HIF-1 at the crossroads of hypoxia, inflammation, and cancer

Effect of saxagliptin on the expression of HIF-1α in the liver of diabetic rats with fatty liver

The present study was designed to establish a rat model of type 2 diabetes mellitus (T2DM) complicated with fatty liver and to detect the expression of hypoxia-inducible factor-1α (HIF-1α) in liver tissue during the treatment with saxagliptin. Eighty male Wistar rats were randomly divided into two groups. One group was fed with high fat diet to establish T2DM model (n=40), and the other group was fed normally to serve as the control group (n=40). Successfully established rat T2DM models were randomly divided into two groups: The treatment group that received intraperitoneal injection of saxagliptin solution and the other the model group with normal breeding. Blood glucose, blood lipid, liver function and the expression of HIF-1α in liver tissue were detected. Levels of blood glucose in model treatment group were significantly higher than those in the control group (p<0.05). Levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and γ-glutamyl transferase (GGT) in model and treatment group were significantly higher than those in control group (p<0.05), but were significantly reduced with the prolonged treatment (p<0.05). Levels of TC, TG, LDL-C, HDL-C, AST, ALT and GGT and expression level of HIF-1α were significantly higher in the model group than in control group before 3 weeks of treatment (p<0.05), but no significant differences were found after 3 weeks of treatment (p>0.05). Expression level of HIF-1α was decreased with the prolonged treatment, and no significant difference in expression level of HIF-1α was found 3 weeks after treatment (p>0.05). In conclusion, HIF-1α is highly expressed in rats with T2DM and fatty liver. Saxagliptin can effectively improve blood glucose, blood lipid and liver function and reduce the protein expression of HIF-1α in diabetic rats with fatty liver.

Crosstalk between Notch, HIF-1α and GPER in Breast Cancer EMT

The Notch signaling pathway acts in both physiological and pathological conditions, including embryonic development and tumorigenesis. In cancer progression, diverse mechanisms are involved in Notch-mediated biological responses, including angiogenesis and epithelial-mesenchymal-transition (EMT). During EMT, the activation of cellular programs facilitated by transcriptional repressors results in epithelial cells losing their differentiated features, like cell–cell adhesion and apical–basal polarity, whereas they gain motility. As it concerns cancer epithelial cells, EMT may be consequent to the evolution of genetic/epigenetic instability, or triggered by factors that can act within the tumor microenvironment. Following a description of the Notch signaling pathway and its major regulatory nodes, we focus on studies that have given insights into the functional interaction between Notch signaling and either hypoxia or estrogen in breast cancer cells, with a particular focus on EMT. Furthermore, we describe the role of hypoxia signaling in breast cancer cells and discuss recent evidence regarding a functional interaction between HIF-1α and GPER in both breast cancer cells and cancer-associated fibroblasts (CAFs). On the basis of these studies, we propose that a functional network between HIF-1α, GPER and Notch may integrate tumor microenvironmental cues to induce robust EMT in cancer cells. Further investigations are required in order to better understand how hypoxia and estrogen signaling may converge on Notch-mediated EMT within the context of the stroma and tumor cells interaction. However, the data discussed here may anticipate the potential benefits of further pharmacological strategies targeting breast cancer progression.

HIF-1α induces immune escape of prostate cancer by regulating NCR1/NKp46 signaling through miR-224

BACKGROUND

Metastasis of prostate cancer (PCa) is largely affected by natural killer (NK) cells. This study aimed to clarify the mechanisms underlying tumor cells escaping from NK cells mediated by HIF-1α.

METHODS

MiR-224 expression in lymphocytes and HIF-1α protein level in NK cells were determined by qRT-PCR and western blot, respectively. The amount of NKp46⁺ NK cells was detected with flow cytometry. The IFN-γ level was examined by enzyme linked immunosorbent assay (ELISA). NK cells were tested for cytolytic activity with a Non-Radioactive Cytotoxicity Assay, and treated with oxygenglucose deprivation (OGD) for hypoxia simulation. Interaction between miR-224 and NCR1 was evaluated with dual luciferase reporter assay.

RESULTS

MiR-224 was down-regulated in lymphocytes isolated from prostate cancer tissues (n = 10). Overexpression of miR-224 protected prostate cancer from NK cells. HIF-1α increased miR-224 to inhibit the killing capability of NK cells on prostate cancer. MiR-224 controlled the expression of NCR1. Overexpression of miR-224 protected prostate cancer from NK cells through NCR1/NKp46 signaling. Suppression of HIF-1α enhanced the cytotoxicity of NK cells on prostate cancer via miR-224/NCR1 pathway.

CONCLUSION

HIF-1α inhibits NCR1/NKp46 pathway through up-regulating miR-224, which affects the killing capability of NK cells on prostate cancer, thus inducing immune escape of tumor cells.

Antibacterial and Antibiofilm Activities of Cinnamomum Sp. Essential Oil and Cinnamaldehyde: Antimicrobial Activities

To assess the activities of essential oils derived from the trunk bark of Cinnamomum zeylanicum (EOCz) and Cinnamomum cassia (EOCc) as well as cinnamaldehyde on bacterial biofilms of clinical interest. Antimicrobial activity was assessed by the broth microdilution method to determine minimum inhibitory concentrations (MICs). Antibiofilm activity was assessed by quantifying the biomass and determining the number of viable cells. The chemical composition of the essential oils was determined. The results showed that the major component of EOCz and EOCc was cinnamaldehyde. For the assayed substances, biofilm biomasses were reduced by up to 99.9%, and Streptococcus pyogenes, Pseudomonas aeruginosa, and Escherichia coli biofilms were sensitive to all of the concentrations and substances analysed. In cell viability tests, 2 mg/ml of cinnamaldehyde reduced the number of viable cells by 5.74 Log CFU/ml. EOCz, EOCc, and cinnamaldehyde exhibited antimicrobial and antibiofilm activities. This work describes substances with potential use against infections caused by bacterial biofilms.

Radioprotective Effects of Dermatan Sulfate in a Preclinical Model of Oral Mucositis-Targeting Inflammation, Hypoxia and Junction Proteins without Stimulating Proliferation

Oral mucositis is the most frequently occurring early side effect of head-and-neck cancer radiotherapy. Systemic dermatan sulfate (DS) treatment revealed a significant radioprotective potential in a preclinical model of oral mucositis. This study was initiated to elucidate the mechanistic effects of DS in the same model. Irradiation comprised daily fractionated irradiation (5 × 3 Gy/week) over two weeks, either alone (IR) or in combination with daily dermatan sulfate treatment of 4 mg/kg (IR + DS). Groups of mice (n = 5) were sacrificed every second day over the course of 14 days in both experimental arms, their tongues excised and evaluated. The response to irradiation with and without DS was analyzed on a morphological (cell numbers, epithelial thickness) as well as on a functional (proliferation and expression of inflammation, hypoxia and epithelial junction markers) level. The mucoprotective activity of DS can be attributed to a combination of various effects, comprising increased expression of epithelial junctions, reduced inflammation and reduced hypoxia. No DS-mediated effect on proliferation was observed. DS demonstrated a significant mucositis-ameliorating activity and could provide a promising strategy for mucositis treatment, based on targeting specific, radiation-induced, mucositis-associated signaling without stimulating proliferation.

