Survival Pathways of HIF-Deficient Tumour Cells: TCA Inhibition, Peroxisomal Fatty Acid Oxidation Activation and an AMPK-PGC-1α Hypoxia Sensor

The HIF-1 and HIF-2 (HIF1/2) hypoxia responses are frequently upregulated in cancers, and HIF1/2 inhibitors are being developed as anticancer drugs. How could cancers resist anti-HIF1/2 therapy? We studied metabolic and molecular adaptations of HIF-1β-deficient Hepa-1c4, a hepatoma model lacking HIF1/2 signalling, which mimics a cancer treated by a totally effective anti-HIF1/2 agent. [1,2-13C2]-D-glucose metabolism was measured by SiDMAP metabolic profiling, gene expression by TaqMan, and metabolite concentrations by 1H MRS. HIF-1β-deficient Hepa-1c4 responded to hypoxia by increasing glucose uptake and lactate production. They showed higher glutamate, pyruvate dehydrogenase, citrate shuttle, and malonyl-CoA fluxes than normal Hepa-1 cells, whereas pyruvate carboxylase, TCA, and anaplerotic fluxes decreased. Hypoxic HIF-1β-deficient Hepa-1c4 cells increased expression of PGC-1α, phospho-p38 MAPK, and PPARα, suggesting AMPK pathway activation to survive hypoxia. They had higher intracellular acetate, and secreted more H2O2, suggesting increased peroxisomal fatty acid β-oxidation. Simultaneously increased fatty acid synthesis and degradation would have "wasted" ATP in Hepa-1c4 cells, thus raising the [AMP]:[ATP] ratio, and further contributing to the upregulation of the AMPK pathway. Since these tumour cells can proliferate without the HIF-1/2 pathways, combinations of HIF1/2 inhibitors with PGC-1α or AMPK inhibitors should be explored.

Problematic Internet Use Among University Students in Jamaica

The prevalence of problematic Internet use (PIU) and its associated negative outcomes among college students has been heavily researched in developed countries. However, despite the increased accessibility of the Internet and indicators which may suggest PIU in developing countries such as Jamaica, PIU in this context remains grossly understudied. This study surveyed 277 Jamaican university students and found evidence of PIU, with younger respondents (ages 18-23) at risk. The findings also indicate that the predictors of PIU in this sample are depressive symptomatology, avoidant-attachment, and low social connectedness (R 2 = .208, F[7, 269] = 10.112, p < .001). Findings from the current study highlight that problematic Internet use is of concern in this developing context and warrants further exploration.

697 The Use of Augmented and Mixed Reality Technology to Improve Surgical Outcomes: A Systematic Review

Aim

The use of augmented and mixed reality technology is a novel and rapidly developing field. This technology has generated significant interest in surgery, however the evidence supporting its proposed benefits is limited. This systematic review aims to critically appraise the intraoperative use of augmented and mixed reality technology to improve surgical outcomes in order to provide directions for future research.

Method

This systematic review is registered with PROSPERO (CRD42020205892) and was performed in adherence to PRISMA guidelines. Studies reporting primary data on surgical outcomes of the intraoperative use of augmented and mixed reality technology were included. A structured search of major literature databases was performed. Risk of bias was assessed following the guidance of the Cochrane Handbook.

Results

68 studies met the inclusion criteria, with 63 reporting the intraoperative use of augmented reality technology and 5 reporting the use of mixed reality. The number and methodological quality of these studies is increasing. The intraoperative use of this technology has been demonstrated to reduce operative times, intraoperative blood loss and lengths of hospital admissions in specific settings. The widespread adoption of this technology faces the challenges of its cost, technical precision and integration into the surgical workflow.

Conclusions

The intraoperative use of augmented and mixed reality technology is an area of research still in its early stages, with an increasing number of methodologically robust studies on the subject. Current results suggest that the use of this technology is safe and, in certain applications, has the potential to significantly improve surgical and health-economic outcomes.

Hypoxia

Oxygen (O2) is the most commonly used drug in medicine and in anaesthesia. It is vital for all aerobic respiration in humans where it acts as the terminal electron acceptor during oxidative phosphorylation, resulting in the synthesis of adenosine triphosphate (ATP). This in turn supplies energy to all the body’s metabolic processes.

Abstract P2-09-24: Combination treatment with bromodomain and extra-terminal motif inhibitors in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is one of the most aggressive subtypes of breast cancer. TNBC affects younger women and is characterized by earlier rates of relapse, higher frequency of visceral metastases, and shorter survival outcomes when compared to ER+ or HER2+ disease. Although the disease only represents ˜15% of all breast cancer cases, it accounts for 25% of all breast cancer deaths – with treatment options currently limited to chemotherapy. Development of targeted therapies for TNBC is challenging due to molecular heterogeneity and lack of high-frequency “driver” alterations amenable to therapeutic intervention. Recent studies have demonstrated increased sensitivity of TNBC to the anti-proliferative effects of Bromodomain and Extra-Terminal motif inhibitor (BETi) compared to the other breast cancer subtypes. To determine mechanisms of sensitivity to BETi, we analyzed the effect of a BETi across a panel of TNBC cell line models and identified cell lines that were both sensitive and insensitive to BETi. With the intent of identifying biomarkers of sensitivity, we performed RNA-seq and precision nuclear run-on and sequencing (PRO-seq) on both sensitive and insensitive cell line models and data generated identified significant differences in key growth regulatory and apoptotic signaling pathways, including notable differences in Myc-dependent signaling. Our data suggest potential biomarkers of BETi-sensitivity that may be of value in further pre-clinical studies. Further, our results provide mechanistic rationale for combinations of BETi with select, targeted therapies in a disease that is in need of new therapeutic intervention.

Citation Format: Schafer JM, Lehmann BD, Redman LN, Liu P, Stubbs M, Ruggeri B, Scherle P, Pietenpol JA. Combination treatment with bromodomain and extra-terminal motif inhibitors in triple-negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-09-24.

The action of β-hydroxybutyrate on the growth, metabolism and global histone H3 acetylation of spontaneous mouse mammary tumours: evidence of a β-hydroxybutyrate paradox

BACKGROUND

Ketone bodies have both metabolic and epigenetic roles in cancer. In several studies, they showed an anti-cancer effect via inhibition of histone deacetylases; however, other studies observed faster tumour growth. The related molecule butyrate also inhibits growth of some cancer cells and accelerates it in others. This "butyrate paradox" is thought to be due to butyrate mediating histone acetylation and thus inhibiting cell proliferation in cancers that preferentially utilise glucose (the Warburg effect); whereas in cells that oxidise butyrate as a fuel, it fails to reach inhibitory concentrations and can stimulate growth.

METHODS

We treated transgenic mice bearing spontaneous MMTV-NEU-NT mammary tumours with the ketone body β-hydroxybutyrate (β-OHB) and monitored tumour growth, metabolite concentrations and histone acetylation. In a cell line derived from these tumours, we also measured uptake of β-OHB and glucose, and lactate production, in the absence and presence of β-OHB.

RESULTS

β-OHB administration accelerated growth of MMTV-NEU-NT tumours, and their metabolic profile showed significant increases in ATP, glutamine, serine and choline-related metabolites. The β-OHB concentration within the treated tumours, 0.46 ± 0.05 μmol/g, had no effect on histone acetylation as shown by western blots. Cultured tumour cells incubated with 0.5 mM β-OHB showed β-OHB uptake that would be equivalent to 54% of glycolytic ATP phosphorylation and no significant change in glucose consumption or lactate production.

CONCLUSIONS

These results suggest that a β-OHB paradox may occur in these mammary tumours in a manner analogous to the butyrate paradox. At low β-OHB concentrations (<1 mM, as observed in our tumour model post-treatment), and in the absence of a Warburg effect, β-OHB is consumed and thus acts as an oxidative energy source and not as an epigenetic factor. This would explain the increase in tumour growth after treatment, the metabolic profiles and the absence of an effect on histone H3 acetylation.

