Effects of hypoxia on drug resistance phenotype and genotype in human glioma cell lines

Multidrug Resistance in Cancer: Understanding Molecular Mechanisms, Immunoprevention and Therapeutic Approaches

Cancer is one of the leading causes of death worldwide. Several treatments are available for cancer treatment, but many treatment methods are ineffective against multidrug-resistant cancer. Multidrug resistance (MDR) represents a major obstacle to effective therapeutic interventions against cancer. This review describes the known MDR mechanisms in cancer cells and discusses ongoing laboratory approaches and novel therapeutic strategies that aim to inhibit, circumvent, or reverse MDR development in various cancer types. In this review, we discuss both intrinsic and acquired drug resistance, in addition to highlighting hypoxia- and autophagy-mediated drug resistance mechanisms. Several factors, including individual genetic differences, such as mutations, altered epigenetics, enhanced drug efflux, cell death inhibition, and various other molecular and cellular mechanisms, are responsible for the development of resistance against anticancer agents. Drug resistance can also depend on cellular autophagic and hypoxic status. The expression of drug-resistant genes and the regulatory mechanisms that determine drug resistance are also discussed. Methods to circumvent MDR, including immunoprevention, the use of microparticles and nanomedicine might result in better strategies for fighting cancer.

Multimodal Role of PACAP in Glioblastoma

Glioblastoma multiforme (GBM) is the deadliest form of brain tumors. To date, the GBM therapeutical approach consists of surgery, radiation-therapy and chemotherapy combined with molecules improving cancer responsiveness to treatments. In this review, we will present a brief overview of the GBM classification and pathogenesis, as well as the therapeutic approach currently used. Then, we will focus on the modulatory role exerted by pituitary adenylate cyclase-activating peptide, known as PACAP, on GBM malignancy. Specifically, we will describe PACAP ability to interfere with GBM cell proliferation, as well as the tumoral microenvironment. Considering its anti-oncogenic role in GBM, synthesis of PACAP agonist molecules may open new perspectives for combined therapy to existing gold standard treatment.

Advanced nanomaterials for hypoxia tumor therapy: challenges and solutions

In recent years, nanomaterials and nanotechnology have emerged as vital factors in the medical field with a unique contribution to cancer medicine. Given the increasing number of cancer patients, it is necessarily required to develop innovative strategies and therapeutic modalities to tackle hypoxia, which forms a hallmark and great barrier in treating solid tumors. The present review details the challenges in nanotechnology-based hypoxia, targeting the strategies and solutions for better therapeutic performances. The interaction between hypoxia and tumor is firstly introduced. Then, we review the recently developed engineered nanomaterials towards multimodal hypoxia tumor therapies, including chemotherapy, radiotherapy, and sonodynamic treatment. In the next part, we summarize the nanotechnology-based strategies for overcoming hypoxia problems. Finally, current challenges and future directions are proposed for successfully overcoming the hypoxia tumor problems.

Tumor microenvironment and epithelial mesenchymal transition as targets to overcome tumor multidrug resistance

It is well established that multifactorial drug resistance hinders successful cancer treatment. Tumor cell interactions with the tumor microenvironment (TME) are crucial in epithelial-mesenchymal transition (EMT) and multidrug resistance (MDR). TME-induced factors secreted by cancer cells and cancer-associated fibroblasts (CAFs) create an inflammatory microenvironment by recruiting immune cells. CD11b+/Gr-1+ myeloid-derived suppressor cells (MDSCs) and inflammatory tumor associated macrophages (TAMs) are main immune cell types which further enhance chronic inflammation. Chronic inflammation nurtures tumor-initiating/cancer stem-like cells (CSCs), induces both EMT and MDR leading to tumor relapses. Pro-thrombotic microenvironment created by inflammatory cytokines and chemokines from TAMs, MDSCs and CAFs is also involved in EMT and MDR. MDSCs are the most common mediators of immunosuppression and are also involved in resistance to targeted therapies, e.g. BRAF inhibitors and oncolytic viruses-based therapies. Expansion of both cancer and stroma cells causes hypoxia by hypoxia-inducible transcription factors (e.g. HIF-1α) resulting in drug resistance. TME factors induce the expression of transcriptional EMT factors, MDR and metabolic adaptation of cancer cells. Promoters of several ATP-binding cassette (ABC) transporter genes contain binding sites for canonical EMT transcription factors, e.g. ZEB, TWIST and SNAIL. Changes in glycolysis, oxidative phosphorylation and autophagy during EMT also promote MDR. Conclusively, EMT signaling simultaneously increases MDR. Owing to the multifactorial nature of MDR, targeting one mechanism seems to be non-sufficient to overcome resistance. Targeting inflammatory processes by immune modulatory compounds such as mTOR inhibitors, demethylating agents, low-dosed histone deacetylase inhibitors may decrease MDR. Targeting EMT and metabolic adaptation by small molecular inhibitors might also reverse MDR. In this review, we summarize evidence for TME components as causative factors of EMT and anticancer drug resistance.

Evaluation of the Betulinic Acid-Cisplatin conjugate APC and its precursor DE9B for the treatment of human malignant glioma

Despite the existence of multimodal therapy concepts, glioblastoma remains a tumor type with one of the worst prognoses. In particular, the poor prognosis is due to the lack of therapeutic efficacy of chemical agents and irradiation in hypoxic tumor areas. New therapeutic strategies could improve the treatment of glioblastoma. In this study, we investigated the therapeutic efficacy of a conjugate of cisplatin (DDP), a widely used chemotherapeutic agent, and betulinic acid (BA), a natural product from plane tree bark, in glioblastoma cells under different oxygen conditions. We investigated the effects of the BA-DDP conjugate κN',N''-{3-acetyloxy-BA-28-[2-(2-aminoethyl)aminoethyl]amide} dichlorido platinum(II) (APC) and its precursor 3-acetyloxy-BA-28-[2-(2-aminoethyl)aminoethyl]amide (DE9B) on cytotoxicity, cell growth, apoptosis, migration and radiosensitivity compared to BA or DDP alone under different oxygen conditions. Based on the EC₅₀ values, the precursor DE9B exhibited the strongest cytotoxic effects of the analyzed chemotherapeutic agents. The BA-DDP conjugate APC achieved a moderate cytotoxic effect in glioma cells. Both of the newly developed agents induced cell growth delay, apoptosis and inhibition of migration. Furthermore, additive effects could be achieved in combination with irradiation. In contrast to those of BA and DDP, the cell biological effects of APC and DE9B were not influenced by the oxygen concentration. In this study, the linking of BA and DDP did not produce a compound with additive therapeutic effects on glioblastoma cell lines in vitro. Nevertheless, the results of this study suggest that the precursor DE9B is an effective BA derivative for the treatment of glioblastoma in vitro.

Hyperbaric oxygen increases glioma cell sensitivity to antitumor treatment with a novel isothiourea derivative in vitro

Glioblastoma (GBM) is the most common primary brain tumor. Tumor hypoxia is a pivotal factor responsible for the progression of this malignant glioma, and its resistance to radiation and chemotherapy. Thus, improved tumor tissue oxygenation may promote greater sensitivity to anticancer treatment. Protein kinase D1 (PKD1) protects cells from oxidative stress, and its abnormal activity serves an important role in multiple malignancies. The present study examined the effects of various oxygen conditions on the cytotoxic potential of the novel isothiourea derivate N,N′-dimethyl-S-(2,3,4,5,6-pentabromobenzyl)- isothiouronium bromide (ZKK-3) against the T98G GBM cell line. ZKK-3 was applied at concentrations of 10, 25 and 50 µM, and cells were maintained under conditions of normoxia, anoxia, hypoxia, hyperbaric oxygen (HBO), hypoxia/hypoxia and hypoxia/HBO. The proliferation and viability of neoplastic cells, and protein expression levels of hypoxia-inducible factor 1α (HIF-1α), PKD1, phosphorylated (p)PKD1 (Ser 916) and pPKD1 (Ser 744/748) kinases were evaluated. Oxygen deficiency, particularly regarding hypoxia, could diminish the cytotoxic effect of ZKK-3 at 25 and 50 µM and improve T98G cell survival compared with normoxia. HBO significantly reduced cell proliferation and increased T98G cell sensitivity to ZKK-3 when compared with normoxia. HIF-1α expression levels were increased under hypoxia compared with normoxia and decreased under HBO compared with hypoxia/hypoxia at 0, 10 and 50 µM ZKK-3, suggesting that HBO improved oxygenation of the cells. ZKK-3 exhibited inhibitory activity against pPKD1 (Ser 916) kinase; however, the examined oxygen conditions did not appear to significantly influence the expression of this phosphorylated form in cells treated with the tested compound. Regarding pPKD1 (Ser 744/748), a significant difference in expression was observed only for cells treated with 10 µM ZKK-3 and hypoxia/hypoxia compared with normoxia. However, there were significant differences in the expression levels of both phosphorylated forms of PKD1 under different oxygen conditions in the controls. In conclusion, the combination of isothiourea derivatives and hyperbaric oxygenation appears to be a promising therapeutic approach for malignant glioma treatment.

