Glutaminolysis and carcinogenesis of oral squamous cell carcinoma

Improved Photodynamic Therapy Based on Glutaminase Blockage via Tumor Membrane Coated CB-839/IR-780 Nanoparticles

Photodynamic therapy (PDT) has promising applications. However, the lethal function of reactive oxygen species (ROS) produced during PDT is typically limited. This restriction is induced by oxygen shortage in the tumor microenvironment due to tumor cell hypermetabolism and reductive chemicals overexpression in tumor tissues. Glutamine (Gln) metabolism is crucial for malignancy development and is closely associated with redox. Herein, a novel nanoparticle (NP) named IRCB@M is constructed to boost PDT through dual effects. This NP simultaneously blocks aerobic respiration and inhibits cellular reduced substances by blocking the Gln metabolic pathway. Within the nanocomplex, a photosensitizer (IR-780) and a glutaminase inhibitor (CB-839) are self-assembled and then encapsulated by cancer cell membranes for homologous targeting. The Gln metabolism intervention relieves hypoxia and decreases the levels of nicotinamide adenine dinucleotide phosphate (NADPH) as well as reduced glutathione (GSH) in vitro and in vivo, which are the dual amplification effects on the IR-780-mediated lethal PDT. The antitumor effects against gastric cancer are ultimately evoked in vivo, thus offering a novel concept for enhancing PDT and other ROS-dependent therapeutic approaches.

Advanced progress of spatial metabolomics in head and neck cancer research

Head and neck cancer ranks as the sixth most prevalent malignancy, constituting 5 % of all cancer cases. Its inconspicuous onset often leads to advanced stage diagnoses, prompting the need for early detection to enhance patient prognosis. Currently, research into early diagnostic markers relies predominantly on genomics, proteomics, transcriptomics, and other methods, which, unfortunately, necessitate tumor tissue homogenization, resulting in the loss of temporal and spatial information. Emerging as a recent addition to the omics toolkit, spatial metabolomics stands out. This method conducts in situ mass spectrometry analyses on fresh tissue specimens while effectively preserving their spatiotemporal information. The utilization of spatial metabolomics in life science research offers distinct advantages. This article comprehensively reviews the progress of spatial metabolomics in head and neck cancer research, encompassing insights into cancer cell metabolic reprogramming. Various mass spectrometry imaging techniques, such as secondary ion mass spectrometry, stroma-assisted laser desorption/ionization, and desorption electrospray ionization, enable in situ metabolite analysis for head and neck cancer. Finally, significant emphasis is placed on the application of presently available techniques for early diagnosis, margin assessment, and prognosis of head and neck cancer.

Evaluation of Metabolomics as Diagnostic Targets in Oral Squamous Cell Carcinoma: A Systematic Review

In recent years, high-throughput technologies have facilitated the widespread use of metabolomics to identify biomarkers and targets for oral squamous cell carcinoma (OSCC). As a result, the primary goal of this systematic review is to identify and evaluate metabolite biomarkers and their pathways for OSCC that featured consistently across studies despite methodological variations. Six electronic databases (Medline, Cochrane, Web of Science, CINAHL, ProQuest, and Embase) were reviewed for the longitudinal studies involving OSCC patients and metabolic marker analysis (in accordance with PRISMA 2020). The studies included ranged from the inception of metabolomics in OSCC (i.e., 1 January 2007) to 30 April 2023. The included studies were then assessed for their quality using the modified version of NIH quality assessment tool and QUADOMICS. Thirteen studies were included after screening 2285 studies. The majority of the studies were from South Asian regions, and metabolites were most frequently derived from saliva. Amino acids accounted for more than quarter of the detected metabolites, with glutamate and methionine being the most prominent. The top dysregulated metabolites indicated dysregulation of six significantly enriched pathways including aminoacyl-tRNA biosynthesis, glutathione metabolism and arginine biosynthesis with the false discovery rate (FDR) <0.05. Finally, this review highlights the potential of metabolomics for early diagnosis and therapeutic targeting of OSCC. However, larger studies and standardized protocols are needed to validate these findings and make them a clinical reality.

