MRI and US imaging reveal evolution of spatial heterogeneity of murine tumor vasculature.

The tumor microenvironment, especially the vasculature, undergoes dynamic remodeling during tumor growth and progression. The aim of this study was to investigate changes in the structure and function of tumor microenvironment (TME), with a special focus on vasculature, during the growth of the Lewis Lung Carcinoma tumor (LLC). We have used several MRI techniques and ultrasound imaging of live animals to assess how heterogenous TME features change in time. Lewis lung carcinoma bearing C57BL/6 mice were examined for three weeks. During this time, assessment of tumor vasculature was performed with Time of Flight (TOF) angiography, Dynamic Contrast Enhanced (DCE) MRI and Power Doppler Ultrasound. Additionally, diffusion and perfusion were analyzed using Diffusion Weighted MRI (DWI). Consecutive measurements of the same animals revealed an approximately twofold decrease in the density of LLC vessels in time. Heterogeneity of vasculature was best uncovered by changes in histogram based DCE analysis and revealed deterioration of tumor vessels during its progression. The tumor vasculature became less dense and with slower blood flow, with larger and more permeable vessels. As a rule, tumor tissue perfusion and diffusion parameters decreased in time, but locally increase was observed. Time- and spatial heterogeneity of tumor microenvironment, including vasculature, was revealed by 3D imaging, demonstrating that local changes are often contradictory to parameters averaged over the whole tumor volume.

Hitchhiking Nanoparticles: Mesenchymal Stem Cell-Mediated Delivery of Theranostic Nanoparticles.

Nanotechnology has emerged as a promising solution to permanent elimination of cancer. However, nanoparticles themselves lack specificity to tumors. Due to enhanced migration to tumors, mesenchymal stem cells (MSCs) were suggested as cell-mediated delivery vehicles of nanoparticles. In this study, we have constructed a complex composed of photoluminescent quantum dots (QDs) and a photosensitizer chlorin e6 (Ce6) to obtain multifunctional nanoparticles, combining cancer diagnostic and therapeutic properties. QDs serve as energy donors-excited QDs transfer energy to the attached Ce6 via Förster resonance energy transfer, which in turn generates reactive oxygen species. Here, the physicochemical properties of the QD-Ce6 complex and singlet oxygen generation were measured, and the stability in protein-rich media was evaluated, showing that the complex remains the most stable in protein-free medium. In vitro studies on MSC and cancer cell response to the QD-Ce6 complex revealed the complex-loaded MSCs' potential to transport theranostic nanoparticles and induce cancer cell death. In vivo studies proved the therapeutic efficacy, as the survival of tumor-bearing mice was statistically significantly increased, while tumor progression and metastases were slowed down.

A Murine Bone Metastasis Model Using Caudal Artery Injection and Bioluminescence Imaging.

The current standard murine model of bone metastasis by using intracardiac injection (IC) has some limitations despite the great utility of this model. This fact emphasizes the need for a new murine model to accelerate basic research of bone metastasis. The present protocol provides instructions on caudal artery (CA) injection that is an easy-to-use method to reliably construct a murine bone metastasis model with a variety type of cancer cell lines. Bioluminescence imaging visualized that cancer cells injected via the caudal artery in the tail were efficiently delivered to a hind limb bone, where it is a common site affected with bone metastasis in mice. CA injection rarely causes stress-induced acute death in mice and enables us to inject a large number of cancer cells, thereby greatly increasing the frequency of bone metastasis in hind limb bones. Importantly, CA injection is technically as easy as tail vein injection and causes no lethal stress, indicating that it is a model that also contributes to animal welfare. CA injection model, therefore, could represent a powerful tool for many researchers to study molecular mechanisms of bone metastasis in mice.

In Vivo Imaging of Orthotopic Lung Cancer Models in Mice.

