• 대한방사성의약품학회지
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• 제2권2호
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• pp.63-68
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• 2016

Peptides have been developed for in vivo imaging probes against to the specific biomarker in the biological process of living systems. Peptide based imaging probes have been applied to identify and detect their active sites using imaging modalities, such as PET, SPECT and MRI. Especially, tumor receptor imaging with the peptides has been widely used to specific tumor detection. This review discusses the targeting peptides that have been successfully characterized for tumor diagnosis by receptor imaging.

• 대한핵의학회지
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• 제36권1호
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• pp.8-18
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• 2002

Early and accurate diagnosis of tumors using positron omission tomography (PET) has been the focus of considerable interest due to its high metastasis and mortality rates at late detection. PET radiopharmaceuticals-which exhibit a high tumor-to-background uptake ratio, and appropriate metabolic characteristics, and pharmacokinetics-are attractive tools for tumor imaging. Tumor imaging by these radiopharmaceuticals are based on metabolic and receptor imaging. The former is based on accelerated metabolism in tumor tissue compared to normal tissue and the rate roughly corresponding to the rate of growth of tumors. Radiopharmaceuticals for this purpose include radiolabeled sugars, amino acids, and nucleosides which detect increased glucose utilization, protein synthesis, and DNA synthesis, respectively. Tumor receptor imaging is based on the proliferation of tumor cells regulated by many hormones and growth factors, which bind to the corresponding receptors and exhibit the biological responses Radiopharmaceuticals used to image the tumor receptor systems may be ligands for the specific receptors and antibodies for the growth factor receptors. Some antitumor agents have been labeled with radionuclides and used to study in vivo biodistribution and pharmacokinetics in humans. This overview describes typical PET radiopharmaceuticals used for tumor imaging based on their uptake mechanisms.

• Korean Journal of Radiology
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• 제25권7호
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• pp.623-633
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• 2024

This study systematically reviewed the role of diffusion-weighted imaging (DWI) in the assessment of molecular prognostic biomarkers in breast cancer, focusing on the correlation of apparent diffusion coefficient (ADC) with hormone receptor status and prognostic biomarkers. Our meta-analysis includes data from 52 studies examining ADC values in relation to estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER2), and Ki-67 status. The results indicated significant differences in ADC values among different receptor statuses, with ER-positive, PgR-positive, HER2-negative, and Ki-67-positive tumors having lower ADC values compared to their negative counterparts. This study also highlights the potential of advanced DWI techniques such as intravoxel incoherent motion and non-Gaussian DWI to provide additional insights beyond ADC. Despite these promising findings, the high heterogeneity among the studies underscores the need for standardized DWI protocols to improve their clinical utility in breast cancer management.

• Nuclear Medicine and Molecular Imaging
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• 제41권2호
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• pp.166-171
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• 2007

GABA is primary an inhibitory neurotransmitter that is localized in inhibitory interneurons. GABA is released from presynaptic terminals and functions by binding to GABA receptors. There are two types of GABA receptors, $GABA_{A}-receptor$ that allows chloride to pass through a ligand gated ion channel and $GABA_{B}-receptor$ that uses G-proteins for signaling. The $GABA_{A}$-receptor has a GABA binding site as well as a benzodiazepine binding sites, which modulate $GABA_{A}$-receptor function. Benzodiazepine GABAA receptor imaging can be accomplished by radiolabeling derivates that activates benzodiazepine binding sites. There has been much research on flumazenil (FMZ) labeled with $^{11}C-FMZ$, a benzodiazepine derivate that is a selective, reversible antagonist to GABAA receptors. Recently, $^{18}F-fluoroflumazenil$ (FFMZ) has been developed to overcome $^{11}C's$ short half-life. $^{18}F-FFMZ$ shows high selective affinity and good pharmacodynamics, and is a promising PET agent with better central benzodiazepine receptor imaging capabilities. In an epileptic focus, because the GABA/benzodiazepine receptor amount is decreased, using $^{11}C-FMZ$ PET instead of $^{18}F-FDG$ PET, restrict the foci better and may also help find lesions better than high resolution MR. $GABA_{A}$ receptors are widely distributed in the cerebral cortex, and can be used as an viable neuronal marker. Therefore it can be used as a neuronal cell viability marker in cerebral ischemia. Also, GABA-receptors decrease in areas where neuronal plasticity develops, therefore, $GAB_{A}$ imaging can be used to evaluate plasticity. Besides these usages, GABA receptors are related with psychological diseases, especially depression and schizophrenia as well as cerebral palsy, a motor-related disorder, so further in-depth studies are needed for these areas.

• Nuclear Medicine and Molecular Imaging
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• 제42권3호
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• pp.185-191
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• 2008

While indirect targeting strategies using reporter-genes are taking center stage in current molecular imaging research, another vital strategy has long involved direct imaging of specific receptors using radiolabeled ligands. Recently, there is renewal of immense interest in this area with particular attention to the epidermal growth factor receptor (EGFR), a transmembrane glycoprotein critically involved in the regulation of many cellular functions and malignancies. Recently, two novel classes of EGFR-targeting anticancer drugs have entered clinical trials with great expectations. These are monoclonal antibodies such as cetuximab that target the extracellular domain, and small molecule tyrosine kinase inhibitors such as gefitinib (lressa) and erlotinib (Tarceva) that target the catalytic domain of the receptor. However, early results have showed disappointing survival benefits, disclosing a major challenge for this therapeutic strategy; namely, the need to identify tumors that are most likely to respond to the agents. To address this important clinical issue, several noninvasive imaging techniques are under investigation including radiolabeled probes based on small molecule tyrosine kinase inhibitors, anti-EGFR antibodies, and EGF peptides. This review describes the current status, limitations, and future prospects in the development of radiotracer methods for EGFR imaging.