Targeting JUN, CEBPB, and HDAC3: A Novel Strategy to Overcome Drug Resistance in Hypoxic Glioblastoma

Hypoxia is a predominant feature in glioblastoma (GBM) and contributes greatly to its drug resistance. However, the molecular mechanisms which are responsible for the development of the resistant phenotype of GBM under hypoxic conditions remain unclear. To analyze the key pathways promoting therapy resistance in hypoxic GBM, we utilized the U87-MG cell line as a human GBM cell model and the human brain HEB cell line as a non-neoplastic brain cell model. These cell lines were cultured in the presence of 21, 5, and 1% O2 for 24 h. We detected the changes in transcriptional profiling and analyzed the biological processes and functional interactions for the genes with different expression levels under different hypoxia conditions. The results indicated that those alterations of U87-MG cells presented specific transcriptional signature in response to diverse hypoxia levels. Gene ontology analysis revealed that the genes related to the DNA replication and cell cycle were suppressed, while the genes involved in tissue and system development to promote cancer development were activated following hypoxia. Moreover, functional interaction analysis suggested that the epigenetic regulator HDAC3 and the transcriptional factors CEBPB and JUN played a central role in organ and system developmental process pathway. Previous studies reported the global alterations caused by activation of HDAC3, CEBPB, and JUN could form the molecular basis of the resistance to chemotherapy and radiation therapy of hypoxic GBM. In our study, the significant growth inhibitory effect of temozolomide on hypoxic GBM cells could be promoted under downregulation of these genes. The experiment suggested that HDAC3, CEBPB, and JUN were closely involved in the drug-resistance phenotype of hypoxic GBM. In summary, we profiled the hypoxia-dependent changes in the transcriptome of the U87-MG cell line and the human brain cell line HEB to identify the transcriptional signatures of U87-MG cells and elucidate the role of hypoxia in the drug-resistant phenotype of GBM. Furthermore, we identified three key genes and explored their important roles in the drug resistance of hypoxic GBM.

Hypoxia-Induced Resistance to Chemotherapy in Cancer

A major barrier to the successful management of cancer is the development of resistance to therapy. Chemotherapy resistance can either be an intrinsic property of malignant cells developed prior to therapy, or acquired following exposure to anti-cancer drugs. Given the impact of drug resistance to the overall poor survival of cancer patients, there is an urgent need to better understand the molecular pathways regulating this malignant phenotype. In this chapter we describe some of the molecular pathways that contribute to drug resistance in cancer, the role of a microenvironment deficient in oxygen (hypoxia) in malignant progression, and how hypoxia can be a significant factor in the development of drug resistance. We conclude by proposing potential therapeutic approaches that take advantage of a hypoxic microenvironment to chemosensitize therapy-resistant tumours.

Autologous cytokine-induced killer cell immunotherapy may improve overall survival in advanced malignant melanoma patients

AIMS

Our study was conducted to explore the efficacy of autologous cytokine-induced killer (CIK) cells in patients with advanced malignant melanoma. Materials & Methods: Here we reviewed 113 stage IV malignant melanoma patients among which 68 patients received CIK cell immunotherapy alone, while 45 patients accepted CIK cell therapy combined with chemotherapy. Results: We found that the median survival time in CIK cell group was longer than the combined therapy group (21 vs 15 months, p = 0.07). In addition, serum hemoglobin level as well as monocyte proportion and lymphocyte count were associated with patients' survival time.

CONCLUSIONS

These indicated that CIK cell immunotherapy might extend survival time in advanced malignant melanoma patients. Furthermore, serum hemoglobin level, monocyte proportion and lymphocyte count could be prognostic indicators for melanoma.

Hyperbaric oxygen therapy as adjunctive strategy in treatment of glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most common type of malignant intracranial tumor in adults. Tumor tissue hypoxia, high mitotic rate, and rapid tumor spread account for its poor prognosis. Hyperbaric oxygen therapy (HBOT) may improve the sensitivity of radio-chemotherapy by increasing oxygen tension within the hypoxic regions of the neoplastic tissue. This review summarizes the research of HBOT applications within the context of experimental and clinical GBM. Limited clinical trials and preclinical studies suggest that radiotherapy immediately after HBOT enhances the effects of radiotherapy in some aspects. HBOT also is able to strengthen the anti-tumor effect of chemotherapy when applied together. Overall, HBOT is well tolerated in the GBM patients and does not significantly increase toxicity. However, HBOT applied by itself as curative strategy against GBM is controversial in preclinical studies and has not been evaluated rigorously in GBM patients. In addition to HBOT favorably managing the therapeutic resistance of GBM, future research needs to focus on the multimodal or cocktail approaches to treatment, as well as molecular strategies targeting GBM stem cells.

Quantitative analysis of the proliferative-to-invasive transition of hypoxic glioma cells

Impact of the proliferative-to-invasive transformation of glioma cells on the global growth kinetics of the tumor.

Change in 18F-Fluoromisonidazole PET Is an Early Predictor of the Prognosis in the Patients with Recurrent High-Grade Glioma Receiving Bevacizumab Treatment

Background

Bevacizumab (BEV), a humanized monoclonal antibody, become a currently important chemotherapeutic option for the patients with recurrent glioma. The aim of this retrospective study is to investigate whether ¹⁸F-Fluoromisonidazole (FMISO) PET have the potential to detect BEV-resistant gliomas in the early-stage.

Methods

We reviewed the FMISO PET and MRI appearances before and 3 to 4 courses after BEV treatment on 18 recurrent glioma patients. FMISO accumulation was assessed by visual inspection and semi-quantitative values which were tumor-to-normal (T/N) ratio and hypoxic volume. MRI responses were evaluated based on RANO (Response Assessment in Neuro-Oncology) criteria. The prognostic analysis was performed in relation to the response assessment by FMISO PET and MRI using overall survival (OS) after BEV application.

Results

After BEV application, MRI revealed partial response in 14 of 18 patients (78%), of which 9 patients also demonstrated decreased FMISO accumulation. These 9 patients (50%) were classified as “MRI-FMISO double responder”. As for the other 5 patients (28%), FMISO accumulation volumes increased or remained stable after BEV treatment although partial responses were achieved on MRI. Therefore, these cases were classified as “MRI-only responder”. The remaining 4 patients (22%) did not show treatment response on FMISO PET or MRI (“non-responder”). MRI-FMISO double responders showed significantly longer OS than that in other groups (median 12.4 vs 5.7 months; P < 0.001), whereas there were no overall survival difference between MRI-only responders and non-responders (median OS, 5.7 and 4.8 months; P = 0.58). Among the pre-treatment clinical factors, high FMISO T/N ratio was a significant prognostic factor of overall survival in these patients under the assessment of Cox proportional hazard model.

Conclusions

Recurrent gliomas with decreasing FMISO accumulation after short-term BEV application could derive a survival benefit from BEV treatment. Change in FMISO PET appearance can identify BEV-resistant gliomas in early-stage regardless of MRI findings in a comprehensible way.

Hyperbaric oxygen as an adjunctive therapy in treatment of malignancies, including brain tumours

Hyperbaric oxygen (HBO) therapy is widely used as an adjunctive treatment for various pathological states, predominantly related to hypoxic and/or ischaemic conditions. It also holds promise as an approach to overcoming the problem of oxygen deficiency in the poorly oxygenated regions of the neoplastic tissue. Occurrence of local hypoxia within the central areas of solid tumours is one of the major issues contributing to ineffective medical treatment. However, in anti-cancer therapy, HBO alone gives a limited curative effect and is typically not applied by itself. More often, HBO is used as an adjuvant treatment along with other therapeutic modalities, such as radio- and chemotherapy. This review outlines the existing data regarding the medical use of HBO in cancer treatment, with a particular focus on the use of HBO in the treatment of brain tumours. We conclude that the administration of HBO can provide many clinical benefits in the treatment of tumours, including management of highly malignant gliomas. Applied immediately before irradiation, it is safe and well tolerated by patients, causing rare and limited side effects. The results obtained with a combination of HBO/radiotherapy protocol proved to be especially favourable compared to radiation treatment alone. HBO can also increase the cytostatic effect of certain drugs, which may render standard chemotherapy more effective. The currently available data support the legitimacy of conducting further research on the use of HBO in the treatment of malignancies.

