Acute hypoxia enhances spontaneous lymph node metastasis in an orthotopic murine model of human cervical carcinoma

Optical redox ratio identifies metastatic potential-dependent changes in breast cancer cell metabolism

The development of prognostic indicators of breast cancer metastatic risk could reduce the number of patients receiving chemotherapy for tumors with low metastatic potential. Recent evidence points to a critical role for cell metabolism in driving breast cancer metastasis. Endogenous fluorescence intensity of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) can provide a label-free method for assessing cell metabolism. We report the optical redox ratio of FAD/(FAD + NADH) of four isogenic triple-negative breast cancer cell lines with varying metastatic potential. Under normoxic conditions, the redox ratio increases with increasing metastatic potential (168FARN>4T07>4T1), indicating a shift to more oxidative metabolism in cells capable of metastasis. Reoxygenation following acute hypoxia increased the redox ratio by 43 ± 9% and 33 ± 4% in the 4T1 and 4T07 cells, respectively; in contrast, the redox ratio decreased 14 ± 7% in the non-metastatic 67NR cell line. These results demonstrate that the optical redox ratio is sensitive to the metabolic adaptability of breast cancer cells with high metastatic potential and could potentially be used to measure dynamic functional changes that are indicative of invasive or metastatic potential.

The role of hypoxia in cancer progression, angiogenesis, metastasis, and resistance to therapy

Hypoxia is a non-physiological level of oxygen tension, a phenomenon common in a majority of malignant tumors. Tumor-hypoxia leads to advanced but dysfunctional vascularization and acquisition of epithelial-to-mesenchymal transition phenotype resulting in cell mobility and metastasis. Hypoxia alters cancer cell metabolism and contributes to therapy resistance by inducing cell quiescence. Hypoxia stimulates a complex cell signaling network in cancer cells, including the HIF, PI3K, MAPK, and NFĸB pathways, which interact with each other causing positive and negative feedback loops and enhancing or diminishing hypoxic effects. This review provides background knowledge on the role of tumor hypoxia and the role of the HIF cell signaling involved in tumor blood vessel formation, metastasis, and development of the resistance to therapy. Better understanding of the role of hypoxia in cancer progression will open new windows for the discovery of new therapeutics targeting hypoxic tumor cells and hypoxic microenvironment.

Development of a mathematical model to estimate intra-tumor oxygen concentrations through multi-parametric imaging

Background

Tumor hypoxia is involved in every stage of solid tumor development: formation, progression, metastasis, and apoptosis. Two types of hypoxia exist in tumors—chronic hypoxia and acute hypoxia. Recent studies indicate that the regional hypoxia kinetics is closely linked to metastasis and therapeutic responses, but regional hypoxia kinetics is hard to measure. We propose a novel approach to determine the local pO₂ by fusing the parameters obtained from in vivo functional imaging through the use of a modified multivariate Krogh model.

Methods

To test our idea and its potential to translate into an in vivo setting through the use of existing imaging techniques, simulation studies were performed comparing the local partial oxygen pressure (pO₂) from the proposed multivariate image fusion model to the referenced pO₂ derived by Green’s function, which considers the contribution from every vessel segment of an entire three-dimensional tumor vasculature to profile tumor oxygen with high spatial resolution.

Results

pO₂ derived from our fusion approach were close to the referenced pO₂ with regression slope near 1.0 and an r² higher than 0.8 if the voxel size (or the spatial resolution set by functional imaging modality) was less than 200 μm. The simulation also showed that the metabolic rate, blood perfusion, and hemoglobin concentration were dominant factors in tissue oxygenation. The impact of the measurement error of functional imaging to the pO₂ precision and accuracy was simulated. A Gaussian error function with FWHM equal to 20 % of blood perfusion or fractional vascular volume measurement contributed to average 7 % statistical error in pO₂.

Conclusion

The simulation results indicate that the fusion of multiple parametric maps through the biophysically derived mathematical models can monitor the intra-tumor spatial variations of hypoxia in tumors with existing imaging methods, and the potential to further investigate different forms of hypoxia, such as chronic and acute hypoxia, in response to cancer therapies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12938-016-0235-5) contains supplementary material, which is available to authorized users.

Tumor-associated Lymphatic Endothelial Cells Promote Lymphatic Metastasis By Highly Expressing and Secreting SEMA4C

PURPOSE

Lymphatic vessels are mainly regarded as passive conduits for the dissemination of cancer cells. In this study, we investigate whether and how the tumor-associated lymphatic vessels may play an active role in tumor metastasis.

EXPERIMENTAL DESIGN

In situ laser capture microdissection of lymphatic vessels followed by cDNA microarray analysis was used to determine the expression profiling of lymphatic endothelial cells (LEC). Gene expression levels and activity of signaling pathways were measured by real-time RT-PCR, ELISA, or immunoblotting. Lymphangiogenesis was assessed by IHC. Lymph node metastasis was measured using fluorescence imaging. The effects of SEMA4C on lymphangiogenesis in vitro were evaluated using migration assay and tube-formation assay of LECs.

RESULTS

Tumor-associated LECs are molecularly and functionally different from their normal counterparts. In addition to expressing high levels of membrane-bound SEMA4C, tumor-associated LECs also produced soluble SEMA4C (sSEMA4C). Increased serum sSEMA4C was detected in patients with breast cancer and cervical cancer. Patients with metastasis had much higher levels of serum sSEMA4C. sSEMA4C promoted lymphangiogenesis by activating PlexinB2-ERBB2 signaling in LECs, and promoted the proliferation and migration of tumor cells by activating PlexinB2-MET signaling, thus promoting lymphatic metastasis. Although the SEMA4C signaling pathways differ between LECs and tumor cells, RHOA activation was necessary for the effects of SEMA4C in both types of cells.

CONCLUSIONS

Tumor-associated LECs produce sSEMA4C to promote lymphatic metastasis of tumors. Our results suggest that SEMA4C and RHOA might be potential therapeutic targets, and that higher serum sSEMA4C could be a marker for breast cancer and cervical cancer. Clin Cancer Res; 23(1); 214-24. ©2016 AACR.

Cycling hypoxia: A key feature of the tumor microenvironment

A compelling body of evidence indicates that most human solid tumors contain hypoxic areas. Hypoxia is the consequence not only of the chaotic proliferation of cancer cells that places them at distance from the nearest capillary but also of the abnormal structure of the new vasculature network resulting in transient blood flow. Hence two types of hypoxia are observed in tumors: chronic and cycling (intermittent) hypoxia. Most of the current work aims at understanding the role of chronic hypoxia in tumor growth, response to treatment and metastasis. Only recently, cycling hypoxia, with spatial and temporal fluctuations in oxygen levels, has emerged as another key feature of the tumor environment that triggers different responses in comparison to chronic hypoxia. Either type of hypoxia is associated with distinct effects not only in cancer cells but also in stromal cells. In particular, cycling hypoxia has been demonstrated to favor, to a higher extent than chronic hypoxia, angiogenesis, resistance to anti-cancer treatments, intratumoral inflammation and tumor metastasis. These review details these effects as well as the signaling pathway it triggers to switch on specific transcriptomic programs. Understanding the signaling pathways through which cycling hypoxia induces these processes that support the development of an aggressive cancer could convey to the emergence of promising new cancer treatments.

