Cancer: fundamentals behind pH targeting and the double-edged approach

Exploring monocarboxylate transporter inhibition for cancer treatment

Cells are separated from the environment by a lipid bilayer membrane that is relatively impermeable to solutes. The transport of ions and small molecules across this membrane is an essential process in cell biology and metabolism. Monocarboxylate transporters (MCTs) belong to a vast family of solute carriers (SLCs) that facilitate the transport of certain hydrophylic small compounds through the bilipid cell membrane. The existence of 446 genes that code for SLCs is the best evidence of their importance. In-depth research on MCTs is quite recent and probably promoted by their role in cancer development and progression. Importantly, it has recently been realized that these transporters represent an interesting target for cancer treatment. The search for clinically useful monocarboxylate inhibitors is an even more recent field. There is limited pre-clinical and clinical experience with new inhibitors and their precise mechanism of action is still under investigation. What is common to all of them is the inhibition of lactate transport. This review discusses the structure and function of MCTs, their participation in cancer, and old and newly developed inhibitors. Some suggestions on how to improve their anticancer effects are also discussed.

The Role of Tumor Metabolic Reprogramming in Tumor Immunity

The occurrence and development of tumors require the metabolic reprogramming of cancer cells, namely the alteration of flux in an autonomous manner via various metabolic pathways to meet increased bioenergetic and biosynthetic demands. Tumor cells consume large quantities of nutrients and produce related metabolites via their metabolism; this leads to the remodeling of the tumor microenvironment (TME) to better support tumor growth. During TME remodeling, the immune cell metabolism and antitumor immune activity are affected. This further leads to the escape of tumor cells from immune surveillance and therefore to abnormal proliferation. This review summarizes the regulatory functions associated with the abnormal biosynthesis and activity of metabolic signaling molecules during the process of tumor metabolic reprogramming. In addition, we provide a comprehensive description of the competition between immune cells and tumor cells for nutrients in the TME, as well as the metabolites required for tumor metabolism, the metabolic signaling pathways involved, and the functionality of the immune cells. Finally, we summarize current research targeted at the development of tumor immunotherapy. We aim to provide new concepts for future investigations of the mechanisms underlying the metabolic reprogramming of tumors and explore the association of these mechanisms with tumor immunity.

Targeting cancer metabolic pathways for improving chemotherapy and immunotherapy

Recent discoveries in cancer metabolism have revealed promising metabolic targets to modulate cancer progression, drug response, and anti-cancer immunity. Combination therapy, consisting of metabolic inhibitors and chemotherapeutic or immunotherapeutic agents, offers new opportunities for improved cancer therapy. However, it also presents challenges due to the complexity of cancer metabolic pathways and the metabolic interactions between tumor cells and immune cells. Many studies have been published demonstrating potential synergy between novel inhibitors of metabolism and chemo/immunotherapy, yet our understanding of the underlying mechanisms remains limited. Here, we review the current strategies of altering the metabolic pathways of cancer to improve the anti-cancer effects of chemo/immunotherapy. We also note the need to differentiate the effect of metabolic inhibition on cancer cells and immune cells and highlight nanotechnology as an emerging solution. Improving our understanding of the complexity of the metabolic pathways in different cell populations and the anti-cancer effects of chemo/immunotherapy will aid in the discovery of novel strategies that effectively restrict cancer growth and augment the anti-cancer effects of chemo/immunotherapy.

Innovative Design of Targeted Nanoparticles: Polymer-Drug Conjugates for Enhanced Cancer Therapy

Polymer-drug conjugates (PDCs) have shown great promise in enhancing the efficacy and safety of cancer therapy. These conjugates combine the advantageous properties of both polymers and drugs, leading to improved pharmacokinetics, controlled drug release, and targeted delivery to tumor tissues. This review provides a comprehensive overview of recent developments in PDCs for cancer therapy. First, various types of polymers used in these conjugates are discussed, including synthetic polymers, such as poly(↋-caprolactone) (PCL), D-α-tocopheryl polyethylene glycol (TPGS), and polyethylene glycol (PEG), as well as natural polymers such as hyaluronic acid (HA). The choice of polymer is crucial to achieving desired properties, such as stability, biocompatibility, and controlled drug release. Subsequently, the strategies for conjugating drugs to polymers are explored, including covalent bonding, which enables a stable linkage between the polymer and the drug, ensuring controlled release and minimizing premature drug release. The use of polymers can extend the circulation time of the drug, facilitating enhanced accumulation within tumor tissues through the enhanced permeability and retention (EPR) effect. This, in turn, results in improved drug efficacy and reduced systemic toxicity. Moreover, the importance of tumor-targeting ligands in PDCs is highlighted. Various ligands, such as antibodies, peptides, aptamers, folic acid, herceptin, and HA, can be incorporated into conjugates to selectively deliver the drug to tumor cells, reducing off-target effects and improving therapeutic outcomes. In conclusion, PDCs have emerged as a versatile and effective approach to cancer therapy. Their ability to combine the advantages of polymers and drugs offers enhanced drug delivery, controlled release, and targeted treatment, thereby improving the overall efficacy and safety of cancer therapies. Further research and development in this field has great potential to advance personalized cancer treatment options.

Drug Repurposing to Circumvent Immune Checkpoint Inhibitor Resistance in Cancer Immunotherapy

Immune checkpoint inhibitors (ICI) have achieved unprecedented clinical success in cancer treatment. However, drug resistance to ICI therapy is a major hurdle that prevents cancer patients from responding to the treatment or having durable disease control. Drug repurposing refers to the application of clinically approved drugs, with characterized pharmacological properties and known adverse effect profiles, to new indications. It has also emerged as a promising strategy to overcome drug resistance. In this review, we summarized the latest research about drug repurposing to overcome ICI resistance. Repurposed drugs work by either exerting immunostimulatory activities or abolishing the immunosuppressive tumor microenvironment (TME). Compared to the de novo drug design strategy, they provide novel and affordable treatment options to enhance cancer immunotherapy that can be readily evaluated in the clinic. Biomarkers are exploited to identify the right patient population to benefit from the repurposed drugs and drug combinations. Phenotypic screening of chemical libraries has been conducted to search for T-cell-modifying drugs. Genomics and integrated bioinformatics analysis, artificial intelligence, machine and deep learning approaches are employed to identify novel modulators of the immunosuppressive TME.

Exploitation of Proximity-Mediated Effects in Drug Discovery: An Update of Recent Research Highlights in Perturbing Pathogenic Proteins and Correlated Issues

The utilization of proximity-mediated effects to perturb pathogenic proteins of interest (POIs) has emerged as a powerful strategic alternative to conventional drug design approaches based on target occupancy. Over the past three years, the burgeoning field of targeted protein degradation (TPD) has witnessed the expansion of degradable POIs to membrane-associated, extracellular, proteasome-resistant, and even microbial proteins. Beyond TPD, researchers have achieved the proximity-mediated targeted protein stabilization, the recruitment of intracellular immunophilins to disturb undruggable targets, and the nonphysiological post-translational modifications of POIs. All of these strides provide new avenues for innovative drug discovery aimed at battling human malignancies and other major diseases. This perspective presents recent research highlights and discusses correlated issues in developing therapeutic modalities that exploit proximity-mediated effects to modulate pathogenic proteins, thereby guiding future academic and industrial efforts in this field.

