The impact of O2 availability on human cancer

Nanoparticle-Based Activatable Probes for Bioimaging

Molecular imaging can provide functional and molecular information at the cellular or subcellular level in vivo in a noninvasive manner. Activatable nanoprobes that can react to the surrounding physiological environment or biomarkers are appealing agents to improve the efficacy, specificity, and sensitivity of molecular imaging. The physiological parameters, including redox status, pH, presence of enzymes, and hypoxia, can be designed as the stimuli of the activatable probes. However, the success rate of imaging nanoprobes for clinical translation is low. Herein, the recent advances in nanoparticle-based activatable imaging probes are critically reviewed. In addition, the challenges for clinical translation of these nanoprobes are also discussed in this review.

Non-Hodgkin Lymphoma Metabolism

Non-Hodgkin lymphomas (NHLs) are a heterogeneous group of lymphoid neoplasms with different biological characteristics. About 90% of all lymphomas in the United States originate from B lymphocytes, while the remaining originate from T cells [1]. The treatment of NHLs depends on the neoplastic histology and stage of the tumor, which will indicate whether radiotherapy, chemotherapy, or a combination is the best suitable treatment [2]. The American Cancer Society describes the staging of lymphoma as follows: Stage I is lymphoma in a single node or area. Stage II is when that lymphoma has spread to another node or organ tissue. Stage III is when it has spread to lymph nodes on two sides of the diaphragm. Stage IV is when cancer has significantly spread to organs outside the lymph system. Radiation therapy is the traditional therapeutic route for localized follicular and mucosa-associated lymphomas. Chemotherapy is utilized for the treatment of large-cell lymphomas and high-grade lymphomas [2]. However, the treatment of indolent lymphomas remains problematic as the patients often have metastasis, for which no standard approach exists [2].

Boosting Nanomedicine Efficacy with Hyperbaric Oxygen Therapy

Nanomedicine has been a hot topic in the field of tumor therapy in the past few decades. Because of the enhanced permeability and retention effect (EPR effect), nanomedicine can passively yet selectively accumulate at tumor tissues. As a result, it can improve drug concentration in tumor tissues and reduce drug distribution in normal tissues, thereby contributing to enhanced antitumor effect and reduced adverse effects. However, the therapeutic efficacy of anticancer nanomedicine is not satisfactory in clinical settings. Therefore, how to improve the clinical therapeutic effect of nanomedicine has become an urgent problem. The grand challenges of nanomedicine lie in how to overcome various pathophysiological barriers and simultaneously kill cancer cells effectively in hypoxic tumor microenvironment (TME). To this end, the development of novel stimuli-responsive nanomedicine has become a new research hotspot. While a great deal of progress has been made in this direction and preclinical results report many different kinds of promising multifunctional smart nanomedicine, the design of these intelligent nanomedicines is often too complicated, the requirements for the preparation processes are strict, the cost is high, and the clinical translation is difficult. Thus, it is more practical to find solutions to promote the therapeutic efficacy of commercialized nanomedicines, for example, Doxil^®, Oncaspar^®, DaunoXome^®, Abraxane^®, to name a few. Increasing attention has been paid to the combination of modern advanced medical technology and nanomedicine for the treatment of various malignancies. Recently, we found that hyperbaric oxygen (HBO) therapy could enhance Doxil^® antitumor efficacy. Inspired by this study, we further carried out researches on the combination of HBO therapy with other nanomedicines for various cancer therapies, and revealed that HBO therapy could significantly boost antitumor efficacy of nanomedicine-mediated photodynamic therapy and photothermal therapy in different kinds of tumors, including hepatocellular carcinoma, breast cancer, and gliomas. Our results implicate that HBO therapy might be a universal strategy to boost therapeutic efficacy of nanomedicine against hypoxic solid malignancies.

Immune remodeling triggered by photothermal therapy with semiconducting polymer nanoparticles in combination with chemotherapy to inhibit metastatic cancers

Immune remodeling was triggered by photothermal therapy based on semiconducting polymer nanoparticles in combination with chemotherapy based on a hypoxia-activated antitumor drug (tirapazamine) to efficiently inhibit metastatic tumors.

TRIB3 Promotes Lung Adenocarcinoma Progression via an Enhanced Warburg Effect

Background

The pseudokinase Tribbles 3 (TRIB3) is involved in many cellular processes and various cancers. In recent years, the importance of metabolic transformation in the maintenance of malignant tumors has become increasingly prominent. Abnormal metabolism of cancer cells is considered a hallmark of cancer. However, the exact role and molecular mechanism of TRIB3 in lung adenocarcinoma (LUAD) cell reprogramming is largely unknown.

Methods

The oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) of cells were examined with a Seahorse XF Extracellular Flux Analyzer. In vitro and in vivo RT-qPCR, Western blotting, and functional assays were performed to explore the functional roles of TRIB3 in LUAD.

Results

In the present study, we demonstrated that TRIB3 is remarkably upregulated in LUAD cell lines as well as tissues. TRIB3 knockdown significantly inhibited LUAD cell growth and suppressed LUAD cell invasion, while TRIB3 overexpression conferred the opposite effects. Moreover, silencing TRIB3 suppressed the tumorigenesis and metastatic ability of LUAD cells. Mechanistically, we demonstrated that silencing TRIB3 significantly impaired aerobic glycolysis ability in LUAD cells. Furthermore, our data indicated that TRIB3 knockdown decreased hypoxia-inducible factor (HIF)1α levels and targeted the glycolytic genes regulated by HIF1α.

Conclusion

Together, our findings revealed a previously unappreciated function of TRIB3 in cancer cell metabolism and tumor progression, illustrating that TRIB3 could be considered a valuable therapeutic target for LUAD patients.

Long Noncoding RNA MIR210HG Promotes the Warburg Effect and Tumor Growth by Enhancing HIF-1α Translation in Triple-Negative Breast Cancer

Background

Hypoxia is an important environmental factor and has been correlated with tumor progression, treatment resistance and poor prognosis in many solid tumors, including triple-negative breast cancer (TNBC). Emerging evidence suggests that long noncoding RNA (lncRNA) functions as a critical regulator in tumor biology. However, little is known about the link between hypoxia and lncRNAs in TNBC.

Methods

TNBC molecular profiles from The Cancer Genome Atlas (TCGA) were leveraged to identify hypoxia-related molecular alterations. Loss-of-function studies were performed to determine the regulatory role of MIR210HG in tumor glycolysis. The potential functions and mechanisms of hypoxia-MIR210HG axis were explored using qPCR, Western blotting, luciferase reporter assay, and polysome profiling.

Results

We found that MIR210HG is a hypoxia-induced lncRNA in TNBC. Loss-of-function studies revealed that MIR210HG promoted the Warburg effect as demonstrated by glucose uptake, lactate production and expression of glycolytic components. Mechanistically, MIR210HG potentiated the metabolic transcription factor hypoxia-inducible factor 1α (HIF-1α) translation via directly binding to the 5'-UTR of HIF-1α mRNA, leading to increased HIF-1a protein level, thereby upregulating expression of glycolytic enzymes. MIR210HG knockdown in TNBC cells reduced their glycolytic metabolism and abolished their tumorigenic potential, indicating the glycolysis-dependent oncogenic activity of MIR210HG in TNBC. Moreover, MIR210HG was highly expressed in breast cancer and predicted poor clinical outcome.

