Acidosis promotes invasiveness of breast cancer cells through ROS-AKT-NF-κB pathway

Moringin, an isothiocyanate modulates multiple cellular signalling molecules in breast cancer cells

Prohibitin (PHB) is a pleiotropic molecule with a variety of known functions and subcellular locations. PHB's function in breast cancer is poorly understood. Herein, we report that PHB is expressed in cancer types of diverse origin including breast cancer. The cancer patients with changes in PHB were reported to have significantly reduced 'overall survival' in comparison to the cases without alterations in PHB. The expression of PHB was increased by H2O2 and also by Moringin (MG), which is an isothiocyanate derived from the seeds of Moringa oleifera. MG interacted with PHB, DRP1, and SLP2 and inhibited the growth of MCF-7 and MDAMB-231 cells. The isothiocyanate triggered apoptosis in breast cancer cells as revealed by AO/PI assay, phosphatidylserine externalization, cell cycle analysis and DAPI staining. MG induced proapoptotic proteins expression such as cytochrome c, p53, and cleaved caspase-7. Further, cell survival proteins such as survivin, Bcl-2, and Bcl-xL were suppressed. A depolarization of membrane potential suggested that the apoptosis was triggered through mitochondria. The isothiocyanate suppressed the cancer cell migration and interacted with NF-κB subunits. MG suppressed p65 nuclear translocation induced by TNF-α. The reactive oxygen species generation was also induced by the isothiocyanate in breast cancer cells. MG also modulated the expression of lncRNAs. Collectively, the functions of PHB in breast cancer growth is evident from this study. The activities of MG against breast cancer might result from its ability to modulate multiple cancer-related targets.

Acidosis activates breast cancer ferroptosis through ZFAND5/SLC3A2 signaling axis and elicits M1 macrophage polarization

Acidosis is involved in multiple pathways in tumor cells and immune cells among the tumor microenvironment (TME). Ferroptosis is a nonapoptotic and iron-dependent form of cell death characterized by accumulation of lipid peroxidation involved in various cancers. The role of ferroptosis in the breast cancer (BC) acidic microenvironment remains unrevealed. Here, we reported that short-term acidosis induced ferroptosis of BC cells in the zinc finger AN1-type domain 5 (ZFAND5)/solute carrier family 3 member 2 (SLC3A2) dependent manner to suppress tumor growth using in silico and multiple biological methods. Mechanistically, we demonstrated that short-term acidosis increased total/lipid reactive oxygen species (ROS) level, decreased glutathione (GSH) level and induced the morphological changes of mitochondria. Specifically, acidosis restrained the protein stability of SLC3A2 by promoting its ubiquitination process. The prognostic analysis showed that higher expression of ZFAND5 and lower expression of SLC3A2 were correlated with longer overall survival of BC patients, respectively. Furthermore, in combination with ferroptosis agonist metformin, short-term acidosis could synergistically inhibit viability and enhance the ferroptosis of BC cells. Meanwhile, by the exploration of immune cells, short-term acidosis also induced M1 macrophage polarization, triggering processes of phagocytosis and ferroptosis in BC cells. This study demonstrated that short-term acidosis induced BC cell ferroptosis through ZFAND5/SLC3A2 signaling axis and promoted phagocytosis and ferroptosis of BC cells with M1 macrophage polarization, which might be a new mechanism for BC therapy.

Immunotherapy Enhancement by Targeting Extracellular Tumor pH in Triple-Negative Breast Cancer Mouse Model

Triple-negative breast cancer (TNBC), as one of the most aggressive forms of breast cancer, is characterized by a poor prognosis and a very low rate of disease-free and overall survival. In recent years, immunotherapeutic approaches targeting T cell checkpoint molecules, such as cytotoxic lymphocyte antigen-4 (CTLA-4), programmed death1 (PD-1) or its ligand, programmed death ligand 1 (PD-L1), have shown great potential and have been used to treat various cancers as single therapies or in combination with other modalities. However, despite this remarkable progress, patients with TNBC have shown a low response rate to this approach, commonly developing resistance to immune checkpoint blockade, leading to treatment failure. Extracellular acidosis within the tumor microenvironment (also known as the Warburg effect) is one of the factors preventing immune cells from mounting effective responses and contributing to immunotherapy treatment failure. Therefore, reducing tumor acidity is important for increasing cancer immunotherapy effectiveness and this has yet to be realized in the TNBC environment. In this study, the oral administration of sodium bicarbonate (NaHCO3) enhanced the antitumor effect of anti-PD-L1 antibody treatment, as demonstrated by generated antitumor immunity, tumor growth inhibition and enhanced survival in 4T1-Luc breast cancer model. Here, we show that NaHCO3 increased extracellular pH (pHe) in tumor tissues in vivo, an effect that was accompanied by an increase in T cell infiltration, T cell activation and IFN-γ, IL2 and IL12p40 mRNA expression in tumor tissues, as well as an increase in T cell activation in tumor-draining lymph nodes. Interestingly, these changes were further enhanced in response to combined NaHCO3 + anti-PD-L1 therapy. In addition, the acidic extracellular conditions caused a significant increase in PD-L1 expression in vitro. Taken together, these results indicate that alkalizing therapy holds potential as a new tumor microenvironment immunomodulator and we hypothesize that NaHCO3 can enhance the antitumor effects of anti-PD-L1 breast cancer therapy. The combination of these treatments may have an exceptional impact on future TNBC immunotherapeutic approaches by providing a powerful personalized medicine paradigm. Therefore, our findings have a great translational potential for improving outcomes in TNBC patients.

Genome-wide association study of mammary gland tumors in Maltese dogs

Background

A genome-wide association study (GWAS) is a valuable tool for investigating genetic and phenotypic variation in many diseases.

Objective

The objective of this study was to identify variations in the genomes of Maltese dogs that are associated with the mammary gland tumor (MGT) phenotype and to assess the association between each biological condition and MGT phenotype in Maltese dogs.

Methods

DNA was extracted from 22 tumor samples and 11 whole blood samples from dogs with MGTs. Genome-wide single-nucleotide polymorphism (SNP) genotyping was performed, and the top 20 SNPs associated with various conditions and genetic variations were mapped to their corresponding gene locations.

Results

The genotyping process successfully identified 173,662 loci, with an overall genotype completion rate of 99.92%. Through the quality control analysis, 46,912 of these SNPs were excluded. Allelic tests were conducted to generate Manhattan plots, which showed several significant SNPs associated with MGT phenotype in intergenic region. The most prominent SNP, located within a region associated with transcription and linked to the malignancy grade of MGT, was identified on chromosome 5 (p = 0.00001) though there may be lack of statistical significance. Other SNPs were also found in several genes associated with oncogenesis, including TNFSF18, WDR3, ASIC5, STAR, and IL1RAP.

Conclusion

To our knowledge, this is the first GWAS to analyze the genetic predisposition to MGT in Maltese dogs. Despite the limited number of cases, these analyzed data could provide the basis for further research on the genetic predisposition to MGTs in Maltese dogs.

Anticancer Effect of Gallic Acid on Acidity-Induced Invasion of MCF7 Breast Cancer Cells

The acidic tumor environment has emerged as a crucial factor influencing the metastatic potential of cancer. We investigated the effect of an acidic environment on the acquisition of metastatic properties in MCF7 breast cancer cells and explored the inhibitory effects of gallic acid. Prolonged exposure to acidic culture conditions (over 12 weeks at pH 6.4) induced the acquisition of migratory and invasive properties in MCF7 cells, accompanied by increased expression of Matrix Metalloproteinase 2 and 9 (MMP2 and MMP9, respectively), together with alterations in E-cadherin, vimentin, and epithelial-to-mesenchymal transition markers. Gallic acid effectively inhibited the survival of acidity-adapted MCF7 (MCF7-6.4/12w) cells at high concentrations (>30 μM) and reduced metastatic characteristics induced by acidic conditions at low concentration ranges (5-20 μM). Moreover, gallic acid suppressed the PI3K/Akt pathway and the nuclear accumulation of β-catenin, which were elevated in MCF7-6.4/12w cells. These findings highlight the potential of gallic acid as a promising therapeutic agent for metastatic traits in breast cancer cells under acidic conditions.

