Search

Ultrasound (US)-induced sonodynamic therapy (SDT) is an efficient and precise method against tumor, and the integration of multiple cancer therapies has been proved as a promising strategy for better therapeutic effects. Herein, for the first time, a multifunctional nanoreactor has been fabricated by integrating Fe-MIL-88B-NH 2 , PFC-1, and glucose oxidase (GO x ) to form urchin-like Fe-MIL-88B-NH 2 @PFC-1-GO x (MPG) nanoparticles as Fenton's reagent, a sonosensitizer, and a tumor microenvironment (TME) modulator. In detail, MPG can generate • OH for chemodynamic therapy (CDT) and deplete glutathione (GSH) to alleviate the antioxidant ability of cancer cells. Moreover, catalase (CAT)-like MPG can react with H 2 O 2 to generate O 2 for relieving hypoxia in TME, enhancing GO x -catalyzed glucose oxidation to produce H 2 O 2 and gluconic acid. Then, the regenerated H 2 O 2 can promote the Fenton reaction to achieve GO x catalysis-enhanced CDT. Owing to its large π-electron conjugated system, MPG also serves as an ideal sonosensitizer, realizing a burst generation of 1 O 2 under US irradiation for efficient SDT. Therefore, the tumor treatment will be notably enhanced by MPG-based synergetic CDT/SDT/starvation therapy via a series of cascade reactions. Overall, this work develops a versatile nanoreactor with improved tumor treatment effectiveness and broadens the application prospects of porous materials in the field of biomedical research.

Hypoxia is associated with tumor aggressiveness and poor prognosis, including breast cancer. Low oxygen levels induces global genomic hypomethylation and hypermethylation of specific loci in tumor cells. DNA methylation is a reversible epigenetic modification, usually associated with gene silencing, contributing to carcinogenesis and tumor progression. Since the effects of DNA methyltransferase inhibitor are context-dependent and as there is little data comparing their molecular effects in normoxic and hypoxic microenvironments in breast cancer, this study aimed to understand the gene expression profiles and molecular effects in response to treatment with DNA methyltransferase inhibitor in normoxia and hypoxia, using the breast cancer model. For this, a cDNA microarray was used to analyze the changes in the transcriptome upon treatment with DNA methyltransferase inhibitor (5-Aza-2'-deoxycytidine: 5-Aza-2'-dC), in normoxia and hypoxia. Furthermore, immunocytochemistry was performed to investigate the effect of 5-Aza-2'-dC on NF-κB/p65 inflammation regulator subcellular localization and expression, in normoxia and hypoxia conditions. We observed that proinflammatory pathways were upregulated by treatment with 5-Aza-2'-dC, in both conditions. However, treatment with 5-Aza-2'-dC in normoxia showed a greater amount of overexpressed proinflammatory pathways than 5-Aza-2'-dC in hypoxia. In this sense, we observed that the NF-κB expression increased only upon 5-Aza-2'-dC in normoxia. Moreover, nuclear staining for NF-κB and NF-κB target genes upregulation, IL1A and IL1B, were also observed after 5-Aza-2'-dC in normoxia. Our results suggest that 5-Aza-2'-dC induces a greater inflammatory change, at the molecular levels, in normoxic than hypoxic tumor microenvironment. These data may support further studies and expand the understanding of the DNA methyltransferase inhibitor effects in different tumor contexts.

Myeloma cells produce excessive levels of dickkopf-1 (DKK1), which mediates the inhibition of Wnt signaling in osteoblasts, leading to multiple myeloma (MM) bone disease. Nevertheless, the precise mechanisms underlying DKK1 overexpression in myeloma remain incompletely understood. Herein, we provide evidence that hypoxia promotes DKK1 expression in myeloma cells. Under hypoxic conditions, p38 kinase phosphorylated cAMP-responsive element-binding protein (CREB) and drove its nuclear import to activate DKK1 transcription. In addition, high levels of DKK1 were associated with the presence of focal bone lesions in patients with t(4;14) MM, overexpressing the histone methyltransferase MMSET, which was identified as a downstream target gene of hypoxia-inducible factor (HIF)-1α. Furthermore, we found that CREB could recruit MMSET, leading to the stabilization of HIF-1α protein and the increased dimethylation of histone H3 at lysine 36 on the DKK1 promoter. Knockdown of CREB in myeloma cells alleviated the suppression of osteoblastogenesis by myeloma-secreted DKK1 in vitro. Combined treatment with a CREB inhibitor and the hypoxia-activated prodrug TH-302 (evofosfamide) significantly reduced MM-induced bone destruction in vivo. Taken together, our findings reveal that hypoxia and a cytogenetic abnormality regulate DKK1 expression in myeloma cells, and provide an additional rationale for the development of therapeutic strategies that interrupt DKK1 to cure MM.

Modulating the hypoxic microenvironment is the priority for tumor treatment. Cytometalated iridium(iii)-metformin conjugates were synthesized for treating hypoxic cancer cells for the first time, which alleviate hypoxia via mitochondria respiration inhibition, thus displaying 10-fold higher cytotoxicity, emerging anti-metastasis and anti-inflammatory activities than a metformin-free Ir(iii) complex and cisplatin against hypoxic cancer cells.

Background: In hypoxic tumors, positive feedback between oncogenic KRAS and HIF-1α involves impressive metabolic changes correlating with drug resistance and poor prognosis in colorectal cancer. Up to date, designed KRAS-targeting molecules do not show clear benefits in patient overall survival (POS) so pharmacological modulation of aberrant tricarboxylic acid (TCA) cycle in hypoxic cancer has been proposed as a metabolic vulnerability of KRAS-driven tumors. Methods: Annexin V-FITC and cell viability assays were carried out in order to verify vitamin C citotoxicity in KRAS mutant SW480 and DLD1 as well as in Immortalized Human Colonic Epithelial Cells (HCEC). HIF1a expression and activity were determined by western blot and functional analysis assays. HIF1a direct targets GLUT1 and PDK1 expression was checked using western blot and qRT-PCR. Inmunohistochemical assays were perfomed in tumors derived from murine xenografts in order to validate previous observations in vivo . Vitamin C dependent PDH expression and activity modulation were detected by western blot and colorimetric activity assays. Acetyl-Coa levels and citrate synthase activity were assessed using colorimetric/fluorometric activity assays. Mitochondrial membrane potential (Δ ψ ) and cell ATP levels were assayed using fluorometric and luminescent test. Results: PDK-1 in KRAS mutant CRC cells and murine xenografts was downregulated using pharmacological doses of vitamin C through the proline hydroxylation (Pro402) of the Hypoxia inducible factor-1(HIF-1)α, correlating with decreased expression of the glucose transporter 1 (GLUT-1) in both models. Vitamin C induced remarkable ATP depletion, rapid mitochondrial Δ ψ dissipation and diminished pyruvate dehydrogenase E1-α phosphorylation at Serine 293, then boosting PDH and citrate synthase activity. Conclusion: We report a striking and previously non reported role of vitamin C in the regulation of the pyruvate dehydrogenase (PDH) activity, then modulating the TCA cycle and mitochondrial metabolism in KRAS mutant colon cancer. Potential impact of vitamin C in the clinical management of anti-EGFR chemoresistant colorectal neoplasias should be further considered., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Hypoxic tumors overexpress membrane-bound isozymes of carbonic anhydrase (CA) CA IX and CA XII, which play key roles in tumor pH homeostasis under hypoxia. Selective inhibition of these CA isozymes has the potential to generate pH imbalances that can lead to tumor cell death. Since these isozymes are dimeric, we designed a series of bifunctional PEGylated CA inhibitors (CAIs) through the attachment of our preoptimized CAI warhead 1,3,4-thiadiazole-2-sulfonamide to polyethylene glycol (PEG) backbones with lengths ranging from 1 KDa to 20 KDa via a succinyl linker. A detailed structure-thermal properties and structure-biological activity relationship study was conducted via differential scanning calorimetry (DSC) and via viability testing in 2D and 3D (tumor spheroids) cancer cell models, either CA IX positive (HT-29 colon cancer, MDA-MB 231 breast cancer, and SKOV-3 ovarian cancer) or CA IX negative (NCI-H23 lung cancer). We identified PEGylated CAIs DTP1K 28 , DTP2K 23 , and DTP3.4K 29 , bearing short and medium PEG backbones, as the most efficient conjugates under both normoxic and hypoxic conditions, and in the tumor spheroid models. PEGylated CAIs did not affect the cell viability of CA IX-negative NCI-H23 tumor spheroids, thus confirming a CA IX-mediated cell killing for these potential anticancer agents.