Cathepsin L in tumor angiogenesis and its therapeutic intervention by the small molecule inhibitor KGP94

A significant proportion of breast cancer patients harbor clinically undetectable micrometastases at the time of diagnosis. If left untreated, these micro-metastases may lead to disease relapse and possibly death. Hence, there is significant interest in the development of novel anti-metastatic agents that could also curb the growth of pre-established micrometastases. Like primary tumor, the growth of metastases also is driven by angiogenesis. Although the role of cysteine protease Cathepsin L (CTSL) in metastasis associated tumor cell functions such as migration and invasion is well recognized, its role in tumor angiogenesis remains less explored. The present study examines the contribution of CTSL to breast cancer angiogenesis and evaluates the anti-angiogenic efficacy of CTSL inhibitor KGP94. CTSL semi-quantitative RT-PCR analysis on breast tissue panels revealed significant upregulation of CTSL in breast cancer patients which strongly correlated with increased relapse and metastatic incidence and poor overall survival. Preclinically, CTSL ablation using shRNA or KGP94 treatment led to a significant reduction in MDA-MB-231 tumor cell induced angiogenesis in vivo. In-vitro assessments demonstrated a significant decrease in various angiogenic properties such as endothelial cell sprouting, migration, invasion, tube formation and proliferation in the presence of KGP94. Microarray analyses revealed a significant upregulation of cell cycle related genes by CTSL. Western blot analyses further confirmed upregulation of members of the cyclin family by CTSL. Collectively, these data indicate that CTSL is an important contributor to tumor angiogenesis and that the CTSL inhibition may have therapeutic utility in the treatment of breast cancer patients.

Early diagnosis of lymph node metastasis: Importance of intranodal pressures

Regional lymph node status is an important prognostic indicator of tumor aggressiveness. However, early diagnosis of metastasis using intranodal pressure, at a stage when lymph node size has not changed significantly, has not been investigated. Here, we use an MXH10/Mo-lpr/lpr mouse model of lymph node metastasis to show that intranodal pressure increases in both the subiliac lymph node and proper axillary lymph node, which are connected by lymphatic vessels, when tumor cells are injected into the subiliac lymph node to induce metastasis to the proper axillary lymph node. We found that intranodal pressure in the subiliac lymph node increased at the stage when metastasis was detected by in vivo bioluminescence, but when proper axillary lymph node volume (measured by high-frequency ultrasound imaging) had not increased significantly. Intravenously injected liposomes, encapsulating indocyanine green, were detected in solid tumors by in vivo bioluminescence, but not in the proper axillary lymph node. Basic blood vessel and lymphatic channel structures were maintained in the proper axillary lymph node, although sinus histiocytosis was detected. These results show that intranodal pressure in the proper axillary lymph node increases at early stages when metastatic tumor cells have not fully proliferated. Intranodal pressure may be a useful parameter for facilitating early diagnosis of lymph node metastasis.

Measurement of Tumor Hypoxia in Patients with Advanced Pancreatic Cancer Based on 18F-Fluoroazomyin Arabinoside Uptake

Pancreatic cancers are thought to be unusually hypoxic, which might sensitize them to drugs that are activated under hypoxic conditions. In order to develop this idea in the clinic, a minimally invasive technique for measuring the oxygenation status of pancreatic cancers is needed.

METHODS

We tested the potential for minimally invasive imaging of hypoxia in pancreatic cancer patients, using the 2-nitroimidazole PET tracer (18)F-fluoroazomycin arabinoside (or (18)F-1-α-D-[5-fluoro-5-deoxyarabinofuranosyl]-2-nitroimidazole [(18)F-FAZA]). Dynamic and static scans were obtained in 21 patients with either locally advanced or metastatic disease. The hypoxic fraction was determined in the 2-h static scans as the percentage of voxels with SUVs more than 3 SDs from the mean values obtained for skeletal muscle.

RESULTS

Hypoxia was detected in 15 of 20 evaluable patients, with the hypoxic fraction ranging from less than 5% to greater than 50%. Compartmental analysis of the dynamic scans allowed us to approximate the tumor perfusion as mL/min/g of tissue, a value that is independent of the extent of hypoxia derived from tracer uptake in the 2-h static scan. There was no significant correlation between tumor perfusion and hypoxia; nor did we see an association between tumor volume and hypoxia.

CONCLUSION

Although pancreatic cancers can be highly hypoxic, a substantial proportion appears to be well oxygenated. Therefore, we suggest that a minimally invasive technique such as the one described in this study be used for patient stratification in future clinical trials of hypoxia-targeting agents.

Cycling hypoxia induces chemoresistance through the activation of reactive oxygen species-mediated B-cell lymphoma extra-long pathway in glioblastoma multiforme

BACKGROUND

Cycling hypoxia is a well-recognized phenomenon within animal and human solid tumors. It contributes to the resistance to cytotoxic therapies through anti-apoptotic effects. However, the mechanism underlying cycling hypoxia-mediated anti-apoptosis remains unclear.

METHODS

Reactive oxygen species (ROS) production, activation of the hypoxia-inducible factor-1 alpha (HIF-1α) and nuclear factor-κB (NF-κB) signaling pathways, B-cell lymphoma extra-long (Bcl-xL) expression, caspase activation, and apoptosis in in vitro hypoxic stress-treated glioblastoma cells or tumor hypoxic cells derived from human glioblastoma xenografts were determined by in vitro ROS analysis, reporter assay, western blotting analysis, quantitative real-time PCR, caspase-3 activity assay, and annexin V staining assay, respectively. Tempol, a membrane-permeable radical scavenger, Bcl-xL knockdown, and specific inhibitors of HIF-1α and NF-κB were utilized to explore the mechanisms of cycling hypoxia-mediated resistance to temozolomide (TMZ) in vitro and in vivo and to identify potential therapeutic targets.

RESULTS

Bcl-xL expression and anti-apoptotic effects were upregulated under cycling hypoxia in glioblastoma cells concomitantly with decreased responses to TMZ through ROS-mediated HIF-1α and NF-κB activation. Tempol, YC-1 (HIF-1 inhibitor), and Bay 11-7082 (NF-κB inhibitor) suppressed the cycling hypoxia-mediated Bcl-xL induction in vitro and in vivo. Bcl-xL knockdown and Tempol treatment inhibited cycling hypoxia-induced chemoresistance. Moreover, Tempol treatment of intracerebral glioblastoma-bearing mice combined with TMZ chemotherapy synergistically suppressed tumor growth and increased survival rate.

CONCLUSIONS

Cycling hypoxia-induced Bcl-xL expression via ROS-mediated HIF-1α and NF-κB activation plays an important role in the tumor microenvironment-promoted anti-apoptosis and chemoresistance in glioblastoma. Thus, ROS blockage may be an attractive therapeutic strategy for tumor microenvironment-induced chemoresistance.

The role of hypoxia in cancer progression, angiogenesis, metastasis, and resistance to therapy

Hypoxia is a non-physiological level of oxygen tension, a phenomenon common in a majority of malignant tumors. Tumor-hypoxia leads to advanced but dysfunctional vascularization and acquisition of epithelial-to-mesenchymal transition phenotype resulting in cell mobility and metastasis. Hypoxia alters cancer cell metabolism and contributes to therapy resistance by inducing cell quiescence. Hypoxia stimulates a complex cell signaling network in cancer cells, including the HIF, PI3K, MAPK, and NFĸB pathways, which interact with each other causing positive and negative feedback loops and enhancing or diminishing hypoxic effects. This review provides background knowledge on the role of tumor hypoxia and the role of the HIF cell signaling involved in tumor blood vessel formation, metastasis, and development of the resistance to therapy. Better understanding of the role of hypoxia in cancer progression will open new windows for the discovery of new therapeutics targeting hypoxic tumor cells and hypoxic microenvironment.

Obstructive sleep apnea and cancer: effects of intermittent hypoxia?

Obstructive sleep apnea (OSA) is a common disorder characterized by pauses in regular breathing. Apneic episodes lead to recurrent hypoxemia-reoxygenation cycles with concomitant cellular intermittent hypoxia. Studies suggest that intermittent hypoxia in OSA may influence tumorigenesis. This review presents recent articles on the potential role of OSA in cancer development. Relevant research has focused on: molecular pathways mediating the influence of intermittent hypoxia on tumor physiology, animal and epidemiological human studies linking OSA and cancer. Current data relating OSA to risk of neoplastic disease remain scarce, but recent studies reveal the potential for a strong relation. More work is, therefore, needed on the impact of OSA on many cancer-related aspects. Results may offer enlightenment for improved cancer diagnosis and treatment.

