Tumor metabolism, cancer cell transporters, and microenvironmental resistance

Modulating macrophage-mediated programmed cell removal: An attractive strategy for cancer therapy

Macrophage-mediated programmed cell removal (PrCR) is crucial for the identification and elimination of needless cells that maintain tissue homeostasis. The efficacy of PrCR depends on the balance between pro-phagocytic "eat me" signals and anti-phagocytic "don't eat me" signals. Recently, a growing number of studies have shown that tumourigenesis and progression are closely associated with PrCR. In the tumour microenvironment, PrCR activated by the "eat me" signal is counterbalanced by the "don't eat me" signal of CD47/SIRPα, resulting in tumour immune escape. Therefore, targeting exciting "eat me" signalling while simultaneously suppressing "don't eat me" signalling and eventually inducing macrophages to produce effective PrCR will be a very attractive antitumour strategy. Here, we comprehensively review the functions of PrCR-activating signal molecules (CRT, PS, Annexin1, SLAMF7) and PrCR-inhibiting signal molecules (CD47/SIRPα, MHC-I/LILRB1, CD24/Siglec-10, SLAMF3, SLAMF4, PD-1/PD-L1, CD31, GD2, VCAM1), the interactions between these molecules, and Warburg effect. In addition, we highlight the molecular regulatory mechanisms that affect immune system function by exciting or suppressing PrCR. Finally, we review the research advances in tumour therapy by activating PrCR and discuss the challenges and potential solutions to smooth the way for tumour treatment strategies that target PrCR.

Exploring the Redox and pH Dimension of Carbonic Anhydrases in Cancer: A Focus on Carbonic Anhydrase 3

Significance: Both redox and pH are important regulatory processes that underpin cell physiological functions, in addition to influencing cancer cell development and tumor progression. The thioredoxin (Trx) and glutathione redox systems and the carbonic anhydrase (CA) proteins are considered key regulators of cellular redox and pH, respectively, with components of the Trx system and CAs regarded as cancer therapeutic targets. However, the redox and pH axis in cancer cells is an underexplored topic of research. Recent Advances: Structural studies of a CA family member, CA3, localized two of its five cysteine residues to the protein surface. Redox-regulated modifications to CA3 have been identified, including glutathionylation. CA3 has been shown to bind to other proteins, including B cell lymphoma-2-associated athanogene 3, and squalene epoxidase, which can modulate autophagy and proinflammatory signaling, respectively, in cancer cells. Critical Issues: CA3 has also been associated with epithelial-mesenchymal transition processes, which promote cancer cell metastasis, whereas CA3 overexpression activates the phosphatidylinositol-3 kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway, which upregulates cell growth and inhibits autophagy. It is not yet known if CA3 modulates cancer progression through its reported antioxidant functions. Future Directions: CA3 is one of the least studied CA isozymes. Further studies are required to assess the cellular antioxidant role of CA3 and its impact on cancer progression. Identification of other binding partners is also required, including whether CA3 binds to Trx in human cells. The development of specific CA3 inhibitors will facilitate these functional studies and allow CA3 to be investigated as a cancer therapeutic target.

Active Anchoring Stimuli-Responsive Nano-Craft to Relieve Pulmonary Vasoconstriction by Targeting Smooth Muscle Cell for Hypoxic Pulmonary Hypertension Treatment

Recently, nanotechnology-based drug delivery platforms in treating pulmonary arterial hypertension (PAH) have gradually emerged. However, large mechanical stress and shear stress in blood vessels greatly affect the retention of nanopreparative materials at lesion sites, severely limiting nanotechnology-based drug delivery. Herein, a stimuli-responsive nanocraft is rationally designed by actively anchoring E-selectin overexpressed on pulmonary arterial endothelial cells (PAECs), under hypoxic conditions, allowing effective accumulation and retention of the drug at the lesion site. Briefly, a nitrobenzene group is incorporated into the framework of a nanocarrier, and then it is simultaneously linked with chitosan. Additionally, the surface of the nanocarrier with sialic acid (SA) and encapsulated the clinically used drug ambrisentan (Am), which enables the anchoring of E-selectin and subsequent drug delivery is modifed. This system facilitates intercellular transport to pulmonary artery smooth muscle cells (PASMCs) when targeting PAECs and specifically responds to a reductive hypoxic microenvironment with elevated nitroreductase in PASMCs. Moreover, compared with free Am, nanoencapsulation and SA-PEG2000-NH2 prolong the blood circulation time, achieving better therapeutic outcomes in preventing vascular remodeling and reversing systolic dysfunction. The originality and contribution of this work reveal the promising value of this pulmonary arterial anchoring stimuli-responsive nanocraft as a novel therapeutic strategy for satisfactory PAH treatment.

Critical role of miR-21/exosomal miR-21 in autophagy pathway

Activation of autophagy, a process of cellular stress response, leads to the breakdown of proteins, organelles, and other parts of the cell in lysosomes, and can be linked to several ailments, such as cancer, neurological diseases, and rare hereditary syndromes. Thus, its regulation is very carefully monitored. Transcriptional and post-translational mechanisms domestically or in whole organisms utilized to control the autophagic activity, have been heavily researched. In modern times, microRNAs (miRNAs) are being considered to have a part in post-translational orchestration of the autophagic activity, with miR-21 as one of the best studied miRNAs, it is often more than expressed in cancer cells. This regulatory RNA is thought to play a major role in a plethora of processes and illnesses including growth, cancer, cardiovascular disease, and inflammation. Different studies have suggested that a few autophagy-oriented genes, such as PTEN, Rab11a, Atg12, SIPA1L2, and ATG5, are all targeted by miR-21, indicating its essential role in the regulation.

Bacteriophage-encoded 24B_1 molecule resembles herpesviral microRNAs and plays a crucial role in the development of both the virus and its host

The 24B_1 small non-coding RNA molecule has been identified in Escherichia coli after induction of Shiga toxin-converting bacteriophage Φ24B. In this work, we focused on its direct role during phage and bacterial host development. We observed that in many aspects, this phage sRNA resembles herpesviral microRNAs. Similar to microRNAs, the mature 24B_1 is a short molecule, consisting of just 20 nucleotides. It is generated by cleaving the 80-nt long precursor transcript, and likely it undergoes a multi-step maturation process in which the Hfq protein plays an important role, as confirmed by demonstration of its binding to the 24B_1 precursor, but not to the 24B_1 mature form. Moreover, 24B_1 plays a significant role in maintaining the prophage state and reprogramming the host's energy metabolism. We proved that overproduction of this molecule causes the opposite physiological effects to the mutant devoid of the 24B_1 gene, and thus, favors the lysogenic pathway. Furthermore, the 24B_1 overrepresentation significantly increases the efficiency of expression of phage genes coding for proteins CI, CII, and CIII which are engaged in the maintenance of the prophage. It seems that through binding to mRNA of the sdhB gene, coding for the succinate dehydrogenase subunit, the 24B_1 alters the central carbon metabolism and causes a drop in the ATP intracellular level. Interestingly, a similar effect, called the Warburg switch, is caused by herpesviral microRNAs and it is observed in cancer cells. The advantage of the Warburg effect is still unclear, however, it was proposed that the metabolism of cancer cells, and all rapidly dividing cells, is adopted to convert nutrients such as glucose and glutamine faster and more efficiently into biomass. The availability of essential building blocks, such as nucleotides, amino acids, and lipids, is crucial for effective cell proliferation which in turn is essential for the prophage and its host to stay in the lysogenic state.

