Specific Targeting of STAT3 in B Cells Suppresses Progression of B Cell Lymphoma.

The signal transducer and activator of transcription 3 (STAT3), which regulates multiple oncogenic processes, has been found to be constitutively activated in lymphoma, suggesting its potential as a therapeutic target. Here, we constructed an anti-CD19-N-(4-carboxycyclohexylmethyl) maleimide N-hydroxysuccinimide ester (SMCC)-protamine (CSP)-STAT3 small interfering RNA (siRNA) conjugate and demonstrated that the CSP-STAT3 siRNA conjugate could specifically bind to normal B cells and A20 lymphoma cells in vitro. It decreased the STAT3 expression in B cell lymphoma cell lines (A20, SU-DHL-2 and OCI-Ly3), resulting in reduced proliferation of lymphoma cells featured with lower S-phase and higher apoptosis. Using an A20 transplantable lymphoma model, we found that the CSP-STAT3 siRNA conjugate significantly inhibited tumor growth and weight. Ki-67, p-STAT3, STAT3, and serum IL-6 levels were all significantly reduced in A20-bearing mice treated with CSP-STAT3 siRNA. These findings indicate that specifically targeting STAT3 siRNA to B cell lymphoma cell lines can significantly decrease STAT3 activity and inhibit tumor progression in vitro and in vivo, suggesting its potential utilization for cancer treatment.

Microbial metabolite restricts 5-fluorouracil-resistant colonic tumor progression by sensitizing drug transporters via regulation of FOXO3-FOXM1 axis.

The survival rate of colorectal cancer patients is adversely affected by the selection of tumors resistant to conventional anti-cancer drugs such as 5-fluorouracil (5FU). Although there is mounting evidence that commensal gut microbiota is essential for effective colon cancer treatment, the detailed molecular mechanisms and the role of gut microbial metabolites remain elusive. The goal of this study is to decipher the impact and mechanisms of gut microbial metabolite, urolithin A (UroA) and its structural analogue, UAS03 on reversal of 5FU-resistant (5FUR) colon cancers. Methods: We have utilized the SW480 and HCT-116 parental (5FU-sensitive) and 5FUR colon cancer cells to examine the chemosensitization effects of UroA or UAS03 by using both in vitro and in vivo models. The effects of mono (UroA/UAS03/5FU) and combinatorial therapy (UroA/UAS03 + 5FU) on cell proliferation, apoptosis, cell migration and invasion, regulation of epithelial mesenchymal transition (EMT) mediators, expression and activities of drug transporters, and their regulatory transcription factors were examined using molecular, cellular, immunological and flowcytometric methods. Further, the anti-tumor effects of mono/combination therapy (UroA or UAS03 or 5FU or UroA/UAS03 + 5FU) were examined using pre-clinical models of 5FUR-tumor xenografts in NRGS mice and azoxymethane (AOM)-dextran sodium sulfate (DSS)-induced colon tumors. Results: Our data showed that UroA or UAS03 in combination with 5FU significantly inhibited cell viability, proliferation, invasiveness as well as induced apoptosis of the 5FUR colon cancer cells compared to mono treatments. Mechanistically, UroA or UAS03 chemosensitized the 5FUR cancer cells by downregulating the expression and activities of drug transporters (MDR1, BCRP, MRP2 and MRP7) leading to a decrease in the efflux of 5FU. Further, our data suggested the UroA or UAS03 chemosensitized 5FUR cancer cells to 5FU treatment through regulating FOXO3-FOXM1 axis. Oral treatment with UroA or UAS03 in combination with low dose i.p. 5FU significantly reduced the growth of 5FUR-tumor xenografts in NRGS mice. Further, combination therapy significantly abrogated colonic tumors in AOM-DSS-induced colon tumors in mice. Conclusions: In summary, gut microbial metabolite UroA and its structural analogue UAS03 chemosensitized the 5FUR colon cancers for effective 5FU chemotherapy. This study provided the novel characteristics of gut microbial metabolites to have significant translational implications in drug-resistant cancer therapeutics.

Impact of glycoengineering and antidrug antibodies on the anticancer activity of a plant-made lectin-Fc fusion protein.

