Regulation of HK2 expression through alterations in CpG methylation of the HK2 promoter during progression of hepatocellular carcinoma

Related mechanisms, current treatments, and new perspectives in meningioma

Meningiomas are non-glial tumors that are the most common primary brain tumors in adults. Although meningioma can possibly be cured with surgical excision, variations in atypical/anaplastic meningioma have a high recurrence rate and a poor prognosis. As a result, it is critical to develop novel therapeutic options for high-grade meningiomas. This review highlights the current histology of meningiomas, prevalent genetic and molecular changes, and the most extensively researched signaling pathways and therapies in meningiomas. It also reviews current clinical studies and novel meningioma treatments, including immunotherapy, microRNAs, cancer stem cell methods, and targeted interventions within the glycolysis pathway. Through the examination of the complex landscape of meningioma biology and the highlighting of promising therapeutic pathways, this review opens the way for future research efforts aimed at improving patient outcomes in this prevalent intracranial tumor entity.

Aiding Cancer's "Sweet Tooth": Role of Hexokinases in Metabolic Reprogramming

Hexokinases (HKs) convert hexose sugars to hexose-6-phosphate, thus trapping them inside cells to meet the synthetic and energetic demands. HKs participate in various standard and altered physiological processes, including cancer, primarily through the reprogramming of cellular metabolism. Four canonical HKs have been identified with different expression patterns across tissues. HKs 1-3 play a role in glucose utilization, whereas HK 4 (glucokinase, GCK) also acts as a glucose sensor. Recently, a novel fifth HK, hexokinase domain containing 1 (HKDC1), has been identified, which plays a role in whole-body glucose utilization and insulin sensitivity. Beyond the metabolic functions, HKDC1 is differentially expressed in many forms of human cancer. This review focuses on the role of HKs, particularly HKDC1, in metabolic reprogramming and cancer progression.

The Role of Reprogrammed Glucose Metabolism in Cancer

Cancer cells reprogram their metabolism to meet biosynthetic needs and to adapt to various microenvironments. Accelerated glycolysis offers proliferative benefits for malignant cells by generating glycolytic products that move into branched pathways to synthesize proteins, fatty acids, nucleotides, and lipids. Notably, reprogrammed glucose metabolism and its associated events support the hallmark features of cancer such as sustained cell proliferation, hijacked apoptosis, invasion, metastasis, and angiogenesis. Overproduced enzymes involved in the committed steps of glycolysis (hexokinase, phosphofructokinase-1, and pyruvate kinase) are promising pharmacological targets for cancer therapeutics. In this review, we summarize the role of reprogrammed glucose metabolism in cancer cells and how it can be manipulated for anti-cancer strategies.

18F-FDG PET as an imaging biomarker for the response to FGFR-targeted therapy of cancer cells via FGFR-initiated mTOR/HK2 axis

Rationale: The overall clinical response to FGFR inhibitor (FGFRi) is far from satisfactory in cancer patients stratified by FGFR aberration, the current biomarker in clinical practice. A novel biomarker to evaluate the therapeutic response to FGFRi in a non-invasive and dynamic manner is thus greatly desired. Methods: Six FGFR-aberrant cancer cell lines were used, including four FGFRi-sensitive ones (NCI-H1581, NCI-H716, RT112 and Hep3B) and two FGFRi-resistant ones (primary for NCI-H2444 and acquired for NCI-H1581/AR). Cell viability and tumor xenograft growth analyses were performed to evaluate FGFRi sensitivities, accompanied by corresponding ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake assay. mTOR/PLCγ/MEK-ERK signaling blockade by specific inhibitors or siRNAs was applied to determine the regulation mechanism. Results: FGFR inhibition decreased the in vitro accumulation of ¹⁸F-FDG only in four FGFRi-sensitive cell lines, but in neither of FGFRi-resistant ones. We then demonstrated that FGFRi-induced transcriptional downregulation of hexokinase 2 (HK2), a key factor of glucose metabolism and FDG trapping, via mTOR pathway leading to this decrease. Moreover, ¹⁸F-FDG PET imaging successfully differentiated the FGFRi-sensitive tumor xenografts from primary or acquired resistant ones by the tumor ¹⁸F-FDG accumulation change upon FGFRi treatment. Of note, both ¹⁸F-FDG tumor accumulation and HK2 expression could respond the administration/withdrawal of FGFRi in NCI-H1581 xenografts correspondingly. Conclusion: The novel association between the molecular mechanism (FGFR/mTOR/HK2 axis) and radiological phenotype (¹⁸F-FDG PET uptake) of FGFR-targeted therapy was demonstrated in multiple preclinical models. The adoption of ¹⁸F-FDG PET biomarker-based imaging strategy to assess response/resistance to FGFR inhibition may benefit treatment selection for cancer patients.