Conclusion

Our results decipher a positive feedback loop between hypoxia and MIR210HG that drive the Warburg effect and suggest that MIR210HG may be a good prognostic marker and therapeutic target for TNBC patients.

HIF and COX-2 expression in triple negative breast cancer cells with hypoxia and 5-fluorouracil

Our purpose was to understand the effects of normoxia or hypoxia on 5-fluorouracil (5-FU) treatment in triple negative breast cancer (TNBC) cells, and characterize the molecular changes in hypoxia inducible factors (HIFs) and cyclooxygenase-2 (COX-2) following treatment. Cell viability and protein levels of HIFs and COX-2 were determined after wild type and HIF silenced MDA-MB-231 cells, and wild type SUM-149 cells, were treated with 5-FU under normoxia or hypoxia. 5-FU reduced cell viability to the same levels irrespective of normoxia or hypoxia. HIF silenced MDA-MB-231 cells showed comparable changes in cell viability, supporting observations that hypoxia and the HIF pathways did not significantly influence cell viability reduction by 5-FU. Our data suggest that HIF-2α accumulation may predispose cancer cells to cell death under hypoxia. SUM-149 cells that have higher COX-2 and HIF-2α following 24 h of hypoxia, were more sensitive to 96 h of hypoxia compared to MDA-MB-231 cells, and were more sensitive to 5-FU than MDA-MB-231 cells. COX-2 levels changed with hypoxia and with 5-FU treatment but patterns were different between the two cell lines. At 96 h, COX-2 increased in both untreated and 5-FU treated cells under hypoxia in MDA-MB-231 cells. In SUM-149 cells, only treatment with 5-FU increased COX-2 at 96 h of hypoxia. Cells that survive hypoxia and 5-FU treatment may exhibit a more aggressive phenotype. Our results support understanding interactions between HIF and COX-2 with chemotherapeutic agents under normoxia and hypoxia, and investigating the use of COX-2 inhibitors in these settings.

Role of Regular Physical Exercise in Tumor Vasculature: Favorable Modulator of Tumor Milieu

The tumor vessel network has been investigated as a precursor of an inhospitable tumor microenvironment, including its repercussions in tumor perfusion, oxygenation, interstitial fluid pressure, pH, and immune response. Dysfunctional tumor vasculature leads to the extravasation of blood to the interstitial space, hindering proper perfusion and causing interstitial hypertension. Consequently, the inadequate delivery of oxygen and clearance of by-products of metabolism promote the development of intratumoral hypoxia and acidification, hampering the action of immune cells and resulting in more aggressive tumors. Thus, pharmacological strategies targeting tumor vasculature were developed, but the overall outcome was not satisfactory due to its transient nature and the higher risk of hypoxia and metastasis. Therefore, physical exercise emerged as a potential favorable modulator of tumor vasculature, improving intratumoral vascularization and perfusion. Indeed, it seems that regular exercise practice is associated with lasting tumor vascular maturity, reduced vascular resistance, and increased vascular conductance. Higher vascular conductance reduces intratumoral hypoxia and increases the accessibility of circulating immune cells to the tumor milieu, inhibiting tumor development and improving cancer treatment. The present paper describes the implications of abnormal vasculature on the tumor microenvironment and the underlying mechanisms promoted by regular physical exercise for the re-establishment of more physiological tumor vasculature.

Novel insights into the role of Clostridium novyi-NT related combination bacteriolytic therapy in solid tumors

Several solid tumors (for example leiomyosarcoma, melanoma and hepatocellular carcinoma) possess areas of hypoxia, which underlies one of the primary reasons of failure of conventional anticancer therapies. The areas of poor vascularization are insensitive to radiotherapy and chemotherapeutic drugs. Conversely, the hypoxic regions of tumors provide an ideal environment for anaerobic bacteria. The attenuated anaerobic bacterium, Clostridium novyi-NT (C. novyi-NT), is highly sensitive to oxygen and can target the destruction of hypoxic and necrotic areas of tumors, inducing oncolysis and characteristics indicative of an immune response. Theoretically, chemotherapy, radiotherapy and immunotherapy combined with bacterial therapy can be used as a novel means of treating solid tumors, promoting tumor regression and inhibiting metastasis formation with a notable beneficial effect. The present review discusses the molecular mechanisms of combined bacteriolytic therapy, predominantly focusing on C. novyi-NT, and summarizes the findings of previous studies on experimental animal models, including its efficacy and safety via different drug delivery routes. This strategy has great potential to overcome the limitations of conventional cancer therapy, resulting in improved treatments, and thus potentially improved outcomes for patients.

Hypoxia-mediated drug resistance in breast cancers

Tissue hypoxia in solid tumors is caused by several pathological changes associated with tumor growth, including altered microvasculature structure, increased diffusional distances, and tumor-associated anemia. As the oxygen tension decreases, tumor cells adapt to the limited oxygen supply. Previous studies have shown that such adaptation leads to an aggressive phenotype that is resistant to many anti-cancer therapies. Induction of hypoxia inducible factors (HIFs) mediates many proteomic and genomic changes associated with tumor hypoxia. In breast cancers, HIFs not only predict poor prognosis, but also promote metastasis and drug resistance. Several studies have proposed HIF-1α as a druggable target in drug-resistant breast cancers, leading to the synthesis and development of small molecule inhibitors. Disappointingly, however, none of these small molecule inhibitors have progressed to clinical use. In this review, we briefly discuss the role of HIF-1α in breast cancer drug resistance and summarize the current and future approaches to targeting this transcription factor in breast cancer treatment.

Glycometabolic rearrangements--aerobic glycolysis in pancreatic cancer: causes, characteristics and clinical applications

Pancreatic cancer is one of the most malignant tumors worldwide, and pancreatic ductal adenocarcinoma is the most common type. In pancreatic cancer, glycolysis is the primary way energy is produced to maintain the proliferation, invasion, migration, and metastasis of cancer cells, even under normoxia. However, the potential molecular mechanism is still unknown. From this perspective, this review mainly aimed to summarize the current reasonable interpretation of aerobic glycolysis in pancreatic cancer and some of the newest methods for the detection and treatment of pancreatic cancer. More specifically, we reported some biochemical parameters, such as newly developed enzymes and transporters, and further explored their potential as diagnostic biomarkers and therapeutic targets.

Association between continuous decrease of plasma VEGF-A levels and the efficacy of chemotherapy in combination with anti-programmed cell death 1 antibody in non-small cell lung cancer patients

OBJECTIVES

Vascular endothelial growth factor-A (VEGF-A) plays important roles in tumor immune suppression and thus correlates with the efficacy of anti-programmed cell death-1/ligand 1 (anti-PD-1/PD-L1) antibodies. We aimed to determine the association between change in plasma VEGF-A levels and the efficacy of chemotherapy combined with anti-PD-1/PD-L1 antibodies (chemo-PD1) in non-small cell lung cancer (NSCLC) patients.

METHODS

We included NSCLC patients treated with chemo-PD1. Plasma VEGF-A levels were measured at baseline (Pre) and days 7 (D7) and 14 (D14) after the initiation of chemo-PD1. Continuous VEGF-A decrease was determined by comparing Pre with the median value of maximum change rate of posttreatment VEGF-A as cutoff. Patients whose change rates of VEGF-A at both D7 and D14 were consistently lower than the cutoff value were classified into the VEGF-A decrease group, whereas those whose VEGF-A at D7 or D14 were higher than the cutoff level were classified into the VEGF-A no-decrease group. The primary outcome was progression-free survival (PFS).