Plants are an efficient production platform for manufacturing glycoengineered monoclonal antibodies and antibody-like molecules. Avaren-Fc (AvFc) is a lectin-Fc fusion protein or lectibody produced in Nicotiana benthamiana, which selectively recognizes cancer-associated high-mannose glycans. In this study, we report the generation of a glycovariant of AvFc that is devoid of plant glycans, including the core α1,3-fucose and ß1,2-xylose residues. The successful removal of these glycans was confirmed by glycan analysis using HPLC. This variant, AvFcΔXF , has significantly higher affinity for Fc gamma receptors and induces higher levels of luciferase expression in an antibody-dependent cell-mediated cytotoxicity (ADCC) reporter assay against B16F10 murine melanoma cells without inducing apoptosis or inhibiting proliferation. In the B16F10 flank tumour mouse model, we found that systemic administration of AvFcΔXF , but not an aglycosylated AvFc variant lacking affinity for Fc receptors, significantly delayed the growth of tumours, suggesting that Fc-mediated effector functions were integral. AvFcΔXF treatment also significantly reduced lung metastasis of B16F10 upon intravenous challenge whereas a sugar-binding-deficient mutant failed to show efficacy. Lastly, we determined the impact of antidrug antibodies (ADAs) on drug activity in vivo by pretreating animals with AvFcΔXF before implanting tumours. Despite a significant ADA response induced by the pretreatment, we found that the activity of AvFcΔXF was unaffected by the presence of these antibodies. These results demonstrate that glycoengineering is a powerful strategy to enhance AvFc's antitumor activity.

Alcohol-driven metabolic reprogramming promotes development of RORγt-deficient thymic lymphoma.

RORγt is a master regulator of Th17 cells. Despite evidence linking RORγt deficiency/inhibition with metastatic thymic T cell lymphomas, the role of RORγt in lymphoma metabolism is unknown. Chronic alcohol consumption plays a causal role in many human cancers. The risk of T cell lymphoma remains unclear in humans with alcohol use disorders (AUD) after chronic RORγt inhibition. Here we demonstrated that alcohol consumption accelerates RORγt deficiency-induced lymphomagenesis. Loss of RORγt signaling in the thymus promotes aerobic glycolysis and glutaminolysis and increases allocation of glutamine carbon into lipids. Importantly, alcohol consumption results in a shift from aerobic glycolysis to glutaminolysis. Both RORγt deficiency- and alcohol-induced metabolic alterations are mediated by c-Myc, as silencing of c-Myc decreases the effects of alcohol consumption and RORγt deficiency on glutaminolysis, biosynthesis, and tumor growth in vivo. The ethanol-mediated c-Myc activation coupled with increased glutaminolysis underscore the critical role of RORγt-Myc signaling and translation in lymphoma.

The induction of peripheral trained immunity in the pancreas incites anti-tumor activity to control pancreatic cancer progression.

Despite the remarkable success of immunotherapy in many types of cancer, pancreatic ductal adenocarcinoma has yet to benefit. Innate immune cells are critical to anti-tumor immunosurveillance and recent studies have revealed that these populations possess a form of memory, termed trained innate immunity, which occurs through transcriptomic, epigenetic, and metabolic reprograming. Here we demonstrate that yeast-derived particulate ß-glucan, an inducer of trained immunity, traffics to the pancreas, which causes a CCR2-dependent influx of monocytes/macrophages to the pancreas that display features of trained immunity. These cells can be activated upon exposure to tumor cells and tumor-derived factors, and show enhanced cytotoxicity against pancreatic tumor cells. In orthotopic models of pancreatic ductal adenocarcinoma, ß-glucan treated mice show significantly reduced tumor burden and prolonged survival, which is further enhanced when combined with immunotherapy. These findings characterize the dynamic mechanisms and localization of peripheral trained immunity and identify an application of trained immunity to cancer.

Tumor-derived exosomes drive immunosuppressive macrophages in a pre-metastatic niche through glycolytic dominant metabolic reprogramming.