Stress Responses as Master Keys to Epigenomic Changes in Transcriptome and Metabolome for Cancer Etiology and Therapeutics

From initiation through progression, cancer cells are subjected to a magnitude of endogenous and exogenous stresses, which aid in their neoplastic transformation. Exposure to these classes of stress induces imbalance in cellular homeostasis and, in response, cancer cells employ informative adaptive mechanisms to rebalance biochemical processes that facilitate survival and maintain their existence. Different kinds of stress stimuli trigger epigenetic alterations in cancer cells, which leads to changes in their transcriptome and metabolome, ultimately resulting in suppression of growth inhibition or induction of apoptosis. Whether cancer cells show a protective response to stress or succumb to cell death depends on the type of stress and duration of exposure. A thorough understanding of epigenetic and molecular architecture of cancer cell stress response pathways can unveil a plethora of information required to develop novel anticancer therapeutics. The present view highlights current knowledge about alterations in epigenome and transcriptome of cancer cells as a consequence of exposure to different physicochemical stressful stimuli such as reactive oxygen species (ROS), hypoxia, radiation, hyperthermia, genotoxic agents, and nutrient deprivation. Currently, an anticancer treatment scenario involving the imposition of stress to target cancer cells is gaining traction to augment or even replace conventional therapeutic regimens. Therefore, a comprehensive understanding of stress response pathways is crucial for devising and implementing novel therapeutic strategies.

Modulation of DNA/RNA Methylation Signaling Mediating Metabolic Homeostasis in Cancer

Nucleic acid methylation is a fundamental epigenetic mechanism that impinges upon several cellular attributes, including metabolism and energy production. The dysregulation of deoxyribonucleic acid (DNA)/ribonucleic acid (RNA) methylation can lead to metabolic rewiring in the cell, which in turn facilitates tumor development. Here, we review the current knowledge on the interplay between DNA/RNA methylation and metabolic programs in cancer cells. We also discuss the mechanistic role of these pathways in tumor development and progression.

Dysregulation of the miR-1275/HK2 Axis Contributes to the Progression of Hypoxia/Reoxygenation-Induced Myocardial Injury

OBJECTIVE

This research was designed to investigate the function of miR-1275 in hypoxia/reoxygenation (H/R)-induced myocardial injury and its in-depth mechanism.

METHODS

Firstly, the differential expression of miR-1275 in patients with heart failure and healthy control were analyzed based on Gene Expression Omnibus (GEO) database. Then H/R model was constructed in vitro with AC16 cells. The qRT-PCR assay was performed to analyze the expression of miR-1275 in H/R-treated cells. Afterwards, CCK-8 assay and flow cytometry assay were carried out to detect the cells viability and apoptosis. Bioinformatics prediction, western blotting and dual-luciferase reporter assays were set to check the target gene of miR-1275. Finally, we used an Elisa to test the effect of miR-1275/HK2 axis on inflammatory factors.

RESULTS

We found that miR-1275 was highly expressed in patients with heart failure and H/R treated AC16 cells than that in control group, and inhibition of miR-1275 can alleviate induced-decrease of cell viability. Subsequently, we revealed that HK2 was a downstream target gene of miR-1275, which was lowly expressed in patients with heart failure. Furthermore, our data also suggested that inhibition of miR-1275 can significantly alleviate H/R-induced myocardial injury, which can also markedly decrease the concentration of pro-inflammatory factors TNF-α, IL-1 β and increase the concentration of anti-inflammatory factors IL-10 in H/R-treated AC16 cells, while knockdown of HK2 canceled the effect caused by miR-1275 deletion.

CONCLUSIONS

In summing, our results illustrated that miR-1275/HK2 axis act as a potential regulator to against H/R-induced AC16 cells injury through anti-inflammatory effect.