Ultrasound-mediated destruction of oxygen and paclitaxel loaded lipid microbubbles for combination therapy in hypoxic ovarian cancer cells

We synthesized oxygen and paclitaxel (PTX) loaded lipid microbubbles (OPLMBs) for ultrasound mediated combination therapy in hypoxic ovarian cancer cells. Our experiments successfully demonstrated that ultrasound induced OPLMBs destruction significantly enhanced the local oxygen release. We also demonstrated that OPLMBs in combination with ultrasound (300 kHz, 0.5 W/cm(2), 15s) yielded anti-proliferative activities of 52.8 ± 2.75% and cell apoptosis ratio of 35.25 ± 0.17% in hypoxic cells at 24h after the treatment, superior to other treatment groups such as PTX only and PTX-loaded MBs (PLMBs) with or without ultrasound mediation. RT-PCR and Western blot tests further confirmed the reduced expression of HIF-1α and MDR-1/P-gp after ultrasound mediation of OPLMBs. Our experiment suggests that ultrasound mediation of oxygen and drug-loaded MBs may be a useful method to overcome chemoresistance in the hypoxic ovarian cancer cells.

Repurposing some older drugs that cross the blood-brain barrier and have potential anticancer activity to provide new treatment options for glioblastoma

Glioblastoma is a brain neoplasm with limited 5-year survival rates. Developments of new treatment regimens that improve patient survival in patients with glioblastoma are needed. It is likely that a number of existing drugs used in other conditions have potential anticancer effects that offer significant survival benefit to glioblastoma patients. Identification of such drugs could provide a novel treatment paradigm.

A patient-specific computational model of hypoxia-modulated radiation resistance in glioblastoma using 18F-FMISO-PET

Glioblastoma multiforme (GBM) is a highly invasive primary brain tumour that has poor prognosis despite aggressive treatment. A hallmark of these tumours is diffuse invasion into the surrounding brain, necessitating a multi-modal treatment approach, including surgery, radiation and chemotherapy. We have previously demonstrated the ability of our model to predict radiographic response immediately following radiation therapy in individual GBM patients using a simplified geometry of the brain and theoretical radiation dose. Using only two pre-treatment magnetic resonance imaging scans, we calculate net rates of proliferation and invasion as well as radiation sensitivity for a patient's disease. Here, we present the application of our clinically targeted modelling approach to a single glioblastoma patient as a demonstration of our method. We apply our model in the full three-dimensional architecture of the brain to quantify the effects of regional resistance to radiation owing to hypoxia in vivo determined by [(18)F]-fluoromisonidazole positron emission tomography (FMISO-PET) and the patient-specific three-dimensional radiation treatment plan. Incorporation of hypoxia into our model with FMISO-PET increases the model-data agreement by an order of magnitude. This improvement was robust to our definition of hypoxia or the degree of radiation resistance quantified with the FMISO-PET image and our computational model, respectively. This work demonstrates a useful application of patient-specific modelling in personalized medicine and how mathematical modelling has the potential to unify multi-modality imaging and radiation treatment planning.

Hypoxia enhances migration and invasion in glioblastoma by promoting a mesenchymal shift mediated by the HIF1α-ZEB1 axis

Glioblastoma (GBM) is the most common brain tumor in adults and the mesenchymal GBM subtype was reported to be the most malignant, presenting severe hypoxia and necrosis. Here, we investigated the possible role of a hypoxic microenvironment for inducing a mesenchymal and invasive phenotype. The exposure of non-mesenchymal SNB75 and U87 cells to hypoxia induced a strong change in cell morphology that was accompanied by enhanced invasive capacity and the acquisition of mesenchymal marker expression. Further analyses showed the induction of HIF1α and HIF2α by hypoxia and exposure to digoxin, a cardiac glycoside known to inhibit HIF1/2 expression, was able to prevent hypoxia-induced mesenchymal transition. ShRNA-mediated knockdown of HIF1α, and not HIF2α, prevented this transition, as well as the knockdown of the EMT transcription factor ZEB1. We provide further evidence for a hypoxia-induced mesenchymal shift in GBM primary material by showing co-localization of GLUT1, ZEB1 and the mesenchymal marker YKL40 in hypoxic regions of the tumor. Collectively, our results identify a HIF1α-ZEB1 signaling axis that promotes hypoxia induced mesenchymal shift and invasion in GBM in a cell line dependent fashion.

Lower mean corpuscular hemoglobin concentration is associated with unfavorable prognosis of resected lung cancer

ABSTRACT 

Background: The association of preoperative red blood cell indexes in non-anemic patients undergoing lung resections for non-small-cell lung cancer with recurrence-free survival (RFS) and overall survival (OS) has never been investigated. Methods: We retrospectively examined the impact of preoperative red blood cell indexes on RFS and OS and the relationships between the indexes and clinicopathological factors in lung cancer. Results: A total of 649 patients were evaluated. The mean corpuscular hemoglobin concentration was showed as an independent prognostic factor in all patients for OS (hazard ratio [HR]: 0.697; 95% CI: 0.502–0.969; p = 0.032) and RFS (HR: 0.688; 95% CI: 0.519–0.914; p = 0.010). The mean corpuscular volume was an independent prognostic factor in all patients for OS (HR: 0.589; 95% CI: 0.380–0.912; p = 0.018), but not for RFS (HR: 0.684; 95% CI: 0.461–1.015; p = 0.059). Conclusion: In conclusion, the results of this study suggest that mean corpuscular hemoglobin concentration is an independent prognostic factor for OS and RFS in non-small-cell lung cancer.

Radiosensitization of malignant gliomas following intracranial delivery of paclitaxel biodegradable polymer microspheres

OBJECT

The aim of this study was to demonstrate that paclitaxel could function as a radiosensitizer for malignant glioma in vitro and in vivo.

METHODS

The radiosensitizing effect of paclitaxel was tested in vitro using the human U373MG and rat 9L glioma cell lines. Cell cycle arrest in response to paclitaxel exposure was quantified by flow cytometry. Cells were subsequently irradiated, and toxicity was measured using the clonogenic assay. In vivo studies were performed in Fischer 344 rats implanted with intracranial 9L gliosarcoma. Rats were treated with control polymer implants, paclitaxel controlled-release polymers, radiotherapy, or a combination of the 2 treatments. The study end point was survival.

RESULTS

Flow cytometry demonstrated G2-M arrest in both U373MG and 9L cells following 6-12 hours of paclitaxel exposure. The order in which the combination treatment was administered was significant. Exposure to radiation treatment (XRT) during the 6-12 hours after paclitaxel treatment resulted in a synergistic reduction in colony formation. This effect was greater than the effect from either treatment alone and was also greater than the effect of radiation exposure followed by paclitaxel. Rats bearing 9L gliosarcoma tumors treated with paclitaxel polymer administration followed by single-fraction radiotherapy demonstrated a synergistic improvement in survival compared with any other treatment, including radiotherapy followed by paclitaxel treatment. Median survival for control animals was 13 days; for those treated with paclitaxel alone, 21 days; for those treated with XRT alone, 21 days; for those treated with XRT followed by paclitaxel, 45 days; and for those treated with paclitaxel followed by XRT, more than 150 days (p < 0.0001).

CONCLUSIONS

These results indicate that paclitaxel is an effective radiosensitizer for malignant gliomas because it renders glioma cells more sensitive to ionizing radiation by causing G2-M arrest, and induces a synergistic response to chemoradiotherapy.

A high-throughput photodynamic therapy screening platform with on-chip control of multiple microenvironmental factors

We present a novel high-throughput microfluidic platform that enables the evaluation of the anticancer efficacy of photodynamic therapy (PDT) drugs over multiple microenvironmental factors. PDT is uniquely complex, originating from its dependence on three separate but essential elements: drug (also called photosensitizer), oxygen, and light. Thus, obtaining a reliable evaluation of PDT efficacy is highly challenging, requiring considerable effort and time to evaluate all three interdependent parameters. In this paper, we report a high-throughput efficacy screening platform that we implemented by developing microfluidic components that individually control basic PDT elements (photosensitizer concentrations, oxygen levels, and light fluence) and then integrating them into a single triple-layer device. The integrated microfluidic chip consists of an array of small compartments, each corresponding to a specific combination of these three variables. This allows for more than 1000 different conditions being tested in parallel. Cancer cells are cultured within the device, exposed to different PDT conditions, and then monitored for their viability using live/dead fluorescence staining. The entire screening assay takes only 1 hour, and the collected PDT outcomes (cell viability) for combinatorial screening are analysed and reported as traditional dose-response curves or 3D bubble charts using custom software. As a proof of concept, methylene blue is adopted as a photosensitizer and its drug efficacy on C6 glioma cells has been successfully evaluated for a total of 324 PDT conditions using the fabricated chip. This platform can facilitate not only the development of new photosensitizers but also the optimization of current PDT protocols.