Glutamine promotes the proliferation of epithelial cells via mTOR/S6 pathway in oral lichen planus

BACKGROUND

Although abnormal cell proliferation and apoptosis are associated with the pathogenesis of oral lichen planus (OLP), the exactly mechanism of which is not yet known. It has been reported that glutamine (Gln) can promote cell proliferation and inhibit apoptosis of various tumor cells. This study aims to evaluate the effect of Gln metabolism on the balance of proliferation and apoptosis in epithelial cells of OLP.

METHODS

Thirty human OLP specimens and 11 normal controls were stained by immunohistochemistry to detect the levels of proliferation and Gln metabolism related proteins. Then, the critical role of Gln in cell proliferation and apoptosis was determined by Gln deprivation or treatment with glutaminase inhibitor (CB-839) to intervene Gln metabolism in human gingival epithelial cells. Cell proliferation was detected using CCK8, p-mTOR and p-S6 proteins were detected using Western Blot, cell apoptosis and cell cycle were detected using flow cytometry, and cell stress was detected using immunofluorescence.

RESULTS

Compared with normal controls, OLP specimens showed higher levels of Ki-67 and Gln metabolism-related proteins, including Gln transporter (ASCT2), glutaminase (GLS), and pathway proteins (p-mTOR and p-S6). In vitro, Gln promoted cell proliferation and simultaneously upregulated the activity of mTOR/S6 pathway. Moreover, rapamycin, an mTOR pathway inhibitor, could effectively block the Gln-induced cell proliferation. MHY1485, an mTOR pathway agonist, could effectively reverse the decline of cell proliferation under Gln deprivation. In addition, inhibiting Gln metabolism caused the accumulation of intracellular radical oxygen species (ROS) and induced cell apoptosis. However, N-acetylcysteine reversed this state and then decreased cell apoptosis by eliminating intracellular ROS.

CONCLUSION

Gln metabolism is essential to maintain the balance of proliferation and apoptosis in oral epithelial cells, and inhibition of Gln metabolism may have a beneficial effect on OLP treatment.

Identification of Metabolism-Associated Biomarkers for Early and Precise Diagnosis of Oral Squamous Cell Carcinoma

The 5-year survival rate for oral squamous cell carcinoma (OSCC), one of the most common head and neck cancers, has not improved in the last 20 years. Poor prognosis of OSCC is the result of failure in early and precise diagnosis. Metabolic reprogramming, including the alteration of the uptake and utilisation of glucose, amino acids and lipids, is an important feature of OSCC and can be used to identify its biomarkers for early and precise diagnosis. In this review, we summarise how recent findings of rewired metabolic networks in OSCC have facilitated early and precise diagnosis of OSCC.

Targeting GLS1 to cancer therapy through glutamine metabolism

Glutamine metabolism is one of the hallmarks of cancers which is described as an essential role in serving as a major energy and building blocks supply to cell proliferation in cancer cells. Many malignant tumor cells always display glutamine addiction. The "kidney-type" glutaminase (GLS1) is a metabolism enzyme which plays a significant part in glutaminolysis. Interestingly, GLS1 is often overexpressed in highly proliferative cancer cells to fulfill enhanced glutamine demand. So far, GLS1 has been proved to be a significant target during the carcinogenesis process, and emerging evidence reveals that its inhibitors could provide a benefit strategy for cancer therapy. Herein, we summarize the prognostic value of GLS1 in multiple cancer type and its related regulatory factors which are associated with antitumor activity. Moreover, this review article highlights the remarkable reform of discovery and development for GLS1 inhibitors. On the basis of case studies, our perspectives for targeting GLS1 and development of GLS1 antagonist are discussed in the final part.

circBICD2 targets miR-149-5p/IGF2BP1 axis to regulate oral squamous cell carcinoma progression

BACKGROUND

Circular RNAs (circRNAs) are related to oral squamous cell carcinoma (OSCC) progression. circRNA bicaudal D cargo adaptor 2 (circBICD2) has been reported to be abnormally expressed in OSCC. However, the function and mechanism of this circRNA in OSCC progression remain largely unknown.