Genome-Wide Analysis of Cell-Free DNA Methylation Profiling for the Early Diagnosis of Pancreatic Cancer

As one of the most malicious cancers, pancreatic cancer is difficult to treat due to the lack of effective early diagnosis. Therefore, it is urgent to find reliable diagnostic and predictive markers for the early detection of pancreatic cancer. In recent years, the detection of circulating cell-free DNA (cfDNA) methylation in plasma has attracted global attention for non-invasive and early cancer diagnosis. Here, we carried out a genome-wide cfDNA methylation profiling study of pancreatic ductal adenocarcinoma (PDAC) patients by methylated DNA immunoprecipitation coupled with high-throughput sequencing (MeDIP-seq). Compared with healthy individuals, 775 differentially methylated regions (DMRs) located in promoter regions were identified in PDAC patients with 761 hypermethylated and 14 hypomethylated regions; meanwhile, 761 DMRs in CpG islands (CGIs) were identified in PDAC patients with 734 hypermethylated and 27 hypomethylated regions (p-value < 0.0001). Then, 143 hypermethylated DMRs were further selected which were located in promoter regions and completely overlapped with CGIs. After performing the least absolute shrinkage and selection operator (LASSO) method, a total of eight markers were found to fairly distinguish PDAC patients from healthy individuals, including TRIM73, FAM150A, EPB41L3, SIX3, MIR663, MAPT, LOC100128977, and LOC100130148. In conclusion, this work identified a set of eight differentially methylated markers that may be potentially applied in non-invasive diagnosis of pancreatic cancer.

Transplantation of a Novel Recombinant Adeno-Associated Virus (pAAV-HE1B19K-TE1A) Demonstrates Higher Anti-Tumor Effects in Tumor Cells

BACKGROUND Oncolytic viruses (OVs) can specifically infect and kill tumor cells. Adeno-associated virus (AAV) is a widely-studied OV. This study aimed to construct a tumor-targeted recombinant AAV using genetic engineering technology. MATERIAL AND METHODS The transgene plasmid pAAV-HE1B19K-TE1A was constructed with 4 genes (hTERT, E1A, HKII, and E1B19K) and co-transfected with pAAV-RC and pHelper to tumor cells (HepG2, A549, BGC-803) and normal cells (HUVEC). rAAV was verified with fluorescence microscopy. Quantitative PCR (qPCR) assay was used to test the titer of rAAV in each cell line. Apoptosis was analyzed using qPCR and Western blot assay. MTT was used to detect the effect of rAAV on cell viability. RESULTS The pAAV-HE1B19K-TE1A transgene plasmid was successfully structured. pAAV-HE1B19K-TE1A was highly expressed in all tumor cells. The titers of pAAV-HE1B19K-TE1A in HepG2, A549, and BGC-803 were 7.4×10⁷, 1.4×10⁸, and 1.1×10⁸ gc/μl, respectively. pAAV-HE1B19K-TE1A significantly decreased cell viability of tumor cells compared to that in HUVEC (p<0.05). pAAV-HE1B19K-TE1A remarkably triggered cleaved caspase 3 (C-caspase 3) activity in tumor cells compared to that in untransfected tumor cells (p<0.05). pAAV-HE1B19K-TE1A significantly induced release of cytochrome C (Cyto C) in tumor cells compared to that in untransfected tumor cells (p<0.05). pAAV-HE1B19K-TE1A demonstrated no toxicity to vital tissues of animals. CONCLUSIONS Tumor-targeted rAAV was successfully produced using the Helper-free system with recombinant plasmid, demonstrating high efficacy in decreasing viability of tumor cells without adverse effects on normal cells.

The long non-coding RNA SNHG1 promotes bladder cancer progression by interacting with miR-143-3p and EZH2

The long non-coding RNA (lncRNA) SNHG1 has been shown to be implicated in the progression of multiple human carcinomas. Nevertheless, the biological functions and potential mechanism of SNHG1 in bladder cancer (BC) are uncharacterized. In the present study, SNHG1 was found to be substantially up-regulated in BC tissues and cells and was intimately correlated with the TNM stage, lymphatic invasion, metastasis and recurrence-free survival in BC patients. Down-regulation of SNHG1 dramatically attenuated the proliferation, migration and invasion of BC cells, whereas the ectopic overexpression of SNHG1 had the opposite effects in vitro. The in vivo experimental results also indicated that SNHG1 down-regulation hampered the tumour growth and metastasis of BC cells. Mechanistic investigations revealed that SNHG1 enhances HK2 expression by serving as an endogenous sponge to regulate miR-143-3p in the cytoplasm of BC cells. In the nucleus, SNHG1 could interact with EZH2 and regulate the histone methylation of the CDH1 promoter, altering the biological behaviours of BC cells. Overall, these findings elucidate an oncologic role of SNHG1 in BC and provide a new therapeutic strategy against BC.

