Hypoxia and the presence of human vascular endothelial cells affect prostate cancer cell invasion and metabolism

Stromal Co-Cultivation for Modeling Breast Cancer Dormancy in the Bone Marrow

Cancers metastasize to the bone marrow before primary tumors can be detected. Bone marrow micrometastases are resistant to therapy, and while they are able to remain dormant for decades, they recur steadily and result in incurable metastatic disease. The bone marrow microenvironment maintains the dormancy and chemoresistance of micrometastases through interactions with multiple cell types and through structural and soluble factors. Modeling dormancy in vitro can identify the mechanisms of these interactions. Modeling also identifies mechanisms able to disrupt these interactions or define novel interactions that promote the reawakening of dormant cells. The in vitro modeling of the interactions of cancer cells with various bone marrow elements can generate hypotheses on the mechanisms that control dormancy, treatment resistance and reawakening in vivo. These hypotheses can guide in vivo murine experiments that have high probabilities of succeeding in order to verify in vitro findings while minimizing the use of animals in experiments. This review outlines the existing data on predominant stromal cell types and their use in 2D co-cultures with cancer cells.

Cytotoxic Effects on Breast Cancer Cell Lines of Chalcones Derived from a Natural Precursor and Their Molecular Docking Analysis

This study aimed to determine the in vitro cytotoxicity and understand possible cytotoxic mechanisms via an in silico study of eleven chalcones synthesized from two acetophenones. Five were synthesized from a prenylacetophenone isolated from a plant that grows in the Andean region of the Atacama Desert. The cytotoxic activity of all the synthesized chalcones was tested against breast cancer cell lines using an MTT cell proliferation assay. The results suggest that the prenyl group in the A-ring of the methoxy and hydroxyl substituents of the B-ring appear to be crucial for the cytotoxicity of these compounds. The chalcones 12 and 13 showed significant inhibitory effects against growth in MCF-7 cells (IC₅₀ 4.19 ± 1.04 µM and IC₅₀ 3.30 ± 0.92 µM), ZR-75-1 cells (IC₅₀ 9.40 ± 1.74 µM and IC₅₀ 8.75 ± 2.01µM), and MDA-MB-231 cells (IC₅₀ 6.12 ± 0.84 µM and IC₅₀ 18.10 ± 1.65 µM). Moreover, these chalcones showed differential activity between MCF-10F (IC₅₀ 95.76 ± 1.52 µM and IC₅₀ 95.11 ± 1.97 µM, respectively) and the tumor lines. The in vitro results agree with molecular coupling results, whose affinity energies and binding mode agree with the most active compounds. Thus, compounds 12 and 13 can be considered for further studies and are candidates for developing new antitumor agents. In conclusion, these observations give rise to a new hypothesis for designing chalcones with potential cytotoxicity with high potential for the pharmaceutical industry.

Biologically Targeted Radiation Therapy: Incorporating Patient-Specific Hypoxia Data Derived from Quantitative Magnetic Resonance Imaging

PURPOSE

Hypoxia has been linked to radioresistance. Strategies to safely dose escalate dominant intraprostatic lesions have shown promising results, but further dose escalation to overcome the effects of hypoxia require a novel approach to constrain the dose in normal tissue.to safe levels. In this study, we demonstrate a biologically targeted radiotherapy (BiRT) approach that can utilise multiparametric magnetic resonance imaging (mpMRI) to target hypoxia for favourable treatment outcomes.

METHODS

mpMRI-derived tumour biology maps, developed via a radiogenomics study, were used to generate individualised, hypoxia-targeting prostate IMRT plans using an ultra- hypofractionation schedule. The spatial distribution of mpMRI textural features associated with hypoxia-related genetic profiles was used as a surrogate of tumour hypoxia. The effectiveness of the proposed approach was assessed by quantifying the potential benefit of a general focal boost approach on tumour control probability, and also by comparing the dose to organs at risk (OARs) with hypoxia-guided focal dose escalation (DE) plans generated for five patients.

RESULTS

Applying an appropriately guided focal boost can greatly mitigate the impact of hypoxia. Statistically significant reductions in rectal and bladder dose were observed for hypoxia-targeting, biologically optimised plans compared to isoeffective focal DE plans.