Targeting anticancer immunity in oral cancer: Drugs, products, and nanoparticles

Oral cavity carcinomas are the most frequent malignancies among head and neck malignancies. Oral tumors include not only oral cancer cells with different potency and stemness but also consist of diverse cells, containing anticancer immune cells, stromal and also immunosuppressive cells that influence the immune system reactions. The infiltrated T and natural killer (NK) cells are the substantial tumor-suppressive immune compartments in the tumor. The infiltration of these cells has substantial impacts on the response of tumors to immunotherapy, chemotherapy, and radiotherapy. Nevertheless, cancer cells, stromal cells, and some other compartments like regulatory T cells (Tregs), macrophages, and myeloid-derived suppressor cells (MDSCs) can repress the immune responses against malignant cells. Boosting anticancer immunity by inducing the immune system or repressing the tumor-promoting cells is one of the intriguing approaches for the eradication of malignant cells such as oral cancers. This review aims to concentrate on the secretions and interactions in the oral tumor immune microenvironment. We review targeting tumor stroma, immune system and immunosuppressive interactions in oral tumors. This review will also focus on therapeutic targets and therapeutic agents such as nanoparticles and products with anti-tumor potency that can boost anticancer immunity in oral tumors. We also explain possible future perspectives including delivery of various cells, natural products and drugs by nanoparticles for boosting anticancer immunity in oral tumors.

Fibroblast Activation Protein and Glycolysis in Lymphoma Diagnosis: Comparison of 68Ga-FAPI PET/CT and 18F-FDG PET/CT

Our objective was to compare the diagnostic performance of 68Ga-labeled fibroblast activation protein (FAP) inhibitor (FAPI) and 18F-labeled FDG PET/CT in diagnosing lymphomas and to characterize the influence of FAP and glycolytic markers on tracer uptake by involved lesions. Methods: Participants with different lymphoma subtypes who were prospectively recruited from May 2020 to December 2021 underwent 68Ga-FAPI and 18F-FDG PET/CT. Immunohistochemistry was performed to evaluate FAP, hexokinase 2, and glucose transporter 1 (GLUT1) expression, and the paired-samples t test and Wilcoxon signed-rank test were used to compare parameters. The correlation between the immunochemistry results and tracer uptake was determined by the Spearman rank correlation coefficient. Results: In total, 186 participants (median age, 52 y [interquartile range, 41-64 y]; 95 women) were included. Dual-tracer imaging produced 3 types of imaging profiles. 18F-FDG PET possessed a higher staging accuracy (98.4%) than 68Ga-FAPI PET (86.0%). In 5,980 lymphoma lesions, 18F-FDG PET/CT detected more nodal (4,624 vs. 2,196) and extranodal (1,304 vs. 845) lesions than 68Ga-FAPI PET/CT. Additionally, 52 68Ga-FAPI-positive/18F-FDG-negative lesions and 2,939 68Ga-FAPI-negative/18F-FDG-positive lesions were observed. In many lymphoma subtypes, semiquantitative evaluation revealed no significant differences in SUVmax or target-to-liver ratios between 68Ga-FAPI and 18F-FDG PET/CT (P > 0.05). Interestingly, GLUT1 and hexokinase 2 were overexpressed both in lymphoma cells and in the tumor microenvironment, whereas FAP was expressed only in stromal cells. FAP and GLUT1 expression correlated positively with 68Ga-FAPI SUVmax (r = 0.622, P = 0.001) and 18F-FDG SUVmax (r = 0.835, P < 0.001), respectively. Conclusion: 68Ga-FAPI PET/CT was inferior to 18F-FDG PET/CT in diagnosing lymphomas with low FAP expression. However, the former may supplement the latter and help reveal the molecular profile of lymphomas.

Detection of tissue pH with quantitative chemical exchange saturation transfer magnetic resonance imaging

Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) has emerged as a novel means for sensitive detection of dilute labile protons and chemical exchange rates. By sensitizing to pH-dependent chemical exchange, CEST MRI has shown promising results in monitoring tissue statuses such as pH changes in disorders like acute stroke, tumor, and acute kidney injury. This article briefly reviews the basic principles for CEST imaging and quantitative measures, from the simplistic asymmetry analysis to multipool Lorentzian decoupling and quasi-steady-state reconstruction. In particular, the advantages and limitations of commonly used quantitative approaches for CEST applications are discussed.

The prognostic signature based on glycolysis-immune related genes for acute myeloid leukemia patients

Acute myeloid leukemia (AML) is widely considered an immunoresponsive malignancy. However, potential association between glycolysis-immune related genes and AML patients' prognosis has been seldom studied. AML-related data was downloaded from TCGA and GEO databases. We grouped patients according to Glycolysis status, Immune Score and combination analysis, basing on which overlapped differentially expressed genes (DEGs) were identified. The Risk Score model was then established. The results showed that totally 142 overlapped genes were probably correlated with glycolysis-immunity in AML patients, among which 6 optimal genes were screened to construct Risk Score. High Risk Score was an independent poor prognostic factor for AML. In conclusion, we established a relatively reliable prognostic signature of AML based on glycolysis-immunity related genes, including METTL7B, HTR7, ITGAX, TNNI2, SIX3 and PURG.

Roadmap to Pyruvate Kinase M2 Modulation - A Computational Chronicle

Pyruvate kinase M2 (PKM2) has surfaced as a potential target for anti-cancer therapy. PKM2 is known to be overexpressed in the tumor cells and is a critical metabolic conduit in supplying the augmented bioenergetic demands of the recalcitrant cancer cells. The presence of PKM2 in structurally diverse tetrameric as well as dimeric forms has opened new avenues to design novel modulators. It is also a truism to state that drug discovery has advanced significantly from various computational techniques like molecular docking, virtual screening, molecular dynamics, and pharmacophore mapping. The present review focuses on the role of computational tools in exploring novel modulators of PKM2. The structural features of various isoforms of PKM2 have been discussed along with reported modulators. An extensive analysis of the structure-based and ligand- based in silico methods aimed at PKM2 modulation has been conducted with an in-depth review of the literature. The role of advanced tools like QSAR and quantum mechanics has been established with a brief discussion of future perspectives.

The Involvement of Long Non-Coding RNAs in Glutamine-Metabolic Reprogramming and Therapeutic Resistance in Cancer

Metabolic alterations that support the supply of biosynthetic molecules necessary for rapid and sustained proliferation are characteristic of cancer. Some cancer cells rely on glutamine to maintain their energy requirements for growth. Glutamine is an important metabolite in cells because it not only links to the tricarboxylic acid cycle by producing α-ketoglutarate by glutaminase and glutamate dehydrogenase but also supplies other non-essential amino acids, fatty acids, and components of nucleotide synthesis. Altered glutamine metabolism is associated with cancer cell survival, proliferation, metastasis, and aggression. Furthermore, altered glutamine metabolism is known to be involved in therapeutic resistance. In recent studies, lncRNAs were shown to act on amino acid transporters and glutamine-metabolic enzymes, resulting in the regulation of glutamine metabolism. The lncRNAs involved in the expression of the transporters include the abhydrolase domain containing 11 antisense RNA 1, LINC00857, plasmacytoma variant translocation 1, Myc-induced long non-coding RNA, and opa interacting protein 5 antisense RNA 1, all of which play oncogenic roles. When it comes to the regulation of glutamine-metabolic enzymes, several lncRNAs, including nuclear paraspeckle assembly transcript 1, XLOC_006390, urothelial cancer associated 1, and thymopoietin antisense RNA 1, show oncogenic activities, and others such as antisense lncRNA of glutaminase, lincRNA-p21, and ataxin 8 opposite strand serve as tumor suppressors. In addition, glutamine-dependent cancer cells with lncRNA dysregulation promote cell survival, proliferation, and metastasis by increasing chemo- and radio-resistance. Therefore, understanding the roles of lncRNAs in glutamine metabolism will be helpful for the establishment of therapeutic strategies for glutamine-dependent cancer patients.

