Hypoxia-inducible factors and cancer

Xanthatin nanocrystals exert anti-inflammatory properties against TNFα-primed 2D monolayers and in 3D spheroids of human HT29 colorectal cancer cells

Poor water-solubility of emerging new chemotherapeutic drugs lead to low absorption and tissue bioavailability. Improved drug delivery has therefore recently been achieved through the versatile physico-chemical properties of nanocrystals (NCs) in targeted cancer therapies. Here, nanocrystalization was used with xanthatin, a not highly water-soluble natural sesquiterpene lactone compound that possesses anti-tumour properties and which was recently investigated for potential use in the treatment of cancer and autoimmune diseases. Given that tumour-promoting inflammation is a hallmark of colorectal cancer (CRC), and that epidemiological studies associated inflammatory biomarkers to CRC poor prognosis and therapy resistance, the anti-inflammatory properties of xanthatin NCs were assessed in 2D monolayers and in 3D spheroids of a human HT29 CRC cell model. The 3D spheroids being a model recapitulating a cancer stem cells and chemoresistant phenotype. HT29 2D monolayer cell response was first tested against four pro-inflammatory inducers including phorbol-12-myristate-13-acetate, tumour necrosis factor alpha (TNFα), transforming growth factor beta, and Concanavalin A. Of these inducers, HT29 cell response to TNFα resulted in the most elevated expression of cyclooxygenase (COX)-2 which was prevented by commercial xanthatin along with the phosphorylation of the extracellular signal-regulated kinase 1/2 and of IkappaB (IκB). Alteration of 3D spheroids formation and of the inflammatory/immunity transcriptomic signature was also found better altered by xanthatin NCs in comparison to commercial xanthatin and the isolated molecule. Collectively, our data indicate that xanthatin nanocrystallization did not alter the potential in vitro anti-inflammatory and anticancer properties of xanthatin against a 3D CRC chemoresistance cellular model. These properties make NCs a significant advancement in the field of cancer theranostics to improve patient outcomes.

Intracellular Mutual Amplification of Oxidative Stress and Inhibition Multidrug Resistance for Enhanced Sonodynamic/Chemodynamic/Chemo Therapy

Emerging noninvasive treatments, such as sonodynamic therapy (SDT) and chemodynamic therapy (CDT), have developed as promising alternatives or supplements to traditional chemotherapy. However, their therapeutic effects are limited by the hypoxic environment of tumors. Here, a biodegradable nanocomposite-mesoporous zeolitic-imidazolate-framework@MnO₂ /doxorubicin hydrochloride (mZMD) is developed, which achieves enhanced SDT/CDT/chemotherapy through promoting oxidative stress and overcoming the multidrug resistance. The mZMD decomposes under both ultrasound (US) irradiation and specific reactions in the tumor microenvironment (TME). The mZM composite structure reduces the recombination rate of e^- and h⁺ to improve SDT. MnO₂ not only oxidizes glutathione in tumor cells to enhance oxidative stress, but also converts the endogenic H₂ O₂ into O₂ to improve the hypoxic TME, which enhances the effects of chemotherapy/SDT. Meanwhile, the generated Mn²⁺ catalyzes the endogenic H₂ O₂ into ·OH for CDT, and acts as magnetic resonance imaging agent to guide therapy. In addition, dissociated Zn²⁺ further breaks the redox balance of TME, and co-inhibits the expression of P-glycoprotein (P-gp) with generated ROS to overcome drug resistance. Thus, the as-prepared intelligent biodegradable mZMD provides an innovative strategy to enhance SDT/CDT/chemotherapy.

Correlation between imaging and tissue biomarkers of hypoxia in squamous cell cancer of the head and neck

The aim of this study was to correlate endogenous tissue biomarkers of hypoxia with quantitative imaging parameters derived from ¹⁸F-fluoro-misonidazole (F-MISO) and ¹⁸F-fluoro-deoxy-glucose (FDG) positron emission tomography/computed tomography (PET/CT) and clinical outcomes in locoregionally advanced head and neck squamous cell carcinoma (HNSCC). Tumor-tissue blocks of HNSCC patients with pretreatment F-MISO-PET/CT and FDG-PET/CT were de-archived for expression of hypoxia-inducible factor-1 alpha (HIF-1α) subunit, carbonic anhydrase-IX (CA-IX), and glucose transporter subunit-1 (GLUT-1) using immunohistochemistry (IHC). The intensity of staining was graded and correlated with quantitative imaging parameters and with disease-related outcomes. Tissue blocks were analyzed for 14 of 20 patients. On IHC, median H-scores for HIF-1α, CA-IX, and GLUT-1 were 130, 0, and 95, respectively. No significant correlation of tissue biomarkers of hypoxia with quantitative imaging parameters was found. However, borderline significant correlation was seen for H-scores of CA-IX with hypoxic tumor volume (HTV) (r = 0.873, P = 0.054) and fractional hypoxic volume (r = 0.824, P = 0.086) derived from F-MISO-PET/CT. At a median follow-up of 43 months, 5-year Kaplan-Meier estimates of locoregional control, disease-free survival, and overall survival were 53%, 43%, and 40%, respectively. Increased expression of HIF-1α or GLUT-1 (dichotomized by median H-scores) was not individually associated with disease-related outcomes. However, a combination of high HTV (>4.89cc) with above median H-scores of either HIF-1α (>130) and/or GLUT-1 (>95) was associated with worse clinical outcomes. None of the three patients with such "adverse hypoxic profile" were long-term survivors. There is no significant correlation of endogenous tissue biomarkers of hypoxia (HIF-1α, CA-IX, and GLUT-1) with quantitative imaging parameters (on F-MISO-PET/CT and FDG-PET/CT) or long-term outcomes in HNSCC. However, a combination of both can identify a subgroup of patients with adverse outcomes.