A miR-297/hypoxia/DGK-α axis regulating glioblastoma survival

BACKGROUND

Despite advances in the treatment of the most aggressive form of brain tumor, glioblastoma, patient prognosis remains disappointing. This failure in treatment has been attributed to dysregulated oncogenic pathways, as observed in other tumors. We and others have suggested the use of microRNAs (miRs) as therapeutic tools able to target multiple pathways in glioblastoma.

METHODS

This work features PCR quantification of miRs and transient transfection of many glioblastoma cell lines with miRs, followed by cell number analysis, trypan blue staining, alamarBlue assay of cell viability, caspase-3/-7 activity assay, immunoblot of cleaved poly(ADP-ribose) polymerase and fluorescence activated cell sorting and imaging of apoptotic nuclei, cell invasion assays, MRIs of glioblastoma xenografts in mice using transiently transfected cells as well as posttumor treatment with lentiviral vector encoding miR-297, and analysis of miR-297 target diacylglycerol kinase (DGK)-α including immunoblot, 3'UTR luciferase activity, and rescue with DGK-α overexpression. Cell counts and DGK-α immunoblot were also analyzed in the context of hypoxia and with overexpression of heterogeneous ribonucleoprotein L (hnRNPL).

RESULTS

We identified miR-297 as a highly cytotoxic microRNA in glioblastoma, with minimal cytotoxicity to normal astrocytes. miR-297 overexpression reduced in vitro invasiveness and in vivo tumor formation. DGK-α is shown to be a miR-297 target with a critical role in miR-297 toxicity. In addition, hypoxia and its mediator hnRNPL upregulated DGK-α and buffered the cytotoxic effects of miR-297.

CONCLUSION

This work shows miR-297 as a novel and physiologic regulator of cancer cell survival, largely through targeting of DGK-α, and also indicates that hypoxia ameliorates miR-297 toxicity to cancer cells.

Effect of oxygen on multidrug resistance in the first trimester human placenta

INTRODUCTION

The multidrug resistance proteins, P-glycoprotein (P-gp, encoded by the ABCB1 gene) and breast cancer resistance protein (BCRP, encoded by ABCG2) are highly expressed in the first trimester placenta. These transporters protect the fetus from exposure to maternally derived toxins and xenobiotics. Since oxygen is a regulator of multidrug resistance in various tissues, we hypothesized that changes in oxygen tension alter placental ABCB1/P-gp and ABCG2/BCRP expression in the first trimester.

METHODS

Placental specimens were collected from first (n = 7), second (n = 5) and term pregnancies (n = 5). First trimester placental villous explants were incubated (24 or 48 h) in different oxygen tension (3-20%). ABCB1, ABCG2 and VEGFA mRNA expression levels were assessed by RT-PCR and protein was localized by IHC.

RESULTS

ABCB1 is expressed most highly in the first trimester placenta (p < 0.05), whereas ABCG2 expression does not change significantly over pregnancy. P-gp and BCRP staining is present in the syncytiotrophoblast and in cytotrophoblasts. ABCG2 mRNA is increased in hyperoxic (20%) conditions after 48 h (p < 0.05). In contrast, hypoxia (3%) did not change ABCB1 mRNA expression but significantly increased VEGFA mRNA (p < 0.05). Hypoxia resulted in increased BCRP staining in cytotrophoblasts and in the microvillous membrane of the syncytium. Whereas, hypoxia resulted in increased P-gp staining in proliferating cytotrophoblasts.

CONCLUSION

We conclude that placental multidrug resistance expression, specifically ABCG2, is regulated by oxygen tension in the first trimester. It is possible that changes in placental oxygen supply are capable of altering fetal drug exposure especially during early pregnancy.

The roles of hypoxia-inducible factors in regulating neural stem cells migration to glioma stem cells and determinating their fates

The mortality of patients with malignant gliomas remains high despite the advancement in multi-modal therapy including surgery, radio- and chemotherapy. Glioma stem cells (GSCs), sharing some characteristics with normal neural stem cells (NSCs), contribute to the cellular origin for primary gliomas and the recurrence of malignant gliomas after current conventional therapy. Accordingly, targeting GSCs proves to be a promising avenue of therapeutic intervention. The specific tropism of NSCs to GSCs provides a novel platform for targeted delivery of therapeutic agents. Tropism and mobilization of NSCs are enhanced by hypoxia through upregulating chemotactic cytokines and activating several signaling pathways. Moreover, hypoxia-inducible factors (HIFs) produced under hypoxic microenvironment of the stem cell niche play critical roles in the growth and stemness phenotypes regulation of both NSCs and GSCs. However, the definite cellular and molecular mechanisms of HIFs involvement in the process remain obscure. In this review, we focus on the pivotal roles of HIFs in migration of NSCs to GSCs and potential roles of HIFs in dictating the fates of migrated NSCs and targeted GSCs.

Development of (99m)Tc-N4-NIM for molecular imaging of tumor hypoxia

The nitro group of 2-nitroimidazole (NIM) enters the tumor cells and is bioreductively activated and fixed in the hypoxia cells. 1,4,8,11-tetraazacyclotetradecane (N4) has shown to be a stable chelator for ^99mTc. The present study was aimed to develop ^99mTc-cyclam-2-nitroimidazole (^99mTc-N4-NIM) for tumor hypoxia imaging. N4-NIM precursor was synthesized by reacting N4-oxalate and 1,3-dibromopropane-NIM, yielded 14% (total synthesis). Cell uptake of ^99mTc-N4-NIM and ^99mTc-N4 was obtained in 13762 rat mammary tumor cells and mesothelioma cells in 6-well plates. Tissue distribution of ^99mTc-N4-NIM was evaluated in breast-tumor-bearing rats at 0.5–4 hrs. Tumor oxygen tension was measured using an oxygen probe. Planar imaging was performed in the tumor-bearing rat and rabbit models. Radiochemical purity of ^99mTc-N4-NIM was >96% by HPLC. Cell uptake of ^99mTc-N4-NIM was higher than ^99mTc-N4 in both cell lines. Biodistribution of ^99mTc-N4-NIM showed increased tumor-to-blood and tumor-to-muscle count density ratios as a function of time. Oxygen tension in tumor tissue was 6–10 mmHg compared to 40–50 mmHg in normal muscle tissue. Planar imaging studies confirmed that the tumors could be visualized clearly with ^99mTc-N4-NIM in animal models. Efficient synthesis of N4-NIM was achieved. ^99mTc-N4-NIM is a novel hypoxic probe and may be useful in evaluating cancer therapy.

Sensitivity to cisplatin in primary cell lines derived from human glioma correlates with levels of EGR-1 expression

Background

Less than 30% of malignant gliomas respond to adjuvant chemotherapy. Here, we have asked whether variations in the constitutive expression of early-growth response factor 1 (EGR-1) predicted acute cytotoxicity and clonogenic cell death in vitro, induced by six different chemotherapics.

Materials and methods

Cytotoxicity assays were performed on cells derived from fresh tumor explants of 18 human cases of malignant glioma. In addition to EGR-1, tumor cultures were investigated for genetic alterations and the expression of cancer regulating factors, related to the p53 pathway.

Results

We found that sensitivity to cisplatin correlates significantly with levels of EGR-1 expression in tumors with wild-type p53/INK4a/p16 status.

Conclusion

Increased knowledge of the mechanisms regulating EGR-1 expression in wild-type p53/INK4a/p16 cases of glioma may help in the design of new chemotherapeutic strategies for these tumors.