Metabolomic changes during cellular transformation monitored by metabolite-metabolite correlation analysis and correlated with gene expression

To investigate metabolic changes during cellular transformation, we used a 1H NMR based metabolite-metabolite correlation analysis (MMCA) method, which permits analysis of homeostatic mechanisms in cells at the steady state, in an inducible cell transformation model. Transcriptomic data were used to further explain the results. Transformed cells showed many more metabolite-metabolite correlations than control cells. Some had intuitively plausible explanations: a shift from glycolysis to amino acid oxidation after transformation was accompanied by a strongly positive correlation between glucose and glutamine and a strongly negative one between lactate and glutamate; there were also many correlations between the branched chain amino acids and the aromatic amino acids. Others remain puzzling: after transformation strong positive correlations developed between choline and a group of five amino acids, whereas the same amino acids showed negative correlations with phosphocholine, a membrane phospholipid precursor. MMCA in conjunction with transcriptome analysis has opened a new window into the metabolome.

Noninvasive phosphorus magnetic resonance spectroscopic imaging predicts outcome to first-line chemotherapy in newly diagnosed patients with diffuse large B-cell lymphoma

RATIONALE AND OBJECTIVES

Based on their association with malignant proliferation, using noninvasive phosphorus MR spectroscopic imaging ((31)P MRSI), we measured the tumor content of the phospholipid-related phosphomonoesters (PME), phosphoethanolamine and phospholcholine, and its correlation with treatment outcome in newly diagnosed patients with diffuse large B-cell lymphoma (DLBCL) receiving standard first-line chemotherapy.

EXPERIMENTAL DESIGN

The PME value normalized to nucleoside triphosphates (PME/NTP) was measured using (31)P MRSI in tumor masses of 20 patients with DLBCL before receiving standard first-line chemotherapy. Response at 6 months was complete in 13 patients and partial in seven. Time to treatment failure (TTF) was ≤11 months in eight patients, from 18 to 30 months in three, and ≥60 months in nine.

RESULTS

On a t test, the pretreatment tumor PME/NTP mean value (SD, n) of patients with a complete response at 6 months was 1.42 (0.41, 13), which was significantly different from the value of 2.46 (0.40, 7) in patients with partial response (P < .00001). A Fisher test significantly correlated the PME/NTP values with response at 6 months (sensitivity and specificity at 0.85, P < .004) while a Cox proportional hazards regression significantly correlated the PME/NTP values with TTF (hazard ratio = 5.21, P < .02). A Kaplan-Meier test set apart a group entirely composed of patients with TTF ≤ 11 months (hazard ratio = 8.66, P < .00001).

CONCLUSIONS

The pretreatment tumor PME/NTP values correlated with response to treatment at 6 months and time to treatment failure in newly diagnosed patients with DLBCL treated with first-line chemotherapy, and therefore they could be used to predict treatment outcome in these patients.

Paraoesophageal splenosis: An unusual differential of mediastinal soft tissue deposits

Ectopic splenic tissue can present as accessory spleens and splenosis. While accessory spleens are congenital and more common; splenosis occurs as a result of implantation of splenic tissue as a result of trauma or iatrogenic injury. Only up to 40 intrathoracic splenosis have been reported in the English language literature to date. Here we discuss a case in which Para oesophageal pre-aortic ectopic splenic tissue was identified through radionuclide imaging 20 years after splenic rupture in a 44-year-old male for work up of epigastric pain. Splenosis should be considered as differential diagnosis in all previously splenectomised patients who present with unexplained masses on imaging. Early diagnoses with preoperative non-invasive radionucleotide scanning with collateral histories can prevent unnecessary surgery and reduce expensive and invasive investigations.

Effects of HSP90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) on NEU/HER2 overexpressing mammary tumours in MMTV-NEU-NT mice monitored by Magnetic Resonance Spectroscopy

BACKGROUND

The importance of ERBB2/NEU/HER2 in the response of breast tumours to the heat shock protein 90 (HSP90) inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG; tanespimycin) has been demonstrated in the clinic. ERBB2 is an oncoprotein client that is highly dependent on HSP90. This and other oncogenic client proteins (e.g. B-RAF, C-RAF, ALK and CDK4) are depleted by 17-AAG in both animal tumours and patients. Here we investigate by Magnetic Resonance Spectroscopy (MRS) the metabolic response of 17-AAG in spontaneous, NEU/HER2 driven mammary tumours in transgenic MMTV-NEU-NT mice and in cells isolated and cultured from these tumours.

METHODS

Mammary tumours were monitored by 31P MRS in vivo and in tumour extracts, comparing control and 17-AAG treated mice. A cell line derived from NEU/HER2 mammary tumours was also cultured and the effect of 17-AAG was measured by 31P MRS in cell extracts. Molecular biomarkers were assessed by immunoblotting in extracts from cells and tumours. For comparison of tumour volume, metabolite concentrations and Western blot band intensities, two-tailed unpaired t-tests were used.

RESULTS

The NEU/HER2 mammary tumours were very sensitive to 17-AAG and responded in a dose-dependent manner to 3 daily doses of 20, 40 and 80mg/kg of 17-AAG, all of which caused significant regression. At the higher doses, 31P MRS of tumour extracts showed significant decreases in phosphocholine (PC) and phosphoethanolamine (PE) whereas no significant changes were seen at the 20mg/kg dose. Extracts of isolated cells cultured from the mammary carcinomas showed a significant decrease in viable cell number and total PME after 17-AAG treatment. Western blots confirmed the expected action of 17-AAG in inducing HSP72 and significantly depleting HSP90 client proteins, including NEU/HER2 both in tumours and in isolated cells.

CONCLUSIONS

The data demonstrate the high degree of sensitivity of this clinically relevant NEU/HER2-driven tumour model to HSP90 inhibition by 17-AAG, consistent with the clinical data, and suggest that the metabolic signature of choline phospholipids obtained by MRS could be useful both as a preclinical and clinical tool for investigating surrogate markers of response to treatment.

Can localised (19)F magnetic resonance spectroscopy pharmacokinetics of 5FU in colorectal metastases predict clinical response?

BACKGROUND

5-Fluorouracil remains widely used in colorectal cancer treatment more than 40 years after its development. 19F magnetic resonance spectroscopy can be used in vivo to measure 5FU's half-life and metabolism to cytotoxic fluoronucleotides. Previous studies have shown better survival associated with longer 5FU tumour half-life. This work investigated 5FU pharmacokinetics in liver metastases of colorectal cancer.

METHODS

A total of 32 subjects with colorectal cancer undergoing 5FU treatment, 15 of whom had liver metastases, were examined in a 1.5T MRI scanner, using a large coil positioned over the liver. Non-localised spectra were acquired in 1-min blocks for 32 min after injection of a 5FU bolus. The 5FU half-life was measured in each subject, and averaged spectra were examined for the presence of fluoronucleotides. Associations with progression-free survival were assessed.

RESULTS

No association was observed between 5FU half-life, tumour burden and survival. Half-lives were all shorter than those associated with improved survival in the literature. Remarkably, in the group with liver metastases, high levels of fluoronucleotides were associated with poorer survival; this counterintuitive result may be due to the higher levels of fluoronucleotides (whose level is higher in tumour tissue than in normal liver) in patients with higher tumour burdens.

CONCLUSIONS

It is recommended that future studies use chemical shift imaging at higher field strengths to better resolve tumour from normal liver. Non-localised spectroscopy retains prognostic potential by enabling straightforward detection of fluoronucleotides, which are present at very low concentrations distributed throughout the tissue.

Non-operative management of non-destructive extra-peritoneal rectal injury

This is a case report of extra-peritoneal rectal injury, secondary to a gunshot, that was managed non-operatively. A 57-year old male presented with a single gunshot to the right buttock and had blood per rectum. Extra-peritoneal rectal injuries were seen on proctoscopy and he had no genitourinary injury. He was managed successfully without rectal injury repair orfaecal stream diversion.