• 대한핵의학회지
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• 제33권1호
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• pp.11-27
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• 1999

Peptide imaging is a new diagnostic modality in nuclear medicine. $^{111}In$-pentetreotide ($Octreoscan^R$) is the first commercially available peptide radiopharmaceutical. This review article presents the results of previous studies using $^{111}In$-pentetreotide for several disease states, including neuroendocrine tumors, breast cancer and malignant lymphoma. The use of hand-held probe during surgery and the preliminary results of radiotherapy using radiolabeled somatostatin analogues are also reviewed. It can be concluded that somatostatin receptor scintigraphy is a promising diagnostic tool for localizing primary tumors that express receptors for somatostatin, staging secondary spread of tumor tissue, following up after therapy and identifying patients who may benefit from therapy with unlabelled or radiolabeled octreotide. The somatostatin receptor imaging will stimulate the development of new radiopharmaceuticals for other receptors and enhance the therapeutic use of radiolabeled peptides.

• 대한방사성의약품학회지
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• 제7권2호
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• pp.127-131
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• 2021

Neuroendocrine tumor is one of popular diseases, and somatostatin receptor antagonists have been considered as promising agents for neuroendocrine tumors. Imaging of somatostatin receptor is useful approach on the diagnosis and therapy of neuroendocrine tumors. Thus, several radiolabeled somatostatin derivatives have been developed by scientists, and used for patients with neuroendocrine tumors. In particular, some radiopharmaceuticals for neuroendocrine tumors were approved by FDA. In this highlight review, the development of important radiolabeled somatostatin derivatives is described.

• Asian Pacific Journal of Cancer Prevention
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• 제15권8호
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• pp.3555-3559
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• 2014

Background: The triple-negative breast cancer (TNBC) is an aggressive cancer characterized by the absence of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). Preoperative mammography and ultrasound features of TNBC may potentially suggest characteristics of the disease and assist in treatment decisions. Materials and Methods: The study covered 153 patients with TNBC from May 2011 to May 2012 who were confirmed by postoperative pathology results in our hospital. We compared the radiological findings among the patients and sought to determine the significant iconographic features. The biomarkers p53 and Ki-67 are regarded as significant factors in TNBC. They were therefore used to divide the TNBC into four groups for assessment of relationships with TNBC imaging features. Results: On mammography, most TNBCs exhibit obscure (44.3%) masses. On ultrasound, the majority of masses (95.4%) were predominantly indistinct (50.7%), irregular (76.0%) or featuring posterior echo enhancement/shadowing. Color Doppler flow imaging (CDFI) emphasized hypervascular (32.9%) masses. Differences in CDFI by ultrasound among the four groups were statistically significant (p=0.009). There were obvious differences in the percentages of spiculated margin (p=0.049) and intensive posterior echo (p=0.006) with spotty flow imaging by ultrasound between the Ki-67 (+) p53 (+) and other groups. Conclusions: A combination of mammography and ultrasound revealed the imaging characteristics of TNBC included an obscure mass with less attenuated posterior echoes and some vascularity. A worse prognosis was associated with spiculated margin and intensive posterior echoes with spotty flow imaging.

• Biomolecules & Therapeutics
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• 제25권5호
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• pp.497-503
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• 2017

Recent reports claimed that glucosylsphingosine (GS) is highly accumulated and specifically evoking itch-scratch responses in the skins of atopic dermatitis (AD) patients. However, it was unclear how GS can trigger itch-scratch responses, since there were no known molecular singling pathways revealed yet. In the present study, it was verified for the first time that GS can activate mouse serotonin receptor 2a (mHtr2a) and 2b (mHtr2b), but not 2c (mHtr2c) that are expressed in HEK293T cells. Specifically, effects of GS on all mouse serotonin receptor 2 subfamily were evaluated by calcium imaging techniques. The GS-induced intracellular calcium increase was dose-dependent, and antagonists such as ketanserin (Htr2a antagonist) and RS-127445 (Htr2b antagonist) significantly blocked the GS-induced responses. Moreover, the proposed GS-induced responses appear to be mediated by phospholipase C (PLC), since pretreatment of a PLC inhibitor U-73122 abolished the GS-induced responses. Additionally, the GS-induced calcium influx is probably mediated by endogenous TRPC ion channels in HEK293T cells, since pretreatment of SKF-96365, an inhibitor for TRPC, significantly suppressed GS-induced response. In conclusion, the present study revealed for the first time that GS can stimulate mHtr2a and mHtr2b to induce calcium influx, by utilizing PLC-dependent pathway afterwards. Considering that GS is regarded as a pruritogen in AD, the present study implicates a novel GS-induced itch signaling pathway.

• Bulletin of the Korean Chemical Society
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• 제29권6호
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• pp.1107-1114
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• 2008

It is important to identify selective ligands for the estrogen receptor subtypes ER$\alpha$ or ER$\beta$ to evaluate them as pharmaceutical targets in breast cancer. To develop ER$\beta$-selective ligands as PET imaging agents, a series of aryl indazole estrogen analogues substituted at the C3 position with fluoroethyl and fluoropropyl groups were synthesized and evaluated for their relative binding affinities and selectivities for ER$\alpha$ vs ER$\beta$. The fluoroethylated indazole estrogen (FEIE, 1i) and fluoropropylated indazole estrogen (FPIE, 1h) showed 41- fold and 17-fold ER$\beta$/ER$\alpha$ selectivity, respectively. However, their binding affinities to ER$\alpha$ and ER$\beta$ were very low.