A Review of Current Animal Models for the Study of Cervical Dysplasia and Cervical Carcinoma

Cancer research has long relied on animal models for the study of disease mechanisms and new therapeutics. Future cancer treatments are likely to rely heavily on patient-derived xenograft models to develop novel treatments and tailor regimens to individual patient needs. However, specific models for cervical cancer and cervical dysplasia are limited. Only 3 models have been described in the published literature. A transgenic model for cervical cancer has allowed for the study of the differential contributions of the human papillomavirus 16 proteins E6 and E7 during oncogenesis. This model has also shown dysplasia development, although this has received little attention. A patient-derived tumor xenograft model where cervical cancer tissue is transplanted to the subcutaneous and orthotopic sites has been described. Here we review the reported transgenic and xenograft models, their strengths and limitations, and highlight the potential for the development of improved models to study cervical neoplasia.

Prognostic factors in patients with locally advanced head and neck cancer treated with concurrent radiochemotherapy

PURPOSE

This study was undertaken to evaluate the association of individual parameters and outcome in patients with unresectable locally advanced head and neck cancer treated with radiochemotherapy.

MATERIALS AND METHODS

We retrospectively reviewed data from 126 patients treated in our Institution between 1998 and 2010 for a locally advanced head and neck cancer. Sixteen individual parameters were evaluated for association with specific outcomes such as overall survival, persistence of disease, disease-specific survival and disease-free survival.

RESULTS

Six factors influenced overall survival on Kaplan-Meier survival analysis and on univariate Cox regression analysis: smoking, body mass index, site, haemoglobin (Hb) nadir, total dose of radiotherapy and comorbidities. On a multivariate logistic model with stepwise selection, comorbidities, body mass index, total dose and site maintained significance. A significant association for persistence of disease was found with smoking, Hb nadir and site of cancer on univariate and multivariate analysis. Disease-free survival was correlated with performance status, Hb nadir and comorbidities using Kaplan-Meier survival analysis and on univariate Cox regression analysis. Only performance status maintained the significance on multivariate analysis. Disease-specific survival was correlated with five parameters: body mass index, site, Hb nadir, therapy interruption and total dose; on multivariate analysis, Hb nadir, therapy interruption and site maintained a statistically significant association.

CONCLUSIONS

Hb nadir during treatment, body mass index, smoking, stage, comorbidities and performance status are prognostic factors of outcome and response to radical treatment with radiochemotherapy.

Prodding the Beast: Assessing the Impact of Treatment-Induced Metastasis

The arsenal of treatments for most cancers fit broadly into the categories of surgery, chemotherapy, radiation, and targeted therapy. All represent proven and successful strategies, yet each can trigger local (tumor) and systemic (host) processes that elicit unwanted, often opposing, influences on cancer growth. Under certain conditions, nearly all cancer treatments can facilitate metastatic spread, often in parallel (and sometimes in clear contrast) with tumor reducing benefits. The paradox of treatment-induced metastasis (TIM) is not new. Supporting preclinical studies span decades, but are often overlooked. With recent evidence of prometastatic effects following treatment with targeted agents blocking the tumor microenvironment, a closer inspection of this literature is warranted. The TIM phenomena may diminish the impact of effective therapies and play a critical role in eventual resistance. Alternatively, it may simply exemplify the gap between animal and human studies, and therefore have little impact for patient disease and treatment. This review will focus on the preclinical model systems used to evaluate TIM and explore the mechanisms that influence overall treatment efficacy. Understanding the role of TIM in established and emerging drug treatment strategies may help provide rationales for future drug combination approaches with antimetastatic agents to improve outcomes and reduce resistance.

Significance of Polypyrimidine Tract-Binding Protein 1 Expression in Colorectal Cancer

Polypyrimidine tract-binding protein (PTBP1) is an RNA-binding protein with various molecular functions related to RNA metabolism and a major repressive regulator of alternative splicing, causing exon skipping in numerous alternatively spliced pre-mRNAs. Here, we have investigated the role of PTBP1 in colorectal cancer. PTBP1 expression levels were significantly overexpressed in cancerous tissues compared with corresponding normal mucosal tissues. We also observed that PTBP1 expression levels, c-MYC expression levels, and PKM2:PKM1 ratio were positively correlated in colorectal cancer specimens. Moreover, PTBP1 expression levels were positively correlated to poor prognosis and lymph node metastasis. In analyses of colorectal cancer cells using siRNA for PTBP1, we observed that PTBP1 affects cell invasion, which was partially correlated to CD44 splicing, and this correlation was also confirmed in clinical samples. PTBP1 expression also affected anchorage-independent growth in colorectal cancer cell lines. PTBP1 expression also affected cell proliferation. Using time-lapse imaging analysis, PTBP1 was implicated in prolonged G2-M phase in HCT116 cells. As for the mechanism of prolonged G2-M phase in HCT116 siPTBP1 cells, Western blotting revealed that PTBP1 expression level was correlated to CDK11(p58) expression level, which was reported to play an important role on progression to complete mitosis. These findings indicated that PTBP1 is a potential therapeutic target for colorectal cancer.

Modulation of the tumor vasculature and oxygenation to improve therapy

The tumor microenvironment is increasingly recognized as a major factor influencing the success of therapeutic treatments and has become a key focus for cancer research. The progressive growth of a tumor results in an inability of normal tissue blood vessels to oxygenate and provide sufficient nutritional support to tumor cells. As a consequence the expanding neoplastic cell population initiates its own vascular network which is both structurally and functionally abnormal. This aberrant vasculature impacts all aspects of the tumor microenvironment including the cells, extracellular matrix, and extracellular molecules which together are essential for the initiation, progression and spread of tumor cells. The physical conditions that arise are imposing and manifold, and include elevated interstitial pressure, localized extracellular acidity, and regions of oxygen and nutrient deprivation. No less important are the functional consequences experienced by the tumor cells residing in such environments: adaptation to hypoxia, cell quiescence, modulation of transporters and critical signaling molecules, immune escape, and enhanced metastatic potential. Together these factors lead to therapeutic barriers that create a significant hindrance to the control of cancers by conventional anticancer therapies. However, the aberrant nature of the tumor microenvironments also offers unique therapeutic opportunities. Particularly interventions that seek to improve tumor physiology and alleviate tumor hypoxia will selectively impair the neoplastic cell populations residing in these environments. Ultimately, by combining such therapeutic strategies with conventional anticancer treatments it may be possible to bring cancer growth, invasion, and metastasis to a halt.

Cellular and molecular mechanisms underlying oxygen-dependent radiosensitivity

Molecular oxygen has long been recognized as a powerful radiosensitizer that enhances the cell-killing efficiency of ionizing radiation. Radiosensitization by oxygen occurs at very low concentrations with the half-maximum radiosensitization at approximately 3 mmHg. However, robust hypoxia-induced signal transduction can be induced at <15 mmHg and can elicit a wide range of cellular responses that will affect therapy response as well as malignant progression. Great strides have been made, especially since the 1990s, toward identification and characterization of the oxygen-regulated molecular pathways that affect tumor response to ionizing radiation. In this review, we will discuss the current advances in our understanding of oxygen-dependent molecular modification and cellular signal transduction and their impact on tumor response to therapy. We will specifically address mechanistic distinctions between radiobiological hypoxia (0-3 mmHg) and pathological hypoxia (3-15 mmHg). We also propose a paradigm that hypoxia increases radioresistance by maintaining the cancer stem cell phenotype.

Tumor interstitial fluid pressure-a link between tumor hypoxia, microvascular density, and lymph node metastasis

High microvascular density (MVD) in the primary tumor has been shown to be associated with increased incidence of lymph node metastases and poor clinical outcome. Other investigations have revealed that a large fraction of hypoxic tissue in the primary tumor is associated with metastatic disease and impaired survival. These data are apparently incompatible because tumor hypoxia is primarily a consequence of poor oxygen supply caused by an inadequate vasculature with increased intervessel distances. Here, we provide an explanation of these observations. Human melanoma xenografts were used as preclinical cancer models. Tumors that metastasized to lymph nodes showed higher interstitial fluid pressure (IFP) than those that did not metastasize, and compared with tumors with low IFP, tumors with high IFP showed large hypoxic fractions centrally, high MVD in the periphery, high peritumoral density of lymphatics, and elevated expression of vascular endothelial growth factor A (VEGF-A) and VEGF-C. Significant correlations were found between peripheral MVD and central hypoxia, and lymph node metastasis was associated with high values of both parameters. These findings suggest that the outcome of cancer may be associated with both high MVD and extensive hypoxia in the primary tumor. We propose that proangiogenic factors are upregulated in the tumor center and that the outward interstitial fluid flow caused by the elevated IFP transports these factors to the tumor surface where they evoke hemangiogenesis and lymphangiogenesis, and consequently, that the IFP serves as a link between tumor hypoxia, peripheral tumor hemangiogenesis, peritumoral lymphangiogenesis, and lymph node metastasis.