Effects of hypoxia on expression of a panel of stem cell and chemoresistance markers in glioblastoma-derived spheroids

Tumor hypoxia has been attributed to play a crucial role in tumorigenesis and therapeutic resistance. Recently, it has been suggested that hypoxia leads to and maintains the undifferentiated state of tumor stem cells, thereby contributing to chemoresistance. The aim of the present study is to investigate the influence of hypoxia on the protein expression of a panel of stem cell and chemoresistance markers using in vivo-like multicellular tumor spheroids derived from a glioblastoma short-term culture with tumor stem cell properties (SJ-1) as well as a conventional glioblastoma cell line (U87). Spheroids were formed in 21% and 1% O(2) in serum-free medium. The immunohistochemical panel included hypoxia (HIF-1α, HIF-2α), proliferation (Ki-67), and stem cell markers (CD133, podoplanin, Bmi-1, nestin, Sox-2) as well as markers related to chemoresistance (MGMT, TIMP-1, Lamp-1, MRP1, MDR-1). As spheroids derived in hypoxia were smaller than in normoxia, a set of experiments was included in which the culturing time of hypoxic spheroids was extended to obtain equally sized spheroids. The results showed that expression of HIF-1α and HIF-2α was increased in hypoxia, whereas Ki-67 was reduced. Expression of stem cell markers CD133, podoplanin, Bmi-1, and nestin was increased in hypoxia, whereas Sox-2 was increased in SJ-1 only. TIMP-1 and Lamp-1 were increased in both SJ-1 and U87. In conclusion, the tumor cell phenotype related to stemness, and thereby potentially to chemoresistance, seems to depend on the oxygen tension, suggesting that development of therapeutic strategies targeting tumor stem cells should take oxygen tension into account.

Hypoxia-inducible factors regulate tumorigenic capacity of glioma stem cells

Glioblastomas are lethal cancers characterized by florid angiogenesis promoted in part by glioma stem cells (GSCs). Because hypoxia regulates angiogenesis, we examined hypoxic responses in GSCs. We now demonstrate that hypoxia-inducible factor HIF2alpha and multiple HIF-regulated genes are preferentially expressed in GSCs in comparison to non-stem tumor cells and normal neural progenitors. In tumor specimens, HIF2alpha colocalizes with cancer stem cell markers. Targeting HIFs in GSCs inhibits self-renewal, proliferation, and survival in vitro, and attenuates tumor initiation potential of GSCs in vivo. Analysis of a molecular database reveals that HIF2A expression correlates with poor glioma patient survival. Our results demonstrate that GSCs differentially respond to hypoxia with distinct HIF induction patterns, and HIF2alpha might represent a promising target for antiglioblastoma therapies.

Neural stem cell tropism to glioma: critical role of tumor hypoxia

Hypoxia is a critical aspect of the microenvironment in glioma and generally signifies unfavorable clinical outcome. Effective targeting of hypoxic areas in gliomas remains a significant therapeutic challenge. New therapeutic platforms using neural stem cells (NSC) for tumor-targeted drug delivery show promise in treatment of cancers that are refractory to traditional therapies. However, the molecular mechanisms of NSC targeting to hypoxic tumor areas are not well understood. Therefore, we investigated the role of hypoxia in directed migration of NSCs to glioma and identified the specific signaling molecules involved. Our data showed that hypoxia caused increased migration of human HB1.F3 NSCs to U251 human glioma-conditioned medium in vitro. In HB1.F3 NSCs, hypoxia led to up-regulation of CXCR4, urokinase-type plasminogen activator receptor (uPAR), vascular endothelial growth factor receptor 2 (VEGFR2), and c-Met receptors. Function-inhibiting antibodies to these receptors inhibited the migration of HB1.F3 cells to glioma-conditioned medium. Small interfering RNA knockdown of hypoxia-inducible factor-1alpha in glioma cells blocked the hypoxia-induced migration of NSCs, which was due to decreased expression of stromal cell-derived factor-1 (SDF-1), uPA, and VEGF in glioma cells. Our in vivo data provided direct evidence that NSCs preferentially distributed to hypoxic areas inside intracranial glioma xenografts, as detected by pimonidazole hypoxia probe, as well as to the tumor edge, and that both areas displayed high SDF-1 expression. These observations indicate that hypoxia is a key factor in determining NSC tropism to glioma and that SDF-1/CXCR4, uPA/uPAR, VEGF/VEGFR2, and hepatocyte growth factor/c-Met signaling pathways mediate increased NSC-to-glioma tropism under hypoxia. These results have significant implications for development of stem cell-mediated tumor-selective gene therapies.

Regional hypoxia in glioblastoma multiforme quantified with [18F]fluoromisonidazole positron emission tomography before radiotherapy: correlation with time to progression and survival

PURPOSE

Hypoxia is associated with resistance to radiotherapy and chemotherapy and activates transcription factors that support cell survival and migration. We measured the volume of hypoxic tumor and the maximum level of hypoxia in glioblastoma multiforme before radiotherapy with [(18)F]fluoromisonidazole positron emission tomography to assess their impact on time to progression (TTP) or survival.

EXPERIMENTAL DESIGN

Twenty-two patients were studied before biopsy or between resection and starting radiotherapy. Each had a 20-minute emission scan 2 hours after i.v. injection of 7 mCi of [(18)F]fluoromisonidazole. Venous blood samples taken during imaging were used to create tissue to blood concentration (T/B) ratios. The volume of tumor with T/B values above 1.2 defined the hypoxic volume (HV). Maximum T/B values (T/B(max)) were determined from the pixel with the highest uptake.

RESULTS

Kaplan-Meier plots showed shorter TTP and survival in patients whose tumors contained HVs or tumor T/B(max) ratios greater than the median (P < or = 0.001). In univariate analyses, greater HV or tumor T/B(max) were associated with shorter TTP or survival (P < 0.002). Multivariate analyses for survival and TTP against the covariates HV (or T/B(max)), magnetic resonance imaging (MRI) T1Gd volume, age, and Karnovsky performance score reached significance only for HV (or T/B(max); P < 0.03).

CONCLUSIONS

The volume and intensity of hypoxia in glioblastoma multiforme before radiotherapy are strongly associated with poorer TTP and survival. This type of imaging could be integrated into new treatment strategies to target hypoxia more aggressively in glioblastoma multiforme and could be applied to assess the treatment outcomes.

Hypoxia increases tumor cell shedding of MHC class I chain-related molecule: role of nitric oxide

The MHC class I chain-related (MIC) molecules play important roles in tumor immune surveillance through their interaction with the NKG2D receptor on natural killer and cytotoxic T cells. Thus, shedding of the MIC molecules from the tumor cell membrane represents a potential mechanism of escape from NKG2D-mediated immune surveillance. Tumor hypoxia is associated with a poor clinical outcome for cancer patients. We show that hypoxia contributes to tumor cell shedding of MIC through a mechanism involving impaired nitric oxide (NO) signaling. Whereas hypoxia increased MIC shedding in human prostate cancer cells, activation of NO signaling inhibited hypoxia-mediated MIC shedding. Similar to incubation in hypoxia, pharmacologic inhibition of endogenous NO signaling increased MIC shedding. Parallel studies showed hypoxia-mediated tumor cell resistance to lysis by interleukin 2-activated peripheral blood lymphocytes (PBL) and NO-mediated attenuation of this resistance to lysis. Inhibition of NO production also led to resistance to PBL-mediated lysis. Interference of MIC-NKG2D interaction with a blocking anti-MIC antibody abrogated the effect of hypoxia and NO signaling on tumor cell sensitivity to PBL-mediated lysis. Finally, continuous transdermal delivery of the NO mimetic glyceryl trinitrate (7.3 mug/h) attenuated the growth of xenografted MIC-expressing human prostate tumors. These findings suggest that the hypoxic tumor microenvironment contributes to resistance to immune surveillance and that activation of NO signaling is of potential use in cancer immunotherapy.

Hypoxia induces resistance to 5-fluorouracil in oral cancer cells via G(1) phase cell cycle arrest

Malignant tumors are exposed to various levels of hypoxic condition in vivo. It has been known that tumor cells under hypoxia are resistant to chemotherapies. To clarify the mechanism of the hypoxia-induced chemoresistance, we evaluated the effects of hypoxia on the resistance of oral squamous cell carcinoma (OSCC) cell lines to 5-fluorouracil (5-FU). OSCC cells were divided to two groups by the proliferation activity under hypoxic condition; hypoxia-resistant (HR) and hypoxia-sensitive (HS) cells. Growth of HS cells were inhibited by hypoxia and introduced to G(1) arrest in cell cycle. 5-FU effect on HS cell viability was markedly reduced in hypoxic condition without an induction of chemoresistant related protein, P-glycoprotein. However, proliferation, cell cycle, and 5-FU sensitivity of HR cells were not affected by hypoxia. Hypoxia-inducible factor (HIF)-1alpha was induced by hypoxia in all OSCC cell lines, but diminished in HS cells within 48h. Expression of p21 and p27 was strongly augmented and CyclinD expression was reduced by hypoxia in HS cells. However, the expression of these proteins was constitutive in HR cells during 48h hypoxic culture. Phosphorylation of mammalian target of rapamycin (mTOR) was reduced by hypoxia in HS cells. From these findings, we concluded that HS OSCC cells acquire 5-FU resistance under hypoxia by G(1)/S transition through an upregulation of cell cycle inhibitors.

