Tumor Glucose Uptake Research Articles

The cell cycle regulator 14-3-3σ opposes and reverses cancer metabolic reprogramming.

SummaryExtensive reprogramming of cellular energy metabolism is a hallmark of cancer. Despite its importance, the molecular mechanism controlling this tumour metabolic shift remains not fully understood. Here we show that 14-3-3σ regulates cancer metabolic reprogramming and protects cells from tumourigenic transformation. 14-3-3σ opposes tumour-promoting metabolic programs by enhancing c-Myc poly-ubiquitination and subsequent degradation. 14-3-3σ demonstrates the suppressive impact on cancer glycolysis, glutaminolysis, mitochondrial biogenesis and other major metabolic processes of tumours. Importantly, 14-3-3σ expression levels predict overall and recurrence-free survival rates, tumour glucose uptake and metabolic gene expression in breast cancer patients. Thus, these results highlight that 14-3-3σ is an important regulator of tumour metabolism, and loss of 14-3-3σ expression is critical for cancer metabolic reprogramming. We anticipate that pharmacologically elevating the function of 14-3-3σ in tumours could be a promising direction for targeted anti-cancer metabolism therapy development in future.

Metabolic competition in the tumor microenvironment determines cancer progression (TUM7P.1016)

Abstract T cells produce cytokines that are critical for tumor immunity. However, during cancer, T cells often experience a decline in function preventing tumor regression. Why T cell hyporesponsiveness develops is unclear, but it is thought to result from lack of dominant epitope-specificity, continuous antigen exposure, and suppression by other immune cells. Previously we have shown that T cells need to engage aerobic glycolysis to optimally produce IFN-γ. Using a well-characterized mouse sarcoma model we show here that tumor mediated glucose consumption metabolically restricts tumor-infiltrating T cells (TILs), which dampens their mTOR activity, decreases their glycolytic capacity and therefore, limits their IFN-γ production, leading to tumor progression. We show that anti-CTLA-4, anti-PD-1, or anti-PD-L1 blockade therapy, which induces regression of progressing sarcomas, restores glucose in the tumor microenvironment and rescues glycolysis in TILs. Moreover, we demonstrate that blocking PD-L1 directly on tumor cells dampens tumor glycolysis and glucose uptake. Finally, we show that an antigenic sarcoma that normally is rejected can turn into a progressing tumor when its glycolytic rate is enhanced. Our data show that metabolic competition in the tumor microenvironment dictates T cell function and that this influences cancer progression. Combining therapies that blunt tumor cell metabolism with those that promote glycolysis in TILs could provide new effective treatments for cancer.

Non-invasive, simultaneous quantification of vascular oxygenation and glucose uptake in tissue.

We report the development of non-invasive, fiber-based diffuse optical spectroscopy for simultaneously quantifying vascular oxygenation (SO2) and glucose uptake in solid tumors in vivo. Glucose uptake was measured using a fluorescent glucose analog, 2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl)amino]-2-deoxyglucose (2-NBDG). Quantification of label-free SO2 and 2-NBDG-fluorescence-based glucose uptake 60 minutes after administration of the tracer (2-NBDG60) was performed using computational models of light-tissue interaction. This study was carried out on normal tissue and 4T1 and 4T07 murine mammary tumor xenografts in vivo. Injection of 2-NBDG did not cause a significant change in optical measurements of SO2, demonstrating its suitability as a functional reporter of tumor glucose uptake. Correction of measured 2-NBDG-fluorescence for the effects of absorption and scattering significantly improved contrast between tumor and normal tissue. The 4T1 and 4T07 tumors showed significantly decreased SO2, and 4T1 tumors demonstrated increased 2-NBDG60 compared with normal tissue (60 minutes after the administration of 2-NBDG when perfusion-mediated effects have cleared). 2-NBDG-fluorescence was found to be highly sensitive to food deprivation-induced reduction in blood glucose levels, demonstrating that this endpoint is indeed sensitive to glycolytic demand. 2-NBDG60 was also found to be linearly related to dose, underscoring the importance of calibrating for dose when comparing across animals or experiments. 4T1 tumors demonstrated an inverse relationship between 2-NBDG60 and SO2 that was consistent with the Pasteur effect, particularly when exposed to hypoxic gas breathing. Our results illustrate the potential of optical spectroscopy to provide valuable information about the metabolic status of tumors, with important implications for cancer prognosis.