RESULTS

A total of 32 patients were evaluated. The median Pre VEGF-A levels was 49 (range, 13-257). The median change rate of VEGF-A at D7 and D14 was -25.6% (range, -77.5-376.9) and -42.3% (range, -100-138.5) respectively. The cutoff value of posttreatment VEGF-A change rate was -9.3%. The PFS was significantly longer in the VEGF-A decrease group than that in the VEGF-A no-decrease group (median, not reached vs 2.4 months; p = 0.017).

CONCLUSIONS

Continuous decrease of plasma VEGF-A levels during treatment may be associated with the efficacy of chemo-PD1.

PDK4 promotes tumorigenesis and cisplatin resistance in lung adenocarcinoma via transcriptional regulation of EPAS1

The use of cisplatin for the treatment of non-small cell lung cancer has long been constrained by the rapid acquisition of tumor cell chemoresistance. In the present study, we sought to better elucidate the molecular mechanisms underlying this resistance phenotype. To that end, we assessed gene expression patterns in cisplatin-resistant lung adenocarcinoma cells, revealing pyruvate dehydrogenase lipoamide kinase isozyme 4 (PDK4) to be the most up-regulated kinase in resistant cells. We further found PDK4 upregulation to be directly linked with the acquisition of chemoresistance, driving enhanced tumor cell growth in vitro and in vivo. In clinical samples, we also found that PDK4 upregulation was detectable in patients with lung adenocarcinoma and that it was correlated with a poorer prognosis for these patients. From a mechanistic perspective, we further determined that PDK4 was able to promote lung adenocarcinoma cell growth and cisplatin resistance at least in part via regulating endothelial PAS domain-containing protein 1 (EPAS1) expression, thus highlighting PDK4 as a potentially viable therapeutic target in efforts to treat lung adenocarcinoma patients that have become resistant to cisplatin.

Interplay of long non-coding RNAs and HIF-1α: A new dimension to understanding hypoxia-regulated tumor growth and metastasis

Hypoxia is a feature of the solid tumor microenvironment that is associated with poor clinical outcomes in multiple tumor types. Hypoxia-induced factor-1 alpha (HIF-1α) is a master regulator of hypoxic adaption, has been demonstrated to modulate hypoxic gene expression profiling and signaling transduction networks, and is thus a potential therapeutic target. Despite hypoxic response signaling having being extensively studied, the involvement of long non-coding RNAs (lncRNAs) in the hypoxic response has become a new focus of attention. Emerging evidence has documented complex interactions between HIF-1α and lncRNAs, which contribute to the acquisition of multiple hallmarks of cancer. In this review, we focus on recent advances in the study of hypoxia and HIF-1α-regulated lncRNAs, and summarize the molecular mechanisms and functional outcomes of the interplay between lncRNAs and HIF-1α, which may provide important insights into cancer diagnosis and prognosis, enabling better control of cancer.

The Importance of the Tumor Microenvironment and Hypoxia in Delivering a Precision Medicine Approach to Veterinary Oncology

Treating individual patients on the basis of specific factors, such as biomarkers, molecular signatures, phenotypes, environment, and lifestyle is what differentiates the precision medicine initiative from standard treatment regimens. Although precision medicine can be applied to almost any branch of medicine, it is perhaps most easily applied to the field of oncology. Cancer is a heterogeneous disease, meaning that even though patients may be histologically diagnosed with the same cancer type, their tumors may have different molecular characteristics, genetic mutations or tumor microenvironments that can influence prognosis or treatment response. In this review, we describe what methods are currently available to clinicians that allow them to monitor key tumor microenvironmental parameters in a way that could be used to achieve precision medicine for cancer patients. We further describe exciting novel research involving the use of implantable medical devices for precision medicine, including those developed for mapping tumor microenvironment parameters (e.g., O2, pH, and cancer biomarkers), delivering local drug treatments, assessing treatment responses, and monitoring for recurrence and metastasis. Although these research studies have predominantly focused on and were tailored to humans, the results and concepts are equally applicable to veterinary patients. While veterinary clinical studies that have adopted a precision medicine approach are still in their infancy, there have been some exciting success stories. These have included the development of a receptor tyrosine kinase inhibitor for canine mast cell tumors and the production of a PCR assay to monitor the chemotherapeutic response of canine high-grade B-cell lymphomas. Although precision medicine is an exciting area of research, it currently has failed to gain significant translation into human and veterinary healthcare practices. In order to begin to address this issue, there is increasing awareness that cross-disciplinary approaches involving human and veterinary clinicians, engineers and chemists may be needed to help advance precision medicine toward its full integration into human and veterinary clinical practices.

Perfluorocarbon as an adjuvant for tumor anti-angiogenic therapy: Relevance to hypoxia and HIF-1

Lack of vascularization results in increased demand for oxygen and creates a defined feature of the tumor microenvironment known as tumor hypoxia. It is well established that in response to hypoxia, hypoxia-inducible factor-1 α (HIF-1α) is induced which is an important factor in angiogenesis, invasion and metastasis. In turn, HIF-1α regulates the expression of angiogenic factors, such as vascular endothelial growth factor (VEGF). Ascribed to abnormal characteristics of tumor angiogenic networks, antiangiogenic therapy approaches can even worsen the hypoxic condition and can create cancer cells with stemness features. Hence oxygen delivery via perfluorocarbon (PFC) to hypoxic sites seems to result in unstable HIF expression and consequent inactivation of angiogenesis cascade and metastasis and therefore, inhibition of cancer cells stemness.

Tumor-Induced Metabolism and T Cells Located in Tumor Environment

Several subtypes of T cells are located in a tumor environment, each of which supplies their energy using different metabolic mechanisms. Since the cancer cells require high levels of glucose, the conditions of food poverty in the tumor environment can cause inactivation of immune cells, especially the T-effector cells, due to the need for glucose in the early stages of these cells activity. Different signaling pathways, such as PI3K-AKt-mTOR, MAPK, HIF-1α, etc., are activated or inactivated by the amount and type of energy source or oxygen levels that determine the fate of T cells in a cancerous environment. This review describes the metabolites in the tumor environment and their effects on the function of T cells. It also explains the signaling pathway of T cells in the tumor and normal conditions, due to the level of access to available metabolites and subtypes of T cells in the tumor environment.

Phospholipid membrane-decorated deep-penetrated nanocatalase relieve tumor hypoxia to enhance chemo-photodynamic therapy

Hypoxia is a serious impediment to current treatments of many malignant tumors. Catalase, an antioxidant enzyme, is capable of decomposing endogenous hydrogen peroxide (H₂O₂) into oxygen for tumor reoxygenation, but suffered from in vivo instability and limited delivery to deep interior hypoxic regions in tumor. Herein, a deep-penetrated nanocatalase-loading DiIC₁₈ (5, DiD) and soravtansine (Cat@PDS) were provided by coating catalase nanoparticles with PEGylated phospholipids membrane, stimulating the structure and function of erythrocytes to relieve tumor hypoxia for enhanced chemo-photodynamic therapy. After intravenous administration, Cat@PDS preferentially accumulated at tumor sites, flexibly penetrated into the interior regions of tumor mass and remarkably relieved the hypoxic status in tumor. Notably, the Cat@PDS + laser treatment produced striking inhibition of tumor growth and resulted in a 97.2% suppression of lung metastasis. Thus, the phospholipids membrane-coated nanocatalase system represents an encouraging nanoplatform to relieve tumor hypoxia and synergize the chemo-photodynamic cancer therapy.