Adaptation to HIF-1 deficiency by upregulation of the AMP/ATP ratio and phosphofructokinase activation in hepatomas

BACKGROUND

HIF-1 deficiency has marked effects on tumour glycolysis and growth. We therefore investigated the consequences of HIF-1 deficiency in mice, using the well established Hepa-1 wild-type (WT) and HIF-1β-deficient (c4) model. These mechanisms could be clinically relevant, since HIF-1 is now a therapeutic target.

METHODS

Hepa-1 WT and c4 tumours grown in vivo were analysed by 18FDG-PET and 19FDG Magnetic Resonance Spectroscopy for glucose uptake; by HPLC for adenine nucleotides; by immunohistochemistry for GLUTs; by immunoblotting and by DIGE followed by tandem mass spectrometry for protein expression; and by classical enzymatic methods for enzyme activity.

RESULTS

HIF-1β deficient Hepa-1 c4 tumours grew significantly more slowly than WT tumours, and (as expected) showed significantly lower expression of many glycolytic enzymes. However, HIF-1β deficiency caused no significant change in the rate of glucose uptake in c4 tumours compared to WT when assessed in vivo by measuring fluoro-deoxyglucose (FDG) uptake. Immunohistochemistry demonstrated less GLUT-1 in c4 tumours, whereas GLUT-2 (liver type) was similar to WT. Factors that might upregulate glucose uptake independently of HIF-1 (phospho-Akt, c-Myc) were shown to have either lower or similar expression in c4 compared to WT tumours. However the AMP/ATP ratio was 4.5 fold higher (p < 0.01) in c4 tumours, and phosphofructokinase-1 (PFK-1) activity, measured at prevailing cellular ATP and AMP concentrations, was up to two-fold higher in homogenates of the deficient c4 cells and tumours compared to WT (p < 0.001), suggesting that allosteric PFK activation could explain their normal level of glycolysis. Phospho AMP-Kinase was also higher in the c4 tumours.

CONCLUSIONS

Despite their defective HIF-1 and consequent down-regulation of glycolytic enzyme expression, Hepa-1 c4 tumours maintain glucose uptake and glycolysis because the resulting low [ATP] high [AMP] allosterically activate PFK-1. This mechanism of resistance would keep glycolysis functioning and also result in activation of AMP-Kinase and growth inhibition; it may have major implications for the therapeutic activity of HIF inhibitors in vivo. Interestingly, this control mechanism does not involve transcriptional control or proteomics, but rather the classical activation and inhibition mechanisms of glycolytic enzymes.

Effects of HIF-1alpha and HIF2alpha on Growth and Metabolism of Clear-Cell Renal Cell Carcinoma 786-0 Xenografts

In cultured clear-cell renal carcinoma (CCRCC) 786-0 cells transfected with HIF1alpha (HIF-1+), HIF-2alpha (HIF-2+), or empty vector (EV), no significant differences were observed in the growth rates in vitro, but when grown in vivo as xenografts HIF-2alpha significantly increased, and HIF-1alpha significantly decreased growth rates, compared to EV tumors. Factors associated with proliferation were increased and factors associated with cell death were decreased in HIF-2+ tumors. Metabolite profiles showed higher glucose and lower lactate and alanine levels in the HIF-2+ tumors whilst immunostaining demonstrated higher pyruvate dehydrogenase and lower pyruvate dehydrogenase kinase 1, compared to control tumors. Taken together, these results suggest that overexpression of HIF-2alpha in CCRCC 786-0 tumors regulated growth both by maintaining a low level of glycolysis and by allowing more mitochondrial metabolism and tolerance to ROS induced DNA damage. The growth profiles observed may be mediated by adaptive changes to a more oxidative phenotype.

Restricted permeability of rat liver for glutamate and succinate

1. When rat liver slices were incubated aerobically with [U-(14)C]glutamate the concentration of (14)C within the slices remained lower (about 50%) than in the medium. The maximal concentration of (14)C in the liver was reached within minutes. In rat kidney-cortex slices by contrast, (14)C reached concentrations more than six times those of the medium. 2. In both liver and kidney (14)C appeared in the respiratory CO(2), indicating penetration of glutamate carbon into the mitochondria. In kidney slices the rate of glutamate oxidation per unit weight was about five times that in liver slices. 3. Taking into account the conversion of glutamate into glucose that occurs in the kidney but not in the liver, the flux rates of glutamate through the kidney were calculated to be about 15 times those through the liver when the external glutamate concentration was 5mm. 4. Anaerobically the glutamate concentrations in medium and tissue rapidly became equal in both liver and kidney. Thus the maintenance of concentration gradients depended on the expenditure of energy. 5. [U-(14)C]Succinate behaved similarly to glutamate. [U-(14)C]Serine was taken up more rapidly by the kidney than by the liver slices, but the concentrations reached in the liver did not remain below those of the medium. [(14)C]Urea was distributed evenly between medium and tissue water. 6. Incubation of liver slices with [(3)H]inulin indicated an extracellular space of liver slices of 26%. 7. When glutamate was generated within liver slices or the perfused liver on addition of oxaloacetate, pyruvate and a source of nitrogen, the concentration of glutamate in the tissue after 1hr. was 70-97 times that in the medium. Thus the exit of glutamate from the liver cell, like its entry, is restricted. This is borne out by measurements of the specific activity of extra- and intra-cellular glutamate on addition of [U-(14)C]glutamate medium. 8. Liver homogenates removed added glutamate and dicarboxylic acids 20-30 times as fast as did the perfused liver. 9. It is concluded that a major permeability barrier restricts the entry and exit through the outer liver cell membrane.

Abstract A224: Noninvasive PD markers of a pyruvate dehydrogenase kinase inhibitor, dichloroacetate, in human colon carcinoma xenografts

Pyruvate dehydrogenase (PDH) is the key mitochondrial enzyme that determines whether pyruvate formed during glycolysis from glucose will be metabolised to lactate or oxidised in the TCA cycle. Its regulator, pyruvate dehydrogenase kinase (PDK) negatively regulates PDH by phosphorylation. Dichloroacetate (DCA) is an inhibitor of PDK and treatment with DCA decreased proliferation and growth in cancer cells and solid tumors (1). The aim of this work was to develop a non-invasive and robust pharmacodynamic (PD) biomarker for tumor response following PDK inhibition.

Human HT29 (colon) carcinoma xenografts were examined using in vivo1H- and 31P- magnetic resonance spectroscopy (MRS), before and after 3 days of DCA treatment (200mg/kg via po). Controls were treated with vehicle alone (water). Metabolic profiles of tumor extracts were measured by high resolution in vitro 1H- and 31P-MRS.

Significant tumor growth inhibition (p&lt;0.001) was observed in HT29 xenografts following 3 days of DCA treatment when compared with vehicle-treated controls. In vivo, significant decreases in ratios of phosphomonoester/total phosphorus signal (P=0.01) and total choline/water signal (P=0.05) were found in DCA-treated HT29 xenografts. The in vivo results were confirmed by significantly lower phosphocholine (PC) (P=0.02), glycerophosphocholine (P=0.01) and glycerophosphoethanolamine (P=0.05) levels, as found by 31P-MRS of tumor extracts from DCA treated animals when compared with controls. Increases in leucine (P=0.04), iso-leucine (P=0.02), valine (P=0.04) and succinate levels (P=0.03) and lower ATP (P=0.003), glucose (P=0.03) and creatine (P=0.05) levels were also found in DCA-treated HT29 tumor extracts when compared with controls.

The drop in PC and other choline-related metabolites following DCA treatment is probably due to tumor stasis caused by the PDK inhibition, since DCA upregulates the mitochondrial membrane potential, induces apoptosis, decreases proliferation and inhibits tumor growth (1). These and the non-phospholipid changes in the metabolic profiles including lower ATP are consistent with previous findings where similar metabolic profiles were associated with antiangiogenic effects induced by LAQ824 (2).

The phospholipid changes may have potential as surrogate non-invasive markers for determining tumor response following treatment with DCA or other PDK inhibitors.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A224.

