disassembling the p62 bodies. Loss of MOAP‐1 can lead to marked upregulation of p62 bodies, enhanced sequestration of Keap1 by p62 and hyperactivation of Nrf2 antioxidant target genes. MOAP‐1‐deficient mice exhibit an elevated tumor burden with excessive levels of p62 bodies and Nrf2 signaling in a diethylnitrosamine (DEN)‐induced hepatocarcinogenesis model. Together, our data define MOAP‐1 as a negative regulator of Nrf2 signaling via dissociation of p62 bodies.

Proteins moonlighting in tumor metabolism and epigenetics

Cancer development is a complicated process controlled by the interplay of multiple signaling pathways and restrained by oxygen and nutrient accessibility in the tumor microenvironment. High plasticity in using diverse nutrients to adapt to metabolic stress is one of the hallmarks of cancer cells. To respond to nutrient stress and to meet the requirements for rapid cell proliferation, cancer cells reprogram metabolic pathways to take up more glucose and coordinate the production of energy and intermediates for biosynthesis. Such actions involve gene expression and activity regulation by the moonlighting function of oncoproteins and metabolic enzymes. The signal - moonlighting protein - metabolism axis facilitates the adaptation of tumor cells under varying environment conditions and can be therapeutically targeted for cancer treatment.

Association of phosphoenolpyruvate carboxykinase 1 protein kinase activity-dependent sterol regulatory element-binding protein 1 activation with prognosis of oesophageal carcinoma

BACKGROUND

Metabolic enzymes have non-canonical functions and play vital roles in the regulation of various cellular activities. Phosphoenolpyruvate carboxykinase 1 (PCK1), a gluconeogenic enzyme, was recently identified as an AKT-dependent protein kinase and promoted sterol regulatory element-binding protein 1 (SREBP1)-dependent lipogenesis. However, association of this protein kinase activity of PCK1 with progression of oesophageal squamous cell carcinoma (ESCC) is unclear.

METHODS

We examined 200 ESCC patient samples and prognosis using immunohistochemistry, multivariate Cox regression and Kaplan-Meier Plot analyses.

RESULTS

We show that the expression levels of AKT pS473, AKT-regulated PCK1 pS90, PCK1-mediated INSIG1 pS207/INSIG2 pS151 and nuclear SREBP1 were higher in analysed 200 human ESCC specimens than in their adjacent non-tumour tissues; the expression levels of these proteins were significantly and positively correlated with each other in tumour specimens. In addition, the expression levels of PCK1 pS90, INSIG1 pS207/INSIG2 pS151 and SREBP1 were associated with the tumour, node and metastasis stage and progression in ESCC. Importantly, levels of PCK1 pS90 or INSIG1 pS207/INSIG2 pS151 or nuclear SREBP1 were positively correlated with poor prognosis in patients with ESCC, and the combined expression values of PCK1 pS90, INSIG1 pS207/INSIG2 pS151 and nuclear SREBP1 had a better prognostic value than that of each individual protein expression value and was an independent prognostic marker for ESCC.

CONCLUSION

These findings reveal the role of PCK1 protein kinase activity-dependent SREBP1 activation in ESCC progression. The regulation of SREBP1 by AKT activation-dependent PCK1 protein kinase activity may provide the potential for the diagnosis and treatment of human ESCC.