Solid tumor physiology and hypoxia-induced chemo/radio-resistance: novel strategy for cancer therapy: nitric oxide donor as a therapeutic enhancer

Hypoxia exists in solid tumor tissues due to abnormal vasculature, vascular insufficiency, treatment or malignancy related anemia, and low intratumor blood flow. Hypoxic status in solid tumor promotes accumulation of hypoxia-inducible factor-1 alpha which is promptly degraded by proteasomal ubiquitination under normoxic conditions. However, under hypoxic conditions, the ubiquitination system for HIF-1 alpha is inhibited by inactivation of prolyl hydroxylase which is responsible for hydroxylation of proline in the oxygen-dependent degradation domain of HIF-1 alpha. HIF-1 alpha is an important transcriptional factor that codes for hundreds of genes involved in erythropoiesis, angiogenesis, induction of glycolytic enzymes in tumor tissues, modulation of cancer cell cycle, cancer proliferation, and cancer metastasis. Hypoxia and accumulation of HIF-1 alpha in solid tumor tissues have been reported to associate with resistance to chemotherapy, radiotherapy, and immunotherapy and poor prognosis. Production of vascular endothelial growth factor (VEGF) in cancer cells is regulated by the activated HIF-1 mediated system. An increase in VEGF levels subsequently induces HIF-1 alpha accumulation and promotes tumor metastasis by angiogenesis. Recently, angiogenesis targeting therapy using humanized VEGF antibody and VEGF receptor tyrosine kinase inhibitors have been used in solid cancer therapy. Nitric oxide (NO) is a unique chemical gaseous molecule that plays a role as a chemical messenger involved in vasodilator, neurotransmitter, and anti-platelet aggregation. In vivo, NO is produced and released from three different isoforms of NO synthase (NOS) and from exogenously administered NO donors. In cancer science, NO has been mainly discussed as an oncogenic molecule over the past decades. However, NO has recently been noted in cancer biology associated with cancer cell apoptosis, cancer cell cycle, cancer progression and metastasis, cancer angiogenesis, cancer chemoprevention, and modulator for chemo/radio/immuno-therapy. The presence and activities of all the three isoforms of NOS and were detected in cancer tissue components such as cancer cells, tumor-associated macrophages, and vascular endothelium. Overexpression of iNOS in cancer tissues has been reported to associate with poor prognosis in patients with cancers. On the other hand, NO donors such as nitroglycerin have been demonstrated to improve the effects of cancer therapy in solid cancers. Nitroglycerin has been used safely for a long time as a potent vasodilator for the treatment of ischemic heart diseases or heart failure. Therefore, we think highly of clinical use of nitroglycerin as a novel cancer therapy in combination with anticancer drugs for improvement of cancer therapeutic levels. In this review article, we demonstrate the unique physiological characteristics of malignant solid tumors, several factors in solid tumors resulting in resistance for cancer therapies, and the effects of NO from NOS or exogenous NO-donating drugs on malignant cells. Furthermore, we refer to promising therapeutic roles of NO and NO-donating drugs for novel treatments in solid tumors.

The Effects of Crinum asiaticum on the Apoptosis Induction and the Reversal of Multidrug Resistance in HL-60/MX2

The present study investigated the anti-proliferative and chemosensitizing effects of Crinum asiaticum var. japonicum against multi-drug resistant (MDR) cancer cells. The 80% methanol extract, chloroform (CHCI3) fraction and butanol (BuOH) fraction of C asiaticum inhibited the growth of mitoxantrone (MX) resistant HL-60 (HL-60/MX2) cells. When HL-60/MX2 cells were treated with the CHCI3 and BuOH fractions, DNA ladder and sub-G1 hypodiploid cells were observed. Furthermore, the fractions reduced Bcl-2 mRNA levels, whereas Bax mRNA levels were increased. These results suggest that the inhibitory effect of C. asiaticum on the growth of the HL-60/MX2 cells might arise from the induction of apoptosis. Treatment of HL-60/MX2 cells with the fractions markedly decreased the mRNA levels of the multi-drug resistance protein-1 and breast cancer resistance protein. The CHCI3 fraction and hexane fraction increased MX accumulation in HL-60/MX2 cells. These results imply that the CHCI3 fraction of C asiaticum plays a pivotal role as a chemosensitizer. We suggest that components of C asiaticum might have a therapeutic potential for the treatment of MDR leukemia.

Impact of hypoxic and acidic extracellular conditions on cytotoxicity of chemotherapeutic drugs

In the microenvironment of solid growing tumors, pronounced hypoxia or extracellular acidosis is commonly found. The aim of this study was the analysis of the cytotoxic effect of different chemotherapeutic agents (cisplatin, daunorubicin, docetaxel) under these conditions in vitro. Prostate carcinoma cells (R3327-AT1) were exposed to hypoxia (pO2 < 0.5 mmHg) or extracellular acidosis (pH = 6.6) for 6h. After 3h, cytotoxic drugs were added. The cytotoxic effect was assessed by measuring caspase 3-activity (apoptosis), LDH release (necrosis) and repopulation of the cells after chemotherapy (cell death). Compared to aerobic control conditions, severe hypoxia over 6 h per se led to a slight increase in apoptosis, necrosis and cell death. With all three chemotherapeutic agents, hypoxia led to a reduced (by approx. 25%) caspase 3-activity and a marked increase in necrosis. However, the overall cytotoxicity of the drug was not affected by O2-deficiency. By contrast, during extracellular acidosis, the cytotoxic effect of daunorubicin was reduced by 40%, preferentially due to a marked reduction in apoptosis. With cisplatin and docetaxel no change in overall cell death was detected. However, for daunorubicin the tumor-pH seems to have a strong impact on cytotoxicity. With this chemotherapeutic drug the therapeutic efficacy is markedly reduced in an acidotic environment.

Nitroglycerin treatment may enhance chemosensitivity to docetaxel and carboplatin in patients with lung adenocarcinoma

PURPOSE

Nitroglycerin may improve the response to chemotherapy in advanced non-small cell lung cancer. The effects and mechanisms of nitroglycerin on the enhancement of chemosensitivity to docetaxel and carboplatin regimen (DCb) in patients with lung adenocarcinoma have not been reported.

EXPERIMENTAL DESIGN

Seventeen patients with operable lung adenocarcinoma and stable angina pectoris were selected to investigate the effects of nitroglycerin on immunoreactivity for hypoxia-inducible factor 1alpha (HIF-1alpha), vascular endothelial growth factor (VEGF), P-glycoprotein (P-gp), the production of which is regulated by HIF-1, and p53 proteins in their resected tumor by semiquantitative immunohistochemical analyses. Eight of 17 patients were treated with nitroglycerin patches before operation, but 9 of 17 patients were not. Furthermore, to study the relationship between changes in plasma VEGF levels by nitroglycerin treatment and response to DCb, 29 patients with advanced lung adenocarcinoma were treated with nitroglycerin for 3 days before chemotherapy using DCb.

RESULTS

The rates of immunoreactive cells for HIF-1alpha, VEGF, and P-gp in tumor tissues treated with nitroglycerin were lower than those without nitroglycerin, but those for p53 were not different between those treated with and without nitroglycerin. Furthermore, the rates of immunoreactive cells for VEGF and P-gp proteins were significantly associated with those for HIF-1alpha in tumor tissue. The magnitude of decrease in plasma VEGF levels after treatment with nitroglycerin was significantly associated with response to DCb in patients with advanced lung adenocarcinoma.

CONCLUSIONS

Nitroglycerin treatment may improve response to DCb in patients with lung adenocarcinoma, partly through decreasing VEGF and P-gp production via reduction of HIF-1alpha.

Expression of autocrine motility factor mRNA is a poor prognostic factor in high-grade astrocytoma

It has been reported that tumor infiltration is correlated with the expression of autocrine motility factor (AMF) and its receptor 78 kDa glycoprotein (gp78). The purpose of the present study was to detect AMF and gp78 mRNA expression levels and their localization in high-grade astrocytomas (glioblastoma and anaplastic astrocytoma) and to determine whether AMF and gp78 are important prognostic factors. A total of 32 formalin-fixed and paraffin-embedded glioblastomas and 23 formalin-fixed and paraffin-embedded anaplastic astrocytomas was used. The expressions of AMF and gp78 mRNA were detected using the highly sensitive in situ hybridization method. The expression of AMF mRNA was detected in 27 of 32 glioblastomas (84.4%) and 11 of 23 anaplastic astrocytomas (47.8%). The positivity of AMF mRNA was significantly higher in glioblastomas than in anaplastic astrocytomas (P = 0.0094), but gp78 mRNA was detected in most cases and no statistical significance was observed. The overall survival of patients with AMF expression was significantly shorter than patients without AMF expression (P = 0.0175). In anaplastic astrocytomas, the overall survival of patients with AMF expression was also significantly shorter than in patients without AMF expression (P = 0.0058). This study demonstrated that AMF is a poor prognostic factor in high-grade astrocytomas.