The outcome of radiotherapy is significantly restricted by tumor hypoxia. To overcome this obstacle, one prevalent solution is to increase intratumoral oxygen supply. However, its effectiveness is often limited by the high metabolic demand for O 2 by cancer cells. Herein, we develop a hybrid semiconducting organosilica-based O 2 nanoeconomizer pHPFON-NO/O 2 to combat tumor hypoxia. Our solution is twofold: first, the pHPFON-NO/O 2 interacts with the acidic tumor microenvironment to release NO for endogenous O 2 conservation; second, it releases O 2 in response to mild photothermal effect to enable exogenous O 2 infusion. Additionally, the photothermal effect can be increased to eradicate tumor residues with radioresistant properties due to other factors. This "reducing expenditure of O 2 and broadening sources" strategy significantly alleviates tumor hypoxia in multiple ways, greatly enhances the efficacy of radiotherapy both in vitro and in vivo, and demonstrates the synergy between on-demand temperature-controlled photothermal and oxygen-elevated radiotherapy for complete tumor response.

Photodynamic therapy (PDT) is a minimally invasive clinical protocol that combines a nontoxic photosensitizer (PS), appropriate visible light, and molecular oxygen for cancer treatment. This triad generates reactive oxygen species (ROS) in situ , leading to different cell death pathways and limiting the arrival of nutrients by irreversible destruction of the tumor vascular system. Despite the number of formulations and applications available, the advancement of therapy is hindered by some characteristics such as the hypoxic condition of solid tumors and the limited energy density (light fluence) that reaches the target. As a result, the use of PDT as a definitive monotherapy for cancer is generally restricted to pretumor lesions or neoplastic tissue of approximately 1 cm in size. To expand this limitation, researchers have synthesized functional nanoparticles (NPs) capable of carrying classical photosensitizers with self-supplying oxygen as well as targeting specific organelles such as mitochondria and lysosomes. This has improved outcomes in vitro and in vivo . This review highlights the basis of PDT, many of the most commonly used strategies of functionalization of smart NPs, and their potential to break the current limits of the classical protocol of PDT against cancer. The application and future perspectives of the multifunctional nanoparticles in PDT are also discussed in some detail.

Attributable to its late diagnosis, early metastasis, and poor prognosis, pancreatic cancer remains one of the most lethal diseases worldwide. Unlike other solid tumors, pancreatic cancer harbors ample stromal cells and abundant extracellular matrix but lacks vascularization, resulting in persistent and severe hypoxia within the tumor. Hypoxic microenvironment has extensive effects on biological behaviors or malignant phenotypes of pancreatic cancer, including metabolic reprogramming, cancer stemness, invasion and metastasis, and pathological angiogenesis, which synergistically contribute to development and therapeutic resistance of pancreatic cancer. Through various mechanisms including but not confined to maintenance of redox homeostasis, activation of autophagy, epigenetic regulation, and those induced by hypoxia-inducible factors, intratumoral hypoxia drives the above biological processes in pancreatic cancer. Recognizing the pivotal roles of hypoxia in pancreatic cancer progression and therapies, hypoxia-based antitumoral strategies have been continuously developed over the recent years, some of which have been applied in clinical trials to evaluate their efficacy and safety in combinatory therapies for patients with pancreatic cancer. In this review, we discuss the molecular mechanisms underlying hypoxia-induced aggressive and therapeutically resistant phenotypes in both pancreatic cancerous and stromal cells. Additionally, we focus more on innovative therapies targeting the tumor hypoxic microenvironment itself, which hold great potential to overcome the resistance to chemotherapy and radiotherapy and to enhance antitumor efficacy and reduce toxicity to normal tissues.

Sulfoglycolipid, SQAP, is a radiosensitizing agent that makes tumor cells more sensitive to radiation therapy. A previous study revealed that SQAP induced the degradation of hypoxia-inducible factor-1α (HIF-1α) and inhibited angiogenesis in a hepatoma model mouse. Herein, we examined the biological activities of SQAP against hepatocarcinoma cells under low oxygen conditions. Cell growth inhibition of SQAP under hypoxic conditions was significantly higher than that under normoxic conditions. In addition, SQAP was found to impair the expression of histone deacetylase (HDAC) under low oxygen conditions. Our present data suggested that SQAP induced the degradation of HIF-1α and then decreased the expression of HDAC1. Unlike known HDAC inhibitors, SQAP increased the acetylation level of histone in cells without inhibition of enzymatic activity of HDACs. Our data demonstrated hypoxia-specific unique properties of SQAP., (© The Author(s) 2021. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.)

Hypoxia plays a key role in tumor progression and resistance to radiotherapy. Expression of the transmembrane-tethered enzyme carbonic anhydrase IX (CA IX) is strongly induced by hypoxia. High CA IX expression levels correlate with poor prognosis in cancer patients. Previously, we showed that the downregulation of CA IX expression by siRNA interference and the inhibition of CA IX activity results in increased cytotoxicity, inhibition of migration and radiosensitization of hypoxic cancer cells. Betulinic acid (BA) is a natural compound derived from birch bark. It has shown promising anti-tumor effects due to its cancer cell specific cytotoxic properties. We have shown that BA inhibits the HIF-1α pathway, resulting in apoptosis, inhibition of migration and enhanced cytotoxicity of breast cancer cells. In this study, we investigate the effects of the novel betulin derivative 3-O-acetylbetulin (3-AC) and carbonic anhydrase inhibitors (CAI) octyl disulfamate (OCT) or 4-(3-[4-fluorophenyl]ureido)benzenesulfonamide (SLC-0111), on cellular and radiobiological parameters in MDA-MB-231 and MCF-7 cells. Treatment with 3-AC or OCT alone only caused moderate cytotoxicity, reduction in cell migration, ROS production and DNA damage. However, the combined treatment with 3-AC and CAI strongly enhanced radiosensitivity, increased cytotoxicity, inhibited cell motility and enhanced DNA damage. Our findings suggest that the combination of two bioactive drugs 3-AC and a CAI, such as OCT or SLC-0111, could be a promising therapeutic approach for targeting hypoxic tumor cells., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Betulinic acid and betulin show promising activity against cancers cells, but the mechanism of their action is still unclear. In this study, non-small cell lung cancer (NSCLC) cell lines: A549, H358 and NCI-H1703 were treated with betulinic acid and betulin under normoxic and hypoxic conditions as hypoxia is critically involved in the response of solid tumors to chemotherapy. The treatment inhibits viability and proliferation of NSCLC cells. The anti-proliferative effect was induced by G1 cell cycle arrest with increased p21 expression and decreased cyclin D1 and cyclin B1 expression. Additionally, downregulation of p-GSK3β activity and the Wnt/β-catenin pathway were also observed under hypoxia. We found that hypoxia increased apoptosis in NSCLC cells. Cell death was associated with changes in the expression of proteins involved in the mitochondrial apoptosis pathway and induction of apoptotic death by caspase activation. Additionally, hypoxia exposure deregulated HIF-1α and p53 expression levels. Importantly, treatment with betulinic acid and betulin reduced colony-forming ability under normoxia, however, only betulinic acid reduced clonogenic activity under hypoxia. Our findings that betulinic acid increases apoptotic cell death and clonogenic activity under hypoxic conditions reveal new attractive strategies for treating hypoxic cancer tumors, such as NSCLC., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Electrochemotherapy (ECT) is a new and promising treatment strategy for cancer treatment. The aim of this work is to investigate the effect of 900 MHz radiofrequency electromagnetic fields (RF-EMFs) on the mechanisms of ECT (low voltage, high frequency) including cell permeability in vitro, and tumor hypoxia, immune system response in vivo, and on volume of tumors treated with ECT (70 V/cm, 5 kHz). The 4T1 cells were exposed to RF-EMFs at 17, 162, or 349 µW/cm 2 power densities, using GSM900 simulator, 10 min. The cells were then put in individual groups, comprising of no treatment, chemotherapy, electric pulses (EPs), or ECT. The cell viability was evaluated. The mice with 4T1 tumor cells were exposed to RF field 10 min/day until the tumor volume reached about 8 mm. Then, the mice tumors were treated with ECT. Tumor hypoxia and immune system response was analyzed through immunohistochemistry (IHC) assay and ELISA technique, respectively. The volume of tumors was also calculated for 24 days following the treatment. The results showed that RF fields at 349 µW/cm 2 could increase tumor hypoxia induced by ECT and cause a significant increase of Interferon-gamma (IFN-γ) in comparison with group ECT alone. However, 900 MHz radiations did not affect the volume of tumors treated to ECT (70 V/cm, 5 kHz) significantly. In this study, 900 MHz EMF could improve some biological pathways induced by ECT. Such a positive effect could utilize in some other treatments to increase efficacy, which should be investigated in further research.

