scholarly journals Investigation of a Pharmacological Approach for Reduction of Renal Uptake of Radiolabeled ADAPT Scaffold Protein

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4448
Author(s):  
Anzhelika Vorobyeva ◽  
Maryam Oroujeni ◽  
Sarah Lindbo ◽  
Sophia Hober ◽  
Tianqi Xu ◽  
...  
Keyword(s):  
Growth Factor Receptor ◽  
Scaffold Proteins ◽  
High Dose ◽  
Radiolabeled Peptides ◽  
Renal Uptake ◽  
Recent Clinical Study ◽  
Clinical Strategies ◽  
Sodium Maleate ◽  
Epidermal Growth ◽  
Prolonged Retention

Albumin binding domain-Derived Affinity ProTeins (ADAPTs) are small (5 kDa) engineered scaffold proteins that are promising targeting agents for radionuclide-based imaging. A recent clinical study has demonstrated that radiolabeled ADAPTs can efficiently visualize human epidermal growth factor receptor 2 (HER2) expression in breast cancer using SPECT imaging. However, the use of ADAPTs directly labeled with radiometals for targeted radionuclide therapy is limited by their high reabsorption and prolonged retention of activity in kidneys. In this study, we investigated whether a co-injection of lysine or gelofusin, commonly used for reduction of renal uptake of radiolabeled peptides in clinics, would reduce the renal uptake of [99mTc]Tc(CO)3-ADAPT6 in NMRI mice. In order to better understand the mechanism behind the reabsorption of [99mTc]Tc(CO)3-ADAPT6, we included several compounds that act on various parts of the reabsorption system in kidneys. Administration of gelofusine, lysine, probenecid, furosemide, mannitol, or colchicine did not change the uptake of [99mTc]Tc(CO)3-ADAPT6 in kidneys. Sodium maleate reduced the uptake of [99mTc]Tc(CO)3-ADAPT6 to ca. 25% of the uptake in the control, a high dose of fructose (50 mmol/kg) reduced the uptake by ca. two-fold. However, a lower dose (20 mmol/kg) had no effect. These results indicate that common clinical strategies are not effective for reduction of kidney uptake of [99mTc]Tc(CO)3-ADAPT6 and that other strategies for reduction of activity uptake or retention in kidneys should be investigated for ADAPT6.

Radiolabeled Peptide Probes for Liver Cancer Imaging

2020 ◽  
Vol 27 (41) ◽  
pp. 6968-6986
Author(s):  
Rui Cao ◽  
Hongguang Liu ◽  
Zhen Cheng
Keyword(s):  
Liver Cancer ◽  
Cancer Diagnosis ◽  
Cancer Imaging ◽  
Growth Factor Receptor ◽  
Targeted Imaging ◽  
Cancer Death ◽  
Binding Properties ◽  
Radiolabeled Peptides ◽  
Epidermal Growth ◽  
Peptide Probes

Liver cancer/Hepatocellular Carcinoma (HCC) is a leading cause of cancer death and represents an important cause of mortality worldwide. Several biomarkers are overexpressed in liver cancer, such as Glypican 3 (GPC3) and Epidermal Growth Factor Receptor (EGFR). These biomarkers play important roles in the progression of tumors and could serve as imaging and therapeutic targets for this disease. Peptides with adequate stability, receptor binding properties, and biokinetic behavior have been intensively studied for liver cancer imaging. A great variety of them have been radiolabeled with clinically relevant radionuclides for liver cancer diagnosis, and many are promising imaging and therapeutic candidates for clinical translation. Herein, we summarize the advancement of radiolabeled peptides for the targeted imaging of liver cancer.

scholarly journals Ras Subcellular Localization Defines Extracellular Signal-Regulated Kinase 1 and 2 Substrate Specificity through Distinct Utilization of Scaffold Proteins

2008 ◽  
Vol 29 (5) ◽  
pp. 1338-1353 ◽  
Author(s):  
Berta Casar ◽  
Imanol Arozarena ◽  
Victoria Sanz-Moreno ◽  
Adán Pinto ◽  
Lorena Agudo-Ibáñez ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Subcellular Localization ◽  
Lipid Rafts ◽  
Growth Factor Receptor ◽  
Underlying Mechanism ◽  
Scaffold Proteins ◽  
Extracellular Signal Regulated Kinase ◽  
Cytosolic Phospholipase ◽  
Extracellular Signal ◽  
Epidermal Growth

ABSTRACT Subcellular localization influences the nature of Ras/extracellular signal-regulated kinase (ERK) signals by unknown mechanisms. Herein, we demonstrate that the microenvironment from which Ras signals emanate determines which substrates will be preferentially phosphorylated by the activated ERK1/2. We show that the phosphorylation of epidermal growth factor receptor (EGFr) and cytosolic phospholipase A2 (cPLA2) is most prominent when ERK1/2 are activated from lipid rafts, whereas RSK1 is mainly activated by Ras signals from the disordered membrane. We present evidence indicating that the underlying mechanism of this substrate selectivity is governed by the participation of different scaffold proteins that distinctively couple ERK1/2, activated at defined microlocalizations, to specific substrates. As such, we show that for cPLA2 activation, ERK1/2 activated at lipid rafts interact with KSR1, whereas ERK1/2 activated at the endoplasmic reticulum utilize Sef-1. To phosphorylate the EGFr, ERK1/2 activated at lipid rafts require the participation of IQGAP1. Furthermore, we demonstrate that scaffold usage markedly influences the biological outcome of Ras site-specific signals. These results disclose an unprecedented spatial regulation of ERK1/2 substrate specificity, dictated by the microlocalization from which Ras signals originate and by the selection of specific scaffold proteins.

