Extracellular pH Modulates Neuroendocrine Prostate Cancer Cell Metabolism and Susceptibility to the Mitochondrial Inhibitor Niclosamide

Antitumor activity of niclosamide-mediated oxidative stress against acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a heterogeneous clonal disease originated from B- or T-cell lymphoid precursor cells. ALL is often refractory or relapses after treatment. Novel treatments are anxiously needed in order to achieve a better response and prolonged overall survival in ALL patients. In the present study, we aimed at examining the antitumor effect of niclosamide on ALL. We investigated the effects of niclosamide on the proliferation and apoptosis in vitro, the growth of ALL cells in xenografted NOD-Prkdcem26Cd52 il2rgem26Cd22 /Nju (NCG) mice. The results showed that niclosamide treatment potently inhibited the growth of ALL cells and induced apoptosis via elevating the levels of reactive oxygen species and activating TP53. These findings suggest that niclosamide may be a promisingly potential agent for ALL therapy.

Carbon dioxide and MAPK signalling: towards therapy for inflammation

Inflammation, although necessary to fight infections, becomes a threat when it exceeds the capability of the immune system to control it. In addition, inflammation is a cause and/or symptom of many different disorders, including metabolic, neurodegenerative, autoimmune and cardiovascular diseases. Comorbidities and advanced age are typical predictors of more severe cases of seasonal viral infection, with COVID-19 a clear example. The primary importance of mitogen-activated protein kinases (MAPKs) in the course of COVID-19 is evident in the mechanisms by which cells are infected with SARS-CoV-2; the cytokine storm that profoundly worsens a patient's condition; the pathogenesis of diseases, such as diabetes, obesity, and hypertension, that contribute to a worsened prognosis; and post-COVID-19 complications, such as brain fog and thrombosis. An increasing number of reports have revealed that MAPKs are regulated by carbon dioxide (CO2); hence, we reviewed the literature to identify associations between CO2 and MAPKs and possible therapeutic benefits resulting from the elevation of CO2 levels. CO2 regulates key processes leading to and resulting from inflammation, and the therapeutic effects of CO2 (or bicarbonate, HCO3-) have been documented in all of the abovementioned comorbidities and complications of COVID-19 in which MAPKs play roles. The overlapping MAPK and CO2 signalling pathways in the contexts of allergy, apoptosis and cell survival, pulmonary oedema (alveolar fluid resorption), and mechanical ventilation-induced responses in lungs and related to mitochondria are also discussed. Video Abstract.

Sustained release of alpha-methylacyl-CoA racemase (AMACR) antibody-conjugated and free doxorubicin from silica nanoparticles for prostate cancer cell growth inhibition

This article presents silica nanoparticles for the sustained release of AMACR antibody-conjugated and free doxorubicin (DOX) for the inhibition of prostate cancer cell growth. Inorganic MCM-41 silica nanoparticles were synthesized, functionalized with phenylboronic acid groups (MCM-B), and capped with dextran (MCM-B-D). The nanoparticles were then characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, zeta potential analysis, nitrogen sorption, X-ray diffraction, and thermogravimetric analysis, before exploring their potential for drug loading and controlled drug release. This was done using a model prostate cancer drug, DOX, and a targeted prostate cancer drug, α-Methyl Acyl-CoA racemase (AMACR) antibody-conjugated DOX, which attaches specifically to AMACR proteins that are overexpressed on the surfaces of prostate cancer cells. The kinetics of sustained drug release over 30 days was then studied using zeroth order, first order, second order, Higuchi, and the Korsmeyer-Peppas models, while the thermodynamics of drug release was elucidated by determining the entropy and enthalpy changes. The flux of the released DOX was also simulated using the COMSOL Multiphysics software package. Generally, the AMACR antibody-conjugated DOX drug-loaded nanoparticles were more effective than the free DOX drug-loaded formulations in inhibiting the growth of prostate cancer cells in vitro over a 96 h period. The implications of the results are then discussed for the development of drug-eluting structures for the localized and targeted treatment of prostate cancer.

Constitutively Active Androgen Receptor in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the predominant type of liver cancer and a leading cause of cancer-related death globally. It is also a sexually dimorphic disease with a male predominance both in HCC and in its precursors, non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH). The role of the androgen receptor (AR) in HCC has been well documented; however, AR-targeted therapies have failed to demonstrate efficacy in HCC. Building upon understandings of AR in prostate cancer (PCa), this review examines the role of AR in HCC, non-androgen-mediated mechanisms of induced AR expression, the existence of AR splice variants (AR-SV) in HCC and concludes by surveying current AR-targeted therapeutic approaches in PCa that show potential for efficacy in HCC in light of AR-SV expression.