Diversity and complexity of cell death: a historical review

Death is the inevitable fate of all living organisms, whether at the individual or cellular level. For a long time, cell death was believed to be an undesirable but unavoidable final outcome of nonfunctioning cells, as inflammation was inevitably triggered in response to damage. However, experimental evidence accumulated over the past few decades has revealed different types of cell death that are genetically programmed to eliminate unnecessary or severely damaged cells that may damage surrounding tissues. Several types of cell death, including apoptosis, necrosis, autophagic cell death, and lysosomal cell death, which are classified as programmed cell death, and pyroptosis, necroptosis, and NETosis, which are classified as inflammatory cell death, have been described over the years. Recently, several novel forms of cell death, namely, mitoptosis, paraptosis, immunogenic cell death, entosis, methuosis, parthanatos, ferroptosis, autosis, alkaliptosis, oxeiptosis, cuproptosis, and erebosis, have been discovered and advanced our understanding of cell death and its complexity. In this review, we provide a historical overview of the discovery and characterization of different forms of cell death and highlight their diversity and complexity. We also briefly discuss the regulatory mechanisms underlying each type of cell death and the implications of cell death in various physiological and pathological contexts. This review provides a comprehensive understanding of different mechanisms of cell death that can be leveraged to develop novel therapeutic strategies for various diseases.

Curcuminoids as Anticancer Drugs: Pleiotropic Effects, Potential for Metabolic Reprogramming and Prospects for the Future

The number of published studies on curcuminoids in cancer research, including its lead molecule curcumin and synthetic analogs, has been increasing substantially during the past two decades. Insights on the diversity of inhibitory effects they have produced on a multitude of pathways involved in carcinogenesis and tumor progression have been provided. As this wealth of data was obtained in settings of various experimental and clinical data, this review first aimed at presenting a chronology of discoveries and an update on their complex in vivo effects. Secondly, there are many interesting questions linked to their pleiotropic effects. One of them, a growing research topic, relates to their ability to modulate metabolic reprogramming. This review will also cover the use of curcuminoids as chemosensitizing molecules that can be combined with several anticancer drugs to reverse the phenomenon of multidrug resistance. Finally, current investigations in these three complementary research fields raise several important questions that will be put among the prospects for the future research related to the importance of these molecules in cancer research.

pH-Selective Reactions to Selectively Reduce Cancer Cell Proliferation: Effect of CaS Nanostructures in Human Skin Melanoma and Benign Fibroblasts

An acidic extracellular pH value (pHe) is characteristic of many cancers, in contrast to the physiologic pHe found in most benign cells. This difference in pH offers a unique opportunity to design and engineer chemicals that can be employed for pH-selective reactions in the extracellular fluid of cancer cells. The viability of human skin melanoma and corresponding fibroblasts exposed to CaS dispersions is reported. The viability of melanoma cells decreases with CaS dispersion concentration and reaches 57% at 3%, a value easily distinguishable from melanoma control experiments. In contrast, the viability of benign fibroblasts remains nearly constant within experimental error over the range of dispersion concentrations studied. The CaS dispersions facilitate vinculin delocalization in the cytoplasmic fluid, a result consistent with improved focal adhesion kinase (FAK) regulation in melanoma cells. Thermodynamic considerations are consistent with the formation ofH 2 S from CaS in the presence of protons. The thermodynamic prediction is verified in independent experiments with solid CaS and acidic aqueous solutions. The amount ofH 2 S formed decreases with pH. An activation energy for the process of (30 ± 10) kJ/mol in the temperature range of 280 to 330 K is estimated from initial rate measurements as a function of temperature. The total Gibbs energy minimization approach was employed to establish the distribution of sulfides-includingH 2 S in the gas and aqueous phases-from the dissociation of CaS as a function of pH to mimic physiologically relevant pH values. Theoretical calculations suggest that partially protonated CaS in solution can be stable until the sulfur atom bonds to two hydrogen atoms, resulting in the formation of Ca2+ andH 2 S , which can be solvated and/or released to the gas phase. Our results are consistent with a model in which CaS is dissociated in the extracellular fluid of melanoma cells selectively. The results are discussed in the context of the potential biomedical applications of CaS dispersions in cancer therapies.

Whole-cell energy modeling reveals quantitative changes of predicted energy flows in RAS mutant cancer cell lines

Cellular utilization of available energy flows to drive a multitude of forms of cellular "work" is a major biological constraint. Cells steer metabolism to address changing phenotypic states but little is known as to how bioenergetics couples to the richness of processes in a cell as a whole. Here, we outline a whole-cell energy framework that is informed by proteomic analysis and an energetics-based gene ontology. We separate analysis of metabolic supply and the capacity to generate high-energy phosphates from a representation of demand that is built on the relative abundance of ATPases and GTPases that deliver cellular work. We employed mouse embryonic fibroblast cell lines that express wild-type KRAS or oncogenic mutations and with distinct phenotypes. We observe shifts between energy-requiring processes. Calibrating against Seahorse analysis, we have created a whole-cell energy budget with apparent predictive power, for instance in relation to protein synthesis.

Exploiting the Acidic Extracellular pH: Evaluation of Streptococcus salivarius M18 Postbiotics to Target Cancer Cells

Previously, we showed that the growth, antibiotic resistance, and biofilm formation properties of the pathogens Pseudomonas aeruginosa and Klebsiella pneumonia were tremendously inhibited by the cell-free supernatant of the oral probiotic Streptococcus salivarius M18. These anti-pathogenic activities of the supernatant were more efficient under acidic conditions. The present approach takes advantage of the acidic nature of the tumor microenvironment to evaluate the effect of the S. salivarius M18 postbiotics on colon cancer cells. In both two-dimensional (2D) and three-dimensional (3D) cell culture models, S. salivarius M18 cell-free supernatant showed anti-cancer actions in the pH conditions mimicking the acidity of the tumor. The inhibitory effect was more prominent when the colon cancer cells have been treated with the cell-free supernatant obtained from the inulin incubated S. salivarius M18. The results of this study point out the potential of the S. salivarius M18 functional probiotic products to be used for targeting low pH environments including the unique acidic microenvironment of tumors.

Molecular and Cellular Mechanisms of Propolis and Its Polyphenolic Compounds against Cancer

In recent years, interest in natural products such as alternative sources of pharmaceuticals for numerous chronic diseases, including tumors, has been renewed. Propolis, a natural product collected by honeybees, and polyphenolic/flavonoid propolis-related components modulate all steps of the cancer progression process. Anticancer activity of propolis and its compounds relies on various mechanisms: cell-cycle arrest and attenuation of cancer cells proliferation, reduction in the number of cancer stem cells, induction of apoptosis, modulation of oncogene signaling pathways, inhibition of matrix metalloproteinases, prevention of metastasis, anti-angiogenesis, anti-inflammatory effects accompanied by the modulation of the tumor microenvironment (by modifying macrophage activation and polarization), epigenetic regulation, antiviral and bactericidal activities, modulation of gut microbiota, and attenuation of chemotherapy-induced deleterious side effects. Ingredients from propolis also "sensitize" cancer cells to chemotherapeutic agents, likely by blocking the activation of the transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). In this review, we summarize the current knowledge related to the the effects of flavonoids and other polyphenolic compounds from propolis on tumor growth and metastasizing ability, and discuss possible molecular and cellular mechanisms involved in the modulation of inflammatory pathways and cellular processes that affect survival, proliferation, invasion, angiogenesis, and metastasis of the tumor.