One of the defining characteristics of a pre-metastatic niche, a fundamental requirement for primary tumor metastasis, is infiltration of immunosuppressive macrophages. How these macrophages acquire their phenotype remains largely unexplored. Here, we demonstrate that tumor-derived exosomes (TDEs) polarize macrophages toward an immunosuppressive phenotype characterized by increased PD-L1 expression through NF-kB-dependent, glycolytic-dominant metabolic reprogramming. TDE signaling through TLR2 and NF-κB leads to increased glucose uptake. TDEs also stimulate elevated NOS2, which inhibits mitochondrial oxidative phosphorylation resulting in increased conversion of pyruvate to lactate. Lactate feeds back on NF-κB, further increasing PD-L1. Analysis of metastasis-negative lymph nodes of non-small-cell lung cancer patients revealed that macrophage PD-L1 positively correlates with levels of GLUT-1 and vesicle release gene YKT6 from primary tumors. Collectively, our study provides a novel mechanism by which macrophages within a pre-metastatic niche acquire their immunosuppressive phenotype and identifies an important link among exosomes, metabolism, and metastasis.

89Zr-Labeled Anti-PD-L1 Antibody Fragment for Evaluating In Vivo PD-L1 Levels in Melanoma Mouse Model.

The rise of programmed death-1 (PD-1)/PD-L1 immune checkpoint inhibitor therapy has been one of the most promising developments in melanoma research. However, not all the melanoma patients respond to such immune checkpoint blockade. There is a great need of biomarkers for appropriate melanoma patient selection and therapeutic efficacy monitoring. The objective of this study is to develop a novel radiolabeled anti-PD-L1 antibody fragment, as an imaging biomarker, for evaluating the in vivo PD-L1 levels in melanoma. The Df-conjugated F(ab')2 fragment of the anti-mouse PD-L1 antibody was successfully synthesized and radiolabeled with 89Zr. Both Df-F(ab')2 and 89Zr-Df-F(ab')2 maintained the nano-molar murine PD-L1 targeting specificity and affinity. 89Zr-Df-F(ab')2 showed less uptake in normal liver tissue in mice compared with its full antibody counterpart 89Zr-Df-anti-PD-L1. Positron emission tomography (PET)/computed tomography images clearly showed that 89Zr-Df-F(ab')2 possessed superior pharmacokinetics and imaging contrast over the radiolabeled full antibody, with much earlier and higher tumor uptake (5.5 times more at 2 h post injection) and much lower liver background (51% reduction at 2 h post injection). The specific and high murine PD-L1-targeting uptake at tumor foci coupled with fast clearance of 89Zr-Df-F(ab')2 highlighted its potential for in vivo PET imaging of murine PD-L1 levels and future development of radiolabeled anti-human PD-L1 fragment for potential application in melanoma patients.

Effect of the stop-flow technique on cardiac retention of c-kit positive human cardiac stem cells after intracoronary infusion in a porcine model of chronic ischemic cardiomyopathy.

It is commonly thought that the optimal method for intracoronary administration of cells is to stop coronary flow during cell infusion, in order to prolong cell/vascular wall contact, enhance adhesion, and promote extravasation of cells into the interstitial space. However, occlusion of a coronary artery with a balloon involves serious risks of vascular damage and/or dissection, particularly in non-stented segments such as those commonly found in patients with heart failure. It remains unknown whether the use of the stop-flow technique results in improved donor cell retention. Acute myocardial infarction was produced in 14 pigs. One to two months later, pigs received 10 million indium-111 oxyquinoline (oxine)-labeled c-kit(pos) human cardiac stem cells (hCSCs) via intracoronary infusion with (n = 7) or without (n = 7) balloon inflation. Pigs received cyclosporine to prevent acute graft rejection. Animals were euthanized 24 h later and hearts harvested for radioactivity measurements. With the stop-flow technique, the retention of hCSCs at 24 h was 5.41 ± 0.80 % of the injected dose (n = 7), compared with 4.87 ± 0.62 % without coronary occlusion (n = 7), (P = 0.60). When cells are delivered intracoronarily in a clinically relevant porcine model of chronic ischemic cardiomyopathy, the use of the stop-flow technique does not result in greater myocardial cell retention at 24 h compared with non-occlusive infusion. These results have practical implications for the design of cell therapy trials. Our observations suggest that the increased risk of complications secondary to coronary manipulation and occlusion is not warranted.

Enterobacteria-secreted particles induce production of exosome-like S1P-containing particles by intestinal epithelium to drive Th17-mediated tumorigenesis.

