Novel 99mTc-Labeled Mannose Derivative as a Highly Promising Single Photon Emission Computed Tomography Probe for Tumor Imaging.

18F-2-fluoro-2-deoxy-d-glucose ([18F]FDG) has been the most used positron emission tomography imaging agent for clinical applications. Single photon emission computed tomography (SPECT) imaging is cheaper and used more widely for diagnostic use, but there is no SPECT tumor imaging agent for clinical applications comparable to [18F]FDG. Mannose is a C2 epimer of glucose and can also be transported into tumor cells via glucose transporters (GLUTs). To develop a novel SPECT tumor imaging agent with satisfactory tumor uptake and tumor/nontarget ratios, here a mannose derivative (CN7DM) was synthesized and radiolabeled with technetium-99m to prepare [99mTc]Tc-CN7DM. The six-coordinated structure of [99mTc]Tc-CN7DM was confirmed by the corresponding rhenium compound (Re-CN7DM). [99mTc]Tc-CN7DM was transported into cancer cells via GLUTs and may be trapped in the cancer cells by electrostatic attraction. The probe exhibited high uptake in tumors and low uptake in nontarget tissues in mice bearing different tumors, indicating that [99mTc]Tc-CN7DM exhibited promising potential for SPECT tumor imaging and warranted further clinical investigation.

Preparation and Evaluation of a Novel 99mTc-Labeled Niraparib Isonitrile Complex as a Potential PARP-1 Imaging Agent.

Poly ADP-ribose polymerase (PARP) plays an important role in the DNA repair process and has become an attractive target for cancer therapy in recent years. Given that niraparib has good clinical efficacy as a PARP inhibitor, this study aimed to develop radiolabeled niraparib derivatives for tumor imaging to detect PARP expression and improve the accuracy of stratified patient therapy. The niraparib isonitrile derivative (CNPN) was designed, synthesized, and radiolabeled to obtain the [99mTc]Tc-CNPN complex with high radiochemical purity (>95%). It was lipophilic and stable in vitro. In HeLa cell experiments, the uptake of [99mTc]Tc-CNPN was effectively inhibited by the ligand CNPN, indicating the binding affinity for PARP. According to the biodistribution studies of HeLa tumor-bearing mice, [99mTc]Tc-CNPN has moderate tumor uptake and can be effectively inhibited, demonstrating its specificity for targeting PARP. The SPECT imaging results showed that [99mTc]Tc-CNPN had tumor uptake at 2 h postinjection. All of the results of this study indicated that [99mTc]Tc-CNPN is a promising tumor imaging agent that targets PARP.

Chitosan oligosaccharide improves intestinal homeostasis to achieve the protection for the epithelial barrier of female Drosophila melanogaster via regulating intestinal microflora.

Chitosan oligosaccharide (COS) is a new type of marine functional oligosaccharide with biological activities such as regulating intestinal microflora and improving intestinal immunity. In this study, female Drosophila melanogaster was used as a model organism to evaluate the effect of COS on intestinal injury by H2O2 induction, and its mechanism was explored through the analysis of intestinal homeostasis. The results showed that 0.25% of COS could effectively prolong the lifespan of stressed female D. melanogaster by increasing its antioxidant capacity and maintaining intestinal homeostasis, which included protecting the mechanical barrier, promoting the chemical barrier, and regulating the biological barrier by affecting its autophagy and the antioxidant signaling pathway. Additionally, the protective effect of COS on the intestinal barrier and homeostasis of D. melanogaster under oxidative stress status is directly related to its regulation of the intestinal microflora, which could decrease excessive autophagy and activate the antioxidant system to promote health. IMPORTANCE: The epithelial barrier plays an important role in the organism's health. Chitosan oligosaccharide (COS), a new potential prebiotic, exhibits excellent antioxidant capacity and anti-inflammatory effects. Our study elucidated the protective mechanisms of COS on the intestinal barrier of Drosophila melanogaster under oxidative stress, which could provide new insights into COS application in various industries, such as food, agriculture, and medicine.

Synthesis and Preclinical Evaluation of Novel 99mTc-Labeled FAPI-46 Derivatives with Significant Tumor Uptake and Improved Tumor-to-Nontarget Ratios.