Effect of an ionic antineoplastic agent Cytoreg on blood chemistry in a Wistar rat model

Cytoreg is an ionic therapeutic agent comprising a mixture of hydrochloric, sulfuric, phosphoric, hydrofluoric, oxalic, and citric acids. In diluted form, it has demonstrated efficacy against human cancers in vitro and in vivo. Although Cytoreg is well tolerated in mice, rats, rabbits, and dogs by oral and intravenous administration, its mechanism of action is not documented. The acidic nature of Cytoreg could potentially disrupt the pH and levels of ions and dissolved gases in the blood. Here, we report the effects of the intravenous administration of Cytoreg on the arterial pH, oxygen and carbon dioxide pressures, and bicarbonate, sodium, potassium, and chloride concentrations. Our results demonstrate that Cytoreg does not disturb the normal blood pH, ion levels, or carbon dioxide content, but increases oxygen levels in rats. These data are consistent with the excellent tolerability of intravenous Cytoreg observed in rabbits, and dogs. The study was approved by the Bioethics Committee of the University of the Andes, Venezuela (CEBIOULA) (approval No. 125) on November 3, 2019.

Berberine-A potent chemosensitizer and chemoprotector to conventional cancer therapies

Chemotherapy and radiotherapy are mainstay treatments for cancer patients. However, their clinical outcomes are highly limited by the resistance of malignant tumors to these therapies and the incurrence of serious damages in vital organs. This in turn necessitates the development of adjunct drugs that overcomes chemo/radioresistance in refractory cancers and protects vital organs from the cytotoxic effects of cancer therapies. In recent years, Berberine (BBR), a natural isoquinoline alkaloid has garnered more attention due to its potent chemosensitizing and chemoprotective properties. BBR effectively sensitizes refractory cancers to chemotherapy and radiotherapy by ameliorating the diverse events underlying therapy resistance. Furthermore, it protects the heart, liver, lungs, and kidneys from severe damages caused by these therapies. In this review, we discuss the molecular mechanisms underlying the chemo/radiosensitizing and chemo/radioprotective potential of BBR during cancer treatment. Also, we highlight the limitations that hamper the clinical application of BBR as an adjunct drug and how novel innovations have been made in recent years to circumvent these challenges.

Unlocking mammalian regeneration through hypoxia inducible factor one alpha signaling

Historically, the field of regenerative medicine has aimed to heal damaged tissue through the use of biomaterials scaffolds or delivery of foreign progenitor cells. Despite 30 years of research, however, translation and commercialization of these techniques has been limited. To enable mammalian regeneration, a more practical approach may instead be to develop therapies that evoke endogenous processes reminiscent of those seen in innate regenerators. Recently, investigations into tadpole tail regrowth, zebrafish limb restoration, and the super-healing Murphy Roths Large (MRL) mouse strain, have identified ancient oxygen-sensing pathways as a possible target to achieve this goal. Specifically, upregulation of the transcription factor, hypoxia-inducible factor one alpha (HIF-1α) has been shown to modulate cell metabolism and plasticity, as well as inflammation and tissue remodeling, possibly priming injuries for regeneration. Since HIF-1α signaling is conserved across species, environmental or pharmacological manipulation of oxygen-dependent pathways may elicit a regenerative response in non-healing mammals. In this review, we will explore the emerging role of HIF-1α in mammalian healing and regeneration, as well as attempts to modulate protein stability through hyperbaric oxygen treatment, intermittent hypoxia therapy, and pharmacological targeting. We believe that these therapies could breathe new life into the field of regenerative medicine.

Correlative analyses between tissue-based hypoxia biomarkers and hypoxia PET imaging in head and neck cancer patients during radiochemotherapy-results from a prospective trial

PURPOSE

Tumor hypoxia impairs the response of head-and-neck cancer (HNSCC) patients to radiotherapy and can be detected both by tissue biomarkers and PET imaging. However, the value of hypoxia biomarkers and imaging for predicting HNSCC patient outcomes are incompletely understood, and potential correlations between tissue and PET data remain to be elucidated. Here, we performed exploratory analyses of potential correlations between tissue-based hypoxia biomarkers and longitudinal hypoxia imaging in a prospective trial of HNSCC patients.

METHODS

Forty-nine patients undergoing chemoradiation for locally advanced HNSCCs were enrolled in this prospective trial. They underwent baseline biopsies and [¹⁸F]FDG PET imaging and [¹⁸F]FMISO PET at weeks 0, 2, and 5 during treatment. Immunohistochemical analyses for p16, Ki67, CD34, HIF1α, CAIX, Ku80, and CD44 were performed, and HPV status was assessed. Biomarker expression was correlated with biological imaging information and patient outcome data.

RESULTS

High HIF1α tumor levels significantly correlated with increased tumor hypoxia at week 2 as assessed by the difference in the [¹⁸F]FMISO tumor-to-background ratios, and high HIF1α and CAIX expressions were both associated with a deferred decrease in hypoxia between weeks 2 and 5. Loco-regional recurrence rates after radiotherapy were significantly higher in patients with high CAIX expression and also increased for high levels of the DNA repair factor Ku80. HPV status did not correlate with any of the tested hypoxia biomarkers, and HPV-positive patients showed higher loco-regional control rates and progression-free survival independent of their hypoxia dynamics.