RAGE/SNAIL1 signaling drives epithelial-mesenchymal plasticity in metastatic triple-negative breast cancer

Epithelial/Mesenchymal (E/M) plasticity plays a fundamental role both in embryogenesis and during tumorigenesis. The receptor for advanced glycation end products (RAGE) is a driver of cell plasticity in fibrotic diseases; however, its role and molecular mechanism in triple-negative breast cancer (TNBC) remains unclear. Here, we demonstrate that RAGE signaling maintains the mesenchymal phenotype of aggressive TNBC cells by enforcing the expression of SNAIL1. Besides, we uncover a crosstalk mechanism between the TGF-β and RAGE pathways that is required for the acquisition of mesenchymal traits in TNBC cells. Consistently, RAGE inhibition elicits epithelial features that block migration and invasion capacities. Next, since RAGE is a sensor of the tumor microenvironment, we modeled acute acidosis in TNBC cells and showed it promotes enhanced production of RAGE ligands and the activation of RAGE-dependent invasive properties. Furthermore, acute acidosis increases SNAIL1 levels and tumor cell invasion in a RAGE-dependent manner. Finally, we demonstrate that in vivo inhibition of RAGE reduces metastasis incidence and expands survival, consistent with molecular effects that support the relevance of RAGE signaling in E/M plasticity. These results uncover new molecular insights on the regulation of E/M phenotypes in cancer metastasis and provide rationale for pharmacological intervention of this signaling axis.

NF-κB mediated regulation of tumor cell proliferation in hypoxic microenvironment

Hypoxia is caused by a cancer-promoting milieu characterized by persistent inflammation. NF-κB and HIF-1α are critical participants in this transition. Tumor development and maintenance are aided by NF-κB, while cellular proliferation and adaptability to angiogenic signals are aided by HIF-1α. Prolyl hydroxylase-2 (PHD-2) has been hypothesized to be the key oxygen-dependent regulator of HIF-1α and NF-transcriptional B's activity. Without low oxygen levels, HIF-1α is degraded by the proteasome in a process dependent on oxygen and 2-oxoglutarate. As opposed to the normal NF-κB activation route, where NF-κB is deactivated by PHD-2-mediated hydroxylation of IKK, this method actually activates NF-κB. HIF-1α is protected from degradation by proteasomes in hypoxic cells, where it then activates transcription factors involved in cellular metastasis and angiogenesis. The Pasteur phenomenon causes lactate to build up inside the hypoxic cells. As part of a process known as lactate shuttle, MCT-1 and MCT-4 cells help deliver lactate from the blood to neighboring, non-hypoxic tumour cells. Non-hypoxic tumour cells use lactate, which is converted to pyruvate, as fuel for oxidative phosphorylation. OXOPHOS cancer cells are characterized by a metabolic switch from glucose-facilitated oxidative phosphorylation to lactate-facilitated oxidative phosphorylation. Although PHD-2 was found in OXOPHOS cells. There is no clear explanation for the presence of NF-kappa B activity. The accumulation of the competitive inhibitor of 2-oxo-glutarate, pyruvate, in non-hypoxic tumour cells is well established. So, we conclude that PHD-2 is inactive in non-hypoxic tumour cells due to pyruvate-mediated competitive suppression of 2-oxo-glutarate. This results in canonical activation of NF-κB. In non-hypoxic tumour cells, 2-oxoglutarate serves as a limiting factor, rendering PHD-2 inactive. However, FIH prevents HIF-1α from engaging in its transcriptional actions. Using the existing scientific literature, we conclude in this study that NF-κB is the major regulator of tumour cell growth and proliferation via pyruvate-mediated competitive inhibition of PHD-2.

Enhancers regulate 3' end processing activity to control expression of alternative 3'UTR isoforms

Multi-UTR genes are widely transcribed and express their alternative 3'UTR isoforms in a cell type-specific manner. As transcriptional enhancers regulate mRNA expression, we investigated if they also regulate 3'UTR isoform expression. Endogenous enhancer deletion of the multi-UTR gene PTEN did not impair transcript production but prevented 3'UTR isoform switching which was recapitulated by silencing of an enhancer-bound transcription factor. In reporter assays, enhancers increase transcript production when paired with single-UTR gene promoters. However, when combined with multi-UTR gene promoters, they change 3'UTR isoform expression by increasing 3' end processing activity of polyadenylation sites. Processing activity of polyadenylation sites is affected by transcription factors, including NF-κB and MYC, transcription elongation factors, chromatin remodelers, and histone acetyltransferases. As endogenous cell type-specific enhancers are associated with genes that increase their short 3'UTRs in a cell type-specific manner, our data suggest that transcriptional enhancers integrate cellular signals to regulate cell type-and condition-specific 3'UTR isoform expression.

Impact of quorum sensing signaling molecules in gram-negative bacteria on host cells: current understanding and future perspectives

Quorum sensing is a molecular signaling-based communication mechanism in prokaryotes. In the basic mode, signaling molecules released by certain bacteria are sensed by intracellular receptors or membrane-bound receptors of other members in the community, leading to the collective isogenic signaling molecule synthesis and synchronized activities. This regulation is important for the symbiosis of the bacterium with the host, as well as virulence and biofilm formation. Notably, quorum sensing signaling molecules are not only able to control microbial community behavior but can likewise regulate the physiological status of host cells. Here, we provide a comprehensive review of the importance of quorum sensing signaling molecules in gram-negative bacteria in regulating host cell function and gut health, and suggest possible opportunities for application in combating human and animal diseases by blocking the pathways through which quorum sensing signaling molecules exert their functions.

Identification of distinct slow mode of reversible adaptation of pancreatic ductal adenocarcinoma to the prolonged acidic pH microenvironment

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is the most common pancreatic neoplasm with high metastatic potential and poor clinical outcome. Like other solid tumors, PDAC in the early stages is often asymptomatic, and grows very slowly under a distinct acidic pHe (extracellular pH) microenvironment. However, most previous studies have only reported the fate of cancerous cells upon cursory exposure to acidic pHe conditions. Little is known about how solid tumors-such as the lethal PDAC originating within the pancreatic duct-acinar system that secretes alkaline fluids-evolve to withstand and adapt to the prolonged acidotic microenvironmental stress.

METHODS

Representative PDAC cells were exposed to various biologically relevant periods of extracellular acidity. The time effects of acidic pHe stress were determined with respect to tumor cell proliferation, phenotypic regulation, autophagic control, metabolic plasticity, mitochondrial network dynamics, and metastatic potentials.

RESULTS

Unlike previous short-term analyses, we found that the acidosis-mediated autophagy occurred mainly as an early stress response but not for later adaptation to microenvironmental acidification. Rather, PDAC cells use a distinct and lengthy process of reversible adaptive plasticity centered on the early fast and later slow mitochondrial network dynamics and metabolic adjustment. This regulates their acute responses and chronic adaptations to the acidic pHe microenvironment. A more malignant state with increased migratory and invasive potentials in long-term acidosis-adapted PDAC cells was obtained with key regulatory molecules being closely related to overall patient survival. Finally, the identification of 34 acidic pHe-related genes could be potential targets for the development of diagnosis and treatment against PDAC.