Abstract A228: Noninvasive magnetic resonance spectroscopic PD markers of a minor-groove interstrand cross-linking agent (BN2629) in human colon carcinoma and melanoma xenografts

BN2629 (also known as SJG-136) is a novel pyrrolobenzodiazepine dimer analogue that binds covalently in the minor groove of DNA, inducing little or no distortion of the double helix. Hence, it evades the p53-mediated detection and up-regulation of nucleotide excision repair mechanisms but induces apoptosis. It has just completed Phase 1 clinical trials in the USA (NCI) and UK (CR-UK), and has been approved by the NCI for Phase II evaluation.

The aim of this work was to develop a robust and non-invasive surrogate marker for tumor response following BN2629 treatment. We carried out an in vivo 31phosphorus magnetic resonance spectroscopy (31P MRS) study of BN2629 (80 g/kg via ip for 3 days) and vehicle in HT29 human colon carcinoma and LOX IMVI melanoma xenograft models. In vitro 31P MRS were performed on tumor extracts.

Significant growth delays (p&lt;0.0001) were observed in both BN2629-treated HT29 and LOX IMVI xenografts when compared with controls. In vivo31P MRS of the HT29 xenografts showed an increase in the phosphomonoester/total phosphorus signals (PME/TotP) (p=0.04) and PME/ - NTP ratios (p&lt;0.02) after 3 days of BN2629 treatment. No significant changes were observed in the control group. In vitro 31P MRS of extracts from BN2629-treated HT29 tumors showed significant increases in phosphoethanolamine (PE; p&lt;0.01), glycerophosphocholine (GPC; p&lt;0.01) and glycerophosphoethanolamine (GPE; p&lt;0.03) when compared with controls.

In vivo 31P MRS of the LOX IMVI xenografts showed an increase in - NTP/TotP ratio ( -NTP/TotP) (p&lt;0.01) after 3 days of BN2629 treatment. No significant changes were observed in the control group. In vitro 31P MRS of extracts from BN2629-treated LOX IMVI tumors showed significant increases in GPC (p&lt;0.001), GPE (p&lt;0.01) and ATP (p=0.04) when compared with controls.

Treatment with BN2629 resulted in tumor growth delay and altered bioenergetic and phospholipid metabolism in vivo, which are consistent with metabolic changes observed following treatment with agents such as 5-FU [1] and cyclophosphamide [2]. The phospholipid changes may be associated with alteration in membrane turnover following treatment, and these changes may have potential as surrogate non-invasive markers for determining tumor response following treatment with BN2629.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A228.

Combined metabolomic and proteomic analysis of human atrial fibrillation

OBJECTIVES

We sought to decipher metabolic processes servicing the increased energy demand during persistent atrial fibrillation (AF) and to ascertain whether metabolic derangements might instigate this arrhythmia.

BACKGROUND

Whereas electrical, structural, and contractile remodeling processes are well-recognized contributors to the self-perpetuating nature of AF, the impact of cardiac metabolism upon the persistence/initiation of this resilient arrhythmia has not been explored in detail.

METHODS

Human atrial appendage tissues from matched cohorts in sinus rhythm (SR), from those who developed AF post-operatively, and from patients in persistent AF undergoing cardiac surgery were analyzed using a combined metabolomic and proteomic approach.

RESULTS

High-resolution proton nuclear magnetic resonance (NMR) spectroscopy of cardiac tissue from patients in persistent AF revealed a rise in beta-hydroxybutyrate, the major substrate in ketone body metabolism, along with an increase in ketogenic amino acids and glycine. These metabolomic findings were substantiated by proteomic experiments demonstrating differential expression of 3-oxoacid transferase, the key enzyme for ketolytic energy production. Notably, compared with the SR cohort, the group susceptible to post-operative AF showed a discordant regulation of energy metabolites. Combined principal component and linear discriminant analyses of metabolic profiles from proton NMR spectroscopy correctly classified more than 80% of patients at risk of AF at the time of coronary artery bypass grafting.

CONCLUSIONS

The present study characterized the metabolic adaptation to persistent AF, unraveling a potential role for ketone bodies, and demonstrated that discordant metabolic alterations are evident in individuals susceptible to post-operative AF.

Suppression of HOX A cluster genes inhibits proliferation and induces cell death in human mixed-lineage leukemias

14020

Background: Leukemias harboring translocations of the mixed lineage leukemia locus (MLL) are generally associated with poor clinical prognosis. Using gene expression profiling we and others have previously shown that Homeobox (HOX) A cluster genes are highly expressed in leukemias with MLL rearrangements. Methods: Here we studied the role of aberrant HOXA9 expression in human MLL- rearranged and non-rearranged leukemias utilizing an shRNA mediated knockdown approach. Results: Three different shRNA constructs targeting human HOXA9 were synthesized and stably introduced into t(9;11) MOLM14 cells utilizing a lentiviral vector system. 75–80% HOXA9 RNA knockdown was confirmed by quantitative PCR and Western Blot analysis. In a panel of 17 AML/ALL cell lines (7 MLL rearranged, 10 non rearranged), HOXA9 directed shRNA inhibited cell proliferation starting as early as 48h after transduction, and induced apoptosis beginning at 72h. Interestingly, impaired cell proliferation and induction of apoptosis was significantly higher in the MLL rearranged cell lines (mean viability: 51.88%) than in the non-rearranged cells (mean viability: 90.98%; p=0.007) and also significantly correlated with the baseline HOXA9 mRNA expression before knockdown (R= 0.8, p=0.00017). We then further analyzed the effect of HOXA9 knockdown in MLL rearranged and non-rearranged primary human AML cells. Similar to our findings in cell lines, a marked induction of cell death was observed, which was significantly higher in leukemias with an MLL translocation (p=0.005) and also significantly correlated with the baseline HOXA9 mRNA expression (R= 0.8, p=0.001). Next, the in vivo effect of HOXA9 knockdown was assessed by transplanting luciferase-expressing SEMK2 (t4;11) cells into SCID-beige mice followed by in vivo bioluminescent imaging. Leukemia burden was significantly reduced in HOXA9 shRNA treated mice (n=10) with a peak difference at day 15 (p=0.000059) shortly before mice of the control group (n=10) succumbed from overt leukemia. At this point all mice of the HOXA9 shRNA treated group were still healthy with no signs of leukemia. Conclusions: Taken together our data implicates that depletion of HOXA9 might be a novel approach for targeted therapy in human MLL rearranged leukemias.

No significant financial relationships to disclose.

Glut-1 as a therapeutic target: increased chemoresistance and HIF-1-independent link with cell turnover is revealed through COMPARE analysis and metabolomic studies

The facilitative glucose transporter Glut-1 is overexpressed and confers poor prognosis in a wide range of solid tumours. The peri-necrotic pattern of expression often seen in human tumour samples is linked with its transcriptional control in hypoxic conditions by hypoxia-inducible factor HIF-1 or through a reduced rate of oxidative phosphorylation. Hypoxia-regulated genes offer promise as novel therapeutic targets as a means of preventing the proliferation and eventual metastatic spread of tissue originating from residual chemically and radio resistant hypoxic cells that have survived treatment. Inhibiting the expression or functionality of Glut-1 may be a way of specifically targeting hypoxic cells within the tumour that depend upon a high rate of glucose uptake for anaerobic glycolysis. We used an array of formalin-fixed, paraffin-embedded samples of the NCI-60 panel of cell lines to carry out immunohistochemical detection of Glut-1 and to select possible candidate lead compounds by COMPARE analysis with agents from the NCI diversity screen, which may work via inhibition of Glut-1 or Glut-1-dependent processes. "Positive" COMPARE hits were mostly conjugated Pseudomonas toxins binding the epidermal growth factor receptor (EGFR). However, correlations with standard anticancer agents were virtually all negative, indicating a link between Glut-1 and chemoresistance. MTT proliferation assays carried out using stable, Glut-1 overexpressing cell lines generated from the bladder EJ138, human fibrosarcoma HT 1080 and the hepatoma wild type Hepa and HIF-1B-deficient c4 tumour cell lines revealed a cell line-dependent increase in chemoresistance to dacarbazine, vincristine and the bioreductive agent EO9 in Glut-1 overexpressing EJ138 relative to WT and empty vector controls. Metabolomic analysis ((31)P-MRS and (1)H MRS) carried out using cell lysates and xenografts generated from Glut-1 overexpressing Hepa and c4 cell lines showed higher glucose levels in Glut-1 overxpressing c4 relative to parental tumour extracts occurred in the absence of an increase in lactate levels, which were in turn significantly higher in the Glut-1 overexpressing Hepa xenografts. This implies that Glut-1 over-expression without a co-ordinate increase in HIF-1-regulated glycolytic enzymes increases glucose uptake but not the rate of glycolysis. Glut-1 overexpressing xenografts also showed higher levels of phosphodiester (PDE), which relates to the metabolite turnover of phospholipids and is involved in membrane lipid degradation, indicating a mechanism by which Glut-1 may increase cell turnover.

