99mTc-labeled bombesin analog for breast cancer identification

Bombesin is a tetradecapeptide that binds specifically to gastrin releasing peptide receptors in humans. Several forms of cancer, including lung, prostate, breast, and colon express receptors for bombesin-like peptides. Radiolabeled bombesin analogs with a high affinity for these receptors might therefore be used for scintigraphic imaging of these tumor types. A truncated bombesin derivative (HYNIC-βAla-Bombesin_(7–14)) was radiolabeled with technetium-99m using EDDA and tricine as coligands. In vitro stability was evaluated in presence of plasma and excess of cysteine. The receptor-binding affinity assays was evaluated in MDA-MB-231 cancer cell line. In addition, in vivo biodistribution was performed in nude mice bearing breast tumor. In vitro assay showed a good affinity for the MDA-MB-231 cell line, showing 20.0 % of internalization at 4 h post-administration. ^99mTc-HYNIC-βAla-Bombesin_(7–14) biodistribution revealed a rapid clearance and a significant renal excretion. In addition, tumor uptake was higher than non-excretory organs, such as the spleen, the liver, and muscles. Tumor-to-muscle and tumor-to-blood ratios for ^99mTc-HYNIC-βAla-Bombesin_(7–14) showed high values at 4 h post-injection (5.34 and 4.55, respectively). Furthermore, blocked studies using cold bombesin peptide were performed, which demonstrated an important decrease in tumor uptake, indicating a tumor specificity for ^99mTc-HYNIC-βAla-Bombesin_(7–14). The ^99mTc-HYNIC-βAla-Bombesin_(7–14) displayed suitable radiochemical characteristics, and adequate affinity to breast tumor cells (MDA-MB-231). Therefore, this analog can be considered as a candidate for the identification of bombesin-positive tumors.     

18FDG conjugated magnetic nanoparticle probes: synthesis and in vitro investigations on MCF-7 breast cancer cells

¹⁸FDG conjugated magnetic iron oxide nanoparticles (MNPs) were synthesized as PET-MR hybrid imaging agent. Synthesized and characterized NPs were then applied to MCF-7 human breast cancer cells. ¹⁸FDG conjugated MNPs exhibited the cell incorporation ratio up to 30 %. As well as the characterization studies, apoptotic effects were observed depending on the cellular incorporations by the time. In conclusion, synthesized structures could have a potential as hybrid imaging agent in PET-MR imaging systems besides apoptotic effect on cancer cells.     

Synthesis and biological evaluation of fatty acid derivatives for myocardial imaging containing [<Superscript>99m</Superscript>Tc(CO)<Subscript>3</Subscript>]<Superscript>+</Superscript>

Radiolabeled fatty acids as myocardial metabolic agent are used for detecting ischemic heart disease, however, no ^99mTc-labeled fatty acids have potential use in clinical diagnosis. In this work, five fatty acid analogues labeled with ^99mTc were firstly synthesized and characterized, their biological behaviors were investigated. All Radiotracers had good stability when incubated in rat serum for 3 h at 37 °C. ^99mTc -CpT-12-ODPPA (8b) showed higher initial myocardial uptake (8.17% ID/g at 1 min postinjection) and good heart/blood ratio (2.58 at 30 min postinjection). ^99mTc-11-dpa-OUFA (2b) as positively charged lipophilic compounds had reasonable heart uptake (5.59% ID/g at 1 min postinjection) and good retention (1.89% ID/g at 60 min postinjection). Unfortunately, no great improvement was obtained by the five ^99mTc-labeled fatty acid analogues for the short myocardial retention and poor heart/liver ratios.     

In vivo characterization of 99mTc-spermine in mice bearing human breast cancer xenografts

The usability of ^99mTc-spermine for human breast tumor imaging was evaluated. Mice bearing MDA-MB-231 breast tumor were used for SPECT imaging and biodistribution study. Tumor was imaged clearly after injection with ^99mTc-spermine. The accumulation of ^99mTc-spermine was much lower in chest region than that of general breast tumor imaging agent ^99mTc-MIBI. It suggests that ^99mTc-spermine is promising for breast cancer imaging.     

