Brown adipose tissue metabolism in women is dependent on ovarian status.

In rodents, loss of estradiol (E2) reduces brown adipose tissue (BAT) metabolic activity. Whether E2 impacts BAT activity in women is not known. BAT oxidative metabolism was measured in premenopausal (n = 27; 35 ± 9 yr; body mass index = 26.0 ± 5.3 kg/m2) and postmenopausal (n = 25; 51 ± 8 yr; body mass index = 28.0 ± 5.0 kg/m2) women at room temperature and during acute cold exposure using [11C]acetate with positron emission tomography coupled with computed tomograph. BAT glucose uptake was also measured during acute cold exposure using 2-deoxy-2-[18F]fluoro-d-glucose. To isolate the effects of ovarian hormones from biological aging, measurements were repeated in a subset of premenopausal women (n = 8; 40 ± 4 yr; BMI = 28.0 ± 7.2 kg/m2) after 6 mo of gonadotropin-releasing hormone agonist therapy to suppress ovarian hormones. At room temperature, there was no difference in BAT oxidative metabolism between premenopausal (0.56 ± 0.31 min-1) and postmenopausal women (0.63 ± 0.28 min-1). During cold exposure, BAT oxidative metabolism (1.28 ± 0.85 vs. 0.91 ± 0.63 min-1, P = 0.03) and net BAT glucose uptake (84.4 ± 82.5 vs. 29.7 ± 31.4 nmol·g-1·min-1, P < 0.01) were higher in premenopausal than postmenopausal women. In premenopausal women who underwent gonadotropin-releasing hormone agonist, cold-stimulated BAT oxidative metabolism was reduced to a similar level (from 1.36 ± 0.66 min-1 to 0.91 ± 0.41 min-1) to that observed in postmenopausal women (0.91 ± 0.63 min-1). These results provide the first evidence in humans that reproductive hormones are associated with BAT oxidative metabolism and suggest that BAT may be a target to attenuate age-related reduction in energy expenditure and maintain metabolic health in postmenopausal women.NEW & NOTEWORTHY In rodents, loss of estrogen reduces brown adipose tissue (BAT) activity. Whether this is true in humans is not known. We found that BAT oxidative metabolism and glucose uptake were lower in postmenopausal compared to premenopausal women. In premenopausal women who underwent ovarian suppression to reduce circulating estrogen, BAT oxidative metabolism was reduced to postmenopausal levels. Thus the loss of ovarian function in women leads to a reduction in BAT metabolic activity independent of age.

Effect of Ibuprofen as an Albumin Binder on Melanoma-Targeting Properties of 177Lu-Labeled Ibuprofen-Conjugated Alpha-Melanocyte-Stimulating Hormone Peptides.

The purpose of this study was to examine how the introduction of ibuprofen (IBU) affected tumor-targeting and biodistribution properties of 177Lu-labeled IBU-conjugated alpha-melanocyte-stimulating hormone peptides. The IBU was used as an albumin binder and conjugated to the DOTA-Lys moiety without or with a linker to yield DOTA-Lys(IBU)-GG-Nle-CycMSHhex {1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-Lys(IBU)-Gly-Gly-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2}, DOTA-Lys(Asp-IBU)-GGNle-CycMSHhex, DOTA-Lys(Asn-IBU)-GGNle-CycMSHhex, and DOTA-Lys(Dab-IBU)-GGNle-CycMSHhex peptides. Their melanocortin-receptor 1 (MC1R) binding affinities were determined on B16/F10 melanoma cells first. Then the biodistribution of 177Lu-labeled peptides was determined on B16/F10 melanoma-bearing C57 mice at 2 h postinjection to choose the lead peptide for further examination. The full biodistribution and melanoma imaging properties of 177Lu-DOTA-Lys(Asp-IBU)-GGNle-CycMSHhex were further evaluated using B16/F10 melanoma-bearing C57 mice. DOTA-Lys(IBU)-GG-Nle-CycMSHhex, DOTA-Lys(Asp-IBU)-GGNle-CycMSHhex, DOTA-Lys(Asn-IBU)-GGNle-CycMSHhex, and DOTA-Lys(Dab-IBU)-GGNle-CycMSHhex displayed the IC50 values of 1.41 ± 0.37, 1.52 ± 0.08, 0.03 ± 0.01, and 0.58 ± 0.06 nM on B16/F10 melanoma cells, respectively. 177Lu-DOTA-Lys(Asp-IBU)-GGNle-CycMSHhex exhibited the lowest liver and kidney uptake among all four designed 177Lu peptides. Therefore, 177Lu-DOTA-Lys(Asp-IBU)-GGNle-CycMSHhex was further evaluated for its full biodistribution and melanoma imaging properties. The B16/F10 melanoma uptake of 177Lu-DOTA-Lys(Asp-IBU)-GGNle-CycMSHhex was 19.5 ± 3.12, 24.12 ± 3.35, 23.85 ± 2.08, and 10.80 ± 2.89% ID/g at 0.5, 2, 4, and 24 h postinjection, respectively. Moreover, 177Lu-DOTA-Lys(Asp-IBU)-GGNle-CycMSHhex could clearly visualize the B16/F10 melanoma lesions at 2 h postinjection. The conjugation of IBU with or without a linker to GGNle-CycMSHhex affected the MC1R binding affinities of the designed peptides. The charge of the linker played a key role in the liver and kidney uptake of 177Lu-Asp-IBU, 177Lu-Asn-IBU, and 177Lu-Dab-IBU. 177Lu-Asp-IBU exhibited higher tumor/liver and tumor/kidney uptake ratios than those of 177Lu-Asn-IBU and 177Lu-Dab-IBU, underscoring its potential evaluation for melanoma therapy in the future.