In vivo 31P MR spectral patterns and reproducibility in cancer patients studied in a multi-institutional trial

The standardization and reproducibility of techniques required to acquire anatomically localized 31P MR spectra non-invasively while studying tumors in cancer patients in a multi-institutional group at 1.5 T are reported. This initial group of patients was studied from 1995 to 2000 to test the feasibility of acquiring in vivo localized 31P MRS in clinical MR spectrometers. The cancers tested were non-Hodgkin's lymphomas, sarcomas of soft tissue and bone, breast carcinomas and head and neck carcinomas. The best accrual and spectral quality were achieved with the non-Hodgkin's lymphomas. The initial analysis of the spectral values of the sum of phosphoethanolamine plus phosphocholine normalized by the content of nucleotide triphosphates in a homogeneous sample of 32 NHL patients studied by in vivo (31)P MRS showed good reproducibility among different institutions. No statistical differences were found between the institution with the largest number of cases accrued and the rest of the multi-institutional NHL data (2.28 +/- 0.64, mean +/- standard error; n = 17, vs 2.08 +/- 0.14, n = 15). The preliminary data reported demonstrate that the institutions involved in this trial are obtaining reproducible 31P MR spectroscopic data non-invasively from human tumors. This is a fundamental prerequisite for the international cooperative group to be able to demonstrate the clinical value of the normalized determination of phosphoethanolamine plus phosphocholine by 31P MRS as predictor for treatment response in cancer patients.

CCK2 gastrin receptor as a potential target for therapy in leukaemia cell lines

The gastrin CCK2 pathway has been implicated in the development of various cancers including leukaemia. An autocrine or intracrine pathway may exist in the leukaemia cell that is involved in stimulating proliferation. We tested four leukaemia cell lines, KU812, ML-1, MOLT-4 and U937 for the existence of the CCK2 receptor and gastrin precursor protein using immunoblotting. We also assessed the effect of CCK2 antagonist PD 135 and both gastrin 17 and glycine-extended gastrin on the proliferation of the cell lines. We found immunoreactive CCK2 and gastrin precursors present in all 4 cell lines. We also observed a stimulatory effect on proliferation by gastrin and glycine-extended gastrin on 2 and 3 of the cell lines respectively and an inhibitory effect of PD 135 on all 4 cell lines. These results demonstrate that the gastrin-gastrin receptor axis is a potential target for new therapeutic strategies.

The C-neu mammary carcinoma in Oncomice; characterization and monitoring response to treatment with herceptin by magnetic resonance methods

To characterize spontaneously occurring c-neu/HER2 overexpressing tumours in oncomice and their response to herceptin by non-invasive magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI). Oncomice were monitored by localized 31P MRS during unperturbed growth and before and after treatment with 10 mg/kg herceptin (Hoffman La Roche) intraperitoneally for up to 21 days post-treatment. Vascular morphology and function was assessed by quantitation of tumour magnetic resonance (MR) relaxation rates R2* and R2 prior to and either during carbogen (95% O2/5% CO2) breathing or following administration of the blood-pool contrast agent NC100150 (Clariscan, Amersham Health). Immunohistochemistry showed strong membrane staining for HER2 protein overexpression. The 31P MRS showed only a significant (p<0.01) increase of phosphomonoester / total phosphate ratio over 21 days of growth. Herceptin increased the tumour volume doubling time compared to untreated tumours and significantly increased the phosphomonoester / beta-nucleoside triphosphate ratio 2 days after treatment (p=0.01). Tumours showed a highly heterogeneous yet significant (p<0.01) decrease or increase in R2* in response to carbogen or NC100150 respectively. The absence of a decline in tumour bioenergetics with growth, commonly seen in 31P MRS studies of transplanted rodent tumour models, coupled with the heterogeneous blood volume revealed by 1H MRI, suggest a metabolic and vascular phenotype similar to that found in human tumours.

Investigations in vivo of the effects of carbogen breathing on 5-fluorouracil pharmacokinetics and physiology of solid rodent tumours

PURPOSE

We have shown previously that carbogen (95% 0(2), 5% CO(2)) breathing by rodents can increase uptake of anticancer drugs into tumours. The aim of this study was to extend these observations to other rodent models using the anticancer drug 5-fluorouracil (5FU). 5FU pharmacokinetics in tumour and plasma and physiological effects on the tumour by carbogen were investigated to determine the locus of carbogen action on augmenting tumour uptake of 5FU.

METHODS

Two different tumour models were used, rat GH3 prolactinomas xenografted s.c. into nude mice and rat H9618a hepatomas grown s.c. in syngeneic Buffalo rats. Uptake and metabolism of 5FU in both tumour models with or without host carbogen breathing was studied non-invasively using fluorine-19 magnetic resonance spectroscopy ((19)F-MRS), while plasma samples from Buffalo rats were used to construct a NONMEM pharmacokinetic model. Physiological effects of carbogen on tumours were studied using (31)P-MRS for energy status (NTP/Pi) and pH, and gradient-recalled echo magnetic resonance imaging (GRE-MRI) for blood flow and oxygenation.

RESULTS

In both tumour models, carbogan-induced GRE-MRI signal intensity increases of approximately 60% consistent with an increase in tumour blood oxygenation and/or flow. In GH3 xenografts, (19)F-MRS showed that carbogen had no significant effect on 5FU uptake and metabolism by the tumours, and (31)P-MRS showed there was no change in the NTP/Pi ratio. In H9618a hepatomas, (19)F-MRS showed that carbogen had no effect on tumour 5FU uptake but significantly ( p=0.0003) increased 5FU elimination from the tumour (i.e. decreased the t(1/2)) and significantly ( p=0.029) increased (53%) the rate of metabolism to cytotoxic fluoronucleotides (FNuct). The pharmacokinetic analysis showed that carbogen increased the rate of tumour uptake of 5FU from the plasma but also increased the rate of removal. (31)P-MRS showed there were significant ( p<or=0.02) increases in the hepatoma NTP/Pi ratio of 49% and transmembrane pH gradient of 0.11 units.

CONCLUSIONS

We suggest that carbogen can transiently increase tumour blood flow, but this effect alone may not increase uptake of anticancer drugs without a secondary mechanism operating. In the case of the hepatoma, the increase in tumour energy status and pH gradient may be sufficient to augment 5FU metabolism to cytotoxic FNuct, while in the GH3 xenografts this was not the case. Thus carbogen breathing does not universally lead to increased uptake of anticancer drugs.

Noninvasive Measurements of Capecitabine Metabolism in Bladder Tumors Overexpressing Thymidine Phosphorylase by Fluorine-19 Magnetic Resonance Spectroscopy

PURPOSE

Previous studies have shown that tumor response to capecitabine strongly correlates with tumor thymidine phosphorylase (TP). The aims of our study were to (a). investigate the pharmacological role of TP by measuring the pharmacokinetics (PK) of capecitabine in a human bladder tumor model that was characterized by the overexpression of TP and (b). develop the use of PK measurements for capecitabine by fluorine-19 magnetic resonance spectroscopy as a noninvasive surrogate marker for determining TP levels in tumors and for predicting tumor response to capecitabine in patients.