Gut-associated inflammation plays a crucial role in the progression of colon cancer. Here, we identify a novel pathogen-host interaction that promotes gut inflammation and the development of colon cancer. We find that enteropathogenic bacteria-secreted particles (ET-BSPs) stimulate intestinal epithelium to produce IDENs (intestinal mucosa-derived exosome-like nanoparticles) containing elevated levels of sphingosine-1-phosphate, CCL20 and prostaglandin E2 (PGE2). CCL20 and PGE2 are required for the recruitment and proliferation, respectively, of Th17 cells, and these processes also involve the MyD88-mediated pathway. By influencing the recruitment and proliferation of Th17 cells in the intestine, IDENs promote colon cancer. We demonstrate the biological effect of sphingosine-1-phosphate contained in IDENs on tumour growth in spontaneous and transplanted colon cancer mouse models. These findings provide deeper insights into how host-microbe relationships are mediated by particles secreted from both bacterial and host cells.

Introduction of an 8-aminooctanoic acid linker enhances uptake of 99mTc-labeled lactam bridge-cyclized α-MSH peptide in melanoma.

UNLABELLED: The purpose of this study was to examine the effects of amino acid, hydrocarbon, and polyethylene glycol (PEG) linkers on the melanoma targeting and imaging properties of (99m)Tc-labeled lactam bridge-cyclized HYNIC-linker-Nle-CycMSHhex (hydrazinonicotinamide-linker-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2) peptides. METHODS: Four novel peptides (HYNIC-GGGNle-CycMSHhex, HYNIC-GSGNle-CycMSHhex, HYNIC-PEG2Nle-CycMSHhex, and HYNIC-AocNle-CycMSHhex) were designed and synthesized. The melanocortin-1 receptor binding affinities of the peptides were determined in B16/F1 melanoma cells. The biodistribution of (99m)Tc(ethylenediaminediacetic acid [EDDA])-HYNIC-GGGNle-CycMSHhex, (99m)Tc(EDDA)-HYNIC-GSGNle-CycMSHhex, (99m)Tc(EDDA)-HYNIC-PEG2Nle-CycMSHhex, and (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex were determined in B16/F1 melanoma-bearing C57 mice at 2 h after injection to select a lead peptide for further evaluation. The melanoma targeting and imaging properties of (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex were further examined because of its high melanoma uptake. RESULTS: The inhibitory concentrations of 50% (IC50) for HYNIC-GGGNle-CycMSHhex, HYNIC-GSGNle-CycMSHhex, HYNIC-PEG2Nle-CycMSHhex, and HYNIC-AocNle-CycMSHhex were 0.7 ± 0.1, 0.8 ± 0.09, 0.4 ± 0.08, and 0.3 ± 0.06 nM, respectively, in B16/F1 melanoma cells. Among these four (99m)Tc-labeled peptides, (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex displayed the highest melanoma uptake (22.3 ± 1.72 percentage injected dose/g) at 2 h after injection. (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex exhibited high tumor-to-normal-organ uptake ratios except for the kidneys. The tumor-to-kidney uptake ratios of (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex were 3.29, 3.63, and 6.78 at 2, 4, and 24 h, respectively, after injection. The melanoma lesions were clearly visualized by SPECT/CT using (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex as an imaging probe at 2 h after injection. CONCLUSION: High melanoma uptake and fast urinary clearance of (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex highlighted its potential for metastatic melanoma detection in the future.

Targeted drug delivery to intestinal macrophages by bioactive nanovesicles released from grapefruit.

The gut mucosal immune system is considered to play an important role in counteracting potential adverse effects of food-derived antigens including nanovesicles. Whether nanovesicles naturally released from edible fruit work in a coordinated manner with gut immune cells to maintain the gut in a noninflammatory status is not known. Here, as proof of concept, we demonstrate that grapefruit-derived nanovesicles (GDNs) are selectively taken up by intestinal macrophages and ameliorate dextran sulfate sodium (DSS)-induced mouse colitis. These effects were mediated by upregulating the expression of heme oxygenase-1 (HO-1) and inhibiting the production of IL-1ß and TNF-α in intestinal macrophages. The inherent biocompatibility and biodegradability, stability at wide ranges of pH values, and targeting of intestinal macrophages led us to further develop a novel GDN-based oral delivery system. Incorporating methotrexate (MTX), an anti-inflammatory drug, into GDNs and delivering the MTX-GDNs to mice significantly lowered the MTX toxicity when compared with free MTX, and remarkably increased its therapeutic effects in DSS-induced mouse colitis. These findings demonstrate that GDNs can serve as immune modulators in the intestine, maintain intestinal macrophage homeostasis, and can be developed for oral delivery of small molecule drugs to attenuate inflammatory responses in human disease.