Abnormal morphology biases hematocrit distribution in tumor vasculature and contributes to heterogeneity in tissue oxygenation

Oxygen heterogeneity in solid tumors is recognized as a limiting factor for therapeutic efficacy. This heterogeneity arises from the abnormal tumor vascular structure. We investigate the role that anomalies in red blood cell transport plays in establishing oxygen heterogeneity in tumor tissue. We introduce a metric to characterize tumor vasculature (mean vessel length-to-diameter ratio, λ) and demonstrate how it predicts tissue-oxygen heterogeneity. We also report an increase in λ following treatment with the antiangiogenic agent DC101. Together, we propose λ as an effective way of monitoring the action of antiangiogenic agents and a proxy measure of oxygen heterogeneity in tumor tissue. Unraveling the causal relationship between tumor vascular structure and tissue oxygenation will pave the way for new personalized therapeutic approaches.

Oxygen heterogeneity in solid tumors is recognized as a limiting factor for therapeutic efficacy. This heterogeneity arises from the abnormal vascular structure of the tumor, but the precise mechanisms linking abnormal structure and compromised oxygen transport are only partially understood. In this paper, we investigate the role that red blood cell (RBC) transport plays in establishing oxygen heterogeneity in tumor tissue. We focus on heterogeneity driven by network effects, which are challenging to observe experimentally due to the reduced fields of view typically considered. Motivated by our findings of abnormal vascular patterns linked to deviations from current RBC transport theory, we calculated average vessel lengths L¯ and diameters d¯ from tumor allografts of three cancer cell lines and observed a substantial reduction in the ratio λ=L¯/d¯ compared to physiological conditions. Mathematical modeling reveals that small values of the ratio λ (i.e., λ<6) can bias hematocrit distribution in tumor vascular networks and drive heterogeneous oxygenation of tumor tissue. Finally, we show an increase in the value of λ in tumor vascular networks following treatment with the antiangiogenic cancer agent DC101. Based on our findings, we propose λ as an effective way of monitoring the efficacy of antiangiogenic agents and as a proxy measure of perfusion and oxygenation in tumor tissue undergoing antiangiogenic treatment.

Carbon Ion Radiobiology

Simple Summary

Radiotherapy with carbon ions has been used for over 20 years in Asia and Europe and is now planned in the USA. The physics advantages of carbon ions compared to X-rays are similar to those of protons, but their radiobiological features are quite distinct and may lead to a breakthrough in the treatment of some cancers characterized by high mortality.

Abstract

Radiotherapy using accelerated charged particles is rapidly growing worldwide. About 85% of the cancer patients receiving particle therapy are irradiated with protons, which have physical advantages compared to X-rays but a similar biological response. In addition to the ballistic advantages, heavy ions present specific radiobiological features that can make them attractive for treating radioresistant, hypoxic tumors. An ideal heavy ion should have lower toxicity in the entrance channel (normal tissue) and be exquisitely effective in the target region (tumor). Carbon ions have been chosen because they represent the best combination in this direction. Normal tissue toxicities and second cancer risk are similar to those observed in conventional radiotherapy. In the target region, they have increased relative biological effectiveness and a reduced oxygen enhancement ratio compared to X-rays. Some radiobiological properties of densely ionizing carbon ions are so distinct from X-rays and protons that they can be considered as a different “drug” in oncology, and may elicit favorable responses such as an increased immune response and reduced angiogenesis and metastatic potential. The radiobiological properties of carbon ions should guide patient selection and treatment protocols to achieve optimal clinical results.

Radio-Sensitizing Effects of CuII and ZnII Complexes of Ornidazole: Role of Nitro Radical Anion

The treatment of malignant cells that are deficient in oxygen due to the insufficient flow of blood is often seen as a major hindrance in radiotherapy. Such cells become radio-resistant because molecular oxygen, the natural and best radio-sensitizer, is depleted. Hence, to compensate this deficiency in oxygen, there is a need for agents that enhance radiation-induced damage of cells (radio-sensitizers) in a manner that normal cells are least affected. Simultaneously, agents capable of showing activity under hypoxic conditions are known as hypoxic cytotoxins that selectively and preferably destroy cells under hypoxic environments. 5-Nitroimidazoles fit both definitions. Their efficiency is based on their ability to generate the nitro radical anion that interacts with the strands of DNA within cells, either damaging or modifying them, leading to cell death. 5-Nitroimidazoles are important radio-pharmaceuticals (radio-sensitizers) in cancer-related treatments where the nitro radical anion has an important role. Since its generation leads to neurotoxic side effects that may be controlled through metal complex formation, this study looks at the possibility of two monomeric complexes of Ornidazole [1-chloro-3-(2-methyl-5-nitro-1H-imidazole-1-yl)propan-2-ol] with Cu^II and Zn^II to be better radio-sensitizers and/or hypoxic cytotoxins than Ornidazole. The study reveals that although there is a decrease in nitro radical anion formation by complexes, such a decrease does not hamper their radio-sensitizing ability. Nucleic acid bases (thymine, cytosine, and adenine) or calf thymus DNA used as targets were irradiated with ⁶⁰Co γ rays either in the absence or presence of Ornidazole and its monomeric complexes. Radiation-induced damage of nucleic acid bases was followed by high-performance liquid chromatography (HPLC), and modification of calf thymus DNA was followed by ethidium bromide fluorescence. Studies indicate that the complexes were better in performance than Ornidazole. Cu^II-ornidazole was significantly better than either Ornidazole or Zn^II-ornidazole, which is attributed to certain special features of the Cu^II complex; aspects like having a stable lower oxidation state enable it to participate in Fenton reactions that actively influence radio-sensitization and the ability of the complex to bind effectively to DNA.

Tumor Microenvironment as a Regulator of Radiation Therapy: New Insights into Stromal-Mediated Radioresistance

Simple Summary

Cancer is multifaceted and consists of more than just a collection of mutated cells. These cancerous cells reside along with other non-mutated cells in an extracellular matrix which together make up the tumor microenvironment or tumor stroma. The composition of the tumor microenvironment plays an integral role in cancer initiation, progression, and response to treatments. In this review, we discuss how the tumor microenvironment regulates the response and resistance to radiation therapy and what targeted agents have been used to combat stromal-mediated radiation resistance.

Abstract

A tumor is a complex “organ” composed of malignant cancer cells harboring genetic aberrations surrounded by a stroma comprised of non-malignant cells and an extracellular matrix. Considerable evidence has demonstrated that components of the genetically “normal” tumor stroma contribute to tumor progression and resistance to a wide array of treatment modalities, including radiotherapy. Cancer-associated fibroblasts can promote radioresistance through their secreted factors, contact-mediated signaling, downstream pro-survival signaling pathways, immunomodulatory effects, and cancer stem cell-generating role. The extracellular matrix can govern radiation responsiveness by influencing oxygen availability and controlling the stability and bioavailability of growth factors and cytokines. Immune status regarding the presence of pro- and anti-tumor immune cells can regulate how tumors respond to radiation therapy. Furthermore, stromal cells including endothelial cells and adipocytes can modulate radiosensitivity through their roles in angiogenesis and vasculogenesis, and their secreted adipokines, respectively. Thus, to successfully eradicate cancers, it is important to consider how tumor stroma components interact with and regulate the response to radiation. Detailed knowledge of these interactions will help build a preclinical rationale to support the use of stromal-targeting agents in combination with radiotherapy to increase radiosensitivity.

