Linked Hexokinase and Glucose-6-Phosphatase Activities Reflect Grade of Ovarian Malignancy

EANM guideline on the role of 2-[18F]FDG PET/CT in diagnosis, staging, prognostic value, therapy assessment and restaging of ovarian cancer, endorsed by the American College of Nuclear Medicine (ACNM), the Society of Nuclear Medicine and Molecular Imaging (SNMMI) and the International Atomic Energy Agency (IAEA)

In most patients with ovarian carcinoma, the diagnosis is reached when the disease is long past the initial stages, presenting already an advanced stage, and they usually have a very bad prognosis. Cytoreductive or debulking surgical procedures, platinum-based chemotherapy and targeted agents are key therapeutic elements. However, around 7 out of 10 patients present recurrent disease within 36 months from the initial diagnosis. The metastatic spread in ovarian cancer follows three pathways: contiguous dissemination across the peritoneum, dissemination through the lymphatic drainage and, although less importantly in this case, through the bloodstream. Radiological imaging, including ultrasound, CT and MRI, are the main imaging techniques in which management decisions are supported, CT being considered the best available technique for presurgical evaluation and staging purposes. Regarding 2-[¹⁸F]FDG PET/CT, the evidence available in the literature demonstrates efficacy in primary detection, disease staging and establishing the prognosis and especially for relapse detection. There is limited evidence when considering the evaluation of therapeutic response. This guideline summarizes the level of evidence and grade of recommendation for the clinical indications of 2-[¹⁸F]FDG PET/CT in each disease stage of ovarian carcinoma.

Toxicity and metabolism of 3-bromopyruvate in Caenorhabditis elegans

In this study, we aimed to evaluate the toxic effects, changes in life span, and expression of various metabolism-related genes in Caenorhabditis elegans, using RNA interference (RNAi) and mutant strains, after 3-bromopyruvate (3-BrPA) treatment. C. elegans was treated with various concentrations of 3-BrPA on nematode growth medium (NGM) plates, and their survival was monitored every 24 h. The expression of genes related to metabolism was measured by the real-time fluorescent quantitative polymerase chain reaction (qPCR). Nematode survival in the presence of 3-BrPA was also studied after silencing three hexokinase (HK) genes. The average life span of C. elegans cultured on NGM with 3-BrPA was shortened to 5.7 d compared with 7.7 d in the control group. hxk-1, hxk-2, and hxk-3 were overexpressed after the treatment with 3-BrPA. After successfully interfering hxk-1, hxk-2, and hxk-3, the 50% lethal concentration (LC₅₀) of all mutant nematodes decreased with 3-BrPA treatment for 24 h compared with that of the control. All the cyp35 genes tested were overexpressed, except cyp-35B3. The induction of cyp-35A1 expression was most obvious. The LC₅₀ values of the mutant strains cyp-35A1, cyp-35A2, cyp-35A4, cyp-35B3, and cyp-35C1 were lower than that of the control. Thus, the toxicity of 3-BrPA is closely related to its effect on hexokinase metabolism in nematodes, and the cyp-35 family plays a key role in the metabolism of 3-BrPA.

18F-Fluorodeoxyglucose Positron Emission Tomography Tracks the Heterogeneous Brain Susceptibility to the Hyperglycemia-Related Redox Stress

In cognitively normal patients, mild hyperglycemia selectively decreases 18F-Fluorodeoxyglucose (FDG) uptake in the posterior brain, reproducing Alzheimer disease pattern, hampering the diagnostic accuracy of this widely used tool. This phenomenon might involve either a heterogeneous response of glucose metabolism or a different sensitivity to hyperglycemia-related redox stress. Indeed, previous studies reported a close link between FDG uptake and activation of a specific pentose phosphate pathway (PPP), triggered by hexose-6P-dehydrogenase (H6PD) and contributing to fuel NADPH-dependent antioxidant responses in the endoplasmic reticulum (ER). To clarify this issue, dynamic positron emission tomography was performed in 40 BALB/c mice four weeks after administration of saline (n = 17) or 150 mg/kg streptozotocin (n = 23, STZ). Imaging data were compared with biochemical and histological indexes of glucose metabolism and redox balance. Cortical FDG uptake was homogeneous in controls, while it was selectively decreased in the posterior brain of STZ mice. This difference was independent of the activity of enzymes regulating glycolysis and cytosolic PPP, while it was paralleled by a decreased H6PD catalytic function and enhanced indexes of oxidative damage. Thus, the relative decrease in FDG uptake of the posterior brain reflects a lower activation of ER-PPP in response to hyperglycemia-related redox stress in these areas.