Influences of hydrocarbon linkers on the receptor binding affinities of gonadotropin-releasing hormone peptides.

Three new DOTA-conjugated GnRH peptides with various hydrocarbon linkers were synthesized to evaluate the influences of the linkers on their receptor binding affinities. The hydrocarbon linker displayed a profound impact on the receptor binding affinities of DOTA-conjugated GnRH peptides. The Aun linker was better than Gaba, Ahx and Aoc linkers in retaining strong receptor binding affinity of the GnRH peptide. DOTA-Aun-(D-Lys(6)-GnRH) displayed 22.8 nM GnRH receptor binding affinity. (111)In-DOTA-Aun-(D-Lys(6)-GnRH) exhibited fast tumor uptake and urinary clearance in MDA-MB-231 human breast cancer-xenografted nude mice. The cellular and biological results provided an insight into the design of new GnRH peptides in the future.

Melanoma targeting property of a Lu-177-labeled lactam bridge-cyclized alpha-MSH peptide.

The purpose of this study was to determine the melanoma targeting property of (177)Lu-DOTA-GGNle-CycMSHhex in B16/F1 melanoma-bearing C57 mice. (177)Lu-DOTA-GGNle-CycMSHhex exhibited high receptor-mediated melanoma uptake and fast urinary clearance. The tumor uptake of (177)Lu-DOTA-GGNle-CycMSHhex was 20.25 ± 4.59 and 21.63 ± 6.27% ID/g at 0.5 and 2h post-injection, respectively. Approximately 83% of injected dose cleared out the body via urinary system at 2h post-injection. (177)Lu-DOTA-GGNle-CycMSHhex showed high tumor to normal organ uptake ratios except for the kidneys. The tumor/kidney uptake ratios of (177)Lu-DOTA-GGNle-CycMSHhex were 2.76 and 1.74 at 2 and 24h post-injection. The melanoma lesions were clearly visualized by SPECT/CT using (177)Lu-DOTA-GGNle-CycMSHhex as an imaging probe at 2h post-injection. Overall, high melanoma uptake coupled with fast urinary clearance of (177)Lu-DOTA-GGNle-CycMSHhex underscored its potential for melanoma treatment in the future.

Design and evaluation of new Tc-99m-labeled lactam bridge-cyclized alpha-MSH peptides for melanoma imaging.

The purpose of this study was to examine the melanoma targeting and imaging properties of new (99m)Tc-labeled lactam bridge-cyclized alpha-melanocyte stimulating hormone (α-MSH) peptides using bifunctional chelating agents. MAG3-GGNle-CycMSH(hex), AcCG3-GGNle-CycMSH(hex), and HYNIC-GGNle-CycMSH(hex) peptides were synthesized, and their melanocortin-1 (MC1) receptor binding affinities were determined in B16/F1 melanoma cells. The biodistribution of (99m)Tc-MAG3-GGNle-CycMSH(hex), (99m)Tc-AcCG3-GGNle-CycMSH(hex), (99m)Tc(CO)3-HYNIC-GGNle-CycMSH(hex), and (99m)Tc(EDDA)-HYNIC-GGNle-CycMSH(hex) were determined in B16/F1 melanoma-bearing C57 mice at 2 h postinjection to select a lead peptide for further evaluation. The melanoma targeting and imaging properties of (99m)Tc(EDDA)-HYNIC-GGNle-CycMSH(hex) were further examined because of its high melanoma uptake and fast urinary clearance. The IC50 values of MAG3-GGNle-CycMSH(hex), AcCG3-GGNle-CycMSH(hex), and HYNIC-GGNle-CycMSH(hex) were 1.0 ± 0.05, 1.2 ± 0.19, and 0.6 ± 0.04 nM in B16/F1 melanoma cells, respectively. Among these four (99m)Tc-peptides, (99m)Tc(EDDA)-HYNIC-GGNle-CycMSH(hex) exhibited the highest melanoma uptake (14.14 ± 4.90% ID/g) and fastest urinary clearance (91.26 ± 1.96% ID) at 2 h postinjection. (99m)Tc(EDDA)-HYNIC-GGNle-CycMSH(hex) showed high tumor to normal organ uptake ratios except for the kidneys. The tumor/kidney uptake ratios of (99m)Tc(EDDA)-HYNIC-GGNle-CycMSH(hex) were 2.50 and 3.55 at 4 and 24 h postinjection. The melanoma lesions were clearly visualized by SPECT/CT using (99m)Tc(EDDA)-HYNIC-GGNle-CycMSH(hex) as an imaging probe at 2 h postinjection. Overall, high melanoma uptake coupled with fast urinary clearance of (99m)Tc(EDDA)-HYNIC-GGNle-CycMSH(hex) highlighted its potential for metastatic melanoma detection in the future.