Tumor acidity: From hallmark of cancer to target of treatment

Tumor acidity is one of the cancer hallmarks and is associated with metabolic reprogramming and the use of glycolysis, which results in a high intracellular lactic acid concentration. Cancer cells avoid acid stress major by the activation and expression of proton and lactate transporters and exchangers and have an inverted pH gradient (extracellular and intracellular pHs are acid and alkaline, respectively). The shift in the tumor acid-base balance promotes proliferation, apoptosis avoidance, invasiveness, metastatic potential, aggressiveness, immune evasion, and treatment resistance. For example, weak-base chemotherapeutic agents may have a substantially reduced cellular uptake capacity due to "ion trapping". Lactic acid negatively affects the functions of activated effector T cells, stimulates regulatory T cells, and promotes them to express programmed cell death receptor 1. On the other hand, the inversion of pH gradient could be a cancer weakness that will allow the development of new promising therapies, such as tumor-targeted pH-sensitive antibodies and pH-responsible nanoparticle conjugates with anticancer drugs. The regulation of tumor pH levels by pharmacological inhibition of pH-responsible proteins (monocarboxylate transporters, H+-ATPase, etc.) and lactate dehydrogenase A is also a promising anticancer strategy. Another idea is the oral or parenteral use of buffer systems, such as sodium bicarbonate, to neutralize tumor acidity. Buffering therapy does not counteract standard treatment methods and can be used in combination to increase effectiveness. However, the mechanisms of the anticancer effect of buffering therapy are still unclear, and more research is needed. We have attempted to summarize the basic knowledge about tumor acidity.

Radiodynamic therapy with CsI(na)@MgO nanoparticles and 5-aminolevulinic acid

Background

Radiodynamic therapy (RDT) holds the potential to overcome the shallow tissue penetration issue associated with conventional photodynamic therapy (PDT). To this end, complex and sometimes toxic scintillator–photosensitizer nanoconjugates are often used, posing barriers for large-scale manufacturing and regulatory approval.

Methods

Herein, we report a streamlined RDT strategy based on CsI(Na)@MgO nanoparticles and 5-aminolevulinic acid (5-ALA). 5-ALA is a clinically approved photosensitizer, converted to protoporphyrin IX (PpIX) in cancer cells’ mitochondria. CsI(Na)@MgO nanoparticles produce strong ~ 410 nm X-ray luminescence, which matches the Soret band of PpIX. We hypothesize that the CsI(Na)@MgO-and-5-ALA combination can mediate RDT wherein mitochondria-targeted PDT synergizes with DNA-targeted irradiation for efficient cancer cell killing. Because scintillator nanoparticles and photosensitizer are administered separately, the approach forgoes issues such as self-quenching or uncontrolled release of photosensitizers.

Results

When tested in vitro with 4T1 cells, the CsI(Na)@MgO and 5-ALA combination elevated radiation-induced reactive oxygen species (ROS), enhancing damages to mitochondria, DNA, and lipids, eventually reducing cell proliferation and clonogenicity. When tested in vivo in 4T1 models, RDT with the CsI(Na)@MgO and 5-ALA combination significantly improved tumor suppression and animal survival relative to radiation therapy (RT) alone. After treatment, the scintillator nanoparticles, made of low-toxic alkali and halide elements, were efficiently excreted, causing no detectable harm to the hosts.

Conclusions

Our studies show that separately administering CsI(Na)@MgO nanoparticles and 5-ALA represents a safe and streamlined RDT approach with potential in clinical translation.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01537-z.

Combination of Goniothalamin and Sol-Gel-Derived Bioactive Glass 45S5 Enhances Growth Inhibitory Activity via Apoptosis Induction and Cell Cycle Arrest in Breast Cancer Cells MCF-7

Background

Combination of natural products with chemically synthesised biomaterials as cancer therapy has attracted great interest lately. Hence, this study is aimed at investigating the combined effects of goniothalamin and bioactive glass 45S5 (GTN-BG) and evaluating their anticancer properties on human breast cancer cells MCF-7.

Methods

The BG 45S5 was prepared using the sol-gel process followed by characterisation using PSA, BET, SEM/EDS, XRD, and FTIR. The effects of GTN-BG on the proliferation of MCF-7 were assessed by MTT, PrestoBlue, and scratch wound assays. The cell cycle analysis, Annexin-FITC assay, and activation of caspase-3/7, caspase-8, and caspase-9 assays were determined to further explore its mechanism of action.

Results

The synthesised BG 45S5 was classified as a fine powder, having a rough surface, and contains mesopores of 12.6 nm. EDS analysis revealed that silica and calcium elements are the primary components of BG powders. Both crystalline and amorphous structures were detected with 73% and 27% similarity to Na2Ca2(Si2O7) and hydroxyapatite, respectively. The combination of GTN-BG was more potent than GTN in inhibiting the proliferation of MCF-7 cells. G0/G1 and G2/M phases of the cell cycle were arrested by GTN and GTN-BG. The percentage of viable cells in GTN-BG treatment was significantly lower than that in GTN. In terms of activation of initiator caspases for both extrinsic and intrinsic apoptosis pathways, caspase-8 and caspase-9 were found more effective in response to GTN-BG than GTN.

Conclusion

The anticancer effect of GTN in MCF-7 cells was improved when combined with BG. The findings provide significant insight into the mechanism of GTN-BG against MCF-7 cells, which can potentially be used as a novel anticancer therapeutic approach.

Computational Prediction and Experimental Validation of the Unique Molecular Mode of Action of Scoulerine

Scoulerine is a natural compound that is known to bind to tubulin and has anti-mitotic properties demonstrated in various cancer cells. Its molecular mode of action has not been precisely known. In this work, we perform computational prediction and experimental validation of the mode of action of scoulerine. Based on the existing data in the Protein Data Bank (PDB) and using homology modeling, we create human tubulin structures corresponding to both free tubulin dimers and tubulin in a microtubule. We then perform docking of the optimized structure of scoulerine and find the highest affinity binding sites located in both the free tubulin and in a microtubule. We conclude that binding in the vicinity of the colchicine binding site and near the laulimalide binding site are the most likely locations for scoulerine interacting with tubulin. Thermophoresis assays using scoulerine and tubulin in both free and polymerized form confirm these computational predictions. We conclude that scoulerine exhibits a unique property of a dual mode of action with both microtubule stabilization and tubulin polymerization inhibition, both of which have similar affinity values.

Extracellular acidosis stimulates breast cancer cell motility through aryl hydrocarbon receptor and c-Src kinase activation

A reduction in extracellular pH (pHe) is a characteristic of most malignant tumors. The aryl hydrocarbon receptor (AhR) is a transcription factor localized in a cytosolic complex with c-Src, which allows it to trigger non-genomic effects through c-Src. Considering that the slightly acidic tumor microenvironment promotes breast cancer progression in a similar way to the AhR/c-Src axis, our aim was to evaluate whether this pathway could be activated by low pHe. We examined the effect of pHe 6.5 on AhR/c-Src axis using two breast cancer cell lines (MDA-MB-231 and LM3) and mammary epithelial cells (NMuMG) and found that acidosis increased c-Src phosphorylation only in tumor cells. Moreover, the presence of AhR inhibitors prevented c-Src activation. Low pHe reduced intracellular pH (pHi), while amiloride treatment, which is known to reduce pHi, induced c-Src phosphorylation through AhR. Analyses were conducted on cell migration and metalloproteases (MMP)-2 and -9 activities, with results showing an acidosis-induced increase in MDA-MB-231 and LM3 cell migration and MMP-9 activity, but no changes in NMuMG cells. Moreover, all these effects were blocked by AhR and c-Src inhibitors. In conclusion, acidosis stimulates the AhR/c-Src axis only in breast cancer cells, increasing cell migration and MMP-9 activity. Although the AhR activation mechanism still remains elusive, a reduction in pHi may be thought to be involved. These findings suggest a critical role for the AhR/c-Src axis in breast tumor progression stimulated by an acidic microenvironment. This article is protected by copyright. All rights reserved.