CONCLUSION

In this exploratory trial, high expression of the tissue-based hypoxia biomarkers HIF1α and CAIX correlated with adverse hypoxia dynamics in HNSCCs during chemoradiation as assessed by PET imaging, and high CAIX levels were associated with increased loco-regional recurrence rates. Hence, hypoxia biomarkers warrant further investigations as potential predictors of hypoxia dynamics and hypoxia-associated radiation resistance.

Caffeic acid phenethyl ester (CAPE) possesses pro-hypoxia and anti-stress activities: bioinformatics and experimental evidences

Honeybee propolis and its bioactive component, caffeic acid phenethyl ester (CAPE), are known for a variety of therapeutic potentials. By recruiting a cell-based reporter assay for screening of hypoxia-modulating natural drugs, we identified CAPE as a pro-hypoxia factor. In silico studies were used to probe the capacity of CAPE to interact with potential hypoxia-responsive proteins. CAPE could not dock into hypoxia inducing factor (HIF-1), the master regulator of hypoxia response pathway. On the other hand, it was predicted to bind to factor inhibiting HIF (FIH-1). The active site residue (Asp201) of FIH-1α was involved in hydrogen bond formation with CAPE and its analogue, caffeic acid methyl ester (CAME), especially in the presence of Fe and 2-oxoglutaric acid (OGA). We provide experimental evidence that the low doses of CAPE, that did not cause cytotoxicity or anti-migratory effect, activated HIF-1α and inhibited stress-induced protein aggregation, a common cause of age-related pathologies. Furthermore, by structural homology search, we explored and found candidate compounds that possess stronger FIH-1 binding capacity. These compounds could be promising candidates for modulating therapeutic potential of CAPE, and its recruitment in treatment of protein aggregation-based disorders.

Cancer risk associated with living at high altitude in Ecuadorian population from 2005 to 2014

Background and aims

Cancer is a leading cause of death in Ecuador with high social and economic impact. This study aims to determinate the influence of living at a high altitude on the risk of developing or dying from cancer among the Ecuadorian population.

Methods

This is an ecological and epidemiological analysis of cancer mortality and prevalence rates, based on national data from the Ecuadorian National Statistics and Census Institute, corresponding to the period between 2005 and 2014. This study includes the analysis of various types of cancer: gastric, colorectal, hepatic/bile duct, breast, uterine/cervix, and lymphatic/hematopoietic, using rates of mortality and prevalence. Additionally, the association between the risk of getting or dying from cancer and living at high altitude was investigated. This comparison was made between the population living in Highlands, over 2000 meters above sea level, and low-lying regions.

Results

Living at high altitude was associated with a higher prevalence of cancer and also with a high mortality rate due to cancer. Risk of getting cancer was related to living at a higher altitude, as well as an increased risk of death by cancer: gastric (OR:1.204; p<0.001), colorectal (OR:1.421; p<0.001), hepatic/bile duct (OR:1.184; p<0.001), breast (OR:1.067; p=0.030), or lymphatic/hematopoietic neoplasms (OR:1.135; p<0.001).

Conclusions

Through an epidemiologic analysis, the association between developing or dying from cancer and living at high altitude was obtained. However, further researche is needed to clarify these findings, something that could have a substantial impact on cancer prevention.

HIF-1α is a Prognostic Marker in Oral Squamous Cell Carcinomas

The critical molecular regulator of hypoxia is the hypoxia-inducible factor 1 alpha (HIF-1α). The prognostic impact of this regulator protein in oral squamous cell carcinomas (OSCC) has not been comprehensively investigated. The aim of this study was to analyze the expression of HIF-1α in 82 patients with OSCC and to correlate it with their disease-specific survival. Immunohistochemical staining for HIF-1α was performed on 82 OSCC specimens using a standard immunoperoxidase technique. The expression of HIF-1α was correlated with poor disease-specific survival for OSCC patients. Patients with negatively or weakly HIF-1α–expressing tumors had a survival rate of 80%, whereas the survival decreased to only 33.6% in case of moderate or strong expression. In multivariate Cox regression analysis, we found a 3.5-fold increased risk of tumor-related death when HIF-1α was strongly expressed (p=0.016) compared to negative or weak expression of HIF-1α. We suggest HIF-1α is an independent prognostic marker in OSCC. Immunohistochemical detection of HIF-1α appears to be useful in the diagnosis of OSCC and to provide prognostic information in addition to TNM stage and histological grade.

Prognostic value of plasma levels of HIF-1a and PGC-1a in breast cancer

Cellular adaptive mechanisms are crucial for tumorigenesis and a common feature in solid tumor progression. Hypoxia-inducible factor-1α (HIF-1α) facilitates the biological response to hypoxia, advancing angiogenesis and metastatic potential of the tumor. The peroxisome proliferator–activated receptor γ coactivators 1α (PGC-1α) enhances mitochondrial biogenesis, favored by migratory/invasive cancer cells. We conducted a prospective, long-term follow up study to determine whether HIF-1α and PGC-1α can be implemented as predictive biomarker in breast cancer. HIF-1α and PGC-1α plasma concentrations were measured in patients and in healthy controls by enzyme linked immune sorbent assay. Breast cancer patients had significantly higher HIF-1α and PGC-1α levels, which correlated with clinicopathological features, overall with more aggressive cancer characteristics. Disease free and overall survival of breast cancer patients with high HIF-1α and PGC-1α were significantly poorer than in patients with low plasma levels. In multivariate analysis, high amount of PGC-1α showed independent prognostic value. Our data suggests that HIF-1α and PGC-1α may be promising, noninvasive, biomarkers with a high potential for future clinical implication to identify subgroups of patients with poorer prognosis and to indicate early, subclinical metastasis.

