Hypoxic Conditions Research Articles

ST2 + T-Regulatory Cells in Renal Inflammation and Fibrosis after Ischemic Kidney Injury.

Inflammation is a major cause of kidney injury. The Interleukin (IL)-1 family cytokine IL-33 is released from damaged cells and modulates the immune response through its receptor ST2 expressed on many cell types, including regulatory T-cells (Tregs). While a proinflammatory role of IL-33 has been proposed, exogenous IL-33 expanded Tregs and suppressed renal inflammation. However, the contribution of endogenous IL-33/ST2 for the role of Tregs in the resolution of kidney injury has not been investigated. We used murine renal ischemia-reperfusion injury and kidney organoids to delineate the role of the ST2 and amphiregulin (AREG) specifically in Treg cells using targeted deletion. Bulk and single-cell RNA sequencing was performed on flow-sorted Tregs from spleen and CD4 T-cells from post-ischemic kidneys respectively. The protective role of ST2-sufficient Tregs was analyzed using a novel co-culture system of syngeneic kidney organoids and Treg cells under hypoxic conditions. Bulk RNA-sequencing of splenic and single-cell-RNA-sequencing of kidney T-cells showed that ST2+ Tregs are enriched for genes related to Treg proliferation and function. Genes for reparative factors such as AREG were also enriched in ST2+ Tregs. Treg-specific deletion of ST2 or AREG exacerbated kidney injury and fibrosis in the unilateral ischemia reperfusion injury model. In co-culture studies, WT but not ST2-deficient Tregs preserved the hypoxia-induced loss of kidney-organoid viability, which was restored by AREG supplementation. Our study identified the role of the IL-33/ST2 pathway in Tregs for resolution of kidney injury. The transcriptome of ST2+ Tregs was enriched for reparative factors including AREG. Lack of ST2 or AREG in Tregs worsened kidney injury. Tregs protected kidney organoids from hypoxia in ST2 and AREG-dependent manner. Thus Treg-based approaches could be of benefit for resolution of renal injury.

Growth Differentiation Factor GDF 15 (“Protein of Senility”) under Conditions of Oxidative Stress and Intermittent Nocturnal Hypoxia in Patients with Sleep Apnea Syndrome

Growth Differentiation Factor GDF 15 (“Protein of Senility”) under Conditions of Oxidative Stress and Intermittent Nocturnal Hypoxia in Patients with Sleep Apnea Syndrome

Long-term trends in dissolved oxygen and environmental parameters in Jinhae Bay, Korea: A 25-year analysis (1997–2021)

In recent decades, global oceanic dissolved oxygen (DO) levels have been consistently declining, leading to a notable increase in hypoxic zones. However, comprehensive information on the current trends of DO in Jinhae Bay remains scarce. This study investigated the long-term variations in bottom dissolved oxygen (DO) in Jinhae Bay, specifically focusing on recurring occurrences of oxygen-deficient water (ODW) in August, coinciding with the lowest average DO levels with the most stratified water. ODW events predominantly manifested in the inner bay, while the outer bay exhibited fewer instances due to robust water exchange processes. Analysis of the Low DO group revealed higher surface temperature and salinity, indicating diminished oxygen solubility compared to the High DO group. Lower Chemical oxygen demand (COD) and chlorophyll-a (Chl-a) values in the Low DO group suggested enhanced bacterial decomposition and subdued photosynthesis, in contrast to the High DO group. Over the last 25 years, Jinhae Bay has experienced a discernible decline in bottom DO concentrations. Contrastingly, surface temperature has exhibited a consistent upward trend, notably accelerating in the last 12 years, indicating reduced oxygen solubility. Notably, a substantial reduction in bottom DO levels was observed in the outer bay, previously considered less susceptible to hypoxic conditions. Furthermore, a concurrent decrease in pH highlights the urgency for a comprehensive investigation encompassing both summer hypoxia and seawater acidification, crucial for protecting Jinhae Bay's ecosystem from further deterioration.