The success of anticancer interventions relies on their ability to ignite an anticancer immune response and to reinstate cancer immunosurveillance. Thus, high dose crizotinib can induce immunogenic cell death (ICD) in cancer cells. If combined with cisplatin, crizotinib sensitizes non-small cell lung cancers (NSCLC) to subsequent (but not simultaneous) immunotherapy with PD-1 immune checkpoint blockade, facilitating the cure of more than 90% of established orthotopic cancers in mice. Here, we detail protocols for the establishment and monitoring of transplantable orthotopic NSCLCs in syngeneic immunocompetent animals. Indeed, TC1 cells establish lung cancer upon their intravenous injection into the tail vein, while Lewis lung carcinoma (LLC) cells can be implanted intrathoracically to generate lung cancers. If transduced with luciferase, both TC1 and LLC cells form tumors that can be conveniently monitored by chemiluminescence. This type of NSCLC model is highly useful for the development of novel curative anticancer therapies.

In vivo study of anti-epidermal growth factor receptor antibody-based iron oxide nanoparticles (anti-EGFR-SPIONs) as a novel MR imaging contrast agent for lung cancer (LLC1) cells detection.

Superparamagnetic iron oxide nanoparticles (SPIONs) conjugated with anti-epidermal growth factor receptor monoclonal antibody (anti-EGFR-SPIONs) were characterised, and its cytotoxicity effects, ex vivo and in vivo studies on Lewis lung carcinoma (LLC1) cells in C57BL/6 mice were investigated. The broadband at 679.96 cm-1 relates to Fe-O, which verified the formation of the anti-EGFR-Mab with SPIONs was obtained by the FTIR. The TEM images showed spherical shape 20 and 80 nm-sized for nanoparticles and the anti-EGFR-SPIONs, respectively. Results of cell viability at 24 h after incubation with different concentrations of nanoprobe showed it has only a 20% reduction in cell viabilities. The synthesised nanoprobe administered by systemic injection into C57BL/6 mice showed good Fe tumour uptake and satisfied image signal intensity under ex vivo and in vivo conditions. A higher concentration of nanoprobe was achieved compared to non-specific and control, indicating selective delivery of nanoprobe to the tumour. It is concluded that the anti-EGFR-SPIONs was found to be as an MR imaging contrast nanoagent for lung cancer (LLC1) cells detection.

Improving tumor hypoxia and radiotherapy resistance via in situ nitric oxide release strategy.

Radiation therapy remains one of the main treatments for cancer. However, conventional radiotherapy not only manifests a low radiation accumulation in the tumor site, but also displays numerous negative effects. The most serious clinical problem is the radiotherapy resistance leading to cancer deterioration. As an important gaseous signal molecule, nitric oxide (NO) has been widely studied for its role in regulating angiogenesis, improving hypoxia, and inhibiting tumor growth. However, due to the unstable characteristic, the application of NO in cancer therapy is still limited. Here, we designed a micellar system formed by a NO donor, D-α-Tocopheryl polyethylene glycol 1000 succinate (TPGS)-NO, for enabling sustained NO release to efficiently deliver NO into the tumor area. TPGS-NO could accumulate in the tumor site for extended circulation, thereby releasing NO to exert antitumor effects and enhance radiotherapy effects under low-oxygen conditions. It demonstrated the increased sensitivity of radiotherapy through enhancing tumor angiogenesis appropriately reducing tumor area hypoxia, which significantly induced tumor cell apoptosis and inhibited its repair during radiation. This work may show great potential in synergistic radiotherapy against cancer by facile NO donor administration.

Cancer causes metabolic perturbations associated with reduced insulin-stimulated glucose uptake in peripheral tissues and impaired muscle microvascular perfusion.