How do cancer cells replenish their fuel supply?

BACKGROUND

Multiple genetic changes, availability of cellular nutrients and metabolic alterations play a pivotal role in oncogenesis AIMS: We focus on cancer cell's metabolic properties, and we outline the cross talks between cellular oncogenic growth pathways in cancer metabolism. The review also provides a synopsis of the relevant cancer drugs targeting metabolic activities that are at various stages of clinical development.

METHODS

We review literature published within the last decade to include select articles that have highlighted energy metabolism crucial to the development of cancer phenotypes.

RESULTS

Cancer cells maintain their potent metabolism and keep a balanced redox status by enhancing glycolysis and autophagy and rerouting Krebs cycle intermediates and products of β-oxydation.

CONCLUSIONS

The processes underlying cancer pathogenesis are extremely complex and remain elusive. The new field of systems biology provides a mathematical framework in which these homeostatic dysregulation principles may be examined for better understanding of cancer phenotypes. Knowledge of key players in cancer-related metabolic reprograming may pave the way for new therapeutic metabolism-targeted drugs and ultimately improve patient care.

Need (more than) two to Tango: Multiple tools to adapt to changes in oxygen availability

Oxygen is a fundamental element for the life of a large number of living organisms allowing an efficient energetic utilization of substrates. Organisms relying on oxygen evolved complex structures for oxygen delivery and biochemical machineries dealing with its safe utilization and the ability to overcome the potentially harmful consequences of changes in oxygen availability. On fact, cells composing complex Eukaryotic organisms are set to live within an optimum narrow range of oxygen, quite specific for each cell type. Minute modifications of oxygen availability, either positive or negative, induce the expression of specific genes, the major actors of this responses being the transcription factors HIF and Nrf2 that control the attempt to cope with low oxygen (hypoxia) or to either high oxygen or to an oxygen "overflow," respectively. This review describes the interaction between these two transcription factors and their interaction with the transcription factor NF-κB acting as a pivotal determinant of final cell response. © 2018 BioFactors, 44(3):207-218, 2018.

BRD7 inhibits the Warburg effect and tumor progression through inactivation of HIF1α/LDHA axis in breast cancer

The bromodomain-containing protein 7 (BRD7) was first identified as a tumor suppressor in nasopharyngeal carcinoma and has critical roles in cancer development and progression. However, the regulatory roles and mechanisms of BRD7 in cancer metabolism are still unknown. In this study, we demonstrated that BRD7 was lowly expressed in breast cancer tissues and was identified as a poor prognostic factor in breast cancer. Meanwhile, BRD7 could suppress cell proliferation, initiate cell apoptosis and reduce aerobic glycolysis, suggesting that BRD7 plays a tumor suppressive roles in breast cancer. Mechanistically, BRD7 could negatively regulate a critical glycolytic enzyme LDHA through directly interaction with its upstream transcription factor, HIF1α, facilitating degradation of HIF1α mediated by ubiquitin–proteasome pathway. Moreover, restoring the expression of LDHA in breast cancer cells could reverse the effect of BRD7 on aerobic glycolysis, cell proliferation, and tumor formation, as well as the expression of cell cycle and apopotosis related molecules such as cyclin D1, CDK4, P21, and c-PARP both in vitro and in vivo. Taken together, these results indicate that BRD7 acts as a tumor suppressor in breast cancer and represses the glycolysis and tumor progression through inactivation of HIF1α/LDHA transcription axis.

Novel natural product therapeutics targeting both inflammation and cancer

Inflammation is recently recognized as one of the hallmarks of human cancer. Chronic inflammatory response plays a critical role in cancer development, progression, metastasis, and resistance to chemotherapy. Conversely, the oncogenic aberrations also generate an inflammatory microenvironment, enabling the development and progression of cancer. The molecular mechanisms of action that are responsible for inflammatory cancer and cancer-associated inflammation are not fully understood due to the complex crosstalk between oncogenic and pro-inflammatory genes. However, molecular mediators that regulate both inflammation and cancer, such as NF-κB and STAT have been considered as promising targets for preventing and treating these diseases. Recent works have further demonstrated an important role of oncogenes (e.g., NFAT1, MDM2) and tumor suppressor genes (e.g., p53) in cancer-related inflammation. Natural products that target these molecular mediators have shown anticancer and anti-inflammatory activities in preclinical and clinical studies. Sesquiterpenoids (STs), a class of novel plant-derived secondary metabolites have attracted great interest in recent years because of their diversity in chemical structures and pharmacological activities. At present, we and other investigators have found that dimeric sesquiterpenoids (DSTs) may exert enhanced activity and binding affinity to molecular targets due to the increased number of alkylating centers and improved conformational flexibility and lipophilicity. Here, we focus our discussion on the activities and mechanisms of action of STs and DSTs in treating inflammation and cancer as well as their structure-activity relationships.

Lutein inhibits proliferation, invasion and migration of hypoxic breast cancer cells via downregulation of HES1

An intratumoral hypoxic microenvironment is frequently observed in solid tumors, including breast cancer. Lutein, a plant-derived compound and non-vitamin A carotenoid, has been demonstrated to possess multiple protective properties including anti-inflammation, anti-oxidative stress and antitumor effects. The main objective of the present research was to elucidate the involvement of lutein in the production of reactive oxygen species (ROS) under hypoxia, the activation of hairy and enhancer of split 1 (HES1), and the proliferation, invasion and migration of breast cancer cells. The human breast cancer cell lines MDA‑MB‑157 and MCF‑7 were exposed to hypoxic conditions and various concentrations of lutein. An MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay was performed to examine cell proliferation, and Annexin V-fluorescein isothiocyanate/propidium iodide staining was performed to analyze the apoptosis ratio. The levels of hypoxia inducible factor-1α (HIF‑1α), NOTCH signaling molecules, HES1 and epithelial-mesenchymal transition (EMT)-associated factors were examined by reverse transcription-quantitative polymerase chain reaction and western blot analysis. Wound healing and Transwell invasion assays were used to detect the invasion and migration of breast cancer cells. Intracellular ROS levels were examined using 2,7-dichlorodihydrofluorescein-diacetate and flow cytometry. The results revealed that cell proliferation was inhibited by lutein in a dose-dependent manner, and the apoptosis ratio gradually increased with lutein treatment under hypoxia as evident from flow cytometry-based analysis. Exposure to lutein inhibited hypoxia-mediated activation of HIF‑1α, NOTCH signaling and HES1 expression, and suppressed the hypoxia-induced expression of EMT-associated factors. Lutein markedly inhibited the invasion and migration of breast cancer cells under hypoxia. Hypoxia-induced production of ROS was also decreased by lutein. Furthermore, the ROS scavenger N‑acetylcysteine also suppressed hypoxia inducible factor 1α and HES1 expression in breast cancer cells during hypoxia, but hydrogen peroxide (H2O2) levels were increased. Taken together, the results of the present study suggested that lutein may be a novel candidate for the chemoprevention of breast cancer. Furthermore, HES1 may be crucial in mediating the involvement of lutein in the suppression of hypoxia-driven ROS-induced breast cancer progression.