Effects of Intermittent and Chronic Hypoxia on Fish Size and Nutrient Metabolism in Tiger Puffer (Takifugu rubripes).

Intermittent and chronic hypoxia are common stresses to marine fish, but the different responses of fish to intermittent and chronic hypoxia have not been well-known. In this study, tiger puffers were farmed in normoxia conditions (NO, 6.5 ± 0.5 mg/L), intermittent hypoxia (IH, 6.5 ± 0.5 mg/L in the day and 3.5 ± 0.5 mg/L in the night), or choric hypoxia (CH, 3.5 ± 0.5 mg/L) conditions for 4 weeks, after which the growth, nutrient metabolism and three hifα isoforms expression were measured. Both intermittent and chronic hypoxia decreased the fish growth and visceral weight but increased the feed conversion ratio and blood hemoglobin content. Chronic hypoxia but not intermittent hypoxia promoted protein synthesis and whole-fish protein content by activating mtor gene expression and promoted the glycolysis pathway by activating gene expression of hif1α and hif2α. Intermittent hypoxia but not chronic hypoxia decreased the hepatic lipid synthesis by inhibiting fasn and srebf1 gene expression. Meanwhile, intermittent hypoxia reduced the monounsaturated fatty acid content but increased the n-3 polyunsaturated fatty acids percentage. The results of this study clarified the adaptive mechanism of tiger puffer to intermittent and chronic hypoxia, which provides important information about mechanisms of hypoxia adaption in fish.

CoCl2‐induced glioma hypoxia environment enhances CD47‐SIRPα to promote tumor immune evasion

AbstractElevated levels of tumor‐associated macrophages and microglia in the immune microenvironment of malignant gliomas promote tumor growth and progression. Although immune evasion has been implicated in these processes, the mechanisms underlying the regulation of CD47‐SIRPα‐mediated immune evasion under hypoxic conditions remain unclear. Therefore, this study aimed to explore the mechanisms through which CD47‐SIRPα modulates immune evasion in a cobalt chloride (CoCl2)‐induced hypoxic microenvironment of malignant gliomas. Human and mouse glioma cell lines were used to investigate immune evasion in vitro. After membrane protein extraction and nucleoplasmic isolation, we downregulated the expression levels of transport receptors to elucidate the regulation of CD47‐SIRPα transport. The CoCl2‐induced hypoxic microenvironment attenuated microglial phagocytosis in glioma cells. Enhanced CD47‐SIRPα interaction promoted immune evasion, which negatively affected tumor clearance. In addition, the intracellular transport of CD47 was promoted in the CoCl2‐induced hypoxic state. This process was regulated by regulator of chromosome condensation 1 (RCC1) and sortilin in the nuclear cytoplasm and cytoplasmic membrane, respectively. These results demonstrate the CD47‐SIRPα‐mediated immune escape mechanism of the CoCl2‐induced glioma hypoxic environment, which is associated with enhanced intracellular transport of CD47. Our findings provide a theoretical basis for the potential development of novel therapies targeting CD47‐SIRPα.

Low cytoplasmic NUB1 protein exerts hypoxic cell death with poorer prognosis in oestrogen receptor negative breast cancer patients

Current prognostic biomarkers fall short in stratifying Oestrogen receptor (ER)-negative breast cancer patients regarding tumour progression risk at diagnosis. The role of AIPL1 in activating its tumour suppressor client protein, NEDD8 Ultimate Buster-1 (NUB1) remains unknown in cancer. Our study demonstrated how downregulated AIPL1 results in the deactivated NUB1 protein under hypoxic conditions. We examined the AIPL1-NUB1 pathwayin vitro using cell lines i.e. MCF-7, MDA-MB-231, RCC4 etc. NUB1 expression was assessed using Oncomine, and cBioPortal was performed to assess NUB1′s prognostic significance in human cancers. In the John Radcliffe Hospital cohort (n = 122), immunohistochemistry analysis revealed downregulated AIPL1 (Log2 fold change=-0.28; p < 0.001) and upregulated NUB1 transcripts (Log2 fold change=0.59; p < 0.001) compared to adjacent normal tissues. In severe chronic hypoxia, multimerised AIPL1 localisedin the cytoplasm while NUB1 protein migrated to the nucleus, where the absence of NUB1 nuclear localisation led to cell cycle arrest. Biopsies showed that patients with lower cytoplasmic NUB1 expression (n = 57) had poorer overall survival compared to those with higher cytoplasmic expression (n = 57), HR=1.78; 95 % CI=1.01–3.35, p = 0.048. Low NUB1 protein levels in both normoxic and hypoxic conditions were associated with cell cycle arrest and upregulation ofp21 and p27 in breast cancer cell lines, correlating significantly withpoorer survival outcomes in all breast cancer and ER-negative breast cancer patients.