Spatial Transcriptomics-Based Identification of Molecular Markers for Nanomedicine Distribution in Tumor Tissue

The intratumoral accumulation of nanomedicine has been considered a passive process, referred to as the enhanced permeability and retention effect. Recent studies have suggested that the tumor uptake of nanomedicines follows an energy-dependent pathway rather than being a passive process. Herein, to explore the factor candidates that are associated with nanomedicine tumor uptake, a molecular marker identification platform is developed by integrating microscopic fluorescence images of a nanomedicine distribution with spatial transcriptomics information. When this approach is applied to PEGylated liposomes, molecular markers related to hypoxia, glycolysis, and apoptosis can be identified as being related to the intratumoral distribution of the nanomedicine. It is expected that the method can be applied to explain the distribution of a wide range of nanomedicines and that the data obtained from this analysis can enhance the precise utilization of nanomedicines.

Construction of a prognostic model of colon cancer patients based on metabolism-related lncRNAs

Background

Many studies have shown that metabolism-related lncRNAs may play an important role in the pathogenesis of colon cancer. In this study, a prognostic model for colon cancer patients was constructed based on metabolism-related lncRNAs.

Methods

Both transcriptome data and clinical data of colon cancer patients were downloaded from the TCGA database, and metabolism-related genes were downloaded from the GSEA database. Through differential expression analysis and Pearson correlation analysis, long non-coding RNAs (lncRNAs) related to colon cancer metabolism were obtained. CRC patients were divided into training set and verification set at the ratio of 2:1. Based on the training set, univariate Cox regression analysis was utilized to determine the prognostic differential expression of metabolic-related lncRNAs. The Optimal lncRNAs were obtain by Lasso regression analysis, and a risk model was built to predict the prognosis of CRC patients. Meanwhile, patients were divided into high-risk and low-risk groups and a survival curve was drawn accordingly to determine whether the survival rate differs between the two groups. At the same time, subgroup analysis evaluated the predictive performance of the model. We combined clinical indicators with independent prognostic significance and risk scores to construct a nomogram. C index and the calibration curve, DCA clinical decision curve and ROC curve were obtained as well. The above results were all verified using the validation set. Finally, based on the CIBERSORT analysis method, the correlation between lncRNAs and 22 tumor-infiltrated lymphocytes was explored.

Results

By difference analysis, 2491 differential lncRNAs were obtained, of which 226 were metabolic-related lncRNAs. Based on Cox regression analysis and Lasso results, a multi-factor prognostic risk prediction model with 13 lncRNAs was constructed. Survival curve results suggested that patients with high scores and have a poorer prognosis than patients with low scores (P<0.05). The area under the ROC curve (AUC) for the 3-year survival and 5-year survival were 0.768 and 0.735, respectively. Cox regression analysis showed that age, distant metastasis and risk scores can be used as independent prognostic factors. Then, a nomogram including age, distant metastasis and risk scores was built. The C index was 0.743, and the ROC curve was drawn to obtain the AUC of the 3-year survival and the 5-year survival, which were 0.802 and 0.832, respectively. The above results indicated that the nomogram has a good predictive effect. Enrichment analysis of KEGG pathway revealed that differential lncRNAs may be related to chemokines, amino acid and sugar metabolism, NOD-like receptor and Toll-like receptor activation as well as other pathways. Finally, the analysis results based on the CIBERSORT algorithm showed that the lncRNAs used to construct the model had a strong polarized correlation with B cells, CD8+T cells and M0 macrophages.

Conclusion

13 metabolic-related lncRNAs affecting the prognosis of CRC were screened by bioinformatics methods, and a prognostic risk model was constructed, laying a solid foundation for the research of metabolic-related lncRNAs in CRC.

Rational Design of Oxazolidine-Based Red Fluorescent pH Probe for Simultaneous Imaging Two Subcellular Organelles

A reversible pH-responsive fluorescent probe, BP, was rationally designed and synthesized, based on protonation and deprotonation gave rise to oxazolidine ring open and close. The fluorescence response of BP against pH ranges from 3.78 to 7.54, which is suitable for labeling intracellular pH-dependent organelles. BP displayed strong red emission at a relatively high pH in living HeLa cells and U87 cells. More importantly, this probe exhibited good colocalization with both mitochondria and lysosomes in these two cell lines, attributing to pH-induced structure tautomerism resulting in an oxazolidine ring open and close that triggered effective targeting of these two organelles. As organelle interactions are critical for cellular processes, this strategy of targeting dual organelles through the structure tautomerism is conducive to further developing more effective and advanced probes for real-time imaging of the interaction between mitochondria and lysosomes.

Brain pH Measurement Using AACID CEST MRI Incorporating the 2 ppm Amine Resonance

Many pathological conditions lead to altered intracellular pH (pH_i) disrupting normal cellular functions. The chemical exchange saturation transfer (CEST) method, known as Amine and Amide Concentration Independent Detection (AACID), can produce image contrast that is predominantly dependent on tissue intracellular pH_i. The AACID value is linearly related to the ratio of the 3.5 ppm amide CEST effect and the 2.75 ppm amine CEST effect in the physiological range. However, the amine CEST effect at 2 ppm is often more clearly defined in vivo, and may provide greater sensitivity to pH changes. The purpose of the current study was to compare AACID measurement precision utilizing the 2.0 and 2.75 ppm amine CEST effects. We hypothesized that the 2.0 ppm amine CEST resonance would produce measurements with greater sensitivity to pH changes. In the current study, we compare the range of the AACID values obtained in 24 mice with brain tumors and in normal tissue using the 2 ppm and 2.75 ppm amine resonances. All CEST data were acquired on a 9.4T MRI scanner. The AACID measurement range increased by 39% when using the 2 ppm amine resonance compared to the 2.75 ppm resonance, with decreased measurement variability across the brain. These data indicate that in vivo pH measurements made using AACID CEST can be enhanced by incorporating the 2 ppm amine resonance. This approach should be considered for pH measurements made over short intervals when no changes are expected in the concentration of metabolites that contribute to the 2 ppm amine resonance.

Imaging the Rewired Metabolism in Lung Cancer in Relation to Immune Therapy

Metabolic reprogramming is recognized as one of the hallmarks of cancer. Alterations in the micro-environmental metabolic characteristics are recognized as important tools for cancer cells to interact with the resident and infiltrating T-cells within this tumor microenvironment. Cancer-induced metabolic changes in the micro-environment also affect treatment outcomes. In particular, immune therapy efficacy might be blunted because of somatic mutation-driven metabolic determinants of lung cancer such as acidity and oxygenation status. Based on these observations, new onco-immunological treatment strategies increasingly include drugs that interfere with metabolic pathways that consequently affect the composition of the lung cancer tumor microenvironment (TME). Positron emission tomography (PET) imaging has developed a wide array of tracers targeting metabolic pathways, originally intended to improve cancer detection and staging. Paralleling the developments in understanding metabolic reprogramming in cancer cells, as well as its effects on stromal, immune, and endothelial cells, a wave of studies with additional imaging tracers has been published. These tracers are yet underexploited in the perspective of immune therapy. In this review, we provide an overview of currently available PET tracers for clinical studies and discuss their potential roles in the development of effective immune therapeutic strategies, with a focus on lung cancer. We report on ongoing efforts that include PET/CT to understand the outcomes of interactions between cancer cells and T-cells in the lung cancer microenvironment, and we identify areas of research which are yet unchartered. Thereby, we aim to provide a starting point for molecular imaging driven studies to understand and exploit metabolic features of lung cancer to optimize immune therapy.

A mathematical model for imaging and killing cancer cells by using concepts of the Warburg effect in designing a Graphene system

According to the Warburg effect, there are some significant differences between metabolisms, products and process of respirations of cancer cells and normal cells. For example, normal cells absorb oxygen and glucose and give water molecules, carbon dioxide, ATP molecules and some number of spinors; while cancer cells take glucose and give lactate, less number of ATP molecules and different number of spinors. Using this property, we can design a system from two graphene sheets that are connected by pairing the fourth free electrons of carbons. Then, we can break some pairs and produce some holes. The number of these holes should be equal to the number of radiated spinors by normal cells. Near a normal cell, all holes are filled and the graphene system doesn't emit any electrical current or wave. However, near a cancer cell, some extra holes or spinors remain that their motions produce some electrical currents. These currents force on cancer cell membranes and destroy them and consequently, cause the cell death. Also, these currents emit some electromagnetic waves which detectors could take them out of the human's body and consequently, they could play the main role in imaging.