Copper-64 based radiopharmaceuticals for brain tumors and hypoxia imaging

INTRODUCTION

The most common and aggressive primary malignancy of the central nervous system is Glioblastoma that, as a wide range of malignant solid tumor, is characterized by extensive hypoxic regions. A great number of PET radiopharmaceuticals have been developed for the identification of hypoxia in solid tumors, among these, we find copper-based tracers. The aim of the current review paper was to provide an overview of radiocopper compounds applied for preclinical and clinical research in brain tumors and hypoxia imaging or therapy.

EVIDENCE ACQUISITION

Copper offers a wide variety of isotopes, useful for nuclear medicine applications, but only ⁶⁴Cu and ⁶⁷Cu are under the spotlight of the scientific community since being good candidates for theranostic applications. Between the two, ⁶⁴Cu availability and production cost have attracted more interest of the scientific community.

EVIDENCE SYNTHESIS

In order to better understand the application of copper-bis thiosemicarbazones in hypoxia imaging, an overview of the role of hypoxia in cancer, existing non-imaging and imaging techniques for hypoxia identification and promising future avenues regarding hypoxia is necessary. Different proposed uptake mechanisms of [⁶⁴Cu][Cu(ATSM)] inside the cell will be discussed and other ⁶⁴Cu-based tracers for brain tumors described.

CONCLUSIONS

Among radio copper compounds [⁶⁴Cu][Cu(ATSM)] is the most studied radiopharmaceutical for imaging and treatment of brain tumors. Experimental evidence suggested that [⁶⁴Cu][Cu(ATSM)] could be more appropriately considered as a marker of over-reduced intracellular state rather than a pure hypoxia agent. Moreover, preliminary clinical data suggested that [⁶⁴Cu]CuCl<inf>2</inf> can be a potentially useful diagnostic agent for malignancies of the central nervous system (CNS).

Metabolic Signaling Cascades Prompted by Glutaminolysis in Cancer

Simple Summary

Within the last few years, accumulating evidences suggest the involvement of altered metabolisms in human diseases including cancer. Metabolism is defined as the sum of biochemical processes in living organisms that produce and consume energy. Tumor growth requires restructuring of cellular metabolism to meet the increasing demand for building blocks to support the ever-increasing cancer cell numbers. The principle of perturbed metabolism in tumors is known for 50–60 years, it regains greater appreciation within the last few years with the realization that there is interdependency between metabolism and all aspects of cellular function including regulation and control of cell growth. Tumor cells do not need stimulation signals from the surrounding environment to promote cell proliferation; in some cases, the tumor cells can generate their own growth signals. In order to support the continuous tumor cell growth even under stressful conditions, a change in metabolism is necessary to fulfill the continuous demand for energy and building blocks. A better understanding of the relationship between tumor environment and altered cell metabolisms will provide valuable insights to design innovative approaches to limit the supply of energy and macromolecules for the treatment of cancer including melanoma.

Abstract

Aberrant glutamatergic signaling has been implicated in altered metabolic activity and the demand to synthesize biomass in several types of cancer including melanoma. In the last decade, there has been a significant contribution to our understanding of metabolic pathways. An increasing number of studies are now emphasizing the importance of glutamate functioning as a signaling molecule and a building block for cancer progression. To that end, our group has previously illustrated the role of glutamatergic signaling mediated by metabotropic glutamate receptor 1 (GRM1) in neoplastic transformation of melanocytes in vitro and spontaneous development of metastatic melanoma in vivo. Glutamate, the natural ligand of GRM1, is one of the most abundant amino acids in humans and the predominant excitatory neurotransmitter in the central nervous system. Elevated levels of glutaminolytic mitochondrial tricarboxylic acid (TCA) cycle intermediates, especially glutamate, have been reported in numerous cancer cells. Herein, we highlight and critically review metabolic bottlenecks that are prevalent during tumor evolution along with therapeutic implications of limiting glutamate bioavailability in tumors.

Regulation of CD47 expression in cancer cells

CD47 is overexpressed in various types of cancers and it can directly bind with SIRPα, which is mainly located on macrophages. The binding of CD47-SIRPα transmits a “don't eat me” signal, which can prevent cancer cells from immune clearance. Targeting the phagocytosis checkpoint of CD47-SIRPα axis has shown remarkable anticancer effect in preclinical and clinical research, which indicates the potential application of CD47-SIRPα blockade for cancer treatment. In this case, the comprehensive description of the regulation of CD47 in different types of cancer cells has significant implications for furthering our understanding of the role of CD47 in cancer. Based on the current reports, we summarized the regulatory factors, i.e., cytokines, oncogenes, microRNAs as well as enzymes, of CD47 expression in cancer cells. Accordingly, we also proposed several points needing further research, hoping to provide useful insights for the future investigation on the regulation of CD47 in cancers.

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Cytokines, oncogenes, microRNAs and enzymes regulate CD47 expression in cancer.

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CD47 expression could be regulated at the transcriptional, post-transcriptional and post-translational modification level.

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Further studies are required to determine other factors that regulate CD47 expression.

Metabolic Potential of Cancer Cells in Context of the Metastatic Cascade

The metastatic cascade is a highly plastic and dynamic process dominated by cellular heterogeneity and varying metabolic requirements. During this cascade, the three major metabolic pillars, namely biosynthesis, RedOx balance, and bioenergetics, have variable importance. Biosynthesis has superior significance during the proliferation-dominated steps of primary tumour growth and secondary macrometastasis formation and only minor relevance during the growth-independent processes of invasion and dissemination. Consequently, RedOx homeostasis and bioenergetics emerge as conceivable metabolic key determinants in cancer cells that disseminate from the primary tumour. Within this review, we summarise our current understanding on how cancer cells adjust their metabolism in the context of different microenvironments along the metastatic cascade. With the example of one-carbon metabolism, we establish a conceptual view on how the same metabolic pathway can be exploited in different ways depending on the current cellular needs during metastatic progression.

Caveolin-1-Mediated Tumor Suppression Is Linked to Reduced HIF1α S-Nitrosylation and Transcriptional Activity in Hypoxia

Caveolin-1 (CAV1) is a well-established nitric oxide synthase inhibitor, whose function as a tumor suppressor is favored by, but not entirely dependent on, the presence of E-cadherin. Tumors are frequently hypoxic and the activation of the hypoxia-inducible factor-1α (HIF1α) promotes tumor growth. HIF1α is regulated by several post-translational modifications, including S-nitrosylation. Here, we evaluate the mechanisms underlying tumor suppression by CAV1 in cancer cells lacking E-cadherin in hypoxia. Our main findings are that CAV1 reduced HIF activity and Vascular Endothelial Growth Factor expression in vitro and in vivo. This effect was neither due to reduced HIF1α protein stability or reduced nuclear translocation. Instead, HIF1α S-nitrosylation observed in hypoxia was diminished by the presence of CAV1, and nitric oxide synthase (NOS) inhibition by Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) reduced HIF1α transcriptional activity in cells to the same extent as observed upon CAV1 expression. Additionally, arginase inhibition by (S)-(2-Boronoethyl)-L-cysteine (BEC) partially rescued cells from the CAV1-mediated suppression of HIF1α transcriptional activity. In vivo, CAV1-mediated tumor suppression was dependent on NOS activity. In summary, CAV1-dependent tumor suppression in the absence of E-cadherin is linked to reduced HIF1α transcriptional activity via diminished NOS-mediated HIF1α S-nitrosylation.