Effects of Polyethylene Glycol and 8-Aminooctanoic Acid Linkers on Melanoma Uptake of [99mTc]Tc-Tricarbonyl-NOTA-Conjugated Lactam-Cyclized α-MSH Peptides.

The purpose of this study was to evaluate the effect of linkers on tumor targeting and biodistribution of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex {[99mTc]Tc(CO)3-1,4,7-triazacyclononane-1,4,7-triyl-triacetic acid-polyethylene glycol-Nle-c[Asp-His-d-Phe-Arg-Trp-Lys]-CONH2} and [99mTc]Tc(CO)3-NOTA-AocNle-CycMSHhex {[99mTc]Tc(CO)3-NOTA-8-aminooctanoic acid-Nle-CycMSHhex} on B16/F10 melanoma-bearing mice. NOTA-PEG2Nle-CycMSHhex and NOTA-AocNle-CycMSHhex were synthesized and radiolabeled with [99mTc]Tc via the {[99mTc]Tc(CO)3(OH2)3}+ intermediate. The biodistribution of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex and [99mTc]Tc(CO)3-NOTA-AocNle-CycMSHhex was determined on B16/F10 melanoma-bearing C57 mice. The melanoma imaging property of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex was determined on B16/F10 melanoma-bearing C57 mice. [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex and [99mTc]Tc(CO)3-NOTA-AocNle-CycMSHhex were readily prepared with more than 90% radiochemical yields and exhibited MC1R-specific binding on B16/F10 melanoma cells. [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex exhibited a higher tumor uptake than [99mTc]Tc(CO)3-NOTA-AocNle-CycMSHhex at 2, 4, and 24 h postinjection. The tumor uptake of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex was 13.63 ± 1.13, 31.93 ± 2.57, 20.31 ± 3.23, and 1.33 ± 0.15% ID/g at 0.5, 2, 4, and 24 h postinjection, respectively. The tumor uptake of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex was 1.6 and 3.4 times the tumor uptake of [99mTc]Tc(CO)3-NOTA-AocNle-CycMSHhex at 2 and 4 h postinjection, respectively. Meanwhile, the normal organ uptake of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex was lower than 1.8% ID/g at 2 h postinjection. The renal uptake of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex was only 1.73 ± 0.37, 0.73 ± 0.14, and 0.03 ± 0.01% ID/g at 2, 4, and 24 h postinjection, respectively. [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex showed high tumor to normal organ uptake ratios at 2 h postinjection. Single-photon emission computed tomography imaging revealed that the B16/F10 melanoma lesions could be clearly visualized by [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex at 2 h postinjection. Overall, the high tumor uptake and low kidney uptake of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex highlighted its potential for melanoma imaging and warranted the future evaluation of [188Re]Re(CO)3-NOTA-PEG2Nle-CycMSHhex for melanoma therapy.

Novel Al18F-NOTA-Conjugated Lactam-Cyclized α-Melanocyte-Stimulating Hormone Peptides with Enhanced Melanoma Uptake.