Of mitochondrion and COVID-19

COVID-19, a pandemic disease caused by a viral infection, is associated with a high mortality rate. Most of the signs and symptoms, e.g. cytokine storm, electrolytes imbalances, thromboembolism, etc., are related to mitochondrial dysfunction. Therefore, targeting mitochondrion will represent a more rational treatment of COVID-19. The current work outlines how COVID-19's signs and symptoms are related to the mitochondrion. Proper understanding of the underlying causes might enhance the opportunity to treat COVID-19.

Tumor microenvironment and nanotherapeutics: intruding the tumor fort

Over recent years, advancements in nanomedicine have allowed new approaches to diagnose and treat tumors. Nano drug delivery systems exploit the enhanced permeability and retention (EPR) effect and enter the tumor tissue's interstitial space. However, tumor barriers play a crucial role, and cause inefficient EPR or the homing effect. Mounting evidence supports the hypothesis that the components of the tumor microenvironment, such as the extracellular matrix, and cellular and physiological components collectively or cooperatively hinder entry and distribution of drugs, and therefore, limit the theragnostic applications of cancer nanomedicine. This abnormal tumor microenvironment plays a pivotal role in cancer nanomedicine and was recently recognized as a promising target for improving nano-drug delivery and their therapeutic outcomes. Strategies like passive or active targeting, stimuli-triggered nanocarriers, and the modulation of immune components have shown promising results in achieving anticancer efficacy. The present review focuses on the tumor microenvironment and nanoparticle-based strategies (polymeric, inorganic and organic nanoparticles) for intruding the tumor barrier and improving therapeutic effects.

Uncovering the interplay between pH receptors and immune cells: Potential drug targets (Review)

Extracellular acidosis is associated with various immunopathological states. The microenvironment of numerous solid tumours and inflammatory responses during acute or chronic infection are all related to a pH range of 5.5‑7.0. The relationship between inflammation and immune escape, cancer metabolism, and immunologic suppression drives researchers to focus on the effects of low pH on diverse components of disease immune monitoring. The potential effect of low extracellular pH on the immune function reveals the importance of pH in inflammatory and immunoreactive processes. In this review, the mechanism of how pH receptors, including monocarboxylate transporters (MCTs), Na⁺/H⁺ exchanger 1, carbonic anhydrases (CAs), vacuolar‑ATPase, and proton‑sensing G‑protein coupled receptors (GPCRs), modulate the immune system in disease, especially in cancer, were studied. Their role in immunocyte growth and signal transduction as part of the immune response, as well as cytokine production, have been documented in great detail. Currently, immunotherapy strategies have positive therapeutic effects for patients. However, the acidic microenvironment may block the effect of immunotherapy through compensatory feedback mechanisms, leading to drug resistance. Therefore, we highlight promising therapeutic developments regarding pH manipulation and provide a framework for future research.

Metabolic Shifts as the Hallmark of Most Common Diseases: The Quest for the Underlying Unity

A hyper-specialization characterizes modern medicine with the consequence of classifying the various diseases of the body into unrelated categories. Such a broad diversification of medicine goes in the opposite direction of physics, which eagerly looks for unification. We argue that unification should also apply to medicine. In accordance with the second principle of thermodynamics, the cell must release its entropy either in the form of heat (catabolism) or biomass (anabolism). There is a decreased flow of entropy outside the body due to an age-related reduction in mitochondrial entropy yield resulting in increased release of entropy in the form of biomass. This shift toward anabolism has been known in oncology as Warburg-effect. The shift toward anabolism has been reported in most diseases. This quest for a single framework is reinforced by the fact that inflammation (also called the immune response) is involved in nearly every disease. This strongly suggests that despite their apparent disparity, there is an underlying unity in the diseases. This also offers guidelines for the repurposing of old drugs.

Overexpressed CA12 has prognostic value in pancreatic cancer and promotes tumor cell apoptosis via NF-κB signaling

INTRODUCTION

Pancreatic adenocarcinoma (PAAD) is among the deadliest forms of cancer globally. Carbonic anhydrase 12 (CA12) is known to play central roles in regulating many cancers, but its function in the context of PAAD is rarely discussed. This study was, therefore, designed to assess the expression of CA12 in PAAD and to explore its underlying mechanistic role in this cancer type.

METHODS

Immunohistochemical staining was used to measure CA12 expression in PAAD samples. The functionality of pancreatic cancer cells expressing varying levels of CA12 was assessed through wound healing, Transwell, and CCK-8 assays. In addition, flow cytometry was used to measure apoptosis and cell cycle progression in these same cells, while Western blotting was used to analyze the expression of proteins associated with the NF-κB signaling pathway.

RESULTS

PAAD tissue samples exhibited significant CA12 downregulation (P < 0.001), and lower CA12 expression was, in turn, associated with poorer overall survival (P < 0.001). CA12 overexpression significantly impaired the proliferation of PAAD cell lines, instead inducing their apoptotic death and G0/G1 phase cell cycle arrest (P < 0.05). We additionally found that CA12 may exert its tumor suppressive roles via modulating the NF-κB signaling pathway.

CONCLUSION

These results indicate that CA12 functions as a tumor suppressor in PAAD and may thus be a novel therapeutic target that can be used to guide PAAD patient treatment.

Towards an Integral Therapeutic Protocol for Breast Cancer Based upon the New H+-Centered Anticancer Paradigm of the Late Post-Warburg Era

A brand new approach to the understanding of breast cancer (BC) is urgently needed. In this contribution, the etiology, pathogenesis, and treatment of this disease is approached from the new pH-centric anticancer paradigm. Only this unitarian perspective, based upon the hydrogen ion (H+) dynamics of cancer, allows for the understanding and integration of the many dualisms, confusions, and paradoxes of the disease. The new H+-related, wide-ranging model can embrace, from a unique perspective, the many aspects of the disease and, at the same time, therapeutically interfere with most, if not all, of the hallmarks of cancer known to date. The pH-related armamentarium available for the treatment of BC reviewed here may be beneficial for all types and stages of the disease. In this vein, we have attempted a megasynthesis of traditional and new knowledge in the different areas of breast cancer research and treatment based upon the wide-ranging approach afforded by the hydrogen ion dynamics of cancer. The concerted utilization of the pH-related drugs that are available nowadays for the treatment of breast cancer is advanced.

The Anti-Tumor Effects of Oenothera odorata Extract Are Mediated by Inhibition of Glycolysis and Cellular Respiration in Cancer Cells

Cancer is caused by uncontrolled cell division and is a leading cause of mortality worldwide. Oenothera odorata (O. odorata) extract is used in herbal medicine to inhibit inflammation, but its potential anti-tumor properties have not been fully evaluated. Here, we demonstrated that O. odorata extract inhibits the proliferation of lung adenocarcinoma and melanoma cell lines In Vitro, and also inhibits the growth of melanoma cells In Vivo. After partitioning the extract with n-hexane, chloroform, ethyl acetate, and n-butanol, it was found that the butanol-soluble (OOB) and water-soluble (OOW) fractions of O. odorata extract are effective at inhibiting tumor cell growth In Vivo although OOW is more effective than OOB. Interestingly, these fractions did not inhibit the growth of non-cancerous cells. The anti-proliferative effects of the OOW fraction were found to be mediated by inhibition of glycolysis and cellular respiration. UPLC of both fractions showed two major common peaks, which were predicted to be hydrolyzable tannin-related compounds. Taken together, these data suggest that O. odorata extract has anti-tumor properties, and the molecular mechanism involves metabolic alterations and inhibition of cell proliferation. O. odorata extract therefore holds promise as a novel natural product for the treatment of cancer.