CONCLUSION

Results of this study suggest the use of mpMRI for voxel-level targeting of hypoxia, along with biological optimisation, can provide a mechanism for guiding focal DE that is considerably more efficient than application of a general, dose-based optimisation, focal boost.

Radial Flow Perfusion Enables Real-Time Profiling of Cellular Metabolism at Low Oxygen Levels with Hyperpolarized 13C NMR Spectroscopy

In this study, we describe new methods for studying cancer cell metabolism with hyperpolarized ¹³C magnetic resonance spectroscopy (HP ¹³C MRS) that will enable quantitative studies at low oxygen concentrations. Cultured hepatocellular carcinoma cells were grown on the surfaces of non-porous microcarriers inside an NMR spectrometer. They were perfused radially from a central distributer in a modified NMR tube (bioreactor). The oxygen level of the perfusate was continuously monitored and controlled externally. Hyperpolarized substrates were injected continuously into the perfusate stream with a newly designed system that prevented oxygen and temperature perturbations in the bioreactor. Computational and experimental results demonstrated that cell mass oxygen profiles with radial flow were much more uniform than with conventional axial flow. Further, the metabolism of HP [1-¹³C]pyruvate was markedly different between the two flow configurations, demonstrating the importance of avoiding large oxygen gradients in cell perfusion experiments.

The performance of intravoxel-incoherent motion diffusion-weighted imaging derived hypoxia for the risk stratification of prostate cancer in peripheral zone

PURPOSE

To assess the association between intravoxel-incoherent motion diffusion-weighted imaging (IVIM) derived hypoxia and the aggressiveness of prostate cancer (PCa) and to explore its contribution to the risk stratification of PCa.

METHODS

Seventy-five peripheral zone (PZ) PCa patients, who underwent multiparametric MRI (mpMRI), were included in this study. Systematic ultrasound guided biopsy was used as reference. IVIM was acquired with 5 b values (b = 0∼750 s/mm²). Apparent diffusion coefficient (ADC), pure tissue diffusion (Ds), volume fraction of pseudo-diffusion (fp), hypoxic fraction (HF_DWI), hypoxia score (HS_DWI) and relative oxygen saturation(rOS_DWI), were calculated and histogram analysis was applied. Groups comparison was performed between low-intermediate-grade group (LG, the International Society of Urological Pathology (ISUP) Gleason Grade (GG) ≤2) and high-grade (HG, ISUP GG ≥ 3) group. The correlation between diffusion parameters and ISUP GG was assessed. Cross-validated Support Vector Machine (SVM) Classification was performed and compared with univariate ROC analysis to explore the risk stratification of PZ PCa.

RESULTS

Mean, median, and the 10th percentile of Ds differed significantly between groups (p < 0.05). Several parameters significantly correlated with ISUP grade, and the 10th percentile of Ds showed the strongest correlation (ρ= - 0.284). The prediction model containing IVIM derived hypoxia yielded an area under the receiver operating characteristics curve (AUC) ranging 0.749-0.786 for cross-validation. The AUCs of the SVM modeling were higher than that of any single parameter.

CONCLUSION

IVIM derived hypoxia demonstrated significant correlation with the aggressiveness of PCa. It's supplemental to the MRI assessment of PCa with a promising stratification of risk stratification of PZ PCa.

MRI and MRS of intact perfused cancer cell metabolism, invasion, and stromal cell interactions

Because of the spatial and temporal heterogeneities of cancers, technologies to investigate cancer cells and the consequences of their interactions with abnormal physiological environments, such as hypoxia and acidic extracellular pH, with stromal cells, and with the extracellular matrix, under controlled conditions, are valuable to gain insights into the functioning of cancers. These insights can lead to an understanding of why cancers invade and metastasize, and identify effective treatment strategies. Here we have provided an overview of the applications of MRI/MRS/MRSI to investigate intact perfused cancer cells, their metabolism and invasion, and their interactions with stromal cells and the extracellular matrix.