Establishment of orthotopic primary cervix cancer xenografts

Standard treatment for women who are diagnosed with stage IIB through IVA cervical cancer consists of cisplatin-based chemotherapy and radiation. Current options for patients with recurrent and metastatic disease are limited, and their median overall survival is <12 months. To date, biologic therapy has had little impact on survival, so identification of potential new targets is urgently required to develop novel therapeutic strategies. Developing relevant animal models for human cervix cancer is important to further enhance our understanding of the characteristics of these tumors and for identification and assessment of novel therapies. We have established a panel of orthotopically passaged xenografts (OCICx) by implanting cervix tumor pieces from patient biopsies directly into the cervix of mice. The tumors have been passaged up to five generations, were characterized histologically for tumor and stromal content and, where possible, related to similar measurements in the original patient biopsy. The tumors were found to metastasize to the para-aortic lymphnodes allowing assessment of their metastatic potential. Preliminary studies demonstrate aberrant expression of genes in the Hedgehog (Hh) pathway in the xenografts similar to findings in primary cervix cancers. The OCICx xenografts represent unique models to test strategies for targeting essential pathways in cervix cancer and metastasis.

The unfolded protein response potentiates epithelial-to-mesenchymal transition (EMT) of gastric cancer cells under severe hypoxic conditions

The hypoxic condition occurs in most types of solid tumors and has been shown to be associated with the metastatic ability of gastric cancer. A previous study has demonstrated that hypoxia might stimulate epithelial-to-mesenchymal transition (EMT) of gastric cancer cells. Nevertheless, the mechanism has not yet been completely understood. In the current study, the human gastric cancer cell lines HGC27 and MGC803 were presented to normoxic (21 % O2), hypoxic (1 % O2) or severe hypoxic (0.1 % O2) conditions for 24 h. We found that hypoxia exposure induced EMT of gastric cancer cells, which was promoted by severe hypoxia condition. Meanwhile, expressions of PERK, ATF4 and ATF6 proteins were elevated in cells under conditions of severe hypoxia but not by normoxia or hypoxia. Knockdown of PERK, ATF4 or ATF6 impeded EMT of gastric cancer cells induced by severe hypoxia. Furthermore, severe hypoxia exposure extremely boosted the expression of TGF-β, which was blocked by the knockdown of PERK, ATF4 or ATF6 expression. Additionally, we found that TGF-β release caused by hypoxia is facilitated by elevated UPR proteins and led to the activation of Smad2/3 and PI3K/Akt signaling. Our data suggest that UPR potentiates the EMT of gastric cancer cells under conditions of severe hypoxia.

Hypoxia promotes stem cell phenotypes and poor prognosis through epigenetic regulation of DICER

MicroRNAs are small regulatory RNAs that post transcriptionally control gene expression. Reduced expression of DICER, the enzyme involved in microRNA processing, is frequently observed in cancer and is associated with poor clinical outcome in various malignancies. Yet, the underlying mechanisms are not well understood. Here we identify tumour hypoxia as a regulator of DICER expression in large cohorts of breast cancer patients. We show that DICER expression is suppressed by hypoxia through an epigenetic mechanism that involves inhibition of oxygen-dependent H3K27me3 demethylases KDM6A/B and results in silencing of the DICER promoter. Subsequently, reduced miRNA processing leads to derepression of the miR-200 target ZEB1, stimulates the epithelial to mesenchymal transition and ultimately results in the acquisition of stem cell phenotypes in human mammary epithelial cells. Our study uncovers a previously unknown relationship between oxygen-sensitive epigenetic regulators, miRNA biogenesis and tumour stem cell phenotypes that may underlie poor outcome in breast cancer.

Targeting tumour hypoxia to prevent cancer metastasis. From biology, biosensing and technology to drug development: the METOXIA consortium

The hypoxic areas of solid cancers represent a negative prognostic factor irrespective of which treatment modality is chosen for the patient. Still, after almost 80 years of focus on the problems created by hypoxia in solid tumours, we still largely lack methods to deal efficiently with these treatment-resistant cells. The consequences of this lack may be serious for many patients: Not only is there a negative correlation between the hypoxic fraction in tumours and the outcome of radiotherapy as well as many types of chemotherapy, a correlation has been shown between the hypoxic fraction in tumours and cancer metastasis. Thus, on a fundamental basis the great variety of problems related to hypoxia in cancer treatment has to do with the broad range of functions oxygen (and lack of oxygen) have in cells and tissues. Therefore, activation-deactivation of oxygen-regulated cascades related to metabolism or external signalling are important areas for the identification of mechanisms as potential targets for hypoxia-specific treatment. Also the chemistry related to reactive oxygen radicals (ROS) and the biological handling of ROS are part of the problem complex. The problem is further complicated by the great variety in oxygen concentrations found in tissues. For tumour hypoxia to be used as a marker for individualisation of treatment there is a need for non-invasive methods to measure oxygen routinely in patient tumours. A large-scale collaborative EU-financed project 2009-2014 denoted METOXIA has studied all the mentioned aspects of hypoxia with the aim of selecting potential targets for new hypoxia-specific therapy and develop the first stage of tests for this therapy. A new non-invasive PET-imaging method based on the 2-nitroimidazole [(18)F]-HX4 was found to be promising in a clinical trial on NSCLC patients. New preclinical models for testing of the metastatic potential of cells were developed, both in vitro (2D as well as 3D models) and in mice (orthotopic grafting). Low density quantitative real-time polymerase chain reaction (qPCR)-based assays were developed measuring multiple hypoxia-responsive markers in parallel to identify tumour hypoxia-related patterns of gene expression. As possible targets for new therapy two main regulatory cascades were prioritised: The hypoxia-inducible-factor (HIF)-regulated cascades operating at moderate to weak hypoxia (<1% O(2)), and the unfolded protein response (UPR) activated by endoplasmatic reticulum (ER) stress and operating at more severe hypoxia (<0.2%). The prioritised targets were the HIF-regulated proteins carbonic anhydrase IX (CAIX), the lactate transporter MCT4 and the PERK/eIF2α/ATF4-arm of the UPR. The METOXIA project has developed patented compounds targeting CAIX with a preclinical documented effect. Since hypoxia-specific treatments alone are not curative they will have to be combined with traditional anti-cancer therapy to eradicate the aerobic cancer cell population as well.

CXCR4 as biomarker for radioresistant cancer stem cells

PURPOSE

Radioresistance of cancer cells remains a fundamental barrier for maximum efficient radiotherapy. Tumor heterogeneity and the existence of distinct cell subpopulations exhibiting different genotypes and biological behaviors raise difficulties to eradicate all tumorigenic cells. Recent evidence indicates that a distinct population of tumor cells, called cancer stem cells (CSC), is involved in tumor initiation and recurrence and is a putative cause of tumor radioresistance. There is an urgent need to identify the intrinsic molecular mechanisms regulating the generation and maintenance of resistance to radiotherapy, especially within the CSC subset. The chemokine C-X-C motif receptor 4 (CXCR4) has been found to be a prognostic marker in various types of cancer, being involved in chemotaxis, stemness and drug resistance. The interaction of CXCR4 with its ligand, the chemokine C-X-C motif ligand 12 (CXCL12), plays an important role in modulating the tumor microenvironment, angiogenesis and CSC niche. Moreover, the therapeutic inhibition of the CXCR4/CXCL12 signaling pathway is sensitizing the malignant cells to conventional anti-cancer therapy.