CONCLUSIONS

Our study offers a novel mechanism of early rapid response and late reversible adaptation of PDAC cells to the stress of extracellular acidosis. The presence of this distinctive yet slow mode of machinery fills an important knowledge gap in how solid tumor cells sense, respond, reprogram, and ultimately adapt to the persistent microenvironmental acidification.

Piperlongumine, a piper alkaloid, enhances the efficacy of doxorubicin in breast cancer: involvement of glucose import, ROS, NF-κB and lncRNAs

Piperlongumine (PL, piplartine) is an alkaloid derived from the Piper longum L. (long pepper) roots. Originally discovered in 1961, the biological activities of this molecule against some cancer types was reported during the last decade. Whether PL can synergize with doxorubicin and the underlying mechanism in breast cancer remains elusive. Herein, we report the activities of PL in numerous breast cancer cell lines. PL reduced the migration and colony formation by cancer cells. An enhancement in the sub-G1 population, reduction in the mitochondrial membrane potential, chromatin condensation, DNA laddering and suppression in the cell survival proteins was observed by the alkaloid. Further, PL induced ROS generation in breast cancer cells. While TNF-α induced p65 nuclear translocation, PL suppressed the translocation in cancer cells. The expression of lncRNAs such as MEG3, GAS5 and H19 were also modulated by the alkaloid. The molecular docking studies revealed that PL can interact with both p65 and p50 subunits. PL reduced the glucose import and altered the pH of the medium towards the alkaline side. PL also suppressed the expression of glucose and lactate transporter in breast cancer cells. In tumor bearing mouse model, PL was found to synergize with doxorubicin and reduced the size, volume and weight of the tumor. Overall, the effects of doxorubicin in cancer cells are enhanced by PL. The modulation of glucose import, NF-κB activation and lncRNAs expression may have contributory role for the activities of PL in breast cancer.

The role of tumor acidification in aggressiveness, cell dissemination and treatment resistance of oral squamous cell carcinoma

AIMS

To investigate the role of tumor acidification in cell behavior, migration, and treatment resistance of oral squamous cell carcinoma (OSCC).

MAIN METHODS

The SCC4 and SCC25 cell lines were exposed to acidified (pH 6.8) cell culture medium for 7 days. Alternatively, a long-term acidosis was induced for 21 days. In addition, to mimic dynamic pH fluctuation of the tumor microenvironment, cells were reconditioned to neutral pH after experimental acidosis. This study assessed cell proliferation and viability by sulforhodamine B and flow cytometry. Individual and collective cell migration was analyzed by wound healing, time lapse, and transwell assays. Modifications of cell phenotype, EMT induction and stemness potential were investigated by qRT-PCR, western blot, and immunofluorescence. Finally, resistance to chemo- and radiotherapy of OSCC when exposed to acidified environmental conditions (pH 6.8) was determined.

KEY FINDINGS

The exposure to an acidic microenvironment caused an initial reduction of OSCC cells viability, followed by an adaptation process. Acidic adapted cells acquired a mesenchymal-like phenotype along with increased migration and motility indexes. Moreover, tumoral extracellular acidity was capable to induce cellular stemness and to increase chemo- and radioresistance of oral cancer cells.

SIGNIFICANCE

In summary, the results showed that the acidic microenvironment leads to a more aggressive and treatment resistant OSCC cell population.

Dietary Acid Load, Serum Polychlorinated Biphenyl Levels, and Mortality Following Breast Cancer in the Long Island Breast Cancer Study Project

Dietary acid load (DAL) may be associated with all-cause mortality (ACM) and breast cancer-specific mortality (BCM), and these associations may be modified by serum polychlorinated biphenyl (PCB) levels. Participants included 519 women diagnosed with first primary in situ or invasive breast cancer in 1996/1997 with available lipid-corrected PCB data. After a median of 17 years, there were 217 deaths (73 BCM). Potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores calculated from a baseline food frequency questionnaire estimated DAL. Cox regression estimated covariate-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between PRAL and NEAP with mortality. We evaluated effect measure modification by total serum PCB levels (>median vs. ≤median). PRAL quartile 4 versus quartile 1 was associated with an ACM HR of 1.31 (95%CI = 0.90-1.92). In the upper median of PCBs, ACM HRs were 1.43 (95%CI = 0.96-2.11) and 1.40 (95%CI = 0.94-2.07) for PRAL and NEAP upper medians, respectively. In the lower median of PCBs, the upper median of NEAP was inversely associated with BCM (HR = 0.40, 95%CI = 0.19-0.85). DAL may be associated with increased risk of all-cause mortality following breast cancer among women with high total serum PCB levels, but inversely associated with breast cancer mortality among women with low PCB levels.

Lactobacillus casei ATCC 393 and it's metabolites alleviate dextran sulphate sodium-induced ulcerative colitis in mice through the NLRP3-(Caspase-1)/IL-1β pathway

Inflammatory bowel disease (IBD) represents a broad group of intestinal disorders, including ulcerative colitis (UC) and Crohn's disease (CD). Probiotics are increasingly being recognized as a means of treatment for people suffering from IBD. Our previous studies demonstrated that Lactobacillus casei ATCC 393 (L. casei ATCC 393) effectively alleviated enterotoxigenic Escherichia coli K88-induced intestinal barrier dysfunction. This study was conducted to investigate the protective effects of L. casei ATCC 393 and its metabolites on dextran sulfate sodium (DSS)-induced UC in C57BL/6 mice and the potential mechanism of these effects. The results showed that oral administration of L. casei ATCC 393 and its metabolites both effectively reversed the DSS-induced weight loss, and the reduction in the disease activity index (DAI), colon length, and villus height of colon tissue in mice. Compared to the DSS-induced model group, L. casei ATCC 393 and its metabolites significantly inhibited the infiltration of immune cells into the intestinal mucosa, decreased the production of pro-inflammatory factors, and increased the expression of anti-inflammatory factors in the serum and colon tissue, increased the expression levels of occludin, ZO-1, and claudin-1, and reduced the expression of nucleotide binding oligomeric domain-like receptor protein 3 (NLRP3), cysteine proteinase-1 (Caspase-1), IL-1β, and IL-18. In addition, L. casei ATCC 393 and its metabolites effectively improved DSS-induced gut microbiota dysbiosis. These results suggested that L. casei ATCC 393 and its metabolites alleviated the DSS-induced ulcerative inflammatory response in C57BL/6 mice through the NLRP3-(Caspase-1)/IL-1β signaling pathway.

The metabolism of cancer cells during metastasis

Metastasis formation is the major cause of death in most patients with cancer. Despite extensive research, targeting metastatic seeding and colonization is still an unresolved challenge. Only recently, attention has been drawn to the fact that metastasizing cancer cells selectively and dynamically adapt their metabolism at every step during the metastatic cascade. Moreover, many metastases display different metabolic traits compared with the tumours from which they originate, enabling survival and growth in the new environment. Consequently, the stage-dependent metabolic traits may provide therapeutic windows for preventing or reducing metastasis, and targeting the new metabolic traits arising in established metastases may allow their eradication.