Abstract 4690: A multimodality imaging end-point study of everolimus and ganetespib in treatment of pancreatic cancer: A pre-clinical PET/MRI/MRS study

Abstract Background: mTOR is a significant regulator of cell metabolism, proliferation, autophagy, and is strongly linked to cancer cell survival. This suggests that inhibiting mTOR with everolimus (RAD001) may inhibit tumor cell growth while promoting cell death. The aim was to establish imaging end-points for the efficacy of everolimus in combination with the second generation HSP-90 inhibitor ganetespib in everolimus resistant pancreatic cancer (based on promising results from initial patient trials). This study aimed to establish metabolic (FDG-PET and MRS), morphological (DWI), and anatomical (magnetic resonance imaging, MRI) end-points for mTOR and HSP inhibitor response in mouse pancreatic adenocarcinoma xenografts. Methods: Human Panc-159 tumor xenografts were established in athymic nude mice. Everolimus was administered orally at a daily dose of 5 mg/kg; ganetespib was administered via tail vein injection weekly 100 mg/kg. PET/DWI-MRI imaging was done at baseline, mid-study (Day 8-9), and end of study (Day 21-22). At end of study, mice were sacrificed, and tumors were extracted with perchloric acid for use in 1H-MRS metabolomics. Multivariate analysis was conducted with MetaboAnylast2.0 software. Results: Single treatments showed no significant inhibition of tumor growth or decrease in tumor cellularity. Everolimus single treatment did cause a slight decrease (p = 0.0296 by FDG-PET) in glucose uptake- as previously reported for the mTOR pathway inhibition, while ganetespib alone did not alter glucose uptake. Combination treatment inhibited tumor growth (p= 0.0018 by MRI) in addition to decreasing tumor cellularity (p = 0.0323 by DWI). Combination treatment also decreased tumor metabolic activity as demonstrated through the decrease in glucose uptake (p = 0.0085). Multivariate analysis on combined quantitative metabolic and imaging data sets (including tumor volume, FDG-SUV, cellularity, and 1H-MRS derived concentrations of endogenous metabolites) showed group separation between the control and combination treatment groups. Variables with highest importance in projection (VIP) accounting for group separation were tumor cellularity (VIP = 3.0262), tumor volume (VIP =2.3178), phospholipid-associated glycerol (VIP = 1.9073), and FDG-SUV (VIP = 1.3406). Conclusions: Our study provides the rational of combining everolimus with ganetespib to overcome drug resistance and increase treatment responsiveness in pancreatic cancer. Combination treatment did result in decreased tumor growth, cellularity, phospholipid metabolism and glucose uptake giving potential for these variables to serve as effective biomarkers for therapeutic response once validated in clinical trials. Even though Panc-159 is highly resistant to single everolimus treatment, this combination treatment with an HSP-90 inhibitor provides first evidence of proliferation and metabolic response. Citation Format: Justin Y. Lee, Lora A. Wilson, Jerry Choi, Kendra M. Huber, Andrea L. Merz, Colin D. Weekes, Natalie J. Serkova. A multimodality imaging end-point study of everolimus and ganetespib in treatment of pancreatic cancer: A pre-clinical PET/MRI/MRS study. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4690. doi:10.1158/1538-7445.AM2014-4690

Estradiol promotes pentose phosphate pathway addiction and cell survival via reactivation of Akt in mTORC1 hyperactive cells

Lymphangioleiomyomatosis (LAM) is a female-predominant interstitial lung disease that can lead to respiratory failure. LAM cells typically have inactivating TSC2 mutations, leading to mTORC1 activation. The gender specificity of LAM suggests that estradiol contributes to disease development, yet the underlying pathogenic mechanisms are not completely understood. Using metabolomic profiling, we identified an estradiol-enhanced pentose phosphate pathway signature in Tsc2-deficient cells. Estradiol increased levels of cellular NADPH, decreased levels of reactive oxygen species, and enhanced cell survival under oxidative stress. Mechanistically, estradiol reactivated Akt in TSC2-deficient cells in vitro and in vivo, induced membrane translocation of glucose transporters (GLUT1 or GLUT4), and increased glucose uptake in an Akt-dependent manner. 18F-FDG-PET imaging demonstrated enhanced glucose uptake in xenograft tumors of Tsc2-deficient cells from estradiol-treated mice. Expression array study identified estradiol-enhanced transcript levels of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the pentose phosphate pathway. Consistent with this, G6PD was abundant in xenograft tumors and lung metastatic lesions of Tsc2-deficient cells from estradiol-treated mice. Molecular depletion of G6PD attenuated estradiol-enhanced survival in vitro, and treatment with 6-aminonicotinamide, a competitive inhibitor of G6PD, reduced lung colonization of Tsc2-deficient cells. Collectively, these data indicate that estradiol promotes glucose metabolism in mTORC1 hyperactive cells through the pentose phosphate pathway via Akt reactivation and G6PD upregulation, thereby enhancing cell survival under oxidative stress. Interestingly, a strong correlation between estrogen exposure and G6PD was also found in breast cancer cells. Targeting the pentose phosphate pathway may have therapeutic benefit for LAM and possibly other hormonally dependent neoplasms.