Iron regulatory protein 2 in ovarian endometrial cysts

Ovarian endometrial cysts cause some kinds of ovarian cancer, and iron is considered as one factor of carcinogenesis. In contrast, hypoxia is associated with progression, angiogenesis, metastasis, and resistance to therapy in cancer. We investigated hypoxia-induced perturbation of iron homeostasis in terms of labile iron, iron deposition, and iron regulatory protein (IRP) in ovarian endometrial cysts. Iron deposition, expression of IRPs, and a protein marker of hypoxia in human ovarian endometrial cysts were analyzed histologically. The concentration of free iron and the pO₂ level of the cyst fluid of human ovarian cysts (n = 9) were measured. The expression of IRP2 under hypoxia was investigated in vitro by using Ishikawa cells as a model of endometrial cells. Iron deposition and the expression of IRP2 and Carbonic anhydrase 9 (CA9) were strong in endometrial stromal cells in the human ovarian endometrial cysts. The average concentration of free iron in the cyst fluid was 8.1 ± 2.9 mg/L, and the pO₂ was 22.4 ± 5.2 mmHg. A cell-based study using Ishikawa cells revealed that IRP2 expression was decreased by an overload of Fe(II) under normoxia but remained unchanged under hypoxia even in the presence of excess Fe(II). An increase in the expression of IRP2 caused upregulation of intracellular iron as a result of the response to iron deficiency, whereas the protein was degraded under iron-rich conditions. We found that iron-rich regions existed in ovarian endometrial cysts concomitantly with the high level of IRP2 expression, which should generally be decomposed upon an overload of iron. We revealed that an insufficient level of oxygen in the cysts is the main factor for the unusual stabilization of IRP2 against iron-mediated degradation, which provides aberrant uptake of iron in ovarian endometrial stromal cells and can potentially lead to carcinogenesis.

Emerging clinical applications of PET based molecular imaging in oncology: the promising future potential for evolving personalized cancer care

This review focuses on the potential of advanced applications of functional molecular imaging in assessing tumor biology and cellular characteristics with emphasis on positron emission tomography (PET) applications with both 18-fluorodeoxyglucose (FDG) and non-FDG tracers. The inherent heterogeneity of cancer cells with their varied cellular biology and metabolic and receptor phenotypic expression in each individual patient and also intra-and inter-lesionally in the same individual mandates for transitioning from a generalized "same-size-fits-all" approach to personalized medicine in oncology. The past two decades have witnessed improvement of oncological imaging through CT, MR imaging, PET, subsequent movement through hybrid or fusion imaging with PET/CT and single-photon emission computerized tomography (SPECT-CT), and now toward the evolving PET/MR imaging. These recent developments have proven invaluable in enhancing oncology care and have the potential to help image the tumor biology at the cellular level, followed by providing a tailored treatment. Molecular imaging, integrated diagnostics or Radiomics, biology-driven interventional radiology and theranostics, all hold immense potential to serve as a guide to give "start and stop" treatment for a patient on an individual basis. This will likely have substantial impact on both treatment costs and outcomes. In this review, we bring forth the current trends in molecular imaging with established techniques (PET/CT), with particular emphasis on newer molecules (such as amino acid metabolism and hypoxia imaging, somatostatin receptor based imaging, and hormone receptor imaging) and further potential for FDG. An introductory discussion on the novel hybrid imaging techniques such as PET/MR is also made to understand the futuristic trends.

Antioxidant Peptide Derived fromSpirulina maximaSuppresses HIF1-Induced Invasive Migration of HT1080 Fibrosarcoma Cells

Hypoxia causes the malignant progression of tumor cells; hence, it has been considered a central issue that must be addressed for effective cancer therapy. The initiation of tumor metastasis requires invasive cell migration. Here, we show that an antioxidant peptide derived fromSpirulina maximasuppresses hypoxia-induced invasive migration of HT1080 human fibrosarcoma cells. HT1080 cells treated with a hypoxia-inducing agent, CoCl2, exhibited an increase in invasive migration and intracellular reactive oxygen species (ROS), which is associated with an increase in the expression of hypoxia-induced factor 1α(HIF1α) accompanied by the activation of PI3K/Akt and ERK1/2. The inhibition of PI3K/Akt and ERK1/2 with specific inhibitors diminished the CoCl2-induced increase in HIF1αexpression and invasive cell migration. Moreover, CoCl2-induced HIF1αexpression was associated with an increase in the expression of molecules downstream ofβ-integrin, such as N-cadherin, vimentin, andβ-catenin. Therefore, theS. maximapeptide effectively attenuated the CoCl2-induced ROS generation and downregulated the HIF1αsignaling pathway involving PI3K/Akt, ERK1/2, andβ-integrin in cells. These results suggest that theS. maximaantioxidant peptide downregulates the HIF1αsignaling pathway necessary for hypoxia-induced invasive migration of HT1080 cells by attenuating intracellular ROS.S. maximapeptide may be an effective constituent in antitumor progression products.