The purpose of this study was to evaluate the effect of linker on tumor targeting and biodistribution of Al18F-NOTA-PEG2Nle-CycMSHhex {Al18F-1,4,7-triazacyclononane-1,4,7-triyl-triacetic acid-poly(ethylene glycol)-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2} and Al18F-NOTA-AocNle-CycMSHhex {Al18F-NOTA-8-aminooctanoic acid-Nle-CycMSHhex} on melanoma-bearing mice. NOTA-PEG2Nle-CycMSHhex and NOTA-AocNle-CycMSHhex were synthesized using fluorenylmethoxycarbonyl (Fmoc) chemistry. The melanocortin-1 (MC1) receptor binding affinities of the peptides were determined on B16/F10 melanoma cells. The biodistribution of Al18F-NOTA-PEG2Nle-CycMSHhex and Al18F-NOTA-AocNle-CycMSHhex was determined on B16/F10 melanoma-bearing C57 mice. The melanoma imaging property of Al18F-NOTA-PEG2Nle-CycMSHhex was further examined on B16/F10 melanoma-bearing C57 mice because of its higher melanoma uptake and lower renal uptake than that of Al18F-NOTA-AocNle-CycMSHhex. The IC50 values of NOTA-PEG2/AocNle-CycMSHhex were 1.24 ± 0.07 and 2.75 ± 0.48 nM on B10/F10 cells. Al18F-NOTA-PEG2Nle-CycMSHhex and Al18F-NOTA-AocNle-CycMSHhex were readily prepared with more than 55% of radiolabeling yields and displayed melanocortin-1 receptor (MC1R)-specific binding on B16/F10 cells. Al18F-NOTA-PEG2Nle-CycMSHhex exhibited higher tumor uptake and lower kidney and liver uptake than Al18F-NOTA-AocNle-CycMSHhex at 1 and 2 h post injection. The tumor and renal uptakes of Al18F-NOTA-PEG2Nle-CycMSHhex were 17.44 ± 0.76 and 2.07 ± 0.43% ID/g at 1 h post injection, respectively. Al18F-NOTA-PEG2Nle-CycMSHhex showed the high tumor to normal organ uptake ratios after 1 h post injection. The B16/F10 melanoma lesions could be clearly visualized by positron emission tomography (PET) using Al18F-NOTA-PEG2Nle-CycMSHhex as an imaging probe at 1 and 2 h post injection. Overall, high tumor uptake, low kidney and liver uptake, and fast urinary clearance of Al18F-NOTA-PEG2Nle-CycMSHhex highlighted its potential as an MC1R-targeted imaging probe for melanoma detection.

Novel 64Cu-Labeled NOTA-Conjugated Lactam-Cyclized Alpha-Melanocyte-Stimulating Hormone Peptides with Enhanced Tumor to Kidney Uptake Ratios.

The aim of this study was to evaluate the effect of linker on tumor targeting and biodistribution of 64Cu-NOTA-PEG2Nle-CycMSHhex {64Cu-1,4,7-triazacyclononane-1,4,7-triyl-triacetic acid-polyethylene glycol-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2} and 64Cu-NOTA-AocNle-CycMSHhex {64Cu-NOTA-8-aminooctanoic acid-Nle-CycMSHhex} on melanoma-bearing mice. NOTA-PEG2Nle-CycMSHhex and NOTA-AocNle-CycMSHhex were synthesized and purified by HPLC. The melanocortin-1 (MC1) receptor binding affinities of the peptides were examined on B16/F10 melanoma cells. The biodistributions of 64Cu-NOTA-PEG2Nle-CycMSHhex and 64Cu-NOTA-AocNle-CycMSHhex were determined on B16/F10 melanoma-bearing C57 mice. The melanoma imaging property of 64Cu-NOTA-PEG2Nle-CycMSHhex was further examined on B16/F10 melanoma-bearing C57 mice because of its higher melanoma uptake than 64Cu-NOTA-AocNle-CycMSHhex. The IC50 values of NOTA-PEG2Nle-CycMSHhex and NOTA-AocNle-CycMSHhex were 1.24 ± 0.07 and 2.75 ± 0.48 nM on B10/F10 melanoma cells. 64Cu-NOTA-PEG2Nle-CycMSHhex and 64Cu-NOTA-AocNle-CycMSHhex were readily prepared with more than 90% radiolabeling yields and showed MC1R-specific binding on B16/F10 cells. 64Cu-NOTA-PEG2Nle-CycMSHhex exhibited higher tumor uptake than 64Cu-NOTA-AocNle-CycMSHhex at 0.5, 2, 4, and 24 h post-injection. The tumor uptake of 64Cu-NOTA-PEG2Nle-CycMSHhex was 16.23 ± 0.42, 19.59 ± 1.48, 12.83 ± 1.69, and 8.78 ± 2.29% ID/g at 0.5, 2, 4, and 24 h post-injection, respectively. Normal organ uptake of 64Cu-NOTA-PEG2Nle-CycMSHhex was lower than 2% ID/g at 2 h post-injection except for kidney uptake. The renal uptake of 64Cu-NOTA-PEG2Nle-CycMSHhex was 3.66 ± 0.52, 3.27 ± 0.52, and 1.47 ± 0.56 ID/g at 2, 4, and 24 h post-injection, respectively. 64Cu-NOTA-PEG2Nle-CycMSHhex showed high tumor to normal organ uptake ratios after 2 h post-injection. The B16/F10 melanoma lesions could be clearly visualized by positron emission tomography (PET) using 64Cu-NOTA-PEG2Nle-CycMSHhex as an imaging probe at 2 h post-injection. High tumor uptake and low kidney uptake of 64Cu-NOTA-PEG2Nle-CycMSHhex underscored its potential as an MC1R-targeted theranostic peptide for melanoma imaging and therapy.