scholarly journals Observations on the Effects of Residualization and Dehalogenation on the Utility of N-Succinimidyl Ester Acylation Agents for Radioiodination of the Internalizing Antibody Trastuzumab

Molecules ◽  
2019 ◽  
Vol 24 (21) ◽  
pp. 3907 ◽  
Author(s):  
Satish K. Chitneni ◽  
Eftychia Koumarianou ◽  
Ganesan Vaidyanathan ◽  
Michael R. Zalutsky
Keyword(s):  
Growth Factor Receptor ◽  
Carcinoma Cells ◽  
Breast Cancers ◽  
Human Breast ◽  
Her2 Positive ◽  
Two Factors ◽  
Epidermal Growth ◽  
Prolonged Retention ◽  
Human Breast Carcinoma Cells

Trastuzumab is an antibody used for the treatment of human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancers. Since trastuzumab is an internalizing antibody, two factors could play an important role in achieving high uptake and prolonged retention of radioactivity in HER2-positive tumors after radioiodination—residualizing capacity after receptor-mediated internalization and susceptibility to dehalogenation. To evaluate the contribution of these two factors, trastuzumab was radiolabeled using the residualizing reagent N-succinimidyl 4-guanidinomethyl-3-[*I]iodobenzoate ([*I]SGMIB) and the nonresidualizing reagent N-succinimidyl-3-[*I]iodobenzoate ([*I]SIB), both of which are highly dehalogenation-resistant. Paired-label uptake and intracellular retention of [125I]SGMIB-trastuzumab and [131I]SIB-trastuzumab was compared on HER2-expressing BT474 human breast carcinoma cells. Tumor uptake and normal tissue distribution characteristics for the two labeled conjugates were assessed in mice bearing BT474M1 xenografts. The internalization and intracellular retention of initially-bound radioactivity in BT474 cells was similar for the two labeled conjugates up to 4 h, but were significantly higher for [125I]SGMIB-trastuzumab at 6 and 24 h. Similarly, [*I]SGMIB labeling resulted in significantly higher uptake and retention of radioactivity in BT474M1 xenografts at all studied time points. Moreover, tumor-to-tissue ratios for [125I]SGMIB-trastuzumab were consistently higher than those for [131I]SIB-trastuzumab starting at 12 h postinjection. Thus, optimal targeting of HER2-positive breast cancers with a radioiodinated trastuzumab conjugate requires an acylation agent that imparts residualizing capacity in addition to high stability towards dehalogenation in vivo.

scholarly journals Lysophosphatidic acid stimulation of NHE3 exocytosis in polarized epithelial cells occurs with release from NHERF2 via ERK-PLC-PKCδ signaling

2014 ◽  
Vol 307 (1) ◽  
pp. C55-C65 ◽  
Author(s):  
Boyoung Cha ◽  
Tiane Chen ◽  
Rafiquel Sarker ◽  
Jianbo Yang ◽  
Daniel Raben ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Lysophosphatidic Acid ◽  
Pdz Domain ◽  
Growth Factor Receptor ◽  
Scaffold Proteins ◽  
Regulatory Factor ◽  
Opossum Kidney ◽  
Epidermal Growth ◽  
Small Intestinal ◽  
Stimulation Of

The Na+/H+ exchanger 3 (NHE3) is a brush border (BB) Na+/H+ antiporter that accounts for the majority of physiologic small intestinal and renal Na+ absorption. It is regulated physiologically and in disease via changes in endocytosis/exocytosis. Paradoxically, NHE3 is fixed to the microvillar (MV) actin cytoskeleton and has little basal mobility. This fixation requires NHE3 binding to the multi-PDZ domain scaffold proteins Na+/H+ exchanger regulatory factor (NHERF)1 and NHERF2 and to ezrin. Coordinated release of NHE3 from the MV cytoskeleton has been demonstrated during both stimulation and inhibition of NHE3. However, the signaling molecules involved in coordinating NHE3 trafficking and cytoskeletal association have not been identified. This question was addressed by studying lysophosphatidic acid (LPA) stimulation of NHE3 in polarized renal proximal tubule opossum kidney (OK) cells that occurs via apical LPA5 receptors and is NHERF2 dependent and mediated by epidermal growth factor receptor (EGFR), Rho/Rho-associated kinase (ROCK), and ERK. NHE3 activity was determined by BCECF/fluorometry and NHE3 microvillar mobility by FRAP/confocal microscopy using NHE3-EGFP. Apical LPA (3 μM)/LPA5R stimulated NHE3 activity, increased NHE3 mobility, and decreased the NHE3/NHERF2 association. The LPA stimulation of NHE3 was also PKCδ dependent. PKCδ was necessary for LPA stimulation of NHE3 mobility and NHE3/NHERF2 association. Moreover, the LPA-induced translocation to the membrane of PKCδ was both ERK and phospholipase C dependent with ERK acting upstream of PLC. We conclude that LPA stimulation of NHE3 exocytosis includes a signaling pathway that regulates fixation of NHE3 to the MV cytoskeleton. This involves a signaling module consisting of ERK-PLC-PKCδ, which dynamically and reversibly releases NHE3 from NHERF2 to contribute to the changes in NHE3 MV mobility.

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