BACKGROUND: Redirecting glucose from skeletal muscle and adipose tissue, likely benefits the tumor's energy demand to support tumor growth, as cancer patients with type 2 diabetes have 30% increased mortality rates. The aim of this study was to elucidate tissue-specific contributions and molecular mechanisms underlying cancer-induced metabolic perturbations. METHODS: Glucose uptake in skeletal muscle and white adipose tissue (WAT), as well as hepatic glucose production, were determined in control and Lewis lung carcinoma (LLC) tumor-bearing C57BL/6 mice using isotopic tracers. Skeletal muscle microvascular perfusion was analyzed via a real-time contrast-enhanced ultrasound technique. Finally, the role of fatty acid turnover on glycemic control was determined by treating tumor-bearing insulin-resistant mice with nicotinic acid or etomoxir. RESULTS: LLC tumor-bearing mice displayed reduced insulin-induced blood-glucose-lowering and glucose intolerance, which was restored by etomoxir or nicotinic acid. Insulin-stimulated glucose uptake was 30-40% reduced in skeletal muscle and WAT of mice carrying large tumors. Despite compromised glucose uptake, tumor-bearing mice displayed upregulated insulin-stimulated phosphorylation of TBC1D4Thr642 (+18%), AKTSer474 (+65%), and AKTThr309 (+86%) in muscle. Insulin caused a 70% increase in muscle microvascular perfusion in control mice, which was abolished in tumor-bearing mice. Additionally, tumor-bearing mice displayed increased (+45%) basal (not insulin-stimulated) hepatic glucose production. CONCLUSIONS: Cancer can result in marked perturbations on at least six metabolically essential functions; i) insulin's blood-glucose-lowering effect, ii) glucose tolerance, iii) skeletal muscle and WAT insulin-stimulated glucose uptake, iv) intramyocellular insulin signaling, v) muscle microvascular perfusion, and vi) basal hepatic glucose production in mice. The mechanism causing cancer-induced insulin resistance may relate to fatty acid metabolism.

Real-time fluorescence imaging for visualization and drug uptake prediction during drug delivery by thermosensitive liposomes.

Objective: Thermosensitive liposomal doxorubicin (TSL-Dox) is a promising stimuli-responsive nanoparticle drug delivery system that rapidly releases the contained drug in response to hyperthermia (HT) (>40 °C). Combined with localized heating, TSL-Dox allows highly localized delivery. The goals of this study were to demonstrate that real-time fluorescence imaging can visualize drug uptake during delivery, and can predict tumor drug uptake. Methods: Nude mice carrying subcutaneous tumors (Lewis lung carcinoma) were anesthetized and injected with TSL-Dox (5 mg/kg dose). Localized HT was induced by heating tumors for 15, 30 or 60 min via a custom-designed HT probe placed superficially at the tumor location. In vivo fluorescence imaging (excitation 523 nm, emission 610 nm) was performed before, during, and for 5 min following HT. After imaging, tumors were extracted, drug uptake was quantified by high-performance liquid chromatography, and correlated with in vivo fluorescence. Plasma samples were obtained before and after HT to measure TSL-Dox pharmacokinetics. Results: Local drug uptake could be visualized in real-time during HT. Compared to unheated control tumors, fluorescence of heated tumors increased by 4.6-fold (15 min HT), 9.3-fold (30 min HT), and 13.2-fold (60 min HT). HT duration predicted tumor drug uptake (p = .02), with tumor drug concentrations of 4.2 ± 1.3 µg/g (no HT), 7.1 ± 5.9 µg/g (15 min HT), 14.1 ± 6.7 µg/g (30 min HT) and 21.4 ± 12.6 µg/g (60 min HT). There was good correlation (R2 = 0.67) between fluorescence of the tumor region and tumor drug uptake. Conclusions: Real-time in vivo fluorescence imaging can visualize drug uptake during delivery, and can predict tumor drug uptake.

Fluorescence and Bioluminescence Imaging of Angiogenesis in Flk1-Nano-lantern Transgenic Mice.

Angiogenesis is important for normal development as well as for tumour growth. However, the molecular and cellular mechanisms underlying angiogenesis are not fully understood, partly because of the lack of a good animal model for imaging. Here, we report the generation of a novel transgenic (Tg) mouse that expresses a bioluminescent reporter protein, Nano-lantern, under the control of Fetal liver kinase 1 (Flk1). Flk1-Nano-lantern BAC Tg mice recapitulated endogenous Flk1 expression in endothelial cells and lymphatic endothelial cells during development and tumour growth. Importantly, bioluminescence imaging of endothelial cells from the aortic rings of Flk1-Nano-lantern BAC Tg mice enabled us to observe endothelial sprouting for 18 hr without any detectable phototoxicity. Furthermore, Flk1-Nano-lantern BAC Tg mice achieved time-lapse luminescence imaging of tumour angiogenesis in freely moving mice with implanted tumours. Thus, this transgenic mouse line contributes a unique model to study angiogenesis within both physiological and pathological contexts.