Characterization of the Tumor Microenvironment and Tumor-Stroma Interaction by Non-invasive Preclinical Imaging

Tumors are often characterized by hypoxia, vascular abnormalities, low extracellular pH, increased interstitial fluid pressure, altered choline-phospholipid metabolism, and aerobic glycolysis (Warburg effect). The impact of these tumor characteristics has been investigated extensively in the context of tumor development, progression, and treatment response, resulting in a number of non-invasive imaging biomarkers. More recent evidence suggests that cancer cells undergo metabolic reprograming, beyond aerobic glycolysis, in the course of tumor development and progression. The resulting altered metabolic content in tumors has the ability to affect cell signaling and block cellular differentiation. Additional emerging evidence reveals that the interaction between tumor and stroma cells can alter tumor metabolism (leading to metabolic reprograming) as well as tumor growth and vascular features. This review will summarize previous and current preclinical, non-invasive, multimodal imaging efforts to characterize the tumor microenvironment, including its stromal components and understand tumor-stroma interaction in cancer development, progression, and treatment response.

Lymphatic endothelial cells actively regulate prostate cancer cell invasion

Lymphatic vessels serve as the primary route for metastatic spread to lymph nodes. However, it is not clear how interactions between cancer cells and lymphatic endothelial cells (LECs), especially within hypoxic microenvironments, affect the invasion of cancer cells. Here, using an MR compatible cell perfusion assay, we investigated the role of LEC-prostate cancer (PCa) cell interaction in the invasion and degradation of the extracellular matrix (ECM) by two human PCa cell lines, PC-3 and DU-145, under normoxia and hypoxia, and determined the metabolic changes that occurred under these conditions. We observed a significant increase in the invasion of ECM by invasive PC-3 cells, but not poorly invasive DU-145 cells when human dermal lymphatic microvascular endothelial cells (HMVEC-dlys) were present. Enhanced degradation of ECM by PC-3 cells in the presence of HMVEC-dlys identified interactions between HMVEC-dlys and PCa cells influencing cancer cell invasion. The enhanced ECM degradation was partly attributed to increased MMP-9 enzymatic activity in PC-3 cells when HMVEC-dlys were in close proximity. Significantly higher uPAR and MMP-9 expression levels observed in PC-3 cells compared to DU-145 cells may be one mechanism for increased invasion and degradation of matrigel by these cells irrespective of the presence of HMVEC-dlys. Hypoxia significantly decreased invasion by PC-3 cells, but this decrease was significantly attenuated when HMVEC-dlys were present. Significantly higher phosphocholine was observed in invasive PC-3 cells, while higher glycerophosphocholine was observed in DU-145 cells. These metabolites were not altered in the presence of HMVEC-dlys. Significantly increased lipid levels and lipid droplets were observed in PC-3 and DU-145 cells under hypoxia reflecting an adaptive survival response to oxidative stress. These results suggest that in vivo, invasive cells in or near lymphatic endothelial cells are likely to be more invasive and degrade the ECM to influence the metastatic cascade. Copyright © 2016 John Wiley & Sons, Ltd.

Enzymatically Regulated Peptide Pairing and Catalysis for the Bioanalysis of Extracellular Prometastatic Activities of Functionally Linked Enzymes

Diseases such as cancer arise from systematical reconfiguration of interactions of exceedingly large numbers of proteins in cell signaling. The study of such complicated molecular mechanisms requires multiplexed detection of the inter-connected activities of several proteins in a disease-associated context. However, the existing methods are generally not well-equipped for this kind of application. Here a method for analyzing functionally linked protein activities is developed based on enzyme controlled pairing between complementary peptide helix strands, which simultaneously enables elaborate regulation of catalytic activity of the paired peptides. This method has been used to detect three different types of protein modification enzymes that participate in the modification of extracellular matrix and the formation of invasion front in tumour. In detecting breast cancer tissue samples using this method, up-regulated activity can be observed for two of the assessed enzymes, while the third enzyme is found to have a subtle fluctuation of activity. These results may point to the application of this method in evaluating prometastatic activities of proteins in tumour.

A lipidomics investigation of the induced hypoxia stress on HeLa cells by using MS and NMR techniques

Induced hypoxia stress on cervical cancer derived cells (HeLa cells) leads to significant changes in their membrane lipid profiles. The lipidome of HeLa cells was characterized by a joint approach wherein liquid chromatography-mass spectrometry (LC-MS) analysis was followed by high resolution NMR measurements. Multivariate data analysis showed apparent separation between control and hypoxia-treated HeLa cells and thus demonstrated hypoxia effects on lipid metabolism. The most striking finding was that hypoxia stimulation significantly reduced the total amount of cellular phosphoinositols (PI) but caused a prominent increase in the amount of lyso phosphocholines (lyso-PC) and lyso phosphoethanolamines (lyso-PE). The observed decrease of PI amount under hypoxic conditions is probably due to the accumulation of cellular myo-inositol, which is known to play a critical role in de novo synthesis of PI. Moreover, our study suggests that polyunsaturated phospholipid species are stronger biomarkers for discriminating the effect of hypoxia treatment. The evaluation of changes in the average unsaturation index (UI) of the membrane lipids acyl chains reveals that UI slightly increases in several lipid classes, thus affecting membrane fluidity and further membrane-dependent functions. The plausible mechanisms by which HeLa cells adapt to hypoxia conditions are also briefly reported.