Impact of extracellular acidity on the activity of P-glycoprotein and the cytotoxicity of chemotherapeutic drugs

The expression and activity of P-glycoprotein (pGP) play a role in the multidrug resistance of tumors. Because solid-growing tumors often show pronounced hypoxia or extracellular acidosis, this study attempted to analyze the impact of an acidic environment on the expression and activity of pGP and on the cytotoxicity of chemotherapeutic agents. For this, prostate carcinoma cells were exposed to an acidic extracellular environment (pH 6.6) for up to 24 hours. pGP activity was more than doubled after 3 to 6 hours of incubation in acidic medium, whereas cellular pGP expression remained constant, indicating that increased transport rate is the result of functional modulation. In parallel, the cytotoxic efficacy of daunorubicin showed pronounced reduction at low pH, an effect that was reversible on coincubation with a pGP inhibitor. A reduction of intracellular Ca2+ concentration by 35% under acidic conditions induced a higher transport rate of pGP, an effect comparable to that found on inhibition of protein kinase C (PKC). These data indicate that pGP activity is increased by low extracellular pH presumably as a result of lowered intracellular calcium levels and inhibition of PKC. These findings may explain the reduced cytotoxicity of chemotherapeutic agents in hypoxic/acidic tumors.

S-nitrosoglutathione and hypoxia-inducible factor-1 confer chemoresistance against carbamoylating cytotoxicity of BCNU in rat C6 glioma cells

BCNU (1,3-bis[2-chloroethyl]-1-nitrosourea) is the mainstay in glioblastoma multiform chemotherapy with only minimal effects. BCNU may kill tumor cells via carbamoylating cytotoxicity, which irreversibly inhibits glutathione reductase with resultant accumulation of oxidized form of glutathione causing oxidative stress. S-nitrosoglutathione (GSNO) is a product of glutathione and nitric oxide interaction. We report that GSNO formation may underlie carbamoylating chemoresistance mediated by activation of inducible nitric oxide synthase. Transactivation of hypoxia-inducible factor-1 (HIF-1)-responsive genes reduces oxidative stress caused by glutathione depletion. We also noted that preconditioning of C6 glioma cells to induce HIF-1 and its downstream genes confers chemoresistance against carbamoylating cytotoxicity of BCNU.

Hypoxia in head and neck cancer

A high level of hypoxia in solid tumours is an adverse prognostic factor for the poor outcome of cancer patients following treatment. This review describes the status of research into finding a practical method for measuring hypoxia and treating hypoxic tumours. The application of such methodology would enable the selection of head and neck cancer treatment based on an individual's tumour oxygenation status. This individualization would include the selection not only of surgery or radiotherapy, but also of novel hypoxia-modification strategies.

PET and planar imaging of tumor hypoxia with labeled metronidazole

RATIONALE AND OBJECTIVES

This study was aimed to develop 99mTc- and 68Ga-labeled metronidazole (MN) using ethylenedicysteine (EC) as a chelator and evaluate their potential use to assess tumor hypoxia.

MATERIALS AND METHODS

EC-MN was labeled with 99mTc in the presence of tin (II) chloride. Labeling EC-MN with 68Ga was achieved by adding 68GaCl3 (2 mCi with 3.4 microg cold GaCl3). In vitro cellular uptakes of 99mTc- and 68Ga-EC-MN were obtained in various types of tumor cells at 0.5-4 hours. Tissue distribution and PET imaging of 99mTc and 68Ga-EC-MN were evaluated in breast tumor-bearing rats at 0.5-4 hours. Tumor oxygen tension was measured using an oxygen probe.

RESULTS

There were similar cellular uptakes (2-10%) between 99mTc- and 68Ga-EC-MN at 0.5-4 hours. In vivo biodistribution of 99mTc- and 68Ga-EC-MN in breast tumor-bearing rats showed increased tumor-to-blood and tumor-to-muscle count density ratios as a function of time. Positron emission tomography images confirmed that the tumors could be visualized clearly with 68Ga-EC-MN. Oxygen tension in tumor tissue was determined to be 6-10 mm Hg compared with 40-50 mm Hg in normal muscle tissue.

CONCLUSIONS

The results indicated that it is feasible to use 99mTc- and 68Ga-EC-MN for assessment of tumor hypoxia. These agents may be useful in selecting and evaluating cancer therapy.

Interactions between hypoxia and epidermal growth factor receptor in non-small-cell lung cancer

Tumor hypoxia has been recognized to confer resistance to anticancer therapy since the early 20th century. More recently, its fundamental role in tumorigenesis has been established. Hypoxia-inducible factor (HIF)-1 has been identified as an important transcription factor that mediates the cellular response to hypoxia, promoting both cellular survival and apoptosis under different conditions. Increased tumor cell expression of this transcription factor promotes tumor growth in vivo and is associated with a worse prognosis in patients with non-small-cell lung cancer (NSCLC) undergoing tumor resection. The epidermal growth factor receptor (EGFR) promotes tumor cell proliferation and angiogenesis and inhibits apoptosis. Epidermal growth factor receptor expression increases in a stepwise manner during tumorigenesis and is overexpressed in > 50% of NSCLC tumors. This review discusses the reciprocal relationship between tumor cell hypoxia and EGFR. Recent studies suggest that hypoxia induces expression of EGFR and its ligands. In return, EGFR might enhance the cellular response to hypoxia by increasing expression of HIF-1a and so act as a survival factor for hypoxic cancer cells. Immunohistochemical studies on a series of resected NSCLC tumors add weight to this contention by demonstrating a close association between expression of EGFR, HIF-1a, and 1 of HIF-1's target proteins, carbonic anhydrase IX. In this article we discuss emerging treatment strategies for NSCLC that target HIF-1, HIF-1 transcriptional targets, and EGFR.

A cDNA-microarray analysis of camptothecin resistance in glioblastoma cell lines

Chemotherapy, as generally available, is of a limited value in curing malignant brain tumors (gliomas), which often develop resistance to drugs, becoming completely unresponsive to any standard therapeutic approach. Camptothecins, a family of topoisomerase I inhibitor drugs, represent a new promising treatment strategy and are currently under evaluation for testing the clinical efficacy. We selected a CPT-resistant sub-line (U87CPT-R) from U87-MG grade III-IV astrocytoma cells, and compared the expression profile of the two cell lines by cDNA-microarray, as a preliminary screening of the molecular mechanisms involved in the acquisition of CPT resistance in glioma cells. The relevant role of IL-1 beta overproduction as well as a generalised up-regulation of genes implicated in angiogenesis and inflammatory response are discussed in details.

Randomized phase II trial comparing nitroglycerin plus vinorelbine and cisplatin with vinorelbine and cisplatin alone in previously untreated stage IIIB/IV non-small-cell lung cancer

PURPOSE

To investigate the efficacy and safety of nitroglycerin plus vinorelbine and cisplatin in patients with previously untreated stage IIIB/IV non-small-cell lung cancer (NSCLC) as the experimental arm for the next phase III trial.

PATIENTS AND METHODS

One hundred twenty patients with stage IIIB/IV NSCLC were randomly assigned to vinorelbine 25 mg/m2 on days 1 and 8 and cisplatin 80 mg/m2 on day 1, with transdermally applied nitroglycerin (25 mg/patient daily for 5 days; arm A) or with placebo patch (arm B) every 3 weeks for a maximum of four cycles in a double-blind and controlled trial. Primary efficacy end points were the best confirmed response rate and time to disease progression (TTP).

RESULTS

The response rate in arm A (72%; 43 of 60 patients) was significantly higher than that for patients in arm B (42%; 25 of 60 patients; P < .001). Median TTP in arm A was longer than that in arm B (327 v 185 days). No severe adverse effect was recognized for either arm. The rate of grade 1 to 2 headache in arm A (30%; 18 of 60 patients) was significantly higher than that in arm B (2%; one of 60 patients; P < .001, chi(2) test).

CONCLUSION

Use of nitroglycerin combined with vinorelbine and cisplatin may improve overall response and TTP in patients with stage IIIB/IV NSCLC. The arm A regimen is being evaluated in a large phase III trial.