Photodynamic therapy (PDT) is an emerging alternative cancer treatment modality that utilizes photo-sensitivity to cause cell death upon photo-irradiation. However, PDT efficiency has been hampered by tumor hypoxia, blue-shifted excitation wavelengths, and the high dark toxicity of photo-sensitizers. We designed and synthesized two novel porphycene-based photosensitizers (TBPoS-OH and TBPoS-2OH) with potent photo-cytotoxicity and a LD 50 in the nM range under both normoxic and hypoxic conditions in a variety of cell types after photo-irradiation (λ = 640 ± 15 nm). Further studies showed fast-cellular uptake for TBPoS-OH that localized lysosomes and subsequently induced cell apoptosis via the lysosomal-mitochondrial pathway. Moreover, TBPoS-OH significantly reduced tumor growth in two xenografted mouse models bearing melanoma A375 and B16 cells. Finally, TBPoS-OH exhibited no obvious immunogenicity and toxicity to blood cells and major organs in mice. These data demonstrated that these two porphycene-based photosensitizers, especially TBPoS-OH, could be developed as a potential PDT modality., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Solid tumors inevitably develop radioresistance due to low oxygen partial pressure in the tumor microenvironment. Despite numerous attempts, there are still few effective ways to avoid the hypoxia-induced poor radiotherapeutic effect. To overcome this problem, platinum (Pt) nanodots were fabricated into a mesoporous bismuth (Bi)-based nanomaterial to construct a biodegradable nanocomposite BiPt-folic acid-modified amphiphilic polyethylene glycol (PFA). BiPt-PFA could act as a radiosensitizer to enhance the absorption of X-rays at the tumor site and simultaneously trigger response behaviors related to the tumor microenvironment due to the enrichment of materials in the tumor area. During this process, the Bi-based component consumed glutathione via coordination, thus altering the oxidative stress balance, while Pt nanoparticles catalyzed the decomposition of hydrogen peroxide to generate oxygen, thereby relieving tumor hypoxia. Both Pt and Bi thus co-modulated the tumor microenvironment to improve the radiotherapeutic effect. In addition, Pt dots in BiPt-PFA had strong near-infrared absorption ability and created an intensive photothermal therapeutic effect. Modulation of the tumor microenvironment could thus improve the therapeutic effect in hypoxic tumors by a combination of photothermal therapy and enhanced radiotherapy. BiPt-PFA, as a biodegradable nanocomposite, may thus modulate the tumor microenvironment to enhance the hypoxic tumor therapeutic effect by thermoradiotherapy.

Metastasis is the primary cause of death for most cancer patients, in which tumor-associated macrophages (TAMs) are involved through several mechanisms. While hitherto there is still a lack of study on exclusive elimination of TAMs to inhibit metastasis due to the difficulties in specific targeting of TAMs, we construct an extra- and intracellular stepwise-responsive delivery system p -(aminomethyl)benzoic acid (PAMB)/doxorubicin (DOX) to achieve specific TAM depletion for the first time, thereby preventing tumor metastasis. Once accumulated into the tumor, PAMB/DOX would stepwise responsively (hypoxia and reactive oxygen species (ROS) responsively) disintegrate to expose the TAM-targeting ligand and release DOX sequentially, which depletes TAMs effectively in vivo . Owing to the inhibition of extracellular matrix (ECM) degradation, neovascularization, and tumor invasion contributed by TAM depletion, lung metastasis was successfully inhibited. Furthermore, PAMB/DOX showed efficient inhibition against tumor growth as well as spontaneous metastasis formation when combined with additional chemotherapy, representing a safe and efficient nanoplatform to modulate the adverse tumor microenvironment via TAM elimination.

A facile approach to assemble catalase-like photosensitizing nanozymes with a self-oxygen-supplying ability was developed. The process involved Fe 3+ -driven self-assembly of fluorenylmethyloxycarbonyl (Fmoc)-protected amino acids. By adding a zinc(II) phthalocyanine-based photosensitizer (ZnPc) and the hypoxia-inducible factor 1 (HIF-1) inhibitor acriflavine (ACF) during the Fe 3+ -promoted self-assembly of Fmoc-protected cysteine (Fmoc-Cys), the nanovesicles Fmoc-Cys/Fe@Pc and Fmoc-Cys/Fe@Pc/ACF were prepared, which could be disassembled intracellularly. The released Fe 3+ could catalyze the transformation of H 2 O 2 enriched in cancer cells to oxygen efficiently, thereby ameliorating the hypoxic condition and promoting the photosensitizing activity of the released ZnPc. With an additional therapeutic component, Fmoc-Cys/Fe@Pc/ACF exhibited higher in vitro and in vivo photodynamic activities than Fmoc-Cys/Fe@Pc, demonstrating the synergistic effect of ZnPc and ACF., (© 2020 Wiley-VCH GmbH.)

Esophageal squamous cell carcinoma (ESCC), the most frequent esophageal cancer (EC) subtype, entails dismal prognosis. Hypoxia, a common feature of advanced ESCC, is involved in resistance to radiotherapy (RT). RT response in hypoxia might be modulated through epigenetic mechanisms, constituting novel targets to improve patient outcome. Post-translational methylation in histone can be partially modulated by histone lysine demethylases (KDMs), which specifically removes methyl groups in certain lysine residues. KDMs deregulation was associated with tumor aggressiveness and therapy failure. Thus, we sought to unveil the role of Jumonji C domain histone lysine demethylases (JmjC-KDMs) in ESCC radioresistance acquisition. The effectiveness of RT upon ESCC cells under hypoxic conditions was assessed by colony formation assay. KDM3A/KDM6B expression, and respective H3K9me2 and H3K27me3 target marks, were evaluated by RT-qPCR, Western blot, and immunofluorescence. Effect of JmjC-KDM inhibitor IOX1, as well as KDM3A knockdown, in in vitro functional cell behavior and RT response was assessed in ESCC under hypoxic conditions. In vivo effect of combined IOX1 and ionizing radiation treatment was evaluated in ESCC cells using CAM assay. KDM3A, KDM6B, HIF-1α, and CAIX immunoexpression was assessed in primary ESCC and normal esophagus. Herein, we found that hypoxia promoted ESCC radioresistance through increased KDM3A/KDM6B expression, enhancing cell survival and migration and decreasing DNA damage and apoptosis, in vitro. Exposure to IOX1 reverted these features, increasing ESCC radiosensitivity and decreasing ESCC microtumors size, in vivo. KDM3A was upregulated in ESCC tissues compared to the normal esophagus, associating and colocalizing with hypoxic markers (HIF-1α and CAIX). Therefore, KDM3A upregulation in ESCC cell lines and primary tumors associated with hypoxia, playing a critical role in EC aggressiveness and radioresistance. KDM3A targeting, concomitant with conventional RT, constitutes a promising strategy to improve ESCC patients' survival.

The innate hypoxic microenvironment of most solid tumors has a major influence on tumor growth, invasiveness, and distant metastasis. Here, a hypoxia-activated self-immolative prodrug of paclitaxel (PTX 2 -Azo) was synthesized and encapsulated by a peptide copolymer decorated with the photosensitizer chlorin e6 (Ce6) to prepare light-boosted PTX nanoparticle (Ce6/PTX 2 -Azo NP). In this nanoparticle, PTX 2 -Azo prevents premature drug leakage and realizes specific release in hypoxic tumor microenvironment and the photosensitizer Ce6 not only efficiently generates singlet oxygen under light irradiation but also acts as a positive amplifier to promote the release of PTX. The combination of photodynamic therapy (PDT) and chemotherapy results in excellent antitumor efficacy, demonstrating the great potential for synergistic cancer therapy., (© 2020 Wiley-VCH GmbH.)