ZBTB7A forms a heterodimer with ZBTB2 and inhibits ZBTB2 homodimerization required for full activation of HIF-1

Hypoxia-inducible factor 1 (HIF-1), recognized as a master transcription factor for adaptation to hypoxia, is associated with malignant characteristics and therapy resistance in cancers. It has become clear that cofactors such as ZBTB2 are critical for the full activation of HIF-1; however, the mechanisms downregulating the ZBTB2-HIF-1 axis remain poorly understood. In this study, we identified ZBTB7A as a negative regulator of ZBTB2 by analyzing protein sequences and structures. We found that ZBTB7A forms a heterodimer with ZBTB2, inhibits ZBTB2 homodimerization necessary for the full expression of ZBTB2-HIF-1 downstream genes, and ultimately delays the proliferation of cancer cells under hypoxic conditions. The Cancer Genome Atlas (TCGA) analyses revealed that overall survival is better in patients with high ZBTB7A expression in their tumor tissues. These findings highlight the potential of targeting the ZBTB7A-ZBTB2 interaction as a novel therapeutic strategy to inhibit HIF-1 activity and improve treatment outcomes in hypoxia-related cancers.

Endonuclear Circ-calm4 regulates ferroptosis via a circR-Loop of the COMP gene in pulmonary artery smooth muscle cells

Pulmonary hypertension (PH) is a serious pulmonary vascular disease characterized by vascular remodeling. Circular RNAs (CircRNAs) play important roles in pulmonary hypertension, but the mechanism of PH is not fully understood, particularly the roles of circRNAs located in the nucleus. Circ-calmodulin 4 (circ-calm4) is expressed in both the cytoplasm and the nucleus of pulmonary arterial smooth muscle cells (PASMCs). This study aimed to investigate the role of endonuclear circ-calm4 in PH and elucidate its underlying signaling pathway in ferroptosis. Immunoblotting, quantitative real-time polymerase chain reaction (PCR), malondialdehyde (MDA) assay, immunofluorescence, iron assay, dot blot, and chromatin immunoprecipitation (ChIP) were performed to investigate the role of endonuclear circ-calm4 in PASMC ferroptosis. Increased endonuclear circ-calm4 facilitated ferroptosis in PASMCs under hypoxic conditions. We further identified the cartilage oligomeric matrix protein (COMP) as a downstream effector of circ-calm4 that contributed to the occurrence of hypoxia-induced ferroptosis in PASMCs. Importantly, we confirmed that endonuclear circ-calm4 formed circR-loops with the promoter region of the COMP gene and negatively regulated its expression. Inhibition of COMP restored the phenotypes related to ferroptosis under hypoxia stimulation combined with antisense oligonucleotide (ASO)-circ-calm4 treatment. We conclude that the circ-calm4/COMP axis contributed to hypoxia-induced ferroptosis in PASMCs and that circ-calm4 formed circR-loops with the COMP promoter in the nucleus and negatively regulated its expression. The circ-calm4/COMP axis may be useful for the design of therapeutic strategies for protecting cellular functionality against ferroptosis and pulmonary hypertension.

Molecular Engineering of Pure Superoxide Radical Photogenerator for Hypoxia-Tolerant Tumor Theranostics.