Fibroblast activation protein (FAP), which is expressed on the cell membranes of fibroblasts in most solid tumors, has become an important target for tumor diagnosis and treatment. However, previously reported 99mTc-labeled FAPI-04 complexes have high blood uptake, limiting their use in the clinic. In this work, six 99mTc-labeled FAPI-46 derivatives with different linkers (different amino acids, peptides, or polyethylene glycol) were prepared and evaluated. They had good in vitro stability, hydrophilicity, and good specificity for FAP. The biodistribution and MicroSPECT images revealed that they all had high specific tumor uptake for FAP, and their blood uptake was significantly decreased. Among them, [99mTc]Tc-6-1 exhibited the highest target-to-nontarget ratios (tumor/blood: 6.06 ± 1.19; tumor/muscle: 10.26 ± 0.44) and good tumor uptake (16.15 ± 0.83%ID/g), which also had significantly high affinity for FAP, good in vivo stability, and safety. Therefore, [99mTc]Tc-6-1 holds great potential as a promising molecular tracer for FAP tumor imaging.

Radiosynthesis and Bioevaluation of 99mTc-Labeled Isocyanide Ubiquicidin 29-41 Derivatives as Potential Agents for Bacterial Infection Imaging.

To develop a novel 99mTc-labeled ubiquicidin 29-41 derivative for bacterial infection single-photon emission computed tomography (SPECT) imaging with improved target-to-nontarget ratio and lower nontarget organ uptake, a series of isocyanide ubiquicidin 29-41 derivatives (CNnUBI 29-41, n = 5-9) with different carbon linkers were designed, synthesized and radiolabeled with the [99mTc]Tc(I)+ core, [99mTc][Tc(I)(CO)3(H2O)3]+ core and [99mTc][Tc(V)N]2+ core. All the complexes are hydrophilic, maintain good stability and specifically bind Staphylococcus aureus in vitro. The biodistribution in mice with bacterial infection and sterile inflammation demonstrated that [99mTc]Tc-CN5UBI 29-41 was able to distinguish bacterial infection from sterile inflammation, which had an improved abscess uptake and a greater target-to-nontarget ratio. SPECT imaging study of [99mTc]Tc-CN5UBI 29-41 in bacterial infection mice showed that there was a clear accumulation in the infection site, suggesting that this radiotracer could be a potential radiotracer for bacterial infection imaging.

The Preparation and Execution of Exploratory Human Studies on Novel 99mTc-Labeled Glucosamine Derivatives Containing Different Phenyl Isonitriles as Promising Tumor Imaging Agents.

As the "molecule of the century", 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG) is a radioactive 18F-labeled glucose derivative with a wide range of applications for positron emission tomography (PET) imaging. Single photon emission computed tomography (SPECT) imaging is widely used, but there is no clinical probe comparable to [18F]FDG. In our previous work, [99mTc]Tc-CN5DG and [99mTc]Tc-CN7DG were successfully developed and achieved high-quality SPECT images. However, they still have the disadvantage of low tumor uptake and/or high uptake by nontarget organs. To develop novel tumor imaging agents with high tumor uptake and excellent tumor/nontarget ratios, in this study, starting from d-glucosamine hydrochloride, four phenyl group-containing isonitrile ligands were designed, synthesized, and radiolabeled with 99mTc. All the complexes had high radiochemical purity and good hydrophilicity and stability. Biodistribution experiments showed that [99mTc]Tc-L4 (i.e., [99mTc]Tc-CNMBDG) had the highest tumor uptake and tumor/background ratios among the four probes. In SPECT imaging studies, the tumor detected by [99mTc]Tc-L4 was more clearly visible than that of [99mTc]Tc-CN7DG because of the inappreciable interference from abdominal uptake. Preliminary clinical studies of [99mTc]Tc-L4 have been conducted and successfully showed the lesion location in a patient with non-small-cell lung cancer. In summary, [99mTc]Tc-L4 is expected to be a promising tumor SPECT imaging agent.

Preparation and Evaluation of [18F]AlF-NOTA-PBB for PET Imaging of Cyclin-dependent Kinase 4/6 in Tumors.