CONTENT

Within this review we are summarizing the role of the CXCR4/CXCL12 axis in the modulation of CSC properties, the regulation of the tumor microenvironment in response to irradiation, therapy resistance and tumor relapse.

CONCLUSION

In light of recent findings, the inhibition of the CXCR4/CXCL12 signaling pathway is a promising therapeutic option to refine radiotherapy.

A microfluidic device to study cancer metastasis under chronic and intermittent hypoxia

Metastatic cancer cells must traverse a microenvironment ranging from extremely hypoxic, within the tumor, to highly oxygenated, within the host's vasculature. Tumor hypoxia can be further characterized by regions of both chronic and intermittent hypoxia. We present the design and characterization of a microfluidic device that can simultaneously mimic the oxygenation conditions observed within the tumor and model the cell migration and intravasation processes. This device can generate spatial oxygen gradients of chronic hypoxia and produce dynamically changing hypoxic microenvironments in long-term culture of cancer cells.

Intermittent hypoxia effect on osteoclastogenesis stimulated by neuroblastoma cells

Background

Neuroblastoma is the most common extracranial pediatric solid tumor. Intermittent hypoxia, which is characterized by cyclic periods of hypoxia and reoxygenation, has been shown to positively modulate tumor development and thereby induce tumor growth, angiogenic processes, and metastasis. Bone is one of the target organs of metastasis in advanced neuroblastoma Neuroblastoma cells produce osteoclast-activating factors that increase bone resorption by the osteoclasts. The present study focuses on how intermittent hypoxia preconditioned SH-SY5Y neuroblastoma cells modulate osteoclastogenesis in RAW 264.7 cells compared with neuroblastoma cells grown at normoxic conditions.

Methods

We inhibited HIF-1α and HIF-2α in neuroblastoma SH-SY5Y cells by siRNA/shRNA approaches. Protein expression of HIF-1α, HIF-2α and MAPKs were investigated by western blotting. Expression of osteoclastogenic factors were determined by real-time RT-PCR. The influence of intermittent hypoxia and HIF-1α siRNA on migration of neuroblastoma cells and in vitro differentiation of RAW 264.7 cells were assessed. Intratibial injection was performed with SH-SY5Y stable luciferase-expressing cells and in vivo bioluminescence imaging was used in the analysis of tumor growth in bone.

Results

Upregulation of mRNAs of osteoclastogenic factors VEGF and RANKL was observed in intermittent hypoxia-exposed neuroblastoma cells. Conditioned medium from the intermittent hypoxia-exposed neuroblastoma cells was found to enhance osteoclastogenesis, up-regulate the mRNAs of osteoclast marker genes including TRAP, CaSR and cathepsin K and induce the activation of ERK, JNK, and p38 in RAW 264.7 cells. Intermittent hypoxia-exposed neuroblastoma cells showed an increased migratory pattern compared with the parental cells. A significant increase of tumor volume was found in animals that received the intermittent hypoxia-exposed cells intratibially compared with parental cells.

Conclusions

Intermittent hypoxic exposure enhanced capabilities of neuroblastoma cells in induction of osteoclast differentiation in RAW 264.7 cells. Increased migration and intratibial tumor growth was observed in intermittent hypoxia-exposed neuroblastoma cells compared with parental cells.

SIX1 promotes tumor lymphangiogenesis by coordinating TGFβ signals that increase expression of VEGF-C

Lymphatic vessels are one of the major routes for the dissemination of cancer cells. Malignant tumors release growth factors such as VEGF-C to induce lymphangiogenesis, thereby promoting lymph node metastasis. Here, we report that sine oculis homeobox homolog 1 (SIX1), expressed in tumor cells, can promote tumor lymphangiogenesis and lymph node metastasis by coordinating with TGFβ to increase the expression of VEGF-C. Lymphangiogenesis and lymph node metastasis in cervical cancer were closely correlated with higher expression of SIX1 in tumor cells. By enhancing VEGF-C expression in tumor cells, SIX1 could augment the promoting effect of tumor cells on the migration and tube formation of lymphatic endothelial cells (LEC) in vitro and lymphangiogenesis in vivo. SIX1 enhanced TGFβ-induced activation of SMAD2/3 and coordinated with the SMAD pathway to modulate VEGF-C expression. Together, SIX1 and TGFβ induced much higher expression of VEGF-C in tumor cells than each of them alone. Despite its effect in promoting VEGF-C expression, TGFβ could inhibit lymphangiogenesis by directly inhibiting tube formation by LECs. However, the increased production of VEGF-C not only directly promoted migration and tube formation of LECs but also thwarted the inhibitory effect of TGFβ on LECs. That is, tumor cells that expressed high levels of SIX1 could promote lymphangiogenesis and counteract the negative effects of TGFβ on lymphangiogenesis by increasing the expression of VEGF-C. These findings provide new insights into tumor lymphangiogenesis and the various roles of TGFβ signaling in tumor regulation. Our results also suggest that SIX1/TGFβ might be a potential therapeutic target for preventing lymph node metastasis of tumor.

Global gene expression profiling in three tumor cell lines subjected to experimental cycling and chronic hypoxia

Hypoxia is one of the most important features of the tumor microenvironment, exerting an adverse effect on tumor aggressiveness and patient prognosis. Two types of hypoxia may occur within the tumor mass, chronic (prolonged) and cycling (transient, intermittent) hypoxia. Cycling hypoxia has been shown to induce aggressive tumor cell phenotype and radioresistance more significantly than chronic hypoxia, though little is known about the molecular mechanisms underlying this phenomenon. The aim of this study was to delineate the molecular response to both types of hypoxia induced experimentally in tumor cells, with a focus on cycling hypoxia. We analyzed in vitro gene expression profile in three human cancer cell lines (melanoma, ovarian cancer, and prostate cancer) exposed to experimental chronic or transient hypoxia conditions. As expected, the cell-type specific variability in response to hypoxia was significant. However, the expression of 240 probe sets was altered in all 3 cell lines. We found that gene expression profiles induced by both types of hypoxia were qualitatively similar and strongly depend on the cell type. Cycling hypoxia altered the expression of fewer genes than chronic hypoxia (6,132 vs. 8,635 probe sets, FDR adjusted p<0.05), and with lower fold changes. However, the expression of some of these genes was significantly more affected by cycling hypoxia than by prolonged hypoxia, such as IL8, PLAU, and epidermal growth factor (EGF) pathway-related genes (AREG, HBEGF, and EPHA2). These transcripts were, in most cases, validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Our results indicate that experimental cycling hypoxia exerts similar, although less intense effects, on the examined cancer cell lines than its chronic counterpart. Nonetheless, we identified genes and molecular pathways that seem to be preferentially regulated by cyclic hypoxia.

Imaging tumor hypoxia to advance radiation oncology

SIGNIFICANCE

Most solid tumors contain regions of low oxygenation or hypoxia. Tumor hypoxia has been associated with a poor clinical outcome and plays a critical role in tumor radioresistance.

RECENT ADVANCES

Two main types of hypoxia exist in the tumor microenvironment: chronic and cycling hypoxia. Chronic hypoxia results from the limited diffusion distance of oxygen, and cycling hypoxia primarily results from the variation in microvessel red blood cell flux and temporary disturbances in perfusion. Chronic hypoxia may cause either tumor progression or regressive effects depending on the tumor model. However, there is a general trend toward the development of a more aggressive phenotype after cycling hypoxia. With advanced hypoxia imaging techniques, spatiotemporal characteristics of tumor hypoxia and the changes to the tumor microenvironment can be analyzed.

CRITICAL ISSUES

In this review, we focus on the biological and clinical consequences of chronic and cycling hypoxia on radiation treatment. We also discuss the advanced non-invasive imaging techniques that have been developed to detect and monitor tumor hypoxia in preclinical and clinical studies.

FUTURE DIRECTIONS

A better understanding of the mechanisms of tumor hypoxia with non-invasive imaging will provide a basis for improved radiation therapeutic practices.