Quantitative redox imaging biomarkers for studying tissue metabolic state and its heterogeneity.

NAD+/NADH redox state has been implicated in many diseases such as cancer and diabetes as well as in the regulation of embryonic development and aging. To fluorimetrically assess the mitochondrial redox state, Dr. Chance and co-workers measured the fluorescence of NADH and oxidized flavoproteins (Fp) including flavin-adenine-dinucleotide (FAD) and demonstrated their ratio (i.e. the redox ratio) is a sensitive indicator of the mitochondrial redox states. The Chance redox scanner was built to simultaneously measure NADH and Fp in tissue at submillimeter scale in 3D using the freeze-trap protocol. This paper summarizes our recent research experience, development and new applications of the redox scanning technique in collaboration with Dr.Chance beginning in 2005. Dr. Chance initiated or actively involved in many of the projects during the last several years of his life. We advanced the redox scanning technique by measuring the nominal concentrations (in reference to the frozen solution standards) of the endogenous fluorescent analytes, i.e., [NADH] and [Fp] to quantify the redox ratios in various biological tissues. The advancement has enabled us to identify an array of the redox indices as quantitative imaging biomarkers (including [NADH], [Fp], [Fp]/([NADH] + [Fp]), [NADH]/[Fp], and their standard deviations) for studying some important biological questions on cancer and normal tissue metabolism. We found that the redox indices were associated or changed with (1) tumorigenesis (cancer versus non-cancer of human breast tissue biopsies); (2) tumor metastatic potential; (3) tumor glucose uptake; (4) tumor p53 status; (5) PI3K pathway activation in premalignant tissue; (6) therapeutic effects on tumors; (7) embryonic stem cell differentiation; (8) the heart under fasting. Together, our work demonstrated that the tissue redox indices obtained from the redox scanning technique may provide useful information about tissue metabolism and physiology status in normal and diseased tissues. The Chance redox scanner and other redox imaging techniques may have wide-ranging potential applications in many fields, such as cancer, diabetes, developmental process, mitochondrial diseases, neurodegenerative diseases, and aging.

Glucose promotes breast cancer aggression and reduces metformin efficacy

Metformin treatment has been associated with a decrease in breast cancer risk and improved survival. Metformin induces complex cellular changes, resulting in decreased tumor cell proliferation, reduction of stem cells, and apoptosis. Using a carcinogen-induced rodent model of mammary tumorigenesis, we recently demonstrated that overfeeding in obese animals is associated with a 50% increase in tumor glucose uptake, increased proliferation, and tumor cell reprogramming to an “aggressive” metabolic state. Metformin significantly inhibited these pro-tumorigenic effects. We hypothesized that a dynamic relationship exists between chronic energy excess (glucose by dose) and metformin efficacy/action. Media glucose concentrations above 5 mmol/L was associated with significant increase in breast cancer cell proliferation, clonogenicity, motility, upregulation/activation of pro-oncogenic signaling, and reduction in apoptosis. These effects were most significant in triple-negative breast cancer (TNBC) cell lines. High-glucose conditions (10 mmol/L or above) significantly abrogated the effects of metformin. Mechanisms of metformin action at normal vs. high glucose overlapped but were not identical; for example, metformin reduced IGF-1R expression in both the HER2+ SK-BR-3 and TNBC MDA-MB-468 cell lines more significantly at 5, as compared with 10 mmol/L glucose. Significant changes in gene profiles related to apoptosis, cellular processes, metabolic processes, and cell proliferation occurred with metformin treatment in cells grown at 5 mmol/L glucose, whereas under high-glucose conditions, metformin did not significantly increase apoptotic/cellular death genes. These data indicate that failure to maintain glucose homeostasis may promote a more aggressive breast cancer phenotype and alter metformin efficacy and mechanisms of action.

Bisected, complex N-glycans and galectins in mouse mammary tumor progression and human breast cancer