A Two-Step Phenotypic Parameter Measurement Strategy for Overlapped Grapes under Different Light Conditions.

Phenotypic characteristics of fruit particles, such as projection area, can reflect the growth status and physiological changes of grapes. However, complex backgrounds and overlaps always constrain accurate grape border recognition and detection of fruit particles. Therefore, this paper proposes a two-step phenotypic parameter measurement to calculate areas of overlapped grape particles. These two steps contain particle edge detection and contour fitting. For particle edge detection, an improved HED network is introduced. It makes full use of outputs of each convolutional layer, introduces Dice coefficients to original weighted cross-entropy loss function, and applies image pyramids to achieve multi-scale image edge detection. For contour fitting, an iterative least squares ellipse fitting and region growth algorithm is proposed to calculate the area of grapes. Experiments showed that in the edge detection step, compared with current prevalent methods including Canny, HED, and DeepEdge, the improved HED was able to extract the edges of detected fruit particles more clearly, accurately, and efficiently. It could also detect overlapping grape contours more completely. In the shape-fitting step, our method achieved an average error of 1.5% in grape area estimation. Therefore, this study provides convenient means and measures for extraction of grape phenotype characteristics and the grape growth law.

Novel [99mTc]-Tricarbonyl-NOTA-Conjugated Lactam-Cyclized Alpha-MSH Peptide with Enhanced Melanoma Uptake and Reduced Renal Uptake.

The purpose of this study was to examine the melanoma targeting and imaging properties of 99mTc(CO)3-NOTA-GGNle-CycMSHhex {1,4,7-triazacyclononane-1,4,7-triyl-triacetic acid-GlyGlyNle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2} and 99mTc(CO)3-NODAGA-GGNle-CycMSHhex {1,4,7-triazacyclononane,1-gluteric acid-4,7-acetic acid-GlyGlyNle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2} on B16/F10 melanoma-bearing C57 mice to demonstrate the feasibility of NOTA/NODAGA as metal chelators for 99mTc(CO)3+ radiolabeling. NOTA/NODAGA-GGNle-CycMSHhex were synthesized using fluorenylmethoxycarbonyl (Fmoc) chemistry. The melanocortin-1 (MC1) receptor binding affinities of the peptides were determined on B16/F10 melanoma cells. The biodistribution of 99mTc(CO)3-NOTA-GGNle-CycMSHhex and 99mTc(CO)3-NODAGA-GGNle-CycMSHhex were determined on B16/F10 melanoma-bearing C57 mice at 2 h postinjection to select a lead peptide for further evaluation. The melanoma targeting and imaging properties of 99mTc(CO)3-NOTA-GGNle-CycMSHhex and 99mTc(CO)3-NODAGA-GGNle-CycMSHhex were determined on B16/F10 melanoma-bearing C57 mice. The IC50 values of NOTA/NODAGA-GGNle-CycMSHhex were 0.8 ± 0.1 and 0.9 ± 0.1 nM on B16/F10 cells. 99mTc(CO)3-NOTA-GGNle-CycMSHhex and 99mTc(CO)3-NODAGA-GGNle-CycMSHhex were readily prepared via the [99mTc(CO)3(OH2)3]+ intermediate and displayed MC1R-specific binding on B16/F10 cells. 99mTc(CO)3-NOTA-GGNle-CycMSHhex was further evaluated as a lead peptide because of its higher tumor uptake (19.76 ± 3.62% ID/g) and lower kidney uptake (1.59 ± 0.52% ID/g) at 2 h postinjection than 99mTc(CO)3-NODAGA-GGNle-CycMSHhex. The B16/F10 melanoma uptake of 99mTc(CO)3-NOTA-GGNle-CycMSHhex was 16.07 ± 4.47, 19.76 ± 3.62, 11.30 ± 2.81, and 3.16 ± 2.28% ID/g at 0.5, 2, 4, and 24 h postinjection, respectively. 99mTc(CO)3-NOTA-GGNle-CycMSHhex showed high tumor to normal organ uptake ratios after 2 h postinjection. The B16/F10 melanoma lesions were clearly visualized by SPECT/CT using 99mTc(CO)3-NOTA-GGNle-CycMSHhex as an imaging probe at 2 h postinjection. High tumor uptake, low kidney uptake, and fast urinary clearance of 99mTc(CO)3-NOTA-GGNle-CycMSHhex highlighted its potential for melanoma imaging and facilitated the evaluation of 188Re(CO)3-NOTA-GGNle-CycMSHhex for melanoma therapy.