A simulation of parental and glycolytic tumor phenotype competition predicts observed responses to pH changes and increased glycolysis after anti-VEGF therapy

Clinical cancers are typically spatially and temporally heterogeneous, containing multiple microenvironmental habitats and diverse phenotypes and/or genotypes, which can interact through resource competition and direct or indirect interference. A common intratumoral evolutionary pathway, probably initiated as adaptation to hypoxia, leads to the "Warburg phenotype" which maintains high glycolytic rates and acid production, even in normoxic conditions. Since individual cancer cells are the unit of Darwinian selection, intraspecific competition dominates intratumoral evolution. Thus, elements of the Warburg phenotype become key "strategies" in competition with cancer cell populations that retain the metabolism of the parental normal cells. Here we model the complex interactions of cell populations with Warburg and parental phenotypes as they compete for access to vasculature, while subject to direct interference by Warburg-related acidosis. In this competitive environment, vasculature delivers nutrients, removes acid and necrotic detritus, and responds to signaling molecules (VEGF and TNF-α). The model is built in a nested fashion and growth parameters are derived from monolayer, spheroid, and xenograft experiments on prostate cancer. The resulting model of in vivo tumor growth reaches a steady state, displaying linear growth and coexistence of both glycolytic and parental phenotypes consistent with experimental observations. The model predicts that increasing tumor pH sufficiently early can arrest the development of the glycolytic phenotype, while decreasing tumor pH accelerates this evolution and increases VEGF production. The model's predicted dual effects of VEGF blockers in decreasing tumor growth while increasing the glycolytic fraction of tumor cells has potential implications for optimizing angiogenic inhibitors.

NRF2: A crucial regulator for mitochondrial metabolic shift and prostate cancer progression

Metabolic alterations are a common survival mechanism for prostate cancer progression and therapy resistance. Oxidative stress in the cellular and tumor microenvironment dictates metabolic switching in the cancer cells to adopt, prosper and escape therapeutic stress. Therefore, regulation of oxidative stress in tumor cells and in the tumor-microenvironment may enhance the action of conventional anticancer therapies. NRF2 is the master regulator for oxidative stress management. However, the overall oxidative stress varies with PCa clinical stage, metabolic state and therapy used for the cancer. In agreement, the blanket use of NRF2 inducers or inhibitors along with anticancer therapies cause adverse effects in some preclinical cancer models. In this review, we have summarized the levels of oxidative stress, metabolic preferences and NRF2 activity in the different stages of prostate cancer. We also propose condition specific ways to use NRF2 inducers or inhibitors along with conventional prostate cancer therapies. The significance of this review is not only to provide a detailed understanding of the mechanism of action of NRF2 to regulate oxidative stress-mediated metabolic switching by prostate cancer cells to escape the radiation, chemo, or hormonal therapies, and to grow aggressively, but also to provide a potential therapeutic method to control aggressive prostate cancer growth by stage specific proper use of NRF2 regulators.

Focus on the tumor microenvironment: A seedbed for neuroendocrine prostate cancer

The tumor microenvironment (TME) is a microecology consisting of tumor and mesenchymal cells and extracellular matrices. The TME plays important regulatory roles in tumor proliferation, invasion, metastasis, and differentiation. Neuroendocrine differentiation (NED) is a mechanism by which castration resistance develops in advanced prostate cancer (PCa). NED is induced after androgen deprivation therapy and neuroendocrine prostate cancer (NEPC) is established finally. NEPC has poor prognosis and short overall survival and is a major cause of death in patients with PCa. Both the cellular and non-cellular components of the TME regulate and induce NEPC formation through various pathways. Insights into the roles of the TME in NEPC evolution, growth, and progression have increased over the past few years. These novel insights will help refine the NEPC formation model and lay the foundation for the discovery of new NEPC therapies targeting the TME.

Detachment stress mediated bioenergetic switch of malignant melanoma cells into anti-Warburg phenotype

One of the biological features of cancer cells is their aerobic glycolysis by extensive glucose fermentation to harvest energy, so called Warburg effect. Melanoma is one of the most aggressive human cancers with poor prognosis and high mortality for its high metastatic ability. During the metastatic process, the metastatic tumor cells should survive under detachment stress. However, whether the detachment stress could affect the tumor phenotype is worthy to investigate.

We had established the cell model of human melanoma cells under detachment stress, which mimicked circulating melanoma. It had been demonstrated that the detachment stress altered melanoma cell activities, malignancy, and drug sensitivity. In this study, we found that adherent melanoma cells were more sensitive to glucose depletion. Gene expression profiling altered expressions of transporters associated with glucose metabolism. In addition, detachment stress reduced lactate secretion owing to the reduced MCT4 and GLUT1 expressions, the altered glycolytic and respiratory capacities, and the increased superoxide production. Detachment stress also increases the sensitivity of melanoma cells toward the blockade of electron transport chains. Investigation of the change in glucose metabolism of melanoma cells under detachment stress would be critical to provide a novel molecular mechanism to develop potential therapeutics.