Bisected, complex N-glycans on glycoproteins are generated by the glycosyltransferase MGAT3 and cause reduced cell surface binding of galectins. Previously, we showed that MGAT3 reduces growth factor signaling and retards mammary tumor progression driven by the Polyoma middle T antigen (PyMT) expressed in mammary epithelium under the mouse mammary tumor virus (MMTV) promoter. However, the penetrance of the tumor phenotype became variable in mixed FVB/N and C57BL/6 female mice and we therefore investigated a congenic C57BL/6 Mgat3(-/-)/MMTV-PyMT model. In the absence of MGAT3, C57BL/6 Mgat3(-/-)/MMTV-PyMT females exhibited accelerated tumor appearance and increased tumor burden, glucose uptake in tumors and lung metastasis. Nevertheless, activation of extracellular signal-regulated kinase (ERK)1/2 or protein kinase B (AKT) was reduced in ∼20-week C57BL/6 MMTV-PyMT tumors lacking MGAT3. Activation of focal adhesion kinase (FAK), protein tyrosine kinase Src, and p38 mitogen-activated protein kinase were similar to that of controls. All the eight mouse galectin genes were expressed in mammary tumors and tumor epithelial cells (TECs), but galectin-2 and -12 were not detected by western analysis in tumors, and galectin-7 was not detected in 60% of the TEC lines. From microarray data reported for human breast cancers, at least 10 galectin and 7 N-glycan N-acetylglucosaminyl (GlcNAc)-transferase (MGAT) genes are expressed in tumor tissue, and expression often varies significantly between different breast cancer subtypes. Thus, in summary, while MGAT3 and bisected complex N-glycans retard mouse mammary tumor progression, genetic background may modify this effect; identification of key galectins that promote mammary tumor progression in mice is not straightforward because all the eight galectin genes are expressed; and high levels of MGAT3, galectin-4, -8, -10, -13 and -14 transcripts correlate with better relapse-free survival in human breast cancer.

Translating Imaging Results into Tumor Biology: FDG-PET and The Response to Chemoradiation in Human Cervical Carcinoma

(18)F-fluoro-deoxyglucose-positron emission tomography (FDG-PET) is a molecular imaging technique that can be used to monitor treatment-related changes in tumor glucose uptake. In cervical cancer, the FDG-PET response is predictive of survival outcome after chemoradiation. In an effort to understand the signaling pathways that regulate the FDG-PET response in cervical cancer, gene expression profiling was performed. Gene set enrichment analysis (GSEA) identified alterations in expression of genes from the PI3K/AKT signaling pathway in tumors with incomplete FDG-PET response after chemoradiation. Pretreatment phosphorylation and activation of AKT is common in cervical cancer, and patients whose tumors have increased pAKT expression prior to treatment have inferior survival outcomes after standard chemoradiation. Recently, activating mutations in the PIK3CA gene have been identified that are associated with poor prognosis after chemoradiation in cervical cancer. These results suggest that targeted inhibition of PI3K/AKT may improve response to chemoradiation in cervical cancer.

In vivo imaging of glucose uptake and metabolism in tumors

Tumors display a greater reliance on glycolysis for energy production than normal tissues. We have developed a non-invasive method for imaging glucose uptake in vivo, which is based on magnetic resonance imaging, and allows the uptake of non-labeled glucose to be measured via the chemical exchange of protons between hydroxyl groups and water. This method differs from existing molecular imaging methods, as it permits detection of the delivery and uptake of a metabolically active compound at physiological quantities. We show that our technique, named glucose chemical exchange saturation transfer (glucoCEST), is sensitive to tumor glucose accumulation in colorectal tumor models, and can distinguish tumor types with differing metabolic characteristics and pathophysiology. The results of this study suggest that glucoCEST has potential as a useful and cost-effective method for characterizing disease and assessing response to therapy in the clinic.

Changes in the tumor glucose-uptake measured by 18F-FDG PET with two weeks of single-agent cetuximab in localized squamous cell carcinoma of the esophagus.

e15042 Background: Cetuximab (CET), an antibody directed against epidermal growth factor receptor (EGFR) has proved efficacy in squamous cell cancer (SCC) of the head and neck in vitro and in vivo by enhancing the activity of chemo- and radiotherapy. The aim was to investigate the early metabolic response in esophageal SCC induced by single agent CET. Methods: Patients with cT3 Nx esophageal SCC received single agent CET for two weeks (400mg/m2 i. v. d -15 followed by 250mg/m2 d -8) before entering a neoadjuvant dose escalation protocol of weekly cetuximab plus weekly oxaliplatin (starting dose level 45mg/m²; d1,8,15,22,29), plus 5-FU cont. i.v. (starting dose level 180mg/m²/d; d1-5, 8-12, 15-19, 22-26, 29-33) and radiotherapy (45Gy cumulative dose; 1.8Gy/d). Surgery was scheduled 4-6 weeks after chemoradiation (CRT). Tumor FDG uptake was assessed by PET at baseline, two weeks after start of CET and two weeks after start of CRT. Standard uptake values (SUV) of the two response PETs were compared with SUVs measured at baseline and correlated with the histopathological response data. Results: 11 patients are assessable for metabolic and histopathological response. Decreases in the SUVs two weeks after the start of CET compared with baseline SUV ranged from -16% to -70% (median -24%) and from 0% to -72% (median -39%) two weeks after start of CRT. Three patients were classified as complete histopathological responders. One patient had a subtotal (<10% residual tumor) and three patients a moderate response (10-50% residual tumor). No histopathological response was seen in 4 patients. We found an association between FDG uptake decreases both after single agent CET and after two weeks of CRT and a favourable histopathological response with no statistical significance due to the low number of cases. Conclusions: This study shows that single agent CET can lead to a marked and early decrease in tumor glucose uptake. Our findings suggest that there may be an association between the early decrease in FDG uptake during CET monotherapy, indicating a growth dependency of some tumors from the EGFR signal pathway. These preliminary observations require confirmation in a larger patient cohort. Clinical trial information: 2006-001097-24.

