[18F]FDG and [11C]PK11195 PET imaging in the evaluation of brown adipose tissue - effects of cold and pharmacological stimuli and their association with crotamine intake in a male mouse model.

This study aimed to evaluate the role of positron emission tomography (PET) with [11C]PK11195 and [18F]FDG in the characterization of brown adipose tissue (BAT). METHODS: Male C57BL/6 mice were studied with the glucose analogue [18F]FDG (n = 21) and the TSPO mitochondrial tracer [11C]PK11195 (n = 28), without stimulus and after cold (6-9 °C) or beta-agonist (CL316243) stimuli. PET studies were performed at baseline and after 21 days of daily treatment with crotamine, which is a peptide described to induce adipocyte tissue browning and to increase BAT metabolism. Tracer uptake (SUVmax) was measured in the interscapular BAT and translocator protein 18 kDa (TSPO) expression was evaluated by immunohistochemistry. RESULTS: The cold stimulus increased [18F]FDG uptake compared to no-stimulus (5.21 ± 1.05 vs. 2.03 ± 0.21, p < 0.0001) and to beta-agonist stimulus (2.65 ± 0.39, p = 0.0003). After 21 days of treatment with crotamine, there was no significant difference in the [18F]FDG uptake compared to the baseline in the no-stimulus group and in the cold-stimulus group, with a significant increase in uptake after CL stimulus (baseline: 2.65 ± 0.39; 21 days crotamine: 4.77 ± 0.81, p = 0.0003). Evaluation of [11C]PK11195 at baseline shows that CL stimulus increases the BAT uptake compared to no-stimulus (4.47 ± 0.66 vs. 3.36 ± 0.68, p = 0.014). After 21 days of treatment with crotamine, there was no significant difference in the [11C]PK11195 uptake compared to the baseline in the no-stimulus group (2.94 ± 0.58, p = 0.7864) and also after CL stimulus (3.55 ± 0.79, p = 0.085). TSPO expression correlated with [11C]PK11195 uptake (r = 0.83, p = 0.018) but not with [18F]FDG uptake (r = 0.40, p = 0.516). CONCLUSIONS: [11C]PK11195 allowed the identification of BAT under thermoneutral conditions or after beta3-adrenergic stimulation in a direct correlation with TSPO expression. The beta-adrenergic stimulus, despite presenting a lower intensity of glycolytic activation compared to cold at baseline, allowed the observation of an increase in BAT uptake of [18F]FDG after 21 days of crotamine administration. Although some limitations were observed for the metabolic changes induced by crotamine, this study reinforced the potential of using [11C]PK11195 and/or [18F]FDG-PET to monitor the activation of BAT.

Locking and Unlocking Thrombin Function Using Immunoquiescent Nucleic Acid Nanoparticles with Regulated Retention In Vivo.

The unbalanced coagulation of blood is a life-threatening event that requires accurate and timely treatment. We introduce a user-friendly biomolecular platform based on modular RNA-DNA anticoagulant fibers programmed for reversible extracellular communication with thrombin and subsequent control of anticoagulation via a "kill-switch" mechanism that restores hemostasis. To demonstrate the potential of this reconfigurable technology, we designed and tested a set of anticoagulant fibers that carry different thrombin-binding aptamers. All fibers are immunoquiescent, as confirmed in freshly collected human peripheral blood mononuclear cells. To assess interindividual variability, the anticoagulation is confirmed in the blood of human donors from the U.S. and Brazil. The anticoagulant fibers reveal superior anticoagulant activity and prolonged renal clearance in vivo in comparison to free aptamers. Finally, we confirm the efficacy of the "kill-switch" mechanism in vivo in murine and porcine models.

Metformin-induced chemosensitization to cisplatin depends on P53 status and is inhibited by Jarid1b overexpression in non-small cell lung cancer cells.