Sorafenib and nitazoxanide disrupt mitochondrial function and inhibit regrowth capacity in three-dimensional models of hepatocellular and colorectal carcinoma

Quiescent cancer cells in malignant tumors can withstand cell-cycle active treatment and cause cancer spread and recurrence. Three-dimensional (3D) cancer cell models have led to the identification of oxidative phosphorylation (OXPHOS) as a context-dependent vulnerability. The limited treatment options for advanced hepatocellular carcinoma (HCC) and colorectal carcinoma (CRC) metastatic to the liver include the multikinase inhibitors sorafenib and regorafenib. Off-target effects of sorafenib and regorafenib are related to OXPHOS inhibition; however the importance of this feature to the effect on tumor cells has not been investigated in 3D models. We began by assessing global transcriptional responses in monolayer cell cultures, then moved on to multicellular tumor spheroids (MCTS) and tumoroids generated from a CRC patient. Cells were treated with chemotherapeutics, kinase inhibitors, and the OXPHOS inhibitors. Cells grown in 3D cultures were sensitive to the OXPHOS inhibitor nitazoxanide, sorafenib, and regorafenib and resistant to other multikinase inhibitors and chemotherapeutic drugs. Furthermore, nitazoxanide and sorafenib reduced viability, regrowth potential and inhibited mitochondrial membrane potential in an additive manner at clinically relevant concentrations. This study demonstrates that the OXPHOS inhibition caused by sorafenib and regorafenib parallels 3D activity and can be further investigated for new combination strategies.

Density Functional Theory Investigation of the Biocatalytic Mechanisms of pH-Driven Biomimetic Behavior in CeO2

There is considerable interest in the pH-dependent, switchable, biocatalytic properties of cerium oxide (CeO₂) nanoparticles in biomedicine, where these materials exhibit beneficial antioxidant activity against reactive oxygen species (ROS) at a basic physiological pH but cytotoxic prooxidant activity in an acidic cancer cell pH microenvironment. While the general characteristics of the role of oxygen vacancies are known, the mechanism of their action at the atomic scale under different pH conditions has yet to be elucidated. The present work applies density functional theory (DFT) calculations to interpret, at the atomic scale, the pH-induced behavior of the stable {111} surface of CeO₂ containing oxygen vacancies. Analysis of the surface-adsorbed media species reveals the critical role of pH on the interaction between ROS (^•O₂^- and H₂O₂) and the defective CeO₂ {111} surface. Under basic conditions, the superoxide dismutase (SOD) and catalase (CAT) biomimetic reactions can be performed cyclically, scavenging and decomposing ROS to harmless products, making CeO₂ an excellent antioxidant. However, under acidic conditions, the CAT biomimetic reaction is hindered owing to the limited reversibility of Ce³⁺ ↔ Ce⁴⁺ and formation ↔ annihilation of oxygen vacancies. A Fenton biomimetic reaction (H₂O₂ + Ce³⁺ → Ce⁴⁺ + OH^- + ^•OH) is predicted to occur simultaneously with the SOD and CAT biomimetic reactions, resulting in the formation of hydroxyl radicals, making CeO₂ a cytotoxic prooxidant.

Impact of cancer metabolism on therapy resistance - Clinical implications

Despite an increasing arsenal of anticancer therapies, many patients continue to have poor outcomes due to the therapeutic failures and tumor relapses. Indeed, the clinical efficacy of anticancer therapies is markedly limited by intrinsic and/or acquired resistance mechanisms that can occur in any tumor type and with any treatment. Thus, there is an urgent clinical need to implement fundamental changes in the tumor treatment paradigm by the development of new experimental strategies that can help to predict the occurrence of clinical drug resistance and to identify alternative therapeutic options. Apart from mutation-driven resistance mechanisms, tumor microenvironment (TME) conditions generate an intratumoral phenotypic heterogeneity that supports disease progression and dismal outcomes. Tumor cell metabolism is a prototypical example of dynamic, heterogeneous, and adaptive phenotypic trait, resulting from the combination of intrinsic [(epi)genetic changes, tissue of origin and differentiation dependency] and extrinsic (oxygen and nutrient availability, metabolic interactions within the TME) factors, enabling cancer cells to survive, metastasize and develop resistance to anticancer therapies. In this review, we summarize the current knowledge regarding metabolism-based mechanisms conferring adaptive resistance to chemo-, radio-and immunotherapies as well as targeted therapies. Furthermore, we report the role of TME-mediated intratumoral metabolic heterogeneity in therapy resistance and how adaptations in amino acid, glucose, and lipid metabolism support the growth of therapy-resistant cancers and/or cellular subpopulations. We also report the intricate interplay between tumor signaling and metabolic pathways in cancer cells and discuss how manipulating key metabolic enzymes and/or providing dietary changes may help to eradicate relapse-sustaining cancer cells. Finally, in the current era of personalized medicine, we describe the strategies that may be applied to implement metabolic profiling for tumor imaging, biomarker identification, selection of tailored treatments and monitoring therapy response during the clinical management of cancer patients.