Facile preparation of a novel Ga-67-labeled NODAGA-conjugated lactam-cyclized alpha-MSH peptide at room temperature for melanoma targeting.

In this study, the melanoma targeting property of 67Ga-NODAGA-GGNle-CycMSHhex {1,4,7-triazacyclononane,1-gluteric acid-4,7-acetic acid-GlyGlyNle-c[Asp-His-D-Phe-Arg-Trp-Lys]-CONH2} was determined on B16/F10 melanoma-bearing C57 mice to demonstrate the feasibility of NODAGA as a radiometal chelator for facile room temperature radiolabeling of NODAGA-GGNle-CycMSHhex. The IC50 value of NODAGA-GGNle-CycMSHhex was 0.87 ± 0.12 nM on B16/F10 melanoma cells. 67Ga-NODAGA-GGNle-CycMSHhex was readily prepared at room temperature with greater than 98% radiolabeling yield and displayed MC1R-specific binding on B16/F10 melanoma cells. The B16/F10 melanoma uptake of 67Ga-NODAGA-GGNle-CycMSHhex was 10.31 ± 0.78, 14.96 ± 1.34, 13.7 ± 3.33 and 10.4 ± 2.2% ID/g at 0.5, 2, 4 and 24 h post-injection, respectively. Approximately 85% of the injected dose was cleared out the body via urinary system at 2 h post-injection. 67Ga-NODAGA-GGNle-CycMSHhex showed high tumor/blood, tumor/muscle and tumor/skin uptake ratios after 2 h post-injection. Overall, 67Ga-NODAGA-GGNle-CycMSHhex could be easily prepared at room temperature and exhibited favorable melanoma targeting property, suggesting the potential use of NODAGA as a radiometal chelator for facile room temperature radiolabeling of α-MSH peptides.

Evaluation of a Novel Pb-203-Labeled Lactam-Cyclized Alpha-Melanocyte-Stimulating Hormone Peptide for Melanoma Targeting.

The purpose of this study is to examine the melanocortin-1 receptor (MC1R) targeting and specificity of 203Pb-DOTA-GGNle-CycMSHhex in melanoma cells and tumors to facilitate its potential therapeutic application when labeled with 212Pb. The MC1R-specific targeting and imaging properties of 203Pb-DOTA-GGNle-CycMSHhex were determined on B16/F1 and B16/F10 murine melanoma cells and in B16/F1 flank melanoma-, B16/F10 flank melanoma-, and B16/F10 pulmonary metastatic melanoma-bearing C57 mice. 203Pb-DOTA-GGNle-CycMSHhex displayed MC1R-specific binding on B16/F1 and B16/F10 melanoma cells and tumors. B16/F1 flank melanoma, B16/F10 flank melanoma, and B16/F10 pulmonary metastatic melanoma lesions could be clearly imaged by single photon emission computed tomography (SPECT) using 203Pb-DOTA-GGNle-CycMSHhex as an imaging probe. The favorable melanoma targeting and imaging properties highlighted the potential of 203Pb-DOTA-GGNle-CycMSHhex as a MC1R-targeting melanoma imaging probe and warranted the evaluation of 212Pb-DOTA-GGNle-CycMSHhex for melanoma therapy in future studies.

Evaluation of novel 111In-labeled gonadotropin-releasing hormone peptides for human prostate cancer imaging.

The purpose of this study was to evaluate the tumor targeting and imaging properties of novel 111In-labeled gonadotropin-releasing hormone (GnRH) peptides for human prostate cancer. Three new 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-linker-d-Phe-(d-Lys6-GnRH) peptides with different hydrocarbon linkers were designed to evaluate their effects on GnRH receptor binding affinities. The Aoc (aminooctanoic acid) linker was better than ßAla (3-aminopropanoic acid) and Aun (aminoundecanoic acid) linkers in retaining strong receptor binding affinity. DOTA-Aoc-d-Phe-(d-Lys6-GnRH) exhibited 6.6±0.1nM GnRH receptor binding affinity. 111In-DOTA-Aoc-d-Phe-(d-Lys6-GnRH) exhibited fast tumor uptake and urinary clearance in DU145 human prostate cancer-xenografted nude mice. The DU145 tumor lesions could be clearly visualized by single photon emission computed tomography (SPECT)/CT using 111In-DOTA-Aoc-d-Phe-(d-Lys6-GnRH) as an imaging probe, providing an insight into the design of new GnRH peptides for prostate cancer in the future.