Cyclin-dependent kinases (CDKs), especially cyclin-dependent kinase 4/6 (CDK4/6), have been targets for the development of specific tumor imaging agents. Palbociclib is a highly selective CDK4/6 inhibitor. In this study, to develop a novel 18F-labeled palbociclib derivative for specific tumor imaging, we designed and synthesized a ligand (NOTA-PBB) consisting of palbociclib as the targeted pharmacophore and NOTA as the macrocyclic bifunctional chelator. The corresponding [18F]AlF-NOTA-PBB complex was prepared with high radiochemical purity (98.4 ± 0.15%) and yield (58.7 ± 4.5%) within 35 min without requiring HPLC purification through a simple one-step 18F-labeling strategy of NOTA-AlF chelation chemistry. The radiotracer was lipophilic (log P = 0.095 ± 0.003) and had good stability in vitro and in vivo. The cellular uptake studies performed on the MCF-7 breast cancer cell line (ER-positive and HER2-negative) showed that radioactive uptake was blocked by preincubating with a molar dose of palbociclib and it had a nanomolar binding affinity to CDK4/6 (IC50 = 16.23 ± 1.84 nM), demonstrating a CDK4/6-mediated uptake mechanism. Its ex vivo biodistribution in nude mice-bearing MCF-7 tumors showed obvious tumor uptake and a high tumor/muscle ratio of [18F]AlF-NOTA-PBB, and tumor uptake was inhibited with 100 µg of palbociclib, demonstrating specific binding to CDK4/6. Radioactivity accumulation in MCF-7 tumors was observed in PET imaging with [18F]AlF-NOTA-PBB. Based on the results of this work, [18F]AlF-NOTA-PBB has the promising capability as a CDK4/6-targeted tumor imaging agent.

A Simple Kit Formulation for Preparation and Exploratory Human Studies of a Novel 99mTc-Labeled Fibroblast Activation Protein Inhibitor Tracer for Imaging of the Fibroblast Activation Protein in Cancers.

Fibroblast activation protein (FAP) is a potential target for tumor diagnosis and treatment because it is selectively expressed on the cell membrane of cancer-associated fibroblasts in most solid tumor stroma. The aim of this study was to develop a 99mTc-labeled fibroblast activation protein inhibitor (FAPI) tracer, evaluate its imaging efficacy in nude mice, and further explore its biodistribution in healthy volunteers and uptake in tumor patients. An FAPI-derived ligand (DP-FAPI) containing d-proline was designed and synthesized as a linker, and a stable hydrophilic 99mTc-labeled complex ([99mTc]Tc-DP-FAPI) was obtained by kit formulation. In vitro cellular uptake and saturation binding assays were performed in FAP-transfected HT-1080 cells (FAP-HT-1080). The biodistribution was characterized, and micro-single-photon emission computed tomography (SPECT) imaging was performed in BALB/c nude mice bearing U87 MG tumors. Furthermore, a first-in-man application was performed in four healthy volunteers and three patients with gastrointestinal tumors. In vitro, the nanomolar Kd values of [99mTc]Tc-DP-FAPI indicated that it had significantly high target affinity for FAP. Biodistribution and micro-SPECT imaging studies showed that [99mTc]Tc-DP-FAPI exhibited high uptake and high tumor-to-nontargeted ratios. The calculated effective dose for [99mTc]Tc-DP-FAPI was approximately <5 mSv in four healthy volunteers. In three patients with gastrointestinal tumors, [99mTc]Tc-DP-FAPI quantitative SPECT/CT revealed high and reliable uptake. [99mTc]Tc-DP-FAPI exhibited high selectivity and affinity for FAP in vitro. The safety and effectiveness of [99mTc]Tc-DP-FAPI in primary tumor imaging have been confirmed by animal and clinical studies, revealing the potential clinical application value of this tracer.

Preparation and Bioevaluation of a Novel 99mTc-Labeled Glucose Derivative Containing Cyclohexane as a Promising Tumor Imaging Agent.

To develop novel tumor imaging agents with high tumor uptake and excellent tumor/non-target ratios, a glucose derivative containing cyclohexane (CNMCHDG) was synthesized and labeled with Tc-99m. [99mTc]Tc-CNMCHDG was prepared by a kit formulation that was straightforward to operate and fast. Without purification, [99mTc]Tc-CNMCHDG had a high radiochemical purity of over 95% and great in vitro stability and hydrophilicity (log P = -3.65 ± 0.10). In vitro cellular uptake studies showed that the uptake of [99mTc]Tc-CNMCHDG was significantly inhibited by pre-treatment with D-glucose and increased by pre-treatment with insulin. Preliminary cellular studies have demonstrated that the mechanism by which the complex enters into cells may be related to GLUTs. The results of biodistribution and SPECT imaging studies displayed high tumor uptake and good retention of [99mTc]Tc-CNMCHDG in A549 tumor-bearing mice (4.42 ± 0.36%ID/g at 120 min post-injection). Moreover, [99mTc]Tc-CNMCHDG exhibited excellent tumor-to-non-target ratios and a clean imaging background and is a potential candidate for clinical transformation.