Cyclin D1 targets hexokinase 2 to control aerobic glycolysis in myeloma cells

Cancer cells are characterized by the Warburg effect, a shift from mitochondrial respiration to oxidative glycolysis. We report here the crucial role of cyclin D1 in promoting this effect in a cyclin-dependent kinase (CDK)4/6-independent manner in multiple myeloma (MM) cells. We show that the cyclin D1 oncoprotein targets hexokinase 2 (HK2), a major glycolysis regulator, through two original molecular mechanisms in the cytoplasmic and nuclear compartments. In the cytoplasm, cyclin D1 binds HK2 at the outer mitochondrial membrane, and in the nucleus, it binds hypoxia-inducible factor-1α (HIF1α), which regulates HK2 gene transcription. We also show that high levels of HK2 expression are correlated with shorter event-free survival (EFS) and overall survival (OS) in MM patients. HK2 may therefore be considered as a possible target for antimyeloma therapy.

Qiliqiangxin Improves Cardiac Function through Regulating Energy Metabolism via HIF-1α-Dependent and Independent Mechanisms in Heart Failure Rats after Acute Myocardial Infarction

The present study is aimed at investigating whether Qiliqiangxin (QL) could regulate myocardial energy metabolism in heart failure rats after acute myocardial infarction (AMI) and further exploring the underlying mechanisms. AMI was established by ligating the left anterior descending coronary artery in adult male SD rats. AMI rats with ejection fraction (EF) < 50% at two weeks after the operation were chosen as heart failure rats for the main study. Rats were randomized into the sham, MI, MI+QL, and MI+QL+2-MeOE2 groups. The results showed that compared with the MI group, QL significantly improved cardiac function, reduced serum NT-proBNP level, and alleviated myocardial fibrosis. QL also increased myocardial capillary density by upregulated protein expressions of vascular endothelial growth factor (VEGF) and CD31 by regulating the HIF-1α/VEGF pathway. Moreover, QL promoted ATP production, glucose uptake, and glycolysis by upregulating HIF-1α and a series of glycolysis-relevant enzymes in a HIF-1α-dependent manner. QL also improved myocardial glucose oxidation enzyme expression and free fatty acid uptake by a HIF-1α-independent pathway. Our results indicate that QL treatment improves cardiac function through regulating glucose uptake, FFA uptake, and key enzymes of energy metabolism via HIF-1α-dependent and independent mechanisms.

miR-125a-5p inhibits glycolysis by targeting hexokinase-II to improve pulmonary arterial hypertension

Purpose: The aim of this study was to investigate the effect of microRNAs on the proliferation of pulmonary arterial smooth muscle cells (PASMCs) as a result of targeting hexokinase-II (HK-II) and its mechanism of action.

Results: Differences in metabolic patterns were found between the normal group and monocrotaline-induced pulmonary arterial hypertension (MCT-PH) group. miR-125a-5p decreased glycolysis levels of monocrotaline (MCT)-induced PASMCs by targeting HK-II and inhibiting its proliferation. In vivo experiments found that miR-125a-5p agomir upregulated HK-II expression in the MCT-PH. Right ventricular hypertrophy was reversed and cardiac function improved as a result of decreased mean pulmonary artery pressure (mPAP).

Conclusion: In vitro and in vivo experiments both confirmed that miR-125a-5p could inhibit cell glycolysis and PASMC proliferation to improve PAH by targeting HK-II.

Methods: HK-II overexpression was constructed, and differentially expressed microRNAs were screened for using microarrays. Serum metabolites were detected using Nuclear Magnetic Resonance (NMR). Through screening for characteristic metabolites in rat body fluids and by analyzing biological functions, disordered metabolic pathways were identified. Activity of the miR-125a-5p target HK-II was measured using a luciferase reporter assay. Expression of downstream molecules was measured by RT–qPCR and/or western blot. Glucose consumption and lactic acid production were analyzed and used as a reflection of glycolysis.