Risk management of free radicals involved in air travel syndromes by antioxidants

Frequent air travelers and airplane pilots may develop various types of illnesses. The environmental risk factors associated with air travel syndromes (ATS) or air travel-related adverse health outcomes raised concerns and need to be assessed in the context of risk management and public health. Accordingly, the aim of the present review was to determine ATS, risk factors, and mechanisms underlying ATS using scientific data and information obtained from Medline, Toxline, and regulatory agencies. Additional information was also extracted from websites of organizations, such as the International Air Transport Association (IATA), International Association for Medical Assistance to Travelers (IAMAT), and International Civil Aviation Organization (ICAO). Air travelers are known to be exposed to environmental risk factors, including circadian rhythm disruption, poor cabin air quality, mental stress, high altitude conditions, hormonal dysregulation, physical inactivity, fatigue, biological infections, and alcoholic beverage consumption. Consequences of ATS attributed to air travel include sleep disturbances (e.g., insomnia), mental/physical stress, gastrointestinal disorders, respiratory diseases, circulatory-related dysfunction, such as cardiac arrest and thrombosis and, at worst, mechanical and terrorism-related airplane crashes. Thus safety measures in the cabin before or after takeoff are undertaken to prevent illnesses or accidents related to flight. In addition, airport quarantine systems are strongly recommended to prepare for any ultimate adverse circumstances. Routine monitoring of environmental risk factors also needs to be considered. Frequently, the mechanisms underlying these adverse manifestations involve free radical generation. Therefore, antioxidant supplementation may help to reduce or prevent adverse outcomes by mitigating health risk factors associated with free radical generation.

On the relationships in rhesus macaques between chronic ethanol consumption and the brain transcriptome

This is the first description of the relationship between chronic ethanol self-administration and the brain transcriptome in a non-human primate (rhesus macaque). Thirty-one male animals self-administered ethanol on a daily basis for over 12 months. Gene transcription was quantified with RNA-Seq in the central nucleus of the amygdala (CeA) and cortical Area 32. We constructed coexpression and cosplicing networks, and we identified areas of preservation and areas of differentiation between regions and network types. Correlations between intake and transcription included largely distinct gene sets and annotation categories across brain regions and between expression and splicing; positive and negative correlations were also associated with distinct annotation groups. Membrane, synaptic and splicing annotation categories were over-represented in the modules (gene clusters) enriched in positive correlations (CeA); our cosplicing analysis further identified the genes affected only at the exon inclusion level. In the CeA coexpression network, we identified Rab6b, Cdk18 and Igsf21 among the intake-correlated hubs, while in the Area 32, we identified a distinct hub set that included Ppp3r1 and Myeov2. Overall, the data illustrate that excessive ethanol self-administration is associated with broad expression and splicing mechanisms that involve membrane and synapse genes.

MicroRNA 122, Regulated by GRLH2, Protects Livers of Mice and Patients From Ethanol-Induced Liver Disease

BACKGROUND & AIMS

Chronic, excessive alcohol consumption leads to alcoholic liver disease (ALD) characterized by steatosis, inflammation, and eventually cirrhosis. The hepatocyte specific microRNA 122 (MIR122) regulates hepatocyte differentiation and metabolism. We investigated whether an alcohol-induced decrease in level of MIR122 contributes to development of ALD.

METHODS

We obtained liver samples from 12 patients with ALD and cirrhosis and 9 healthy individuals (controls) and analyzed them by histology and immunohistochemistry. C57Bl/6 mice were placed on a Lieber-DeCarli liquid diet, in which they were fed ethanol for 8 weeks, as a model of ALD, or a control diet. These mice were also given injections of CCl4, to increase liver fibrosis, for 8 weeks. On day 28, mice with ethanol-induced liver disease and advanced fibrosis, and controls, were given injections of recombinant adeno-associated virus 8 vector that expressed the primary miR-122 transcript (pri-MIR122, to overexpress MIR122 in hepatocytes) or vector (control). Two weeks before ethanol feeding, some mice were given injections of a vector that expressed an anti-MIR122, to knock down its expression. Serum and liver tissues were collected; hepatocytes and liver mononuclear cells were analyzed by histology, immunoblots, and confocal microscopy. We performed in silico analyses to identify targets of MIR122 and chromatin immunoprecipitation quantitative polymerase chain reaction analyses in Huh-7 cells.

RESULTS

Levels of MIR122 were decreased in liver samples from patients with ALD and mice on the Lieber-DeCarli diet, compared with controls. Transgenic expression of MIR122 in hepatocytes of mice with ethanol-induced liver disease and advanced fibrosis significantly reduced serum levels of alanine aminotransferase (ALT) and liver steatosis and fibrosis, compared with mice given injections of the control vector. Ethanol feeding reduced expression of pri-MIR122 by increasing expression of the spliced form of the transcription factor grainyhead like transcription factor 2 (GRHL2) in liver tissues from mice. Levels of GRHL2 also were increased in liver tissues from patients with ALD, compared with controls; increases correlated with decreases in levels of MIR122 in human liver. Mice given injections of the anti-MIR122 before ethanol feeding had increased steatosis, inflammation, and serum levels of alanine aminotransferase compared with mice given a control vector. Levels of hypoxia-inducible factor 1 alpha (HIF1α) mRNA, a target of MIR122, were increased in liver tissues from patients and mice with ALD, compared with controls. Mice with hepatocyte-specific disruption of Hif1α developed less-severe liver injury following administration of ethanol, injection of anti-MIR122, or both.

CONCLUSIONS

Levels of MIR122 decrease in livers from patients with ALD and mice with ethanol-induced liver disease, compared with controls. Transcription of MIR122 is inhibited by GRHL2, which is increased in livers of mice and patients with ALD. Expression of an anti-MIR122 worsened the severity of liver damage following ethanol feeding in mice. MIR122 appears to protect the liver from ethanol-induced damage by reducing levels of HIF1α. These processes might be manipulated to reduce the severity of ALD in patients.