EXPERIMENTAL DESIGN

TP overexpressing (2T10) and control tumors were grown s.c. in nude mice. Mice were given a dose of capecitabine or 5'-deoxy-5-fluorouridine (5'DFUR). (19)F tumor spectra were acquired for determination of rate constants of capecitabine breakdown and buildup and subsequent breakdown of intermediates, 5'-deoxy-5-fluorocytidine (5'DFCR) and 5'DFUR. The rate constant of 5'DFUR breakdown was also evaluated.

RESULTS

The rate constant of breakdown of intermediates was significantly faster in 2T10 tumors than controls (P < 0.003). No significant differences in the rate of capecitabine breakdown or intermediate buildup were observed. The rate constant of 5'DFUR breakdown in the 2T10 tumors was doubled compared with controls (P < 0.001).

CONCLUSIONS

This study confirmed the expected pathway of capecitabine metabolism and showed that the level of TP was related to the rate of 5'DFUR conversion. Using in vivo fluorine-19 magnetic resonance spectroscopy to mea-sure the PK of capecitabine and its intermediate metabolites in tumors may provide a noninvasive surrogate method for determining TP levels in tumors and for predicting tumor response to capecitabine in patients.

Prevalence of chronic renal failure in the diabetic population at the University Hospital of the West Indies

The prevalence of chronic renal failure (CRF) in 460 patients with diabetes mellitus attending the diabetic outpatient clinic at the University Hospital of the West Indies in Jamaica was determined from a review of medical records. The prevalence of CRF was 10% (39/386) in the diabetic clinic population. Significant positive associations with CRF were found with male gender (20/98, 20% vs 19/287, 7%; odds ratio (OR), 3.24; p = 0.001); age 60 years and older (22/162; 14% vs 17/221, 8%; OR, 2.01; p = 0.04); fasting blood glucose concentrations exceeding 8.0 mmol/L (22/162, 13% vs 12/182, 7%; OR, 2.08; p = 0.05); the presence of significant proteinuria as a marker for outcome (13/39, 33% vs 48/346, 14%; OR, 3.60; p = 0.02) and peripheral vascular disease (6/20, 30% vs 139/386, 10%; OR, 4.75; p = 0.005). The prevalence of CRF did not differ significantly between patients with Type 1 and Type 2 diabetes mellitus. Also, the presence of CRF was not significantly associated with duration of diabetes mellitus, type of hypoglycaemic agents used, or history of hypertension. However, the presence of persistent proteinuria was significantly associated with duration of diabetes mellitus exceeding five years (46/255, 17% vs 11/149, 7%; OR, 2.52; p = 0.005) and a history of hypertension (41/235, 17% vs 20/198, 10%; OR, 1.88; p = 0.03) but not with age or gender. This study emphasizes the need to evaluate patients with diabetes mellitus for renal impairment so that intervention strategies may be adopted early to delay progression to endstage renal disease.

Magnetic Resonance Spectroscopic Pharmacodynamic Markers of the Heat Shock Protein 90 Inhibitor 17-Allylamino,17-Demethoxygeldanamycin (17AAG) in Human Colon Cancer Models

BACKGROUND

17-allylamino,17-demethoxygeldanamycin (17AAG) is a novel anticancer drug that inhibits heat shock protein 90 (Hsp90), resulting in proteasomal degradation of several oncogenic proteins. We used phosphorus magnetic resonance spectroscopy (31P-MRS) to determine whether 17AAG treatment leads to alterations in phospholipids that could serve as pharmacodynamic markers for tumor response to 17AAG.

METHODS

HCT116, HT29, and SW620 colon cancer cells were treated with 17AAG, and extracts were examined by 31P-MRS. HT29 cells were also treated with the active metabolite of 17AAG, 17-amino,17-demethoxygeldanamycin (17AG), or the inactive 17AAG analog NSC683666. MF-1 nude mice carrying HT29 xenografts were examined using in vivo 31P-MRS before and after 17AAG treatment; xenograft tumor extracts were examined by 31P-MRS and proton MRS (1H-MRS). Hsp90 client protein expression was determined by using western blots. Two-tailed t tests were used to compare metabolite concentrations and ratios, and a Mann-Whitney U test was used to compare proportions. All statistical tests were two-sided.

RESULTS

17AAG treatment led to statistically significantly increased phosphocholine levels in all three cell lines (P =.02). 17AG treatment also increased phosphocholine levels in HT29 cells, whereas NSC683666 had no effect. The phosphomonoester/phosphodiester ratio was statistically significantly increased in the HT29 xenografts after 17AAG treatment relative to the pretreatment ratio (P =.02), whereas no statistically significant change was observed after vehicle treatment (P =.62). Statistically significant increases in phosphocholine, phosphoethanolamine, and valine levels were also observed in tumor extracts treated with 17AAG.

CONCLUSIONS

Inhibition of Hsp90 by 17AAG resulted in altered phospholipid metabolism in cultured tumor cells and in tumor xenografts. The increases observed in phosphocholine and phosphomonoester levels suggest that these metabolites may have the potential to act as noninvasive pharmacodynamic markers for analyzing tumor response to treatment with 17AAG or other Hsp90 inhibitors.

Tumor vascular architecture and function evaluated by non-invasive susceptibility MRI methods and immunohistochemistry

PURPOSE

To investigate the physiological origins responsible for the varying blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) responses to carbogen (95% O(2)/5% CO(2)) breathing observed with different tumor types.

MATERIALS AND METHODS

Susceptibility contrast-enhanced MRI using the exogenous blood pool contrast agent NC100150 to determine blood volume and vessel size, and immunohistochemical-derived morphometric parameters, were determined in GH3 prolactinomas and RIF-1 fibrosarcomas, both grown in mice, which exhibited very different BOLD responses to carbogen.

RESULTS

Administration of NC100150 increased the R(2)* and R(2) rates of both tumor types, and indicated a significant four-fold larger blood volume in the GH3 tumor. The ratio deltaR(2)*/deltaR(2) showed that the capillaries in the GH3 were two-fold larger than those in the RIF-1, in agreement with morphometric analysis. Carbogen breathing induced a significant 25% decrease in R(2)* in the GH3 prolactinoma, whereas the response in the RIF-1 fibrosarcoma was negligible.

CONCLUSION

Low blood volume and small vessel size (and hence reduced hematocrit) are two reasons for the lack of R(2)* change in the RIF-1 with carbogen breathing. BOLD MRI is sensitive to erythrocyte-perfused vessels, whereas exogenous contrast agents interrogate the total perfused vascular volume. BOLD MRI, coupled with a carbogen challenge, provides information on functional, hemodynamic tumor vasculature.

Understanding the tumor metabolic phenotype in the genomic era

Now, at the beginning of a new century, 80 years after Warburg's Nobel prize winning discoveries, we are beginning to make sense of the underlying causes of the well known metabolic phenotype of tumor cells. Building on decades of research to understand the interrelationships between respiration and glycolysis in cancer, the tumor metabolic phenotype can now begin to be understood in a genomic context. With the discovery of hypoxia inducible factor-1 (HIF-1), which is widely overexpressed across a broad range of cancers, modern molecular tools have allowed us to put together the pattern of events that might explain the metabolic differences between tumor and normal cells. HIF-1 controls cellular and systemic responses to oxygen availability and coordinates up-regulation of genes involved in many pathways concerned with tumour growth and metabolism including angiogenesis, glucose and energy metabolism, cellular proliferation, differentiation and viability, apoptosis, pH regulation and matrix metabolism. These findings begin to explain how glucose uptake and glycolysis could be up-regulated in cancer cells (through binding to a core DNA recognition sequence) in a co-ordinated and constitutive fashion that may also allow us to elucidate new targets for tumor therapy.