Vaginal delivery of paclitaxel via nanoparticles with non-mucoadhesive surfaces suppresses cervical tumor growth

Local delivery of chemotherapeutics in the cervicovaginal tract using nanoparticles may reduce adverse side effects associated with systemic chemotherapy, while improving outcomes for early-stage cervical cancer. It is hypothesized here that drug-loaded nanoparticles that rapidly penetrate cervicovaginal mucus (CVM) lining the female reproductive tract will more effectively deliver their payload to underlying diseased tissues in a uniform and sustained manner compared with nanoparticles that do not efficiently penetrate CVM. Paclitaxel-loaded nanoparticles are developed, composed entirely of polymers used in FDA-approved products, which rapidly penetrate human CVM and provide sustained drug release with minimal burst effect. A mouse model is further employed with aggressive cervical tumors established in the cervicovaginal tract to compare paclitaxel-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (conventional particles, or CP) and similar particles coated with Pluronic F127 (mucus-penetrating particles, or MPP). CP are mucoadhesive and, thus, aggregated in mucus, while MPP achieve more uniform distribution and close proximity to cervical tumors. Paclitaxel-MPP suppress tumor growth more effectively and prolong median survival of mice compared with unencapsulated paclitaxel or paclitaxel-CP. Histopathological studies demonstrate minimal toxicity to the cervicovaginal epithelia, suggesting paclitaxel-MPP may be safe for intravaginal use. These results demonstrate the in vivo advantages of polymer-based MPP for treatment of tumors localized to a mucosal surface.

Measuring tumor cycling hypoxia and angiogenesis using a side-firing fiber optic probe

Hypoxia and angiogenesis can significantly influence the efficacy of cancer therapy and the behavior of surviving tumor cells. There is a growing demand for technologies to measure tumor hypoxia and angiogenesis temporally in vivo to enable advances in drug development and optimization. This paper reports the use of frequency-domain photon migration with a side-firing probe to quantify tumor oxygenation and hemoglobin concentrations in nude rats bearing human head/neck tumors administered with carbogen gas, cycling hypoxic gas or just room air. Significant increase (with carbogen gas breathing) or decrease (with hypoxic gas breathing) in tumor oxygenation was observed. The trend in tumor oxygenation during forced cycling hypoxia (CH) followed that of the blood oxygenation measured with a pulse oximeter. Natural CH was also observed in rats under room air. The studies demonstrated the potential of the technology for longitudinal monitoring of tumor CH during tumor growth or in response to therapy.

Defining normoxia, physoxia and hypoxia in tumours-implications for treatment response

Tumour hypoxia is increasingly recognized as a major deleterious factor in cancer therapies, as it compromises treatment and drives malignant progression. This review seeks to clarify the oxygen levels that are pertinent to this issue. It is argued that normoxia (20% oxygen) is an extremely poor comparator for "physoxia", i.e. the much lower levels of oxygen universally found in normal tissues, which averages about 5% oxygen, and ranges from about 3% to 7.4%. Importantly, it should be recognized that the median oxygenation in untreated tumours is significantly much lower, falling between approximately 0.3% and 4.2% oxygen, with most tumours exhibiting median oxygen levels <2%. This is partially dependent on the tissue of origin, and it is notable that many prostate and pancreatic tumours are profoundly hypoxic. In addition, therapy can induce even further, often unrecognized, changes in tumour oxygenation that may vary longitudinally, increasing or decreasing during treatment in ways that are not always predictable. Studies that fail to take cognizance of the actual physiological levels of oxygen in tissues (approximately 5%) and tumours (approximately 1%) may fail to identify the real circumstances driving tumour response to treatment and/or malignant progression. This can be of particular importance in genetic studies in vitro when comparison to human tumours is required.

Characterization of metastasis formation and virotherapy in the human C33A cervical cancer model

More than 90% of cancer mortalities are due to cancer that has metastasized. Therefore, it is crucial to intensify research on metastasis formation and therapy. Here, we describe for the first time the metastasizing ability of the human cervical cancer cell line C33A in athymic nude mice after subcutaneous implantation of tumor cells. In this model, we demonstrated a steady progression of lumbar and renal lymph node metastases during tumor development. Besides predominantly occurring lymphatic metastases, we visualized the formation of hematogenous metastases utilizing red fluorescent protein (RFP) expressing C33A-RFP cells. RFP positive cancer cells were found migrating in blood vessels and forming micrometastases in lungs of tumor-bearing mice. Next, we set out to analyze the influence of oncolytic virotherapy in the C33A-RFP model and demonstrated an efficient virus-mediated reduction of tumor size and metastatic burden. These results suggest the C33A-RFP cervical cancer model as a new platform to analyze cancer metastases as well as to test novel treatment options to combat metastases.

Hypoxic activation of the PERK/eIF2α arm of the unfolded protein response promotes metastasis through induction of LAMP3

PURPOSE

Conditions of poor oxygenation (hypoxia) are present in many human tumors, including cervix cancer, and are associated with increased risk of metastasis and poor prognosis. Hypoxia is a potent activator of the PERK/eIF2α signaling pathway, a component of the unfolded protein response (UPR) and an important mediator of hypoxia tolerance and tumor growth. Here, the importance of this pathway in the metastasis of human cervix carcinoma was investigated.

EXPERIMENTAL DESIGN

Amplification and expression of LAMP3, a UPR metastasis-associated gene, was examined using FISH and immunofluorescence in a cohort of human cervix tumors from patients who had received oxygen needle electrode tumor oxygenation measurements. To evaluate the importance of this pathway in metastasis in vivo, we constructed a series of inducible cell lines to interfere with PERK signaling during hypoxia and used these in an orthotopic cervix cancer model of hypoxia-driven metastasis.

RESULTS

We show that LAMP3 expression in human cervix tumors is augmented both by gene copy number alterations and by hypoxia. Induced disruption of PERK signaling in established orthotopic xenografts resulted in complete inhibition of hypoxia-induced metastasis to the lymph nodes. This is due, in part, to a direct influence of the UPR pathway on hypoxia tolerance. However, we also find that LAMP3 is a key mediator of hypoxia-driven nodal metastasis, through its ability to promote metastatic properties including cell migration.

CONCLUSION

These data suggest that the association between hypoxia, metastasis, and poor prognosis is due, in part, to hypoxic activation of the UPR and expression of LAMP3. Clin Cancer Res; 19(22); 6126-37. ©2013 AACR.

Hypoxia and metastasis in an orthotopic cervix cancer xenograft model

BACKGROUND

Hypoxia can promote tumor metastasis by mechanisms that are believed to result from changes in gene expression. The current study examined the role of putative metastatic genes regulated by cyclic hypoxia in relation to metastasis formation in orthotopic models of cervix cancer.

METHODS

Orthotopic tumors derived from ME180 human cervix cancer cells or from early generation human cervix cancer xenografts were exposed to cyclic hypoxic conditions during growth in vivo and tumor growth and lymphnode metastases were monitored. Expression of the chemokine receptor CXCR4 and various genes in the Hedgehog (Hh) pathway were inhibited using genetic (inducible shRNA vs CXCR4) small molecule (AMD3100) or antibody (5E1) treatment (CXCR4 and Hh genes, respectively) during tumor growth.

RESULTS

As reported previously, exposure of tumor bearing mice to cyclic hypoxia caused a reduction of tumor growth but a large increase in metastasis. Inhibition of CXCR4 or Hh gene activity during tumor growth further reduced primary tumor size and reduced lymphatic metastasis to levels below those seen in control mice exposed to normoxic conditions.

CONCLUSION

Blocking CXCR4 or Hh gene expression are potential therapeutic pathways for improving cervix cancer treatment.

Low tumor blood flow assessed with perfusion CT correlates with lymphatic involvement in patients with stage T1b non-small cell lung cancer

BACKGROUND

To investigate the correlation of computed tomography (CT) perfusion parameters and lymphatic involvement in patients with stage T1b non-small cell lung cancer (NSCLC).