Phosphoenolpyruvate Carboxykinase (PCK) in the Brain Gluconeogenic Pathway Contributes to Oxidative and Lactic Injury After Stroke

To demonstrate the role of the rate-limiting and ATP-dependent gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PCK) in oxidative and lactic stress and the effect of phenothiazine on PCK after stroke, a total of 168 adult male Sprague Dawley rats (3 months old, 280-300 g) underwent 2-h intraluminal middle cerebral artery occlusion (MCAO) and reperfusion for 6, 24, 48 h, or 7 days. Phenothiazine (chlorpromazine and promethazine (C+P)) (8 mg/kg) and 3-mercaptopicolinic acid (3-MPA, a PCK inhibitor, 100 μM) were administered at reperfusion onset. The effects of phosphoenolpyruvate, 3-MPA, or PCK knockdown were studied in neuronal cultures subjected to oxygen/glucose deprivation. Reactive oxygen species, lactate, phosphoenolpyruvate (PEP; a gluconeogenic product), mRNA, and protein of total PCK, PCK-1, and PCK-2 increased after MCAO and oxygen-glucose deprivation (OGD). Oxaloacetate (a gluconeogenic substrate) decreased, while PEP and glucose were increased, suggesting reactive gluconeogenesis. These changes were attenuated by phenothiazine, 3-MPA, or PCK shRNA. PCK-1 and -2 existed primarily in neurons, while the effects of ischemic stroke on the PCK expression were seen predominately in astrocytes. Thus, phenothiazine reduced infarction and oxidative/lactic stress by inhibiting PCKs, leading to functional recovery.

Differential metabolic responses in breast cancer cell lines to acidosis and lactic acidosis revealed by stable isotope assisted metabolomics

Extracellular acidosis is considered as a hallmark of most human tumors, which plays an important role in promoting tumor malignant and aggressive phenotype in tumorigenesis. Acidosis and lactic acidosis can induce different responses in tumors. Previous studies have associated the response to lactic acidosis of tumors with good survival outcomes. In this study, we investigated the metabolomic changes in triple negative and luminal subtype breast cancer cell lines in response to acidosis and lactic acidosis. Our results showed that acidosis results in the reduction of cell viability and glycolysis in breast cancer cells, which is reversely correlated with the malignancy of cell lines. Under lactic acidosis, this reduction is reversed slightly. Untargeted metabolomic profiling revealed that glutaminolysis and fatty acid synthesis in cancer cells under acidosis are increased, while TCA cycle and glycolysis are decreased. Under lactic acidosis, the pentose phosphate pathway and acetate release are increased in MDA-MB-231 cells. The current results uncovered the different metabolic responses of breast cancer cells to acidosis and lactic acidosis, demonstrating the power of combined untargeted and stable isotope assisted metabolomics in comprehensive metabolomic analysis.

Overexpression of acid-sensing ion channel 1a (ASIC1a) promotes breast cancer cell proliferation, migration and invasion

Background

The microenvironment of various tumor tissues is acidic. Acid-sensing ion channels (ASICs) are a class of ligand-gated ion channels which are sensitive to extracellular protons and are often highly expressed in tumor tissues. Breast cancer, whose extracellular microenvironment is thought to be acidic, is the most common cancer type among females in the world.

Methods

Thirty breast cancer tissues and adjacent normal tissues of patients were collected from 2009 to 2015 at the Xinhua hospital affiliated to Shanghai Jiao Tong University School of Medicine. The expression of acid-sensing ion channel 1a (ASIC1a), a subtype of ASICs family, was detected by immunohistochemistry in breast cancer tissues, and the effect of ASIC1a on the physiological activity of tumor cells was analyzed in vitro and in vivo experiments.

Results

In this study, it was found that ASIC1a is highly expressed in the tissues of breast cancer patients. In vitro experiments revealed that down-regulation of ASIC1a by its antagonist PcTx-1 or ASIC1a siRNA could significantly weaken the migration, proliferation and invasion of tumor cells. In vivo studies, down-regulation or inhibition of the ASIC1a could inhibit breast tumor growth.

Conclusions

The high expression of ASIC1a might be related to the enhanced biological activity of breast cancer cells. Whether ASIC1a is a potential therapeutic target for some types of breast cancer deserves further study.

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

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

Epoxyazadiradione exhibit activities in head and neck squamous cell carcinoma by targeting multiple pathways

The head and neck squamous cell carcinoma (HNSCC) constitute about 90% of all head and neck cancers. HNSCC falls in the top 10 cancers in men globally. Epoxyazadiradione (EPA) and Azadiradione (AZA) are the limonoids derived from the medicinal plant Azadirachta indica (popularly known as Neem). Whether or not the limonoids exhibit activities against HNSCC and the associated mechanism remains elusive. Herein, we demonstrate that EPA exhibits stronger activity in HNSCC in comparison to AZA. The limonoids obeyed the Lipinski's rule of 5. EPA exhibited activities in a variety of HNSCC lines like suppression of the proliferation and the induction of apoptosis. The limonoid suppressed the level of proteins associated with anti-apoptosis (survivin, Bcl-2, Bcl-xL), proliferation (cyclin D1), and invasion (MMP-9). Further, the expression of proapoptotic Bax and caspase-9 cleavage was induced by the limonoid. Exposure of EPA induced reactive oxygen species (ROS) generation in the FaDu cells. N-acetyl-L-cysteine (ROS scavenger) abrogated the down-regulation of tumorigenic proteins caused by EPA exposure. EPA induced NOX-5 while suppressing the expression of programmed death-ligand 1 (PD-L1). Further, hydrogen peroxide induced NF-κB-p65 nuclear translocation and EPA inhibited the translocation. Finally, EPA modulated the expression of lncRNAs in HNSCC lines. Overall, these results have shown that EPA exhibit activities against HNSCC by targeting multiple cancer related signalling molecules. Currently, we are evaluating the efficacy of this molecule in mice models.

Recombinant human lactoferrin attenuates the progression of hepatosteatosis and hepatocellular death by regulating iron and lipid homeostasis in ob/ob mice

Lactoferrin (Lf), an iron-binding glycoprotein, has been shown to possess antioxidant and anti-inflammatory properties and exert modulatory effects on lipid homeostasis and non-alcoholic fatty liver disease (NAFLD), but our understanding of its regulatory mechanisms is limited and inconsistent. We used leptin-deficient (ob/ob) mice as the rodent model of NAFLD, and administered recombinant human Lf (4 mg per kg body weight) or control vehicle by intraperitoneal injection to evaluate the hepatoprotective effects of Lf. After 40 days of treatment with Lf, insulin sensitivity and hepatic steatosis in ob/ob mice were significantly improved with the down-regulation of sterol regulatory element binding protein-2 (SREBP2), indicating an improvement in hepatic lipid metabolism and function. We further explored the mechanism, and found that Lf may increase the hepatocellular iron output by targeting the hepcidin-ferroportin (FPn) axis, and then maintains the liver oxidative balance through a nonenzymatic antioxidant system, ultimately suppressing the death of hepatocytes. In addition, the cytoprotective role of Lf may be associated with the inhibition of endoplasmic reticulum (ER) stress and inflammation, promotion of autophagy of damaged hepatocytes and induction of up-regulation of hypoxia inducible factor-1α/vascular endothelial growth factor (HIF-lα/VEGF) to facilitate liver function recovery. These findings suggest that recombinant human Lf might be a potential therapeutic agent for mitigating or delaying the pathological process of NAFLD.