MicroRNA-513a-3p regulates colorectal cancer cell metabolism via targeting hexokinase 2

Disruption of cell metabolism is a hallmark of cancer cells. Accumulating evidence suggests that microRNAs (miRNAs/miRs) are involved in almost all physiological and pathological processes. The aberrant expression of miRNAs induces metabolic reprogramming in cancer cells and thus, promotes proliferation. In the current study, miR-513a-3p was identified as a significantly downregulated miRNA in colorectal cancer cells and tumors. Overexpression of miR-513a-3p in colorectal cancer cells inhibited proliferation and glycolysis. A well-documented metabolic regulator, hexokinase 2 (HK2), was predicted and validated HK2to be a target gene of miR-513a-3p in colorectal cancer cells. In addition, overexpression of HK2 reversed the miR-513a-3p mimic-induced inhibition of proliferation. The association between HK2 and miR-513a-3p was further observed in tumors collected from patients with colorectal cancer. The findings suggest that miR-513a-5p may inhibit glycolysis in colorectal cancer cells via repressing HK2 expression, indicating that miR-513a-5p may be a tumor suppressor in colorectal cancer.

Research Progress in Liver-Regenerating Microenvironment and DNA Methylation in Hepatocellular Carcinoma: The Role of Traditional Chinese Medicine

The development, progression, recurrence, and metastasis of hepatocellular carcinoma (HCC) are closely associated with an abnormal liver-regenerating microenvironment (LRM). Therefore, preventing and reversing an abnormal LRM is a potential therapeutic strategy against HCC. Studies are increasingly focusing on the impact of regeneration, fibrosis, angiogenesis, inflammation, immunomodulation, and hepatic stem cells on HCC development and progression. As a key epigenetic mechanism, DNA methylation is extensively involved in regulating physiological and pathological pathways. In this review, we summarize recent findings on the role of DNA methylation in the fibrotic, angiogenic, inflammatory/immune, and stem cell microenvironments of HCC, and discuss new advances in Traditional Chinese Medicine (TCM) on influencing the abnormal LRM, so as to gain new insights into alleviating the abnormal LRM via regulating DNA methylation by TCM.

Regulatory Role of Hexokinase 2 in Modulating Head and Neck Tumorigenesis

To support great demand of cell growth, cancer cells preferentially obtain energy and biomacromolecules by glycolysis over mitochondrial oxidative phosphorylation (OxPhos). Among all glycolytic enzymes, hexokinase (HK), a rate-limiting enzyme at the first step of glycolysis to catalyze cellular glucose into glucose-6-phosphate, is herein emphasized. Four HK isoforms, HK1-HK4, were discovered in nature. It was shown that HK2 expression is enriched in many tumor cells and correlated with poorer survival rates in most neoplastic cells. HK2-mediated regulations for cell malignancy and mechanistic cues in regulating head and neck tumorigenesis, however, are not fully elucidated. Cellular malignancy index, such as cell growth, cellular motility, and treatment sensitivity, and molecular alterations were determined in HK2-deficient head and neck squamous cell carcinoma (HNSCC) cells. By using various cancer databases, HK2, but not HK1, positively correlates with HNSCC progression in a stage-dependent manner. A high HK2 expression was detected in head and neck cancerous tissues compared with their normal counterparts, both in mouse and human subjects. Loss of HK2 in HNSCC cells resulted in reduced cell (in vitro) and tumor (in vivo) growth, as well as decreased epithelial-mesenchymal transition–mediated cell movement; in contrast, HK2-deficient HNSCC cells exhibited greater sensitivity to chemotherapeutic drugs cisplatin and 5-fluorouracil but are more resistant to photodynamic therapy, indicating that HK2 expression could selectively define treatment sensitivity in HNSCC cells. At the molecular level, it was found that HK2 alteration drove metabolic reprogramming toward OxPhos and modulated oncogenic Akt and mutant TP53-mediated signals in HNSCC cells. In summary, the present study showed that HK2 suppression could lessen HNSCC oncogenicity and modulate therapeutic sensitivity, thereby being an ideal therapeutic target for HNSCCs.

Metabolic Dysregulations and Epigenetics: A Bidirectional Interplay that Drives Tumor Progression

Cancer has been considered, for a long time, a genetic disease where mutations in keyregulatory genes drive tumor initiation, growth, metastasis, and drug resistance. Instead, theadvent of high-throughput technologies has revolutionized cancer research, allowing to investigatemolecular alterations at multiple levels, including genome, epigenome, transcriptome, proteome,and metabolome and showing the multifaceted aspects of this disease. The multi-omics approachesrevealed an intricate molecular landscape where different cellular functions are interconnected andcooperatively contribute to shaping the malignant phenotype. Recent evidence has brought to lighthow metabolism and epigenetics are highly intertwined, and their aberrant crosstalk can contributeto tumorigenesis. The oncogene-driven metabolic plasticity of tumor cells supports the energeticand anabolic demands of proliferative tumor programs and secondary can alter the epigeneticlandscape via modulating the production and/or the activity of epigenetic metabolites. Conversely,epigenetic mechanisms can regulate the expression of metabolic genes, thereby altering themetabolome, eliciting adaptive responses to rapidly changing environmental conditions, andsustaining malignant cell survival and progression in hostile niches. Thus, cancer cells takeadvantage of the epigenetics-metabolism crosstalk to acquire aggressive traits, promote cellproliferation, metastasis, and pluripotency, and shape tumor microenvironment. Understandingthis bidirectional relationship is crucial to identify potential novel molecular targets for theimplementation of robust anti-cancer therapeutic strategies.