METHODS

circBICD2, microRNA-149-5p (miR-149-5p), and insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) abundances were examined via quantitative reverse transcription polymerase chain reaction or Western blot. The function of circBICD2 was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), colony formation, flow cytometry, wound healing, transwell, specific kits, Western blot, and xenograft analyses. Dual-luciferase reporter analysis and RNA immunoprecipitation were carried out to analyze the binding interaction.

RESULTS

circBICD2 expression was enhanced in OSCC tissues and cells. circBICD2 silence suppressed OSCC cell proliferation, migration, invasion, and glutaminolysis and facilitated apoptosis. miR-149-5p was targeted via circBICD2 and decreased in OSCC tissues and cells. miR-149-5p knockdown attenuated silence of circBICD2 on the influence of OSCC cell proliferation, apoptosis, migration, invasion, and glutaminolysis. IGF2BP1 was targeted via miR-149-5p, and circBICD2 could regulate IGF2BP1 via miR-149-5p. IGF2BP1 interference constrained OSCC cell proliferation, migration, invasion, and glutaminolysis and promoted apoptosis. circBICD2 silence reduced OSCC cell growth in xenograft model.

CONCLUSION

circBICD2 knockdown repressed OSCC cell proliferation, migration, invasion, and glutaminolysis and increased apoptosis via modulating miR-149-5p/IGF2BP1 axis, which might act as a potential target for OSCC treatment.

Membrane Transporters for Amino Acids as Players of Cancer Metabolic Rewiring

Cancer cells perform a metabolic rewiring to sustain an increased growth rate and compensate for the redox stress caused by augmented energy metabolism. The metabolic changes are not the same in all cancers. Some features, however, are considered hallmarks of this disease. As an example, all cancer cells rewire the amino acid metabolism for fulfilling both the energy demand and the changed signaling routes. In these altered conditions, some amino acids are more frequently used than others. In any case, the prerequisite for amino acid utilization is the presence of specific transporters in the cell membrane that can guarantee the absorption and the traffic of amino acids among tissues. Tumor cells preferentially use some of these transporters for satisfying their needs. The evidence for this phenomenon is the over-expression of selected transporters, associated with specific cancer types. The knowledge of the link between the over-expression and the metabolic rewiring is crucial for understanding the molecular mechanism of reprogramming in cancer cells. The continuous growth of information on structure-function relationships and the regulation of transporters will open novel perspectives in the fight against human cancers.

Glutaminases regulate glutathione and oxidative stress in cancer

Targeted therapies against cancer have improved both survival and quality of life of patients. However, metabolic rewiring evokes cellular mechanisms that reduce therapeutic mightiness. Resistant cells generate more glutathione, elicit nuclear factor erythroid 2-related factor 2 (NRF2) activation, and overexpress many anti-oxidative genes such as superoxide dismutase, catalase, glutathione peroxidase, and thioredoxin reductase, providing stronger antioxidant capacity to survive in a more oxidative environment due to the sharp rise in oxidative metabolism and reactive oxygen species generation. These changes dramatically alter tumour microenvironment and cellular metabolism itself. A rational design of therapeutic combination strategies is needed to flatten cellular homeostasis and accomplish a drop in cancer development. Context-dependent glutaminase isoenzymes show oncogenic and tumour suppressor properties, being mainly associated to MYC and p53, respectively. Glutaminases catalyze glutaminolysis in mitochondria, regulating oxidative phosphorylation, redox status and cell metabolism for tumour growth. In addition, the substrate and product of glutaminase reaction, glutamine and glutamate, respectively, can work as signalling molecules moderating redox and bioenergetic pathways in cancer. Novel synergistic approaches combining glutaminase inhibition and redox-dependent modulation are described in this review. Pharmacological or genetic glutaminase regulation along with oxidative chemotherapy can help to improve the design of combination strategies that escalate the rate of therapeutic success in cancer patients.