Metabolic profiles of human brain tumors using quantitative in vivo 1H magnetic resonance spectroscopy

Proton spectroscopy can noninvasively provide useful information on brain tumor type and grade. Short- (30 ms) and long- (136 ms) echo time (TE) (1)H spectra were acquired from normal white matter (NWM), meningiomas, grade II astrocytomas, anaplastic astrocytomas, glioblastomas, and metastases. Very low myo-Inositol ([mI]) and creatine ([Cr]) were characteristic of meningiomas, and high [mI] characteristic of grade II astrocytomas. Tumor choline ([Cho]) was greater than NWM and increased with grade for grade II and anaplastic astrocytomas, but was highly variable for glioblastomas. Higher [Cho] and [Cr] correlated with low lipid and lactate (P < 0.05), indicating a dilution of metabolite concentrations due to necrosis in high-grade tumors. Metabolite peak area ratios showed no correlation with lipids and mI/Cho (at TE = 30 ms), and Cr/Cho (at TE = 136 ms) best correlated with tumor grade. The quantified lipid, macromolecule, and lactate levels increased with grade of tumor, consistent with progression from hypoxia to necrosis. Quantification of lipids and macromolecules at short TE provided a good marker for tumor grade, and a scatter plot of the sum of alanine, lactate, and delta 1.3 lipid signals vs. mI/Cho provided a simple way to separate most tumors by type and grade.

Issues in GRE & Se Magnetic Resonance Imaging to Probe Tumor Oxygenation

Tumor oxygenation determines the efficacy of radiotherapy, but there is no non-invasive way to image this parameter. Since gradient recalled echo (GRE) images are sensitive to blood deoxyhaemoglobin concentration ([dHb]) they could have a role in assessing tumor oxygenation. In brain, linear relationships have been demonstrated between brain tissue R2* relaxation rate and tissue [dHb] or oxygen saturation, but in tumors, vascular and tissue heterogeneity, and the presence of simultaneous oxidative and glycolytic metabolism, complicate the analysis. We have studied the effects of vascular challenge in a rat prolactinoma tumor model by MR imaging and spectroscopy and comment on the implications of these results for calibrating GRE images for blood or tissue pO2.

Enhanced uptake of ifosfamide into GH3 prolactinomas with hypercapnic hyperoxic gases monitored in vivo by (31)P MRS

Previously, (31)P magnetic resonance spectroscopy (MRS) has been used to detect ifosfamide (IF) in vivo and to show that breathing carbogen (5% CO(2)/95% O(2)) enhances the uptake and increases the efficacy of IF in rat GH3 prolactinomas [Rodrigues LM, Maxwell RJ, McSheehy PMJ, Pinkerton CR, Robinson SP, Stubbs M, and Griffiths JR (1997). In vivo detection of ifosfamide by (31)P MRS in rat tumours; increased uptake and cytotoxicity induced by carbogen breathing in GH3 prolactinomas. Br J Cancer 75, 62-68]. We now show that other hypercapnic and/or hyperoxic (5% CO(2) in air, 2.5% CO(2) in O(2)) gas mixtures also increase the uptake of IF into tumors, measured by (31)P MRS. All gases caused an increased uptake (C(max)) of IF compared to air breathing, with carbogen inducing the largest increase (85% (P<.02) compared to 46% with 2.5% CO(2) in O(2) (P<.004) and 48% with 5% CO(2) in air (P<.004)). The T(max) (time of maximum concentration in tumor posintravenous injection of IF) was significantly (P<.04) later in the cohort that breathed 5% CO(2) in air. The increased uptake of IF with carbogen breathing was selective to tumor tissue and there were no significant increases in any of the normal tissues studied, suggesting that any host tissue toxicity would be minimal. Carbogen breathing by patients causes breathlessness. There was no significant difference in IF uptake between breathing carbogen and 2.5% CO(2) in O(2) and, therefore, the ability of 2.5% CO(2) in O(2) to also increase IF uptake may be clinically useful as it causes less patient discomfort.

Magnetic Resonance Spectroscopy of cancer-practicalities of multi-centre trials and early results in non-Hodgkin's lymphoma

This review describes problems and solutions encountered in large scale multicentre trials of Magnetic Resonance Methods for monitoring cancer. It is illustrated with reference to the Multi-Institutional Group on Magnetic Resonance Spectroscopy (MRS) Applications to Cancer which was set up to perform a trial of 31P MRS for monitoring non-invasively chemotherapy of solid tumours. 31P MR spectra of non-Hodgkin's lymphoma (NHL) pre- and posttreatment, across nine Institutions, were acquired on either General Electric (GE) or Siemens 1.5T Clinical MR instruments. Development of the trial protocol, design of the Radio Frequency (RF) coils and Quality Control procedures necessary to ensure that the datasets acquired at each centre were comparable, are described. The data revealed that phosphomonoesters (PME)/nucleotide triphosphates (NTP) ratio decreased significantly after treatment in the Complete (P<0.001) and Partial (P<0.05) Responders but not in the Non-Responders (P>0.1). In addition, the PME/NTP ratio in the pre-treatment spectra correlated with the subsequent outcome of treatment indicating that PME/NTP levels are significant predictors of long-term clinical response and time-to-treatment failure in NHL.

Why are cancers acidic? A carrier-mediated diffusion model for H+ transport in the interstitial fluid

31P MRS studies have shown that the intracellular compartment ot tumours is kept near neutrality, whereas the interstitial fluid is acidic (pH 6.5-6.8). Why is this compartment acidic? Balance studies confirm that tumours produce excessive lactic acid, although less than usually supposed, but this cannot be the whole story, since Tannock and co-workers have shown interstitial acidity in glycolysis-deficient tumours. Another major acid load is caused by hydration of CO2 molecules to carbonic acid, catalysed by carbonic anhydrase. The distance that H+ must diffuse from cancer cells to capillaries is further than in normal tissue and this will increase acidification near the cells. We show that previous quantitative models based on simple H+ diffusion are unsatisfactory. This is because most H+ ions cross the interstitial space bound to buffers such as inorganic phosphate. Although these protonated buffers (i.e. conjugate acids) diffuse much more slowly than H+ ions they carry most of the protons, so the pH predicted by this model is closer to neutrality for a given proton production rate than that predicted by the dissolved H+ model. We have developed a mathematical model of this carrier-mediated system that predicts pHe values as low as those observed in some tumours.

Metabolic changes detected by in vivo magnetic resonance studies of HEPA-1 wild-type tumors and tumors deficient in hypoxia-inducible factor-1beta (HIF-1beta): evidence of an anabolic role for the HIF-1 pathway

Hypoxia-inducible factor-1 (HIF-1) regulates many pathways potentially important for tumor growth, including angiogenesis and glycolysis. Most attention has focused on its role in the response to hypoxia, but HIF-1 is also constitutively expressed in many tumors. To analyze the role of this pathway in vivo, we used magnetic resonance (MR) methods and complementary techniques to monitor metabolic changes in tumors derived from HEPA-1 mouse hepatoma lines that were either wild type (WT) or deficient in hypoxia-inducible transcription factor HIF-1beta (c4). The c4 tumors grew significantly more slowly than the WT tumors (P < 0.05), but were examined at a similar size (0.4-0.6 g). At the tumor size used in these studies, no differences in vascularity were observed, and MR parameters measured that related to tumor blood flow, vascularity, and oxygenation demonstrated no significant differences between the two tumor types. Unexpectedly, the ATP content of the c4 tumor was approximately 5 times less than in the WT tumor [measured in tumor extracts (P < 0.001) and by metabolic imaging (P < 0.05)]. Noninvasive (31)P MR spectroscopy showed that the nucleoside triphosphate/P(i) ratio of the two tumor types was similar, so the low ATP content of the c4 tumors was not caused by (or a cause of) impaired cellular bioenergetics. Rather, glycine, an essential precursor for de novo purine formation, was significantly lower in the c4 tumors (P < 0.05), suggesting that ATP synthesis was impaired in the mutant tumor cells. Supporting evidence for this hypothesis came from the significantly lower concentrations of betaine, phosphocholine, and choline in the c4 tumors (P < 0.05); these are intermediates in an alternative pathway for glycine synthesis. No significant differences were seen in lactate or glucose content. MR resonances from phosphodiesters, which relate to the metabolic turnover of phospholipid membranes, were significantly lower in the WT tumors than in the c4 tumors, both in vivo (P < 0.05) and in extracts (P < 0.01). We propose that loss of up-regulation of expression of the genes for glucose transporters and glycolytic enzymes in the c4 tumors decreased formation of glycine, an essential precursor of ATP synthesis, and thus caused the low ATP content of the c4 tumors. In summary, these data suggest that disruption of the HIF-1 pathway in these tumor cells impairs the supply of anabolic precursors required for cell synthesis. They suggest potential biochemical targets that may be modified by therapy blocking HIF-1 function.