Hypoxia-inducible factor-1α regulates epithelial-to-mesenchymal transition in paraquat-induced pulmonary fibrosis by activating lysyl oxidase

Pulmonary fibrosis (PF) is one of the most prevalent causes of death following paraquat (PQ) poisoning. As demonstrated in previous studies by the present authors, epithelial-to-mesenchymal transition (EMT) is associated with PQ-induced PF. In addition, hypoxia-inducible factor-1α (HIF-1α) and lysyl oxidase (LOX) promote EMT following PQ poisoning. However, the association between HIF-1α- and LOX-mediated regulation of EMT remains unclear. The present study investigated the association between HIF-1α and LOX with regard to PQ-induced EMT. A549 and RLE-6TN cells were treated with PQ, and HIF-1α and LOX expression was silenced with short interfering RNAs. Changes in the expression of HIF-1α, LOX, β-catenin and EMT-related makers were detected using real-time quantitative polymerase chain reaction, immunofluorescence, and western blotting. HIF-1α and LOX were associated with PQ-induced EMT, and their expression levels were significantly increased (P<0.05). LOX expression was significantly decreased following PQ poisoning when HIF-1α expression was inhibited (P<0.05). However, the level of HIF-1α did not change significantly when LOX was silenced. The expression level of β-catenin and the degree of EMT were significantly decreased following HIF-1α and LOX silencing in both cell lines (P<0.05). The association between HIF-1α and LOX in regulating EMT during PQ-induced PF may be unidirectional. HIF-1α may regulate PQ-induced EMT through the LOX/β-catenin pathway.

Transcription factors: Time to deliver

Transcription factors (TFs) are at the center of the broad regulatory network orchestrating gene expression programs that elicit different biological responses. For a long time, TFs have been considered as potent drug targets due to their implications in the pathogenesis of a variety of diseases. At the same time, TFs, located at convergence points of cellular regulatory pathways, are powerful tools providing opportunities both for cell type change and for managing the state of cells. This task formulation requires the TF modulation problem to come to the fore. We review several ways to manage TF activity (small molecules, transfection, nanocarriers, protein-based approaches), analyzing their limitations and the possibilities to overcome them. Delivery of TFs could revolutionize the biomedical field. Whether this forecast comes true will depend on the ability to develop convenient technologies for targeted delivery of TFs.

Recent Advances in Comprehending the Signaling Pathways Involved in the Progression of Breast Cancer

This review describes recent advances in the comprehension of signaling pathways involved in breast cancer progression. Calcium sensing receptor (CaSR), caveolae signaling, signaling referred to hypoxia-inducing factors and disturbances in the apoptotic machinery are related to more general biological mechanisms and are considered first. The others refer to signaling pathways of more specific biological mechanisms, namely the heparin/heparin-sulfate interactome, over-expression of miRNA-378a-5p, restriction of luminal and basal epithelial cells, fatty-acid synthesis, molecular pathways related to epithelial to mesenchimal transition (EMT), HER-2/neu gene amplification and protein expression, and the expression of other members of the epithelial growth factor receptor family. This progress in basic research is fundamental to foster the ongoing efforts that use the new genotyping technologies, and aim at defining new prognostic and predictive biomarkers for a better personalized management of breast cancer disease.

Hypoxia/IL-1α axis promotes gastric cancer progression and drug resistance

OBJECTIVE

The microenvironment of tumors constitutes a unique niche that promotes cancer metastasis and resistance. Two remarkable characteristics of this microenvironment are hypoxia and inflammation. Interleukin-1α (IL-1α), an important inflammatory factor, is frequently upregulated in a variety of cancers. This study aimed to investigate the expression of IL-1α in gastric cancer (GC) and explore the relationship between IL-1α and hypoxia.

METHODS

Reverse-transcription polymerase chain reaction was performed to characterize IL-1α expression in different GC cell lines under normoxia or hypoxia. IL-1α expression was characterized in relation to tumor stage and lymph node metastasis of GC and the survival of patients. The effect of IL-1α knockdown under normoxia or hypoxia on cell proliferation, migration and sensitivity to cisplatin was also evaluated. Additionally, hypoxia-inducible factor-1α (HIF-1α) expression in KATO-III cells was either upregulated by ectopic HIF-1α expression or downregulated through shHIF-1α transfection, the effects of which on IL-1α expression was subsequently evaluated.

RESULTS

There was a positive correlation between IL-1α, which was upregulated during hypoxia, and tumor stage, lymph node metastasis and resistance to cisplatin in GC. IL-1α was regulated by HIF1α, and a change in HIF1α expression altered the tumor-promoting effect of IL-1α.

CONCLUSION

The IL-1α/hypoxia axis may be a valuable target for diagnosis and treatment of GC.

N6-methyladenosine is required for the hypoxic stabilization of specific mRNAs

Post-transcriptional regulation of mRNA during oxygen deprivation, or hypoxia, can affect the survivability of cells. Hypoxia has been shown to increase stability of a subset of ischemia-related mRNAs, including VEGF. RNA binding proteins and miRNAs have been identified as important for post-transcriptional regulation of individual mRNAs, but corresponding mechanisms that regulate global stability are not well understood. Recently, mRNA modification by N⁶-methyladenosine (m⁶A) has been shown to be involved in post-transcriptional regulation processes including mRNA stability and promotion of translation, but the role of m⁶A in the hypoxia response is unknown. In this study, we investigate the effect of hypoxia on RNA modifications including m⁶A. Our results show hypoxia increases m⁶A content of poly(A)⁺ messenger RNA (mRNA), but not in total or ribosomal RNA in HEK293T cells. Using m⁶A mRNA immunoprecipitation, we identify specific hypoxia-modified mRNAs, including glucose transporter 1 (Glut1) and c-Myc, which show increased m⁶A levels under hypoxic conditions. Many of these mRNAs also exhibit increased stability, which was blocked by knockdown of m⁶A-specific methyltransferases METTL3/14. However, the increase in mRNA stability did not correlate with a change in translational efficiency or the steady-state amount of their proteins. Knockdown of METTL3/14 did reveal that m⁶A is involved in recovery of translational efficiency after hypoxic stress. Therefore, our results suggest that an increase in m⁶A mRNA during hypoxic exposure leads to post-transcriptional stabilization of specific mRNAs and contributes to the recovery of translational efficiency after hypoxic stress.

The Bidirectional Regulation between MYL5 and HIF-1α Promotes Cervical Carcinoma Metastasis

Myosin light chains (MLC) serve important regulatory functions in a wide range of cellular and physiological processes. Recent research found that MLC are also chromatin-associated nuclear proteins which regulate gene transcription. In this study, the MLC member myosin regulatory light chain 5 (MYL5) expression was upregulated in late stage cervical cancer patients, positively correlated with pelvic lymph node metastasis, and identified as a poor survival indicator. MYL5 overexpression promoted metastasis in cervical cancer in vitro and in vivo models, whereas MYL5 silencing had the converse effect. We demonstrated a bidirectional regulation between MYL5 and hypoxia inducible factor-1α (HIF-1α). HIF-1α activates MYL5 via binding to the hypoxia response element (HRE) in the promoter of MYL5, and MYL5 could sustain HIF-1α expression by tethering to recognition sequence AGCTCC in the HIF-1α promoter region. Clinical data confirmed a positive correlation between MYL5 and HIF-1α. In summary, our data show that MYL5 may act as a prognosis predictive factor in cervical carcinoma, and strategies that inhibit the interaction of MYL5 and HIF-1α may benefit the cervical carcinoma patients with metastasis.