Heterogeneity of macrophage infiltration and therapeutic response in lung carcinoma revealed by 3D organ imaging.

Involvement of the immune system in tumour progression is at the forefront of cancer research. Analysis of the tumour immune microenvironment has yielded a wealth of information on tumour biology, and alterations in some immune subtypes, such as tumour-associated macrophages (TAM), can be strong prognostic indicators. Here, we use optical tissue clearing and a TAM-targeting injectable fluorescent nanoparticle (NP) to examine three-dimensional TAM composition, tumour-to-tumour heterogeneity, response to colony-stimulating factor 1 receptor (CSF-1R) blockade and nanoparticle-based drug delivery in murine pulmonary carcinoma. The method allows for rapid tumour volume assessment and spatial information on TAM infiltration at the cellular level in entire lungs. This method reveals that TAM density was heterogeneous across tumours in the same animal, overall TAM density is different among separate pulmonary tumour models, nanotherapeutic drug delivery correlated with TAM heterogeneity, and successful response to CSF-1R blockade is characterized by enhanced TAM penetration throughout and within tumours.

Quantification of tumor perfusion using dynamic contrast-enhanced ultrasound: impact of mathematical modeling.

Dynamic contrast-enhanced ultrasound has been proposed to monitor tumor therapy, as a complement to volume measurements. To assess the variability of perfusion parameters in ideal conditions, four consecutive test-retest studies were acquired in a mouse tumor model, using controlled injections. The impact of mathematical modeling on parameter variability was then investigated. Coefficients of variation (CV) of tissue blood volume (BV) and tissue blood flow (BF) based-parameters were estimated inside 32 sub-regions of the tumors, comparing the log-normal (LN) model with a one-compartment model fed by an arterial input function (AIF) and improved by the introduction of a time delay parameter. Relative perfusion parameters were also estimated by normalization of the LN parameters and normalization of the one-compartment parameters estimated with the AIF, using a reference tissue (RT) region. A direct estimation (rRTd) of relative parameters, based on the one-compartment model without using the AIF, was also obtained by using the kinetics inside the RT region. Results of test-retest studies show that absolute regional parameters have high CV, whatever the approach, with median values of about 30% for BV, and 40% for BF. The positive impact of normalization was established, showing a coherent estimation of relative parameters, with reduced CV (about 20% for BV and 30% for BF using the rRTd approach). These values were significantly lower (p < 0.05) than the CV of absolute parameters. The rRTd approach provided the smallest CV and should be preferred for estimating relative perfusion parameters.

Antiangiogenic Therapy Induces Hepatic Tumor Vascular Network Rearrangement to Receive Perfusion via the Portal Vein and Hepatic Artery.

PURPOSE: Hepatic malignancies can easily develop resistance to antiangiogenic therapy, but the underlying mechanism remains poorly understood. This study explores whether antiangiogenic therapy influences the tumor vascular network and/or the vessels feeding the hepatic tumor. METHODS: Mice implanted with Lewis lung carcinoma (LLC) cells were subcutaneously injected 3 times (once every other day starting 1 week after LLC implantation) with either an antiangiogenic agent [vascular endothelial growth factor (VEGF)-Trap] or control agent (bovine serum albumin) at a dose of 25 mg/kg before performing angiography. Hepatic arteriography and portography were performed using a vascular cast method with vascular latex. RESULTS: Arteriography of the control-treated LLC-implanted mice showed marked staining of the mass with a prominent feeding artery, suggesting that the tumor is supplied by arterial perfusion. No significant staining was observed on portography. By contrast, 33% (n = 3/9) of the LLC-implanted mice treated with the antiangiogenic agent VEGF-Trap showed intratumoral staining during portography, indicating that these tumors received perfusion via the portal vein. CONCLUSION: Antiangiogenic treatment can induce rearrangement of the hepatic tumor vascular network to establish communication with the portal vein. This implies that hepatic tumors can develop resistance to antiangiogenic therapy by maintaining perfusion through portal venous perfusion.