Hexokinase-2 Glycolytic Overload in Diabetes and Ischemia-Reperfusion Injury

Hexokinase-2 (HK2) was recently found to produce increased metabolic flux through glycolysis in hyperglycemia without concurrent transcriptional or other functional regulation. Rather, stabilization to proteolysis by increased glucose substrate binding produced unscheduled increased glucose metabolism in response to high cytosolic glucose concentration. This produces abnormal increases in glycolytic intermediates or glycolytic overload, driving cell dysfunction and vulnerability to the damaging effects of hyperglycemia in diabetes, explaining tissue-specific pathogenesis. Glycolytic overload is also activated in ischemia-reperfusion injury and cell senescence. A further key feature is HK2 displacement from mitochondria by increased glucose-6-phosphate concentration, inducing mitochondrial dysfunction and oxidative stress. This pathogenic mechanism suggested new targets for therapeutics development that gave promising outcomes in initial clinical evaluation.

The CIMP-high phenotype is associated with energy metabolism alterations in colon adenocarcinoma

BACKGROUND

CpG island methylator phenotype (CIMP) is found in 15-20% of malignant colorectal tumors and is characterized by strong CpG hypermethylation over the genome. The molecular mechanisms of this phenomenon are not still fully understood. The development of CIMP is followed by global gene expression alterations and metabolic changes. In particular, CIMP-low colon adenocarcinoma (COAD), predominantly corresponded to consensus molecular subtype 3 (CMS3, "Metabolic") subgroup according to COAD molecular classification, is associated with elevated expression of genes participating in metabolic pathways.

METHODS

We performed bioinformatics analysis of RNA-Seq data from The Cancer Genome Atlas (TCGA) project for CIMP-high and non-CIMP COAD samples with DESeq2, clusterProfiler, and topGO R packages. Obtained results were validated on a set of fourteen COAD samples with matched morphologically normal tissues using quantitative PCR (qPCR).

RESULTS

Upregulation of multiple genes involved in glycolysis and related processes (ENO2, PFKP, HK3, PKM, ENO1, HK2, PGAM1, GAPDH, ALDOA, GPI, TPI1, and HK1) was revealed in CIMP-high tumors compared to non-CIMP ones. Most remarkably, the expression of the PKLR gene, encoding for pyruvate kinase participating in gluconeogenesis, was decreased approximately 20-fold. Up to 8-fold decrease in the expression of OGDHL gene involved in tricarboxylic acid (TCA) cycle was observed in CIMP-high tumors. Using qPCR, we confirmed the increase (4-fold) in the ENO2 expression and decrease (2-fold) in the OGDHL mRNA level on a set of COAD samples.

CONCLUSIONS

We demonstrated the association between CIMP-high status and the energy metabolism changes at the transcriptomic level in colorectal adenocarcinoma against the background of immune pathway activation. Differential methylation of at least nine CpG sites in OGDHL promoter region as well as decreased OGDHL mRNA level can potentially serve as an additional biomarker of the CIMP-high status in COAD.

Crucial role of the pentose phosphate pathway in malignant tumors

Interest in cancer metabolism has increased in recent years. The pentose phosphate pathway (PPP) is a major glucose catabolism pathway that directs glucose flux to its oxidative branch and leads to the production of a reduced form of nicotinamide adenine dinucleotide phosphate and nucleic acid. The PPP serves a vital role in regulating cancer cell growth and involves many enzymes. The aim of the present review was to describe the recent discoveries associated with the deregulatory mechanisms of the PPP and glycolysis in malignant tumors, particularly in hepatocellular carcinoma, breast and lung cancer.