Metastatic melanoma imaging using a novel Tc-99m-labeled lactam-cyclized alpha-MSH peptide.

The purpose of this study was to determine the metastatic melanoma imaging property of 99mTc(EDDA)-HYNIC-Aoc-Nle-CycMSHhex {hydrazinonicotinamide-8-aminooctanoic acid-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2}. HYNIC-Aoc-Nle-CycMSHhex was synthesized using fluorenylmethyloxy carbonyl (Fmoc) chemistry. The IC50 value of HYNIC-Aoc-Nle-CycMSHhex was 0.78 ±â€¯0.13 nM for B16/F10 melanoma cells. 99mTc(EDDA)-HYNIC-Aoc-Nle-CycMSHhex displayed significantly higher uptake (14.26 ±â€¯2.74 and 10.45 ±â€¯2.31% ID/g) in B16/F10 metastatic melanoma-bearing lung than that in normal lung (0.90 ±â€¯0.15 and 0.53 ±â€¯0.14% ID/g) at 2 and 4 h post-injection, respectively. B16/F10 pulmonary metastatic melanoma lesions were clearly visualized by SPECT/CT using 99mTc(EDDA)-HYNIC-Aoc-Nle-CycMSHhex as an imaging probe at 2 h post-injection, underscoring its potential as an imaging probe for metastatic melanoma detection.

Imaging human melanoma using a novel Tc-99m-labeled lactam bridge-cyclized alpha-MSH peptide.

In this study, the human melanoma targeting property of (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex {hydrazinonicotinamide-8-aminooctanoic acid-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2} was determined in M21 human melanoma-xenografts to demonstrate its potential for human melanoma imaging. The IC50 value of HYNIC-AocNle-CycMSHhex was 0.48±0.01nM in M21 human melanoma cells (1281receptors/cell). The M21 human melanoma uptake of (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex was 4.03±1.25, 3.26±1.23 and 3.36±1.48%ID/g at 0.5, 2 and 4h post-injection, respectively. Approximately 92% of injected dose cleared out the body via urinary system at 2h post-injection. (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex showed high tumor/blood, tumor/muscle and tumor/skin uptake ratios after 2h post-injection. The M21 human melanoma-xenografted tumor lesions were clearly visualized by SPECT/CT using (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex as an imaging probe at 2h post-injection. Overall, (99m)Tc(EDDA)-HYNIC-AocNle-CycMSHhex exhibited favorable human melanoma imaging property, highlighting its potential as an imaging probe for human metastatic melanoma detection.

Role of a Conserved Tyrosine Residue in the FMN-Heme Interdomain Electron Transfer in Inducible Nitric Oxide Synthase.

The interdomain electron transfer (IET) between the flavin mononucleotide (FMN) and heme domains is essential in the biosynthesis of nitric oxide (NO) by the NO synthase (NOS) enzymes. A conserved tyrosine residue in the FMN domain (Y631 in human inducible NOS) was proposed to be a key part of the electron transfer pathway in the FMN/heme docked complex model. In the present study, the FMN-heme IET kinetics in the Y631F mutant and wild type of a bidomain oxygenase/FMN construct of human inducible NOS were determined by laser flash photolysis. The rate constant of the Y631F mutant is significantly decreased by ∼75% (compared to the wild type), showing that the tyrosine residue indeed facilitates the FMN-heme IET through the protein medium. The IET rate constant of the wild type protein decreases from 345 to 242 s-1 on going from H2O to 95% D2O, giving a solvent kinetic isotope effect of 1.4. In contrast, no deuterium isotope effect was observed for the Tyr-to-Phe mutant. Moreover, an appreciable change in the wild type iNOS IET rate constant value was observed upon changing pH. These results indicate that the FMN-heme IET is proton coupled, in which the conserved tyrosine residue may play an important role.

Tc-99m-labeled RGD-conjugated alpha-melanocyte stimulating hormone hybrid peptides with reduced renal uptake.