Intermittent and continuous imatinib in a human GIST xenograft model carrying KIT exon 17 resistance mutation D816H

Background. Acquired resistance to imatinib is frequently caused by secondary KIT mutations. We have investigated the effects of imatinib in mice with human gastrointestinal stromal tumour (GIST) xenograft which harbours a primary exon 11 deletion mutation and a secondary imatinib resistance mutation D816H in exon 17. Such mutations are commonly present in imatinib-resistant GIST in humans. Material and methods. The mice were randomly allocated to receive imatinib either continuously or intermittently. Dynamic 18F-FDG PET was performed and blood volume fraction (vB), rate transfer constants (k1, k2, k3) and metabolic rate of 18F-FDG (MRFDG) were computed using a three-compartment model. Tumours were evaluated for the mitotic rate and the expression of HIF-1α , caspase-3 and glucose transporters (GLUTs). Results. Both intermittent and continuous imatinib delayed tumour growth significantly compared to controls, significantly in favour of the latter. k1 (representing perfusion, vascular permeability and binding of 18F-FDG to the GLUTs) was significantly higher in the intermittent group compared to the continuous group, as was tumour GLUT-3 expression. k3 (representing internalisation of 18F-FDG to the cells) and MRFDG were significantly lower. Conclusion. Imatinib delays GIST xenograft growth despite the presence of the D816H resistance mutation. The schedule of imatinib administration may influence tumour glucose uptake rate and metabolic rate.

Metformin—an Adjunct Antineoplastic Therapy—Divergently Modulates Tumor Metabolism and Proliferation, Interfering with Early Response Prediction by 18F-FDG PET Imaging

Over the last several years, epidemiologic data have suggested that the antidiabetes drug metformin (MET), an adenosine monophosphate-activated protein kinase (AMPK) activator, improves progression-free survival of patients with multiple cancers; more than 30 clinical trials are under way to confirm this finding. We postulated that the role of AMPK as a central cellular energy sensor would result in opposite effects on glucose uptake and proliferation, suggesting different roles for (18)F-FDG and 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) in assessing its effectiveness as an antineoplastic agent. Colon cancer cell lines HT29 (human) and MC26 (murine) were treated for 24 or 72 h with a range of MET concentrations (0-10 mM). Western blotting was used to study the activation of AMPK after MET treatment. Glucose uptake and cell proliferation were measured by cell retention studies with either (18)F-FDG or (18)F-FLT. EdU (ethynyl deoxyuridine, a thymidine analog) and annexin-propidium iodide flow cytometry was performed to determine cell cycle S-phase and apoptotic changes. In vivo (18)F-FDG and (18)F-FLT PET images were acquired before and 24 h after MET treatment of HT29 tumor-bearing mice. After 24 h of MET incubation, phosphorylated AMPK levels increased severalfold in both cell lines, whereas total AMPK levels remained unchanged. In cell retention studies, (18)F-FDG uptake increased but (18)F-FLT retention decreased significantly in both cell lines. The numbers of HT29 and MC26 cells in the S phase decreased 36% and 33%, respectively, after MET therapy. Apoptosis increased 10.5-fold and 5.8-fold in HT29 and MC26 cells, respectively, after 72 h of incubation with MET. PET imaging revealed increased (18)F-FDG uptake (mean ± SEM standardized uptake values were 0.71 ± 0.03 before and 1.29 ± 0.11 after MET therapy) (P < 0.05) and decreased (18)F-FLT uptake (mean ± SEM standardized uptake values were 1.18 ± 0.05 before and 0.89 ± 0.01 after MET therapy) (P < 0.05) in HT29 tumor-bearing mice. MET, through activation of the AMPK pathway, produces a dose-dependent increase in tumor glucose uptake while decreasing cell proliferation in human and murine colon cancer cells. Thus, changes in (18)F-FDG uptake after MET treatment may be misleading. (18)F-FLT imaging is a promising alternative that correlates with the tumor response.