Targeting carbonic anhydrase IX and XII isoforms with small molecule inhibitors and monoclonal antibodies

Carbonic anhydrases IX and CAXII (CAIX/CAXII) are transmembrane zinc metalloproteins that catalyze a very basic but crucial physiological reaction: the conversion of carbon dioxide into bicarbonate with a release of the proton. CA, especially CAIX and CAXII isoforms gained the attention of many researchers interested in anticancer drug design due to pivotal functions of enzymes in the cancer cell metastasis and response to hypoxia, and their expression restricted to malignant cells. This offers an opportunity to develop new targeted therapies with fewer side effects. Continuous efforts led to the discovery of a series of diverse compounds with the most abundant sulphonamide derivatives. Here we review current knowledge considering small molecule and antibody-based targeting of CAIX/CAXII in cancer.

Metastasis and MAPK Pathways

Cancer is a leading cause of death worldwide. In many cases, the treatment of the disease is limited due to the metastasis of cells to distant locations of the body through the blood and lymphatic drainage. Most of the anticancer therapeutic options focus mainly on the inhibition of tumor cell growth or the induction of cell death, and do not consider the molecular basis of metastasis. The aim of this work is to provide a comprehensive review focusing on cancer metastasis and the mitogen-activated protein kinase (MAPK) pathway (ERK/JNK/P38 signaling) as a crucial modulator of this process.

Identification of Lactate-Related Gene Signature for Prediction of Progression and Immunotherapeutic Response in Skin Cutaneous Melanoma

Skin cutaneous melanoma (SKCM) is a skin cancer type characterized by a high degree of immune cell infiltration. The potential function of lactate, a main metabolic product in the tumor microenvironment (TME) of SKCM, remains unclear. In this study, we systemically analyzed the predictive value of lactate-related genes (LRGs) for prognosis and response to immune checkpoint inhibitors (ICIs) in SKCM patients included from The Cancer Genome Atlas (TCGA) database. Cluster 3, by consensus clustering for 61 LRGs, manifested a worse clinical outcome, attributed to the overexpression of malignancy marks. In addition, we created a prognostic prediction model for high- and low-risk patients and verified its performance in a validation cohort, GSE65904. Between TME and the risk model, we found a negative relation of the immunocyte infiltration levels with patients’ risk scores. The low-risk cases had higher ICI expression and could benefit better from ICIs relative to the high-risk cases. Thus, the lactate-related prognosis risk signature may comprehensively provide a basis for future investigations on immunotherapeutic treatment for SKCM.

Importance of T, NK, CAR T and CAR NK Cell Metabolic Fitness for Effective Anti-Cancer Therapy: A Continuous Learning Process Allowing the Optimization of T, NK and CAR-Based Anti-Cancer Therapies

Simple Summary

Cancer treatments are evolving at a very rapid pace. Some of the most novel anti-cancer medicines under development rely on the modification of immune cells in order to transform them into potent tumor-killing cells. However, the tumor microenvironment (TME) is competing for nutrients with these harnessed immune cells and therefore paralyzes their metabolic effective and active anti-cancer activities. Here we describe strategies to overcome these hurdles imposed on immune cell activity, which lead to therapeutic approaches to enhance metabolic fitness of the patient’s immune system with the objective to improve their anti-cancer capacity.

Abstract

Chimeric antigen receptor (CAR) T and CAR NK cell therapies opened new avenues for cancer treatment. Although original successes of CAR T and CAR NK cells for the treatment of hematological malignancies were extraordinary, several obstacles have since been revealed, in particular their use for the treatment of solid cancers. The tumor microenvironment (TME) is competing for nutrients with T and NK cells and their CAR-expressing counterparts, paralyzing their metabolic effective and active states. Consequently, this can lead to alterations in their anti-tumoral capacity and persistence in vivo. High glucose uptake and the depletion of key amino acids by the TME can deprive T and NK cells of energy and building blocks, which turns them into a state of anergy, where they are unable to exert cytotoxic activity against cancer cells. This is especially true in the context of an immune-suppressive TME. In order to re-invigorate the T, NK, CAR T and CAR NK cell-mediated antitumor response, the field is now attempting to understand how metabolic pathways might change T and NK responses and functions, as well as those from their CAR-expressing partners. This revealed ways to metabolically rewire these cells by using metabolic enhancers or optimizing pre-infusion in vitro cultures of these cells. Importantly, next-generation CAR T and CAR NK products might include in the future the necessary metabolic requirements by improving their design, manufacturing process and other parameters. This will allow the overcoming of current limitations due to their interaction with the suppressive TME. In a clinical setting, this might improve their anti-cancer effector activity in synergy with immunotherapies. In this review, we discuss how the tumor cells and TME interfere with T and NK cell metabolic requirements. This may potentially lead to therapeutic approaches that enhance the metabolic fitness of CAR T and CAR NK cells, with the objective to improve their anti-cancer capacity.

Stimuli-responsive nanomaterials for cancer treatment: boundaries, opportunities and applications

Small molecule drugs, including most chemotherapies, are rapidly degraded and/or eliminated from the body, which is why high doses of these drugs are necessary, potentially producing toxic effects. Several types of nanoparticles loaded with anti-cancer drugs have been designed to overcome the disadvantages of conventional therapies. Modified nanoparticles can circulate for a long time, thus improving the solubility and biodistribution of drugs. Furthermore, they also allow the controlled release of the payload once its target tissue has been reached. These mechanisms can reduce the exposure of healthy tissues to chemotherapeutics, since the drugs are only released in the presence of specific tumour stimuli. Overall, these properties can improve the effectiveness of treatments while reducing undesirable side effects. In this article, we review the recent advances in stimuli-responsive albumin, gold and magnetic nanostructures for controlled anti-cancer drug delivery. These nanostructures were designed to release drugs in response to different internal and external stimuli of the cellular environment, including pH, redox, light and magnetic fields. We also describe various examples of applications of these nanomaterials. Overall, we shed light on the properties, potential clinical translation and limitations of stimuli-responsive nanoparticles for cancer treatment.

Cytosine-Rich DNA Fragments Covalently Bound to Carbon Nanotube as Factors Triggering Doxorubicin Release at Acidic pH. A Molecular Dynamics Study

This works deals with analysis of properties of a carbon nanotube, the tips of which were functionalized by short cytosine-rich fragments of ssDNA. That object is aimed to work as a platform for storage and controlled release of doxorubicin in response to pH changes. We found that at neutral pH, doxorubicin molecules can be intercalated between the ssDNA fragments, and formation of such knots can effectively block other doxorubicin molecules, encapsulated in the nanotube interior, against release to the bulk. Because at the neutral pH, the ssDNA fragments are in form of random coils, the intercalation of doxorubicin is strong. At acidic pH, the ssDNA fragments undergo folding into i-motifs, and this leads to significant reduction of the interaction strength between doxorubicin and other components of the system. Thus, the drug molecules can be released to the bulk at acidic pH. The above conclusions concerning the storage/release mechanism of doxorubicin were drawn from the observation of molecular dynamics trajectories of the systems as well as from analysis of various components of pair interaction energies.