Antitumor effects of curcumin on the proliferation, migration and apoptosis of human colorectal carcinoma HCT‑116 cells

Curcumin is the main component of the Chinese herbal plant turmeric, which has been demonstrated to possess antitumor and other pharmacological properties. The aim of the present study was to investigate the effects of curcumin on the viability, migration and apoptosis of human colorectal carcinoma HCT-116 cells, and to explore the underlying molecular mechanisms. In addition, it was investigated whether the antitumor effect of curcumin on HCT-116 cells could match that of the chemotherapeutic drug 5-fluorouracil (5-FU). HCT-116 cells were treated with curcumin (10, 20 and 30 µM) and 5-FU (500 µM), and cell viability and proliferation were detected by Cell Counting Kit-8 and colony formation assays, respectively. The migration and invasion of treated cells were determined using Transwell and carboxyfluorescein succinimidyl amino ester fluorescent labeling assays. Cell cycle distribution and apoptosis rates were detected by flow cytometry. Furthermore, cell morphology changes associated with apoptosis were observed by fluorescence microscopy with acridine orange/ethidium bromide dual staining. To investigate the possible underlying molecular mechanisms, the gene and protein levels of Fas, Fas-associated via death domain (FADD), caspase-8, caspase-3, matrix metalloproteinase (MMP)-9, nuclear factor (NF)-κB, E-cadherin and claudin-3 were detected using quantitative PCR analysis, zymography and western blotting. The results revealed that curcumin markedly inhibited the viability and proliferation of HCT-116 cells in a dose- and time-dependent manner. The migration, aggregation and invasion of HCT-116 cells into the lungs of mice were decreased by curcumin treatment in a dose-dependent manner. S-phase arrest and gradually increased apoptotic rates of HCT-116 cells were observed with increasing curcumin concentrations. Additionally, the mRNA and protein levels of apoptosis-associated proteins (Fas, FADD, caspase-8 and caspase-3) and E-cadherin in HCT-116 cells were upregulated following treatment with curcumin in a dose-dependent manner. By contrast, the expression of migration-associated proteins, including MMP-9, NF-κB and claudin-3, was downregulated with increasing curcumin concentrations. These data suggested that the inhibitory effect of curcumin on HCT-116 cells may match that of 5-FU. Therefore, curcumin induced cell apoptosis and inhibited tumor cell metastasis by regulating the NF-κB signaling pathway, and its therapeutic effect may be comparable to that of 5-FU.

Pathophysiology of hepatic Na+/H+ exchange (Review)

Na+/H+ exchangers (NHEs) are a family of membrane proteins that contribute to exchanging one intracellular proton for one extracellular sodium. The family of NHEs consists of nine known members, NHE1-9. Each isoform represents a different gene product that has unique tissue expression, membrane localization, physiological effects, pathological regulation and sensitivity to drug inhibitors. NHE1 was the first to be discovered and is often referred to as the 'housekeeping' isoform of the NHE family. NHEs are not only involved in a variety of physiological processes, including the control of transepithelial Na+ absorption, intracellular pH, cell volume, cell proliferation, migration and apoptosis, but also modulate complex pathological events. Currently, the vast majority of review articles have focused on the role of members of the NHE family in inflammatory bowel disease, intestinal infectious diarrhea and digestive system tumorigenesis, but only a few reviews have discussed the role of NHEs in liver disease. Therefore, the present review described the basic biology of NHEs and highlighted their physiological and pathological effects in the liver.

Differential Metabolic Alterations and Biomarkers Between Gastric Cancer and Colorectal Cancer: A Systematic Review and Meta-Analysis

Purpose

Numerous metabolomics studies have been conducted to detect the metabolic mechanisms and biomarkers related to gastric cancer and colorectal cancer. Because of the common metabolic features between gastric cancer and colorectal cancer, a differential diagnosis is difficult. Here, we performed a systematic review and meta-analysis to identify differential metabolic biomarkers between these two types of cancers.

Materials and Methods

PubMed, Embase, and ScienceDirect were searched to identify all metabolomics studies of gastric cancer and colorectal cancer published up to September 2018. Differential metabolites or altered pathways were extracted. The intersections and differences for these metabolites and pathways between gastric cancer and colorectal cancer were compared. Candidate biomarker sets for diagnosis were proposed from biofluid or feces by comparing them with tumor tissues.

Results

Totally, 24 and 65 studies were included in gastric cancer and colorectal cancer, and 223 and 472 differential metabolites were extracted, respectively. Eight pathways were reproducibly enriched in blood, tissue and urine in gastric cancer, while, 11 pathways were reproducibly enriched in blood, urine, feces and tissue in colorectal cancer. Candidate metabolic biomarker sets in blood, urine, or feces for these two cancers were proposed. We found 27 pathways (categorized into eight classifications) common to both cancers, five pathways involving 35 metabolites enriched only in gastric cancer, and eight pathways involving 54 metabolites enriched only in colorectal cancer.

Conclusion

The altered metabolic pathways showed signatures of abnormal metabolism in gastric cancer and colorectal cancer; the potential metabolic biomarkers proposed in this study have important implications for the prospective validation of gastric cancer and colorectal cancer.

Imaging the Cancer Immune Environment and Its Response to Pharmacologic Intervention, Part 1: The Role of 18F-FDG PET/CT

Immunotherapy agents are now entering the clinic in a wide array of malignancies and have provided a valuable addition to the therapeutic armamentarium. These agents enhance the global immune response by modulating the tumor microenvironment but can lead to unconventional patterns of response, challenging the conceptual framework that imaging is a robust surrogate for therapeutic efficacy. There is also increasing evidence that an effective antitumor response requires a systemic immune response in primary and secondary lymphoid tissues. However, an enhanced systemic immune response can lead to disruption of immunologic hemostasis in healthy tissues, causing adverse events. Better understanding of the complex interplay between tumoral and systemic immune response has been provided through tissue and liquid biopsy. However, the applicability of these methods is constrained by the biologic, spatial, and temporal heterogeneity of the processes involved. There is a growing interest in molecular imaging of cell-specific lineage markers of the immune system using biomolecules. However, the ongoing role of the more widely available ¹⁸F-FDG PET/CT for response assessment is being recognized through ongoing refinement of interpretative guidelines and emerging evidence. These noninvasive methods provide insights into the biologic basis of the global immune response to maximize potential therapeutic benefit. In this review, we aim to provide an overview of the current status of ¹⁸F-FDG PET/CT in the monitoring of tumoral and systemic immune response. In a companion review, the role of other imaging probes that might complement ¹⁸F-FDG PET/CT will be discussed.

The Interplay of Dysregulated pH and Electrolyte Imbalance in Cancer

Cancer cells and tissues have an aberrant regulation of hydrogen ion dynamics driven by a combination of poor vascular perfusion, regional hypoxia, and increased the flux of carbons through fermentative glycolysis. This leads to extracellular acidosis and intracellular alkalinization. Dysregulated pH dynamics influence cancer cell biology, from cell transformation and tumorigenesis to proliferation, local growth, invasion, and metastasis. Moreover, this dysregulated intracellular pH (pHi) drives a metabolic shift to increased aerobic glycolysis and reduced mitochondrial oxidative phosphorylation, referred to as the Warburg effect, or Warburg metabolism, which is a selective feature of cancer. This metabolic reprogramming confers a thermodynamic advantage on cancer cells and tissues by protecting them against oxidative stress, enhancing their resistance to hypoxia, and allowing a rapid conversion of nutrients into biomass to enable cell proliferation. Indeed, most cancers have increased glucose uptake and lactic acid production. Furthermore, cancer cells have very dysregulated electrolyte balances, and in the interaction of the pH dynamics with electrolyte, dynamics is less well known. In this review, we highlight the interconnected roles of dysregulated pH dynamics and electrolytes imbalance in cancer initiation, progression, adaptation, and in determining the programming and reprogramming of tumor cell metabolism.