Redox homeostasis is one of the main reasons for reactive oxygen species (ROS) tolerance in hypoxic tumors, limiting ROS-mediated tumor therapy. Proposed herein is a redox dyshomeostasis (RDH) strategy based on a nanoplatform, FeCysPW@ZIF-82@CAT Dz, to disrupt redox homeostasis, and its application to improve ROS-mediated hypoxic tumor therapy. Once endocytosed by tumor cells, the catalase DNAzyme (CAT Dz) loaded zeolitic imidazole framework-82 (ZIF-82@CAT Dz) shell can be degraded into Zn 2+ as cofactors for CAT Dz mediated CAT silencing and electrophilic ligands for glutathione (GSH) depletion under hypoxia, both of which lead to intracellular RDH and H 2 O 2 accumulation. These "disordered" cells show reduced resistance to ROS and are effectively killed by ferrous cysteine-phosphotungstate (FeCysPW) induced chemodynamic therapy (CDT). In vitro and in vivo data demonstrate that the pH/hypoxia/H 2 O 2 triple stimuli responsive nanocomposite can efficiently kill hypoxic tumors. Overall, the RDH strategy provides a new way of thinking about ROS-mediated treatment of hypoxic tumors., (© 2020 Wiley-VCH GmbH.)

Hypoxic microenvironment commonly occurred in the solid tumors considerably decreases the chemosensitivity of cancer cells. Salidroside (Sal), the main active ingredient of Rhodiola rosea , was shown to be able of regulating the tumor hypoxia micro-environment and enhancing the chemotherapeutic efficacy of drug-resistant cancer. Therefore, in this study, the Sal was co-loaded with Apatinib (Apa) by the PLGA-based nanoparticles (NPs) to improve the chemosensitivity of gastric cancer cells. Additionally, to improve the drug delivery efficacy, the tumor-homing peptide (iVR1 peptides) was further decorated on the surface of NPs. The tumor targeting ability of the peptides-functionalized nanoparticles (iVR1-NPs-Apa/Sal) was evaluated by in vitro and in vivo experiments. As the obtained results revealed that the iVR1-NPs-Apa/Sal displayed excellent tumor affinity than the unmodified ones (NPs-Apa/Sal), which in turn resulted in more efficient of anti-proliferation of gastric cancer cells and anti-tumor effect in vivo . In addition, compared with the cells or tumor-bearing mice only treaded by monotherapy of Apa, the cells or mice received combinational treatment of Apa and Sal showed obvious lower rate of growth, invasion, and migration or tumor growth and progress. Underlying mechanisms were further investigated and it was revealed that the anti-gastric cancer effect of Apa was signally improved by Sal through down-regulation the proliferation factors and increase the pro-apoptotic genes, as well as reprograming the tumor hypoxia micro-environment. In a word, the study showed that the Sal was able of improving the chemosensitivity of gastric cancer to Apa and the iVR1-NPs-Apa/Sal was capable of realizing highly efficient of tumor-targeting drug delivery.

Hypoxic tumour cells are radiation-resistant and are associated with poor therapeutic outcome. A poorly understood source of tumour hypoxia is unstable perfusion, which exposes tumour cells to varying oxygen tensions over time creating "transiently" hypoxic cells. Evidence suggests that angiotensin II type 1 receptor blockers (ARBs) can improve tumour perfusion by reducing collagen deposition from cancer associated fibroblasts (CAFs). However, the influence of ARBs on transient hypoxia and tumour radiation response is unknown. We tested how the ARBs losartan and telmisartan affected the solid tumour microenvironment, using fluorescent perfusion dyes and positron emission tomography to quantify tumour perfusion, and a combination of hypoxia markers and the hemorheological agent pentoxifylline to assess transient tumour hypoxia. We found CAF-containing tumours have reduced collagen I levels in response to telmisartan, but not losartan. Telmisartan significantly increased tumour blood flow, stabilized microregional tumour perfusion, and decreased tumour hypoxia by reducing the development of transient hypoxia. Telmisartan-treated tumours were more responsive to radiation, indicating that telmisartan reduces a therapeutically important population of transiently hypoxic tumour cells. Our findings indicate telmisartan is capable of modifying the tumour microenvironment to stabilize tumour perfusion, reduce transient hypoxia, and improve tumour radiation response., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The current trend of cancer therapy has changed from monotherapy to synergistic or combination therapies. Among the treatment strategies, photodynamic therapy (PDT) and starvation therapy are widely employed together. However, the therapeutic effect of these treatments could lead to strong resistance and poor prognosis due to tumor hypoxia. Therefore, a smart nanoplatform (MONs-GOx@MnO2-Ce6) has been constructed herein by the assembly of glucose oxidase (GOx)-coated mesoporous organosilica nanoparticles (MONs) and MnO2 nanosheets-chlorin e6 (Ce6), which form a nanosystem. Once MONs-GOx@MnO2-Ce6 enter tumor cells, it catalyzes the oxidation of glucose using oxygen (O2) and generates hydrogen peroxide (H2O2) and gluconic acid, the former of which may accelerate the decomposition of MnO2 nanosheets. The released MnO2 nanosheets would regenerate O2 in the presence of H2O2. In this case, MnO2 nanosheets serve as (i) a nanocarrier and fluorescence quencher for the photosensitizer Ce6, (ii) a degradable material that is activated by the tumor microenvironment (TME) for fluorescence recovery, and (iii) an O2-producing carrier that reacts with H2O2 for relieving hypoxia in the tumor, which contributes to the combined starvation/photodynamic cancer therapy since these treatment strategies need O2. MONs-GOx@MnO2-Ce6 could not only realize cancer cell imaging, but also reduce intracellular glucose uptake and Glut1 expression, inhibiting the metabolism of cancer cells. This strategy shows great potential for clinical applications.

The common existence of hypoxia within the tumor microenvironment severely restricts the efficacy of photodynamic therapy (PDT), which is attributed to the fact that the PDT process is strongly oxygen (O2) dependent. Here, a multifunctional composite (named CPCG), which combines polyethylene glycol (PEG) functionalized cerium oxide nanoparticles (CeO2) with photosensitizer chlorin e6 (Ce6) and glucose oxidase (GOx), is reported for generating O2 within the tumor microenvironment by the dual-path hydrogen peroxide (H2O2)-modulated ways to ameliorate hypoxia, thereby enhancing the PDT efficiency. This process is realized based on the dual enzyme-like activity of CeO2. The first modulated way is to transform the superoxide anion (O2˙-) into H2O2 by the superoxide dismutase-like activity of CeO2. The second modulated way is to decompose glucose into H2O2 through the catalysis of GOx. Subsequently, H2O2 generated from the above dual modulated ways can further produce O2via the catalase-like activity of CeO2. Additionally, the depletion of glucose could impede the nutrient supply to obtain starvation therapy. Both in vitro and in vivo experiments indicate that the CPCG composite could enhance the efficacy of photodynamic/starvation synergistic therapy. Therefore, this strategy offers great potential to modulate the O2 level in the tumor microenvironment for better therapeutic outcomes, and can act as a promising candidate in photodynamic/starvation synergistic therapy.

Hypoxia in the microenvironment is related to chemotherapy resistance, tumor progression, and metastasis. Curcumin, as a phenolic compound extracted from the turmeric, has been used as an anti-cancer agent with low toxicity in recent years. Since curcumin has inhibitory activities against hypoxia-inducible factors (HIFs) in several cancers, this study was conducted to examine the effect of curcumin on MCF-7 cells and cancer stem-like cells (CS-LCs) under hypoxic and normoxic conditions. CS-LCs were isolated from MCF-7 cells using the magnet activated cell sorting (MACS) method based on CD 44 + / CD 24 - surface markers. The effects of curcumin on the viability of MCF-7 cells and CS-LCs were examined in hypoxic and normoxic conditions using the MTT test. The effects of curcumin on apoptosis and cell cycle of CS-LCs and MCF-7 cells were analyzed using flow cytometry. Moreover, the inhibitory effects of curcumin on the levels of HIF-1 and HIF-2α protein in CS-LCs were investigated using the western blot method. Early apoptosis occurred in CSC-LCs more than MCF-7 cells under hypoxic conditions. Flow cytometry assay showed that curcumin caused cell cycle arrest of CSC-LCs and MCF-7 at the G2/M phase under hypoxic conditions while under normoxic conditions, arrest occurred at the G0/G1 phase in MCF-7 cells and at S and G2/M phases in CS-LCs. Based on the results, the curcumin inhibited the expression of HIF-1 by degrading ARNT in CS-LCs.In conclusion, curcumin has inhibitory effects on MCF- 7 cells and CS- LCs and thus may be used as an antitumor agent., Competing Interests: The authors declare no potential conflicts of interest., (Thieme. All rights reserved.)