Photodynamic therapy (PDT) is a promising cancer treatment, but limited oxygen supply in tumors (hypoxia) can hinder its effectiveness. This is because traditional PDT relies on Type-II reactions that require oxygen. Type-I photosensitizers (PSs) offer a promising approach to overcome the limitations of tumor photodynamic therapy (PDT) in hypoxic environments. To leverage the advantages of Type-I PDT, the design and evaluation of a series of Type-I PSs for developing pure Type-1 PSs, by incorporating benzene, thiophene, or bithiophene into the donor-acceptor molecular skeleton are reported. Among them, CTTI (with bithiophene) shows the best performance, generating the most superoxide radical (O2 •-) upon light irradiation. Importantly, CTTI exclusively produced superoxide radicals, avoiding the less effective Type-II pathway. This efficiency is due to CTTI's energy gap and low reduction potential, which favor electron transfer to oxygen for O2 •- generation. Finally, CTTI NPs are successfully fabricated by encapsulating CTTI into liposomes, and validated to be effective in killing tumor cells, even under hypoxic conditions, making them promising hypoxia-tolerant tumor phototheranostic agents in both in vitro and in vivo applications.

The role of LPA receptor signaling in modulating cellular responses of colon cancer cells co-cultured with lymphoid endothelial cells under hypoxic stress

Solid tumors are formed by cancer cells and the surrounding non-cancer stromal cells under hypoxic conditions, collectively referred to as the tumor microenvironment (TME). Lysophosphatidic acid (LPA) receptor (LPA1 to LPA6) signaling is crucial in regulating tumor progression. This study investigated the impact of LPA receptor signaling on the biological behaviors of colon cancer DLD-1 cells co-cultured with lymphatic endothelial SVEC4–10 cells under hypoxic conditions. Expression levels of LPAR1, LPAR2 and LPAR5 genes were significantly higher in DLD-1 cells co-cultured with SVEC4–10 cells compared to those cultured alone. Co-culturing with SVEC4–10 cells increased the motility of DLD-1 cells at 21 % O2. LPA stimulated the motility of DLD-1 cells co-cultured with SVEC4–10 cells but had no effect on DLD-1 cells cultured alone. Furthermore, under 1 % O2 conditions, expression levels of LPAR1, LPAR2, and LPAR5 genes were markedly elevated in DLD-1 cells co-cultured with SVEC4–10 cells compared to 21 % O2. The motility of DLD-1 cells co-cultured with SVEC4–10 cells was enhanced under 1 % O2 conditions. Viability of DLD-1 cells to fluorouracil (5-FU) in SVEC4–10 cell supernatants increased at 21 % O2 and decreased at 1 % O2. Additionally, the LPA2 agonist GRI-977143 increased viability to 5-FU. These findings indicate that LPA receptor signaling plays a critical role in regulating the biological behaviors of DLD-1 cells co-cultured with SVEC4–10 cells under hypoxic conditions.

LAT1 expression in colorectal cancer cells is unresponsive to HIF-1/2α accumulation under experimental hypoxia

L-type amino acid transporter 1 (LAT1) is upregulated in various cancer types and contributes to disease progression. Previous studies have demonstrated or suggested that hypoxia-inducible factors (HIFs), the key transcription factors in hypoxic responses, control the expression of LAT1 gene in several types of cancer cells. However, this regulatory relationship has not been investigated yet in colorectal cancer (CRC), one of the cancer types in which the increased LAT1 expression holds prognostic significance. In this study, we found that neither LAT1 mRNA nor protein is induced under hypoxic condition (1% O2) in CRC HT-29 cells in vitro, regardless of the prominent HIF-1/2α accumulation and HIFs-dependent upregulation of glucose transporter 1. The hypoxic treatment generally did not increase either the mRNA or protein expression of LAT1 in eight CRC cell lines tested, in contrast to the pronounced upregulation by amino acid restriction. Interestingly, knockdown of von Hippel-Lindau ubiquitin ligase to inhibit the proteasomal degradation of HIFs caused an accumulation of HIF-2α and increased the LAT1 expression in certain CRC cell lines. This study contributes to delineating the molecular mechanisms responsible for the pathological expression of LAT1 in CRC cells, emphasizing the ambiguity of HIFs-dependent transcriptional upregulation of LAT1 across cancer cells.