ASCT2 overexpression is associated with poor survival of OSCC patients and ASCT2 knockdown inhibited growth of glutamine-addicted OSCC cells

Background

Alanine‐serine‐cysteine transporter 2 (ASCT2), a major glutamine transporter, is essential for cell growth and tumor development in a variety of cancers. However, the clinicopathological significance and pathological role of ASCT2 in OSCC (oral squamous cell carcinoma) lesions remain unclear.

Methods

Sections from 89 OSCC patients and 10 paracancerous tissue controls were stained by immunohistochemistry (IHC) to detect the expression of ASCT2, glutaminase, and Ki‐67. Survival analysis was carried out to determine the predictive value of ASCT2 expression using the log‐rank test. Moreover, the critical role of ASCT2 in tumor growth was determined by a series of in vitro and in vivo assays. Cell Counting Kit‐8 (CCK8), Western Blotting (WB), Reactive Oxygen Species (ROS), and Glutathione (GSH) detection were applied to explore the molecular mechanism of ASCT2 involvement in tumor development.

Results

In OSCC lesions, ASCT2 expression was significantly increased and associated with cell proliferation index (Ki‐67) and GLS expression. Moreover, survival analysis showed that OSCC patients with high ASCT2 expression had lower overall survival (P = 0.0365). In OSCC cell lines, the high level of ASCT2 was inherent and related to the glutamine addiction of tumor cells. In vitro and in vivo functional experiments revealed that targeted silencing of ASCT2 can effectively inhibit OSCC cell proliferation and tumor growth. Mechanistically, targeting ASCT2 knockdown reduced glutamine uptake and intracellular GSH levels, which contribute to the accumulation of ROS and induce apoptosis in OSCC cells.

Conclusion

ASCT2 is a significant factor for predicting overall survival in patients with OSCC, and targeting ASCT2 to inhibit glutamine metabolism may be a promising strategy for OSCC treatment.

Alterations in plasma concentrations of energy-balance-related metabolites in patients with lung, or head & neck, cancers: Effects of radiotherapy

We investigated the alterations in the plasma concentrations of energy-balance-related metabolites in patients with lung (LC) or head & neck (HNC) cancer and the changes on these parameters induced by radiotherapy. The study was conducted in 33 patients with non-small cell LC and 28 patients with HNC. We analyzed the concentrations of 17 metabolites involved in glycolysis, citric acid cycle and amino acid metabolism using targeted gas chromatography coupled to quadrupole time-of-flight mass spectrometry. For comparison, a control group of 50 healthy individuals was included in the present study. Patients with LC or HNC had significant alterations in the plasma levels of several energy-balance-related metabolites. Radiotherapy partially normalized these alterations in patients with LC, but not in those with HNC. The measurement of plasma glutamate concentration was an excellent predictor of the presence of LC or HNC, with sensitivity >90% and specificity >80%. Also, associations with disease prognosis were observed with plasma glutamate, amino acids and β-hydroxybutyrate concentrations. SIGNIFICANCE: This study analyzed the changes produced in the plasma concentrations of energy-balance-related metabolites in patients with lung cancer or head and neck cancer. The results obtained identified glutamate as the parameter with the highest discrimination capacity between patients and the control group. The relationships between various metabolites and clinical outcomes were also analyzed. These results extend the knowledge of metabolic alterations in cancer, thus facilitating the search for biomarkers and therapeutic targets.

Low-Concentration PTX And RSL3 Inhibits Tumor Cell Growth Synergistically By Inducing Ferroptosis In Mutant p53 Hypopharyngeal Squamous Carcinoma

Introduction

RSL3-induced ferroptosis is a cell death pathway dependent upon intracellular iron and is characterized by accumulation of lipid hydroperoxides. Glutaminolysis, a glutamine-fueled intracellular metabolic pathway, is an essential pathway of ferroptosis in cancer cells. Recent findings showed low-concentration paclitaxel (PTX) could inhibit cell death by upregulating p53 expression; downregulating glutaminolysis-related genes.