Two diverse carriers are better than one: A case study in α‐particle therapy for prostate specific membrane antigen‐expressing prostate cancers

Partial and/or heterogeneous irradiation of established (i.e., large, vascularized) tumors by α‐particles that exhibit only a 4–5 cell‐diameter range in tissue, limits the therapeutic effect, since regions not being hit by the high energy α‐particles are likely not to be killed. This study aims to mechanistically understand a delivery strategy to uniformly distribute α‐particles within established solid tumors by simultaneously delivering the same α‐particle emitter by two diverse carriers, each killing a different region of the tumor: (1) the cancer‐agnostic, but also tumor‐responsive, liposomes engineered to best irradiate tumor regions far from the vasculature, and (2) a separately administered, antibody, targeting any cancer‐cell's surface marker, to best irradiate the tumor perivascular regions. We demonstrate that on a prostate specific membrane antigen (PSMA)‐expressing prostate cancer xenograft mouse model, for the same total injected radioactivity of the α‐particle emitter Actinium‐225, any radioactivity split ratio between the two carriers resulted in better tumor growth inhibition compared to the tumor inhibition when the total radioactivity was delivered by any of the two carriers alone. This finding was due to more uniform tumor irradiation for the same total injected radioactivity. The killing efficacy was improved even though the tumor‐absorbed dose delivered by the combined carriers was lower than the tumor‐absorbed dose delivered by the antibody alone. Studies on spheroids with different receptor‐expression, used as surrogates of the tumors' avascular regions, demonstrated that our delivery strategy is valid even for as low as 1+ (ImmunoHistoChemistry score) PSMA‐levels. The findings presented herein may hold clinical promise for those established tumors not being effectively eradicated by current α‐particle radiotherapies.

ARVib suppresses growth of advanced prostate cancer via inhibition of androgen receptor signaling

Targeting androgen signaling with the second-generation anti-androgen drugs, such as enzalutamide (Enza), abiraterone (Abi), apalutamide (Apal), and darolutamide (Daro), is the mainstay for the treatment of castration-resistant prostate cancer (CRPC). While these treatments are effective initially, resistance occurs frequently. Continued expression of androgen receptor (AR) and its variants such as AR-V7 despite AR-targeted therapy contributes to treatment resistance and cancer progression in advanced CRPC patients. This highlights the need for new strategies blocking continued AR signaling. Here, we identify a novel AR/AR-V7 degrader (ARVib) and found that ARVib effectively degrades AR/AR-V7 protein and attenuates AR/AR-V7 downstream target gene expression in prostate cancer cells. Mechanistically, ARVib degrades AR/AR-V7 protein through the ubiquitin-proteasome pathway mediated by HSP70/STUB1 machinery modulation. ARVib suppresses HSP70 expression and promotes STUB1 nuclear translocation, where STUB1 binds to AR/AR-V7 and promotes its ubiquitination and degradation. ARVib significantly inhibits resistant prostate tumor growth and improves enzalutamide treatment in vitro and in vivo. These data suggest that ARVib has potential for development as an AR/AR-V7 degrader to treat resistant CRPC.

Development and evaluation of inhalable composite niclosamide-lysozyme particles: A broad-spectrum, patient-adaptable treatment for coronavirus infections and sequalae

Niclosamide (NIC) has demonstrated promising in vitro antiviral efficacy against SARS-CoV-2, the causative agent of the COVID-19 pandemic. Though NIC is already FDA-approved, administration of the currently available oral formulation results in systemic drug levels that are too low for the inhibition of SARS-CoV-2. We hypothesized that the co-formulation of NIC with an endogenous protein, human lysozyme (hLYS), could enable the direct aerosol delivery of the drug to the respiratory tract as an alternative to oral delivery, thereby effectively treating COVID-19 by targeting the primary site of SARS-CoV-2 acquisition and spread. To test this hypothesis, we engineered and optimized composite particles containing NIC and hLYS suitable for delivery to the upper and lower airways via dry powder inhaler, nebulizer, and nasal spray. The novel formulation demonstrates potent in vitro and in vivo activity against two coronavirus strains, MERS-CoV and SARS-CoV-2, and may offer protection against methicillin-resistance staphylococcus aureus pneumonia and inflammatory lung damage occurring secondary to SARS-CoV-2 infections. The suitability of the formulation for all stages of the disease and low-cost development approach will ensure rapid clinical development and wide-spread utilization.

The Stone Guest: How Does pH Affect Binding Properties of PD-1/PD-L1 Inhibitors?

The interaction between programmed cell death-1 (PD-1) and its ligand PD-L1 activates a coinhibitory signal that blocks T-cell activation, promoting the immune escape process in the tumor microenvironment. Development of monoclonal antibodies targeting and inhibiting PD-1/PD-L1 interaction as anticancer immunotherapies has proved successful in multiple clinical settings and for various types of cancer. Notwithstanding, limitations exist with the use of these biologics, including drug resistance and narrow therapeutic response rate in a majority of patients, that demand for the design of more efficacious small molecule-based immunotherapies. Alteration of pH in the tumor microenvironment is a key factor that is involved in promoting drug resistance, tumor survival and progression. In this study, we have investigated the effect of pH shifts on binding properties of distinct classes of PD-L1 inhibitors, including macrocyclic peptide and small molecules. Results expand structure-activity relationships of PD-L1 inhibitors, providing insights into structural features and physicochemical properties that are useful for the design of ligands that may escape a drug resistance mechanism associated to variable pH conditions of tumor microenvironment.