A New and Integral Approach to the Etiopathogenesis and Treatment of Breast Cancer Based upon Its Hydrogen Ion Dynamics

Despite all efforts, the treatment of breast cancer (BC) cannot be considered to be a success story. The advances in surgery, chemotherapy and radiotherapy have not been sufficient at all. Indeed, the accumulated experience clearly indicates that new perspectives and non-main stream approaches are needed to better characterize the etiopathogenesis and treatment of this disease. This contribution deals with how the new pH-centric anticancer paradigm plays a fundamental role in reaching a more integral understanding of the etiology, pathogenesis, and treatment of this multifactorial disease. For the first time, the armamentarium available for the treatment of the different types and phases of BC is approached here from a Unitarian perspective-based upon the hydrogen ion dynamics of cancer. The wide-ranged pH-related molecular, biochemical and metabolic model is able to embrace most of the fields and subfields of breast cancer etiopathogenesis and treatment. This single and integrated approach allows advancing towards a unidirectional, concerted and synergistic program of treatment. Further efforts in this line are likely to first improve the therapeutics of each subtype of this tumor and every individual patient in every phase of the disease.

Inhibition of PFKFB3 suppresses osteoclastogenesis and prevents ovariectomy-induced bone loss

Osteoclasts are multinucleated cells derived from the monocyte/macrophage cell lineage under the regulation of receptor activator of nuclear factor‐κB ligand (RANKL). In previous studies, stimulation by RANKL during osteoclastogenesis was shown to induce a metabolic switch to enhanced glycolytic metabolism. Thus, we hypothesized that blockage of glycolysis might serve as a novel strategy to treat osteoclast‐related diseases. In the present study, 6‐phosphofructo‐2‐kinase/fructose‐2,6‐bisphosphatase 3 (PFKFB3), an essential regulator of glycolysis, was up‐regulated during osteoclast differentiation. Genetic and pharmacological inhibition of PFKFB3 in bone marrow‐derived macrophages suppressed the differentiation and function of osteoclasts. Moreover, intraperitoneal administration of the PFKFB3 inhibitor PFK15 prevented ovariectomy‐induced bone loss. In addition, glycolytic activity characterized by lactate accumulation and glucose consumption in growth medium was reduced by PFKFB3 inhibition. Further investigation indicated that the administration of L‐lactate partially reversed the repression of osteoclastogenesis caused by PFKFB3 inhibition and abrogated the inhibitory effect of PFK15 on the activation of NF‐κB and MAPK pathways. In conclusion, the results of this study suggest that blockage of glycolysis by targeting PFKFB3 represents a potential therapeutic strategy for osteoclast‐related disorders.

Behind the Wheel of Epithelial Plasticity in KRAS-Driven Cancers

Cellular plasticity, a feature associated with epithelial-to-mesenchymal transition (EMT), contributes to tumor cell survival, migration, invasion, and therapy resistance. Phenotypic plasticity of the epithelium is a critical feature in multiple phases of human cancer in an oncogene- and tissue-specific context. Many factors can drive epithelial plasticity, including activating mutations in KRAS, which are found in an estimated 30% of all cancers. In this review, we will introduce cellular plasticity and its effect on cancer progression and therapy resistance and then summarize the drivers of EMT with an emphasis on KRAS effector signaling. Lastly, we will discuss the contribution of cellular plasticity to metastasis and its potential clinical implications. Understanding oncogenic KRAS cellular reprogramming has the potential to reveal novel strategies to control metastasis in KRAS-driven cancers.

Drug Repurposing as an Antitumor Agent: Disulfiram-Mediated Carbonic Anhydrase 12 and Anion Exchanger 2 Modulation to Inhibit Cancer Cell Migration

Disulfiram has been used in the treatment of alcoholism and exhibits an anti-tumor effect. However, the intracellular mechanism of anti-tumor activity of Disulfiram remains unclear. In this study, we focused on the modulatory role of Disulfiram via oncogenic factor carbonic anhydrase CA12 and its associated transporter anion exchanger AE2 in lung cancer cell line A549. The surface expression of CA12 and AE2 were decreased by Disulfiram treatment with a time-dependent manner. Disulfiram treatment did not alter the expression of Na⁺-bicarbonate cotransporters, nor did it affect autophagy regulation. The chloride bicarbonate exchanger activity of A549 cells was reduced by Disulfiram treatment in a time-dependent manner without change in the resting pH level. The expression and activity of AE2 and the expression of CA12 were also reduced by Disulfiram treatment in the breast cancer cell line. An invasion assay and cell migration assay revealed that Disulfiram attenuated the invasion and migration of A549 cells. In conclusion, the attenuation of AE2 and its supportive enzyme CA12, and the inhibitory effect on cell migration by Disulfiram treatment in cancer cells provided the molecular evidence supporting the potential of Disulfiram as an anticancer agent.

Trends and Challenges in Tumor Anti-Angiogenic Therapies

Excessive abnormal angiogenesis plays a pivotal role in tumor progression and is a hallmark of solid tumors. This process is driven by an imbalance between pro- and anti-angiogenic factors dominated by the tissue hypoxia-triggered overproduction of vascular endothelial growth factor (VEGF). VEGF-mediated signaling has quickly become one of the most promising anti-angiogenic therapeutic targets in oncology. Nevertheless, the clinical efficacy of this approach is severely limited in certain tumor types or shows only transient efficacy in patients. Acquired or intrinsic therapy resistance associated with anti-VEGF monotherapeutic approaches indicates the necessity of a paradigm change when targeting neoangiogenesis in solid tumors. In this context, the elaboration of the conceptual framework of “vessel normalization” might be a promising approach to increase the efficacy of anti-angiogenic therapies and the survival rates of patients. Indeed, the promotion of vessel maturation instead of regressing tumors by vaso-obliteration could result in reduced tumor hypoxia and improved drug delivery. The implementation of such anti-angiogenic strategies, however, faces several pitfalls due to the potential involvement of multiple pro-angiogenic factors and modulatory effects of the innate and adaptive immune system. Thus, effective treatments bypassing relapses associated with anti-VEGF monotherapies or breaking the intrinsic therapy resistance of solid tumors might use combination therapies or agents with a multimodal mode of action. This review enumerates some of the current approaches and possible future directions of treating solid tumors by targeting neovascularization.

The Role of Sodium Hydrogen Exchanger 1 in Dysregulation of Proton Dynamics and Reprogramming of Cancer Metabolism as a Sequela

Cancer cells have an unusual regulation of hydrogen ion dynamics that are driven by poor vascularity perfusion, regional hypoxia, and increased glycolysis. All these forces synergize/orchestrate together to create extracellular acidity and intracellular alkalinity. Precisely, they lead to extracellular pH (pH_e) values as low as 6.2 and intracellular pH values as high as 8. This unique pH gradient (∆pH_i to ∆pH_e) across the cell membrane increases as the tumor progresses, and is markedly displaced from the electrochemical equilibrium of protons. These unusual pH dynamics influence cancer cell biology, including proliferation, metastasis, and metabolic adaptation. Warburg metabolism with increased glycolysis, even in the presence of Oxygen with the subsequent reduction in Krebs’ cycle, is a common feature of most cancers. This metabolic reprogramming confers evolutionary advantages to cancer cells by enhancing their resistance to hypoxia, to chemotherapy or radiotherapy, allowing rapid production of biological building blocks that support cellular proliferation, and shielding against damaging mitochondrial free radicals. In this article, we highlight the interconnected roles of dysregulated pH dynamics in cancer initiation, progression, adaptation, and in determining the programming and re-programming of tumor cell metabolism.