Estimation of the oxygen enhancement ratio for charged particle radiation

The transformative effect of oxygen on conventional x-ray radiotherapy has long been known, with the presence of molecular oxygen boosting treatment efficacy multi-fold. This effect is present too in charged particle therapy, but the boosting potential decreases with increasing linear energy transfer of the incident radiation. With particle modalities such as proton therapy becoming common-place and emerging technologies like carbon-ion therapy on the horizon, it is pertinent to address the additive dose boost gained from molecular oxygen with high energy radiation, and the implications of this for dose planning. This work establishes an empirical model for oxygen enhancement across the radiotherapy energy spectrum, and discusses implications of this for therapy.

Neuroprotective Effect of HIF Prolyl Hydroxylase Inhibition in an In Vitro Hypoxia Model

A novel potent analog of the branched tail oxyquinoline group of hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitors, neuradapt, has been studied in two treatment regimes in an in vitro hypoxia model on murine primary hippocampal cultures. Neuradapt activates the expression of HIF1 and HIF2 target genes and shows no toxicity up to 20 μM, which is more than an order of magnitude higher than its biologically active concentration. Cell viability, functional activity, and network connectivity between the elements of neuronal networks have been studied using a pairwise correlation analysis of the intracellular calcium fluctuations in the individual cells. An immediate treatment with 1 μМ and 15 μМ neuradapt right at the onset of hypoxia not only protects from the death, but also maintains the spontaneous calcium activity in nervous cells at the level of the intact cultures. A similar neuroprotective effect in the post-treatment scenario is observed for 15 μМ, but not for 1 μМ neuradapt. Network connectivity is better preserved with immediate treatment using 1 μМ neuradapt than with 15 μМ, which is still beneficial. Post-treatment with neuradapt did not restore the network connectivity despite the observation that neuradapt significantly increased cell viability at 1 μМ and functional activity at 15 μМ. The preservation of cell viability and functional activity makes neuradapt promising for further studies in a post-treatment scenario, since it can be combined with other drugs and treatments restoring the network connectivity of functionally competent cells.

Intricate Regulation of Phosphoenolpyruvate Carboxykinase (PEPCK) Isoforms in Normal Physiology and Disease

BACKGROUND

The phosphoenolpyruvate carboxykinase (PEPCK) isoforms are considered as rate-limiting enzymes for gluconeogenesis and glyceroneogenesis pathways. PEPCK exhibits several interesting features such as a) organelle-specific isoforms (cytosolic and a mitochondrial) in vertebrate clade, b) tissue-specific expression of isoforms and c) organism-specific requirement of ATP or GTP as a cofactor. In higher organisms, PEPCK isoforms are intricately regulated and activated through several physiological and pathological stimuli such as corticoids, hormones, nutrient starvation and hypoxia. Isoform-specific transcriptional/translational regulation and their interplay in maintaining glucose homeostasis remain to be fully understood. Mounting evidence indicates the significant involvement of PEPCK isoforms in physiological processes (development and longevity) and in the progression of a variety of diseases (metabolic disorders, cancer, Smith-Magenis syndrome).

OBJECTIVE

The present systematic review aimed to assimilate existing knowledge of transcriptional and translational regulation of PEPCK isoforms derived from cell, animal and clinical models.

CONCLUSION

Based on current knowledge and extensive bioinformatics analysis, in this review we have provided a comparative (epi)genetic understanding of PCK1 and PCK2 genes encompassing regulatory elements, disease-associated polymorphisms, copy number variations, regulatory miRNAs and CpG densities. We have also discussed various exogenous and endogenous modulators of PEPCK isoforms and their signaling mechanisms. A comprehensive review of existing knowledge of PEPCK regulation and function may enable identification of the underlying gaps to design new pharmacological strategies and interventions for the diseases associated with gluconeogenesis.

The Intersection of DNA Damage Response and Ferroptosis-A Rationale for Combination Therapeutics

Ferroptosis is a novel form of iron-dependent cell death characterized by lipid peroxidation. While the importance and disease relevance of ferroptosis are gaining recognition, much remains unknown about its interaction with other biological processes and pathways. Recently, several studies have identified intricate and complicated interplay between ferroptosis, ionizing radiation (IR), ATM (ataxia-telangiectasia mutated)/ATR (ATM and Rad3-related), and tumor suppressor p53, which signifies the participation of the DNA damage response (DDR) in iron-related cell death. DDR is an evolutionarily conserved response triggered by various DNA insults to attenuate proliferation, enable DNA repairs, and dispose of cells with damaged DNA to maintain genome integrity. Deficiency in proper DDR in many genetic disorders or tumors also highlights the importance of this pathway. In this review, we will focus on the biological crosstalk between DDR and ferroptosis, which is mediated mostly via noncanonical mechanisms. For clinical applications, we also discuss the potential of combining ionizing radiation and ferroptosis-inducers for synergistic effects. At last, various ATM/ATR inhibitors under clinical development may protect ferroptosis and treat many ferroptosis-related diseases to prevent cell death, delay disease progression, and improve clinical outcomes.

Targeting the Tumor Core: Hypoxia-Responsive Nanoparticles for the Delivery of Chemotherapy to Pancreatic Tumors

In pancreatic ductal adenocarcinoma (PDAC), early onset of hypoxia triggers remodeling of the extracellular matrix, epithelial-to-mesenchymal transition, increased cell survival, the formation of cancer stem cells, and drug resistance. Hypoxia in PDAC is also associated with the development of collagen-rich, fibrous extracellular stroma (desmoplasia), resulting in severely impaired drug penetration. To overcome these daunting challenges, we created polymer nanoparticles (polymersomes) that target and penetrate pancreatic tumors, reach the hypoxic niches, undergo rapid structural destabilization, and release the encapsulated drugs. In vitro studies indicated a high cellular uptake of the polymersomes and increased cytotoxicity of the drugs under hypoxia compared to unencapsulated drugs. The polymersomes decreased tumor growth by nearly 250% and significantly increased necrosis within the tumors by 60% in mice compared to untreated controls. We anticipate that these polymer nanoparticles possess a considerable translational potential for delivering drugs to solid hypoxic tumors.