The activity of therapeutic molecular cluster Ag5 is dependent on oxygen level and HIF-1 mediated signalling

Regions of hypoxia occur in most solid tumours and are known to significantly impact therapy response and patient prognosis. Ag5 is a recently reported silver molecular cluster which inhibits both glutathione and thioredoxin signalling therefore limiting cellular antioxidant capacity. Ag5 treatment significantly reduces cell viability in a range of cancer cell lines with little to no impact on non-transformed cells. Characterisation of redox homeostasis in hypoxia demonstrated an increase in reactive oxygen species and glutathione albeit with different kinetics. Significant Ag5-mediated loss of viability was observed in a range of hypoxic conditions which mimic the tumour microenvironment however, this effect was reduced compared to normoxic conditions. Reduced sensitivity to Ag5 in hypoxia was attributed to HIF-1 mediated signalling to reduce PDH via PDK1/3 activity and changes in mitochondrial oxygen availability. Importantly, the addition of Ag5 significantly increased radiation-induced cell death in hypoxic conditions associated with radioresistance. Together, these data demonstrate Ag5 is a potent and cancer specific agent which could be used effectively in combination with radiotherapy.

Metabolic cycles: A unifying concept for energy transfer in the heart

It is still debated whether changes in metabolic flux are cause or consequence of contractile dysfunction in non-ischemic heart disease. We have previously proposed a model of cardiac metabolism grounded in a series of six moiety-conserved, interconnected cycles. In view of a recent interest to augment oxygen availability in heart failure through iron supplementation, we integrated this intervention in terms of moiety conservation. Examining published work from both human and murine models, we argue this strategy restores a mitochondrial cycle of energy transfer by enhancing mitochondrial pyruvate carrier (MPC) expression and providing pyruvate as a substrate for carboxylation and anaplerosis. Metabolomic data from failing heart muscle reveal elevated pyruvate levels with a concomitant decrease in the levels of Krebs cycle intermediates. Additionally, MPC is downregulated in the same failing hearts, as well as under hypoxic conditions. MPC expression increases upon mechanical unloading in the failing human heart, as does contractile function. We note that MPC deficiency also alters expression of enzymes involved in pyruvate carboxylation and decarboxylation, increases intermediates of biosynthetic pathways, and eventually leads to cardiac hypertrophy and dilated cardiomyopathy. Collectively, we propose that an unbroken chain of moiety-conserved cycles facilitates energy transfer in the heart. We refer to the transport and subsequent carboxylation of pyruvate in the mitochondrial matrix as an example and a proposed target for metabolic support to reverse impaired contractile function.

γCyclodextrin-assisted Aqueous Extract of Cinnamon for Cancer and Stress Management.

Our goal was to investigate the use of Cyclodextrin in creating an aqueous extract of Cinnamon with a high content of its bioactive ingredients, validated by cell-based assays. Due to their safety and cost-effectiveness, natural compounds have garnered attention for cancer therapy, which often faces challenges related to drug toxicity and resistance. Cinnamon (Cinnamomum verum; also known as Ceylon Cinnamon) is a commonly used spice with a history in folk medicine for treating various ailments. However, its active ingredients suffer from poor solubility, stability, and bioavailability, which limits its use and benefits. We prepared γCyclodextrin (γCD)-assisted aqueous extract of Cinnamon (CD-CIN) and compared its activity with the DMSO extract (DM-CIN). The cells were exposed to CD-CIN and DM-CIN extracts under normal and stressed (oxidative, metal, and hypoxic) conditions and then analyzed for stress and cancerous phenotypes using various molecular assays. We found that CD-CIN possesses considerable anticancer activity that involves the activation of tumor suppressor proteins and DNA damage response. Low, non-toxic concentrations of DM-CIN and CD-CIN caused comparable inhibition of migration and invasion capability of cells, supported by molecular marker analyses. Furthermore, protection against oxidative, metal, and hypoxia stress, as well as induction of differentiation, was recorded in both DM-CIN and CD-CIN treated cells, as compared to the control. We report CD-CIN as a new economic and easy Cinnamon-derived resource that possesses considerable anticancer and antistress activities and hence warrants further chemical, in vitro, and in vivo studies.