Background: Hypoxia and HIF-1α are important regulators of tumour growth and angiogenesis and could be attractive targets for cancer therapeutics. Decursin is an active compound extracted from the roots of Angelica gigas and has been shown to have potent anti-cancer and anti-angiogenic activities. However, whether decursin regulates HIF-1α activity and immune responses under hypoxic conditions is not yet understood., Purpose: The aim of this study was to identify whether decursin exhibits anti-cancer activity by targeting HIF-1α., Study Design: We investigated whether decursin regulates HIF-1α protein stability and increases its degradation. In addition, we determined if decursin increases immune responses in tumour microenvironment to identify its hypoxia-associated anti-cancer activities., Materials and Methods: We performed the hypoxia-responsive element promoter-reporter assay, Western blot analysis, immune-fluorescence assay, semi-quantitative RT-PCR and ELISA for VEGF secretion, CCK-8 assay for cell proliferation, TUNEL assay for apoptosis and invasion assay in A549 human lung cancer or HCT116 human colon cancer cells. In vivo Lewis lung carcinoma (LLC) allograft mouse model was used to check tumour growth and immune responses in tumour microenvironment by immunohistochemistry analysis., Results: We observed that decursin inhibited HIF-1 activation under hypoxia by down-regulating the protein level of its subunit HIF-1α. It increased oxygen-dependant hydroxylation and ubiquitination of HIF-1α to promote HIF-1α degradation. Decursin also decreased mRNA expression of HIF-1α target genes. Decursin suppressed cancer cell proliferation, induced apoptosis and inhibited cancer cell invasion under hypoxia in cancer cells. In the allograft mouse tumour model, decursin reduced the hypoxic area and HIF-1α and PD-L1 expression. Infiltrating T cells (CD3+), helper T cells (CD4+) and cytotoxic (CD8+) T cells were accumulated, but regulatory T cells (Foxp3) and myeloid-derived suppressor cell-mediated immune suppressors (Arg1) were attenuated by decursin., Conclusion: Our results suggest that decursin is a novel HIF-1α inhibitor that functions by promoting its proteasomal degradation and that it also helps improve T cell activation in tumour microenvironment; these findings provide new explanations about its anti-cancer and anti-angiogenic activity mechanisms., Competing Interests: Declaration of Competing Interest The authors have no conflicts of interest to declare., (Copyright © 2020 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

As a common feature in a majority of malignant tumors, hypoxia has become the Achilles' heel of photodynamic therapy (PDT). The development of type-I photosensitizers that show hypoxia-tolerant PDT efficiency provides a straightforward way to address this issue. However, type-I PDT materials have rarely been discovered. Herein, a π-conjugated molecule with A-D-A configuration, COi6-4Cl, is reported. The H 2 O-dispersible nanoparticle of COi6-4Cl can be activated by an 880 nm laser, and displays hypoxia-tolerant type I/II combined PDT capability, and more notably, a high NIR-II fluorescence with a quantum yield over 5%. Moreover, COi6-4Cl shows a negligible photothermal conversion effect. The non-radiative decay of COi6-4Cl is suppressed in the dispersed and aggregated state due to the restricted molecular vibrations and distinct intermolecular steric hindrance induced by its four bulky side chains. These features make COi6-4Cl a distinguished single-NIR-wavelength-activated phototheranostic material, which performs well in NIR-II fluorescence-guided PDT treatment and shows an enhanced in vivo anti-tumor efficiency over the clinically approved Chlorin e6, by the equal stresses on hypoxia-tolerant anti-tumor therapy and deep-penetration imaging. Therefore, the great potential of COi6-4Cl in precise PDT cancer therapy against hypoxia challenges is demonstrated., (© 2020 Wiley-VCH GmbH.)

Rationale: Vascular abnormality stemming from the hypoxia-driven elevation of proangiogenic factors is a hallmark for many solid malignant tumors, including colorectal cancer (CRC) and its liver metastasis. We report a hypoxia-triggered liposome-supported metal-polyphenol-gene bio-nanoreactor to tune the proangiogenic factor-mediated immunotolerance and synergize the elicited tumoricidal immunity for CRC treatment. Methods: With the aid of polyphenol gallic acid, Cu 2+ ion-based intracellular bio-nanoreactor was synthesized for the delivery of small interfering RNA targeting vascular endothelial growth factor and then cloaked with a hybrid liposomal membrane that harbored a hypoxia-responsive azobenzene derivative. In hypoxic tumor, the liposomal shell disintegrated, and a shrunk-size bio-nanoreactor was burst released. Intracellularly, Cu 2+ from the bio-nanoreactor catalyzed a Fenton-like reaction with glutathione, which efficiently converted H 2 O 2 to •OH and enabled a chemodynamic therapy (CDT) in tumor sites. With the alleviation of proangiogenic factor-mediated immunotolerance and high production of CDT-induced tumor-associated antigens, robust tumoricidal immunity was co-stimulated. Results: With colorectal tumor and its liver metastasis models, we determined the underlying mechanism of proangiogenic factor-mediated immunotolerance and highlighted that the liposomal bio-nanoreactor could create positive feedback among the critical players in the vascular endothelium and synergize the elicited tumoricidal immunity. Conclusion: Our work provides an alternative strategy for exerting efficient tumoricidal immunity in the proangiogenic factor-upregulated subpopulation of CRC patients and may have a wide-ranging impact on cancer immune-anti-angiogenic complementary therapy in clinics., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

A hypoxic microenvironment is a hallmark in different types of tumors; this phenomenon participates in a metabolic alteration that confers resistance to treatments. Because of this, it was proposed that a combination of 2-methoxyestradiol (2-ME) and sodium dichloroacetate (DCA) could reduce this alteration, preventing proliferation through the reactivation of aerobic metabolism in lung adenocarcinoma cell line (A549). A549 cells were cultured in a hypoxic chamber at 1% O 2 for 72 hours to determine the effect of this combination on growth, migration, and expression of hypoxia-inducible factors (HIFs) by immunofluorescence. The effect in the metabolism was evaluated by the determination of glucose/glutamine consumption and the lactate/glutamate production. The treatment of 2-ME (10  μ M) in combination with DCA (40 mM) under hypoxic conditions showed an inhibitory effect on growth and migration. Notably, this reduction could be attributed to 2-ME, while DCA had a predominant effect on metabolic activity. Moreover, this combination decreases the signaling of HIF-3 α and partially HIF-1 α but not HIF-2 α . The results of this study highlight the antitumor activity of the combination of 2-ME 10  μ l/DCA 40 mM, even in hypoxic conditions., Competing Interests: The authors declare that they have no conflict of interests., (Copyright © 2020 Yair Romero et al.)

Biomineralization of biomaterials has shown extraordinary potential in cancer treatment, but the exploration of their in vivo applications is still insufficient. Here, we report a biohybrid microalgae system using a biomineralization approach to improve their biocompatibility, while keeping their living activities for radiation and photodynamic synergistic therapy in breast cancer. The biohybrid algae (Algae@SiO 2 ) synthesized by a one-step biomimetic silicification method could significantly enhance their cytotoxicity and tolerance, improving the living activity in the tumor area. The innate chlorophyll and unique optical property make Algae@SiO 2 possess dual imaging ability, namely, photoacoustic imaging and fluorescence imaging. Algae@SiO 2 accumulated in tumor sites could generate oxygen in situ by external light-mediated photosynthesis, relieve tumor hypoxia, and then enhance the efficiency of radiation therapy. As a natural photosensitizer, the released chlorophyll from Algae@SiO 2 could provide reactive oxygen species to kill the cancer cells for the cascaded photodynamic therapy. The significant suppression of tumor growth in the mice bearing 4T1 tumor successfully demonstrates the promising anti-tumor effect of the Algae@SiO 2 -mediated synergistic therapy. Our results show that biohybrid algae, integrated with PAI/FI dual imaging, radiosensitization, and cascaded photothermal therapy, is a promising multifunctional efficient biosystem for cancer treatment.