Insights into the New Cancer Therapy through Redox Homeostasis and Metabolic Shifts

Modest levels of reactive oxygen species (ROS) are necessary for intracellular signaling, cell division, and enzyme activation. These ROS are later eliminated by the body’s antioxidant defense system. High amounts of ROS cause carcinogenesis by altering the signaling pathways associated with metabolism, proliferation, metastasis, and cell survival. Cancer cells exhibit enhanced ATP production and high ROS levels, which allow them to maintain elevated proliferation through metabolic reprograming. In order to prevent further ROS generation, cancer cells rely on more glycolysis to produce ATP and on the pentose phosphate pathway to provide NADPH. Pro-oxidant therapy can induce more ROS generation beyond the physiologic thresholds in cancer cells. Alternatively, antioxidant therapy can protect normal cells by activating cell survival signaling cascades, such as the nuclear factor erythroid 2-related factor 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap1) pathway, in response to radio- and chemotherapeutic drugs. Nrf2 is a key regulator that protects cells from oxidative stress. Under normal conditions, Nrf2 is tightly bound to Keap1 and is ubiquitinated and degraded by the proteasome. However, under oxidative stress, or when treated with Nrf2 activators, Nrf2 is liberated from the Nrf2-Keap1 complex, translocated into the nucleus, and bound to the antioxidant response element in association with other factors. This cascade results in the expression of detoxifying enzymes, including NADH-quinone oxidoreductase 1 (NQO1) and heme oxygenase 1. NQO1 and cytochrome b5 reductase can neutralize ROS in the plasma membrane and induce a high NAD⁺/NADH ratio, which then activates SIRT1 and mitochondrial bioenergetics. NQO1 can also stabilize the tumor suppressor p53. Given their roles in cancer pathogenesis, redox homeostasis and the metabolic shift from glycolysis to oxidative phosphorylation (through activation of Nrf2 and NQO1) seem to be good targets for cancer therapy. Therefore, Nrf2 modulation and NQO1 stimulation could be important therapeutic targets for cancer prevention and treatment.

Microenvironmental Activation of Nrf2 Restricts the Progression of Nrf2-Activated Malignant Tumors

The transcription factor Nrf2 activates transcription of cytoprotective genes during oxidative and electrophilic insults. Nrf2 activity is regulated by Keap1 in a stress-dependent manner in normal cells, and somatic loss-of-function mutations of Keap1 are known to induce constitutive Nrf2 activation, especially in lung adenocarcinomas, conferring survival and proliferative benefits to tumors. Therefore, several therapeutic strategies that aim to inhibit Nrf2 in tumors have been developed for the treatment of Nrf2-activated cancers. Here we addressed whether targeting Nrf2 activation in the microenvironment can suppress the progression of Nrf2-activated tumors. We combined two types of Keap1-flox mice expressing variable levels of Keap1 with a Kras-driven adenocarcinoma model to generate Keap1-deficient lung tumors surrounded by normal or Keap1-knockdown host cells. In this model system, activation of Nrf2 in the microenvironment prolonged the survival of Nrf2-activated tumor-bearing mice. The Nrf2-activated microenvironment suppressed tumor burden; in particular, preinvasive lesion formation was significantly suppressed. Notably, loss of Nrf2 in bone marrow-derived cells in Nrf2-activated host cells appeared to counteract the suppression of Nrf2-activated cancer progression. Thus, these results demonstrate that microenvironmental Nrf2 activation suppresses the progression of malignant Nrf2-activated tumors and that Nrf2 activation in immune cells at least partially contributes to these suppressive effects. SIGNIFICANCE: This study clarifies the importance of Nrf2 activation in the tumor microenvironment and in the host for the suppression of malignant Nrf2-activated cancers and proposes new cancer therapies utilizing inducers of Nrf2.

CDC20 Knockdown and Acidic Microenvironment Collaboratively Promote Tumorigenesis through Inhibiting Autophagy and Apoptosis

The reconstitution of the tumorigenesis process would shed light on the tumor development study and further drug selection strategies. To construct a tumorigenesis model and explore potential mechanism is of great importance. In our study, we observed that CDC20-knockdown cells cultured in acidic environment exhibited chromosomal instability and better survival ability. The tumorigenic metabolism transformation was confirmed through the increase of the extracellular acidification rate (ECAR) and decrease of the oxygen consumption rate (OCR) in CDC20-knockdown cells. After a long-term culture for 3–4 months, CDC20-knockdown cells in acidic medium showed a strong tumor formation ability by subcutaneous injection into mice that is similar to that of tumor cells. Meanwhile, transcriptome analysis of cells from different stages showed that stage D cells almost resembled the phenotype of immortal cancer cells. The oncogene accumulation laid a firm foundation in the development of the tumorigenesis process by suppressing autophagy and p53-induced apoptosis. Several autophage- and apoptosis-related genes showed inhibition during this tumorigenesis process. In summary, chromosomal instability induced by CDC20 knockdown and acidic microenvironment could collaboratively promote cell tumorigenesis through the downregulation of autophagy and apoptosis.

The Characteristics of Human iPS Cells and siRNA Transfection Under Hypoxia

The characteristics of pluripotent cells have great potential for basic and clinical research and application. We describe the effect of normoxia or hypoxia regarding the proliferation and pluripotency of human iPS cells using colony number counting and real-time polymerase chain reaction (PCR). In addition, the function of hypoxia-inducible factors (HIFs) in human iPS cells under hypoxic conditions is evaluated in relation to the expression of pluripotency markers by siRNA and real-time PCR. Furthermore, we introduce the change of HIF-2α expression when signal transducer and activator of transcription 3 (STAT3) is suppressed by its inhibitor, Stattic or S31 201, using RT-PCR.

A HMCuS@MnO2 nanocomplex responsive to multiple tumor environmental clues for photoacoustic/fluorescence/magnetic resonance trimodal imaging-guided and enhanced photothermal/photodynamic therapy

Hollow mesoporous copper sulfide nanoparticles (HMCuS NPs) are advantageous for loading small-molecule therapeutic drugs coupled with photothermal ablation for synergistic tumor therapy. However, treatment efficacy mediated by HMCuS NPs is not always satisfactory owing to their insensitivity toward the tumor microenvironment (TME), and unpredictable drug leakage may also result in deleterious systemic toxicity. Here, a novel HMCuS@MnO₂-based core-shell nanoplatform was developed as a highly efficient TME modulator, which could alleviate tumor hypoxia, deplete the level of intracellular glutathione (GSH) and trigger the dissolution of Mn²⁺. Moreover, MnO₂, in situ grown on the surface of HMCuS, may act as a gatekeeper by forming a stimulus-responsive plug within the mesoporous structure, which effectively prevented the premature release of encapsulated photosensitizer chlorin e6 (Ce6) and was responsive to the acidic TME for demand-based drug release. Under the condition of 660/808 nm dual-wavelength laser irradiation, hyperthermia-mediated photothermal therapy (PTT) and reactive oxygen species (ROS)-mediated photodynamic therapy (PDT) can be triggered for tumor eradication, which were further enhanced upon the modification of the TME. In the meantime, splendid photoacoustic (PA)/fluorescence (FL)/magnetic resonance (MR) imaging properties of HMCuS@MnO₂/Ce6 (CMC) NPs could enable the realization of more precise, reliable and on-demand combination therapy. In a word, this study illustrated a promising approach to strengthen the efficacy of HMCuS-based nanotherapeutics, which would definitely promote the further exploitation of smarter nanoplatforms for synergistic disease management.

Withaferin A suppresses breast cancer cell proliferation by inhibition of the two-pore domain potassium (K2P9) channel TASK-3

Withaferin A (WFA), a C₅,C₆-epoxy steroidal lactone isolated from the medicinal plant Withania somnifera (L.) Dunal, inhibits growth of tumor cells in different cancer types. However, the mechanisms underlying the effect of WFA on tumor cells are not fully understood. In the present study, we evaluated the blockade of TASK-3 channels by WFA in TASK-3-expressing HEK-293 cells. Explore if the WFA-mediated TASK-3 blockade can be used as a pharmacological tool to decrease the cell viability in cancer cells. A combination of functional experiments (patch-clamp, gene downregulation, overexpression and pharmacological inhibition) and molecular docking analysis were used to get insights into the mechanism by which the inhibition of TASK-3 by WFA affects the growth and viability of cancer cells. Withaferin A was found to inhibit the activity of TASK-3 channels. The inhibitory effect of Withaferin A on TASK-3 potassium currents was dose-dependent and independent of voltage. Molecular modeling studies identified putative WFA-binding sites in TASK-3 channel involved the channel blockade. In agreements with the molecular modeling predictions, mutation of residues F125 to A (F125A), L197 to V (L197 V) and the double mutant F125A-L197 V markedly decreased the WFA-induced inhibition of TASK-3. Finally, the cytotoxic effect of WFA was tested in MDA-MB-231 human breast cancer cells transfected with TASK-3 or shRNA that decreases TASK-3 expression. Together, our results show that the cytotoxic effect of WFA on fully transformed MDA-MB-231 cells depends on the expression of TASK-3. Herein, we also provide insights into the mechanism of TASK-3 inhibition by WFA.