Hypoxia promotes 786-O cells invasiveness and resistance to sorafenib via HIF-2α/COX-2

Accumulating evidences indicated that hypoxia-induced factors and COX-2 play a important role in tumorigenesis in various human cancer. Yet, the relationship between HIFs and COX-2 in human renal cancer remains unclear. The present study was to examine the role of HIFs and COX-2 in the invasiveness and the resistance to target agent in renal cancer cell line (786-O). In 786-O cells, hypoxia induced the increase in the protein expression of HIF1 and HIF2. We also demonstrate that hypoxia up-regulated the protein expression of COX-2 and Snail, but down-regulation of E-cadherin expression in 786-O cells promoted the invasiveness of 786-O cells and enhanced the resistance of 786-O cells to sorafenib. siRNA target to HIF1α, HIF2α and NS398, a selective inhibitor of COX-2, were used in this study. Only siRNA-HIF2α significantly suppressed the protein expression of HIF2 and COX-2, then decreased the invasive ability and resistance of 786-O cells to sorafenib under hypoxia. NS398 attenuated the increase in invasive cells number and the IC50 value of sorafenib induced by hypoxia. In conclusion, our results demonstrated that hypoxia promoted the invasiveness and resistance of 786-O cells to sorafenib via HIF2 and COX-2 and induced the activation of Snail/E-cadherin, suggesting that a signalling mechanism involving HIF2/COX2 modulates invasiveness and resistance to sorafenib in 786-O cells under hypoxia.

Overexpression of hypoxia-inducible factor 1 alpha impacts FoxP3 levels in mycosis fungoides--cutaneous T-cell lymphoma: clinical implications

Mycosis fungoides (MF) is the most common variant of primary cutaneous T-cell lymphoma, and decreased forkhead box P3 (FoxP3) expression has been reported in MF late stages. Hypoxia-inducible factor 1 alpha (HIF-1α) may regulate FoxP3 expression; however, it is unknown whether HIF-1α is expressed in the CD4(+) T cells of MF patients and how it could affect the expression of FoxP3. Therefore, we evaluated the expression of HIF-1α and FoxP3 in CD4(+) T cells obtained from the skin lesions of MF patients. We found increased cell proliferation and an increase in CD4(+) T cells with an aberrant phenotype among early stage MF patients. HIF-1α was overexpressed in these CD4(+) T cells. In addition, we found a decrease in the percentage of FoxP3(+) cells both in the skin of MF patients, when compared with control skin samples, and with disease progression. In addition, a negative correlation was established between HIF-1α and FoxP3 expression. Skin HIF-1α expression in MF patients correlated with the extent of the affected area and increased with the disease progression. Finally, we showed that ex vivo inhibition of HIF-1α degradation increases the percentage of FoxP3(+) T cells in skin lesions. Our results suggest that overexpression of HIF-1α affects the levels of FoxP3 in MF patients, which could have relevant implications in terms of disease outcome.

Autocrine stimulation of clear-cell renal carcinoma cell migration in hypoxia via HIF-independent suppression of thrombospondin-1

Thrombospondin-1 is a matricellular protein with potent antitumour activities, the levels of which determine the fate of many different tumours, including renal carcinomas. However, the factors that regulate this protein remain unclear. In renal carcinomas, hypoxic conditions enhance the expression of angiogenic factors that help adapt tumour cells to their hostile environment. Therefore, we hypothesized that anti-angiogenic factors should correspondingly be dampened. Indeed, we found that hypoxia decreased the thrombospondin-1 protein in several clear cell renal carcinoma cell lines (ccRCC), although no transcriptional regulation was observed. Furthermore, we proved that hypoxia stimulates multiple signals that independently contribute to diminish thrombospondin-1 in ccRCC, which include a decrease in the activity of oxygen-dependent prolylhydroxylases (PHDs) and activation of the PI3K/Akt signalling pathway. In addition, thrombospondin-1 regulation in hypoxia proved to be important for ccRCC cell migration and invasion.

Effect of homotypic and heterotypic interaction in 3D on the E-selectin mediated adhesive properties of breast cancer cell lines

Hematogenous metastasis involves a glycoprotein mediated adhesion cascade of tumor cells with E-selectin on the endothelial layer of the blood vessels. Cell-cell interactions play a major role in cancer metastasis and invasiveness. Intercellular communication between two cancer cells or between a cancer cell with a stromal cell in the microenvironment such as fibroblasts or inflammatory cells play an important role in metastatic invasion. Culturing tumor cells as 3D spheroids can recapitulate these physiologically relevant cell-cell interactions. The heterogeneity in primary tumors is attributed to cell subpopulations with varying degree of invasiveness. Co-culturing cancer cells with different phenotypes as 3D spheroids can mimic this heterogeneity. Here we report the effect of homotypic and heterotypic interactions in breast cancer cells cultured as 3D spheroids on polydimethylsiloxane (PDMS) on the adhesion phenotype to E-selectin. We show that breast cancer cell lines (BT20 and MCF7) propagating as 3D spheroids on PDMS exhibit a stronger interaction with human recombinant E-selectin when compared to their respective monolayer grown counterparts on tissue culture plate (TCP). Matrigel invasion assay also indicated that BT20 and MCF7 spheroids were more invasive than BT20 and MCF7 cells grown as monolayers. To mimic tumor heterogeneity in vitro, a co-culture model included tumorigenic cell lines BT20, MCF7 and a non-tumorigenic mammary epithelial cell line MCF10A. These cell lines were cultured together in equal seeding ratio on PDMS to generate co-culture spheroids. The heterotypic interactions in the co-culture model resulted in enhancement of the adhesion of the most invasive BT20 cell line to E-selectin. BT20 cells in co-culture bound to the greatest degree to soluble E-selectin compared to MCF7 and MCF10A cells in co-culture. Co-invasion assay with co-culture spheroids indicated that BT20 cells in co-culture were more invasive than MCF7 and MCF10A cells. The results presented here indicate that homotypic and heterotypic interaction of cancer cells favor adhesion to E-selectin thus representing a complexity beyond planar cell culture. Also, when cells of different phenotypes are mixed, the heterogeneity enhances the adhesive phenotype and invasiveness of the most invasive cell population. The results challenge the classic use of planar cell culture for evaluating the adhesion of cancer cells to E-selectin and establish our co-culture technique as a model that can help investigative studies in metastasis and invasiveness of breast and other types of cancers.