Serum hemoglobin level determined at the first presentation is a poor prognostic indicator in patients with lung cancer

OBJECTIVES

Anemia is observed in various malignancies including lung cancer and is recently considered to be a poor prognostic indicator. We investigated whether there is a correlation between anemia, other clinicopathologic factors, and survival.

METHODS

We retrospectively examined the clinical records of 611 patients with lung cancer.

RESULTS

Of those, 298 (48.8%) patients had anemia at the time of their first visit to our hospital. There was a significant correlation between anemia and age (p=0.0006) or ECOG performance status (p=0.0002), however, there was no correlation of anemia with gender, histological type, clinical stage, or serum level of lactate dehydrogenase. Survival was significantly shorter in 298 patients with anemia (median survival time (MST): 7.5 months) compared with 313 patients without anemia (MST: 11.8 months, p<0.0001). Multivariate analysis of prognostic factors using the Cox proportional hazards model revealed that anemia appeared to be an independent prognostic indicator.

CONCLUSION

Anemia observed at the first presentation is an independent poor prognostic indicator in patients with lung cancer.

Pre-chemotherapy hemoglobin levels and survival in patients with advanced epithelial ovarian cancer who received a first-line taxane/platinum-based regimen: Results of a multicenter retrospective Italian study

OBJECTIVE

The aim of this retrospective multicenter study was to assess whether the pre-chemotherapy hemoglobin levels have any impact on the clinical outcome of patients with advanced epithelial ovarian cancer who received a first-line taxane/platinum-based regimen.

METHODS

The study was conducted on 315 patients who underwent initial surgery followed by taxane/platinum-based chemotherapy for FIGO stage IIc-IV epithelial ovarian cancer. All the patients had ECOG performance status 0-1 at presentation. The median follow-up of survivors was 36 months (range, 6-120 months).

RESULTS

The 25%, 50%, and 75% quantiles of hemoglobin levels before starting first-line chemotherapy were 10.2, 11.4, and 12.3 g/dl, respectively. Residual disease after initial surgery (>1 cm versus </= 1 cm, P = 0.0013) was the only independent prognostic variable for overall survival. Conversely, hemoglobin levels (<10.2 g/dl versus 10.2-11.4 g/dl versus 11.5-12.3 g/dl versus >12.3 g/dl) were inversely related to overall survival at univariate (P = 0.03) but not at multivariate analysis.

CONCLUSIONS

This investigation showed that hemoglobin levels before starting first-line taxane/platinum-based chemotherapy are not an independent prognostic factor for overall survival in patients with advanced epithelial ovarian cancer.

c-Jun NH2-Terminal Kinase Activation Contributes to Hypoxia-Inducible Factor 1α–Dependent P-Glycoprotein Expression in Hypoxia

We previously have shown that hypoxia increases the expression of P-glycoprotein, which in turn increases tumor cell capacity to actively extrude chemotherapeutic agents and may contribute to tumor drug resistance. This event is mediated through the hypoxia-inducible factor (HIF-1). Here, we investigated the role of the stress-activated protein kinase c-Jun NH(2)-terminal kinase (JNK) in the signaling mechanisms underlying these events. Hypoxia activates JNK activity in vitro and in vivo. Overexpression of mitogen-activated protein kinase (MAPK) kinase kinase (MEKK-1), which preferentially activates JNK, mimics, in a nonadditive way, hypoxia-induced activity of the MDR1 promoter and expression of MDR1 mRNA and P-glycoprotein. Furthermore, the JNK inhibitor SP600125 selectively and specifically inhibits hypoxia- and MEKK-1-induced MDR1 promoter activity in a dose-dependent manner. JNK inhibition also reversed hypoxia- and MEKK-1-induced activity of an HIF-1-dependent reporter gene. MEKK-1-induced MDR1 expression depends on a functional HIF-1 binding site (hypoxia-responsive element). Hypoxia- but not cobalt chloride-dependent HIF-1-DNA binding and transcriptional activation was inhibited by SP600125, indicating that hypoxia-induced signaling to HIF-1 depends on JNK activation. Because it has been reported that reactive oxygen species are increased in hypoxia and related to JNK activation, we investigated their role in signaling this response. Whereas exogenous addition of H(2)O(2) was sufficient to activate JNK, reactive oxygen species scavengers were without effect on hypoxia-induced JNK or HIF-1 activation. Thus, hypoxia-elicited MDR1 expression, which depends on HIF-1 activation, depends at least in part on signaling via activation of JNK. Furthermore, these events are independent of the generation of reactive oxygen intermediates. Thus, JNK may represent a therapeutic target in the prevention of tumor resistance to chemotherapeutic treatment.

Differential responsiveness among "high risk" pediatric brain tumors in a pilot study of dose-intensive induction chemotherapy

BACKGROUND

These factors have been predictive for progressive disease on therapy (PDOT) among pediatric brain tumors: >1.5 cm(2) unresectable tumor, glioblastoma, supratentorial primitive neuroectodermal tumor, and metastatic medulloblastoma (MBL). This pilot study sought to correlate cytoreductive response with progression free survival.

PROCEDURES

Four courses of cisplatinum, cyclophosphamide, etoposide, and vincristine preceded hyperfractionated radiotherapy (RT). Maintenance chemotherapy consisted of eight cycles of carboplatin, etoposide, and vincristine. Biopsy specimens were immunohistochemically studied for labeling index, hypoxia, and multidrug resistance proteins.

RESULTS

Twenty newly diagnosed patients [nine primitive neuroectodermal tumors/MBL, one choroid plexus carcinoma, eight malignant gliomas, and two anaplastic ependymomas] were treated. Ten patients, who required neuraxis irradiation, constituted the "PNET" group. These demonstrated five complete and one partial response (PR), with an estimated median progression free survival of 44 months and median survival in excess of 53 months. Patients treated with involved field irradiation were designated the "Glioma" group. Induction chemotherapy produced partial and minor responses (MRs) among 5/10. Their estimated median progression free survival was 6.9 months (P = 0.035 relative to the PNET) with a median survival of 10.7 months (P = 0.04). Age, labeling index, the presence of hypoxia, and Pgp/MDR1 expression failed to discriminate between the two groups.

CONCLUSIONS

This induction regimen produced a cytoreductive response in 6/10 and achieved a significant improvement in progression free survival among 7/10 in the PNET group. Unfortunately, responses among Glioma patients did not translate into durable control. Expression of the biologic factors was similar between both groups and did not correlate with diagnosis or response.

Carbamoylating chemoresistance induced by cobalt pretreatment in C6 glioma cells: putative roles of hypoxia-inducible factor-1

1. We tested whether pretreatment of reagents known to induce hypoxia-inducible factor-1 (HIF-1) may confer chemoresistance against cytotoxicity of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) to rat C6 glioma cells. We also studied which cytotoxic mechanism(s) of chloroethylnitrosoureas could be neutralized by cobalt preconditioning. 2. Preconditioning of rat C6 glioma cells with cobalt chloride (300 microm, 2 h) induced HIF-1 binding activity based on electrophoretic mobility shift assay (EMSA). Results from Western blotting confirmed a heightened HIF-1alpha level upon cobalt chloride exposure (300-400 microm, 2 h). Cobalt chloride (300 microm) pretreatment for 2 h substantially neutralized BCNU toxicity, leading to increases in glioma cell survival based on MTT assay. In addition, pre-exposure of C6 cells with desferrioxamine (DFO; 400 microm, 3 h), an iron chelator known to activate HIF-1, also induced HIF-1 binding and rendered the glioma cells resistant to cytotoxicity of BCNU. 3. Pre-incubation with cobalt chloride abolished the cytotoxicity of several carbamoylating agents including 2-chloroethyl isocyanate and cyclohexyl isocyanate, the respective carbamoylating metabolites of BCNU and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea. The protective effect of cobalt exposure, however, was not observed when cells were challenged with alkylating agents including temozolomide. 4. Cadmium chloride (50 microm) effectively reversed cobalt-induced HIF-1 activation. Correspondingly, cadmium chloride suppressed carbamoylating chemoresistance mediated by cobalt chloride pretreatment. Furthermore, both double-stranded oligodeoxynucleotide (ODN) decoy with HIF-1 cognate sequence and antisense phosphorothioate ODNs against HIF-1alpha partially abolished the carbamoylating chemoresistance associated with cobalt preconditioning. 5. Our results suggest that cobalt- or DFO-preconditioning may enhance glioma carbamoylating chemoresistance that is dependent, at least in part, on induction of HIF-1.