Quantitative MS-Based Proteomics: Comparing the MCF-7 Cellular Response to Hypoxia and a 2-Oxoglutarate Analogue

The hypoxia-inducible factors (HIFs) are key transcription factors in determining cellular responses involving alterations in protein levels in response to limited oxygen availability in animal cells. 2-Oxoglutarate-dependent oxygenases play key roles in regulating levels of HIF and its transcriptional activity. We describe MS-based proteomics studies in which we compared the results of subjecting human breast cancer MCF-7 cells to hypoxia or treating them with a cell-penetrating derivative (dimethyl N-oxalylglycine; DMOG) of the stable 2OG analogue N-oxalylglycine. The proteomic results are consistent with reported transcriptomic analyses and support the proposed key roles of 2OG-dependent HIF prolyl- and asparaginyl-hydroxylases in the hypoxic response. Differences between the data sets for hypoxia and DMOG might reflect context-dependent effects or HIF-independent effects of DMOG.

Yes-associated protein (YAP) and transcriptional coactivator with a PDZ-binding motif (TAZ): a nexus between hypoxia and cancer

Hypoxia is a common feature of solid tumors. As transcription factors, hypoxia-inducible factors (HIFs) are the master regulators of the hypoxic microenvironment; their target genes function in tumorigenesis and tumor development. Intriguingly, both yes-associated protein (YAP) and its paralog transcriptional coactivator with a PDZ-binding motif (TAZ) play fundamental roles in the malignant progression of hypoxic tumors. As downstream effectors of the mammalian Hippo pathway, YAP and/or TAZ (YAP/TAZ) are phosphorylated and sequestered in the cytoplasm by the large tumor suppressor kinase 1/2 (LATS1/2)-MOB kinase activator 1 (MOB1) complex, which restricts the transcriptional activity of YAP/TAZ. However, dephosphorylated YAP/TAZ have the ability to translocate to the nucleus where they induce transcription of target genes, most of which are closely related to cancer. Herein we review the tumor-related signaling crosstalk between YAP/TAZ and hypoxia, describe current agents and therapeutic strategies targeting the hypoxia–YAP/TAZ axis, and highlight questions that might have a potential impact in the future.

Expression, function and clinical application of stanniocalcin-1 in cancer

The glycoprotein stanniocalcin-1 functions as a regulatory endocrine hormone that maintains the balance of calcium and phosphorus in bony fish and as a paracrine/autocrine factor involved in many physiological/pathological processes in humans, including carcinogenesis. In this review, we provide an overview of (a) the possible mechanisms through which STC1 affects the malignant properties of cancer, (b) transcriptional and post-transcriptional regulation pathways of STC1 and (c) the potential clinical relevance of STC1 as a cancer biomarker and even a therapeutic target in the future. Exploring the role of STC1 in cancer development may provide a better understanding of the tumorigenesis process in humans and may facilitate finding an effective therapeutic method against cancer.

Intelligent Bimetallic Nanoagents as Reactive Oxygen Species Initiator System for Effective Combination Phototherapy

Phototherapy is a promising oncotherapy method. However, there are various factors greatly restricted phototherapy development, including poor tumor-specific accumulation, the hypoxia in solid tumor, and the systemic phototoxicity of photosensitizer. Herein, a tumor microenvironment (TME)-responsive intelligent bimetallic nanoagents (HSA-Pd-Fe-Ce6 NAs) composed of human serum albumin (HSA), palladium-iron (Pd-Fe) bimetallic particles, and chlorin e6 (Ce6) was designed for effective combination phototherapy. The Pd-Fe part in the HSA-Pd-Fe-Ce6 NAs would react with the endogenous hydrogen peroxide (H₂O₂) in an acidic ambiance within tumor to generate cytotoxic superoxide anion free radical through the “Fenton-like reaction.” H₂O₂, coupled with highly toxic singlet oxygen (¹O₂) caused by the Ce6 component under the irradiation of 660 nm laser, resulted in synergistic cancer therapy effects in hypoxia surroundings. Besides, this nanoagents could result in hyperpyrexia-induced cell apoptosis because of superior absorption performance in near-infrared wavelength window bringing about excellent photothermal conversion efficiency. The cell cytotoxicity results showed that the survival rate after treated by 40 μg mL^–1 nanoagents was only 17%, which reveals that the HSA-Pd-Fe-Ce6 NAs had the advantage of efficient and controllable phototherapy. In short, it exhibited excellent hypoxia-resistant combination phototherapy efficacy in vitro. Therefore, the multifunctional nanoagents are powerful and provide a new avenue for effective combination phototherapy.

Response of pH-Sensitive Doxorubicin Nanoparticles on Complex Tumor Microenvironments by Tailoring Multiple Physicochemical Properties

Cellular internalization, delivery efficiency, and therapeutic efficacy of nanoparticles vary according to the microenvironmental complexity for tumor types. Adjusting their physicochemical properties, such as surface properties and size, has significant potential for dealing with such complexities. Herein, we prepare four types of pH-sensitive doxorubicin nanoparticles (DOX-D1, DOX-D2, DOX-W1, and DOX-W2 Nano) using simply changing reaction medium or reactant ratio. DOX-D1 and DOX-D2 Nano exhibit similar surface characteristics (surface coating and targeting ligand content) and different size, while both DOX-W Nano examples present similar surface characteristics and size. And they can re-self-assemble into smaller particles in blood-mimic conditions and the order of size is as follows: DOX-D1> DOX-D2 ≈ DOX-W Nano, and DOX-W Nano has a higher targeting ligand content than DOX-D Nano. Thus, the bioactivities in vitro and tumor microenvironment responses of DOX-D1, DOX-D2, and DOX-W1 are further investigated due to their different physicochemical properties. DOX-W1 Nano exhibits a higher cellular uptake, a stronger antiproliferation than DOX-D1 and DOX-D2 Nano attributed to its smaller size, and a higher targeting moiety content. Despite the similar sizes of DOX-W1 and DOX-D2, DOX-D2 Nano shows a greater in vitro blood-brain barrier (BBB) permeability related to its surface coating. Interestingly, DOX-D1 with suitable size and surface property can efficiently bypass the BBB and deliver to an intracranial glioma; in comparison DOX-W1 Nano has excellent targeting efficiency in subcutaneous tumors (glioma and breast cancer). Accordingly, DOX-D1 Nano is preferential for the treatment of intracranial glioma while DOX-W1 Nano exhibits potent killing ability for subcutaneous tumors. Our work suggests tailoring multiple physicochemical properties of nanoparticles can play a significant role in addressing tumor microenvironment complexity.