Metformin Radiosensitizing Effect on Hypoxic Oral Squamous Cell Carcinoma Cells by GAPDH and TAGLN2.

Tumor hypoxia is associated with a poorer prognosis in cancer patients and can diminish the efficacy of radiation therapy (RT). This study investigates the potential of metformin to enhance radiosensitivity in hypoxic cancer cells. Preliminary experiments were conducted to validate the impact of hypoxia on radiation response. Reactive oxygen species (ROS) levels, cell migration, and cell death were assessed in hypoxic, radiated cells treated with metformin. Proteomic and ontological analyses were employed to identify molecular targets associated with the radiosensitizing effect of metformin. Proteomic and ontological findings were validated through patient samples and in vitro studies. Metformin amplified cell death, induced DNA fragmentation, decreased cell migration, and elevated ROS levels in hypoxic, radiated cells. Proteomic analyses revealed that GAPDH and TAGLN2 were identified as pivotal targets linked to the radiosensitizing effect of metformin. Oral cancer patients exhibited elevated levels of TAGLN2 and reduced levels of GAPDH. Metformin downregulated TAGLN2 and upregulated GAPDH in hypoxic, radiated cells. Additionally, metformin reduced levels of mutated p53. This study suggests that metformin can enhance radiosensitivity in hypoxic cells, operating through modulation of GAPDH and TAGLN2. Furthermore, metformin effectively reduces mutated p53 levels in radiated cells under hypoxic conditions.

Dysregulation of tetrahydrobiopterin metabolism in myalgic encephalomyelitis/chronic fatigue syndrome by pentose phosphate pathway.

Tetrahydrobiopterin (BH4) and its oxidized derivative dihydrobiopterin (BH2) were found to be strongly elevated in ME/CFS patients with orthostatic intolerance (ME + OI). However, the molecular mechanism of biopterin biogenesis is poorly understood in ME + OI subjects. Here, we report that the activation of the non-oxidative pentose phosphate pathway (PPP) plays a critical role in the biogenesis of biopterins (BH4 and BH2) in ME + OI subjects. Microarray-based gene screening followed by real-time PCR-based validation, ELISA assay, and finally enzyme kinetic studies of glucose-6-phosphate dehydrogenase (G6PDH), transaldolase (TALDO1), and transketolase (TK) enzymes revealed that the augmentation of anaerobic PPP is critical in the regulations of biopterins. To further investigate, we devised a novel cell culture strategy to induce non-oxidative PPP by treating human microglial cells with ribose-5-phosphate (R5P) under a hypoxic condition of 85%N2/10%CO2/5%O2 followed by the analysis of biopterin metabolism via ELISA, immunoblot, and dual immunocytochemical analyses. Moreover, the siRNA knocking down of the taldo1 gene strongly inhibited the bioavailability of phosphoribosyl pyrophosphate (PRPP), reduced the expressions of purine biosynthetic enzymes, attenuated GTP cyclohydrolase 1 (GTPCH1), and suppressed subsequent production of BH4 and its metabolic conversion to BH2 in R5P-treated and hypoxia-induced C20 human microglia cells. These results confirmed that the activation of non-oxidative PPP is indeed required for the upregulation of both BH4 and BH2 via the purine biosynthetic pathway. To test the functional role of ME + OI plasma-derived biopterins, exogenously added plasma samples of ME + OI plasma with high BH4 upregulated inducible nitric oxide synthase (iNOS) and nitric oxide (NO) in human microglial cells indicating that the non-oxidative PPP-induced-biopterins could stimulate inflammatory response in ME + OI patients. Taken together, our current research highlights that the induction of non-oxidative PPP regulates the biogenesis of biopterins contributing to ME/CFS pathogenesis.