Synthesis,characterization and biodistribution of 99mTc-Bioquin-HMPAO (99mTc-BH) as a novel brain imaging agent

Recently, the development of novel brain imaging agents has aroused much interest thanks to limited number of brain cancer or diseases diagnosis agents. It is aimed to synthesize a novel brain imaging agent including a promise for further studies on AD diagnosis potential and investigate its bioaffinity with biodistribution studies on healthy Balb/c mice. A novel radiolabeled agent was synthesized and characterized. Quality control of ^99mTc-BH was performed utilizing solvent extraction and chromatographic (Radio TLC and Radio HPLC) methods. Bioaffinity of the ^99mTc-BH was investigated on male Balb/c mice at various time points (5, 30, 60, 120 min post-injection). Paper electrophoresis showed that ^99mTc-BH has a neutral structure. Radiochemical purity of ^99mTc-BH was over 95 % with appropriate stability for imaging period. Selected brain regions have uptakes over 4 % ID/g following intravenous injection. Hippocampus has uptake approximately 10 % ID/g. ^99mTc-BH has shown brain uptake, so it may prove to be valuable for brain imaging as a novel technetium-labeled agent. Further investigations with AD animal model are our on going effort to show that this agent has AD diagnosis potential.     

Synthesis and evaluation of a series of 99mTc-labelled zoledronic acid derivatives as potential bone seeking agents

Developing novel superior bone-seeking radiopharmaceuticals for the detection of malignant bone lesions could further improve the diagnostic value of routine bone scanning. A series of radiolabeled diphosphonates (^99mTc-EIPrDP, ^99mTc-EIBDP and ^99mTc-EIPeDP) have been designed and synthesized successfully in high chemical yields and radiochemical purity. The in vitro and in vivo biological properties were systematically investigated and compared. The biodistribution in mice shows that ^99mTc-EIPrDP has higher bone uptake (13.3 ± 1.23) than those of ^99mTc-EIBDP and ^99mTc-EIPeDP (11.7 ± 0.28 and 8.69 ± 0.04 %ID/g) at 1–2 h post injection. It also has the highest uptake ratio of bone to muscle, spleen and heart, respectively, and faster blood clearance in early times. The present study indicates that ^99mTc-EIPrDP holds great promise as a bone imaging agent.     

Synthesis and preliminary evaluation of 99mTc-spermine as a tumor imaging agent

Polyamines are essential for the growth and survival of all cells with biosynthesis and transportation of polyamines being very active in tumors. With the aim of developing a new tumor imaging agent, the endogenous polyamine, spermine was labeled with ^99mTc, and its characters were also evaluated via in vitro and in vivo studies. ^99mTc-labeled spermine probe (^99mTc-spermine) was synthesized by the direct pretinning procedure and the labeling procedure was optimized with regard to the pH, reaction time, amounts of spermine and SnCl₂. The stability of the ^99mTc-spermine and its capacity to accumulate into 4T1 tumor cells were also evaluated. Biodistribution of ^99mTc-spermine was studied in 4T1 tumor-bearing mice. In the optimal conditions, the whole radiosynthesis was accomplished within 10 min with a decay-corrected yield of 96.5 ± 1.3 % and radiochemical purity of >95 %.^99mTc-spermine was stable at both 37 and 4 °C for at least 6 h. In vitro tests revealed that the ability of ^99mTc-spermine to penetrate in 4T1 tumour cells and an excess of spermine blocked the accumulation of the compound in the models. Biodistribution studies showed a high tumor uptake peaked at 30 min post-injection with 1.82 ± 0.19 % ID%/g. The tumor to muscle uptake ratios of the probe were 3.60 ± 0.51, 4.48 ± 0.29, 4.82 ± 0.18, 5.64 ± 0.10, respectively at 30 min, 1, 2 and 4 h postinjection. Block studies indicated that ^99mTc-spermine had specific binding of tumor via polyamine transport systems. ^99mTc-spermine is a promising radiopharmaceutical in tumor imaging. Further studies are required to determine the usability of ^99mTc–spermine for diagnosis purposes.     