Methods

The therapeutic effect of RSL3 plus low-concentration PTX combination therapy was investigated in HPSCC cells harboring mutant p53 (mtp53). Relative cell viability, ferroptosis-specific lipid peroxidation and relevant protein expression were evaluated.

Results

We demonstrated that neither PTX nor RSL3 in low concentration caused significant cell death; however, the combination therapy is shown to induce ferroptosis and significant cell death in mtp53 HPSCC. We discovered that low-concentration PTX enhanced the RSL3-induced ferroptosis by upregulating mtp53 expression. Furthermore, mtp53-mediated transcriptional regulation of SLC7A11 could be the key determinant.

Discussion

Although gain-of-function of p53 variants remains to be characterized, our findings provide new insight into the synergistical cell death by regulating ferroptosis and p53.

Targeting cellular metabolism to reduce head and neck cancer growth

Head and neck squamous cell carcinoma (HNSCC) presents a major public health concern because of delayed diagnosis and poor prognosis. Malignant cells often reprogram their metabolism in order to promote their survival and proliferation. Aberrant glutaminase 1 (GLS1) expression enables malignant cells to undergo increased glutaminolysis and utilization of glutamine as an alternative nutrient. In this study, we found a significantly elevated GLS1 expression in HNSCC, and patients with high expression levels of GLS1 experienced shorter disease-free periods after therapy. We hypothesized that the GLS1 selective inhibitor, bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide (BPTES), which curtails cells' glutamine consumption, may inhibit HNSCC cell growth. Our results support the idea that BPTES inhibits HNSCC growth by inducing apoptosis and cell cycle arrest. Considering that metformin can reduce glucose consumption, we speculated that metformin would enhance the anti-neoplasia effect of BPTES by suppressing malignant cells' glucose utilization. The combination of both compounds exhibited an additive inhibitory effect on cancer cell survival and proliferation. All of our data suggest that GLS1 is a promising therapeutic target for HNSCC treatment. Combining BPTES with metformin might achieve improved anti-cancer effects in HNSSC, which sheds light on using novel therapeutic strategies by dually targeting cellular metabolism.

iTRAQ-Based Quantitative Proteomics Approach Identifies Novel Diagnostic Biomarkers That Were Essential for Glutamine Metabolism and Redox Homeostasis for Gastric Cancer

PURPOSE

To screen the novel biomarkers for gastric cancer and to determine the values of glutaminase 1 (GLS1) and gamma-glutamylcyclotransferase (GGCT) for detecting gastric cancer.

EXPERIMENTAL DESIGN

A discovery group of four paired gastric cancer tissue samples are labeled with Isobaric tag for relative and absolute quantitation agents and identified with LC-ESI-MS/MS. A validation group of 168 gastric cancer samples and 30 healthy controls are used to validate the expression of GLS1 and GGCT.

RESULTS

Four hundred and thirty-one proteins are found differentially expressed in gastric cancer tissues. Of these proteins, GLS1 and GGCT are found overexpressed in gastric cancer patients, with sensitivity of 75.6% (95% CI: 69-82.2%) and specificity of 81% (95% CI: 75-87%) for GLS1, and with sensitivity of 63.1% (95% CI: 55.7-71.5%) and specificity of 60.7% (95% CI: 53.3-68.2%) for GGCT. The co-expression of GLS1 and GGCT in gastric cancer tissues has sensitivity of 78.1% (95% CI: 70.1-86.1%) and specificity of 86.5% (95% CI: 79.5-93.4%). Moreover, both GLS1 and GGCT present higher expression of 82.6% (95% CI: 68.5-99.4%) and 73.9% (95% CI: 54.5-93.3%) in lymph node metastasis specimen than those in non-lymph node metastasis specimen. The areas under ROC curves are up to 0.734 for the co-expression of GLS1 and GGCT in gastric cancer. The co-expression of GLS1 and GGCT is strongly associated with histological grade, lymph node metastasis, and TNM stage Ⅲ/Ⅳ.