Metformin has been tested as an anti-cancer therapy with potential to improve conventional chemotherapy. However, in some cases, metformin fails to sensitize tumors to chemotherapy. Here we test if the presence of P53 could predict the activity of metformin as an adjuvant for cisplatin-based therapy in non-small cell lung cancer (NSCLC). A549, HCC 827 (TP53 WT), H1299, and H358 (TP53 null) cell lines were used in this study. A549 cells were pre-treated with a sub-lethal dose of cisplatin to induce chemoresistance. The effects of metformin were tested both in vitro and in vivo and related to the ability of cells to accumulate Jarid1b, a histone demethylase involved in cisplatin resistance in different cancers. Metformin sensitized A549 and HCC 827 cells (but not H1299 and H358 cells) to cisplatin in a P53-dependent manner, changing its subcellular localization to the mitochondria. Treatment with a sub-lethal dose of cisplatin increased Jarid1b expression, yet downregulated P53 levels, protecting A549Res cells from metformin-induced chemosensitization to cisplatin and favored a glycolytic phenotype. Treatment with FL3, a synthetic flavagline, sensitized A549Res cells to cisplatin. In conclusion, metformin could potentially be used as an adjuvant for cisplatin-based therapy in NSCLC cells if wild type P53 is present.

99mTechnetium- or Cy7-Labeled Fab(Tocilizumab) as Potential Multiple Myeloma Imaging Agents.

BACKGROUND: Multiple Myeloma (MM) is a malignant hematologic disorder and the second most common blood cancer. Interleukin-6 (IL-6) has been identified as a crucial factor for the proliferation and survival of MM cells and the overexpression of IL-6 receptor is being studied as a molecular target for therapeutic and diagnostic use in myelomas and other comorbidities. Tocilizumab is a humanized monoclonal antibody that binds IL-6R. OBJECTIVE: We aim to label and evaluate Fab(Tocilizumab) with 99mTechnetium or Cy7 as potential MM imaging agents. METHODS: IL-6R distribution was analyzed by Laser Confocal Microscopy (LCM) in MM cell lines. Fab(Tocilizumab) was produced by the digestion of Tocilizumab with papain for 24h at 37°C, derivatized with NHS-HYNIC-Tfa and radiolabeled with 99mTc. Radiochemical stability and in vitro cell assays were evaluated. Biodistribution and SPECT/CT were performed. Also, Fab(Tocilizumab) was labeled with Cy7 for in vivo fluorescence imaging up to 72h. RESULTS: LCM analysis demonstrates IL-6R distribution on MM cell lines. Incubation with papain resulted in complete digestion of Tocilizumab and exhibited a good purity and homogeneity. Radiolabeling with 99mTc via NHS-HYNIC-Tfa was found to be fast, easy, reproducible and stable, revealing high radiochemical purity and without interfering with IL-6R recognition. Biodistribution and SPECT/CT studies showed a quick blood clearance and significant kidney and MM engrafted tumor uptake. Cy7-Fab(Tocilizumab) fluorescent imaging allowed MM1S tumor identification up to 72h p.i. CONCLUSION: These new molecular imaging agents could potentially be used in the clinical setting for staging and follow-up of MM through radioactive whole-body IL-6R expression visualization in vivo. The fluorescent version could be used for tissue sample evaluation and to guide surgical excision, if necessary.

Nanoradiopharmaceuticals for Bone Cancer Metastasis Imaging.

Drug delivery systems are under intense investigation all around the world, especially in oncology research. Indeed, in some cases, like bone metastasis, nanodrugs may represent the last and best choice for both treatment and imaging of early cancer foci. Nuclear medicine has been using MDP labelled with 99mTc as radiopharmaceuticals for many years; however, their use as nanoradiopharmaceuticals is very innovative and creates a new way to establish radiopharmacy in this new scenario offered by nanotechnology. In this study we developed and tested nano-MDP-labelled with 99mTc in rats induced with bone cancer metastasis and the results showed that it may work in patients. However, some further experiments are required in order to initiate protocols in humans.