A perspective on <Superscript>99m</Superscript>Tc and <Superscript>125/131</Superscript>I labeled receptor targeted compounds and their in vitro/in vivo affinities

A novel quinoline derivative, 2,2′-[(5-chloro-8-hydroxyquinoline-7-yl) methylazanediyl] diacetic acid (CHQMADA) was labeled with ^99mTc using SnCl₂·2H₂O as a reducing agent to give a complex with a labeling yield 94 %. Also [^99mTc(H₂O)₃(CO)₃]⁺ was prepared by heating at 100 °C for 30 min using 2 mg CHQMADA at pH 8 to give a labeling yield >99 %. ^99mTc-(CO)₃ CHQMADA and ^99mTc-Sn(II)-CHQMADA showed tissue uptake (target to non target T/NT = 6.80 ± 0.22) and (T/NT = 5.65 ± 0.34) respectively in Escherichia coli induced infection, which is higher than the commercially available ^99mTc-ciprofloxacin (T/NT = 3.80 ± 0.80). In conclusion, both complexes were able to differentiate between septic and aseptic inflammation with superiority of [^99mTc-(CO)₃ CHQMADA].     

Synthesis of 99mTc-oxybutynin for M3-receptor-mediated imaging of urinary bladder

Radiolabeling of oxybutynin, a muscarinic acetylcholine (mACh) receptor antagonist agent with ^99mTc is of considerable interest for imaging of urinary bladder. This study is aimed to optimize radiolabeling yield of oxybutynin with ^99mTc using SnCl₂·2H₂O as a reducing agent with respect to factors that affect the reaction conditions such as oxybutynin amount, stannous chloride amount, reaction time and pH of the reaction mixture. In vitro stability of the radiolabeled complex was checked and it was found to be stable for up to 8 h. ^99mTc-oxybutynin was injected via subcutaneous and intravenous administration routes into normal Sprague?CDawley rats. Biodistribution studies have revealed that ^99mTc-oxybutynin exhibits high affinity and specificity for the muscarinic M₃ subtype located on the smooth muscle of urinary bladder relative to the M₁ and M₂ subtypes of the G protein coupled receptor (GPCR) superfamily. In vivo uptake of subcutaneous ^99mTc-oxybutynin in urinary bladder was 19.6 ± 0.42% ID at 0.5 h, whereas in intravenous administration route the accumulation in the urinary bladder was found to be 9.4 ± 0.31% ID at 0.5 h post injection. Administration of cold oxybutynin effectively blocked urinary bladder uptake and further confirms the high specificity of this complex for the M₃ receptor.     

Evaluation of labelling conditions,quality control and biodistribution study of 99mTc-5-aminolevulinic acid (5-ALA): a potential liver imaging agent

Labelling of 5-aminolevulinic acid (5-ALA) with ^99mTc was achieved by using SnCl₂·2H₂O as reducing agent. Radiochemical purity and labelling efficiency was determined by instant thin layer chromatography/paper chromatography. Efficiency of labelling was dependent on many parameters such as amount of ligand, reducing agent, pH, and time of incubation. ^99mTc labelled 5-ALA remained stable for 24 h in human serum. Tissue biodistribution of ^99mTc-5-ALA was evaluated in Sprague–Dawley rats. Biodistribution study (% ID/g) in rats revealed that ^99mTc-5-ALA was accumulated significantly in liver, spleen, stomach and intestine after half hour, 4 and 24 h. Significant activity was noted in bladder and urine at 4 h. High liver uptake of ^99mTc-5-ALA makes it a promising liver imaging agent.     