Antiangiogenic therapy is widely administered in many cancers, and the antiangiogenic drug sorafenib offers moderate benefits in advanced hepatocellular carcinoma (HCC). However, antiangiogenic therapy can also lead to hypoxia-driven angiogenesis and immunosuppression in the tumor microenvironment (TME) and metastasis. Here, we report the synthesis and evaluation of NanoMnSor, a tumor-targeted, nanoparticle drug carrier that efficiently codelivers oxygen-generating MnO 2 and sorafenib into HCC. We found that MnO 2 not only alleviates hypoxia by catalyzing the decomposition of H 2 O 2 to oxygen but also enhances pH/redox-responsive T1-weighted magnetic resonance imaging and drug-release properties upon decomposition into Mn 2+ ions in the TME. Moreover, macrophages exposed to MnO 2 displayed increased mRNA associated with the immunostimulatory M1 phenotype. We further show that NanoMnSor treatment leads to sorafenib-induced decrease in tumor vascularization and significantly suppresses primary tumor growth and distal metastasis, resulting in improved overall survival in a mouse orthotopic HCC model. Furthermore, NanoMnSor reprograms the immunosuppressive TME by reducing the hypoxia-induced tumor infiltration of tumor-associated macrophages, promoting macrophage polarization toward the immunostimulatory M1 phenotype, and increasing the number of CD8 + cytotoxic T cells in tumors, thereby augmenting the efficacy of anti-PD-1 antibody and whole-cell cancer vaccine immunotherapies. Our study demonstrates the potential of oxygen-generating nanoparticles to deliver antiangiogenic agents, efficiently modulate the hypoxic TME, and overcome hypoxia-driven drug resistance, thereby providing therapeutic benefit in cancer.

Insights into the role of the tumor suppressor pVHL in oxygen sensing motivated the testing of drugs that target the transcription factor HIF or HIF-responsive growth factors, such as VEGF, for the treatment of cancers caused by VHL inactivation, such as clear-cell renal cell carcinoma (ccRCC). Multiple VEGF inhibitors are now approved for the treatment of ccRCC, and a HIF2α inhibitor has advanced to phase 3 development for this disease. These inhibitors are now also increasingly combined with immune-checkpoint blockers. In this Perspective, we describe the understanding of the mechanisms of oxygen sensing and hypoxia signaling that resulted in the development of HIF2α-targeted therapies for patients with VHL-associated tumors. We also present future directions for extending the use of these therapies to other cancers.

The hypoxic microenvironment in solid tumors severely limits the efficacy of photodynamic therapy (PDT). Therefore, the development of nanocarriers co-loaded with photosensitizers and oxygen, together with imaging guidance ability, is of great significance in cancer therapy. However, previously reported synthetic methods for these multi-functional probes are complicated, and the raw materials used are toxic. Methods: Herein, the human endogenous protein, hemoglobin (Hb), was used for the simultaneous biomimetic synthesis of Gd-based nanostructures and co-loading of Chlorine e6 (Ce6) and oxygen for alleviating the hypoxic environment of tumors and accomplishing magnetic resonance imaging (MRI)-guided enhanced PDT. The Gd@Hb Ce6-PEG nanoprobes were synthesized via a green and protein biomimetic approach. The physicochemical properties, including relaxivity, oxygen-carrying/release capability, and PDT efficacy of Gd@Hb Ce6-PEG , were measured in vitro and in vivo on tumor-bearing mice after intravenous injection. Morphologic and functional MRI were carried out to evaluate the efficacy of PDT. Results: The results demonstrated the successful synthesis of compact Gd@Hb Ce6-PEG nanostructures with desired multi-functionalities. Following treatment with the nanoparticles, the embedded MR moiety was effective in lighting tumor lesions and guiding therapy. The oxygen-carrying capability of Hb after biomimetic synthesis was confirmed by spectroscopic analysis and oxygen detector in vitro . Further, tumor oxygenation for alleviating tumor hypoxia in vivo after intravenous injection of Gd@Hb Ce6-PEG was verified by photoacoustic imaging and immunofluorescence staining. The potent treatment efficacy of PDT on early-stage was observed by the morphologic and functional MR imaging. Importantly, rapid renal clearance of the particles was observed after treatment. Conclusion: In this study, by using a human endogenous protein, we demonstrated the biomimetic synthesis of multi-functional nanoprobes for simultaneous tumor oxygenation and imaging-guided enhanced PDT. The therapeutic efficacy could be quantitatively confirmed at 6 h post PDT with diffusion-weighted imaging (DWI)., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

The overexpression of estrogen receptor (ER) α is not only closely related to the development of ER + breast cancer, but is also an important biomarker for clinical diagnosis and treatment. Herein, we report several ERα targeting hypoxia turn-on fluorescent probes with antitumor activity for breast cancer cells. Among them, probes 3 and 5 displayed good ERα targeting ability and favorable hypoxia turn-on response in MCF-7 cells. Moreover, the probes 3 and 5 exhibited good antiproliferative activity towards MCF-7 cells (IC 50 = 8.5 μM, 10.3 μM) and a much lower cytotoxicity to normal cells compared with the positive control. It is expected that these novel fluorescent probes may provide useful tools for the theranostics of ER + breast cancer.

Tumor hypoxia compromises the therapeutic efficacy of oxygen (O 2 )-dependent treatment methods as the endogenous O 2 levels have an important influence on the production of reaction oxygen species. Herein, a synergistic multifunctional mesoporous Fe@Sn-UCNPs bio-photocatalytic nanoplatform is provided to comprehensively realize endogenous hydrogen peroxide (H 2 O 2 )-activatable, self-supplied O 2 , photothermal performance, and near-infrared-mediated magnetic targeting PDT/PTT simultaneously for relieving tumor hypoxia. Such a nanoplatform is constructed by encapsulating magnetic Fe 3 O 4 with lanthanide-ion-doped mesoporous tin oxide upconversion nanoparticles and further modified with phosphorylated serine and poly(ethylene glycol) for enhancing the biocompatibility and solubility. The nanoparticles can be activated by endogenous H 2 O 2 and in situ generated O 2 to relieve hypoxia through catalytic reaction. Therefore, H 2 O 2 -responsive/O 2 -evolving nanoparticles can elevate the O 2 level in the tumor site for an apparently enhanced PDT effect in vitro and in vivo. What is more, Fe@Sn-UCNPs demonstrate enhanced photothermal conversion efficiency based on the special nanostructure and much more circuit loops for electron transitions between Fe 3 O 4 and Sn-UCNPs, and the electronic structure of Fe@Sn-UCNPs was calculated. In addition, such Fe@Sn-UCNPs also exhibit multimodality imaging performance (including photothermal, magnetic resonance, and computed tomography imaging) for monitoring and tracking the in vivo tumor therapeutic process. This work provides novel insight into the smart Fe@Sn-UCNPs as an "all-in-one" theranostic nanosystem for cancer therapy.

A family of five heteroleptic complexes [Ru(C^N)(N^N) 2 ][PF 6 ] (HC^N = methyl 1-butyl-2-arylbenzimidazolecarboxylate; N^N = polypyridine) has been synthesized to act as biologically-compatible green light photosensitizers (PSs) with phototherapeutic indexes (PIs) up to higher than 700 under hypoxia (2% O 2 ) in HeLa cancer cells under short time of irradiation.

Development of targeted therapies for triple-negative breast cancer (TNBC) is an unmet medical need. Cisplatin has demonstrated its promising potential for the treatment of TNBC in clinical trials; however, cisplatin treatment is associated with hypoxia that, in turn, promotes cancer stem cell (CSC) enrichment and drug resistance. Therapeutic approaches to attenuate this may lead to increased cisplatin efficacy in the clinic for the treatment of TNBC. In this report we analyzed clinical datasets of TNBC and found that TNBC patients possessed higher levels of EGFR and hypoxia gene expression. A similar expression pattern was also observed in cisplatin-resistant ovarian cancer cells. We, thus, developed a new therapeutic approach to inhibit EGFR and hypoxia by combination treatment with metformin and gefitinib that sensitized TNBC cells to cisplatin and led to the inhibition of both CD44+/CD24- and ALDH+ CSCs. We demonstrated a similar inhibition efficacy on organotypic cultures of TNBC patient samples ex vivo. Since these drugs have already been used frequently in the clinic; this study illustrates a novel, clinically translatable therapeutic approach to treat patients with TNBC.

The high reactive oxygen species (ROS) generation ability and simple construction of sonosensitizer systems remain challenging in sonodynamic therapy against the hypoxic tumor. In this work, we rationally prepared MOF-derived double-layer hollow manganese silicate nanoparticle (DHMS) with highly effective ROS yield under ultrasound irradiation for multimodal imaging-guided sonodynamic therapy (SDT). The presence of Mn in DHMS increased ROS generation efficiency because it could be oxidized by holes to improve the electron-hole separation. Moreover, DHMS could produce oxygen in the tumor microenvironment, which helps overcome the hypoxia of the solid tumor and thus enhance the treatment efficiency. In vivo experiments demonstrated efficient tumor inhibition in DHMS-mediated SDT guided by ultrasound and magnetic resonance imaging. This work presents a MOF-derived nanoparticle with sonosensitive and oxygen generating ability, which provides a promising strategy for tumor hypoxia in SDT., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The anti-hypoxia-A2-Adenosinergic immunotherapies of cancer emerged as the only available now approach to enable the tumor rejection in those progressing cancer patients that are refractory to all other current treatments. Several different classes of drugs are offered to inhibit the Hypoxia-HIF-1alpha-mediated and extracellular adenosine-A2A adenosine receptor-mediated immunosuppressive signaling in tumor microenvironment. It is suggested that the most promising treatments must include the blockade of cAMP-elevating A2A adenosine receptors and the elimination of hypoxia in tumors by oxygenation agents and hyperoxic breathing. The observations in ongoing clinical trials support this conclusion., (Copyright © 2020. Published by Elsevier Ltd.)