Breast cancer therapy affects the expression of antineonatal Nav1.5 antibodies in the serum of patients with breast cancer

Neonatal Nav1.5 (nNav1.5) is the alternative splice variant of Nav1.5 and it has been widely associated with the progression of breast cancer. The immunological context of nNav1.5 with respect to breast cancer metastases remains unexplored. The presence of antibodies against nNav1.5 may highlight the immunogenicity of nNav1.5. Hence, the aim of the present study was to detect the presence of antineonatal Nav1.5 antibodies (antinNav1.5-Ab) in the serum of patients with breast cancer and to elucidate the effects of breast cancer therapy on its expression. A total of 32 healthy female volunteers and 64 patients with breast cancer were randomly recruited into the present study as the control and breast cancer group, respectively. Patients with breast cancer were divided equally based on their pre- and ongoing-treatment status. Serum samples were tested with in-house indirect enzyme-linked immunosorbent assay (ELISA) to detect antinNav1.5-Ab, CD25 (T regulatory cell marker) using an ELISA kit and Luminex assay to detect the expression of metastasis-associated cytokines, such as vascular endothelial growth factor (VEGF), interleukin (IL)-6, IL-10, IL-8, chemokine (C-C motif) ligand 2 and tumor necrosis factor-alpha (TNF-α) The mean difference in the expression of antinNav1.5-Ab among the three groups (control, pretreatment and ongoing-treatment) was significant (P=0.0005) and the pretreatment breast cancer group exhibited the highest expression. The concentration of CD25 was highest in the pretreatment breast cancer group compared with the control and ongoing-treatment groups. There was a significant positive correlation between antinNav1.5-Ab and IL-6 in the pretreatment group (r=0.7260; P=0.0210) and a significant negative correlation between antinNav1.5-Ab and VEGF in the ongoing-treatment group (r=-0.842; P-value=0.0040). The high expression of antinNav1.5-Ab in the pretreatment group was in accordance with the uninterrupted presence of metastasis and highlighted the immunogenicity of nNav1.5 whereas the low expression of antinNav1.5-Ab in the ongoing-treatment group reflected the efficacy of breast cancer therapy in eliminating metastases. The augmented manifestation of T regulatory cells in the pretreatment group highlighted the functional role of nNav1.5 in promoting metastasis. The parallel expression of antinNav1.5-Ab with the imbalanced expression of cytokines promoting metastasis (IL-8, IL-6 and TNF-α) and cytokines that prevent metastasis (IL-10) indicated the role of nNav1.5 in breast cancer growth. The expression of antinNav1.5-Ab in accordance to the metastatic microenvironment indicates the immunogenicity of the protein and highlights the influence of breast cancer therapy on its expression level.

Effect of Calomelanone, a Dihydrochalcone Analogue, on Human Cancer Apoptosis/Regulated Cell Death in an In Vitro Model

Calomelanone, 2',6'-dihydroxy-4,4'-dimethoxydihydrochalcone, possesses anticancer activities. This study was conducted to investigate the cytotoxic effect of calomelanone, a dihydrochalcone analogue, on human cancer cells and its associated mechanisms. The cytotoxic effect of calomelanone was measured by MTT assay. Annexin V-FITC/propidium iodide and DiOC6 staining that employed flow cytometry were used to determine the mode of cell death and reduction of mitochondrial transmembrane potential (MTP), respectively. Caspase activities were measured using specific substrates and colorimetric analysis. The expression levels of Bcl-2 family proteins were determined by immunoblotting. Reactive oxygen species were also measured using 2',7'-dihydrodichlorofluorescein diacetate and dihydroethidium (fluorescence dyes). Calomelanone was found to be toxic towards various human cancer cells, including acute promyelocytic HL-60 and monocytic leukemic U937 cells, in a dose-dependent manner at 24 h and human hepatocellular HepG2 cells at 48 h. However, the proliferation of HepG2 cells increased at 24 h. Calomelanone was found to induce apoptosis in HL-60 and U937 at 24 h and HepG2 apoptosis at 48 h via the intrinsic pathway by inducing MTP disruption. This compound also induced caspase-3, caspase-8, and caspase-9 activities. Calomelanone upregulated proapoptotic Bax and Bak and downregulated antiapoptotic Bcl-xL proteins in HepG2 cells. Moreover, signaling was also associated with oxidative stress in HepG2 cells. Calomelanone induced autophagy at 24 h of treatment, which was evidenced by staining with monodansylcadaverine (MDC) to represent autophagic flux. This was associated with a decrease of Akt (survival pathway) and an upregulation of Atg5 (the marker of autophagy). Thus, calomelanone induced apoptosis/regulated cell death in HL-60, U937, and HepG2 cells. However, it also induced autophagy in HepG2 depending on duration, dose, and type of cells. Thus, calomelanone could be used as a potential anticancer agent for cancer treatment. Nevertheless, acute and chronic toxicity should be further investigated in animals before conducting investigations in human patients.

Targeting the pH Paradigm at the Bedside: A Practical Approach

The inversion of the pH gradient in malignant tumors, known as the pH paradigm, is increasingly becoming accepted by the scientific community as a hallmark of cancer. Accumulated evidence shows that this is not simply a metabolic consequence of a dysregulated behavior, but rather an essential process in the physiopathology of accelerated proliferation and invasion. From the over-simplification of increased lactate production as the cause of the paradigm, as initially proposed, basic science researchers have arrived at highly complex and far-reaching knowledge, that substantially modified that initial belief. These new developments show that the paradigm entails a different regulation of membrane transporters, electrolyte exchangers, cellular and membrane enzymes, water trafficking, specialized membrane structures, transcription factors, and metabolic changes that go far beyond fermentative glycolysis. This complex world of dysregulations is still shuttered behind the walls of experimental laboratories and has not yet reached bedside medicine. However, there are many known pharmaceuticals and nutraceuticals that are capable of targeting the pH paradigm. Most of these products are well known, have low toxicity, and are also inexpensive. They need to be repurposed, and this would entail shorter clinical studies and enormous cost savings if we compare them with the time and expense required for the development of a new molecule. Will targeting the pH paradigm solve the "cancer problem"? Absolutely not. However, reversing the pH inversion would strongly enhance standard treatments, rendering them more efficient, and in some cases permitting lower doses of toxic drugs. This article's goal is to describe how to reverse the pH gradient inversion with existing drugs and nutraceuticals that can easily be used in bedside medicine, without adding toxicity to established treatments. It also aims at increasing awareness among practicing physicians that targeting the pH paradigm would be able to improve the results of standard therapies. Some clinical cases will be presented as well, showing how the pH gradient inversion can be treated at the bedside in a simple manner with repurposed drugs.

Regulating Interactions Between Targeted Nanocarriers and Mononuclear Phagocyte System via an Esomeprazole-Based Preconditioning Strategy

Purpose

The mononuclear phagocyte system (MPS) presents a formidable obstacle that hampers the delivery of various nanopreparations to tumors. Therefore, there is an urgent need to improve the off-MPS targeting ability of nanomedicines. In the present study, we present a novel preconditioning strategy to substantially increase the circulation times and tumor targeting of nanoparticles by regulating nanocarrier-MPS interactions.

Methods

In vitro, the effect of different vacuolar H⁺-ATPase inhibitors on macrophage uptake of targeted or nontargeted lipid vesicles was evaluated. Specifically, the clinically approved proton-pump inhibitor esomeprazole (ESO) was selected as a preconditioning agent. Then, we further investigated the blocking effect of ESO on the macrophage endocytosis of nanocarriers. In vivo, ESO was first intravenously administered into A549-tumor-bearing nude mice, and 24 h later, the c(RGDm7)-modified vesicles co-loaded with doxorubicin and gefitinib were intravenously injected.

Results

In vitro, ESO was found to reduce the interactions between macrophages and c(RGDm7)-modified vesicles by interfering with the latter’s lysosomal trafficking. Studies conducted in vivo confirmed that ESO pretreatment greatly decreased the liver and spleen distribution of the targeted vesicles, enhanced their tumor accumulation, and improved the therapeutic outcome of the drug-loaded nanomedicines.

Conclusion

Our findings indicate that ESO can regulate the nanoparticle-MPS interaction, which provides a feasible option for enhancing the off-MPS targeting of nanomedicines.