Abstract 5167: Melatonin inhibition of linoleic acid transport and 13-HODE production in HeLa human cervical adenocarcinoma occurs via receptor-mediated signal transduction

Abstract Over 12,000 women in the U.S. alone this year will be diagnosed with cervical cancer, ranking third behind endometrial and ovarian cancers. Patients with an advanced stage cervical cancer have only a 15-20% survival rate at 5 years. Observational studies of the night-shift worker population have shown an increased incidence of risk in persons exposed to ocular light at night in a number of cancers, including cervical cancer. This finding was associated with an inhibition of nighttime pineal gland production of melatonin, the circadian neurohormone shown to suppress tumor metabolic and proliferative activity. This occurs via melatonin inhibition of tumor linoleic acid (LA) uptake and conversion to 13-hydroxyoctadecadienoic acid (13-HODE), a molecule that upregulates epidermal growth factor and insulin-like growth factor-I-induced mitogenesis. Here, we investigate the effects in vivo of melatonin (500 pM) on perfused, tissue-isolated HeLa human adenocarcinoma xenografts in nude rats. HeLa adenocarcinoma latency-to-onset and tumor growth rates were, respectively, 8 days and 0.09 ± 0.01 g/day; mean tumor weights were 5.9 ± 0.3 g (n = 32). Cervical adenocarcinomas perfused in situ with donor rodent blood for 150 minutes (Controls) revealed a tumor glucose uptake and lactate release of 11.4 ± 0.9 ng/min/g and −20.4 ± 2.2 nmol/min/g, respectively; control tumor LA uptake and 13-HODE release was 0.71 ± 0.08 μg/min/g and 0.35 ± 0.07 ng/min/g, respectively. Incorporation of 3H-thymidine into tumor DNA and DNA content, respectively, were 21.2 ± 0.6 dpms/μg DNA and 2.5 ± 0.1 mg/g tumor. Adenocarcinomas perfused with arterial donor blood augmented with physiological nocturnal levels of 500 pM melatonin showed over a 20% abrogation of tumor glucose uptake and lactate production, O2 consumption and CO2 production, and a complete inhibition of LA uptake, 13-HODE release, ERK 1/2, MEK, Akt, GSK3β proliferative activities, and over an 85% reduction in tumor cAMP levels and 3H-thymidine incorporation into tumor DNA. Supplementation with the non-selective MT1/MT2 melatonin antagonist S20928, forskolin, 8-Bromo-cyclic-AMP, or pertusiss toxin completely reversed the tumor growth inhibitory response. Also, addition of 13-HODE reversed 3H-thymidine into tumor DNA, but had no effect on LA uptake. The preliminary results presented here demonstrate, for the first time, that nocturnal melatonin levels suppress HeLa cervical adenocarcinoma metabolism and proliferation in vivo via a melatonin receptor mediated signal transduction mechanism. A better understanding of this signaling pathway and the regulation of LA in cancer metabolism and proliferation may lead to new therapeutic and/or chemopreventative interventions. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5167. doi:1538-7445.AM2012-5167

Prognostic significance of SUV on PET/CT in patients with localised oesophagogastric junction cancer receiving neoadjuvant chemotherapy/chemoradiation: a systematic review and meta-analysis

The objective of this study was to comprehensively review the evidence for use of pre-treatment, post-treatment and changes in tumour glucose uptake that were assessed by 18-fludeoxyglucose ((18)F-FDG) positron emission tomography (PET) early, during or immediately after neoadjuvant chemotherapy/chemoradiation to predict prognosis of localised oesophagogastric junction (AEG) cancer. We searched for articles published in English; limited to AEG; (18)F-FDG uptake on PET performed on a dedicated device; dealt with the impact of standard uptake value (SUV) on survival. We extracted an estimate of the log hazard ratios (HRs) and their variances and performed meta-analysis. 798 patients with AEG were included. And the scan time for (18)F-FDG-PET was as follows: prior to therapy (PET1, n=646), exactly 2 weeks after initiation of neoadjuvant therapy (PET2, n=245), and pre-operatively (PET3, n=278). In the two meta-analyses for overall survival, including the studies that dealt with reduction of tumour maximum SUV (SUV(max)) (from PET1 to PET2/PET3 and from PET1 to PET2), the results were similar, with the overall HR for non-responders being 1.83 [95% confidence interval (CI), 1.41-2.36] and 2.62 (95% CI, 1.61-4.26), respectively; as for disease-free survival, the combined HR was 2.92 (95% CI, 2.08-4.10) and 2.39 (95% CI, 1.57-3.64), respectively. The meta-analyses did not attribute significant prognostic values to SUV(max) before and during therapy in localised AEG. Relative changes in FDG-uptake of AEG are better prognosticators. Early metabolic changes from PET1 to PET2 may provide the same accuracy for prediction of treatment outcome as late changes from PET1 to PET3.