Solid tumors have abnormal microcirculation that limits oxygen delivery and leads to a hypoxic tumor microenvironment. Tumor hypoxia stabilizes the transcription factor HIF-1α that can trigger immunosuppression through A2A adenosine receptors which prevents immune attack on tumors. In addition, success of chemotherapy and radiation therapy appears to be dependent on oxygen levels. Two main pharmaceutical classes of agents (hemoglobin based and perfluorocarbon man-made carbon oils) have been tested in tumor models as enhanced oxygen therapeutics. This article will review how these agents function as well as examine work to date with both drug classes., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Hypoxia is a major impediment to many foremost cancer treatments that require O 2 for generation of tumoricidal reactive oxygen species. Liquid perfluorocarbons (PFCs) are inert gas solvents that help alleviate this oxygen deficit situation. PFC nanoemulsions have demonstrated oxygen delivery to tissues. The lifetime of 1 O 2 in PFCs is considerably expanded. PFC nanodroplets extravasate and accumulate in tumors. Alternatively, PFCs stabilize injectable O 2 microbubbles. On-demand local O 2 delivery is facilitated by ultrasound. Liquid PFC nanodroplets that convert into microbubbles upon activation provide another shuttle for O 2 -delivery. PFC nanocarriers can also be enriched with fluorescent dyes, radiopaque materials, photo(sono)sensitizers, loaded with chemotherapeutics, and fitted with targeting devices, or stimuli-responsive functions for image-guided theranostics. We review recent literature on PFC-based O 2 carriers to enhance the efficacy of radiotherapy, photo(sono)dynamic therapy and chemotherapy. Of particular relevance to this series of reviews, PFC-based carriers may provide novel strategies to promote T-cell trafficking into tumors to improve immune responses., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Purpose: Radiotherapy (RT) is one of the major treatments of cervical cancer. Although the prognosis of clinical cervical cancer becomes better in recent years, some patients still suffer from the recurrence and metastasis. Insufficiency of glucose and oxygen supply could increase the radioresistance of cervical cancer cells through regulating hypoxia-inducible factor 1 (HIF-1) in tumor microenvironment and glucose metabolism. And, berberine can regulate HIF-1. However, how berberine regulates tumor microenvironment and radioresistance through HIF-1 remains to be elucidated. Materials and methods: The human HeLa cervical cancer cells were treated with berberine and radiation under the high and low concentrations of glucose and oxygen, respectively. The survival of cells was tested by CCK-8 assay and colony formation assay. We investigated the PI3K- and IDH3α-related pathway molecules that may regulate HIF-1α by qPCR and western blot. Differentially expressed genes (DEGs) were identified by integrating five related cohort profile datasets. Protein-protein interaction (PPI) network analyses of DEGs related to HIF-1α were conducted by using the STRING database and Cytoscape software. Results: Berberine dramatically damaged HeLa cells under hypoxic and low-glucose conditions compared with the normoxic and high-glucose conditions. The clonogenic assay indicated that the application of berberine decreased the number of colony counts compared to the negative control. Low doses of berberine might decrease the level of phospho-PI3K and HIF-1α under the nutrient-deprived conditions. Moreover, we found that most of the differentially expressed genes which were related to CDKN1B were the downstream molecules regulated by HIF-1α. Conclusion: The results indicated that berberine could dramatically overcome the low-glucose and hypoxia-induced radioresistance. And the regulation berberine on nutrition-deficient conditions might involve in PI3K/HIF-1 pathway. Thus, the interference of glucose metabolism by berberine might be an attractive method to eliminate radioresistant cells and improve radiotherapy efficacy.

Hypoxia in tumor microenvironment is responsible for resistance to conventional modes of cancer therapeutics. A manganese-clay hybrid compound MHC was shown to generate molecular oxygen in aqueous solution. In this study we have shown that MHC, in hypoxia, causes cancer cell death, through release of molecular oxygen and via p53-dependent apoptosis. MHC treatment of cells results in depletion of mitochondrial membrane potential and inhibition of ROS production, in a cell-specific manner. In hypoxia, the oxygen from MHC releases cells from S-phase arrest thus causing p53-dependent apoptosis. The induction of apoptosis by MHC is higher in p53 Wt/Wt cells when it is compared with p53 Mt/Mt cells. The released oxygen from MHC triggers apoptosis via p53 activation through its enhanced homo-oligomerization, post-translational modifications and nuclear localization. Thus MHC as a cellular oxygen-releasing compound has high potential as a drug for hypoxic tumor regression., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

We have previously demonstrated that endothelial targeting of gold nanoparticles followed by external beam irradiation can cause specific tumor vascular disruption in mouse models of cancer. The induced vascular damage may lead to changes in tumor physiology, including tumor hypoxia, thereby compromising future therapeutic interventions. In this study, we investigate the dynamic changes in tumor hypoxia mediated by targeted gold nanoparticles and clinical radiation therapy (RT). By using noninvasive whole-body fluorescence imaging, tumor hypoxia was measured at baseline, on day 2 and day 13, post-tumor vascular disruption. A 2.5-fold increase (P<0.05) in tumor hypoxia was measured two days after combined therapy, resolving by day 13. In addition, the combination of vascular-targeted gold nanoparticles and radiation therapy resulted in a significant (P<0.05) suppression of tumor growth. This is the first study to demonstrate the tumor hypoxic physiological response and recovery after delivery of vascular-targeted gold nanoparticles followed by clinical radiation therapy in a human non-small cell lung cancer athymic Foxn1nu mouse model., Competing Interests: The authors have declared that no competing interests exist.