Triggering doxorubicin release from responsive hydrogel films by polyamine uptake

Polyamines such as putrescine, spermidine and spermine are required in many inter- and intra-cellular processes. There is, however, evidence of anomalously high concentrations of these polyamines around cancer cells. Furthermore, high polyamine concentrations play a key role in accelerating the speed of cancer proliferation. Some current therapies target the reduction of the polyamine concentration to delay the cancer advance. In this study, we use a molecular theory to prove the concept that poly(methacrylic acid) (PMAA) hydrogels can play the dual role of incorporating and retaining polyamines as well as releasing preloaded drugs in response. Towards such a goal, we have developed a molecular model for each of the chemical species, which includes the shape, size, charge, protonation state, and configuration. Our results indicate that PMAA hydrogel films can incorporate significant amounts of polyamines; this absorption increases with the solution concentration of the polyamines. Doxorubicin was chosen as a model drug for this study, which can be successfully incorporated within the film; the optimal encapsulation conditions occur at low salt concentrations and pH values near neutral. Polyamine absorption within the film results in the desorption of the drug from the hydrogel. An increase in the concentration of the polyamines enhances the drug release. To validate our theoretical findings, poly(methacrylic acid) hydrogel thin films were synthesized by atom transfer radical polymerization. Absorption/desorption experiments followed by UV-Vis spectroscopy demonstrate doxorubicin encapsulation within these films and polyamine-dependent drug release.

Targeted Degradation of SLC Transporters Reveals Amenability of Multi-Pass Transmembrane Proteins to Ligand-Induced Proteolysis

With more than 450 members, the solute carrier (SLC) group of proteins represents the largest class of transporters encoded in the human genome. Their several-pass transmembrane domain structure and hydrophobicity contribute to the orphan status of many SLCs, devoid of known cargos or chemical inhibitors. We report that SLC proteins belonging to different families and subcellular compartments are amenable to induced degradation by heterobifunctional ligands. Engineering endogenous alleles via the degradation tag (dTAG) technology enabled chemical control of abundance of the transporter protein, SLC38A2. Moreover, we report the design of d9A-2, a chimeric compound engaging several members of the SLC9 family and leading to their degradation. d9A-2 impairs cellular pH homeostasis and promotes cell death in a range of cancer cell lines. These findings open the era of SLC-targeting chimeric degraders and demonstrate potential access of multi-pass transmembrane proteins of different subcellular localizations to the chemically exploitable degradation machinery.

Targeting Metabolism to Improve the Tumor Microenvironment for Cancer Immunotherapy

The growing field of immune metabolism has revealed promising indications for metabolic targets to modulate anti-cancer immunity. Combination therapies involving metabolic inhibitors with immune checkpoint blockade (ICB), chemotherapy, radiation, and/or diet now offer new approaches for cancer therapy. However, it remains uncertain how to best utilize these strategies in the context of the complex tumor microenvironment (TME). Oncogene-driven changes in tumor cell metabolism can impact the TME to limit immune responses and present barriers to cancer therapy. These changes also reveal opportunities to reshape the TME by targeting metabolic pathways to favor immunity. Here we explore current strategies that shift immune cell metabolism to pro-inflammatory states in the TME and highlight a need to better replicate physiologic conditions to select targets, clarify mechanisms, and optimize metabolic inhibitors. Unifying our understanding of these pathways and interactions within the heterogenous TME will be instrumental to advance this promising field and enhance immunotherapy.

Altered Iron Metabolism and Impact in Cancer Biology, Metastasis, and Immunology

Iron is an essential nutrient that plays a complex role in cancer biology. Iron metabolism must be tightly controlled within cells. Whilst fundamental to many cellular processes and required for cell survival, excess labile iron is toxic to cells. Increased iron metabolism is associated with malignant transformation, cancer progression, drug resistance and immune evasion. Depleting intracellular iron stores, either with the use of iron chelating agents or mimicking endogenous regulation mechanisms, such as microRNAs, present attractive therapeutic opportunities, some of which are currently under clinical investigation. Alternatively, iron overload can result in a form of regulated cell death, ferroptosis, which can be activated in cancer cells presenting an alternative anti-cancer strategy. This review focuses on alterations in iron metabolism that enable cancer cells to meet metabolic demands required during different stages of tumorigenesis in relation to metastasis and immune response. The strength of current evidence is considered, gaps in knowledge are highlighted and controversies relating to the role of iron and therapeutic targeting potential are discussed. The key question we address within this review is whether iron modulation represents a useful approach for treating metastatic disease and whether it could be employed in combination with existing targeted drugs and immune-based therapies to enhance their efficacy.

Tracking Gold Nanorods' Interaction with Large 3D Pancreatic-Stromal Tumor Spheroids by Multimodal Imaging: Fluorescence, Photoacoustic, and Photothermal Microscopies

Pancreatic cancer is one of the most complex types of cancers to detect, diagnose, and treat. However, the field of nanomedicine has strong potential to address such challenges. When evaluating the diffusion and penetration of theranostic nanoparticles, the extracellular matrix (ECM) is of crucial importance because it acts as a barrier to the tumor microenvironment. In the present study, the penetration of functionalized, fluorescent gold nanorods into large (>500 μm) multicellular 3D tissue spheroids was studied using a multimodal imaging approach. The spheroids were generated by co-culturing pancreatic cancer cells and pancreatic stellate cells in multiple ratios to mimic variable tumor-stromal compositions and to investigate nanoparticle penetration. Fluorescence live imaging, photothermal, and photoacoustic analysis were utilized to examine nanoparticle behavior in the spheroids. Uniquely, the nanorods are intrinsically photoacoustic and photothermal, enabling multi-imaging detection even when fluorescence tracking is not possible or ideal.

Serum bicarbonate is a marker of peri-operative mortality but is not associated with long term survival in colorectal cancer

AIMS

Inflammation is a hallmark of cancer whose activity is modulated within the tumor microenvironment by low tumoral pH. Recent evidence in the literature has suggested a link between low serum bicarbonate, low tumoral pH and cancer related inflammation. There is however little clinical evidence in human patients regarding the prognostic role of serum bicarbonate. Therefore, the primary aim of this study was to investigate the short and long-term prognostic utility of serum bicarbonate in colorectal cancer (CRC) patients undergoing resection of their primary tumor. The study also aimed to investigate the association of serum bicarbonate with known markers of systemic inflammation.

METHODS

A total of 3281 consecutive patients who underwent surgical resection of their primary CRC from January 1998 to December 2012. Of these, 2223 stage I-IV patients had available data for analysis. The association of serum bicarbonate with overall survival was assessed using univariate and multivariate cox regression analyses. The association of bicarbonate with other clinicopathological variables was assessed by chi squared and Fisher's exact tests.

RESULTS

Serum bicarbonate was associated with peri-operative mortality in multivariate analysis (p<0.001). Age (p = 0.004), grade (p = 0.043), creatinine (p = 0.036) and sodium (p = 0.036) were also markers associated with peri-operative mortality. For long term survival at 5 years, bicarbonate was significantly associated with overall survival in univariate analysis (p<0.001) but was not significant in multivariate analysis (p = 0.075). In exploratory analysis, serum bicarbonate was found to be significantly associated with the lymphocyte-to-monocyte ratio (p<0.001) and neutrophil-to-lymphocyte ratio (p<0.001).

CONCLUSIONS

In peri-operative colorectal cancer patients, serum bicarbonate was associated with 30-day survival but not 5-year survival.