Tristetraprolin-mediated hexokinase 2 expression regulation contributes to glycolysis in cancer cells

Hexokinase 2 (HK2) catalyzes the first step of glycolysis and is up-regulated in cancer cells. The mechanism has not been fully elucidated. Tristetraprolin (TTP) is an AU-rich element (ARE)-binding protein that inhibits the expression of ARE-containing genes by enhancing mRNA degradation. TTP expression is down-regulated in cancer cells. We demonstrated that TTP is critical for down-regulation of HK2 expression in cancer cells. HK2 mRNA contains an ARE within its 3'-UTR. TTP binds to HK2 3'-UTR and enhances degradation of HK2 mRNA. TTP overexpression decreased HK2 expression and suppressed the glycolytic capacity of cancer cells, measured as glucose uptake and production of glucose-6-phosphate, pyruvate, and lactate. TTP overexpression reduced both the extracellular acidification rate (ECAR) and the oxygen consumption rate (OCR) of cancer cells. Ectopic expression of HK2 in cancer cells attenuated the reduction in glycolytic capacity, ECAR, and OCR from TTP. Taken together, these findings suggest that TTP acts as a negative regulator of HK2 expression and glucose metabolism in cancer cells.

The landscape of DNA methylation in hepatocellular carcinoma

Better understanding of the relationship between changes in the overall methylation status of hepatocellular carcinoma (HCC) and disease progression will help us find good strategies for the early detection and treatment of HCC patients. The purpose of the study was to study the relations between the methylation status changes in HCC patients and progression of the disease to enable early detection and treatment of HCC patients. First, the DNA methylation data of 50 HCC samples and the surrounding normal samples were extracted and the change pattern of methylation status in the DNA promoter region of HCC samples against that of normal samples was studied. Then, some DNA methylation genes that could accurately identify cancer and cancer-adjacent tissues were identified using the k-top scoring pair method. Also, a prognostic signature that could predict the survival of HCC patients was constructed based on the overall survival time and death information of the early HCC patients. Finally, the obtained prognostic signature was verified. In conclusion, this study described the changes in the methylation spectrum during the development of HCC and identified genes associated with HCC progression and prognosis, which may offer new opportunities for the diagnosis and treatment of HCC.

Sequential decitabine and carboplatin treatment increases the DNA repair protein XPC, increases apoptosis and decreases proliferation in melanoma

BACKGROUND

Melanoma has two key features, an over-representation of UV-induced mutations and resistance to DNA damaging chemotherapy agents. Both of these features may result from dysfunction of the nucleotide excision repair pathway, in particular the DNA damage detection branch, global genome repair (GGR). The key GGR component XPC does not respond to DNA damage in melanoma, the cause of this lack of response has not been investigated. In this study, we investigated the role of methylation in reduced XPC in melanoma.

METHODS

To reduce methylation and induce DNA-damage, melanoma cell lines were treated with decitabine and carboplatin, individually and sequentially. Global DNA methylation levels, XPC mRNA and protein expression and methylation of the XPC promoter were examined. Apoptosis, cell proliferation and senescence were also quantified. XPC siRNA was used to determine that the responses seen were reliant on XPC induction.

RESULTS

Treatment with high-dose decitabine resulted in global demethylation, including the the shores of the XPC CpG island and significantly increased XPC mRNA expression. Lower, clinically relevant dose of decitabine also resulted in global demethylation including the CpG island shores and induced XPC in 50% of cell lines. Decitabine followed by DNA-damaging carboplatin treatment led to significantly higher XPC expression in 75% of melanoma cell lines tested. Combined sequential treatment also resulted in a greater apoptotic response in 75% of cell lines compared to carboplatin alone, and significantly slowed cell proliferation, with some melanoma cell lines going into senescence. Inhibiting the increased XPC using siRNA had a small but significant negative effect, indicating that XPC plays a partial role in the response to sequential decitabine and carboplatin.

CONCLUSIONS

Demethylation using decitabine increased XPC and apoptosis after sequential carboplatin. These results confirm that sequential decitabine and carboplatin requires further investigation as a combination treatment for melanoma.

The significance of intertumor and intratumor heterogeneity in liver cancer

Genomic analyses of primary liver cancer samples reveal a complex mutational landscape with vast intertumor and intratumor heterogeneity. Different primary liver tumors and subclones within each tumor display striking molecular and biological variations. Consequently, tumor molecular heterogeneity contributes to drug resistance and tumor relapse following therapy, which poses a substantial obstruction to improving outcomes of patients with liver cancer. There is an urgent need to the compositional and functional understanding of tumor heterogeneity. In this review, we summarize genomic and non-genomic diversities, which include stemness and microenvironmental causes of the functional heterogeneity of the primary liver cancer ecosystem. We discuss the importance and intricacy of intratumor heterogeneity in the context of cancer cell evolution. We also discuss methodologies applicable to determine intratumor heterogeneity and highlight the best-fit patient-derived in vivo and in vitro models to recapture the functional heterogeneity of primary liver cancer with the aim to improve future therapeutic strategies.