New drugs are not enough‑drug repositioning in oncology: An update

Drug repositioning refers to the concept of discovering novel clinical benefits of drugs that are already known for use treating other diseases. The advantages of this are that several important drug characteristics are already established (including efficacy, pharmacokinetics, pharmacodynamics and toxicity), making the process of research for a putative drug quicker and less costly. Drug repositioning in oncology has received extensive focus. The present review summarizes the most prominent examples of drug repositioning for the treatment of cancer, taking into consideration their primary use, proposed anticancer mechanisms and current development status.

MCT1, MCT4 and CD147 expression and 3-bromopyruvate toxicity in colorectal cancer cells are modulated by the extracellular conditions

Monocarboxylate transporters (MCTs) inhibition leads to disruption in glycolysis, induces cell death and decreases cell invasion, revealing the importance of MCT activity in intracellular pH homeostasis and tumor aggressiveness. 3-Bromopyruvate (3BP) is an anti-tumor agent, whose uptake occurs via MCTs. It was the aim of this work to unravel the importance of extracellular conditions on the regulation of MCTs and in 3BP activity. HCT-15 was found to be the most sensitive cell line, and also the one that presented the highest basal expression of both MCT1 and of its chaperone CD147. Glucose starvation and hypoxia induced an increased resistance to 3BP in HCT-15 cells, in contrast to what happens with an extracellular acidic pH, where no alterations in 3BP cytotoxicity was observed. However, no association with MCT1, MCT4 and CD147 expression was observed, except for glucose starvation, where a decrease in CD147 (but not of MCT1 and MCT4) was detected. These results show that 3BP cytotoxicity might include other factors beyond MCTs. Nevertheless, treatment with short-chain fatty acids (SCFAs) increased the expression of MCT4 and CD147 as well as the sensitivity of HCT-15 cells to 3BP. The overall results suggest that MCTs influence the 3BP effect, although they are not the only players in its mechanism of action.

Intra/Extracellular Lactic Acid Exhaustion for Synergistic Metabolic Therapy and Immunotherapy of Tumors

Regulating the tumor microenvironment (TME) has been a promising strategy to improve antitumor therapy. Here, a red blood cell membrane (mRBC)-camouflaged hollow MnO₂ (HMnO₂ ) catalytic nanosystem embedded with lactate oxidase (LOX) and a glycolysis inhibitor (denoted as PMLR) is constructed for intra/extracellular lactic acid exhaustion as well as synergistic metabolic therapy and immunotherapy of tumor. Benefiting from the long-circulation property of the mRBC, the nanosystem can gradually accumulate in a tumor site through the enhanced permeability and retention (EPR) effect. The extracellular nanosystem consumes lactic acid in the TME by catalyzing its oxidation reaction via LOX. Meanwhile, the intracellular nanosystem releases the glycolysis inhibitor to cut off the source of lactic acid, as well as achieve antitumor metabolic therapy through the blockade of the adenosine triphosphate (ATP) supply. Both the extracellular and intracellular processes can be sensitized by O₂ , which can be produced during the decomposition of endogenous H₂ O₂ catalyzed by the PMLR nanosystem. The results show that the PMLR nanosystem can ceaselessly remove lactic acid, and then lead to an immunocompetent TME. Moreover, this TME regulation strategy can effectively improve the antitumor effect of anti-PDL1 therapy without the employment of any immune agonists to avoid the autoimmunity.

Inhibition of the key metabolic pathways, glycolysis and lipogenesis, of oral cancer by bitter melon extract

BACKGROUND

Metabolic reprogramming is one of the hallmarks of cancer which favours rapid energy production, biosynthetic capabilities and therapy resistance. In our previous study, we showed bitter melon extract (BME) prevents carcinogen induced mouse oral cancer. RNA sequence analysis from mouse tongue revealed a significant modulation in "Metabolic Process" by altering glycolysis and lipid metabolic pathways in BME fed group as compared to cancer group. In present study, we evaluated the effect of BME on glycolysis and lipid metabolism pathways in human oral cancer cells.

METHODS

Cal27 and JHU022 cells were treated with BME. RNA and protein expression were analysed for modulation of glycolytic and lipogenesis genes by quantitative real-time PCR, western blot analyses and immunofluorescence. Lactate and pyruvate level was determined by GC/MS. Extracellular acidification and glycolytic rate were measured using the Seahorse XF analyser. Shotgun lipidomics in Cal27 and JHU022 cell lines following BME treatment was performed by ESI/ MS. ROS was measured by FACS.

RESULTS

Treatment with BME on oral cancer cell lines significantly reduced mRNA and protein expression levels of key glycolytic genes SLC2A1 (GLUT-1), PFKP, LDHA, PKM and PDK3. Pyruvate and lactate levels and glycolysis rate were reduced in oral cancer cells following BME treatment. In lipogenesis pathway, we observed a significant reduction of genes involves in fatty acid biogenesis, ACLY, ACC1 and FASN, at the mRNA and protein levels following BME treatment. Further, BME treatment significantly reduced phosphatidylcholine, phosphatidylethanolamine, and plasmenylethanolamine, and reduced iPLA2 activity. Additionally, BME treatment inhibited lipid raft marker flotillin expression and altered its subcellular localization. ER-stress associated CHOP expression and generation of mitochondrial reactive oxygen species were induced by BME, which facilitated apoptosis.