Acidic Microenvironment Regulates the Severity of Hepatic Ischemia/Reperfusion Injury by Modulating the Generation and Function of Tregs via the PI3K-mTOR Pathway

Hepatic ischemia/reperfusion injury (HIRI) is a major cause of liver dysfunction and even liver failure after liver transplantation and hepatectomy. One of the critical mechanisms that lead to HIRI is an acidic microenvironment, which develops due to the accumulation of high acid-like substances such as lactic acid and ketone bodies. Previous studies have shown that the adoptive transfer of induced regulatory T cells (iTregs) attenuates HIRI; however, little is known about the function of Tregs in the acidic microenvironment of a HIRI model. In the present study, we examined the effect of acidic microenvironment on Tregs in vitro and in vivo. Here, we report that microenvironment acidification and dysfunction of the liver is induced during HIRI in humans and mice and that an acidic microenvironment can inhibit the generation and function of CD4⁺CD25⁺Foxp3⁺ iTregs via the PI3K/Akt/mTOR signaling pathway. By contrast, the reversal of the acidic microenvironment restored Foxp3 expression and iTreg function. In addition, the results of cell culture in vitro indicated that the proton pump inhibitor omeprazole improves decreased iTreg differentiation caused by the acidic microenvironment, suggesting the potential clinical use of proton pump inhibitors as immunoregulatory therapy in the treatment of HIRI. Furthermore, our findings demonstrate that buffering the acidic microenvironment to attenuate HIRI in mice has an inseparable relationship with Tregs. Thus, an acidic microenvironment is a key regulator in HIRI, involved in modulating the generation and function of Tregs.

Thermodynamics of cell penetrating peptides on lipid membranes: sequence and membrane acidity regulate surface binding

Acidic lipids respond to pH in ways that fully promote or deplete the surface accumulation of cell penetrating peptides.

Hydrogen Ion Dynamics of Cancer and a New Molecular, Biochemical and Metabolic Approach to the Etiopathogenesis and Treatment of Brain Malignancies

The treatment of cancer has been slowly but steadily progressing during the last fifty years. Some tumors with a high mortality in the past are curable nowadays. However, there is one striking exception: glioblastoma multiforme. No real breakthrough has been hitherto achieved with this tumor with ominous prognosis and very short survival. Glioblastomas, being highly glycolytic malignancies are strongly pH-dependent and driven by the sodium hydrogen exchanger 1 (NHE1) and other proton (H⁺) transporters. Therefore, this is one of those pathologies where the lessons recently learnt from the new pH-centered anticancer paradigm may soon bring a promising change to treatment. This contribution will discuss how the pH-centric molecular, biochemical and metabolic perspective may introduce some urgently needed and integral novel treatments. Such a prospective therapeutic approach for malignant brain tumors is developed here, either to be used alone or in combination with more standard therapies.

Type 1 Sodium Calcium Exchanger Forms a Complex with Carbonic Anhydrase IX and Via Reverse Mode Activity Contributes to pH Control in Hypoxic Tumors

Hypoxia and acidosis are among the key microenvironmental factors that contribute to cancer progression. We have explored a possibility that the type 1Na⁺/Ca²⁺ exchanger (NCX1) is involved in pH control in hypoxic tumors. We focused on changes in intracellular pH, co-localization of NCX1, carbonic anhydrase IX (CA IX), and sodium proton exchanger type 1 (NHE1) by proximity ligation assay, immunoprecipitation, spheroid formation assay and migration of cells due to treatment with KB-R7943, a selective inhibitor of the reverse-mode NCX1. In cancer cells exposed to hypoxia, reverse-mode NCX1 forms a membrane complex primarily with CA IX and also with NHE1. NCX1/CA IX/NHE1 assembly operates as a metabolon with a potent ability to extrude protons to the extracellular space and thereby facilitate acidosis. KB-R7943 prevents formation of this metabolon and reduces cell migration. Thus, we have shown that in hypoxic cancer cells, NCX1 operates in a reverse mode and participates in pH regulation in hypoxic tumors via cooperation with CAIX and NHE1.

Inflammation and Metabolism in Cancer Cell-Mitochondria Key Player

Cancer metabolism is an essential aspect of tumorigenesis, as cancer cells have increased energy requirements in comparison to normal cells. Thus, an enhanced metabolism is needed in order to accommodate tumor cells' accelerated biological functions, including increased proliferation, vigorous migration during metastasis, and adaptation to different tissues from the primary invasion site. In this context, the assessment of tumor cell metabolic pathways generates crucial data pertaining to the mechanisms through which tumor cells survive and grow in a milieu of host defense mechanisms. Indeed, various studies have demonstrated that the metabolic signature of tumors is heterogeneous. Furthermore, these metabolic changes induce the exacerbated production of several molecules, which result in alterations that aid an inflammatory milieu. The therapeutic armentarium for oncology should thus include metabolic and inflammation regulators. Our expanding knowledge of the metabolic behavior of tumor cells, whether from solid tumors or hematologic malignancies, may provide the basis for the development of tailor-made cancer therapies.

Extrinsic acidosis suppresses glycolysis and migration while increasing network formation in pulmonary microvascular endothelial cells

Acidosis is common among critically ill patients, but current approaches to correct pH do not improve disease outcomes. During systemic acidosis, cells are either passively exposed to extracellular acidosis that other cells have generated (extrinsic acidosis) or they are exposed to acid that they generate and export into the extracellular space (intrinsic acidosis). Although endothelial repair following intrinsic acidosis has been studied, the impact of extrinsic acidosis on migration and angiogenesis is unclear. We hypothesized that extrinsic acidosis inhibits metabolism and migration but promotes capillary-like network formation in pulmonary microvascular endothelial cells (PMVECs). Extrinsic acidosis was modeled by titrating media pH. Two types of intrinsic acidosis were compared, including increasing cellular metabolism by chemically inhibiting carbonic anhydrases (CAs) IX and XII (SLC-0111) and with hypoxia. PMVECs maintained baseline intracellular pH for 24 h with both extrinsic and intrinsic acidosis. Whole cell CA IX protein expression was decreased by extrinsic acidosis but not affected by hypoxia. When extracellular pH was equally acidic, extrinsic acidosis suppressed glycolysis, whereas intrinsic acidosis did not. Extrinsic acidosis suppressed migration, but increased Matrigel network master junction and total segment length. CRISPR-Cas9 CA IX knockout PMVECs revealed an independent role of CA IX in promoting glycolysis, as loss of CA IX alone was accompanied by decreased hexokinase I and pyruvate dehydrogenase E1α expression and decreasing migration. 2-deoxy-d-glucose had no effect on migration but profoundly inhibited network formation and increased N-cadherin expression. Thus, we report that while extrinsic acidosis suppresses endothelial glycolysis and migration, it promotes network formation.

Immune targets in the tumor microenvironment treated by radiotherapy

Radiotherapy (RT), the major anti-cancer modality for more than half of cancer patients after diagnosis, has the advantage of local tumor control with relatively less systematic side effects comparing to chemotherapy. However, the efficacy of RT is limited by acquired tumor resistance leading to the risks of relapse and metastasis. To further enhance the efficacy of RT, with the renaissances of targeted immunotherapy (TIT), increasing interests are raised on RT combined with TIT including cancer vaccines, T-cell therapy, and antibody-based immune checkpoint blockers (ICB) such as anti-CTLA-4 and anti-PD1/PD-L1. In achieving a significant synergy between RT and TIT, the dynamics of radiation-induced response in tumor cells and stromal cells, especially the cross-talk between tumor cells and immune cells in the irradiated tumor microenvironment (ITME) as highlighted in recent literature are to be elucidated. The abscopal effect refereeing the RT-induced priming function outside of ITME could be compromised by the immune-suppressive factors such as CD47 and PD-L1 on tumor cells and Treg induced or enhanced in the ITME. Cell surface receptors temporally or permanently induced and bioactive elements released from dead cells could serve antigenic source (radiation-associated antigenic proteins, RAAPs) to the host and have functions in immune regulation on the tumor. This review is attempted to summarize a cluster of factors that are inducible by radiation and targetable by antibodies, or have potential to be immune regulators to synergize tumor control with RT. Further characterization of immune regulators in ITME will deepen our understanding of the interplay among immune regulators in ITME and discover new effective targets for the combined modality with RT and TIT.