Expression of carbonic anhydrase IX is associated with poor prognosis through regulation of the epithelial‑mesenchymal transition in hepatocellular carcinoma

Carbonic anhydrase 9 (CA9) is a plasma membrane-associated isoenzyme that catalyzes pH regulation under hypoxic conditions. CA9 is transcriptionally regulated by hypoxia-inducible factor 1. Recent studies reported that hypoxia also promoted the epithelial-mesenchymal transition (EMT) in various cancers. In the present study, we evaluated the relationship between CA9 expression and EMT in vitro with two hepatoma cell lines. We also examined the clinical significance of CA9 expression in 117 consecutive patients that underwent hepatectomies for hepatocellular carcinoma (HCC). We evaluated CA9 expression and EMT induction under hypoxia with quantitative RT-PCR, western blot analysis and immunofluorescence staining, in HuH7 and HepG2 cells. We knocked down CA9 expression with small interfering RNA to evaluate the relationship between CA9 and EMT. We found that hypoxia induced CA9 expression in HCC cells and promoted EMT, evidenced by a loss of E-cadherin and an increase in N-cadherin. Twist, a transcriptional regulator of EMT, was also upregulated with hypoxia. The CA9 deficiency attenuated hypoxia-induced changes in E-cadherin and N-cadherin. Immunohistochemical evaluations of patient samples showed that CA9 was expressed in 50.4% of patients (59/117). However, patients with and without CA9 expression were not significantly different in clinicopathological factors. Nevertheless, a multivariate analysis showed that CA9 expression was an independent factor for both recurrence and prognosis among patients that underwent curative surgery for HCC. In conclusion, this study revealed that CA9 expression was a pivotal predictive factor for poor prognosis after radical surgery for HCC. Moreover, the CA9 regulation of the expression of EMT-related molecules represented a mechanism that enhanced malignant potential.

Hypoxia-inducible factor 1α participates in hypoxia-induced epithelial-mesenchymal transition via response gene to complement 32

The aim of the present study was to explore the function of response gene to complement 32 (RGC-32) in hypoxia-induced epithelial-mesenchymal transition (EMT) in pancreatic cancer. Three kinds of hypoxia-inducible factor 1α (HIF-1α) small interfering (si)RNA were synthesized and the different effects on the expression of HIF-1α were detected by western blotting. In human pancreatic cancer BxPC-3 cells, HIF-1α levels were diminished using siRNA transfection or HIF-1α inhibitor pretreatment, and the expression levels of RGC-32 and EMT-associated proteins were analyzed using reverse transcription-quantitative polymerase chain reaction and western blotting. Subsequently, the protein levels of epithelial marker, E-cadherin, and mesenchymal marker, vimentin, were determined by western blotting. Results demonstrated that HIF-1α-Homo-488 siRNA and HIF-1α-Homo-1216 siRNA diminished the protein level of HIF-1α. Compared with normoxia, hypoxia induced the levels of HIF-1α, RGC-32, N-cadherin and vimentin, but suppressed the expression of E-cadherin and cytokeratins. The inhibition of HIF-1α by HIF-1α-Homo-1216 siRNA transfection or HIF-1α inhibitor repressed hypoxia-induced HIF-1α, RGC-32, N-cadherin and vimentin, but increased the expression of E-cadherin and cytokeratins. When RGC-32 was knocked down, hypoxia-induced vimentin was suppressed; however, hypoxia-suppressed N-cadherin was released. In conclusion, the present results demonstrated that hypoxia induced the expression of HIF-1α to activate the levels of RGC-32, in turn to regulate the expression EMT-associated proteins for EMT. These findings revealed the function of RGC-32 in hypoxia-induced EMT and may have identified a novel link between HIF-1α and EMT for pancreatic cancer therapy.

Nitric Oxide Synthase-2-Derived Nitric Oxide Drives Multiple Pathways of Breast Cancer Progression

SIGNIFICANCE

Breast cancer is the second leading cause of cancer-related deaths among women in the United States. Development and progression of malignancy are associated with diverse cell signaling pathways that control cell proliferation, survival, motility, invasion, and metastasis. Recent Advances: An increasing number of clinical studies have implicated a strong relationship between elevated tumor nitric oxide synthase-2 (NOS2) expression and poor patient survival.

CRITICAL ISSUES

Herein, we review what we believe to be key mechanisms in the role(s) of NOS2-derived nitric oxide (NO) as a driver of breast cancer disease progression. High NO increases cyclooxygenase-2 activity, hypoxia inducible factor-1 alpha protein stabilization, and activation of important cell signaling pathways, including phosphoinositide 3-kinase/protein kinase B, mitogen-activated protein kinase, epidermal growth factor receptor, and Ras, through post-translational protein modifications. Moreover, dysregulated NO flux within the tumor microenvironment has other important roles, including the promotion of angiogenesis and modulation of matrix metalloproteinase/tissue inhibitor matrix metalloproteinase associated with tumor progression.

FUTURE DIRECTIONS

The elucidation of these and other NO-driven pathways implicates NOS2 as a key driver of breast cancer disease progression and provides a new perspective in the identification of novel targets that may be therapeutically beneficial in the treatment of estrogen receptor-negative disease. Antioxid. Redox Signal. 26, 1044-1058.

The role of metabolic reprogramming in γ-herpesvirus-associated oncogenesis

The γ-herpesviruses, EBV and KSHV, are closely associated with a number of human cancers. While the signal transduction pathways exploited by γ-herpesviruses to promote cell growth, survival and transformation have been reported, recent studies have uncovered the impact of γ-herpesvirus infection on host cell metabolism. Here, we review the mechanisms used by γ-herpesviruses to induce metabolic reprogramming in host cells, focusing on their ability to modulate the activity of metabolic regulators and manipulate metabolic pathways. While γ-herpesviruses alter metabolic phenotypes as a means to support viral infection and long-term persistence, this modulation can inadvertently contribute to cancer development. Strategies that target deregulated metabolic phenotypes induced by γ-herpesviruses provide new opportunities for therapeutic intervention.

Hypoxic pathobiology of breast cancer metastasis

Dissemination of breast cancer cells (BCCs) to distant sites (metastasis) is the ultimate cause of mortality in patients with breast cancer. Hypoxia (low O₂) is a microenvironmental hallmark of most solid cancers arising as a mismatch between cellular O₂ consumption and supply. Hypoxic selection of BCCs triggers molecular and cellular adaptations dependent upon hypoxia-inducible factors (HIFs), a family of evolutionarily conserved transcriptional activators that coordinate the expression of numerous genes controlling each step of the metastatic process. In this review, we summarize current advances in the understanding of HIF-driven molecular mechanisms that promote BCC metastatic dissemination and patient mortality. In addition, we discuss the clinical and therapeutic implications of HIF targeting in breast cancers.