CAIX-Mediated Control of LIN28/let-7 Axis Contributes to Metabolic Adaptation of Breast Cancer Cells to Hypoxia

Solid tumors, including breast cancer, are characterized by the hypoxic microenvironment, extracellular acidosis, and chemoresistance. Hypoxia marker, carbonic anhydrase IX (CAIX), is a pH regulator providing a selective survival advantage to cancer cells through intracellular neutralization while facilitating tumor invasion by extracellular acidification. The expression of CAIX in breast cancer patients is associated with poor prognosis and metastases. Importantly, CAIX-positive hypoxic tumor regions are enriched in cancer stem cells (CSCs). Here we investigated the biological effects of CA9-silencing in breast cancer cell lines. We found that CAIX-downregulation in hypoxia led to increased levels of let-7 (lethal-7) family members. Simultaneously with the increase of let-7 miRNAs in CAIX-suppressed cells, LIN28 protein levels decreased, along with downstream metabolic pathways: pyruvate dehydrogenase kinase 1 (PDK1) and phosphorylation of its substrate, pyruvate dehydrogenase (PDH) at Ser-232, causing attenuation of glycolysis. In addition to perturbed glycolysis, CAIX-knockouts, in correlation with decreased LIN28 (as CSC reprogramming factor), also exhibit reduction of the further CSC-associated markers NANOG (Homeobox protein NANOG) and ALDH1 (Aldehyde dehydrogenase isoform 1). Oppositely, overexpression of CAIX leads to the enhancement of LIN28, ALDH1, and NANOG. In conclusion, CAIX-driven regulation of the LIN28/let-7 axis augments glycolytic metabolism and enhances stem cell markers expression during CAIX-mediated adaptation to hypoxia and acidosis in carcinogenesis.

Extracellular Acidosis Promotes Metastatic Potency via Decrease of the BMAL1 Circadian Clock Gene in Breast Cancer

Circadian oscillation is an essential process that influences many physiological and biological mechanisms and a decrease of circadian genes is associated with many diseases such as cancer. Despite many efforts to identify the detailed mechanism for decreasing circadian genes and recovering reduced circadian genes in cancer, it is still largely unknown. We found that BMAL1 was reduced in tumor hypoxia-induced acidosis, and recovered by selectively targeting acidic pH in breast cancer cell lines. Surprisingly, BMAL1 was reduced by decrease of protein stability as well as inhibition of transcription under acidosis. In addition, melatonin significantly prevented acidosis-mediated decrease of BMAL1 by inhibiting lactate dehydrogenase-A during hypoxia. Remarkably, acidosis-mediated metastasis was significantly alleviated by BMAL1 overexpression in breast cancer cells. We therefore suggest that tumor hypoxia-induced acidosis promotes metastatic potency by decreasing BMAL1, and that tumor acidosis could be a target for preventing breast cancer metastasis by sustaining BMAL1.

Acidosis promotes tumorigenesis by activating AKT/NF-κB signaling

The microenvironment of solid tumors is often acidic due to poor vascular perfusion, regional hypoxia, and increased glycolytic activity of tumor cells. Although acidosis is harmful to most types of cells, tumor cells seem well adapted to such harsh conditions. Moreover, overwhelming evidence indicates that tumor cells are more invasive and more aggressive in acidic conditions by a cascade of cell signaling and upregulation of oncogenic gene expression. Therefore, how extracellular acidic signals are transduced to the cytoplasm and then into the nucleus is an interesting topic to many cancer researchers. In this review, we update on the recent advances in acidosis-induced tumorigenesis through the acid-sensing ion channels (ASICs) and activation of cell signaling.

Pro- and antitumor effects of mitochondrial reactive oxygen species

In cancer, mitochondrial functions are commonly altered. Directly involved in metabolic reprogramming, mitochondrial plasticity confers to cancer cells a high degree of adaptability to a wide range of stresses and to the harsh tumor microenvironment. Lack of nutrients or oxygen caused by altered perfusion, metabolic needs of proliferating cells, co-option of the microenvironment, control of the immune system, cell migration and metastasis, and evasion of exogenous stress (e.g., chemotherapy) are all, at least in part, influenced by mitochondria. Mitochondria are undoubtedly one of the key contributors to cancer development and progression. Understanding their protumoral (dys)functions may pave the way to therapeutic strategies capable of turning them into innocent entities. Here, we will focus on the production and detoxification of mitochondrial reactive oxygen species (mtROS), on their impact on tumorigenesis (genetic, prosurvival, and microenvironmental effects and their involvement in autophagy), and on tumor metastasis. We will also summarize the latest therapeutic approaches involving mtROS.

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

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

NEK7 interacts with NLRP3 to modulate the pyroptosis in inflammatory bowel disease via NF-κB signaling

Inflammatory bowel disease (IBD) is one of the most common diseases in the gastrointestinal tract related to aberrant inflammation. Pyroptosis, which is characterized by inflammasome formation, the activation of caspase-1, and the separation of the N- and C-terminals of GSDMD, might be related to IBD pathogenesis. NEK7 is an important component of the NLRP3 inflammasome in macrophages. We attempted to investigate the mechanism of NEK7 interacting with NLRP3 to modulate the pyroptosis in IBD. NEK7 mRNA and protein expression and pyroptosis-associated factors, including Caspase-1 (p45, p20), NLRP3, and GSDMD, were upregulated in IBD tissues. NEK7 knockdown abolish ATP + LPS-induced pyroptosis in vitro and improved DSS-induced chronic colitis in vivo. NEK7 interacted with NLRP3, as revealed by Co-IP and GST pull-down assays, to exert its effects. Moreover, short-term LPS treatment alone induced no significant changes in NEK7 protein level. TLR4/NF-κB signaling in MODE-K cells could be activated by LPS treatment. LPS-induced NEK7 upregulation could be significantly reversed by JSH-23, an inhibitor of p65. Furthermore, LUC and ChIP assays revealed that RELA might activate the transcription of NEK7 via targeting its promoter region. LPS-induced TLR4/NF-κB activation causes an increase in NEK7 expression by RELA binding NEK7 promoter region. In conclusion, NEK7 interacts with NLRP3 to modulate NLRP3 inflammasome activation, therefore modulating the pyroptosis in MODE-K cells and DSS-induced chronic colitis in mice. We provide a novel mechanism of NEK7-NLRP3 interaction affecting IBD via pyroptosis.

Isodeoxyelephantopin, a Sesquiterpene Lactone Induces ROS Generation, Suppresses NF-κB Activation, Modulates LncRNA Expression and Exhibit Activities Against Breast Cancer

The sesquiterpene lactones, Isodeoxyelephantopin (IDET) and Deoxyelephantopin (DET) are known to exhibit activities against some cancer types. The activities of these lactones against breast cancer and the molecular bases is not known. We examined the efficacy of lactones in breast cancer preclinical model. Although both lactones exhibited drug like properties, IDET was relatively effective in comparison to DET. IDET suppressed the proliferation of both invasive and non-invasive breast cancer cell lines. IDET also suppressed the colony formation and migration of breast cancer cells. The assays for Acridine Orange (AO)/Propidium Iodide (PI) staining, cell cycle distribution, phosphatidylserine externalization and DNA laddering suggested the apoptosis inducing potential of IDET. The treatment with IDET also induced an accumulation of cells in the sub-G1 and G2/M phases. The exposure of breast cancer cells to the lactone was associated with a depolarization in mitochondrial membrane potential, and cleavage of caspase and PARP. The lactone induced reactive oxygen species (ROS) generation in breast cancer cells. Further, the use of N-acetyl cysteine (NAC) suppressed IDET induced ROS generation and apoptosis. The NF-κB-p65 nuclear translocation induced by okadaic acid (OA) was suppressed by the sesquiterpene. IDET also suppressed the expression of NF-κB regulated tumorigenic proteins, and induced the expression of proapoptotic gene (Bax) in cancer cells. While the expression of oncogenic lncRNAs was suppressed, the tumor suppressor lncRNAs were induced by the sesquiterpene. Collectively, the modulation of multiple cell signaling molecules by IDET may contribute to its activities in breast cancer cells.