The purpose of this study was to examine whether the replacement of the positively-charged Lys or Arg linker with a neutral linker could reduce the renal uptake of Arg-Gly-Asp (RGD)-conjugated alpha-melanocyte stimulating hormone (α-MSH) hybrid peptide. The RGD motif {cyclic(Arg-Gly-Asp-DTyr-Asp)} was coupled to [Cys(3,4,10), D-Phe(7), Arg(11)]α-MSH3-13 {(Arg(11))CCMSH} through the neutral ßAla or Ahx {aminohexanoic acid} linker (replacing the Lys or Arg linker) to generate novel RGD-ßAla-(Arg(11))CCMSH and RGD-Ahx-(Arg(11))CCMSH hybrid peptides. The receptor-binding affinity and cytotoxicity of RGD-ßAla-(Arg(11))CCMSH and RGD-Ahx-(Arg(11))CCMSH were determined in B16/F1 melanoma cells. The melanoma targeting and imaging properties of (99m)Tc-RGD-ßAla-(Arg(11))CCMSH and (99m)Tc-RGD-Ahx-(Arg(11))CCMSH were determined in B16/F1 melanoma-bearing C57 mice. The replacement of the Lys or Arg linker with the ßAla or Ahx linker retained nanomolar receptor-binding affinities and remarkable cytotoxicity of RGD-ßAla-(Arg(11))CCMSH and RGD-Ahx-(Arg(11))CCMSH. The receptor-binding affinities of RGD-ßAla-(Arg(11))CCMSH and RGD-Ahx-(Arg(11))CCMSH were 0.8 ± 0.05 and 1.3 ± 0.1 nM. Three-hour incubation with 0.1 µM of RGD-ßAla-(Arg(11))CCMSH and RGD-Ahx-(Arg(11))CCMSH decreased the survival percentages of B16/F1 cells by 71 and 67 % as compared to the untreated control cells 5 days post the treatment. The replacement of the Arg linker with the ßAla or Ahx linker reduced the non-specific renal uptake of (99m)Tc-RGD-ßAla-(Arg(11))CCMSH and (99m)Tc-RGD-Ahx-(Arg(11))CCMSH by 62 and 61 % at 2 h post-injection. (99m)Tc-RGD-ßAla-(Arg(11))CCMSH displayed higher melanoma uptake than (99m)Tc-RGD-Ahx-(Arg(11))CCMSH at 0.5, 2, 4, and 24 h post-injection. Enhanced tumor to kidney uptake ratio of (99m)Tc-RGD-ßAla-(Arg(11))CCMSH warranted the further evaluation of (188)Re-labeled RGD-ßAla-(Arg(11))CCMSH as a novel MC1 receptor-targeting therapeutic peptide for melanoma treatment in the future.

Intimacy and a deadly feud: the interplay of autophagy and apoptosis mediated by amino acids.

Autophagy (i.e., "self-eating") and apoptosis (i.e., type I programmed cell death) are essential and intimately involved in molecular, cellular, and whole-body homeostasis in humans and animals. Autophagy has been categorized as a mechanism of intracellular degradation, recycling, defense, and survival. To date, three types of autophagy have been identified: macroautophagy, microautophagy, and chaperone-mediated autophagy. Recent discoveries strongly suggest that macroautophagy also modulates type II programmed cell death under specific circumstances. Autophagy and apoptosis are fundamentally distinct processes, but are interconnected by common stress initiators and intermediate regulators. During the past two decades, the role of amino acid metabolism and signaling in the regulation of apoptosis and autophagy has been intensively studied. In this review, we summarize recent advances in our understanding of the molecular mechanisms that regulate both autophagy and apoptosis in the context of amino acid signaling.

Probing the Hydrogen Bonding of the Ferrous-NO Heme Center of nNOS by Pulsed Electron Paramagnetic Resonance.

Oxidation of L-arginine (L-Arg) to nitric oxide (NO) by NO synthase (NOS) takes place at the heme active site. It is of current interest to study structures of the heme species that activates O2 and transforms the substrate. The NOS ferrous-NO complex is a close mimic of the obligatory ferric (hydro)peroxo intermediate in NOS catalysis. In this work, pulsed electron-nuclear double resonance (ENDOR) spectroscopy was used to probe the hydrogen bonding of the NO ligand in the ferrous-NO heme center of neuronal NOS (nNOS) without a substrate and with L-Arg or N-hydroxy-L-arginine (NOHA) substrates. Unexpectedly, no H-bonding interaction connecting the NO ligand to the active site water molecule or the Arg substrate was detected, in contrast to the results obtained by X-ray crystallography for the Arg-bound nNOS heme domain [Li et al. J. Biol. Inorg. Chem. 2006, 11, 753-768]. The nearby exchangeable proton in both the no-substrate and Arg-containing nNOS samples is located outside the H-bonding range and, on the basis of the obtained structural constraints, can belong to the active site water (or OH). On the contrary, in the NOHA-bound sample, the nearby exchangeable hydrogen forms an H-bond with the NO ligand (on the basis of its distance from the NO ligand and a nonzero isotropic hfi constant), but it does not belong to the active site water molecule because the water oxygen atom (detected by (17)O ENDOR) is too far. This hydrogen should therefore come from the NOHA substrate, which is in agreement with the X-ray crystallography work [Li et al. Biochemistry 2009, 48, 10246-10254]. The nearby nonexchangeable hydrogen atom assigned as H(ε) of Phe584 was detected in all three samples. This hydrogen atom may have a stabilizing effect on the NO ligand and probably determines its position.