Taurine up-regulated gene 1 functions as a master regulator to coordinate glycolysis and metastasis in hepatocellular carcinoma

Cancer cells display altered glucose metabolism characterized by a preference for aerobic glycolysis. The aerobic glycolytic phenotype of hepatocellular carcinoma (HCC) is often correlated with tumor progression and poorer clinical outcomes. However, the issue of whether glycolytic metabolism influences metastasis in HCC remains unclear. In the current study, we showed that knockdown of taurine up-regulated gene 1 (TUG1) induces marked inhibition of cell migration, invasion, and glycolysis through suppression of microRNA (miR)-455-3p. MiR-455-3p, which is transcriptionally repressed by p21, directly targets the 3' untranslated region of adenosine monophosphate-activated protein kinase subunit beta 2 (AMPKβ2). The TUG1/miR-455-3p/AMPKβ2 axis regulates cell growth, metastasis, and glycolysis through regulation of hexokinase 2 (HK2). TUG1 is clearly associated with HK2 overexpression and unfavorable prognosis in HCC patients.

CONCLUSION

Our data collectively highlight that novel regulatory associations among TUG1, miR-455-3p, AMPKβ2, and HK2 are an important determinant of glycolytic metabolism and metastasis in HCC cells and support the potential utility of targeting TUG1/HK2 as a therapeutic strategy for HCC. (Hepatology 2018;67:188-203).

Metformin alleviates nickel-induced autophagy and apoptosis via inhibition of hexokinase-2, activating lipocalin-2, in human bronchial epithelial cells

Autophagy is an intracellular recycling and degradation process for regulating tumor progression, survival and drug resistance. Nickel compounds have been identified as human carcinogens. However, the role of nickel-induced autophagy in lung carcinogenesis has not yet been fully elucidated. In this study, we determined that hexokinase 2 (HK2), which phosphorylates glucose and regulates autophagy, is the key mediator in nickel-induced autophagy in lung bronchial epithelial cells. We attempted to investigate the effects of the antidiabetic drug metformin on HK2 expression and lung cancer chemoprevention. Our results showed that metformin decreases nickel-induced autophagy and activation of apoptosis through inhibition of HK2 gene, protein and activity. Furthermore, we demonstrated that lipocalin 2 (LCN2), which is released by neutrophils at sites of infection and inflammation is involved in HK2-driven autophagy pathway. Knockdown of endogenous HK2 and LCN2 by shRNA reduced nickel-elicited autophagy and apoptosis, illustrating that metabolic alteration and inflammatory action are important in nickel-elicited carcinogenesis. We also determined the association between nickel-induced autophagy and apoptosis. Inhibition of nickel-induced autophagy abolished apoptotic cell death in chloroquine-treated, shLC3 Beas-2B cells and Atg5^−/− MFFs. From TGCA database and immunohistochemistry analysis, HK2 and LCN2 expression increased in lung squamous cell carcinoma and their related adjacent normal tissues. Taken together, our results demonstrated that metformin alleviates NiCl₂-induced autophagy and apoptosis via HK2-driven LCN2 activation in human bronchial epithelial cells. This novel mechanism provides a strategy for targeting nickel-elicited lung cancer progression, as well as for preventing HK2 cumulative damage triggered by environmental carcinogens.

New Insights into the Epigenetics of Hepatocellular Carcinoma

Hepatocellular Carcinoma (HCC) is one of the most predominant malignancies with high fatality rate. This deadly cancer is rising at an alarming rate because it is quite resistant to radio- and chemotherapy. Different epigenetic mechanisms such as histone modifications, DNA methylation, chromatin remodeling, and expression of noncoding RNAs drive the cell proliferation, invasion, metastasis, initiation, progression, and development of HCC. These epigenetic alterations because of potential reversibility open way towards the development of biomarkers and therapeutics. The contribution of these epigenetic changes to HCC development has not been thoroughly explored yet. Further research on HCC epigenetics is necessary to better understand novel molecular-targeted HCC treatment and prevention. This review highlights latest research progress and current updates regarding epigenetics of HCC, biomarker discovery, and future preventive and therapeutic strategies to combat the increasing risk of HCC.