Cu-64-labeled lactam bridge-cyclized α-MSH peptides for PET imaging of melanoma.

The purpose of this study was to examine and compare the melanoma targeting and imaging properties of (64)Cu-NOTA-GGNle-CycMSH(hex) {(64)Cu-1,4,7-triazacyclononane-1,4,7-triacetic acid-Gly-Gly-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2} and (64)Cu-DOTA-GGNle-CycMSH(hex) {(64)Cu-1,4,7,10-tetraazacyclononane-1,4,7,10-tetraacetic acid-GGNle-CycMSH(hex)}. Two lactam bridge-cyclized peptides, NOTA-GGNle-CycMSH(hex) and DOTA-GGNle-CycMSH(hex), were synthesized using fluorenylmethyloxy carbonyl (Fmoc) chemistry. The melanocortin-1 (MC1) receptor binding affinity of NOTA-GGNle-CycMSH(hex) was determined in B16/F1 melanoma cells and compared with DOTA-GGNle-CycMSH(hex). The melanoma targeting and imaging properties of (64)Cu-NOTA-GGNle-CycMSH(hex) and (64)Cu-DOTA-GGNle-CycMSH(hex) were determined in B16/F1 melanoma-bearing C57 mice. NOTA-GGNle-CycMSH(hex) and DOTA-GGNle-CycMSH(hex) displayed comparable MC1 receptor binding affinities (1.6 vs 2.1 nM). The substitution of DOTA with NOTA dramatically increased the melanoma uptake and decreased the renal and liver uptake of (64)Cu-NOTA-GGNle-CycMSH(hex). The tumor uptake of (64)Cu-NOTA-GGNle-CycMSH(hex) was between 12.39 ± 1.61 and 12.71 ± 2.68% ID/g at 0.5, 2, and 4 h postinjection. The accumulation of (64)Cu-NOTA-GGNle-CycMSH(hex) activity in normal organs was lower than 1.02% ID/g except for the kidneys 2, 4, and 24 h postinjection. The tumor/liver uptake ratios of (64)Cu-NOTA-GGNle-CycMSHhex were 17.96, 16.95, and 8.02, whereas the tumor/kidney uptake ratios of (64)Cu-NOTA-GGNle-CycMSH(hex) were 2.52, 3.60, and 5.74 at 2, 4, and 24 h postinjection, respectively. Greater than 91% of the injected radioactivity cleared through the urinary system by 2 h postinjection. The substitution of DOTA with NOTA resulted in a dramatic increase in melanoma uptake and decrease in renal and liver uptake of (64)Cu-NOTA-GGNle-CycMSH(hex) as compared to (64)Cu-DOTA-GGNle-CycMSH(hex). High melanoma uptake coupled with low accumulation in nontarget organs suggested (64)Cu-NOTA-GGNle-CycMSH(hex) as a lead radiolabeled peptide for melanoma imaging and therapy.

Gallium-67-labeled lactam bridge-cyclized alpha-MSH peptides with enhanced melanoma uptake and reduced renal uptake.