Synthesis and biological evaluation of novel 99mTc-oxo and 99mTc-nitrido complexes with phenylalanine dithiocarbamate for tumor imaging

In this study, phenylalanine dithiocarbamate (PHEDTC) ligand was successfully synthesized and then radiolabeled with [^99mTcO]³⁺ core and [^99mTc≡N]²⁺ core to produce ^99mTcO–PHEDTC and ^99mTcN–PHEDTC, respectively. Both complexes were prepared with high radiochemical purity and had good stability. The partition coefficient results showed they were hydrophilic, while ^99mTcN–PHEDTC was more hydrophilic than ^99mTcO–PHEDTC. The biodistribution study in mice bearing S 180 tumor showed that ^99mTcO–PHEDTC and ^99mTcN–PHEDTC had high tumor uptake at 2 h post-injection, 1.91 and 1.21, respectively. The good uptake and retention in tumor together with favorable tumor-to-muscle ratios make them promising candidates for further evaluation as potential tumor imaging agents.     

New salen-type manganese(III) Schiff base complexes derived from meso-1,2-diphenyl-1,2-ethylenediamine: In vitro anticancer activity,mechanism of action,and molecular docking studies

Four new manganese(III) Schiff base complexes (1–4) were synthesized and characterized. The complexes have general formula [MnClL^x] in which L represents a Schiff base ligand derived from condensation of meso-1,2-diphenyl-1,2-ethylenediamine with salicylaldehyde or its 3-OMe-, 5-Br-, or 5-OMe-derivatives (x = 1–4, respectively). The crystal structure of [MnClL¹] (1) was characterized by X-ray crystallography. The in vitro anticancer activity of these complexes was evaluated by MTT and apoptosis assays against human breast (MCF-7) and liver (Hep G2) cancer cells. The complexes exhibited considerable antiproliferative activity against both cell lines (IC₅₀ = 10.8–21.02 μM) comparable to cis-platin, except 4 (MCF-7). The highest activity was found for 1 with IC₅₀ values of 13.62 μM (MCF-7) and 10.8 μM (Hep G2). Flow cytometry experiments showed that 1 induced apoptosis on MCF-7 tumor cell line. Docking simulations using AUTODOCK were also carried out. The results showed that all complexes fitted into the minor groove region of DNA.     

Growth Inhibition and Apoptotic Effect of Pine Extract and Abietic Acid on MCF-7 Breast Cancer Cells via Alteration of Multiple Gene Expressions Using In Vitro Approach

In vitro anti-proliferative activity of Pinus palustris extract and its purified abietic acid was assessed against different human cancer cell lines (HepG-2, MCF-7 and HCT-116) compared to normal WI-38 cell line. Abietic acid showed more promising IC₅₀ values against MCF-7 cells than pine extract (0.06 µg/mL and 0.11 µM, respectively), with insignificant cytotoxicity toward normal fibroblast WI-38 cells. Abietic acid triggered both G₂/M cell arrest and subG₀-G₁ subpopulation in MCF-7, compared to SubG₀-G₁ subpopulation arrest only for the extract. It also induced overexpression of key apoptotic genes (Fas, FasL, Casp3, Casp8, Cyt-C and Bax) and downregulation of both proliferation (VEGF, IGFR1, TGF-β) and oncogenic (C-myc and NF-κB) genes. Additionally, abietic acid induced overexpression of cytochrome-C protein. Furthermore, it increased levels of total antioxidants to diminish carcinogenesis and chemotherapy resistance. P. palustris is a valuable source of active abietic acid, an antiproliferative agent to MCF-7 cells through induction of apoptosis with promising future anticancer agency in breast cancer therapy.     