Correlation of expression of hypoxia-related proteins with prognosis in oral squamous cell carcinoma patients

INTRODUCTION

Hypoxia plays a major role in tumor progression, therapy resistance and for prognosis of oral squamous cell carcinoma (OSCC). The crucial step as a response to hypoxia is the activation and stabilization of the alpha subunit of hypoxia inducible factor 1 (HIF-1α). HIF-1: HIF-1 regulates the expression of different genes to adapt the tumor cells to reduced oxygenation. The HIF-1 system is intrinsic regulated by von Hippel-Lindau protein (pVHL). Main downstream proteins are the glucose transporter 1 (GLUT-1), carbonic anhydrase IX (CAIX), and vascular endothelial growth factor (VEGF). For therapeutical stratification in OSCC, it is important to understand the mechanism caused by hypoxic stress and to comprehend the resulting adaptive process in cancer cells. Therefore, an overview of HIF-1α-depending protein expression, focussed on the expression of GLUT-1, CAIX, and VEGF and their prognostic significance in OSCC is given.

CONCLUSION

Several unique roles of hypoxic pathway in the context of tumor progression are described in this review. As a consequence, a marker panel is proposed to allow a more individualized prognosis in OSCC patients. This marker panel should include beside HIF-1α, pVHL, and GLUT-1.

The G protein-coupled receptor 30 is up-regulated by hypoxia-inducible factor-1alpha (HIF-1alpha) in breast cancer cells and cardiomyocytes

GPR30, also known as GPER, has been suggested to mediate rapid effects induced by estrogens in diverse normal and cancer tissues. Hypoxia is a common feature of solid tumors involved in apoptosis, cell survival, and proliferation. The response to low oxygen environment is mainly mediated by the hypoxia-inducible factor named HIF-1α, which activates signaling pathways leading to adaptive mechanisms in tumor cells. Here, we demonstrate that the hypoxia induces HIF-1α expression, which in turn mediates the up-regulation of GPER and its downstream target CTGF in estrogen receptor-negative SkBr3 breast cancer cells and in HL-1 cardiomyocytes. Moreover, we show that HIF-1α-responsive elements located within the promoter region of GPER are involved in hypoxia-dependent transcription of GPER, which requires the ROS-induced activation of EGFR/ERK signaling in both SkBr3 and HL-1 and cells. Interestingly, the apoptotic response to hypoxia was prevented by estrogens through GPER in SkBr3 cells. Taken together, our data suggest that the hypoxia-induced expression of GPER may be included among the mechanisms involved in the anti-apoptotic effects elicited by estrogens, particularly in a low oxygen microenvironment.

A novel molecular marker for early detection and evaluating prognosis of gastric cancer: N-myc downstream regulated gene-1 (NDRG1)

OBJECTIVE

N-myc downstream regulated gene-1 (NDRG1) is known as a differentiation-related gene that plays important roles in cell differentiation, organ formation, and embryonic development. NDRG1 was recently found to significantly down regulate in a variety of different neoplasms. Its significance in gastric cancer has not been studied.

MATERIALS AND METHODS

NDRG1 was detected at its protein level by immunohistochemistry in formalin-fixed and paraffin-embedded sections with a total of 110 pair gastric cancer specimens including tumor and corresponding paraneoplastic tissues; NDRG1 mRNA was detected by real time-polymerase chain reaction. Meanwhile, the correlations between NDRG1 and clinicopathological factors were observed. Overexpression of NDRG1 has influence on the biological behavior of gastric cancer cell, which was detected by cell growth assay, apoptosis assay, and in vitro motility and invasion assay.

RESULTS

NDRG1 protein was down regulated in gastric cancer tissues, and the NDRG1 low expression rate was 73.6% (79/110). Moreover, NDRG1 expression has a significant inverse correlation with tumor stromal invasion, lymph node metastasis, pathological stage, but not with distant metastasis. The patients with low NDRG1 expression had a significantly shorter survival opportunity than those with high NDRG1 expression. In addition, overexpression of NDRG1 induced early apoptosis and inhibited SGC7901 cell proliferation and its motility and invasion capability.

CONCLUSIONS

NDRG1 plays a significant role in carcinogenesis and preventing the metastasis and invasion of gastric cancer cells. NDRG1 could be developed as a marker contributing to diagnosis and evaluating prognosis in gastric cancer, as well as a potential therapeutic target of gastric cancer.