Acidic pH derived from cancer cells as a double-edged knife modulates wound healing through DNA repair genes and autophagy

Wound healing is a sequester program that involves diverse cell signalling cascades. Notwithstanding, complete signal transduction pathways underpinning acidic milieu derived from cancer cells is not clear, yet. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, fluorescein diacetate/propidium iodide staining, and cell cycle flow cytometry revealed that acidic media decreased cell viability and cell number along with enhanced dead cells and S-phase arrest in normal fibroblasts. Notably, the trends of intracellular reactive oxygen species production and lactate dehydrogenase release significantly increased with time. It seems the downregulation of Klf4 is in part due to acidosis-induced DNA damage. It promoted cells towards S-phase arrest and diminished cell proliferation. Klf4 downregulation had a direct correlation with the P53 level while acidic microenvironment promotes cells towards cell death mechanisms including apoptosis and autophagy. Noteworthily, the unchanged levels of Rb and Mlh1 indicated in those genes had no dominant role in the repairing of DNA damage in fibroblasts treated with the acidic microenvironment. Therefore, cells owing to not entering to mitosis and accumulation of DNA damage were undergone cell death to preserve cell homeostasis. Since acidic media decreased the level of tumour suppressor and DNA repair genes and altered the normal survival pathways in fibroblasts, caution should be exercised to not lead to cancer rather than wound healing.

The critical role of calcineurin/NFAT (C/N) pathways and effective antitumor prospect for colorectal cancers

Transcription factors (TFs) like a nuclear factor of activated T-cells (NFAT) and its controller calcineurin are highly expressed in primary intestinal epithelial cells (IECs) due to delamination, damage by tumor-associated flora and selective activation in the intestinal tract tumor are crucial in the progression and growth of colorectal cancer (CRC). This study sought to summarize the current findings concerning the dysregulated calcineurin/NFAT (C/N) signaling involved in CRC initiation and progression. These signalings include proliferation, T-cell functions, and glycolysis with high lactate production that remodels the acidosis, which genes in tumor cells provide an evolutionary advantage, or even increased their attack phenotype. Moreover, the relationship between C/N and gut microbiome in CRC, especially role of NFAT and toll-like receptor signaling in regulating intestinal microbiota are also discussed. Furthermore, this review will discuss the proteins and genes relating to C/N induced acidosis in CRC, which includes ASIC2 regulated C/N1 and TFs associated with the glycolytic by-product that affect T-cell functions and CRC cell growth. It is revealed that calcineurin or NFAT targeting to antitumor, selective calcineurin inhibition or targets in NFAT signaling may be useful for clinical treatment of CRC. This can further aid in the identification of specific targets via cancer patient-personalized approach. Future studies should be focused on targeting to C/N or TLR signaling by the combination of therapeutic agents to regulate T-cell functions and gut microbiome for activating potent anticancer property with the prospect of potentiating the antitumor therapy for CRC.

LINC00346 promotes pancreatic cancer progression through the CTCF-mediated Myc transcription

Although multiple factors are known to contribute to pancreatic ductal adenocarcinoma (PDAC) progression, the role of long non-coding RNAs (lncRNAs) in PDAC remains largely unknown. In this study, we present data that long intergenic non-coding RNA 346 (LINC00346) functions as a promoting factor for PDAC development. We first show that LINC00346 is highly expressed in pancreatic tumor specimens as compared to normal pancreatic tissue based on interrogation of The Cancer Genome Atlas (TCGA) pancreatic adenocarcinoma dataset. Of significance, this upregulation of LINC00346 is associated with overall survival (OS) and disease-free survival (DFS), respectively. We further show that knockout (KO) of LINC00346 impairs pancreatic cancer cell proliferation, tumorigenesis, migration, and invasion ability. Importantly, these phenotypes can be restored by LINC00346 re-expression in KO cells (i.e., rescue experiment). RNA precipitation assays combined with mass spectrometry analysis indicate that LINC00346 interacts with CCCTC-binding factor (CTCF), a known transcriptional repressor of c-Myc. This interaction between LINC00346 and CTCF prevents the binding of CTCF to c-Myc promoter, relieving the CTCF-mediated repression of c-Myc. Thus, LINC00346 functions as a positive transcriptional regulator of c-Myc. Together, these results suggest that LINC00346 contributes to PDAC pathogenesis by activating c-Myc, and as such, LINC00346 may serve as a potential biomarker and therapeutic target for PDAC.

Inhibition of ubiquitin specific protease 17 restrains prostate cancer proliferation by regulation of epithelial-to-mesenchymal transition (EMT) via ROS production

Prostate cancer is one of the most frequently diagnosed neoplasms among men in the world. However, molecular mechanisms underlying the progression of prostate cancer are still unclear. In the study, we investigated the effects of ubiquitin specific protease 17 (USP17) on prostate cancer growth. The results indicated that USP17 expression was markedly increased in prostate cancer tissues and cell lines. Repressing USP17 expression significantly reduced the proliferation, migration and invasion of prostate cancer cells using cell counting kit-8 (CCK-8), colony formation and transwell assays. In addition, apoptosis was significantly induced by USP17 knockdown via increasing the expression of cleaved Caspase-9/-3 and poly (ADP)-ribose polymerase (PARP), as well as Cyto-c. Further, USP17 silence evidently promoted reactive oxygen species (ROS) production in prostate cancer cells. Nuclear nuclear factor-κB (NF-κB)/p65 expression and total NF-κB/p65 phosphorylation were markedly down-regulated by USP17 repression. Intriguingly, blocking ROS generation using its scavenger of N-acetyl-l-cysteine (NAC) significantly abrogated USP17 knockdown-induced apoptosis and -inhibited NF-κB/p65 signaling in vitro. Our data also showed that USP17 silence impaired tumor growth in the subcutaneous mouse model in vivo. Taken together, our results suggested that USP17 decrease might exert anti-tumor activities against prostate cancer growth by inducing apoptosis and suppressing NF-κB/p65 signaling via the promotion of ROS. Thus, USP17 could be served as a promising candidate to develop effective therapeutic strategy against prostate cancer progression.

Antiproliferative activity and p53 upregulation effects of chalcones on human breast cancer cells

Chalcones are valuable structures for drug discovery due to their broad bioactivity spectrum. In this study, we evaluated 20 synthetic chalcones against estrogen-receptor-positive breast cancer cells (MCF-7 line) and triple-negative breast cancer (TNBC) cells (MDA-MB-231 line). Antiproliferative screening by MTT assay resulted in two most active compounds: 2-fluoro-4’-aminochalcone (11) and 3-pyridyl-4’-aminochalcone (17). Their IC₅₀ values ranged from 13.2 to 34.7 µM against both cell lines. Selected chalcones are weak basic compounds and maintained their antiproliferative activity under acidosis conditions (pH 6.7), indicating their resistance to ion-trapping effect. The mode of breast cancer cells death was investigated and chalcones 11 and 17 were able to induce apoptosis rather than necrosis in both lines. Antiproliferative target investigations with MCF-7 cells suggested 11 and 17 upregulated p53 protein expression and did not affect Sp1 protein expression. Future studies on chalcones 11 and 17 can define their in vivo therapeutic potential.

Pre-treatment serum bicarbonate predicts for primary tumor control after stereotactic body radiation therapy in patients with localized non-small cell lung cancer

BACKGROUND

Tumor aggressiveness and hypoxia are linked to acidosis in the tumor microenvironment (TME). We hypothesized that low pre-treatment serum bicarbonate, potentially correlating with an acidic and hypoxic TME, predicts for poor outcomes after stereotactic body radiation therapy (SBRT) for non-small cell lung cancer (NSCLC).

METHODS

We included patients with localized NSCLC treated to a biologically effective dose (BED) ≥ 100 Gy, with available pre-treatment bicarbonate values within 3 months of treatment. We used receiver operating characteristic analysis to determine the bicarbonate concentration optimally predicting for primary tumor recurrence, and evaluated its association with recurrence and survival. We validated our findings in an independent cohort of patients from three collaborating institutions.