CONCLUSION

Our study revealed that bitter melon extract inhibits glycolysis and lipid metabolism and induces ER and oxidative stress-mediated cell death in oral cancer. Thus, BME-mediated metabolic reprogramming of oral cancer cells will have important preventive and therapeutic implications along with conventional therapies.

Spatiotemporal pH Heterogeneity as a Promoter of Cancer Progression and Therapeutic Resistance

Dysregulation of pH in solid tumors is a hallmark of cancer. In recent years, the role of altered pH heterogeneity in space, between benign and aggressive tissues, between individual cancer cells, and between subcellular compartments, has been steadily elucidated. Changes in temporal pH-related processes on both fast and slow time scales, including altered kinetics of bicarbonate-CO₂ exchange and its effects on pH buffering and gradual, progressive changes driven by changes in metabolism, are further implicated in phenotypic changes observed in cancers. These discoveries have been driven by advances in imaging technologies. This review provides an overview of intra- and extracellular pH alterations in time and space reflected in cancer cells, as well as the available technology to study pH spatiotemporal heterogeneity.

Discovery of niclosamide and its O-alkylamino-tethered derivatives as potent antibacterial agents against carbapenemase-producing and/or colistin resistant Enterobacteriaceae isolates

Carbapenemase-producing Enterobacteriaceae (CPE) represents the most worrisome evolution of the antibiotic resistance crisis, which is almost resistant to most of available antibiotics. This situation is getting even worse particularly due to the recent emergence of colistin resistance. Herein, niclosamide, an FDA-approved traditional drug, and its novel O-alkylamino-tethered derivatives were discovered as new and potent antibacterial agents against carbapenemase-producing and/or colistin resistant Enterobacteriaceae isolates. Among these molecules, compound 10 (HJC0431) with 4-aminobutyl moiety showed the broad antibacterial activities, effective against 6 strains. In vitro checkerboard and time-kill course studies demonstrated the synergistic effects of the screened compounds with colistin against the corresponding strains with various degrees.

pH low insertion peptide mediated cell division cycle-associated protein 1 -siRNA transportation for prostatic cancer therapy targeted to the tumor microenvironment

Prostate cancer (PCa) is a common malignancy in male urinary system. Cell division cycle-associated protein 1 (CDCA1) is expressed highly in many cancer cells. Yet, whether CDCA1 play an important role in PCa progression is uncertain. pH low insertion peptide (pHLIP), a PH-induced transmembrane structure, can pass through the cell membrane into intracellular in an acidic environment. In this study, we try to confirm the expression status of CDCA1 in the PCa patients' tissues and PCa cell line. In addition, to make the CDCA1-siRNA efficiently targeting the PCa cells, pHLIP and CDCA1-siRNA were combined with disulfide bond to become effector molecules. By the characteristics of the pHLIP allosteric occurring in cancer tissue acidic microenvironment, CDCA1-siRNA may be transported specificity into prostatic cancer cells and released in the cytoplasm. The interference effect of the effector molecules on the CDCA1 was detected in vitro and in vivo. The results showed that CDCA1 was highly expressed in PCa cell line and human PCa clinical samples. Knock down CDCA1 significantly inhibit the growth and promote the apoptosis of prostatic cancer cells. In the intracellular translocation experiment, CDCA1-siRNA could be delivered into cytoplasma at pH 6.2, but not at pH 7.4. In the in vivo test, the tumor size was reduced obviously in the NOD/SCID mice treated with pHLIP-CDCA1-siRNA compared to the CDCA1-siRNA and the bioluminescent signal of Cy5-pHLIP-CDCA1-siRNA was focused detected in the tumor site. Our findings indicated that CDCA1 might be a very key molecule regulating survival and proliferation of PCa. pHLIP-CDCA1-siRNA might be a promising targeting therapy for PCa.

Cancer cell specific inhibition of Wnt/β-catenin signaling by forced intracellular acidification

Use of the diabetes type II drug Metformin is associated with a moderately lowered risk of cancer incidence in numerous tumor entities. Studying the molecular changes associated with the tumor-suppressive action of Metformin we found that the oncogene SOX4, which is upregulated in solid tumors and associated with poor prognosis, was induced by Wnt/β-catenin signaling and blocked by Metformin. Wnt signaling inhibition by Metformin was surprisingly specific for cancer cells. Unraveling the underlying specificity, we identified Metformin and other Mitochondrial Complex I (MCI) inhibitors as inducers of intracellular acidification in cancer cells. We demonstrated that acidification triggers the unfolded protein response to induce the global transcriptional repressor DDIT3, known to block Wnt signaling. Moreover, our results suggest that intracellular acidification universally inhibits Wnt signaling. Based on these findings, we combined MCI inhibitors with H⁺ ionophores, to escalate cancer cells into intracellular hyper-acidification and ATP depletion. This treatment lowered intracellular pH both in vitro and in a mouse xenograft tumor model, depleted cellular ATP, blocked Wnt signaling, downregulated SOX4, and strongly decreased stemness and viability of cancer cells. Importantly, the inhibition of Wnt signaling occurred downstream of β-catenin, encouraging applications in treatment of cancers caused by APC and β-catenin mutations.