Identifying mRNA targets of microRNA dysregulated in cancer: with application to clear cell Renal Cell Carcinoma

BACKGROUND

MicroRNA regulate mRNA levels in a tissue specific way, either by inducing degradation of the transcript or by inhibiting translation or transcription. Putative mRNA targets of microRNA identified from seed sequence matches are available in many databases. However, such matches have a high false positive rate and cannot identify tissue specificity of regulation.

RESULTS

We describe a simple method to identify direct mRNA targets of microRNA dysregulated in cancers from expression level measurements in patient matched tumor/normal samples. The word "direct" is used here in a strict sense to: a) represent mRNA which have an exact seed sequence match to the microRNA in their 3'UTR, b) the seed sequence match is strictly conserved across mouse, human, rat and dog genomes, c) the mRNA and microRNA expression levels can distinguish tumor from normal with high significance and d) the microRNA/mRNA expression levels are strongly and significantly anti-correlated in tumor and/or normal samples. We apply and validate the method using clear cell Renal Cell Carcinoma (ccRCC) and matched normal kidney samples, limiting our analysis to mRNA targets which undergo degradation of the mRNA transcript because of a perfect seed sequence match. Dysregulated microRNA and mRNA are first identified by comparing their expression levels in tumor vs normal samples. Putative dysregulated microRNA/mRNA pairs are identified from these using seed sequence matches, requiring that the seed sequence be conserved in human/dog/rat/mouse genomes. These are further pruned by requiring a strong anti-correlation signature in tumor and/or normal samples. The method revealed many new regulations in ccRCC. For instance, loss of miR-149, miR-200c and mir-141 causes gain of function of oncogenes (KCNMA1, LOX), VEGFA and SEMA6A respectively and increased levels of miR-142-3p, miR-185, mir-34a, miR-224, miR-21 cause loss of function of tumor suppressors LRRC2, PTPN13, SFRP1, ERBB4, and (SLC12A1, TCF21) respectively. We also found strong anti-correlation between VEGFA and the miR-200 family of microRNA: miR-200a*, 200b, 200c and miR-141. Several identified microRNA/mRNA pairs were validated on an independent set of matched ccRCC/normal samples. The regulation of SEMA6A by miR-141 was verified by a transfection assay.

CONCLUSIONS

We describe a simple and reliable method to identify direct gene targets of microRNA in any cancer. The constraints we impose (strong dysregulation signature for microRNA and mRNA levels between tumor/normal samples, evolutionary conservation of seed sequence and strong anti-correlation of expression levels) remove spurious matches and identify a subset of robust, tissue specific, functional mRNA targets of dysregulated microRNA.

Generating inhibitors of P-glycoprotein: where to, now?

The prominent role for the drug efflux pump ABCB1 (P-glycoprotein) in mediating resistance to chemotherapy was first suggested in 1976 and sparked an incredible drive to restore the efficacy of anticancer drugs. Achieving this goal seemed inevitable in 1982 when a series of calcium channel blockers were demonstrated to restore the efficacy of chemotherapy agents. A large number of other compounds have since been demonstrated to restore chemotherapeutic sensitivity in cancer cells or tissues. Where do we stand almost three decades since the first reports of ABCB1 inhibition? Unfortunately, in the aftermath of extensive fundamental and clinical research efforts the situation remains gloomy. Only a small handful of compounds have reached late stage clinical trials and none are in routine clinical usage to circumvent chemoresistance. Why has the translation process been so ineffective? One factor is the multifactorial nature of drug resistance inherent to cancer tissues; ABCB1 is not the sole factor. However, expression of ABCB1 remains a significant negative prognostic indicator and is closely associated with poor response to chemotherapy in many cancer types. The main difficulties with restoration of sensitivity to chemotherapy reside with poor properties of the ABCB1 inhibitors: (1) low selectivity to ABCB1, (2) poor potency to inhibit ABCB1, (3) inherent toxicity and/or (4) adverse pharmacokinetic interactions with anticancer drugs. Despite these difficulties, there is a clear requirement for effective inhibitors and to date the strategies for generating such compounds have involved serendipity or simple chemical syntheses. This chapter outlines more sophisticated approaches making use of bioinformatics, combinatorial chemistry and structure informed drug design. Generating a new arsenal of potent and selective ABCB1 inhibitors offers the promise of restoring the efficacy of a key weapon in cancer treatment--chemotherapy.

Regulatory role of HIF-1alpha in the pathogenesis of age-related macular degeneration (AMD)

Age-related macular degeneration (AMD) is a leading cause of irreversible blindness in the elderly throughout the world. AMD is attributed to a complex interaction of genetic and environmental factors. It is characterized by degeneration involving the retinal photoreceptors, retinal pigment epithelium (RPE), and Bruch's membrane, as well as alterations in choroidal capillaries. Aging and age-associated degenerative diseases, such as AMD, are intimately associated with decreased levels of tissue oxygenation and hypoxia that may induce accumulation of detrimental RPE-associated deposits, inflammation and neovascularization processes in retina. Hypoxia-inducible factor (HIF) is the master regulator for hypoxia-induced cellular adaptation that is involved in NF-kappaB signaling and the autophagic protein clearance system. In this review, we discuss role of HIF in AMD pathology and as a possible therapeutic target.