Quantitation of glucose uptake in tumors by dynamic FDG-PET has less glucose bias and lower variability when adjusted for partial saturation of glucose transport

BackgroundA retrospective analysis of estimates of tumor glucose uptake from 1,192 dynamic 2-deoxy-2-(18F)fluoro-D-glucose-positron-emission tomography [FDG-PET] scans showed strong correlations between blood glucose and both the uptake rate constant [Ki] and the metabolic rate of glucose [MRGluc], hindering the interpretation of PET scans acquired under conditions of altered blood glucose. We sought a method to reduce this glucose bias without increasing the between-subject or test-retest variability and did this by considering that tissue glucose transport is a saturable yet unsaturated process best described as a nonlinear function of glucose levels.MethodsPatlak-Gjedde analysis was used to compute Ki from 30-min dynamic PET scans in tumor-bearing mice. MRGluc was calculated by factoring in the blood glucose level and a lumped constant equal to unity. Alternatively, we assumed that glucose consumption is saturable according to Michaelis-Menten kinetics and estimated a hypothetical maximum rate of glucose consumption [MRGlucMAX] by multiplying Ki and (KM + [glucose]), where KM is a half-saturation Michaelis constant for glucose uptake. Results were computed for 112 separate studies of 8 to 12 scans each; test-retest statistics were measured in a suitable subset of 201 mice.ResultsA KM value of 130 mg/dL was determined from the data based on minimizing the average correlation between blood glucose and the uptake metric. Using MRGlucMAX resulted in the following benefits compared to using MRGluc: (1) the median correlation with blood glucose was practically zero, and yet (2) the test-retest coefficient of variation [COV] was reduced by 13.4%, and (3) the between-animal COVs were reduced by15.5%. In statistically equivalent terms, achieving the same reduction in between-animal COV while using the traditional MRGluc would require a 40% increase in sample size.ConclusionsMRGluc appeared to overcorrect tumor FDG data for changing glucose levels. Applying partial saturation correction using MRGlucMAX offered reduced bias, reduced variability, and potentially increased statistical power. We recommend further investigation of MRGlucMAX in quantitative studies of tumor FDG uptake.

The power of FDG-PET to detect treatment effects is increased by glucose correction using a Michaelis constant.

BackgroundWe recently showed improved between-subject variability in our [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) experiments using a Michaelis-Menten transport model to calculate the metabolic tumor glucose uptake rate extrapolated to the hypothetical condition of glucose saturation: , where Ki is the image-derived FDG uptake rate constant, KM is the half-saturation Michaelis constant, and [glc] is the blood glucose concentration. Compared to measurements of Ki alone, or calculations of the scan-time metabolic glucose uptake rate (MRgluc = Ki * [glc]) or the glucose-normalized uptake rate (MRgluc = Ki*[glc]/(100 mg/dL), we suggested that could offer increased statistical power in treatment studies; here, we confirm this in theory and practice.MethodsWe compared Ki, MRgluc (both with and without glucose normalization), and as FDG-PET measures of treatment-induced changes in tumor glucose uptake independent of any systemic changes in blood glucose caused either by natural variation or by side effects of drug action. Data from three xenograft models with independent evidence of altered tumor cell glucose uptake were studied and generalized with statistical simulations and mathematical derivations. To obtain representative simulation parameters, we studied the distributions of Ki from FDG-PET scans and blood [glucose] values in 66 cohorts of mice (665 individual mice). Treatment effects were simulated by varying and back-calculating the mean Ki under the Michaelis-Menten model with KM = 130 mg/dL. This was repeated to represent cases of low, average, and high variability in Ki (at a given glucose level) observed among the 66 PET cohorts.ResultsThere was excellent agreement between derivations, simulations, and experiments. Even modestly different (20%) blood glucose levels caused Ki and especially MRgluc to become unreliable through false positive results while remained unbiased. The greatest benefit occurred when Ki measurements (at a given glucose level) had low variability. Even when the power benefit was negligible, the use of carried no statistical penalty. Congruent with theory and simulations, showed in our experiments an average 21% statistical power improvement with respect to MRgluc and 10% with respect to Ki (approximately 20% savings in sample size). The results were robust in the face of imprecise blood glucose measurements and KM values.ConclusionsWhen evaluating the direct effects of treatment on tumor tissue with FDG-PET, employing a Michaelis-Menten glucose correction factor gives the most statistically powerful results. The well-known alternative ‘correction’, multiplying Ki by blood glucose (or normalized blood glucose), appears to be counter-productive in this setting and should be avoided.

Metformin abolishes increased tumor 18F-2-fluoro-2-deoxy-D-glucose uptake associated with a high energy diet

Insulin regulates glucose uptake by normal tissues. Although there is evidence that certain cancers are growth-stimulated by insulin, the possibility that insulin influences tumor glucose uptake as assessed by 18F-2-Fluoro-2-Deoxy-d-Glucose Positron Emission Tomography (FDG-PET) has not been studied in detail. We present a model of diet-induced hyperinsulinemia associated with increased insulin receptor activation in neoplastic tissue and with increased tumor FDG-PET image intensity. Metformin abolished the diet-induced increases in serum insulin level, tumor insulin receptor activation and tumor FDG uptake associated with the high energy diet but had no effect on these measurements in mice on a control diet. These findings provide the first functional imaging correlate of the well-known adverse effect of caloric excess on cancer outcome. They demonstrate that, for a subset of neoplasms, diet and insulin are variables that affect tumor FDG uptake and have implications for design of clinical trials of metformin as an antineoplastic agent.