CONCLUSIONS AND CLINICAL RELEVANCE

The present study provides the quantitative proteomic analysis of gastric cancer tissues to identify prognostic biomarkers of gastric cancer. The co-expression level of GLS1 and GGCT is of great clinical value to serve as diagnostic and therapeutic biomarkers for early gastric cancer.

The elevated glutaminolysis of bladder cancer and T cells in a simulated tumor microenvironment contributes to the up-regulation of PD-L1 expression by interferon-γ

Background

Metabolic reprogramming occurs in the tumor microenvironment and influences the survival and function of tumor and immune cells. Interferon-γ (IFN-γ) produced by T cells up-regulates PD-L1 expression in tumors. However, reports regarding the relationship between nutrient metabolism and the up-regulation of PD-L1 expression are lacking.

Materials and methods

In this paper, we analyzed the metabolic changes in T cells and bladder cancer cells in a simulated tumor microenvironment to provide evidence regarding their relevance to PD-L1 up-regulation.

Results

The glutaminolysis was increased in both activated T cells and glucose-deprived T cells. IFN-γ production by T cells was decreased in a glucose-free medium and severely decreased when cells were simultaneously deprived of glutamine. Furthermore, the glutaminolysis of the bladder cancer cells under glucose deprivation exhibited a compensatory elevation. The glucose concentration of T cells co-cultured with bladder cancer cells was decreased and T cell proliferation was reduced, but IFN-γ production and glutaminolysis were increased. However, in bladder cancer cells, the elevation in glutaminolysis under co-culture conditions did not compensate for glucose deprivation because the glucose concentration in the culture medium did not significantly differ between the cultures with and without T cells. Our data also show that inhibiting glutamine metabolism in bladder cancer cells could reduce the elevation in PD-L1 expression induced by IFN-γ.

Conclusion

In a simulated tumor microenvironment, elevated glutaminolysis may play an essential role in IFN-γ production by T cells, ultimately improving the high PD-L1 expression, and also directly contributing to producing more PD-L1 in bladder cancer cells.

Non-apoptotic cell death in malignant tumor cells and natural compounds

Traditional cancer therapy is mainly targeting on enhancing cell apoptosis, however, it is well established that many cancer cells are chemo-resistant and defective in apoptosis induction. Therefore, it may have important therapeutic implications to exploit some novel natural compounds based on non-apoptotic programmed cell death. Currently, accumulating evidence shows that the compounds from nature source can induce non-apoptotic programmed cell death in cancer cells, and therefore these natural compounds have gained a great promise for the future anticancer therapeutics. In this review, we will concentrate our efforts on the latest developments regarding major forms of non-apoptotic programmed cell death--autophagic cell death, necroptosis, ferroptosis, pyroptosis, glutamoptosis and exosome-associated cell death. Our increased understanding of the role of natural compounds in regulating non-apoptotic programmed cell death will hopefully provide prospective strategies for cancer therapy.

Glutamine Transport and Mitochondrial Metabolism in Cancer Cell Growth

The concept that cancer is a metabolic disease is now well acknowledged: many cancer cell types rely mostly on glucose and some amino acids, especially glutamine for energy supply. These findings were corroborated by overexpression of plasma membrane nutrient transporters, such as the glucose transporters (GLUTs) and some amino acid transporters such as ASCT2, LAT1, and ATB^0,+, which became promising targets for pharmacological intervention. On the basis of their sodium-dependent transport modes, ASCT2 and ATB0⁺ have the capacity to sustain glutamine need of cancer cells; while LAT1, which is sodium independent will have the role of providing cancer cells with some amino acids with plausible signaling roles. According to the metabolic reprogramming of many types of cancer cells, glucose is mainly catabolized by aerobic glycolysis in tumors, while the fate of Glutamine is completed at mitochondrial level where the enzyme Glutaminase converts Glutamine to Glutamate. Glutamine rewiring in cancer cells is heterogeneous. For example, Glutamate is converted to α-Ketoglutarate giving rise to a truncated form of Krebs cycle. This reprogrammed pathway leads to the production of ATP mainly at substrate level and regeneration of reducing equivalents needed for cells growth, redox balance, and metabolic energy. Few studies on hypothetical mitochondrial transporter for Glutamine are reported and indirect evidences suggested its presence. Pharmacological compounds able to inhibit Glutamine metabolism may represent novel drugs for cancer treatments. Interestingly, well acknowledged targets for drugs are the Glutamine transporters of plasma membrane and the key enzyme Glutaminase.