The purpose of this study was to examine the melanoma targeting and pharmacokinetic properties of (67)Ga-DOTA-GGNle-CycMSHhex {(67)Ga-1,4,7,10-tetraazacyclononane-1,4,7,10-tetraacetic acid-Gly-Gly-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2} and (67)Ga-NOTA-GGNle-CycMSHhex {(67)Ga-1,4,7-triazacyclononane-1,4,7-triacetic acid-Gly-Gly-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2} and compare with (67)Ga-DOTA-GlyGlu-CycMSH {(67)Ga-DOTA-Gly-Glu-c[Lys-Nle-Glu-His-DPhe-Arg-Trp-Gly-Arg-Pro-Val-Asp]} we previously reported. DOTA-GGNle-CycMSHhex and NOTA-GGNle-CycMSHhex were synthesized using fluorenylmethyloxy carbonyl (Fmoc) chemistry. The melanocortin-1 (MC1) receptor binding affinity of NOTA-GGNle-CycMSHhex was determined in B16/F1 melanoma cells and compared with DOTA-GGNle-CycMSHhex. The melanoma targeting and pharmacokinetic properties of (67)Ga-NOTA-GGNle-CycMSHhex and (67)Ga-DOTA-GGNle-CycMSHhex were determined in B16/F1 melanoma-bearing C57 mice. NOTA-GGNle-CycMSHhex and DOTA-GGNle-CycMSHhex displayed comparable MC1 receptor binding affinities (1.6 vs 2.1 nM) in B16/F1 melanoma cells. Both (67)Ga-NOTA-GGNle-CycMSHhex and (67)Ga-DOTA-GGNle-CycMSHhex exhibited dramatically enhanced melanoma uptake and reduced renal uptake than (67)Ga-DOTA-GlyGlu-CycMSH in B16/F1 melanoma-bearing C57 mice. Furthermore, (67)Ga-NOTA-GGNle-CycMSHhex exhibited more favorable radiolabeling conditions (>85% radiolabeling yields started at 37 °C), as well as higher tumor/kidney uptake ratios than (67)Ga-DOTA-GGNle-CycMSHhex at 0.5, 2, and 24 h postinjection. High melanoma uptake coupled with low renal uptake highlighted the potential of (67)Ga-NOTA-GGNle-CycMSHhex for melanoma imaging and therapy.

A novel indium-111-labeled gonadotropin-releasing hormone peptide for human prostate cancer imaging.

The purpose of this study was to evaluate the tumor targeting and imaging properties of a novel (111)In-labeled gonadotropin-releasing hormone (GnRH) peptide {1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-Ahx-(D-Lys(6)-GnRH1)} for human prostate cancer. The biodistribution and tumor imaging properties of (111)In-DOTA-Ahx-(D-Lys(6)-GnRH1) were determined in DU145 human prostate cancer-xenografted nude mice. (111)In-DOTA-Ahx-(d-Lys(6)-GnRH1) exhibited rapid tumor uptake (1.27 ± 0.40% ID/g at 0.5h post-injection) coupled with fast whole-body clearance through the urinary system. The DU145 human prostate cancer-xenografted tumor lesions were clearly visualized by single photon emission computed tomography (SPECT)/CT at 0.5h post-injection of (111)In-DOTA-Ahx-(D-Lys(6)-GnRH1). The successful imaging of DU145 human prostate cancer-xenografted tumor lesions using (111)In-DOTA-Ahx-(d-Lys(6)-GnRH1) highlighted its potential as a novel imaging probe for human prostate cancer imaging.

Synthesis and evaluation of novel gonadotropin-releasing hormone receptor-targeting peptides.