Issues of normal tissue toxicity in patient and animal studies--effect of carbogen breathing in rats after 5-fluorouracil treatment

Non-invasive magnetic resonance spectroscopy (MRS) can be used in the clinic to monitor the pharmacokinetics of the chemotherapeutic drug 5-fluorouracil (5-FU) and the effects of modifiers. We report two studies of 5-FU toxicity in normal tissue--one with patients and the other an animal study. 1) 19F MRS signals from fluoronucleotides, cytotoxic anabolites of 5-FU metabolism, were observed in the livers of two patients treated with 5-FU for colorectal cancer, shown by computed tomography (CT) and ultrasound (US) to have no liver metastases. This is the first report of non-invasive monitoring of toxic 5-FU metabolites in normal human tissues. 2) In animals, carbogen-breathing enhances tumour uptake and the efficacy of 5-FU, and the method is under trial in patients. This study demonstrates that there were no significant effects of carbogen breathing on the levels of 5-FU and its metabolites in normal rat tissues, or on the histology of the tissues assessed after treatment.

Issues in flow and oxygenation dependent contrast (FLOOD) imaging of tumours

The sensitivity of blood oxygenation level dependent (BOLD) contrast techniques to changes to tumour deoxyhaemoglobin concentration is of relevance to many strategies in cancer treatments. In the context of tumour studies, which frequently involve the use of agents to modify blood flow, there are underlying physiological changes different to those of BOLD in the brain. Hence we use the term, flow and oxygenation dependent (FLOOD) contrast, to emphasize this difference and the importance of flow effects. We have measured the R(2)* changes in a prolactinoma tumour model for a variety of vasoactive challenges [carbogen, 100% oxygen and 100% nitrogen as different breathing gases, and administration of tumour blood flow modifiers such as calcitonin gene related peptide (CGRP), hydralazine and nicotinamide]. In addition we have measured other relevant physiological parameters, such as bioenergetic status from (31)P MRS, and blood pH and glucose, that may change during a vasoactive challenge. Here we discuss how they relate to our understanding of FLOOD contrast in tumours. We frequently observe R(2)* changes that match the expected action of the vascular stimulus: R(2)* decreases with agents expected to improve tumour oxygenation and blood flow, and increases with agents designed to increase tumour hypoxia. Unlike most normal tissues, tumours have a chaotic and poorly regulated blood supply, and a mix of glycolytic and oxidative metabolism; thus the response to a vasoactive challenge is not predictable. Changes in blood volume can counteract the effect of blood oxygenation changes, and changes in blood pH and glucose levels can alter oxygen extraction. This can lead to R(2)* changes that are smaller or the reverse of those expected. To properly interpret FLOOD contrast changes these effects must be accounted for.

Transport of peptidomimetic thrombin inhibitors with a 3-amidino-phenylalanine structure: permeability and efflux mechanism in monolayers of a human intestinal cell line (Caco-2)

PURPOSE

Peptidomimetic thrombin inhibitors derived from Nalpha-(2-naphthylsulfonyl)-3-amidino-phenylalanine with different basic and acidic substituents were investigated with respect to their intestinal transport behavior.

METHODS

Intestinal permeability coefficients were studied using Caco-2 monolayers and a reversed-phase HPLC method for quantitation.

RESULTS

Apparent permeability coefficients Papp of compounds with a free amidino group were in general low (<10 x 10(-8) cm/s) and independent of the structure of the amide part (C-terminus). Polarized efflux, however, was strongly affected by substituents in the amide moiety yielding the following efflux ratios (ER): methylpiperidide (1) (ER 45) > piperidine carboxylic acid methylester (ER 6-11) > piperidine carboxylic acids (ER 1.9-2.9) > piperazide (ER -0.17). Efflux of (1) was temperature-dependent, but independent of the enantiomeric configuration, accompanied by an increase in transepithelial electrical resistance (TEER), and could be reduced by P-gp inhibitors (PSC 833, Cremophor EL) but not by indomethacin. Replacement of the amidine group of (1) by aminomethyl-, amino-, and oxamidine- moieties drastically increased absorptive permeability (46-68 fold) with ER < 3.4. In contrast, the oxamidine with a C-terminal nipecotic acid residue (8) displayed also a temperature dependent efflux- without altering TEER (ER 22). This efflux was sensitive to PSC833/Cremophor EL and indomethacin.

CONCLUSIONS

Basic and acidic residues of amidino-phenylalanine-derived thrombin inhibitors mediate affinity to intestinal efflux pumps. presumably P-gp and MRP. P-gp mediated efflux was related to a net positive charge and accompanied by an increased TEER. Among the methylpiperide (1) promoieties studied the oxamidino group seems to be very promising in overcoming both transport and efflux problems frequently encountered with peptidomimetics containing amidines.

The life and work of Dermot Hedley ("Derek") Williamson (1929-1998)

Derek Williamson's scientific career spanned the "Golden Age" of research into metabolic regulation, to which he made an important and sustained contribution. Derek joined Hans Krebs' laboratory at Sheffield University in 1946 and moved to Krebs' MRC Unit in Oxford in 1960. He elaborated an enzymic method for the determination of acetoacetate and 3-hydroxybutyrate [Williamson, Mellanby and Krebs, Biochem. J. (1962) 82, 90-96], which opened up the field of ketone body metabolism and its regulation and became a Citation Classic. Another Citation Classic followed [Williamson, Lund and Krebs, Biochem. J. (1967) 103, 514-527]. He moved with Krebs to the Metabolic Research Laboratory at the Radcliffe Infirmary in 1967, where he blossomed, formulating his ideas about the integrated regulation of metabolic pathways, particularly with regard to fatty acid oxidation, lipid synthesis and ketone body metabolism. His success was illustrated by more than 200 publications. Derek implanted and nurtured a sense of the excitement of scientific discovery in his colleagues and students, and he worked hard to provide a friendly, supportive and encouraging environment. Many lives have been enriched by the privilege of working with him.

Learning to network and networking to learn: facilitating the process of adaptive management in a local response to the UK's National Air Quality Strategy

The adaptive management leitmotiv of "learning to manage and managing to learn" sets out an attractive agenda for dealing with the overwhelming complexity of environmental phenomena that humans have problematized. To ensure that this rallying cry translates into effective action, it is important to give consideration to structures and procedures for facilitating the efforts of those willing or able to respond to the adaptive management call. To date, calls to establish the right organization to coordinate multiagency responses have tended to emphasize the noun, or bounded-entity, sense of the word organization. We believe that this is at the expense of its other, verb or process, connotation. In this paper, rather than searching for the perfect organization structure that mandates mutual trust and collective action shaped by all relevant parties' perspectives and possible contributions, we direct attention towards the process of nurturing integrated adaptive responses among individuals who have diverse organizational allegiances. By shifting the balance towards the process connotation of the right organization, we hope that a new mindscape can be discerned for those interested in putting adaptive management principles into practice. We seek to conjure up an image of this mindscape through the phrase "learning to network and networking to learn," and set out to strengthen this by demonstrating how adaptive response networks can arise from the mutually defining relationship between stakeholders and issues. This is demonstrated through a local response to the United Kingdom's National Air Quality Strategy.

A protocol for the dental management of von Willebrand's disease, haemophilia A and haemophilia B

A guide for the dental management of the three inherited bleeding disorders, von Willebrand's disease, haemophilia A and haemophilia B, was established jointly by the Institute of Medical and Veterinary Science Transfusion and Haemostasis Unit in conjunction with the Medically Compromised Dental Unit at the Adelaide Dental Hospital. This protocol was subjected to a successful trial for 24 months.