Stereotactic Comparison Study of (18)F-Alfatide and (18)F-FDG PET Imaging in an LLC Tumor-Bearing C57BL/6 Mouse Model.

This study aimed to stereotactically compare the PET imaging performance of (18)F-Alfatide ((18)F-ALF-NOTA-PRGD2, denoted as (18)F-Alfatide) and (18)F-fluorodeoxyglucose (FDG) and immunohistochemistry (IHC) staining in Lewis lung carcinoma (LLC) tumor-bearing C57BL/6 mouse model. (18)F-FDG standard uptake values (SUVs) were higher than (18)F-Alfatide SUVs in tumors, most of the normal tissues and organs except for the bladder. Tumor-to-brain, tumor-to-lung, and tumor-to-heart ratios of (18)F-Alfatide PET were significantly higher than those of (18)F-FDG PET (P < 0.001). The spatial heterogeneity of the tumors was detected, and the tracer accumulation enhanced from the outer layer to the inner layer consistently using the two tracers. The parameters of the tumors were significantly correlated with each other between (18)F-FDG SUV and GLUT-1 (R = 0.895, P < 0.001), (18)F-Alfatide SUV and αvß3 (R = 0.595, P = 0.019), (18)F-FDG SUV and (18)F-Alfatide SUV (R = 0.917, P < 0.001), and GLUT-1 and αvß3 (R = 0.637, P = 0.011). Therefore, (18)F-Alfatide PET may be an effective tracer for tumor detection, spatial heterogeneity imaging and an alternative supplement to (18)F-FDG PET, particularly for patients with enhanced characteristics in the brain, chest tumors or diabetes, meriting further study.

Tunable and amplified Raman gold nanoprobes for effective tracking (TARGET): in vivo sensing and imaging.

We describe the development of a highly tunable, physiologically stable, and ultra-bright Raman probe, named as TARGET (Tunable and Amplified Raman Gold Nanoprobes for Effective Tracking), for in vitro and in vivo surface-enhanced Raman scattering (SERS) applications. The TARGET structure consists of a gold core inside a larger gold shell with a tunable interstitial gap similar to a "nanorattle" structure. The combination of galvanic replacement and the seed mediated growth method was employed to load Raman reporter molecules and subsequently close the pores to prevent leaking and degradation of reporters under physiologically extreme conditions. Precise tuning of the core-shell gap width, core size, and shell thickness allows us to modulate the plasmonic effect and achieve a maximum electric-field (E-field) intensity. The interstitial gap of TARGET nanoprobes can be designed to exhibit a plasmon absorption band at 785 nm, which is in resonance with the dye absorption maximum and lies in the "tissue optical window", resulting in ultra-bright SERS signals for in vivo studies. The results of in vivo measurements of TARGETs in laboratory mice illustrated the usefulness of these nanoprobes for medical sensing and imaging.

Noninvasive Evaluation of Metabolic Tumor Volume in Lewis Lung Carcinoma Tumor-Bearing C57BL/6 Mice with Micro-PET and the Radiotracers 18F-Alfatide and 18F-FDG: A Comparative Analysis.

PURPOSE: To explore the value of a new simple lyophilized kit for labeling PRGD2 peptide (18F-ALF-NOTA-PRGD2, denoted as 18F-alfatide) in the determination of metabolic tumor volume (MTV) with micro-PET in lewis lung carcinoma (LLC) tumor-bearing C57BL/6 mice verified by pathologic examination and compared with those using 18F-fluorodeoxyglucose (FDG) PET. METHODS: All LLC tumor-bearing C57BL/6 mice underwent two attenuation-corrected whole-body micro-PET scans with the radiotracers 18F-alfatide and 18F-FDG within two days. 18F-alfatide metabolic tumor volume (VRGD) and 18F-FDG metabolic tumor volume (VFDG) were manually delineated slice by slice on PET images. Pathologic tumor volume (VPath) was measured in vitro after the xenografts were removed. RESULTS: A total of 37 mice with NSCLC xenografts were enrolled and 33 of them underwent 18F-alfatide PET, and 35 of them underwent 18F-FDG PET and all underwent pathological examination. The mean ± standard deviation of VPath, VRGD, and VFDG were 0.59±0.32 cm3 (range,0.13~1.64 cm3), 0.61±0.37 cm3 (range,0.15~1.86 cm3), and 1.24±0.53 cm3 (range,0.17~2.20 cm3), respectively. VPath vs. VRGD, VPath vs. VFDG, and VRGD vs. VFDG comparisons were t = -0.145, P = 0.885, t = -6.239, P<0.001, and t = -5.661, P<0.001, respectively. No significant difference was found between VPath and VRGD. VFDG was much larger than VRGD and VPath. VRGD seemed more approximate to the pathologic gross tumor volume. Furthermore, VPath was more strongly correlated with VRGD (R = 0.964,P<0.001) than with VFDG (R = 0.584,P<0.001). CONCLUSIONS: 18F-alfatide PET provided a better estimation of gross tumor volume than 18F-FDG PET in LLC tumor-bearing C57BL/6 mice.