18F-FDG PET–Guided Salvage Neoadjuvant Radiochemotherapy of Adenocarcinoma of the Esophagogastric Junction: The MUNICON II Trial

Previous studies demonstrated that chemotherapy-induced changes in tumor glucose metabolism measured with (18)F-FDG PET identify patients who benefit from preoperative chemotherapy and those who do not. The prognosis for chemotherapy metabolic nonresponders is poorer than for metabolic responders. Therefore, we initiated this prospective trial to improve the clinical outcome of metabolic nonresponders using a salvage neoadjuvant radiochemotherapy. Fifty-six patients with locally advanced adenocarcinomas of the esophagogastric junction were included. Tumor glucose uptake was assessed by (18)F-FDG PET before chemotherapy and 14 d after initiation of chemotherapy. PET nonresponders received salvage neoadjuvant radiochemotherapy, whereas metabolic responders received neoadjuvant chemotherapy for 3 mo before surgery. Thirty-three patients were metabolic responders, and 23 were nonresponders. Resection was performed on 54 patients. R0 resection rate was 82% (95% confidence interval [CI], 66%-91%) in metabolic responders and 70% (95% CI, 49%-84%) in metabolic nonresponders (P = 0.51). Major histologic remissions were observed in 12 metabolic responders (36%; 95% CI, 22%-53%) and 6 nonresponders (26%; 95% CI, 13%-46%). One-year progression-free rate was 74% ± 8% in PET responders and 57% ± 10% in metabolic nonresponders (log rank test, P = 0.035). One-year overall survival was comparable between the groups (∼80%), and 2-y overall survival was estimated to be 71% ± 8% in metabolic responders and 42% ± 11% in PET nonresponders (hazard ratio, 1.9; 95% CI, 0.87-4.24; P = 0.10). This prospective study showed the feasibility of a PET-guided treatment algorithm. However, by comparing the groups of nonresponding patients in the current trial and the previous published MUNICON (Metabolic response evalUatioN for Individualisation of neoadjuvant Chemotherapy in Esophageal and esophagogastric adeNocarcinoma) I trial, increased histopathologic response was observed after salvage radiochemotherapy, but the primary endpoint of the study to increase the R0 resection rate was not met. The prognosis of the subgroup of PET nonresponders remains poor, indicating their different tumor biology.

FDG-PET as a predictive marker for therapy with everolimus in metastatic renal cell cancer (mRCC).

e15047 Background: The oral mTOR inhibitor, everolimus, affects tumor growth by targeting cellular metabolic proliferation pathways and delays RCC progression. Yet most patients (pts) will not respond. Preclinical evidence suggests that elevated tumor glucose uptake as quantified by FDG-PET may predict anti-tumor activity. Methods: In this multicenter study, mRCC pts refractory to VEGF inhibition were treated with standard dose everolimus. FDG-PET scans were obtained at baseline and at 1 month; serial CT scans were obtained at baseline and every 8 weeks. Maximum standardized uptake value (SUVmax) of the most FDG avid lesion, the average SUVmax of all measured lesions and the corresponding one-month relative change were examined for association with 8-week change in tumor size. 60 pts were planned to provide 81% power (α=0.1) to detect a difference between a mean 20% vs. 10% increase in RECIST based tumor burden measurement in pts with low (SUVmax≤4) vs. high (SUVmax>4) FDG uptake. Results: 63 pts were enrolled; 51 were evaluable for primary endpoint of which 48 had both PET scans. Pt characteristics included: 46 (73%) clear cell histology, median age 61 (32 – 80), median number of prior systemic therapies 1.5 (1 – 4). Median pre- and post-treatment average SUVmax were 7 (1 –17.9) and 4.2 (1 – 13.9), respectively. Median relative change in average SUVmax was -21.2% (-59.8% – 0%). RECIST-based measurements demonstrated an average change in tumor burden of 0.3% (-32.0% – 35.9%) at 8 weeks, with 2 patients (4%) experiencing a PR. Among SUV measures considered, relative change in average SUVmax was the best predictor of change in tumor burden (all evaluable p=0.013; clear cell subtype p=0.031), but the overall correlation was modest (ρ = 0.36). Baseline SUV characteristics and low vs. high SUV classification were not associated with tumor response. Evaluation of progression and overall survival is pending. Conclusions: Systemic therapy with everolimus substantially decreased SUVs on follow-up PET scans in mRCC pts, but these changes were only modestly correlated with changes in tumor size. Correlation with survival metrics will be assessed. Clinical use of FDG-PET based biomarkers is challenged by high variability.