Hypoxia and Inflammation in Cancer, Focus on HIF and NF-κB

Cancer is often characterised by the presence of hypoxia and inflammation. Paramount to the mechanisms controlling cellular responses under such stress stimuli, are the transcription factor families of Hypoxia Inducible Factor (HIF) and Nuclear Factor of κ-light-chain-enhancer of activated B cells (NF-κB). Although, a detailed understating of how these transcription factors respond to their cognate stimulus is well established, it is now appreciated that HIF and NF-κB undergo extensive crosstalk, in particular in pathological situations such as cancer. Here, we focus on the current knowledge on how HIF is activated by inflammation and how NF-κB is modulated by hypoxia. We summarise the evidence for the possible mechanism behind this activation and how HIF and NF-κB function impacts cancer, focusing on colorectal, breast and lung cancer. We discuss possible new points of therapeutic intervention aiming to harness the current understanding of the HIF-NF-κB crosstalk.

Development of Inhibitors Targeting Hypoxia-Inducible Factor 1 and 2 for Cancer Therapy

Hypoxia is frequently observed in solid tumors and also one of the major obstacles for effective cancer therapies. Cancer cells take advantage of their ability to adapt hypoxia to initiate a special transcriptional program that renders them more aggressive biological behaviors. Hypoxia-inducible factors (HIFs) are the key factors that control hypoxia-inducible pathways by regulating the expression of a vast array of genes involved in cancer progression and treatment resistance. HIFs, mainly HIF-1 and -2, have become potential targets for developing novel cancer therapeutics. This article reviews the updated information in tumor HIF pathways, particularly recent advances in the development of HIF inhibitors. These inhibitors interfere with mRNA expression, protein synthesis, protein degradation and dimerization, DNA binding and transcriptional activity of HIF-1 and -2, or both. Despite efforts in the past two decades, no agents directly inhibiting HIFs have been approved for treating cancer patients. By analyzing results of the published reports, we put the perspectives at the end of the article. The therapeutic efficacy of HIF inhibitors may be improved if more efforts are devoted on developing agents that are able to simultaneously target HIF-1 and -2, increasing the penetrating capacity of HIF inhibitors, and selecting suitable patient subpopulations for clinical trials.

HIF-1 in cancer therapy: two decade long story of a transcription factor

BACKGROUND

Oxygen (O₂) homeostasis is an indispensable requirement of eukaryotes. O₂ concentration in cellular milieu is defined as normoxia (∼21% O₂), physoxia (∼1-13% O₂) or hypoxia (∼0.1-1% O₂). Hypoxia, a striking micro-environmental feature in tumorigenesis, is countered by tumor cells via induction of O₂ governed transcription factor, hypoxia inducible factor-1 (HIF-1). Post discovery, HIF-1 has emerged as a promising anticancer therapeutic target during the last two decades. Recent reports have highlighted that enhanced levels of HIF-1 correlate with tumor metastasis leading to poor patient prognosis.

MATERIAL AND METHODS

A systematic search in PubMed and SciFinder for the literature on HIF-1 biology and therapeutic importance in cancer was carried out.

RESULTS

This review highlights the initial description as well as the recent insights into HIF-1 biology and regulation. We have focused on emerging data regarding varied classes of HIF-1 target genes affecting various levels of crosstalk among tumorigenic pathways. We have emphasized on the fact that HIF-1 acts as a networking hub coordinating activities of multiple signaling molecules influencing tumorigenesis. Emerging evidences indicate role of many HIF-induced proteomic and genomic alterations in malignant progression by mediating a myriad of genes stimulating angiogenesis, anaerobic metabolism and survival of cancer cells in O₂-deficient microenvironment.

CONCLUSIONS

Better understanding of the crucial role of HIF-1 in carcinogenesis could offer promising new avenues to researchers and aid in elucidating various open issues regarding the use of HIF-1 as an anticancer therapeutic target. In spite of large efforts in this field, many questions still remain unanswered. Hence, future investigations are necessary to devise, assess and refine methods for translating previous research efforts into novel clinical practices in cancer treatment.

Deregulated expression of VHL mRNA variants in papillary thyroid cancer

Recent findings demonstrated that a subset of papillary thyroid cancers (PTCs) is characterized by reduced expression of the von Hippel-Lindau (VHL) tumor suppressor gene, and that lowest levels associated with more aggressive PTCs. In the present study, the levels of the two VHL mRNA splicing variants, VHL-213 (V1) and VHL-172 (V2), were measured in a series of 96 PTC and corresponding normal matched tissues by means of quantitative RT-PCR. Variations in the mRNA levels were correlated with patients' clinicopathological parameters and disease-free interval (DFI). The analysis of VHL mRNA in tumor tissues, compared to normal matched tissues, revealed that its expression was either up- or down-regulated in the majority of PTC. In particular, V1 and V2 mRNA levels were altered, respectively, in 78 (81.3%) and 65 (67.7%) out of the 96 PTCs analyzed. A significant positive correlation between the two mRNA variants was observed (p < 0.001). Univariate analysis documented the lack of association between each variant and clinicopathological parameters such as age, tumor size, histology, TNM stage, lymph node metastases, and BRAF mutational status. However, a strong correlation was found between altered V1 or V2 mRNA levels and DFI. Multivariate regression analysis indicated higher V1 mRNA values, along with lymph node metastases at diagnosis, as independent prognostic factors predicting DFI. In conclusion, the data reported demonstrate that VHL gene expression is deregulated in the majority of PTC tissues. Of particular interest is the apparent protective role exerted by VHL transcripts against PTC recurrences.

Targeting cancer-related inflammation in the era of immunotherapy

Recent advances in cancer immunotherapy, particularly immune checkpoint blockade therapy have dramatically changed the therapeutic strategy against advanced malignancies. Still, only a subset of patients shows a good response to any single therapy. Moreover, it remains largely unsolved how we can maintain durable clinical responses, or how we can successfully treat a broader range of cancers by immunotherapy. Growing evidence suggests that the major barrier to more successful cancer immunotherapy is the tumour microenvironment (TME), where chronic inflammation has a predominant role in tumour survival and proliferation, angiogenesis and immunosuppression. Over the past decades, our understanding of cancer-related inflammation has significantly evolved, and now we have various therapeutic options tailored to the TME. These therapeutic strategies include inhibiting inflammatory mediators or their downstream signalling molecules, blocking the recruitment of myeloid cells, modulating immunosuppressive functions in myeloid cells and re-educating the TME. In this review, we discuss the role of cancer-related inflammation as a potential target in the era of immunotherapy.

A novel HIF-1α/VMP1-autophagic pathway induces resistance to photodynamic therapy in colon cancer cells

This is the first report showing that PDT-induced autophagy is directly mediated by HIF-1α and linked to VMP1 as a PDT-induced resistance mechanism.