Linker modification reduced the renal uptake of technetium-99m-labeled Arg-Ala-Asp-conjugated alpha-melanocyte stimulating hormone peptide.

The purpose of this study was to examine the biodistribution of (99m)Tc-RAD-Arg-(Arg(11))CCMSH in B16/F1 melanoma-bearing C57 mice to determine whether the replacement of the Lys linker with an Arg linker could decrease the renal uptake of (99m)Tc-RAD-Arg-(Arg(11))CCMSH. (99m)Tc-RAD-Arg-(Arg(11))CCMSH exhibited rapid and high tumor uptake (17.98±4.96% ID/g at 2h post-injection) in B16/F1 melanoma-bearing C57 mice. As compared to (99m)Tc-RAD-Lys-(Arg(11))CCMSH, the replacement of the Lys linker with an Arg linker dramatically decreased the renal uptake of (99m)Tc-RAD-Arg-(Arg(11))CCMSH by 68%, 62%, 73% and 64% at 0.5, 2, 4 and 24h post-injection, respectively. Flank B16/F1 melanoma lesions were clearly imaged at 2h post-injection using (99m)Tc-RAD-Arg-(Arg(11))CCMSH as an imaging probe.

Introduction of D-phenylalanine enhanced the receptor binding affinities of gonadotropin-releasing hormone peptides.

The purpose of this study was to examine whether the introduction of D-Phe could improve the GnRH receptor binding affinities of DOTA-conjugated D-Lys(6)-GnRH peptides. Building upon the construct of DOTA-Ahx-(D-Lys(6)-GnRH1) we previously reported, an aromatic amino acid of D-Phe was inserted either between the DOTA and Ahx or between the Ahx and D-Lys(6) to generate new DOTA-D-Phe-Ahx-(D-Lys(6)-GnRH) or DOTA-Ahx-D-Phe-(D-Lys(6)-GnRH) peptides. Compared to DOTA-Ahx-(D-Lys(6)-GnRH1) (36.1 nM), the introduction of D-Phe improved the GnRH receptor binding affinities of DOTA-D-Phe-Ahx-(D-Lys(6)-GnRH) (16.3 nM) and DOTA-Ahx-D-Phe-(D-Lys(6)-GnRH) (7.6 nM). The tumor targeting and pharmacokinetic properties of (111)In-DOTA-Ahx-D-Phe-(D-Lys(6)-GnRH) was determined in MDA-MB-231 human breast cancer-xenografted nude mice. Compared to (111)In-DOTA-Ahx-(D-Lys(6)-GnRH1), (111)In-DOTA-Ahx-D-Phe-(D-Lys(6)-GnRH) exhibited comparable tumor uptake with faster renal and liver clearance. The MDA-MB-231 human breast cancer-xenografted tumors were clearly visualized by single photon emission computed tomography (SPECT) using (111)In-DOTA-Ahx-D-Phe-(D-Lys(6)-GnRH) as an imaging probe, providing a new insight into the design of new GnRH peptides in the future.

Elevating theranostics: The emergence and promise of radiopharmaceutical cell-targeting heterodimers in human cancers.

Optimal therapeutic and diagnostic efficacy is essential for healthcare's global mission of advancing oncologic drug development. Accurate diagnosis and detection are crucial prerequisites for effective risk stratification and personalized patient care in clinical oncology. A paradigm shift is emerging with the promise of multi-receptor-targeting compounds. While existing detection and staging methods have demonstrated some success, the traditional approach of monotherapy is being reevaluated to enhance therapeutic effectiveness. Heterodimeric site-specific agents are a versatile solution by targeting two distinct biomarkers with a single theranostic agent. This review describes the innovation of dual-targeting compounds, examining their design strategies, therapeutic implications, and the promising path they present for addressing complex diseases.

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.