Biodistribution and imaging of <Superscript>99m</Superscript>Tc-MAVGG-adenine in tumor bearing mice

To increase the tumor uptake of Val-Gly-Gly (VGG), adenine was introduced into the peptide. N-mercaptoacetyl-VGG-adenine (MAVGG-adenine) and MAVGG were labeled with ^99mTc using a solution of SnCl₂ and tartaric acid as reducing agent. Biodistribution in mice bearing the S180 tumor was measured and γ imaging was performed. Compared with MAVGG, adenine conjugated MAVGG had higher tumor uptake and tumor to normal tissue ratios, which suggested that the tumor uptake property of a peptide may be improved by introducing a nucleotide base. The high contrasted tumor images of ^99mTc-MAVGG-adenine also suggested its potential utility as tumor imaging agent.     

Arene Ru(II) Complexes Acted as Potential KRAS G-Quadruplex DNA Stabilizer Induced DNA Damage Mediated Apoptosis to Inhibit Breast Cancer Progress

A series of arene Ru(II) complexes, [(η⁶-MeC₆H₅)Ru(L)Cl]Cl, (L=o-ClPIP, 1; m-ClPIP, 2 and p-ClPIP, 3) (o-ClPIP=2-(2-chlorophenyl)imidazo[4,5-f][1,10]phenanthroline; m-ClPIP=2-(3-chlorophenyl)imidazo[4,5-f][1,10]phenanthroline; p-ClPIP=2-(4-chlorophenyl)imidazo[4,5-f][1,10]phenanthroline) was synthesized and investigated as a potential apoptosis inducer in chemotherapy. Spectroscopy and molecular docking simulations show that 1 exhibits moderated binding affinity to KRAS G-quadruplex DNA by groove mode. Further, in vitro studies reveal that 1 displays inhibitory activity against MCF-7 growth with IC₅₀ = 3.7 ± 0.2 μM. Flow cytometric analysis, comet assay, and immunofluorescence confirm that 1 can induce the apoptosis of MCF-7 cells and G0/G1 phase arrest through DNA damage. In summary, the prepared arene Ru(II) complexes can be developed as a promising candidate for targeting G-quadruplex structure to induce the apoptosis of breast cancer cells via binding and stabilizing KRAS G-quadruplex conformation on oncogene promoter.     

Synthesis,labeling and biodistribution of <Superscript>99m</Superscript>Tc-3-amino-2-quinoxalin-carbonitrile 1,4-dioxide in tumor bearing mice

3-Amino-2-quinoxalincarbonitrile 1,4-dioxide (AQCD) is a quinoxaline derivative, which was synthesized by condensation method. AQCD was labeled with ^99mTc with labeling yield above 90% investigated by paper chromatography. ^99mTc-AQCD was prepared using stannous chloride as reducing agent at pH 7 and 10 min reaction time. ^99mTc-AQCD should be freshly prepared, otherwise the yield significantly decreased after 15 min post labeling. Stability study of ^99mTc-AQCD reflected the short time stability of Biodistribution study of ^99 mTc-AQCD in tumor bearing mice reflected that its uptake in tumor sites in both ascites and solid tumor sites. This uptake of ^99mTc-AQCD in tumor sites was sufficient to radioimage the inoculated sites.     

Diethylstilbestrol glucuronide (DESG): synthesis, labeling with radioiodine and in vivo/in vitro evaluations

Diethylstilbestrol (DES) is a synthetic non-steroidal estrogen, pharmacologic effects of which resemble natural estrons; today it is being used to treat some types of postmenopausal breast cancer and advanced prostate cancer. The aim of current study is conjugation of glucuronic acid (G) to DES and to evaluate radiopharmaceutical potential of this estrogen glucuronide derivative (DESG) which is specific to β glucuronidase enzyme consisting tumor cells. Taking into consideration the compatibility to the chemical structures of the synthesized product, ¹³¹I and ¹²⁵I were chosen as the appropriate radionuclides and DESG was labeled with these radionuclides utilizing iodogen method. The radiochemical yields of ^125/131I-DESG were over 90 % according to thin layer radio chromatography method. The biodistribution of ¹³¹I-DESG in healthy female Wistar Albino rats has been investigated and the range of the breast/blood and breast/muscle ratios were approximately 2 and 13 in 240 min for ER unsaturated studies. Effects of the radioiodinated DES and DESG on the cells were examined using MCF-7, A-549, Caco-2 cell lines. ¹²⁵I-DESG has higher incorporation percentages than ¹²⁵I-DES on MCF-7 cells. The radioiodinated DESG has the desired radiopharmaceutical properties which could be candidate radiopharmaceuticals for diagnosis and especially radionuclide therapy of breast tumors.     