METHODS

Forty-six patients (30 men and 16 women; age range, 36-73 years; mean age, 57 years), with stage T1b non-small cell lung cancer, underwent perfusion CT before surgery. The correlations between CT perfusion parameters (blood flow, blood volume, peak enhancement intensity), tumor angiogenesis (microvessel density and maturity of microvessels of surgical specimens) and lymphatic involvement were retrospectively investigated. Receiver operator curve (ROC) analysis was used to identify the parameter threshold at which tumors had or did not have lymph node metastasis, and the corresponding sensitivity and specificity were calculated.

RESULTS

A significant tendency for tumors with low blood flow and high density of immature microvessels to show lymphatic involvement was found (all P < 0.001). High correlation (r =-0.769, P < 0.001) was observed between tumor blood flow and immature microvessels. The area under ROC curves (AUC) for blood flow to detect lymph node metastasis was 0.866 (95% confidence interval, 0.766-0.966). For blood flow, the sensitivity, specificity, and accuracy of predicting lymph node metastasis were 88.9, 64.3, and 73.9% respectively, if the cutoff point was set at 43.05 mL/100 g/minute.

CONCLUSIONS

Blood flow may be useful to predict lymphatic involvement before surgery in stage T1b NSCLC.

Dynamic contrast-enhanced magnetic resonance imaging of the metastatic potential of tumors: a preclinical study of cervical carcinoma and melanoma xenografts

BACKGROUND

Gadolinium diethylene-triamine penta-acetic acid (Gd-DTPA)-based dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has been suggested to be a useful non-invasive method for providing biomarkers for personalized cancer treatment. In this preclinical study, we investigated whether Gd-DTPA-based DCE-MRI may have the potential to differentiate between poorly and highly metastatic tumors.

MATERIAL AND METHODS

CK-160 cervical carcinoma and V-27 melanoma xenografts were used as tumor models. Fifty-six tumors were imaged, and parametric images of K(trans) (the volume transfer constant of Gd-DTPA) and v(e) (the fractional distribution volume of Gd-DTPA) were produced by pharmacokinetic analysis of the DCE-MRI series. The host mice were examined for lymph node metastases immediately after the DCE-MRI.

RESULTS

Highly metastatic tumors showed lower values for median K(trans) than poorly metastatic tumors (p = 0.00033, CK-160; p < 0.00001, V-27). Median v(e) was lower for highly than for poorly metastatic V-27 tumors (p = 0.047), but did not differ significantly between metastatic and non-metastatic CK-160 tumors (p > 0.05).

CONCLUSION

This study supports the clinical attempts to establish DCE-MRI as a method for providing biomarkers for tumor aggressiveness and suggests that tumors showing low K(trans) and low ve values may have high probability of lymphogenous metastatic dissemination.

Endothelial cell metabolism and tumour angiogenesis: glucose and glutamine as essential fuels and lactate as the driving force

Angiogenic endothelial cells and tumour cells can survive under hypoxic conditions and even proliferate and migrate in a low-oxygen environment. In both cell types, high rates of glycolysis (i.e. conversion of glucose to lactate) and glutaminolysis provide most of the required biosynthetic intermediates and energy to support sprouting and cell division without coupling to oxidative phosphorylation. This metabolic preference is observed under hypoxic conditions, but also in situations in which oxygen is present. In the case of tumour cells, this is known as the Warburg effect and is largely governed by oncogenes. In endothelial cells lining tumour blood vessels, the option of respiration-independent metabolism allows the neovasculature to resist the hostile environment of fluctuating oxygen tension (ranging from severe hypoxia to quasi-normal levels of oxygen). In addition, accumulation in tumours of lactate, the end-product of glycolysis, largely contributes to the angiogenic phenotype through inhibition of prolyl hydroxylase 2 and the activation of HIF1α and NFκB. Activation of the latter in a hypoxia-independent manner leads to the increased production of interleukin-8/CXCL8 which drives the autocrine stimulation of endothelial cell proliferation and maturation of neovessels. In conclusion, the addiction of proliferating endothelial cells for glucose and glutamine as fuels and the driving force of lactate to promote angiogenesis provide novel potential treatment options without the disadvantages of conventional anti-angiogenic drugs.

A multiple time-scale computational model of a tumor and its micro environment

Experimental evidence suggests that a tumor's environment may be critical to designing successful therapeutic protocols: Modeling interactions between a tumor and its environment could improve our understanding of tumor growth and inform approaches to treatment. This paper describes an efficient, flexible, hybrid cellular automaton-based implementation of numerical solutions to multiple time-scale reaction-diffusion equations, applied to a model of tumor proliferation. The growth and maintenance of cells in our simulation depend on the rate of cellular energy (ATP) metabolized from nearby nutrients such as glucose and oxygen. Nutrient consumption rates are functions of local pH as well as local concentrations of oxygen and other fuels. The diffusion of these nutrients is modeled using a novel variation of random-walk techniques. Furthermore, we detail the effects of three boundary update rules on simulations, describing their effects on computational efficiency and biological realism. Qualitative and quantitative results from simulations provide insight on how tumor growth is affected by various environmental changes such as micro-vessel density or lower pH, both of high interest in current cancer research.

Hypoxia modulates A431 cellular pathways association to tumor radioresistance and enhanced migration revealed by comprehensive proteomic and functional studies

Tumor hypoxia induces cancer cell angiogenesis, invasiveness, treatment resistance, and contributes to poor clinical outcome. However, the molecular mechanism by which tumor hypoxia exerts a coordinated effect on different molecular pathways to enhance tumor growth and survival and lead to poor clinical outcome is not fully understood. In this study, we attempt to elucidate the global protein expression and functional changes in A431 epithelial carcinoma cells induced by hypoxia and reoxygenation using iTRAQ quantitative proteomics and biochemical functional assays. Quantitative proteomics results showed that 4316 proteins were quantified with FDR<1%, in which over 1200 proteins were modulated >1.2 fold, and DNA repair, glycolysis, integrin, glycoprotein turnover, and STAT1 pathways were perturbed by hypoxia and reoxygenation-induced oxidative stress. For the first time, hypoxia was shown to up-regulate the nonhomologous end-joining pathway, which plays a central role in DNA repair of irradiated cells, thereby potentially contributing to the radioresistance of hypoxic A431 cells. The up-regulation of Ku70/Ku80 dimer, a key molecular complex in the nonhomologous end-joining pathway, was confirmed by Western blot and liquid chromatography/tandem mass spectrometry-MRM methods. Functional studies confirmed that up-regulation of glycolysis, integrin, glycoprotein synthesis, and down-regulation of STAT1 pathways during hypoxia enhanced metastastic activity of A431 cells. Migration of A431 cells was dramatically repressed by glycolysis inhibitor (2-Deoxy-d-glucose), glycoprotein synthesis inhibitor (1-Deoxynojirimycin Hydrochloride), and STAT1α overexpression that enhanced the integrin-mediated cell adhesion. These results revealed that hypoxia induced several biological processes involved in tumor migration and radioresistance and provided potential new targets for tumor therapy.

Imaging the impact of Nox4 in cycling hypoxia-mediated U87 glioblastoma invasion and infiltration

PURPOSE

We determined the impact of the cycling hypoxia tumor microenvironment on tumor cell invasion and infiltration in U87 human glioblastoma cells and investigated the underlying mechanisms using molecular bio-techniques and imaging.

PROCEDURES

The invasive phenotype of U87 cells and xenografts exposed to experimentally imposed cycling hypoxic stress in vitro and in vivo was determined by the matrigel invasion assay in vitro and dual optical reporter gene imaging in vivo. RNAi-knockdown technology was utilized to study the role of the NADPH oxidase subunit 4 (Nox4) on cycling hypoxia-mediated tumor invasion.

RESULTS

Cycling hypoxic stress significantly promoted tumor invasion in vitro and in vivo. However, Nox4 knockdown inhibited this effect. Nox4-generated reactive oxygen species (ROS) are required for cycling hypoxia-induced invasive potential in U87 cells through the activation of NF-κB- and ERK-mediated stimulation of MMP-9.