Synthesis and Evaluation of 99mTc-Labeled FAP Inhibitors with Different Linkers for Imaging of Fibroblast Activation Proteins in Tumors.

Fibroblast activation protein (FAP) is a potential target for tumor diagnosis and treatment due to its selective expression on cancer-associated fibroblasts (CAFs) in most solid tumor stroma. Two FAP inhibitor (FAPI) derived ligands (L1 and L2) containing different lengths of DPro-Gly (PG) repeat units as linkers were designed and synthesized with high affinity for FAP. Two stable hydrophilic 99mTc-labeled complexes ([99mTc]Tc-L1 and [99mTc]Tc-L2) were obtained. In vitro cellular studies show that the uptake mechanism is correlated with FAP uptake, and [99mTc]Tc-L1 shows a higher cell uptake and specific binding to FAP. A nanomolar Kd value for [99mTc]Tc-L1 indicates its significantly high target affinity for FAP. The biodistribution and microSPECT/CT images obtained for U87MG tumor mice show that [99mTc]Tc-L1 has high tumor uptake with specificity to FAP and high tumor-to-nontarget ratios. As an inexpensive, easily made, and widely available tracer, [99mTc]Tc-L1 holds great promise for clinical applications.

Current status and progress in using radiolabelled PARP-1 inhibitors for imaging PARP-1 expression in tumours.

Poly(ADP-ribose) polymerase-1 (PARP-1) is a key enzyme in the DNA repair process, and the overexpression of PARP-1 in several tumours makes this enzyme a promising molecular target. Recently, several PARP-1 inhibitors, such as olaparib, rucaparib, niraparib and talazoparib, have been clinically approved as anticancer drugs. Several of these inhibitors have been radiolabelled for noninvasive imaging of PARP-1 expression in several types of tumours. In this review, the background and progress for using various radiolabelled PARP-1 inhibitors for cancer diagnosis are discussed and future development directions are proposed.

Novel 99mTc labeled complexes with bisphosphonate isocyanide: Radiosynthesis and evaluation as potential bone-seeking agents.

In order to develop 99mTc-labeled complexes with bisphosphonate isocyanide as novel bone imaging agents, two bisphosphonate isocyanide derivatives (CNALN and CNPAM) were synthesized and radiolabeling was performed for preparing the corresponding [99mTc]Tc(I) complexes. [99mTc]Tc-CNALN and [99mTc]Tc-CNPAM were obtained with high radiochemical purity and showed good in vitro stability. Both of them were hydrophilic and had high affinity to hydroxyapatite. The biodistribution studies in mice revealed [99mTc]Tc-CNALN showed higher bone/background ratios at 60 min post-injection. In single photon emission computed tomography (SPECT) imaging study, [99mTc]Tc-CNALN had an obvious accumulation in bone, suggesting it would be a promising bone-seeking agent.

A Study on Curcumol Influencing Proliferation and Apoptosis of Hepatocellular Carcinoma Cells through DJ-1/PTEN/PI3K/AKT Pathway.

Objective: To study the mechanism of curcumol affecting the proliferation and apoptosis of liver cancer cells through the DJ-1/PTEN/PI3K/AKT pathway. Method: HepG2 cells were cultured in vitro, treated with curcumol at concentrations of 10, 30, and 100 µg/mL, and DMSO was used as a control. The levels of cell proliferation and apoptosis were measured by CCK-8 and flow cytometry, respectively. RT-PCR and western blot were used to detect PTEN, p-AKT, DJ-1, and PI3K gene and protein expression changes. Result: (1) Compared with the DMSO blank control group, the proliferation level of liver cancer cells in the 10 µg/mL curcumol group decreased, and the proportion of apoptosis increased (p <0.05). (2) Compared with the blank control group and the 10 and 30 µg/mL concentration groups, the proliferation level of liver cancer cells in the 100 µg/mL curcumol group was significantly reduced, and the proportion of cell apoptosis was significantly increased (p < 0.05). (3) Curcumol can significantly increase the expression of PTEN gene and protein in liver cancer cells and reduce the expression of DJ-1 and PI3K genes and protein in liver cancer cells (p < 0.05). Conclusion: Curcumol can regulate DJ-1, PTEN, PI3K, and AKT signal transduction pathways, inhibit cell proliferation, and cause a significant increase in the proportion of cell apoptosis, and the pharmacodynamic effect of curcumol is dependent on the time and dose of action.

Preparation and Bioevaluation of 99mTc-Labeled FAP Inhibitors as Tumor Radiotracers to Target the Fibroblast Activation Protein.