Longer warm ischemia can accelerate tumor growth through the induction of HIF-1α and the IL-6-JAK-STAT3 signaling pathway in a rat hepatocellular carcinoma model

BACKGROUND

The present study aimed to investigate the impact of the duration of hepatic pedicle clamping (HPC) on tumor growth after major hepatectomy in a rat model.

METHODS

Rats were divided into four groups according to the length of HPC during 70% partial hepatectomy followed by N1S1 tumor cell implantation: group 1, without HPC; group 2, with 5-min HPC; group 3, 10-min HPC; and group 4, 15-min HPC. At three weeks after tumor cell implantation, liver tumor growth and its possible mechanisms were investigated.

RESULTS

The number and largest diameter of liver tumor were significantly greater in group 4. At 6 h after reperfusion, serum levels of inflammatory cytokines including interleukin (IL)-6 were significantly higher in group 4 compared with the other groups. In the tumor tissues, the expression of hypoxia inducible factor (HIF)-1α (P < 0.001 versus group 2, P < 0.001 versus group 3) and that of phospho-signal transducer and activator of transcription 3 (STAT3) (P < 0.001 versus group 2, P = 0.026 versus group 3) were significantly upregulated in group 4.

CONCLUSIONS

Longer HPC followed by reperfusion accelerated hepatocellular carcinoma growth through the induction of HIF-1α and the activation of the IL-6-JAK-STAT3 signaling pathway.

Role of cancer-related inflammation in colon cancer

Chronic inflammation is one of the important mechanisms for the development of colon cancer, and the role of cancer-related inflammation (CRI) in tumor development is a hot research topic in recent years. Therefore, it is very important to clarify the effect and regulation of CRI in colon cancer. Accumulating evidence indicates that transcription factors, cytokines, chemokines, cyclooxygenase-2 and microRNAs play key roles in CRI. This review focuses on the research progress about these molecules in colon cancer.

ERβ regulation of NF-kB activation in prostate cancer is mediated by HIF-1

We examined the regulation of NF-κB in prostate cancer by estrogen receptor β (ERβ) based on the inverse correlation between p65 and ERβ expression that exists in prostate carcinomas and reports that ERβ can inhibit NF-κB activation, although the mechanism is not known. We demonstrate that ERβ functions as a gate-keeper for NF-κB p65 signaling by repressing its expression and nuclear translocation. ERβ regulation of NF-κB signaling is mediated by HIF-1. Loss of ERβ or hypoxia stabilizes HIF-1α, which we found to be a direct driver of IKKβ transcription through a hypoxia response element present in the promoter of the IKKβ gene. The increase of IKKβ expression in ERβ-ablated cells correlates with an increase in phospho-IκBα and concomitant p65 nuclear translocation. An inverse correlation between the expression of ERβ and IKKβ/p65 was also observed in the prostates of ERβ knockout (BERKO) mice, Gleason grade 5 prostate tumors and analysis of prostate cancer databases. These findings provide a novel mechanism for how ERβ prevents NF-κB activation and raise the exciting possibility that loss of ERβ expression is linked to chronic inflammation in the prostate, which contributes to the development of high-grade prostate cancer.

Thiol-Activated HNO Release from a Ruthenium Antiangiogenesis Complex and HIF-1α Inhibition for Cancer Therapy

Metallonitrosyl complexes are promising as nitric oxide (NO) donors for the treatment of cardiovascular, endothelial, and pathogenic diseases, as well as cancer. Recently, the reduced form of NO^– (protonated as HNO, nitroxyl, azanone, isoelectronic with O₂) has also emerged as a candidate for therapeutic applications including treatment of acute heart failure and alcoholism. Here, we show that HNO is a product of the reaction of the Ru^II complex [Ru(bpy)₂(SO₃)(NO)]⁺ (1) with glutathione or N-acetyl-L-cysteine, using met-myoglobin and carboxy-PTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) as trapping agents. Characteristic absorption spectroscopic profiles for HNO reactions with met-myoglobin were obtained, as well as EPR evidence from carboxy-PTIO experiments. Importantly, the product HNO counteracted NO-induced as well as hypoxia-induced stabilization of the tumor-suppressor HIF-1α in cancer cells. The functional disruption of neovascularization by HNO produced by this metallonitrosyl complex was demonstrated in an in vitro angiogenesis model. This behavior is consistent with HNO biochemistry and contrasts with NO-mediated stabilization of HIF-1α. Together, these results demonstrate for the first time thiol-dependent production of HNO by a ruthenium complex and subsequent destabilization of HIF-1α. This work suggests that the complex warrants further investigation as a promising antiangiogenesis agent for the treatment of cancer.

Xanthine oxidoreductase in cancer: more than a differentiation marker

Human xanthine oxidoreductase (XOR) catalyzes the last two steps of purine catabolism and is present in two interconvertible forms, which may utilize O2 or NAD(+) as electron acceptors. In addition to uric acid, XOR products may comprise reactive oxygen and nitrogen species that have many biologic effects, including inflammation, endothelial dysfunction, and cytotoxicity, as well as mutagenesis and induction of proliferation. XOR is strictly modulated at the transcriptional and post-translational levels, and its expression and activity are highly variable in cancer. Xanthine oxidoreductase (XOR) expression has been negatively associated with a high malignity grade and a worse prognosis in neoplasms of the breast, liver, gastrointestinal tract, and kidney, which normally express a high level of XOR protein. However, the level of XOR expression may be associated with a worse outcome in cancer of low XOR-expressing cells, in relation to the inflammatory response elicited through the tissue damage induced by tumor growth. Xanthine oxidoreductase (XOR) has been implicated in the process of oncogenesis either directly because it is able to catalyze the metabolic activation of carcinogenic substances or indirectly through the action of XOR-derived reactive oxygen and nitrogen species. The role of uric acid is characterized by both oxidant and antioxidant action; thus, it is still debatable whether control of uricemia may be helpful to improve the outcomes of tumor illness.

Turmeric Sesquiterpenoids: Expeditious Resolution, Comparative Bioactivity, and a New Bicyclic Turmeronoid

An expeditious strategy to resolve turmerone, the lipophilic anti-inflammatory principle of turmeric (Curcuma longa), into its individual bisabolane constituents (ar-, α-, and β-turmerones, 2-4, respectively) was developed. The comparative evaluation of these compounds against a series of anti-inflammatory targets (NF-κB, STAT3, Nrf2, HIF-1α) evidenced surprising differences, providing a possible explanation for the contrasting data on the activity of turmeric oil. Differences were also evidenced in the profile of more polar bisabolanes between the Indian and the Javanese samples used to obtain turmerone, and a novel hydroxylated bicyclobisabolane ketol (bicycloturmeronol, 8) was obtained from a Javanese sample of turmeric. Taken together, these data support the view that bisabolane sesquiterpenes represent an important taxonomic marker for turmeric and an interesting class of anti-inflammatory agents, whose strict structure-activity relationships are worth a systematic evaluation.