Formulation of a freeze-dried kit for the preparation of <Superscript>99m</Superscript>Tc-tetrofosmin

A new formulation of a freeze-dried kit for the labeling of tetrofosmin with technetium-99m has been developed. The kit contains lyophilized mixture of 0.320 mg tetrofosmin [6,9-bis(2-ethoxyethyl)-3,12-dioxa-6,9-diphosphatetradecane], 0.025 mg stannous chloride dihydrate, 5 mg sodium tartrate and 5 mg sodium hydrogen carbonate. The product contains no antimicrobial preservative. When ^99mTc pertechnetate up to 6 mL saline containing 200 mCi is added to lyophilized mixture, a lipophilic, cationic ^99mTc complex is formed, ^99mTc-tetrofosmin. The performance of newly developed kit is compared with commercially available MYOVIEW kit for heart imaging. The patient studies show that the images of heart obtained by ^99mTc-tetrofosmin prepared by new formulation are equally good to MYOVIEW.     

Preliminary studies of 99mTc-PQQ-NMDAR binding and effect of specificity binding by mannitol

Pyrroloquinoline quinone (PQQ) is a powerful neuroprotectant that specifically binds to brain NMDA receptors and inhibits excitotoxicity. Imaging this binding reaction in the brain remains a long sought goal in this field of study, and one of the primary challenges remaining is enabling soluble labeled PQQ to pass the blood–brain barrier (BBB). Previously, our group successfully labeled PQQ with Technetium-99m (^99mTc), a metastable nuclear isomer used in radioactive isotope medical tests. In this work, we determined the specific binding of ^99mTc-PQQ and NMDAR by radioligand receptor assay. Ebselen (EB) and MK-801 both effectively inhibited ^99mTc-PQQ binding. We then investigated methods of opening the BBB using mannitol to enable entry to the brain by ^99mTc-PQQ. Our results showed that 7.5 mL/kg of 20 % mannitol effectively opened the BBB and 20 min was the optimum treatment time. Competition studies showed that mannitol did not affect the specific binding between ^99mTc-PQQ and NMDA receptors. Using this method, the amount of ^99mTc-PQQ uptake and retention was increased most significantly in the hippocampus and cortex, and re-opening the BBB did not affect binding. Together, our results demonstrate that the use of mannitol to open the BBB may contribute significantly to improving image quality by increasing the uptake amount of a water-soluble agent in brain.     

Reoxidation of uranium in electrolytically reduced simulated oxide fuel during residual salt distillation

Apoptosis is one of the fundamental phenomena behind successful radiation and chemotherapy treatments. Non-invasive imaging of apoptosis can offer an early diagnosis of disease and the true efficiency of an ongoing treatment procedure. The present study describes an attempt to develop ^99mTc-labeled 2-methyl-2-pentylmalonic acid ([^99mTc] 8) as a new SPECT based apoptosis imaging agent. An optimized chemical and radiosynthesis procedure provided desired product [^99mTc] 8 with high radiochemical yield (84%, n = 3) and radiochemical purity (>99%) as determined by radio HPLC. Biodistribution data indicated that the radiotracer has a rapid clearance from blood and other background tissues. High testes accumulation confirmed the ability of the radiotracer to detect testicular apoptosis in mice.