Electrical Impedance Measurements of Biological Cells in Response to External Stimuli

Dielectric spectroscopy (DS) is a noninvasive technique for real-time measurements of the impedance spectra of biological cells. DS enables characterization of cellular dielectric properties such as membrane capacitance and cytoplasmic conductivity. We have developed a lab-on-a-chip device that uses an electro-activated microwells array for capturing, DS measurements, and unloading of biological cells. Impedance measurements were conducted at 0.2 V in the 10 kHz to 40 MHz range with 6 s time resolution. An equivalent circuit model was developed to extract the cell membrane capacitance and cell cytoplasmic conductivity from the impedance spectra. A human prostate cancer cell line, PC-3, was used to evaluate the device performance. Suspension of PC-3 cells in low conductivity buffers (LCB) enhanced their dielectrophoretic trapping and impedance response. We report the time course of the variations in dielectric properties of PC-3 cells suspended in LCB and their response to sudden pH change from a pH of 7.3 to a pH of 5.8. Importantly, we demonstrated that our device enabled real-time measurements of dielectric properties of live cancer cells and allowed the assessment of the cellular response to variations in buffer conductivity and pH. These data support further development of this device toward single cell measurements.

Effect of mitochondrial uncouplers niclosamide ethanolamine (NEN) and oxyclozanide on hepatic metastasis of colon cancer

Metabolism of cancer cells is characterized by aerobic glycolysis, or the Warburg effect. Aerobic glycolysis reduces pyruvate flux into mitochondria, preventing a complete oxidation of glucose and shunting glucose to anabolic pathways essential for cell proliferation. Here we tested a new strategy, mitochondrial uncoupling, for its potential of antagonizing the anabolic effect of aerobic glycolysis and for its potential anticancer activities. Mitochondrial uncoupling is a process that facilitates proton influx across the mitochondrial inner membrane without generating ATP, stimulating a futile cycle of acetyl- CoA oxidation. We tested two safe mitochondrial uncouplers, NEN (niclosamide ethanolamine) and oxyclozanide, on their metabolic effects and anti-cancer activities. We used metabolomic NMR to examine the effect of mitochondrial uncoupling on glucose metabolism in colon cancer MC38 cells. We further tested the anti-cancer effect of NEN and oxyclozanide in cultured cell models, APCmin/+ mouse model, and a metastatic colon cancer mouse model. Using a metabolomic NMR approach, we demonstrated that mitochondrial uncoupling promotes pyruvate influx to mitochondria and reduces various anabolic pathway activities. Moreover, mitochondrial uncoupling inhibits cell proliferation and reduces clonogenicity of cultured colon cancer cells. Furthermore, oral treatment with mitochondrial uncouplers reduces intestinal polyp formation in APCmin/+ mice, and diminishes hepatic metastasis of colon cancer cells transplanted intrasplenically. Our data highlight a unique approach for targeting cancer cell metabolism for cancer prevention and treatment, identified two prototype compounds, and shed light on the anti-cancer mechanism of niclosamide.

Coordinate effects of P2X7 and extracellular acidification in microglial cells

Extracellular adenosine 5′-triphosphate (ATP) is a damage-associated molecular pattern and contributes to inflammation associated diseases including cancer. Extracellular acidosis is a novel danger signal in the inflammatory sites, where it can modulate inflammation, immunity and tumor growth. Extracellular acidification was shown to inhibit P2X7-mediated channel currents, while it remains unknown how acidification and P2X7 together affect cellular responses. Here, we treated BV-2 microglial cells with ATP in a short period (<15 min) or a sustained acidified condition. For short acidification we compared the actions of neutralized ATP and acidic ATP in a condition with pH buffering. For sustained acidification, we treated cells with neutralized ATP in acidic medium or acidic ATP in medium without pH buffering. In the short acidified condition, neutralized ATP induced higher responses than acidic ATP to increase intracellular calcium and reactive oxygen species, decrease intracellular potassium and induce cell death. In contrast, these cellular responses and mitochondrial fission caused by neutralized ATP were enhanced by pH 6.0 and pH 4.5 media. P2X7 activation can also rapidly block mitochondrial ATP turnover and respiration capacity, both of which were mimicked by nigericin and enhanced by acidity. Taken together P2X7-mediated ionic fluxes and reactive oxygen species production are attenuated under short acidification, while sustained acidification itself can induce mitochondrial toxicity which deteriorates the mitochondrial function under P2X7 activation.