MRI of metastasis-permissive microenvironments

One of the earliest documented observations of the importance of the microenvironment in metastasis was made by Stephen Paget in 1889. More than a century later, the metastatic cascade remains a major cause of mortality from cancer. Cancer meets the criterion of a successful organization that is able to survive by adapting to changing environments. In fact, the tumor microenvironment and stroma are co-opted and shaped by cancer cells to derive a survival advantage. Cohesive strategies integrating advances in molecular biology and chemistry, with noninvasive multimodality imaging, provide new insights into the role of the tumor microenvironment in promoting metastasis from primary tumors as well as insights into environments that attract and permit cancer cells to establish colonies in distant organs. This article provides an overview of molecular and functional imaging characterization of microenvironments that can promote or permit cancer cells to metastasize and the microenvironmental characteristics of distant metastases.

Micrometer-scale oxygen delivery rearranges cells and prevents necrosis in tumor tissue in vitro

Oxygen availability plays a critical role in cancer progression and is correlated with poor prognosis. Despite this connection, the independent effects of oxygen gradients on tumor tissues have not been measured. To address this, we developed an oxygen delivery device that uses microelectrodes to generate oxygen directly underneath three-dimensional tumor cylindroids composed of colon carcinoma cells. The extent of cell death was measured using fluorescence staining. Supplying oxygen for 60 h eliminated the necrotic region typically found in the center of cylindroids despite the continued presence of other nutrient gradients. A mathematical model of cylindroid growth showed that the rate of cell death was more sensitive to oxygen than the growth rate. After oxygenation, a ring of dead cells was observed at the outside edge of cylindroids, and dead cells were observed moving outward from cylindroid centers. This movement suggests that dead cells were pushed by viable cells migrating in response to oxygen gradients, a mechanism that may connect transient oxygen gradients to metastasis formation. These measurements show that oxygen gradients are a primary factor governing cell viability and rearrange cells in tumors.

Expression of the non-gastric H+/K+ ATPase ATP12A in normal and pathological human prostate tissue

Altered cellular proton handling and cell volume regulation are hallmarks of tumorigenesis. To investigate a possible involvement of the non-gastric H(+)/K(+) ATPase ATP12A (ATP1AL1) in prostate cancer, we performed immunohistochemistry in formalin-fixed, paraffin-embedded histological sections from benign and malignant human prostate lesions. Normal prostate tissue displayed a membrane-bound ATP12A staining with focal accumulated pattern, whereas in the benign prostate hyperplasia (BPH) and cancerous prostate tissue (tumor grade I-III) the protein appears to be displaced in the luminal cells of the glandular epithelium. Hence, the expression pattern of ATP12A is markedly altered in BPH and prostate cancer. To test for altered gene expression of ATP12A we performed quantitative reverse transcriptase PCR (QRT-PCR) in normal (tumor-free) prostate tissue, BPH and tumor stages I-III using a prostate cancer cDNA array. However, no significantly different expression levels could be detected in the various disease states compared to normal tissue, which contrasts the findings from immunohistochemistry and points to the possibility of altered post-translational processing and/or sorting of the protein. We further show that ATP12A mRNA is expressed at different levels in PC-3 and LNCaP prostate cancer cells, with a significant ~26-fold higher expression in the latter cell type. Protein expression in these tumor cell lines was verified by Western blot.

Impact of hypoxia on the metastatic potential of human prostate cancer cells

PURPOSE

Intratumoral hypoxia is known to be associated with radioresistance and metastasis. The present study examined the effect of acute and chronic hypoxia on the metastatic potential of prostate cancer PC-3, DU145, and LNCaP cells.