RESULTS

A total of 110 patients and 114 tumors were included in the training cohort, with median follow-up of 15.0 months. Bicarbonate < 26 mEq/L was associated with primary tumor recurrence on univariate (HR = 5.92; 95% CI 1.69-24.88; p = 0.005) and multivariate analysis (HR = 5.48; 95% CI 1.37-25.19; p = 0.020). The validation cohort consisted of 195 patients and 208 tumors with median follow-up of 27.5 months. In the validation cohort, bicarbonate < 26 mEq/L was again associated with primary tumor recurrence on univariate (HR = 3.38; 95% CI 1.27-9.37; p = 0.015) and multivariate analysis (HR = 3.33; 1.18-10.07; p = 0.023).

CONCLUSIONS

Pre-treatment bicarbonate predicts for primary tumor control in NSCLC treated with SBRT and may be useful for risk stratification. These findings should be confirmed prospectively.

Acid microenvironment promotes cell survival of human bone sarcoma through the activation of cIAP proteins and NF-κB pathway

Extracellular acidification is a very common cause of stress in tumor microenvironment and of Darwinian pressure. In acid areas of the tumor, most cancer cells are-albeit slowly proliferating-more resistant to cell death than those in well-perfused regions. Tumor acidosis can directly regulate the expression of pro-survival proteins since a low extracellular pH activates the caspase-dependent cell death machinery. This mechanism has never been explored in bone sarcomas. We cultured osteosarcoma and Ewing sarcoma cells under low pH (pH 6.5), and we performed deep-sequencing and protein analysis. Both in in vitro and in vivo models, acidification activity enhanced tumor cells survival. However, we did not observe any change in ERK1 phosphorylation. On the contrary, both at the mRNA and protein level, we found a significant induction of TRAF adaptor proteins and of cIAP proteins (BIRC2 and/or BIRC3). As a consequence, the downstream nuclear transcription factor kappa B (NF-κB) survival pathway was increased. Furthermore, the treatment with the cIAP inhibitor LCL161 reverted the protection from apoptosis under low pH. In vitro results were confirmed both in Ewing sarcoma xenograft and in osteosarcoma patients, since the analysis of tumor tissues demonstrated that the levels of expression of TRAF1 or NF-κB1 significantly correlate with the level of expression of the vacuolar ATPase (V-ATPase), the most important proton pump in eukaryotes. Moreover, in the tissue sections of xenograft model, the nuclear translocation of RelB, a key subunit of the NF-κB transcriptional complex, localized in the tumor region that also corresponded to the acid microenvironment associated with the highest levels of expression of LAMP2 and V-ATPase, in the internal area of the tumor, as revealed by immunohistochemistry. Our data confirm that tumor acid microenvironment activates a stress-regulated switch to promote cell survival of bone sarcoma, and support the hypothesis that this mechanism is mediated by the recruitment of TRAF/cIAP complexes. Altogether, these results suggest that TRAF/cIAP can be considered as a target for anti-cancer therapies.

Key indexes and the emerging tool for tumor microenvironment editing

Many cancer management approaches including immunotherapies can not achieve desirable therapeutic efficacies if targeting tumors alone or could not effectively reach tumor cells. The concept of tumor microenvironment and its induced gene reprogramming have largely extended our current understandings on the determinants of tumor initiation/progression and fostered our hope in establishing first-line therapies targeting cancer microenvironment or adjuvant therapies enhancing the efficacies of existing oncotherapeutic modalities such as immunotherapies for efficient cancer management. This review identifies key indexes of tumor microenvironment, i.e., hypoxia, acidosis, hypo-nutrition and inflammation, which collectively determine the feature and the fate of adjacent tumor cells, and proposes cold atmospheric plasma, the fourth state of matter that is largely composed of various reactive oxygen and nitrogen species, as a promising tool for tumor microenvironment editing. We propose that cold atmospheric plasma represents an emerging onco-therapeutic strategy alone or complementing existing treatment approaches given its multi-modal nature through tumor microenvironment modulation.

Curcuma raktakanda Induces Apoptosis and Suppresses Migration in Cancer Cells: Role of Reactive Oxygen Species

Although over 100 species of Curcuma are reported, only Curcuma longa is extensively studied. Curcuma raktakanda, a poorly studied species, is most commonly distributed in the Kerala state of India. For the first time, we examined the efficacy of different fractions (acetone, hexane, and ethyl acetate) of C. raktakanda against glioma, cervical, and breast cancer cell lines. As determined by mitochondrial reductase activity assay, the viability of cancer cells was decreased in a concentration-dependent manner by the three fractions. The half maximal inhibitory concentration (IC-50) values after the treatment of C-6 glioma cells for 48 h was found to be 32.97 µg/mL (acetone extract), 40.63 µg/mL (hexane extract), and 51.65 µg/mL (ethyl acetate extract). Of the three fractions, the acetone fraction was more effective. The long-term colony formation of cancer cells was significantly suppressed by the acetone fraction. Analyses using DAPI (4',6-diamidino-2-phenylindole) staining, AO/PI (acridine orange/propidium iodide) staining, DNA laddering, and sub-G1 population revealed that the acetone extract induced apoptosis in glioma cells. The extract induced reactive oxygen species generation and suppressed the expression of cell survival proteins. The migration of cancer cells was also suppressed by the acetone extract. The gas chromatography-mass spectrometry (GC-MS) analysis indicated that tetracontane, dotriacontane, hexatriacontane, pentacosane, hexacosane, and eicosane are the major components in the acetone extract. Collectively, the extract from C. raktakanda exhibited anti-carcinogenic activities in cancer cells. We are exploring whether the phytoconstituents, individually, or collectively contribute to the anti-cancer activities of C. raktakanda.

A Novel Antibody-Toxin Conjugate to Treat Mantle Cell Lymphoma

Matriptase is a transmembrane serine protease, synthesized as an inactive single-chain zymogen on the endoplasmic reticulum and transported to the plasma membrane. Matriptase is activated in different epithelial and some B-cell malignancies and changes its conformation and activity is inhibited mainly by its endogenous inhibitor HAI-1. Activated matriptase plays a key role in tumor initiation as well as tumor progression, including invasiveness, and metastasis. To target the anti-mitotic toxin (monomethyl auristatin-E) to activated matriptase, a novel antibody to activated matriptase was conjugated with this toxin via a valine-citrulline-PABA linker. In a previous study, this antibody-toxin conjugate was found to be effective against triple negative breast cancer cell lines and xenografts, alone, or in combination with cisplatin (1). In this study, we examined the anti-tumor effect of the antibody toxin conjugate (ADC) against activated matriptase positive mantle cell lymphoma cell lines (JeKo-1, Maver, Mino, and Z138). This ADC was cytotoxic to these cell lines with IC₅₀s between 5 and 14 μg/mL. The ADC also showed a dose dependent anti-tumor effect on the JeKo-1 xenograft in mice without toxicity.

Reactive oxygen species and cancer: A complex interaction

Elevated levels of Reactive Oxygen Species (ROS), increased antioxidant ability and the maintenance of redox homeostasis can cumulatively contribute to tumor progression and metastasis. The sources and the role of ROS in a heterogeneous tumor microenvironment can vary at different stages of tumor: initiation, development, and progression, thus making it a complex subject. In this review, we have summarized the sources of ROS generation in cancer cells, its role in the tumor microenvironment, the possible functions of ROS and its important scavenger systems in tumor progression with special emphasis on solid tumors.