Targeting the hypoxic fraction of tumours using hypoxia-activated prodrugs

The presence of a microenvironment within most tumours containing regions of low oxygen tension or hypoxia has profound biological and therapeutic implications. Tumour hypoxia is known to promote the development of an aggressive phenotype, resistance to both chemotherapy and radiotherapy and is strongly associated with poor clinical outcome. Paradoxically, it is recognised as a high-priority target and one of the therapeutic strategies designed to eradicate hypoxic cells in tumours is a group of compounds known collectively as hypoxia-activated prodrugs (HAPs) or bioreductive drugs. These drugs are inactive prodrugs that require enzymatic activation (typically by 1 or 2 electron oxidoreductases) to generate cytotoxic species with selectivity for hypoxic cells being determined by (1) the ability of oxygen to either reverse or inhibit the activation process and (2) the presence of elevated expression of oxidoreductases in tumours. The concepts underpinning HAP development were established over 40 years ago and have been refined over the years to produce a new generation of HAPs that are under preclinical and clinical development. The purpose of this article is to describe current progress in the development of HAPs focusing on the mechanisms of action, preclinical properties and clinical progress of leading examples.

Targeting the hypoxic fraction of tumours using hypoxia-activated prodrugs

The presence of a microenvironment within most tumours containing regions of low oxygen tension or hypoxia has profound biological and therapeutic implications. Tumour hypoxia is known to promote the development of an aggressive phenotype, resistance to both chemotherapy and radiotherapy and is strongly associated with poor clinical outcome. Paradoxically, it is recognised as a high-priority target and one of the therapeutic strategies designed to eradicate hypoxic cells in tumours is a group of compounds known collectively as hypoxia-activated prodrugs (HAPs) or bioreductive drugs. These drugs are inactive prodrugs that require enzymatic activation (typically by 1 or 2 electron oxidoreductases) to generate cytotoxic species with selectivity for hypoxic cells being determined by (1) the ability of oxygen to either reverse or inhibit the activation process and (2) the presence of elevated expression of oxidoreductases in tumours. The concepts underpinning HAP development were established over 40 years ago and have been refined over the years to produce a new generation of HAPs that are under preclinical and clinical development. The purpose of this article is to describe current progress in the development of HAPs focusing on the mechanisms of action, preclinical properties and clinical progress of leading examples.

Xanthine Oxidoreductase-Derived Reactive Species: Physiological and Pathological Effects

Xanthine oxidoreductase (XOR) is the enzyme that catalyzes the oxidation of hypoxanthine to xanthine and xanthine to uric acid and is widely distributed among species. In addition to this housekeeping function, mammalian XOR is a physiological source of superoxide ion, hydrogen peroxide, and nitric oxide, which can function as second messengers in the activation of various pathways. This review intends to address the physiological and pathological roles of XOR-derived oxidant molecules. The cytocidal action of XOR products has been claimed in relation to tissue damage, in particular damage induced by hypoxia and ischemia. Attempts to exploit this activity to eliminate unwanted cells via the construction of conjugates have also been reported. Moreover, different aspects of XOR activity related to phlogosis, endothelial activation, leukocyte activation, and vascular tone regulation, have been taken into consideration. Finally, the positive and negative outcomes concerning cancer pathology have been analyzed because XOR products may induce mutagenesis, cell proliferation, and tumor progression, but they are also associated with apoptosis and cell differentiation. In conclusion, XOR activity generates free radicals and other oxidant reactive species that may result in either harmful or beneficial outcomes.

Serum Metabolomics to Identify the Liver Disease-Specific Biomarkers for the Progression of Hepatitis to Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy that has region specific etiologies. Unfortunately, 85% of cases of HCC are diagnosed at an advanced stage. Reliable biomarkers for the early diagnosis of HCC are urgently required to reduced mortality and therapeutic expenditure. We established a non-targeted gas chromatography–time of flight–mass spectrometry (GC-TOFMS) metabolomics method in conjunction with Random Forests (RF) analysis based on 201 serum samples from healthy controls (NC), hepatitis B virus (HBV), liver cirrhosis (LC) and HCC patients to explore the metabolic characteristics in the progression of hepatocellular carcinogenesis. Ultimately, 15 metabolites were identified intimately associated with the process. Phenylalanine, malic acid and 5-methoxytryptamine for HBV vs. NC, palmitic acid for LC vs. HBV, and asparagine and β-glutamate for HCC vs. LC were screened as the liver disease-specific potential biomarkers with an excellent discriminant performance. All the metabolic perturbations in these liver diseases are associated with pathways for energy metabolism, macromolecular synthesis, and maintaining the redox balance to protect tumor cells from oxidative stress.

NF-κB and HIF crosstalk in immune responses

Hypoxia and inflammation have been associated with a number of pathological conditions, in particular inflammatory diseases. While hypoxia is mainly associated with the activation of hypoxia‐inducible factors (HIFs), inflammation activates the family of transcription factor called nuclear factor‐kappa B (NF‐κB). An extensive crosstalk between these two main molecular players involved in hypoxia and inflammation has been demonstrated. This crosstalk includes common activating stimuli, shared regulators and targets. In this review, we discuss the current understanding of the role of NF‐κB and HIF in the context of the immune response. We review the crosstalk between HIF and NF‐κB in the control of the immune response in different immune cell types including macrophages, neutrophils and B and T cells. Furthermore the importance of the molecular crosstalk between HIFs and NF‐κB for a variety of medical conditions will be discussed.

Overview of Methods for Overcoming Hindrance to Drug Delivery to Tumors, with Special Attention to Tumor Interstitial Fluid

Every drug used to treat cancer (chemotherapeutics, immunological, monoclonal antibodies, nanoparticles, radionuclides) must reach the targeted cells through the tumor environment at adequate concentrations, in order to exert their cell-killing effects. For any of these agents to reach the goal cells, they must overcome a number of impediments created by the tumor microenvironment (TME), beginning with tumor interstitial fluid pressure (TIFP), and a multifactorial increase in composition of the extracellular matrix (ECM). A primary modifier of TME is hypoxia, which increases the production of growth factors, such as vascular endothelial growth factor and platelet-derived growth factor. These growth factors released by both tumor cells and bone marrow recruited myeloid cells form abnormal vasculature characterized by vessels that are tortuous and more permeable. Increased leakiness combined with increased inflammatory byproducts accumulates fluid within the tumor mass (tumor interstitial fluid), ultimately creating an increased pressure (TIFP). Fibroblasts are also up-regulated by the TME, and deposit fibers that further augment the density of the ECM, thus, further worsening the TIFP. Increased TIFP with the ECM are the major obstacles to adequate drug delivery. By decreasing TIFP and ECM density, we can expect an associated rise in drug concentration within the tumor itself. In this overview, we will describe all the methods (drugs, nutraceuticals, and physical methods of treatment) able to lower TIFP and to modify ECM used for increasing drug concentration within the tumor tissue.