Selected Office Based Anticancer Treatment Strategies

Over the years, the treatment of patients with cancer has varied widely as much because of recent advancements in science and medicine as the philosophies that belie their use. This paper briefly describes many of the prevailing approaches in use today with an attempt to offer some perspective of how to apply these disparate methodologies so that they may be more effectively integrated, resulting in consistently better clinical responses.

Programmed pH/reduction-responsive nanoparticles for efficient delivery of antitumor agents in vivo

To bypass the biological barriers during the drug delivery process, it is desirable to develop smart nanoparticles (NPs) with flexible physical and chemical properties. In this study, a programmed NP delivery system with a pH-triggered detachable PEG layer and a lactobionic acid (Lac)-modified reduction-responsive core was developed to address the "PEG dilemma" and provide an on-demand intracellular release of doxorubicin (DOX). The positively charged DOX-loaded lactobionic acid-chitosan-lipoic acid (DOX/LCL) NPs were prepared and coated with a negatively charged dimethylmaleic acid-PEG-chitosan (PEG-CS-DA) layer to obtain a prolonged circulation time and improve the tumor-targeting effect. After reaching the tumor tissues through a targeted delivery effect, the surface charge of the PEG-CS-DA layer was reversed from negative to positive because of the trigger by the acidic microenvironment (pH 6.8), thus leading to the detachment of the PEG layer. The exposure of positive charges and the active targeting ligand enhanced cellular uptake and facilitated penetration into tumor tissues. Subsequently, the rapid release and diffusion of DOX into the nuclei was triggered by the intracellular high concentration of glutathione, thus leading to cell apoptosis. In conclusion, these programmed pH/reduction-responsive NPs provide a promising strategy for the delivery of antitumor agents in vivo. STATEMENT OF SIGNIFICANCE: In this study, novel programmed pH/reduction-responsive NPs were developed for the delivery of DOX in vivo. These NPs were coated with a negatively charged PEG layer to improve the serum stability and tumor target effect. The PEG layer detached because of the trigger by tumor acidic microenvironment (pH 6.8), thus leading to the exposure of positive charges and the active targeting ligand, which enhanced cellular uptake and facilitated penetration into tumor tissues. Subsequently, the rapid release of DOX was triggered by the intracellular high concentration of glutathione, thereby resulting in enhanced cytotoxicity. These programmed pH/reduction-responsive NPs provide a promising strategy for the delivery of antitumor agents in vivo.

PEG-b-poly (carbonate)-derived nanocarrier platform with pH-responsive properties for pancreatic cancer combination therapy

A pH-responsive nanoparticle platform, based on PEG-b-poly (carbonate) block copolymers have been proposed that can respond to low pH as found in many cancer micro- and intracellular environment, including that in pancreatic cancer. The hydrophobic domain, i.e., the poly (carbonate) segment has been substituted with tertiary amine side chains, such as N, N'-dibutylethylenediamine (pK_a = 4.0, DB) and 2-pyrrolidin-1-yl-ethyl-amine (pk_a = 5.4, Py) to generate two different sets of block copolymers namely PEG-DB and PEG-PY systems. These side-chain appended amines promote disassembly of nanoparticles and activation of drug release in response to pH conditions mimicking extra- (pH 6.9-6.5) and intracellular compartments (5.5-4.5, from early endosome to lysosome) of cancer tissues respectively. A frontline chemotherapy used for pancreatic cancer, i.e., gemcitabine (GEM) and a Hedgehog inhibitor (GDC 0449) has been used as the model combination to evaluate the encapsulation and pH-dependent release efficiency of these block copolymers. We found that, depending on the tertiary amine side chains appended to the polycarbonate segment, these block copolymers self-assemble to form nanoparticles with the size range of 100-150 nm (with a critical association concentration value in the order of 10^-6 M). We also demonstrated an approach where GEM and GDC 0449-encapsulated PEG-DB and PEG-PY nanoparticles, responsive to two different pH conditions, when mixed at a 1:1 vol ratio, yielded a pH-dependent co-release of the encapsulated contents. We envision that such release behaviour can be exploited to gain spatiotemporal control over drug accumulation in pathological compartments with different pH status. The mixture of pH-responsive nanoparticles was found to suppress pancreatic cancer cell proliferation when loaded with anticancer agents in vitro. Cell-proliferation assay showed that both variants of PEG-b-polycarbonate block copolymers were inherently non-toxic. We have also immobilized iRGD peptide on intracellularly activable PEG-DB systems to augment cellular uptake. These targeted nanoparticles were found to promote selective internalization of particles in pancreatic cancer cells and tumor tissue.

Effects of proton pump inhibitors on reversing multidrug resistance via downregulating V-ATPases/PI3K/Akt/mTOR/HIF-1α signaling pathway through TSC1/2 complex and Rheb in human gastric adenocarcinoma cells in vitro and in vivo

Background

Our study aimed to explore the effects of PPIs on reversing multidrug resistance (MDR) to chemotherapy in gastric cancer by inhibiting the expression of V-ATPases and the PI3K/Akt/mTOR/HIF-1α signal pathway.

Methods

The gastric cancer cell lines SGC7901 and the multidrug resistance cell lines SGC7901/MDR were pretreated by the pantoprazole or the esomeprazole, respectively. Real-time PCR was used to determine mRNA levels, and western blotting and immunofluorescent staining analyses were employed to determine the protein expressions and intracellular distributions of the V-ATPases, PI3K, Akt, mTOR, HIF-1α, P-gp and MRP1 before and after PPIs pretreatment. SGC7901/MDR cells were planted on the athymic nude mice. Then the effects of PPZ pretreatment and/or ADR were compared by determining the tumor size, tumor weight and nude mice weight.

Results

PPIs pretreatment could inhibit mRNA levels of V-ATPases, MDR1 and MRP1, PI3K, Akt, mTOR and HIF-1α. PPIs inhibited V-ATPases and down-regulated the expressions of P-gp and MRP1. And further to block the expression of mTOR by Rapamycin could obviously inhibit the expressions of HIF-1α, P-gp and MRP1 in a dose-dependent manner. Therefore, PPIs inhibited the expressions of V-ATPases and then reversed MDR of the chemotherapy in gastric cancer by inhibiting P-gp and MRP1, and it could be speculated that the mechanism might be closely related to down-regulating the PI3K/Akt/mTOR/HIF-1α signaling pathway. Meanwhile, PPIs also could inhibit the expressions of TSC1/TSC2 complex and Rheb which might be involved into regulating the signaling pathway intermediately. The weight growth rate of the mice bearing tumor in the treatment group was lower than that of the nude mice in the normal group, while the weight growth rate of the mice in control group was significantly lower than that of the normal group and the treatment group, presenting a downward trend.

Conclusion

Therefore, PPIs inhibited the expressions of V-ATPases and then reversed MDR of the chemotherapy in gastric cancer by inhibiting P-gp and MRP1, and it could be speculated that the mechanism might be closely related to down-regulating the PI3K/Akt/mTOR/HIF-1α signaling pathway, and also to inhibiting the expressions of TSC1/TSC2 complex and Rheb which might be involved into regulating the signaling pathway intermediately.