CONCLUSIONS

Cycling hypoxia-induced ROS via Nox4 should be considered for therapeutic targeting of tumor cell invasion and infiltration in glioblastoma.

Impact of transarterial therapy in hepatitis C-related hepatocellular carcinoma on long-term outcomes after liver transplantation

OBJECTIVES

To evaluate the impact of long-term outcomes of transarterial embolization (TAE) therapy in patients with hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC) on the waiting list for liver transplantation (LT).

METHODS

We retrospectively evaluated the post-LT patients with HCV-related HCC who received TAE intervention (n=33) and those who had no treatment (n=47) while on the waiting list to determine long-term outcomes.

RESULTS

Over a 10-year period, of the 424 patients transplanted with HCV, 80 patients had HCC with a tumor burden within Milan criteria. For the entire study cohort, the mean duration of post-LT follow-up was 3.5 years; mean time of transplant waiting list was 120 days; and median post-LT survival was 8.9 years. The survival rates at 1, 3, 5, and 10 years were 82%, 70%, 55%, and 35%, respectively. From the study cohort, 33 patients received TAE and 47 patients did not while on the waiting list. The 2 groups were well matched, except, that the intervention patients received post-LT interferon more often and had a shorter time on the waiting list (56.2 d) when compared with the no treatment group (164.6 d, P<0.001). Median survival in the TAE group was 4.8 years and 8.9 years in the no treatment group. The recurrence rate was 15.6% in the treatment group and 6.9% in the no therapy group (P=0.275).

CONCLUSIONS

Pre-LT transarterial therapy has no benefit on post-LT survival and tumor recurrence in patients with HCV-related HCC who underwent a mean waiting period of <3 months to transplant.

Characterization of the Tumor-Microenvironment in Patient-Derived Cervix Xenografts (OCICx)

Rationale: The tumor microenvironment (TME) is heterogeneous including both malignant and host cell components as well as regions of hypoxia, elevated interstitial fluid pressure (IFP) and poor nutrient supply. The quantitative extent to which the microenvironmental properties of primary tumors are recapitulated in xenograft models is not well characterized. Methods: Xenografts were generated by implanting tumor biopsies directly into the cervix of mice to create a panel of orthotopically-passaged xenografts (OCICx). Tumors were grown to ~1 cm (diameter) and IFP measurements recorded prior to sacrifice. Enlarged para-aortic lymph nodes (>1–2 mm) were excised for histologic confirmation of metastatic disease. Quantitative histological analysis was used to evaluate hypoxia, proliferation, lymphatic and blood vessels in the epithelial and stromal regions of the xenografts and original patient tumour. Results: IFP and nodal disease were not correlated with tumor engraftment. IFP measurements in the xenografts were generally lower than those in the patient’s tumor. Lymphatic metastasis increased with passage number as did levels of hypoxia in the epithelial component of the xenografts. The blood vessel density in the stromal component of the xenografts increased in parallel. When all the markers were compared between the biopsy and the respective 3rd generation xenograft 10 of 11 tumors showed a good correlation. Conclusions: This ongoing study provides characterization about tumoral and stromal heterogeneity in a unique orthotopic xenograft model.

Predicting recurrence after radiotherapy in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. Radiotherapy is a mainstay of treatment, either alone for early stage tumors or combined with chemotherapy for late stage tumors. An overall 5-year survival rate of around 50% for HNSCC demonstrates that treatment is often unsuccessful. Prediction of outcome is, therefore, aimed at sparing patients from ineffective and toxic treatments on the one hand, and indicating more successful treatment modalities on the other. Both functional and genetic assays have been developed to predict intrinsic radiosensitivity, hypoxia, and repopulation rate. Few, however, have shown consistent correlations with outcome across multiple studies. Messenger RNA and microRNA profiling show promise for predicting hypoxia, whereas epidermal growth factor receptor expression combined with other measures of tumor differentiation grade shows promise for predicting repopulation rate. Intrinsic radiosensitivity assays have not proven useful to date, although development of repair protein foci assays indicates promise from preclinical studies. Assays for cancer stem cell content have shown promise in several clinical studies. In addition, 2 assays showing robustness as predictors for outcome in HNSCC are human papilloma virus status and epidermal growth factor receptor expression. Neither these nor stem cell assays, however, can as yet reliably indicate alternative and better treatments for poor prognosis patients. It would be of great value to have assays that predict the benefit for an individual from combining new molecularly targeted agents with radiotherapy to increase response, in particular those that exploit tumor mutations to provide tumor specificity. Predictive assays are being developed for detecting defects in repair pathways for single- and double-strand DNA breaks, which should allow selection of drugs targeting the appropriate backup pathway, thus exploiting the concept of synthetic lethality. This is one of the most promising areas for prediction, both currently and in the future.

Electron paramagnetic resonance imaging of tumor pO₂

Electron paramagnetic resonance imaging (EPRI) can be used to noninvasively and quantitatively obtain three-dimensional maps of tumor pO₂. The paramagnetic tracer triarylmethyl (TAM), a substituted trityl radical moiety, is not toxic to animals and provides narrow isotropic spectra, which is ideal for in vivo EPR imaging experiments. From the oxygen-induced spectral broadening of TAM, pO₂ maps can be derived using EPRI. The instrumentation consists of an EPRI spectrometer and 7T magnetic resonance imaging (MRI) system both operating at a common radiofrequency of 300 MHz. Anatomic images obtained by MRI can be overlaid with pO₂ maps obtained from EPRI. With imaging times of less than 3 min, it was possible to monitor the dynamics of oxygen changes in tumor and distinguish chronically hypoxic regions from acutely hypoxic regions. In this article, the principles of pO₂ imaging with EPR and some relevant examples of tumor imaging are reviewed.

Acute versus chronic hypoxia in tumors: Controversial data concerning time frames and biological consequences

BACKGROUND

Many tumors contain hypoxic regions. Hypoxia, in turn, is known to increase aggressiveness and to be associated with treatment resistance. The two most frequently described and investigated subtypes of tumor hypoxia are acute and chronic. These two subtypes can lead to completely different hypoxia-related responses within the tumor, which could have a direct effect on tumor development and response to treatment. In order to accurately assess the specific biological consequences, it is important to understand which time frames best define acute and chronic hypoxia.

MATERIALS AND METHODS

This article provides an overview of the kinetics of in vitro and in vivo acute and chronic tumor hypoxia. Special attention was paid to differentiate between methods to detect spontaneous in vivo hypoxia and to describe the biological effects of experimental in vitro and in vivo acute and chronic tumor hypoxia.

RESULTS AND CONCLUSIONS

There are large variations in reported spontaneous fluctuations in acute hypoxia that are dependent on the cell lines investigated and the detection method used. In addition to differing hypoxia levels, exposure times used to induce in vitro and in vivo experimental acute and chronic hypoxia range from 30 min to several weeks with no clear boundaries separating the two. Evaluation of the biological consequences of each hypoxia subtype revealed a general trend that acute hypoxia leads to a more aggressive phenotype. Importantly, more information on the occurrence of acute and chronic hypoxia in human tumors is needed to help our understanding of the clinical consequences.

Orthotopic xenograft model of cervical cancer for studying microenvironmental effects on metastasis formation and response to drug treatment

Cancers arising in the uterine cervix are usually squamous cell carcinomas that develop from preneoplastic lesions. They invade locally, and then typically metastasize to the regional lymph nodes and eventually to distant sites. Orthotopically grown xenografts are technically challenging to perform, but recapitulate the clinical situation to a greater extent than xenografts grown at subcutaneous or intramuscular sites. Thus, orthotopic xenografts develop lymphovascular invasion and metastasize to the para-aortic lymphatic chain in a pattern similar to that seen in patients. The extent of (lymph node) metastases is particularly apparent when the implanted tumor cells are transfected to express a fluorescent marker, such as DsRed, which allows the exposed retroperitoneum to be examined by fluorescence microscopy. Described in this unit is a surgical technique for orthotopic implantation and the use of this model for investigating the effects of novel agents as inhibitors of tumor growth and metastasis.