Real-time monitoring system for evaluating the acid-producing activity of oral squamous cell carcinoma cells at different environmental pH

This study aimed to establish a real-time monitoring system for evaluating the acid-producing activity of cells and the effects of microenvironmental pH on their metabolism. Oral squamous cell carcinoma (HSC-2, HSC-3) and normal (HaCaT) cells were used. Their acid-producing activity from glucose, glutamine, and glutamate was monitored at various pH values using a pH stat system. Their production of lactic acid and ammonia was also measured. The acid-producing activity was monitored successfully. Both the cancer and normal cells produced acids from glucose, glutamine, and glutamate. All of the cells decreased their acid-producing activity as the environmental pH fell, but in glucose-derived acid-producing activity the cancer cells were more acid-tolerant than HaCaT cells. In the cancer cells, the proportion of lactic acid among all acids produced from glucose at the acidic environment tended to be higher than that in HaCaT cells. All of the cells produced ammonia from glutamine, while only HaCaT cells produced ammonia from glutamate. We established a real-time monitoring system for evaluating the acid-producing activity of cells. Our results suggest that the cancer cells possess acid-tolerant glucose metabolism with a tendency of metabolic shift to lactic acid production at acidic pH and they metabolise glutamate without ammonia production.

Mitochondria in Cancer Energy Metabolism: Culprits or Bystanders?

Cancer is a disease characterized by uncontrolled growth. Metabolic demands to sustain rapid proliferation must be compelling since aerobic glycolysis is the first as well as the most commonly shared characteristic of cancer. During the last decade, the significance of metabolic reprogramming of cancer has been at the center of attention. Nonetheless, despite all the knowledge gained on cancer biology, the field is not able to reach agreement on the issue of mitochondria: Are damaged mitochondria the cause for aerobic glycolysis in cancer? Warburg proposed the damaged mitochondria theory over 80 years ago; the field has been testing the theory equally long. In this review, we will discuss alterations in metabolic fluxes of cancer cells, and provide an opinion on the damaged mitochondria theory.

Integrated network analysis and logistic regression modeling identify stage-specific genes in Oral Squamous Cell Carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is associated with substantial mortality and morbidity but, OSCC can be difficult to detect at its earliest stage due to its molecular complexity and clinical behavior. Therefore, identification of key gene signatures at an early stage will be highly helpful.

METHODS

The aim of this study was to identify key genes associated with progression of OSCC stages. Gene expression profiles were classified into cancer stage-related modules, i.e., groups of genes that are significantly related to a clinical stage. For prioritizing the candidate genes, analysis was further restricted to genes with high connectivity and a significant association with a stage. To assess predictive power of these genes, a classification model was also developed and tested by 5-fold cross validation and on an independent dataset.

RESULTS

The identified genes were enriched for significant processes and functional pathways, and various genes were found to be directly implicated in OSCC. Forward and stepwise, multivariate logistic regression analyses identified 13 key genes whose expression discriminated early- and late-stage OSCC with predictive accuracy (area under curve; AUC) of ~0.81 in a 5-fold cross-validation strategy.

CONCLUSIONS

The proposed network-driven integrative analytical approach can identify multiple genes significantly related to an OSCC stage; the classification model that is developed with these genes may help to distinguish cancer stages. The proposed genes and model hold promise for monitoring of OSCC stage progression, and our findings may facilitate cancer detection at an earlier stage, resulting in improved treatment outcomes.