METHODS AND MATERIALS

Cell proliferation and clonogenicity were tested by MTT assay and colony formation assay, respectively. "Wound-healing" and Matrigel-based chamber assays were used to monitor cell motility and invasion. Hypoxia-inducible factor 1 alpha (HIF-1α) expression was tested by Western blot, and HIF-1-target gene expression was detected by real-time polymerase chain reaction. Secretion of matrix metalloproteinases (MMPs) was determined by gelatin zymography.

RESULTS

When PC-3 cells were exposed to 1% oxygen (hypoxia) for various periods of time, chronic hypoxia (≥24 h) decreased cell proliferation and induced cell death. In contrast, prostate cancer cells exposed to acute hypoxia (≤6 h) displayed increased motility, clonogenic survival, and invasive capacity. At the molecular level, both hypoxia and anoxia transiently stabilized HIF-1α. Exposure to hypoxia also induced the early expression of MMP-2, an invasiveness-related gene. Treatment with the HIF-1 inhibitor YC-1 attenuated the acute hypoxia-induced migration, invasion, and MMP-2 activity.

CONCLUSIONS

The length of oxygen deprivation strongly affected the functional behavior of all three prostate cancer cell lines. Acute hypoxia in particular was found to promote a more aggressive metastatic phenotype.

A decade in prostate cancer: from NMR to metabolomics

Over the past 30 years, continuous progress in the application of nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance spectroscopic imaging (MRSI) to the detection, diagnosis and characterization of human prostate cancer has turned what began as scientific curiosity into a useful clinical option. In vivo MRSI technology has been integrated into the daily care of prostate cancer patients, and innovations in ex vivo methods have helped to establish NMR-based prostate cancer metabolomics. Metabolomic and multimodality imaging could be the future of the prostate cancer clinic--particularly given the rationale that more accurate interrogation of a disease as complex as human prostate cancer is most likely to be achieved through paradigms involving multiple, instead of single and isolated, parameters. The research and clinical results achieved through in vivo MRSI and ex vivo NMR investigations during the first 11 years of the 21st century illustrate areas where these technologies can be best translated into clinical practice.

Hypoxia triggers major metabolic changes in AML cells without altering indomethacin-induced TCA cycle deregulation

Our previous studies have shown that the nonsteroidal anti-inflammatory drug indomethacin exhibits antileukemic activity in vitro and can inhibit the aldo-keto reductase AKR1C3, which we identified as a novel target in acute myeloid leukemia. However, the antileukemic actions of indomethacin are likely to be complex and extend beyond inhibition of either AKR1C3 or cycloxygenases. To further understand the antileukemic activity of indomethacin we have used untargeted nuclear magnetic resonance-based metabolic analysis to characterize the responses of KG1a and K562 cell lines in both normal culture conditions and in hypoxia, which better represents the tumor environment in vivo. Hypoxia induced dramatic metabolic changes in untreated KG1a and K562, including adaptation of both phospholipid and glycolytic metabolism. Despite these changes, both cell lines sustained relatively unaltered mitochondrial respiration. The administration of indomethacin induced similar metabolic responses regardless of the oxygen level in the environment. Notable exceptions included metabolites associated with de novo fatty acid synthesis and choline phospholipid metabolism. Collectively, these results suggest that leukemia cells have the inherent ability to tolerate changes in oxygen tension while maintaining an unaltered mitochondrial respiration. However, the administration of indomethacin significantly increased oxidative stress in both KG1a and K562, inducing mitochondrial dysfunction, regardless of the oxygenation conditions. These findings emphasize the particular pertinence of the tricarboxylic acid cycle to the survival of cancer cells and may explain why some antileukemic drugs have been discovered and developed successfully despite the use of culture conditions that do not reflect the hypoxic environment of cancer cells in vivo.