Extracellular acidification induces ROS- and mPTP-mediated death in HEK293 cells

The extracellular pH (pHe) is a key determinant of the cellular (micro)environment and needs to be maintained within strict boundaries to allow normal cell function. Here we used HEK293 cells to study the effects of pHe acidification (24 h), induced by mitochondrial inhibitors (rotenone, antimycin A) and/or extracellular HCl addition. Lowering pHe from 7.2 to 5.8 reduced cell viability by 70% and was paralleled by a decrease in cytosolic pH (pHc), hyperpolarization of the mitochondrial membrane potential (Δψ), increased levels of hydroethidine-oxidizing ROS and stimulation of protein carbonylation. Co-treatment with the antioxidant α-tocopherol, the mitochondrial permeability transition pore (mPTP) desensitizer cyclosporin A and Necrostatin-1, a combined inhibitor of Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) and Indoleamine 2,3-dioxygenase (IDO), prevented acidification-induced cell death. In contrast, the caspase inhibitor zVAD.fmk and the ferroptosis inhibitor Ferrostatin-1 were ineffective. We conclude that extracellular acidification induces necroptotic cell death in HEK293 cells and that the latter involves intracellular acidification, mitochondrial functional impairment, increased ROS levels, mPTP opening and protein carbonylation. These findings suggest that acidosis of the extracellular environment (as observed in mitochondrial disorders, ischemia, acute inflammation and cancer) can induce cell death via a ROS- and mPTP opening-mediated pathogenic mechanism.

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Extracellular acidification induces mitochondrial dysfunction.

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Extracellular acidification increases intracellular ROS levels.

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Extracellular acidification stimulates protein carbonylation.

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Extracellular acidification induces mPTP opening- and ROS-dependent cell death.

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Acidosis-induced oxidative stress likely contributes to various pathologies.

The antihelminthic drug niclosamide effectively inhibits the malignant phenotypes of uveal melanoma in vitro and in vivo

Uveal melanoma (UM) is a lethal intraocular malignancy with an average survival of only 2~8 months in patients with hepatic metastasis. Currently, there is no effective therapy for metastatic UM. Here, we reported that niclosamide, an effective repellence of tapeworm that has been approved for use in patients for approximately 50 years, exhibited strong antitumor activity in UM cells in vitro and in vivo. We showed that niclosamide potently inhibited UM cell proliferation, induced apoptosis and reduced migration and invasion. p-Niclosamide, a water-soluble niclosamide, exerted potent in vivo antitumor activity in a UM xenograft mouse model. Mechanistically, niclosamide abrogated the activation of the NF-κB pathway induced by tumor necrosis factor α (TNFα) in UM cells, while niclosamide elevated the levels of intracellullar and mitochondrial reactive oxygen species (ROS) in UM cells. Quenching ROS by N-acetylcysteine (NAC) weakened the ability of niclosamide-mediated apoptosis. Matrix metalloproteinase 9 (MMP-9) knockdown by shRNA potentiated, while ectopic expression of MMP-9 rescued, the niclosamide-attenuated invasion, implying that MMP-9 is pivotal for invasion blockage by niclosamide in UM cells. Furthermore, our results showed that niclosamide eliminated cancer stem-like cells (CSCs) as reflected by a decrease in the Aldefluor⁺ percentage and serial re-plating melanosphere formation, and these phenotypes were associated with the suppressed Wnt/β-catenin pathway by niclosamide in UM. Niclosamide caused a dose- and time-dependent reduction of β-catenin and the key components [e.g., DVLs, phospho-GSK3β (S9), c-Myc and Cyclin D1] in the canonical Wnt/β-catenin pathway. Additionally, niclosamide treatment in UM cells reduced ATP and cAMP contents, and decreased PKA-dependent phosphorylation of β-catenin at S552 and S675 which determine the stability of β-catenin protein, suggesting that niclosamide may work as a mitochondrial un-coupler. Taken together, our results shed light on the mechanism of antitumor action of niclosamide and warrant clinical trial for treatment of UM patients.

[Histopathologic studies on epithelial proliferation in the peripheral region of the lung with special consideration of tumorlets]

Niclosamide is an oral antihelminthic drug used to treat parasitic infections in millions of people worldwide. However recent studies have indicated that niclosamide may have broad clinical applications for the treatment of diseases other than those caused by parasites. These diseases and symptoms may include cancer, bacterial and viral infection, metabolic diseases such as Type II diabetes, NASH and NAFLD, artery constriction, endometriosis, neuropathic pain, rheumatoid arthritis, sclerodermatous graft-versus-host disease, and systemic sclerosis. Among the underlying mechanisms associated with the drug actions of niclosamide are uncoupling of oxidative phosphorylation, and modulation of Wnt/β-catenin, mTORC1, STAT3, NF-κB and Notch signaling pathways. Here we provide a brief overview of the biological activities of niclosamide, its potential clinical applications, and its challenges for use as a new therapy for systemic diseases.

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Niclosamide is an oral antihelminthic drug used to treat parasitic infections.

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Niclosamide is a multifunctional drug inhibiting multiple signaling pathways and biological processes.

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Niclosamide has biological activities potentially against systemic diseases.