LncRNA SNHG1 contributes to sorafenib resistance by activating the Akt pathway and is positively regulated by miR-21 in hepatocellular carcinoma cells

Background

Acquired resistance to sorafenib greatly limits its therapeutic efficiency in the treatment of hepatocellular carcinoma (HCC). Increasing evidence indicates that long noncoding RNAs (lncRNAs) play important roles in the resistance to anti-cancer drugs. The present study aims to explore the involvement of lncRNA SNHG1 (small nucleolar RNA host gene 1) in sorafenib resistance and how SNHG1 is associated with overexpressed microRNA-21 (miR-21) and the activated Akt pathway, which have been demonstrated to mediate this resistance in HCC cells.

Methods

Sorafenib-resistant HCC (SR-HCC) cells were generated and their sorafenib-resistant properties were confirmed by cell viability and apoptosis assays. Potential lncRNAs were screened by using multiple bioinformatics analyses and databases. The expression of genes and proteins was detected by qRT-PCR, Western blot and in situ hybridization. Gene silencing was achieved by specific siRNA or lncRNA Smart Silencer. The effects of anti-SNHG1 were evaluated in vitro and in experimental animals by using quantitative measures of cell proliferation, apoptosis and autophagy. The binding sites of miR-21 and SNHG1 were predicted by using the RNAhybrid algorithm and their interaction was verified by luciferase assays.

Results

The Akt pathway was highly activated by overexpressed miR-21 in SR-HCC cells compared with parental HCC cells. Among ten screened candidates, SNHG1 showed the largest folds of alteration between SR-HCC and parental cells and between vehicle- and sorafenib-treated cells. Overexpressed SNHG1 contributes to sorafenib resistance by activating the Akt pathway via regulating SLC3A2. Depletion of SNHG1 enhanced the efficacy of sorafenib to induce apoptosis and autophagy of SR-HCC cells by inhibiting the activation of Akt pathway. Sorafenib induced translocation of miR-21 to the nucleus, where it promoted the expression of SNHG1, resulting in upregulation of SLC3A2, leading to the activation of Akt pathway. In contrast, SNHG1 was shown to have little effect on the expression of miR-21, which downregulated the expression of PTEN, leading to the activation of the Akt pathway independently of SNHG1.

Conclusions

The present study has demonstrated that lncRNA SNHG1 contributes to sorafenib resistance by activating the Akt pathway and its nuclear expression is promoted by miR-21, whose nuclear translocation is induced by sorafenib. These results indicate that SNHG1 may represent a potentially valuable target for overcoming sorafenib resistance for HCC.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1177-0) contains supplementary material, which is available to authorized users.

Acidic Stress Triggers Sodium-Coupled Bicarbonate Transport and Promotes Survival in A375 Human Melanoma Cells

Melanoma cells preserve intracellular pH (pH_i) within a viable range despite an acidic ambient pH that typically falls below pH 7.0. The molecular mechanisms underlying this form of acidic preservation in melanoma remain poorly understood. Previous studies had demonstrated that proton transporters including the monocarboxylate transporter (MCT), the sodium hydrogen exchanger (NHE), and V-Type ATPase mediate acid extrusion to counter intracellular acidification in melanoma cells. In this report, the expression and function of the Sodium-Coupled Bicarbonate Transporter (NCBT) family of base loaders were further characterized in melanoma cell lines. NCBT family members were found to be expressed in three different melanoma cell lines – A375, MeWo, and HS695T – and included the electrogenic sodium-bicarbonate cotransporter isoforms 1 and 2 (NBCe1 and NBCe2), the electroneutral sodium-bicarbonate cotransporter (NBCn1), and the sodium-dependent chloride-bicarbonate exchanger (NDCBE). These transporters facilitated 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS)-dependent pH_i recovery in melanoma cells, in response to intracellular acidification induced by ammonium chloride prepulse. Furthermore, the expression of NCBTs were upregulated via chronic exposure to extracellular acidification. Given the current research interest in the NCBTs as a molecular driver of tumourigenesis, characterising NCBT in melanoma provides impetus for developing novel therapeutic targets for melanoma treatment.

Repurposing old carbon monoxide-releasing molecules towards the anti-angiogenic therapy of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is defined by the lack of expression of the oestrogen and progesterone receptors and HER-2. Recently, carbon monoxide (CO) was found to behave as an important endogenous signalling molecule and to suppress VEGF receptor-2 (VEGFR-2) and protein kinase B phosphorylation. Given that anti-angiogenic drugs exist as one of the few available targeted therapies against TNBC, the aim of this project was to study the effects of CO-releasing molecules (CORMs) on TNBC cell lines and the associated endothelial cells and characterise their anti-angiogenic properties that can be used for the reduction of cancer-driven angiogenesis. Four commercially available CORMs were screened for their cytotoxicity, their effects on cell metabolism, migration, VEGF expression, tube formation and VEGFR-2 activation. The most important result was the reduction in VEGF levels expressed by CORM-treated TNBC cells, along with the inhibition of phosphorylation of VEGFR2 and downstream proteins. The migration and tube formation ability of endothelial cells was also decreased by CORMs, justifying a potential re-purposing of old CORMs towards the anti-angiogenic therapy of TNBC. The additional favourable low cytotoxicity, reduction in the glycolysis levels and downregulation of haem oxygenase-1 in TNBC cells enhance the potential of CORMs against TNBC. In this study, CORM-2 remained the most effective CORM and we propose that CORM-2 may be pursued further as an additional agent in combination with existing anti-angiogenic therapies for a more successful targeting of malignant angiogenesis in TNBC.

Deciphering the metabolic role of AMPK in cancer multi-drug resistance

Multi-drug resistance (MDR) is a curious bottleneck in cancer research and chemotherapy, whereby some cells rapidly adapt to the tumor microenvironment via a myriad of heterogeneous metabolic activities. Despite being a major impediment to treatment, there is a silver lining: control over metabolic regulation could be an effective approach to overcome or correct resistance pathways. In this critical review, we comprehensively and carefully curated and analyzed large networks of previously identified proteins associated with metabolic adaptation in MDR. We employed data and text mining to study and categorize more than 600 studies in PubMed, with particular focus on AMPK, a central and fundamental modulator in the energy metabolism network that has been specifically implicated in cancer MDR pathways. We have identified one protein set of metabolic adaptations with 137 members closely related to cancer MDR processes, and a second protein set with 165 members derived from AMPK-based networks, with 28 proteins found at the intersection between the two sets. Furthermore, according to genomics analysis of the cancer genome atlas (TCGA) provisional data, the highest alteration frequency (80.0%) of the genes encoding the intersected proteins (28 proteins), ranked three cancer types with quite remarkable significance across 166 studies. The hierarchical relationships of the entire identified gene and protein networks indicate broad correlations in AMPK-mediated metabolic regulation pathways, which we use decipher and depict the metabolic roles of AMPK and demonstrate the potential of metabolic control for therapeutic intervention in MDR.

A positive feedback loop between miR-181b and STAT3 that affects Warburg effect in colon cancer via regulating PIAS3 expression

This study aimed to investigate the relationship between the expression of microRNA (miR)‐181b, protein inhibitor of activated STAT3 (PIAS3) and STAT3, and to examine the function of the miR‐181b/PIAS3/STAT3 axis on the Warburg effect and xenograft tumour growth of colon cancer. Moreover, a positive feedback loop between miR‐181b and STAT3 that regulated the Warburg effect in colon cancer was explored. A luciferase reporter assay was used to identify whether PIAS3 was a direct target of miR‐181b. The gain‐of‐function and loss‐of‐function experiments were performed on HCT 116 cells to investigate the effect of miR‐181b/PIAS3/STAT3 on the Warburg effect and xenograft tumour growth of colon cancer, as determined by commercial kits and xenograft experiments. The relationship between the expression of miR‐181b, PIAS3 and STAT3 in HCT 116 and HT‐29 cells was determined using RT‐qPCR and Western blot. We found miR‐181b was a direct regulator of PIAS3. miR‐181b promoted the Warburg effect and the growth of colon cancer xenografts; however, these effects could be reversed by PIAS3. miR‐181b expression interacted with STAT3 phosphorylation in a positive feedback loop in colon cancer cells via regulating PIAS3 expression. In conclusion, this study for the first time demonstrated that miR‐181b contributed to the Warburg effect and xenograft tumour growth of colon cancer by targeting PIAS3. Moreover, a positive feedback loop between miR‐181b and STAT3 that regulated the Warburg effect in colon cancer was also demonstrated. This study suggested miR‐181b/PIAS3/STAT3 axis as a novel target for colon cancer treatment.