Hypoxic tumor microenvironments reduce collagen I fiber density

Although the mechanisms through which hypoxia influences several phenotypic characteristics such as angiogenesis, selection for resistance to apoptosis, resistance to radiation and chemotherapy, and increased invasion and metastasis are well characterized, the relationship between tumor hypoxia and components of the extracellular matrix (ECM) is relatively unexplored. The collagen I (Col1) fiber matrix of solid tumors is the major structural part of the ECM. Col1 fiber density can increase tumor initiation, progression, and metastasis, with cancer cell invasion occurring along radially aligned Col1 fibers. Here we have investigated the influence of hypoxia on Col1 fiber density in solid breast and prostate tumor models. Second harmonic generation (SHG) microscopy was used to detect differences in Col1 fiber density and volume between hypoxic and normoxic tumor regions. Hypoxic regions were detected by fluorescence microscopy, using tumors derived from human breast and prostate cancer cell lines stably expressing enhanced green fluorescent protein (EGFP) under transcriptional control of the hypoxia response element. In-house fiber analysis software was used to quantitatively analyze Col1 fiber density and volume from the SHG microscopy images. Normoxic tumor regions exhibited a dense mesh of Col1 fibers. In contrast, fewer and structurally altered Col1 fibers were detected in hypoxic EGFP-expressing tumor regions. Microarray gene expression analyses identified increased expression of lysyl oxidase and reduced expression of some matrix metalloproteases in hypoxic compared with normoxic cancer cells. These results suggest that hypoxia mediates Col1 fiber restructuring in tumors, which may impact delivery of macromolecular agents as well as dissemination of cells.

Multimodal mass spectrometric imaging of small molecules reveals distinct spatio-molecular signatures in differentially metastatic breast tumor models

Phosphocholine (PC) and total choline (tCho) are increased in malignant breast tumors. In this study, we combined magnetic resonance spectroscopic imaging (MRSI), mass spectrometry (MS) imaging, and pathologic assessment of corresponding tumor sections to investigate the localization of choline metabolites and cations in viable versus necrotic tumor regions in the nonmetastatic MCF-7 and the highly metastatic MDA-MB-231 breast cancer xenograft models. In vivo three-dimensional MRSI showed that high tCho levels, consisting of free choline (Cho), PC, and glycerophosphocholine (GPC), displayed a heterogeneous spatial distribution in the tumor. MS imaging performed on tumor sections detected the spatial distributions of individual PC, Cho, and GPC, as well as sodium (Na+) and potassium (K+), among many others. PC and Cho intensity were increased in viable compared with necrotic regions of MDA-MB-231 tumors, but relatively homogeneously distributed in MCF-7 tumors. Such behavior may be related to the role of PC and PC-related enzymes, such as choline kinase, choline transporters, and others, in malignant tumor growth. Na+ and K+ colocalized in the necrotic tumor areas of MDA-MB-231 tumors, whereas in MCF-7 tumors, Na+ was detected in necrotic and K+ in viable tumor regions. This may be attributed to differential Na+/K+ pump functions and K+ channel expressions. Principal component analysis of the MS imaging data clearly identified different tumor microenvironmental regions by their distinct molecular signatures. This molecular information allowed us to differentiate between distinct tumor regions and tumor types, which may, in the future, prove clinically useful in the pathologic assessment of breast cancers.

Choline kinase overexpression increases invasiveness and drug resistance of human breast cancer cells

A direct correlation exists between increased choline kinase (Chk) expression, and the resulting increase of phosphocholine levels, and histological tumor grade. To better understand the function of Chk and choline phospholipid metabolism in breast cancer we have stably overexpressed one of the two isoforms of Chk-alpha known to be upregulated in malignant cells, in non-invasive MCF-7 human breast cancer cells. Dynamic tracking of cell invasion and cell metabolism were studied with a magnetic resonance (MR) compatible cell perfusion assay. The MR based invasion assay demonstrated that MCF-7 cells overexpressing Chk-alpha (MCF-7-Chk) exhibited an increase of invasion relative to control MCF-7 cells (0.84 vs 0.3). Proton MR spectroscopy studies showed significantly higher phosphocholine and elevated triglyceride signals in Chk overexpressing clones compared to control cells. A test of drug resistance in MCF-7-Chk cells revealed that these cells had an increased resistance to 5-fluorouracil and higher expression of thymidylate synthase compared to control MCF-7 cells. To further characterize increased drug resistance in these cells, we performed rhodamine-123 efflux studies to evaluate drug efflux pumps. MCF-7-Chk cells effluxed twice as much rhodamine-123 compared to MCF-7 cells. Chk-alpha overexpression resulted in MCF-7 human breast cancer cells acquiring an increasingly aggressive phenotype, supporting the role of Chk-alpha in mediating invasion and drug resistance, and the use of phosphocholine as a biomarker of aggressive breast cancers.