Nano-metal oxides induce antimicrobial resistance via radical-mediated mutagenesis

The widespread use of nanoparticles has triggered increasing concern and interest due to the adverse effects on global public health and environmental safety. Whether the presence of nano-metal oxides (NMOs) could facilitate the formation of new antimicrobial resistance genes (ARGs) via de novo mutation is largely unknown. Here, we proved that two widely used NMOs could significantly improve the mutation frequencies of CIP- and CHL-resistant E. coli isolates; however, the corresponding metal ions have weaker effects. Distinct concentration-dependent increases of 1.0-14.2 and 1.1-456.3 folds were observed in the resistance mutations after treatment with 0.16-100 mg/L nano-Al₂O₃ and 0.16-500 mg/L nano-ZnO, respectively, compared with those in the control. The resistant mutants showed resistance to multiple antibiotics and hereditary stability after sub-culturing for 5 days. We also explored the mechanism underlying the induction of antimicrobial resistance by NMOs. Whole-genome sequencing analysis showed that the mutated genes correlated with mono- and multidrug resistance, as well as undetected resistance to antibiotics. Furthermore, NMOs significantly promoted intracellular reactive oxygen species (ROS), which would lead to oxidative DNA damage and an error-prone SOS response, and consequently, mutation rates were enhanced. Our findings indicate that NMOs could accelerate the mutagenesis of multiple-antibiotic resistance and expanded the understanding of the mechanisms in nanoparticle-induced resistance, which may be significant for guiding the production and application of nanoparticles.

Activated matriptase as a target to treat breast cancer with a drug conjugate

The antitumor effects of a novel antibody drug conjugate (ADC) was tested against human solid tumor cell lines and against human triple negative breast cancer (TNBC) xenografts in immunosuppressed mice. The ADC targeting activated matriptase of tumor cells was synthesized by using the potent anti-tubulin toxin, monomethyl auristatin-E linked to the activated matriptase-specific monoclonal antibody (M69) via a lysosomal protease-cleavable dipeptide linker. This ADC was found to be cytotoxic against multiple activated matriptase-positive epithelial carcinoma cell lines in vitro and markedly inhibited growth of triple negative breast cancer xenografts and a primary human TNBC (PDX) in vivo. Overexpression of activated matriptase may be a biomarker for response to this ADC. The ADC had potent anti-tumor activity, while the unconjugated M69 antibody was ineffective in a mouse model study using MDA-MB-231 xenografts in mice. Treatment of a human TNBC (MDA-MB-231) showed potent anti-tumor effects in combination with cisplatin in mice. This ADC alone or in combination with cisplatin has the potential to improve the treatment outcomes of patients with TNBC as well as other tumors overexpressing activated matriptase.

The Double-Edged Sword Profile of Redox Signaling: Oxidative Events As Molecular Switches in the Balance between Cell Physiology and Cancer

The intracellular redox state in the cell depends on the balance between the level of reactive oxygen species (ROS) and the activity of defensive systems including antioxidant enzymes. This balance is a dynamic process that can change in relation to many factors and/or stimuli induced within the cell. ROS production is derived from physiological metabolic events. For instance, mitochondria represent the major ROS sources during oxidative phosphorylation, but other systems, such as NADPH oxidase or specific enzymes in certain metabolisms, may account for ROS production as well. Whereas high levels of ROS perturb the cell environment, causing oxidative damage to biological macromolecules, low levels of ROS can exert a functional role in the cell, influencing the activity of specific enzymes or modulating some intracellular signaling cascades. Of particular interest appears to be the role of ROS in tumor systems not only because ROS are known to be tumorigenic but also because tumor cells are able to modify their redox state, regulating ROS production to sustain tumor growth and proliferation. Overall, the scope of this review was to critically discuss the most recent findings pertaining to ROS physiological roles as well as to highlight the controversial involvement of ROS in tumor systems.

Involvement of HIF-1α-regulated miR-21, acting via the Akt/NF-κB pathway, in malignant transformation of HBE cells induced by cigarette smoke extract

Although the relationship between cigarette smoke and lung cancer has been widely studied, the molecular mechanism for cigarette smoke-induced lung cancer remains largely unclear. The present study investigated the roles of hypoxia-inducible factor (HIF)-1α and miR-21 in the malignant transformation of human bronchial epithelial (HBE) cells induced by cigarette smoke extract (CSE). In case of acute and chronic treatment of HBE cells, CSE increased the levels of HIF-1α, p-Akt, p-NF-κB, and miR-21 and decreased PTEN levels. The increased miR-21 levels induced by CSE were prevented by down-regulation of HIF-1α. Further, elevated miR-21 suppressed PTEN levels, which decreased the levels of p-Akt and p-NF-κB. However, those changes were attenuated in cells co-transfected with HIF-1α siRNA and an miR-21 mimic. Silencing of HIF-1α or NF-κB decreased colony formation and the invasion and migration capacities of CSE-transformed HBE cells; however, up-regulation of miR-21 reversed these effects. These results indicate that the oncogenic capacity of HIF-1α in regulation of miR-21-inhibited PTEN in a manner dependent on the Akt/NF-κB pathway, a process that is involved in the CSE-induced malignant transformation of HBE cells. Thus, the present research has established a new mechanism for cigarette smoke-induced lung carcinogenesis.

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.

Copper or/and arsenic induce oxidative stress-cascaded, nuclear factor kappa B-dependent inflammation and immune imbalance, trigging heat shock response in the kidney of chicken

Excessive amount of copper (Cu) and inorganic arsenic (iAs) coexists in drinking water in many regions, this is associated with high risk of nephropathy, defined as chronic structural and functional disorders of the kidney. However, the underlying mechanisms are not well understood. In this study, a total of 72 day-old Hy-line chickens were exposed to 300 mg/kg copper sulphate or/and 30 mg/kg arsenic trioxide for 12 weeks. Indicators of oxidative stress, inflammation and heat shock proteins (HSPs) production were analyzed in kidney. The results showed that, when the toxicant was administrated alone, there is an antagonism between redox homeostasis during the first 4 weeks, which follows a collapse of antioxidant system manifested by damaged biomembrane structure. What's worse, oxidative damage-cascaded histopathological lesions were accompanied by increases of proinflammatory mediators and an imbalance of "Th1/Th2 drift" (Th, helper T cell) regulated by nuclear factor kappa B (NF-κB). Simultaneously, intense heat shock response went with the organism. The above-mentioned renal lesions and indicators changes were time-dependent, more complex and deteriorated effects were observed in Cu/iAs combined groups compared with the others. This study supports Cu and iAs have a synergistic type on the nephro-toxicological process additively. In conclusion, oxidative stress and inflammatory induced by Cu or/and iAs are potential mechanisms in their nephrotoxicity, increased heat shock response may play a renoprotection function in tissues damage.

Tumour acidosis: from the passenger to the driver's seat

The high metabolic demand of cancer cells leads to an accumulation of H⁺ ions in the tumour microenvironment. The disorganized tumour vasculature prevents an efficient wash-out of H⁺ ions released into the extracellular medium but also favours the development of tumour hypoxic regions associated with a shift towards glycolytic metabolism. Under hypoxia, the final balance of glycolysis, including breakdown of generated ATP, is the production of lactate and a stoichiometric amount of H⁺ ions. Another major source of H⁺ ions results from hydration of CO₂ produced in the more oxidative tumour areas. All of these events occur at high rates in tumours to fulfil bioenergetic and biosynthetic needs. This Review summarizes the current understanding of how H⁺-generating metabolic processes segregate within tumours according to the distance from blood vessels and inversely how ambient acidosis influences tumour metabolism, reducing glycolysis while promoting mitochondrial activity. The Review also presents novel insights supporting the participation of acidosis in cancer progression via stimulation of autophagy and immunosuppression. Finally, recent advances in the different therapeutic modalities aiming to either block pH-regulatory systems or exploit acidosis will be discussed.