Tumor-associated hypoxia influences the radiation response of head-and-neck cancer (HNSCC) patients, and a lack of early hypoxia resolution during treatment considerably deteriorates outcomes. As the detrimental effects of hypoxia are partly related to the induction of an immunosuppressive microenvironment, we investigated the interaction between tumor hypoxia dynamics and the PD-1/PD-L1 axis in HNSCC patients undergoing chemoradiation and its relevance for patient outcomes in a prospective trial. Methods: 49 patients treated with definitive chemoradiation for locally advanced HNSCC were enrolled in this trial and received longitudinal hypoxia PET imaging using fluorine-18 misonidazole ([ 18 F]FMISO) at weeks 0, 2 and 5 during treatment. Pre-therapeutic tumor biopsies were immunohistochemically analyzed regarding the PD-1/PD-L1 expression both on immune cells and on tumor cells, and potential correlations between the PD-1/PD-L1 axis and tumor hypoxia dynamics during chemoradiation were assessed using Spearman's rank correlations. Hypoxia dynamics during treatment were quantified by subtracting the standardized uptake value (SUV) index at baseline from the SUV values at weeks 2 or 5, whereby SUV index was defined as ratio of maximum tumor [ 18 F]FMISO SUV to mean SUV in the contralateral sternocleidomastoid muscle ( i.e. tumor-to-muscle ratio). The impact of the PD-1/PD-L1 expression alone and in combination with persistent tumor hypoxia on locoregional control (LRC), progression-free survival (PFS) and overall survival (OS) was examined using log-rank tests and Cox proportional hazards models. Results: Neither PD-L1 nor PD-1 expression levels on tumor-infiltrating immune cells influenced LRC (HR = 0.734; p = 0.480 for PD-L1, HR = 0.991; p = 0.989 for PD-1), PFS (HR = 0.813; p = 0.597 for PD-L1, HR = 0.796; p = 0.713 for PD-1) or OS (HR = 0.698; p = 0.405 for PD-L1, HR = 0.315; p = 0.265 for PD-1). However, patients with no hypoxia resolution between weeks 0 and 2 and PD-L1 expression on tumor cells, quantified by a tumor proportional score (TPS) of at least 1%, showed significantly worse LRC (HR = 3.374, p = 0.022) and a trend towards reduced PFS (HR = 2.752, p = 0.052). In the multivariate Cox regression analysis, the combination of absent tumor hypoxia resolution and high tumoral PD-L1 expression remained a significant prognosticator for impaired LRC (HR = 3.374, p = 0.022). On the other side, tumoral PD-L1 expression did not compromise the outcomes of patients whose tumor-associated hypoxia declined between week 0 and 2 during chemoradiation (LRC: HR = 1.186, p = 0.772, PFS: HR = 0.846, p = 0.766). Conclusion: In this exploratory analysis, we showed for the first time that patients with both persistent tumor-associated hypoxia during treatment and PD-L1 expression on tumor cells exhibited a worse outcome, while the tumor cells' PD-L1 expression did not influence the outcomes of patients with early tumor hypoxia resolution. While the results have to be validated in an independent cohort, these findings form a foundation to investigate the combination of hypoxic modification and immune checkpoint inhibitors for the unfavorable subgroup, moving forward towards personalized radiation oncology treatment., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Photodynamic therapy (PDT) is a promising strategy in cancer treatment that utilizes photosensitizers (PSs) to produce reactive oxygen species (ROS) and eliminate cancer cells under specific wavelength light irradiation. However, special tumor environments, such as those with overexpression of glutathione (GSH), which will consume PDT-mediated ROS, as well as hypoxia in the tumor microenvironment (TME) could lead to ineffective treatment. Moreover, PDT is highly light-dependent and therefore can be hindered in deep tumor cells where light cannot easily penetrate. To solve these problems, we designed oxygen-dual-generating nanosystems MnO 2 @Chitosan-CyI (MCC) for enhanced phototherapy. Methods : The TME-sensitive nanosystems MCC were easily prepared through the self-assembly of iodinated indocyanine green (ICG) derivative CyI and chitosan, after which the MnO 2 nanoparticles were formed as a shell by electrostatic interaction and Mn-N coordinate bonding. Results : When subjected to NIR irradiation, MCC offered enhanced ROS production and heat generation. Furthermore, once endocytosed, MnO 2 could not only decrease the level of GSH but also serve as a highly efficient in situ oxygen generator. Meanwhile, heat generation-induced temperature increase accelerated in vivo blood flow, which effectively relieved the environmental tumor hypoxia. Furthermore, enhanced PDT triggered an acute immune response, leading to NIR-guided, synergistic PDT/photothermal/immunotherapy capable of eliminating tumors and reducing tumor metastasis. Conclusion: The proposed novel nanosystems represent an important advance in altering TME for improved clinical PDT efficacy, as well as their potential as effective theranostic agents in cancer treatment., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Rationale: Nanoscale vehicles responsive to abnormal variation in tumor environment are promising for use in targeted delivery of therapeutic drugs specifically to tumor sites. Herein, we report the design and fabrication of self-accelerating H 2 O 2 -responsive plasmonic gold nanovesicles (GVs) encapsulated with tirapazamine (TPZ) and glucose oxidase (GOx) for synergistic chemo/starving therapy of cancers. Methods: Gold nanoparticles were modified with H 2 O 2 -responsive amphiphilic block copolymer PEG 45 - b -PABE 330 by ligand exchange. The TPZ and GOx loaded GVs (TG-GVs) were prepared through the self-assembly of PEG 45 - b -PABE 330 -grafted nanoparticles together with TPZ and GOx by solvent displacement method. Results: In response to H 2 O 2 in tumor, the TG-GVs dissociate to release the payloads that are, otherwise, retained inside the vesicles for days without noticeable leakage. The released GOx enzymes catalyze the oxidation of glucose by oxygen in the tumor tissue to enhance the degree of hypoxia that subsequently triggers the reduction of hypoxia-activated pro-drug TPZ into highly toxic free radicals. The H 2 O 2 generated in the GOx-catalyzed reaction also accelerate the dissociation of vesicles and hence the release rate of the cargoes in tumors. The drug-loaded GVs exhibit superior tumor inhibition efficacy in 4T1 tumor-bearing mice owing to the synergistic effect of chemo/starvation therapy, in addition to their use as contrast agents for computed tomography imaging of tumors. Conclusion: This nanoplatform may find application in managing tumors deeply trapped in viscera or other important tissues that are not compatible with external stimulus (e.g. light)., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Electrochemotherapy (ECT), the combination of electric pulses (EPs) and an anticancer drug, is a type of cancer treatment method. We investigated the effect of 217-Hz magnetic fields (MFs) similar to that generated by GSM900 mobile phones, as intervening factors, on proposed mechanisms of ECT including permeability, tumor hypoxia and immune system response. The 4T1 cells were exposed to extremely low-frequency (ELF)-MFs at 93, 120 or 159 µT intensities, generated by Helmholtz coils 10 min, and then put in individual groups, comprising no treatment, chemotherapy, EPs or ECT. The cell viability was evaluated. Then, two treatment protocols were selected for in vivo experiments. The mice with 4T1 tumor cells were exposed to ELF-MFs 10 min/day until the day their tumors reached 8 mm in diameter. Then, the tumors were treated to ECT. Tumor hypoxia and immune system response were analyzed through immunohistochemistry assay and enzyme-linked immunosorbent assay technique, respectively. The results in vitro indicated a significant decreased ECT efficacy of 60 V/cm, 5 kHz at the flux density of 93 µT. The results in vivo showed that pre-exposure to ELF-MFs could increase tumor hypoxia induced by ECT. In addition, exposure to ELF-MFs before ECT caused a significant increase in interferon-γ/interleukin-4 in comparison with ECT alone. More studies, including studies on the effect of ELF-MFs emitted from mobile phones on tumor volume changes induced by ECT, are needed to elucidate how the process of ECT is influenced by the MFs.

Enhanced drug delivery can improve the therapeutic efficacy of drugs and help overcome side effects. However, many reported drug-delivery systems are too complex and irreproducible for practical use. In this work, the design of a hypoxia-responsive molecular container based on calixarene, called CAC4A, which presents a significant advance in practical, hypoxia-targeted drug-delivery, is reported. CAC4A enables a wide variety of clinical drugs to be quantitatively loaded to improve their solubility and stability, as well as enable the administration of reduced doses. Furthermore, as a result of its azo functional groups, which are sensitive to reduction within a hypoxic environment, it is possible to achieve tumor-targeted drug-release with reduced side effects. CAC4A fulfils all essential requirements for a drug-delivery system in addition to multiple advantages, including facile preparation, well-defined molecular weight, and structure, and universal applicability. Such features collectively enable supramolecular prodrugs to be formulated simply and reproducibly, with potential for bench-to-bedside translation. Moreover, CAC4A is amenable to other therapy modalities and can be facilely decorated with functional groups and hybridized with nanomaterials, providing ample possibilities for its role in future drug-delivery systems., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: Emerging biomarkers from medical imaging or molecular characterization of tumour biopsies open up for combining the two and exploiting their synergy in treatment planning of cancer patients. We generated a paired data set of imaging- and gene-based hypoxia biomarkers in cervical cancer, appraised the influence of intratumour heterogeneity in patient classification, and investigated the benefit of combining the methodologies in prediction of chemoradiotherapy failure., Methods: Hypoxic fraction from dynamic contrast enhanced (DCE)-MR images and an expression signature of six hypoxia-responsive genes were assessed as imaging- and gene-based biomarker, respectively in 118 patients., Findings: Dichotomous biomarker cutoff to yield similar hypoxia status by imaging and genes was defined in 41 patients, and the association was validated in the remaining 77 patients. The two biomarkers classified 75% of 118 patients with the same hypoxia status, and inconsistent classification was not related to imaging-defined intratumour heterogeneity in hypoxia. Gene-based hypoxia was independent on tumour cell fraction in the biopsies and showed minor heterogeneity across multiple samples in 9 tumours. Combining imaging- and gene-based classification gave a significantly better prediction of PFS than one biomarker alone. A combined dichotomous biomarker optimized in 77 patients showed a large separation in PFS between more and less hypoxic tumours, and separated the remaining 41 patients with different PFS. The combined biomarker showed prognostic value together with tumour stage in multivariate analysis., Interpretation: Combining imaging- and gene-based biomarkers may enable more precise and informative assessment of hypoxia-related chemoradiotherapy resistance in cervical cancer., Funding: Norwegian Cancer Society, South-Eastern Norway Regional Health Authority, and Norwegian Research Council., Competing Interests: Declaration of Competing Interest HL is registered as inventor of a patent application covering the clinical use of the hypoxia gene signature (WO2013/124,738)., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)