Downregulation of MCT4 for lactate exchange promotes the cytotoxicity of NK cells in breast carcinoma

Monocarboxylate transporter‐4 (MCT4), a monocarboxylic acid transporter, demonstrates significantly increased expression in the majority of malignancies. We performed an experiment using BALB/C mice, and our results showed that ShMCT4 transfection or the pharmaceutic inhibition of MCT4 with 7acc1 strengthens the activity of NK cells. The results of a calcein assay revealed that the cytotoxicity of NK cells was strengthened via inhibition of MCT4. In addition, ELISA testing showed that the content of perforin and CD107a was increased, and PCR amplification and immunoblotting revealed that the expression of NKG2D and H60 was upregulated after the inhibition of MCT4. Further, we observed an elevated pH value, decreased extracellular lactate flow, and attenuated tumor growth. Therefore, we concluded that the inhibition of MCT4 enhanced the cytotoxicity of NK cells by blocking lactate flux and reversing the acidified tumor microenvironment. In addition to these findings, we also discovered that MCT4 depletion may have a pronounced impact on autophagy, which was surmised by observing that the inhibition of autophagy (3MA) pulled the enhanced cytotoxicity of NK cells downwards. Together, these data suggest that the key effect of MCT4 depletion on NK cells probably utilizes inductive autophagy as a compensatory metabolic mechanism to minimize the acidic extracellular microenvironment associated with lactate export in tumors.

Glycosylation Changes in Brain Cancer

Protein glycosylation is a posttranslational modification that affects more than half of all known proteins. Glycans covalently bound to biomolecules modulate their functions by both direct interactions, such as the recognition of glycan structures by binding partners, and indirect mechanisms that contribute to the control of protein conformation, stability, and turnover. The focus of this Review is the discussion of aberrant glycosylation related to brain cancer. Altered sialylation and fucosylation of N- and O-glycans play a role in the development and progression of brain cancer. Additionally, aberrant O-glycan expression has been implicated in brain cancer. This Review also addresses the clinical potential and applications of aberrant glycosylation for the detection and treatment of brain cancer. The viable roles glycans may play in the development of brain cancer therapeutics are addressed as well as cancer-glycoproteomics and personalized medicine. Glycoprotein alterations are considered as a hallmark of cancer while high expression in body fluids represents an opportunity for cancer assessment.

Cancer metabolism: New insights into classic characteristics

Initial studies of cancer metabolism in the early 1920s found that cancer cells were phenotypically characterized by aerobic glycolysis, in that these cells favor glucose uptake and lactate production, even in the presence of oxygen. This property, called the Warburg effect, is considered a hallmark of cancer. The mechanism by which these cells acquire aerobic glycolysis has been uncovered. Acidic extracellular fluid, secreted by cancer cells, induces a malignant phenotype, including invasion and metastasis. Cancer cells survival depends on a critical balance of redox status, which is regulated by amino acid metabolism. Glutamine is extremely important for oxidative phosphorylation and redox regulation. Cells highly dependent on glutamine and that cannot survive with glutamine are called glutamine-addicted cells. Metabolic reprogramming has been observed in cancer stem cells, which have the property of self-renewal and are resistant to chemotherapy and radiotherapy. These findings suggest that studies of cancer metabolism can reveal methods of preventing cancer recurrence and metastasis.

Cariporide Enhances the DNA Damage and Apoptosis in Acid-tolerable Malignant Mesothelioma H-2452 Cells

The Na+/H+ exchanger is responsible for maintaining the acidic tumor microenvironment through its promotion of the reabsorption of extracellular Na+ and the extrusion of intracellular H+. The resultant increase in the extracellular acidity contributes to the chemoresistance of malignant tumors. In this study, the chemosensitizing effects of cariporide, a potent Na+/H+-exchange inhibitor, were evaluated in human malignant mesothelioma H-2452 cells preadapted with lactic acid. A higher basal level of phosphorylated (p)-AKT protein was found in the acid-tolerable H-2452AcT cells compared with their parental acid-sensitive H-2452 cells. When introduced in H-2452AcT cells with a concentration that shows only a slight toxicity in H-2452 cells, cariporide exhibited growth-suppressive and apoptosis-promoting activities, as demonstrated by an increase in the cells with pyknotic and fragmented nuclei, annexin V-PE(+) staining, a sub-G0/G1 peak, and a G2/M phase-transition delay in the cell cycle. Preceding these changes, a cariporide-induced p-AKT down-regulation, a p53 up-regulation, an ROS accumulation, and the depolarization of the mitochondrial-membrane potential were observed. A pretreatment with the phosphatidylinositol-3-kinase (PI3K) inhibitor LY294002 markedly augmented the DNA damage caused by the cariporide, as indicated by a much greater extent of comet tails and a tail moment with increased levels of the p-histone H2A.X, p-ATMSer1981, p-ATRSer428, p-CHK1Ser345, and p-CHK2Thr68, as well as a series of pro-apoptotic events. The data suggest that an inhibition of the PI3K/AKT signaling is necessary to enhance the cytotoxicity toward the acid-tolerable H-2452AcT cells, and it underlines the significance of proton-pump targeting as a potential therapeutic strategy to overcome the acidic-microenvironment-associated chemotherapeutic resistance.

Knockdown of PKM2 and GLS1 expression can significantly reverse oxaliplatin-resistance in colorectal cancer cells

Clinical treatment for colorectal cancer (CRC) thus far encounters a huge challenge due to oxaliplatin-resistance. As crucial rate-limiting enzymes in aerobic glycolysis and glutaminolysis, pyruvate kinase M2 type (PKM2) and kidney-type glutaminase (GLS1) are proposed to carry important implications in colorectal carcinogenesis and drug-resistance. This study aimed to explore the possible association of oxaliplatin-resistance with aerobic glycolysis/glutaminolysis indexed by PKM2/GLS1 expression. PKM2 and GLS1 expression was quantified by polymerase chain reaction (PCR) and Western blot techniques in CRC cell lines. The abilities of cell formation, kinetics, migration, invasion, survival and apoptosis, as well as permeability glycoprotein (Pgp) expression were inspected before and after knocking-down PKM2/GLS1 expression. In addition, the influence of knocking-down PKM2/GLS1 expression was evaluated in vivo. Differentiated PKM2 and GLS1 expression in both THC8307 and THC8307/Oxa cell lines was identified. In the THC8307 cell line, PKM2 and GLS1 can accelerate malignant behaviors, increase oxaliplatin-resistance, upregulate Pgp expression, and inhibit cell apoptosis. Contrastingly in the THC8307/Oxa cell line, knockdown of PKM2/GLS1 expression can restrain malignant behaviors, reestablish oxaliplatin-sensitivity, downregulate Pgp expression, and induce cell apoptosis. In xenograft, knockdown of PKM2/GLS1 expression can significantly inhibit tumor growth, reduce Pgp expression, and increase tumor apoptosis. Taken together, the present findings enriched our knowledge by demonstrating a significant association of PKM2 and GLS1 with oxaliplatin-resistance in CRC. We further propose that knockdown of PKM2/GLS1 expression may constitute a novel therapeutic strategy toward effective treatment for CRC.