Hypoxia modulates EWS-FLI1 transcriptional signature and enhances the malignant properties of Ewing's sarcoma cells in vitro

Hypoxia is an important condition in the tumor cell microenvironment and approximately 1% to 1.5% of the genome is transcriptionally responsive to hypoxia with hypoxia-inducible factor-1 (HIF-1) as a major mediator of transcriptional activation. Tumor hypoxia is associated with a more aggressive phenotype of many cancers in adults, but data on pediatric tumors are scarce. Because, by immunohistochemistry, HIF-1alpha expression was readily detectable in 18 of 28 primary Ewing's sarcoma family tumors (ESFT), a group of highly malignant bone-associated tumors in children and young adults, we studied the effect of hypoxia on ESFT cell lines in vitro. Intriguingly, we found that EWS-FLI1 protein expression, which characterizes ESFT, is upregulated by hypoxia in a HIF-1alpha-dependent manner. Hypoxia modulated the EWS-FLI1 transcriptional signature relative to normoxic conditions. Both synergistic as well as antagonistic transcriptional effects of EWS-FLI1 and of hypoxia were observed. Consistent with alterations in the expression of metastasis-related genes, hypoxia stimulated the invasiveness and soft agar colony formation of ESFT cells in vitro. Our data represent the first transcriptome analysis of hypoxic ESFT cells and identify hypoxia as an important microenvironmental factor modulating EWS-FLI1 expression and target gene activity with far-reaching consequences for the malignant properties of ESFT.

The War on Cancer rages on

In 1971, the "War on Cancer" was launched by the US government to cure cancer by the 200-year anniversary of the founding of the United States of America, 1976. This article briefly looks back at the progress that has been made in cancer research and compares progress made in other areas of human affliction. While progress has indeed been made, the battle continues to rage on.

A concise review of mass spectrometry imaging

Mass spectrometric imaging allows the investigation of the spatial distribution of molecules at complex surfaces. The combination of molecular speciation with local analysis renders a chemical microscope that can be used for the direct biomolecular characterization of histological tissue surfaces. MS based imaging advantageously allows label-free detection and mapping of a wide-range of biological compounds whose presence or absence can be the direct result of disease pathology. Successful detection of the analytes of interest at the desired spatial resolution requires careful attention to several steps in the mass spectrometry imaging protocol. This review will describe and discuss a selected number of crucial developments in ionization, instrumentation, and application of this innovative technology. The focus of this review is on the latest developments in imaging MS. Selected biological applications are employed to illustrate some of the novel features discussed. Two commonly used MS imaging techniques, secondary ion mass spectrometric (SIMS) imaging and matrix-assisted laser desorption ionization (MALDI) mass spectrometric imaging, center this review. New instrumental developments are discussed that extend spatial resolution, mass resolving power, mass accuracy, tandem-MS capabilities, and offer new gas-phase separation capabilities for both imaging techniques. It will be shown how the success of MS imaging is crucially dependent on sample preparation protocols as they dictate the nature and mass range of detected biomolecules that can be imaged. Finally, developments in data analysis strategies for large imaging datasets will be briefly discussed.

DNA methyltransferase inhibition induces mouse embryonic stem cell differentiation into endothelial cells

Understanding endothelial cell (EC) differentiation is a step forward in tissue engineering, controlling angiogenesis, and endothelial dysfunction. We hypothesized that epigenetic activation of EC lineage specification genes is an important mediator of embryonic stem cell (ESC) differentiation into EC. Mouse ESC was differentiated by removing leukemia inhibitory factor (LIF) from the maintenance media in the presence or absence of the specific DNA methyltransferase (DNMT) inhibitor 5'-aza-2'-deoxycytidine (aza-dC). Expression of EC specification and marker genes was monitored by quantitative PCR, western, immunocytochemistry, and flow cytometry. Functionality of differentiated EC was assessed by angiogenesis assay. The methylation status in the proximal promoter CpGs of the mediators of EC differentiation VEGF-A, BMP4, and EPAS-1 as well as of the mature EC marker VE-cadherin was determined by bisulfite sequencing. ESC differentiation resulted in repression of OCT4 expression in both the absence and presence of aza-dC treatment. However, significant increase in angiogenesis and expression of the mediators of EC differentiation and EC-specific genes was only observed in aza-dC-treated cells. The DNMT inhibition-mediated increase in EC specification and marker gene expression was not associated with demethylation of these genes. These studies suggest that DNMT inhibition is an efficient inducer of EC differentiation from ESC.