The purpose of this study was to develop novel radiolabeled gonadotropin-releasing hormone (GnRH) receptor-targeting peptides for breast cancer imaging. Three novel 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-conjugated GnRH peptides were designed and synthesized. The radiometal chelator DOTA was conjugated to the epsilon or alpha amino group of D-lysine, or the epsilon amino group of L-lysine via an Ahx {aminohexanoic acid} linker to generate DOTA-Ahx-(D-Lys(6)-GnRH1), DOTA-Ahx-(D-Lys(6)-GnRH2) and DOTA-Ahx-(L-Lys(6)-GnRH3), respectively. The conjugation of the DOTA to the epsilon amino group of D-lysine (rather than alpha amino group of D-lysine nor epsilon amino group of L-lysine) maintained the nanomolar GnRH receptor binding affinity. The IC(50) values of DOTA-Ahx-(D-Lys(6)-GnRH1), DOTA-Ahx-(D-Lys(6)-GnRH2) and DOTA-Ahx-(L-Lys(6)-GnRH3) were 36.1 nM, 10.6 mM and 4.3 mM, respectively. Since only DOTA-Ahx-(D-Lys(6)-GnRH1) displayed nanomolar receptor binding affinity, the specific GnRH receptor binding of (111)In-DOTA-Ahx-(D-Lys(6)-GnRH1) was determined in human GnRH receptor membrane preparations. Furthermore, the biodistribution and tumor imaging properties of (111)In-DOTA-Ahx-(D-Lys(6)-GnRH1) were examined in MDA-MB-231 human breast cancer-xenografted nude mice. (111)In-DOTA-Ahx-(D-Lys(6)-GnRH1) exhibited specific GnRH receptor binding and rapid tumor uptake (1.76 ± 0.58% ID/g at 0.5 h postinjection) coupled with fast whole-body clearance through the urinary system. The MDA-MB-231 human breast cancer-xenografted tumor lesions were clearly visualized by single photon emission computed tomography (SPECT)/CT at 1 h postinjection of (111)In-DOTA-Ahx-(D-Lys(6)-GnRH1). The profound impact of DOTA position on the binding affinity of the GnRH peptide provided a new insight into the design of novel radiolabeled GnRH peptides. The successful imaging of MDA-MB-231 human breast cancer-xenografted tumor lesions using (111)In-DOTA-Ahx-(D-Lys(6)-GnRH1) suggested its potential as a novel imaging probe for human breast cancer imaging.

Effects of the amino acid linkers on the melanoma-targeting and pharmacokinetic properties of 111In-labeled lactam bridge-cyclized alpha-MSH peptides.

UNLABELLED: The purpose of this study was to examine the profound effects of the amino acid linkers on the melanoma-targeting and pharmacokinetic properties of (111)In-labeled lactam bridge-cyclized DOTA-[X]-CycMSH(hex) {1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-[X]-c[Asp-His-dPhe-Arg-Trp-Lys]-CONH(2); X = GGNle, GENle, or NleGE; GG = -Gly-Gly- and GE = -Gly-Glu-} peptides. METHODS: Three novel peptides (DOTA-GGNle-CycMSH(hex), DOTA-GENle-CycMSH(hex), and DOTA-NleGE-CycMSH(hex)) were designed and synthesized. The melanocortin-1 (MC1) receptor-binding affinities of the peptides were determined in B16/F1 melanoma cells. The melanoma-targeting and pharmacokinetic properties of (111)In-DOTA-GGNle-CycMSH(hex) and (111)In-DOTA-GENle-CycMSH(hex) were determined in B16/F1 melanoma-bearing C57 mice. RESULTS: DOTA-GGNle-CycMSH(hex) and DOTA-GENle-CycMSH(hex) displayed 2.1 and 11.5 nM MC1 receptor-binding affinities, whereas DOTA-NleGE-CycMSH(hex) showed 873.4 nM MC1 receptor-binding affinity. The introduction of the -GG- linker maintained high melanoma uptake while decreasing kidney and liver uptake of (111)In-DOTA-GGNle-CycMSH(hex). The tumor uptake of (111)In-DOTA-GGNle-CycMSH(hex) was 19.05 ± 5.04 and 18.6 ± 3.56 percentage injected dose per gram at 2 and 4 h after injection, respectively. (111)In-DOTA-GGNle-CycMSH(hex) exhibited 28%, 32%, and 42% less kidney uptake than (111)In-DOTA-Nle-CycMSH(hex) we reported previously, and 61%, 65%, and 68% less liver uptake than (111)In-DOTA-Nle-CycMSH(hex) at 2, 4, and 24 h after injection, respectively. CONCLUSION: The amino acid linkers exhibited profound effects on the melanoma-targeting and pharmacokinetic properties of the (111)In-labeled lactam bridge-cyclized α-melanocyte-stimulating hormone peptides. Introduction of the -GG- linker maintained high melanoma uptake while reducing kidney and liver uptake of (111)In-DOTA-GGNle-CycMSH(hex), highlighting its potential as an effective imaging probe for melanoma detection, as well as a therapeutic peptide for melanoma treatment when labeled with a therapeutic radionuclide.