Fibroblast activation protein (FAP) is overexpressed in cancer-associated fibroblasts (CAFs) in a majority of human epithelial cancers. With low expression in normal organs, FAP has become a promising molecular target for tumor theranostics. To develop a lower cost and more widely available alternative to positron emission tomography (PET), two isocyanide-containing FAP inhibitors (CN-C5-FAPI and CN-PEG4-FAPI) were synthesized and radiolabeled with 99mTc to obtain [99mTc][Tc-(CN-C5-FAPI)6]+ and [99mTc][Tc-(CN-PEG4-FAPI)6]+ in high yields (>95%). They showed good stability in saline and mouse serum. The partition coefficient (log P) values of [99mTc][Tc-(CN-C5-FAPI)6]+ and [99mTc][Tc-(CN-PEG4-FAPI)6]+ were -0.86 ± 0.03 and -2.38 ± 0.07, respectively, indicating that they were good hydrophilic complexes. The low nanomolar IC50 values of CN-C5-FAPI and CN-PEG4-FAPI indicated that they had specificity to FAP. In vitro cellular uptake and blocking experiments implied a FAP-targeted uptake mechanism. The nanomolar Kd values from the saturation binding assay indicated that they had significantly high target affinity to FAP. The biodistribution and blocking study in BALB/c nude mice bearing U87MG tumors showed that both exhibited specific tumor uptake. [99mTc][Tc-(CN-PEG4-FAPI)6]+ showed a higher tumor uptake and a higher tumor/nontarget ratio than [99mTc][Tc-(CN-C5-FAPI)6]+. The results of micro-single-photon emission computed tomography (SPECT) imaging studies of [99mTc][Tc-(CN-C5-FAPI)6]+ and [99mTc][Tc-(CN-PEG4-FAPI)6]+ were in accordance with the biodistribution results, suggesting that [99mTc][Tc-(CN-PEG4-FAPI)6]+ is a promising tumor imaging agent for targeting FAP.

Colorimetric detection of glutathione based on its inhibitory effect on the peroxidase-mimicking properties of WS2 nanosheets.

A highly sensitive colorimetric assay is described for the determination of glutathione (GSH). It is based on the use of tungsten disulfide (WS2) which is a peroxidase mimic. It catalyzes the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by hydrogen peroxide to form a blue-colored product (oxTMB) at near neutral pH values. In the presence of the analyte GSH, it is transformed to its oxidized form (GSSG), while the blue oxTMB is increasingly reduced and eventually is converted to colorless TMB. This can readily be detected with bare eyes. GSH can be determined spectroscopically (at 652 nm) by this method at concentrations down to 61 pM, and the response is linear in the 100 pM to 10 nM GSH concentration range. The assay is cost-effective and simple. Conceivably, it provides a promising tool for the determination of GSH in food and medical samples. Graphical abstract Schemaric of a sensitive method for colorimetric detection of glutathione (GSH) based on WS2-catalyzed oxidation of TMB by H2O2 and the reduction of blue oxTMB by GSH.

MicroRNA-223-3p Regulates Ovarian Cancer Cell Proliferation and Invasion by Targeting SOX11 Expression.

MicroRNAs (miRNAs) often display different expression in many cancers and other diseases in current research studies. miR-223 expression is upregulated in rheumatoid arthritis. Also, miR-223 expression has been demonstrated to be highly expressed in pancreatic cancer and gastric cancer in comparison with normal tissue. However, whether miR-223 displays different expression in ovarian cancer and what its underlying functions are in ovarian cancer have remained unclear. In this study, we demonstrated that miR-223-3p was upregulated in ovarian cancer tissue. Next, we explored the functional role of miR-223-3p in ovarian cancer using SKOV3 and OVCAR3 cell lines. Our results suggested that miR-223-3p mimic promoted ovarian cancer cell proliferation, migration, and invasion in vitro. However, miR-223-3p inhibitor displayed the opposite effects. In addition, we demonstrated that miR-223-3p mimic promoted tumor growth in vivo. Furthermore, we found SOX11 (sex determining region Y-box 11) was inversely expressed with miR-223-3p in ovarian cancer (OC) cell lines and tissue specimens. miR-223-3p mimic decreased SOX11 expression. Overexpressing SOX11 inhibited ovarian cancer cell proliferation and invasion, which indicated that miR-223-3p regulated OC cell proliferation and invasion through targeting SOX11 expression. In conclusion, the findings of the present study demonstrated that miR-223-3p could be a potential therapeutic for ovarian cancer.