Ultrasound-assisted water oxidation: unveiling the role of piezoelectric metal-oxide sonocatalysts for cancer treatment

Ultrasound radiation has been widely used in biomedical application for both diagnosis and therapy. Metal oxides nanoparticles (NPs), like ZnO or TiO2 NPs, have been widely demonstrated to act as excellent sonocatalysts and significantly enhance cavitation at their surface, making them optimal for sonodynamic cancer therapy. These NPs often possess semiconductive and piezoelectric properties that contribute to the complex phenomena occurring at the water-oxide interface during sonostimulation. Despite the great potential in applied sonocatalysis and water splitting, the complex mechanism that governs the phenomenon is still a research subject. This work investigates the role of piezoelectric ZnO micro- and nano-particles in ultrasound-assisted water oxidation. Three metal oxides presenting fundamental electronic and mechanical differences are evaluated in terms of ultrasound-triggered reactive oxygen species generation in aqueous media: electromechanically inert SiO2 NPs, semiconducting TiO2 NPs, piezoelectric and semiconducting ZnO micro- and nanoparticles with different surface areas and sizes. The presence of silver ions in the aqueous solution was further considered to impart a potential electron scavenging effects and better evaluate the oxygen generation performances of the different structures. Following sonoirradiation, the particles are optically and chemically analyzed to study the effect of sonostimulation at their surface. The production of gaseous molecular oxygen is measured, revealing the potential of piezoelectric particles to generate oxygen under hypoxic conditions typical of some cancer environments. Finally, the best candidates, i.e. ZnO nano and micro particles, were tested on osteosarcoma and glioblastoma cell lines to demonstrate their potential for cancer treatment.

CB-839 induces reversible dormancy in lung tumor-cells

Glutaminase inhibitors are currently being explored as potential treatments for cancer. This study aimed to elucidate the molecular mechanisms underlying the effects of CB-839 on lung tumor cell lines compared to non-tumor cell lines. Viability assays based on NADPH-dependent dehydrogenases activity, ATP energy production, or mitochondrial reductase activity were used to determine that CB-839 caused significant tumor cell specific inhibition of cellular functions. Clonogenic survival assay revealed a dose dependent reduction in clonogenic survival of various lung tumor cells presenting estimated IC50 values between 10 and 90 nM, while no effect on non-tumor cells was observed. CB-839 led to a 20% reduction in glutaminase (GLS1, a mitochondrial enzyme that catalyzes the conversion of glutamine to glutamate) activity, and a dose-dependent reduced glutamine consumption in tumor cells and had no effect on non-tumor cells. Cell cycle analysis showed the CB-839 did not lead to cell cycle arrest. Apoptosis and necrosis assays revealed an only slight increase in apoptosis in tumor cells. Furthermore, a trypan blue exclusion assay revealed about 40% growth reduction in tumor cells at 0.1–1 μM CB-839 treatment. Surprisingly, treated cells resumed normal growth when re-plated in a drug-free medium, demonstrating reversibility. In hypoxic conditions, CB-839's effect on clonogenic survival was amplified in a dose dependent manner consistent with increased role of GLS1 for energy production under hypoxic conditions. In conclusion, these results suggest CB-839 efficacy is linked to temporary and reversible reduction in glutamine utilization suggesting induction of dormancy.

Regulating Charge Transfer in Cyanine Dyes: A Universal Methodology for Enhancing Cancer Phototherapeutic Efficacy.