The breast cancer cells response to chronic hypoxia involves the opposite regulation of NF-kB and estrogen receptor signaling

The progression of cancer is associated with tumor's ability to outgrow the existing vasculature resulting in chronic hypoxic pressure, however the molecular mechanism of cancer cell response to chronic hypoxia is poorly understood. In this study we have analyzed the reorganization of estrogen receptor (ER) signaling in breast cancer cells under chronic hypoxia and examined the role of interrelations between ER and NF-kB signaling in cell adaptation to hypoxia. Using long-term culturing of MCF-7 breast cancer cells in hypoxia-mimetic conditions (cobalt chloride) we have established a hypoxia-tolerant subline characterized by HIF-1 hyperexpression that retained the tolerance to hypoxia even when the cells were returned to normoxic conditions. The hypoxia-tolerant cells were characterized by non-affected ER signaling, irreversible suppression of NF-kB activity, and increased sensitivity to cytokine-induced apoptosis. Estradiol treatment suppressed the NF-kB activity in both parent and hypoxia-tolerant MCF-7 cells. In contrast to MCF-7 cells, the exposure of estrogen-independent MCF-7/T2 subline to chronic hypoxia was not accompanied by noticeable changes in NF-kB activity or cell sensitivity to cytokines. Taken together, the results presented demonstrate the importance of interrelations between ER and NF-kB signaling in the response of estrogen-dependent breast cancer cells to chronic hypoxia.

A yeast three-hybrid system that reconstitutes mammalian hypoxia inducible factor regulatory machinery

Background

Several human pathologies, including neoplasia and ischemic cardiovascular diseases, course with an unbalance between oxygen supply and demand (hypoxia). Cells within hypoxic regions respond with the induction of a specific genetic program, under the control of the Hypoxia Inducible Factor (HIF), that mediates their adaptation to the lack of oxygen. The activity of HIF is mainly regulated by the EGL-nine homolog (EGLN) enzymes that hydroxylate the alpha subunit of this transcription factor in an oxygen-dependent reaction. Hydroxylated HIF is then recognized and ubiquitinilated by the product of the tumor suppressor gene, pVHL, leading to its proteosomal degradation. Under hypoxia, the hydroxylation of HIF by the EGLNs is compromised due to the lack of oxygen, which is a reaction cosubstrate. Thus, HIF escapes degradation and drives the transcription of its target genes. Since the progression of the aforementioned pathologies might be influenced by activation of HIF-target genes, development of small molecules with the ability to interfere with the HIF-regulatory machinery is of great interest.

Results

Herein we describe a yeast three-hybrid system that reconstitutes mammalian HIF regulation by the EGLNs and VHL. In this system, yeast growth, under specific nutrient restrictions, is driven by the interaction between the β domain of VHL and a hydroxyproline-containing HIFα peptide. In turn, this interaction is strictly dependent on EGLN activity that hydroxylates the HIFα peptide. Importantly, this system accurately preserves the specificity of the hydroxylation reaction toward specific substrates. We propose that this system, in combination with a matched control, can be used as a simple and inexpensive assay to identify molecules that specifically modulate EGLN activity. As a proof of principle we show that two known EGLN inhibitors, dimethyloxaloylglycine (DMOG) and 6-chlor-3-hydroxychinolin-2-carbonic acid-N-carboxymethylamide (S956711), have a profound and specific effect on the yeast HIF/EGLN/VHL system.

Conclusion

The system described in this work accurately reconstitutes HIF regulation while preserving EGLN substrate specificity. Thus, it is a valuable tool to study HIF regulation, and particularly EGLN biochemistry, in a cellular context. In addition, we demonstrate that this system can be used to identify specific inhibitors of the EGLN enzymes.

Hypoxia-associated markers in gastric carcinogenesis and HIF-2alpha in gastric and gastro-oesophageal cancer prognosis

The study investigated hypoxia-associated markers (HIF-2α, Epo, Epo-R, Glut-1 and VEGF) along with Ki-67 in a gastric carcinogenesis model, and the prognostic significance of hypoxia-inducible factor (HIF)-2α in surgically treated gastro-oesophageal cancer. Protein expression was examined using immunohistochemistry on formalin-fixed, paraffin-embedded biopsies of normal mucosa (n=20), Helicobacter pylori-associated gastritis (n=24), intestinal metaplasia (n=24), dysplasia (n=12) and intestinal (n=19) and diffuse (n=21) adenocarcinoma. Relationships between HIF-2α expression and prognosis were assessed in resection specimens from 177 patients with gastric and gastro-oesophageal junction adenocarcinoma. Expression of all markers increased with progression along the gastric carcinogenesis sequence (P=0.0001). Hypoxia-inducible factor-2α was expressed in 63% of 177 resection specimens and at a high level in 44%. The median overall survival in patients with HIF-2α-expressing tumours was 22 (95% CI 18−26) months, whereas those with HIF-2α-negative tumours had a median survival of 37 (95% CI 29−44) months (P=0.015). Hypoxia-inducible factor-2α had no independent prognostic significance in multivariate analysis. In view of the lack of independent prognostic significance, HIF-2α has no role as a routine prognostic indicator. However, the high expression of HIF-2α suggests that it may be of value as a potential therapeutic target.

Synthesis and structure-activity relationships of 16-modified analogs of 2-methoxyestradiol

A series of 16-modified 2-methoxyestradiol analogs were synthesized and evaluated for antiproliferative activity toward HUVEC and MDA-MB-231 cells, and for susceptibility to conjugation. In addition, the estrogenicity of these analogs was accessed by measuring cell proliferation of the estrogen-dependent cell line MCF7 in response to compound treatment. It was observed that antiproliferative activity dropped as the size of the 16 substituent increased. Selected analogs tested in glucuronidation assays had similar rates of clearance to 2-methoxyestradiol, but had enhanced clearance in sulfonate conjugation assays.