Neoplasia: the second decade

This issue marks the end of the 10-year anniversary of Neoplasia where we have seen exciting growth in both number of submitted and published articles in Neoplasia. Neoplasia was first published in 1999. During the past 10 years, Neoplasia has dynamically adapted to the needs of the cancer research community as technologies have advanced. Neoplasia is currently providing access to articles through PubMed Central to continue to facilitate rapid broad-based dissemination of published findings to the scientific community through an Open Access model. This has in part helped Neoplasia to achieve an improved impact factor this past year, demonstrating that the manuscripts published by Neoplasia are of great interest to the overall cancer research community. This past year, Neoplasia received a record number of articles for review and has had a 21% increase in the number of published articles.

PSA response signatures - a powerful new prognostic indicator after radiation for prostate cancer?

BACKGROUND

We sought to determine whether inter-patient variations in pattern of PSA changes after radiation exist and, if so, are they prognostically significant.

METHODS

In the Trans-Tasman Radiation Oncology Group (TROG) 96.01 randomized controlled trial, patients with T2b,c,3,4 N0 prostate cancer (PC) were randomised to 0, 3 or 6months maximal androgen deprivation prior to 66Gy to the prostate and seminal vesicles (XRT). Patterns of anatomical site of failure were one of the trial endpoints. Serial serum PSA's were mandated at all follow-up visits. Pattern recognition software was developed to characterize PSA response "signatures" (PRS) after therapy in individual patients.

RESULTS

By 2000, 270 eligible patients were randomised to radiation alone. Individual patient PSA values were observed to descend after radiation according to one of two characteristic "signatures": single exponential (PRS Type 1), non-exponential (PRS Type 2). Compared to PRS Type 1, men with PRS Type 2 (50% of the group) had lower PSA nadir (nPSA) levels (p<.0001), longer doubling times on relapse (p=.006) and significantly lower rates of local (hazard ratio [HR]: 0.47, 95% confidence interval [0.30-0.75], p=.0014) and distant failure (HR: 0.25[0.13-0.46], p<.0001), death due to PC (HR: 0.20[0.10-0.42], p<.0001) and death due to any cause (HR: 0.37 [0.23-0.60], p<.0001). PRS retained its powerful prognostic significance in Cox models that incorporated all key pre-treatment covariates and nPSA.

CONCLUSIONS

PRS reflect the presence of tumor phenotypes that vary substantially in their clinical behavior and response to XRT. Molecular characterization is now necessary.

Hypoxia-specific drug tirapazamine does not abrogate hypoxic tumor cells in combination therapy with irinotecan and methylselenocysteine in well-differentiated human head and neck squamous cell carcinoma a253 xenografts

Well-differentiated hypoxic regions in head and neck squamous cell carcinoma like in A253 xenografts are avascular and, therefore, hinder drug delivery leading to drug resistance and tumor regrowth. Methylselenocysteine (MSC, 0.2 mg/mouse per day per oral for 35 days starting 7 days before the first irinotecan (CPT-11)) has been found to increase efficacy of a wide variety of chemotherapeutic agents including CPT-11 (100 mg/kg per week x 4 intravenously). Whereas CPT-11 leads to a 10% complete response (CR) in A253 xenografts, the combination of MSC and CPT-11 increased the CR to 70%. Surviving tumors were found to consist largely of avascular hypoxic regions. Here, we investigated the combination of tirapazamine (TPZ, 70 mg/kg per week intraperitoneal x 4 administered 3 or 72 hours before CPT-11), a bioreductive drug in clinical trial with selective toxicity for hypoxic cells, with MSC and CPT-11 in further enhancing the cure rates. Tumor response, change in tumor hypoxic regions, and DNA damage were monitored in vivo. Tirapazamine administered 3 hours before CPT-11 in combination with MSC + CPT-11 led to a lower tumor burden. Tirapazamine did not increase cure rate beyond that of MSC + CPT-11 combination and was instead found to decrease cures with no evidence of an increased DNA damage or a significant reduction in avascular hypoxic tumor regions. CD31 immunostaining in A253 demonstrated disruption of tumor vessels by TPZ that could lower cytotoxic drug delivery to carbonic anhydrase IX-positive hypoxic tumor cells and may explain at least partially these unexpected results.