ConspectusDue to the advantages of spatiotemporal selectivity and inherent noninvasiveness, cancer phototherapy, which includes both photodynamic therapy (PDT) and photothermal therapy (PTT), has garnered significant attention in recent years as a promising cancer treatment. Despite the commendable progress in this field, persistent challenges remain. In PDT, limitations in dyes manifest as low intersystem crossing (ISC) efficiency and oxygen-dependent photoactivity, resulting in unsatisfactory performance, particularly under hypoxic conditions. Similarly, PTT encounters consistent insufficiencies in the photothermal conversion efficiency (PCE) of dyes. Additionally, the suboptimal phototherapeutic efficacy often exhibits a limited immune response. These factors collectively impose significant constraints on phototherapy in oncological applications, leading to limited tumor inhibition, tumor recurrence, and even metastasis.Unlike strategies that rely on external assistance with complicated systems, manipulating excited-state deactivation pathways in biocompatible dyes offers a universal way to systematically address these challenges. Our group has devoted considerable effort to achieving this goal. In this Account, we present and discuss our journey in optimizing excited-state energy-release pathways through regulating molecular charge transfer based on cyanine dyes, which are renowned for their exceptional photophysical properties and harmonious biocompatibility. The investigation begins with the introduction of amino groups in the meso position of a heptamethine cyanine dye, where the intramolecular charge transfer (ICT) effect causes a significant enlargement of the Stokes shift. Subsequently, ICT induced by introducing functional electron-deficient groups in cyanines is found to decrease the overlap of electron distribution or narrow the energy gaps of molecular frontier orbitals. Such modifications result in a reduction of the energy gaps between singlet and triplet states or an improvement in internal conversion, ultimately promoting phototherapy efficacy in both primary and distant tumors. Furthermore, with the intensification of the charge transfer effect aided by light, photoinduced intramolecular electron transfer occurs in some cyanines, leading to complete charge separation in the excited state. This process enhances the transition to the ground or triplet states, improving tumor phototherapy and inhibiting metastasis by increasing the PCE or the yield of reactive oxygen species, respectively. Shifting focus from intramolecular to intermolecular interactions, we successfully constructed and explored cyanines based on intermolecular charge transfer. These dyes, with excited-state dynamics mimicking natural photosynthesis, generate radicals and facilitate oxygen-independent hypoxic tumor PDT. Finally, we outlined the existing challenges and future directions for optimizing phototherapeutic efficacy by regulating molecular charge transfer. This Account provides molecular-level insights into improving phototherapeutic performance, offering valuable perspectives, and inspiring the development of functional dyes in other application fields.

The Effects of Hypoxia on the Immune-Metabolic Interplay in Liver Cancer.

M2-like macrophages promote tumor growth and cancer immune evasion. This study used an in vitro model to investigate how hypoxia and tumor metabolism affect macrophage polarization. Liver cancer cells (HepG2 and VX2) and macrophages (THP1) were cultured under hypoxic (0.1% O2) and normoxic (21% O2) conditions with varying glucose levels (2 g/L or 4.5 g/L). Viability assays and extracellular pH (pHe) measurements were conducted over 96 hours. Macrophages were exposed to the tumor-conditioned medium (TCM) from the cancer cells, and polarization was assessed using arginase and nitrite assays. GC-MS-based metabolic profiling quantified TCM meta-bolites and correlated them with M2 polarization. The results showed that pHe in TCMs decreased more under hypoxia than normoxia (p < 0.0001), independent of glucose levels. The arginase assay showed hypoxia significantly induced the M2 polarization of macrophages (control group: p = 0.0120,0.1%VX2-TCM group: p = 0.0149, 0.1%HepG2-TCM group: p < 0.0001, 0.1%VX2-TCMHG group: p = 0.0001, and 0.1%HepG2-TCMHG group: p < 0.0001). TCMs also induced M2 polarization under normoxic conditions, but the strongest M2 polarization occurred when both tumor cells and macrophages were incubated under hypoxia with high glucose levels. Metabolomics revealed that several metabolites, particularly lactate, were correlated with hypoxia and M2 polarization. Under normoxia, elevated 2-amino-butanoic acid (2A-BA) strongly correlated with M2 polarization. These findings suggest that targeting tumor hypoxia could mitigate immune evasion in liver tumors. Lactate drives acidity in hypoxic tumors, while 2A-BA could be a therapeutic target for overcoming immunosuppression in normoxic conditions.