Mouse Hepatic Tumor Vascular Imaging by Experimental Selective Angiography.

PURPOSE: Human hepatocellular carcinoma (HCC) has unique vascular features, which require selective imaging of hepatic arterial perfusion and portal venous perfusion with vascular catheterization for sufficient evaluation. Unlike in humans, vessels in mice are too small to catheterize, and the importance of separately imaging the feeding vessels of tumors is frequently overlooked in hepatic tumor models. The purpose of this study was to perform selective latex angiography in several mouse liver tumor models and assess their suitability. MATERIALS AND METHODS: In several ectopic (Lewis lung carcinoma, B16/F10 melanoma cell lines) and spontaneous liver tumor (Albumin-Cre/MST1fl/fl/MST2fl/fl, Albumin-Cre/WW45fl/fl, and H-ras12V genetically modified mouse) models, the heart left ventricle and/or main portal vein of mice was punctured, and latex dye was infused to achieve selective latex arteriography and/or portography. RESULTS: H-ras12V transgenic mice (a HCC and hepatic adenoma model) developed multiple liver nodules that displayed three different perfusion patterns (portal venous or hepatic artery perfusion predominant, mixed perfusion), indicating intra-tumoral vascular heterogeneity. Selective latex angiography revealed that the Lewis lung carcinoma implant model and the Albumin-Cre/WW45fl/fl model reproduced conventional angiography findings of human HCC. Specifically, these mice developed tumors with abundant feeding arteries but no portal venous perfusion. CONCLUSION: Different hepatic tumor models showed different tumor vessel characteristics that influence the suitability of the model and that should be considered when designing translational experiments. Selective latex angiography applied to certain mouse tumor models (both ectopic and spontaneous) closely simulated typical characteristics of human HCC vascular imaging.

Correlation of contrast-enhanced ultrasound with two distinct types of blood vessels for the assessment of angiogenesis in lewis lung carcinoma.

OBJECTIVE: The aim of our study was to evaluate tumor angiogenesis in Lewis lung carcinoma (LLC) of mice using a contrast-enhanced ultrasound (CEUS) examination, and to determine the correlation of contrast-enhanced ultrasonographic parameters with different blood vessel markers of microvessel density (MVD). MATERIALS AND METHODS: Subcutaneous Lewis lung carcinomas were established in 25 mice, which were evaluated by contrast-enhanced US using SonoVue (a second-generation US contrast agent). The results were recorded as digital video images and the time-intensity curves and hemodynamic parameters were analyzed. Pathological tumor specimens were obtained just after US examination. Tumor specimens were stained with hematoxylin and eosin (H & E) and expression of CD31 and CD34, the different endothelial cell markers, was determined by immunohistochemical straining. Then the relationship between the CEUS parameters and the level of MVD was analyzed. RESULTS: Two distinct types of microvessels were identified in Lewis lung carcinoma: differentiated (CD34 +) and undifferentiated (CD31 +) vessels. A significant correlation was found between CEUS parameters and undifferentiated MVD (CD31 + vessels) in LLC (P < 0.05). There was a reverse correlation between the different MVDs. CONCLUSION: The study showed that among the distinct types of vasculature (CD31 + and CD34 +) in Lewis lung carcinoma, the former correlated with the CEUS parameters. Therefore, CEUS using a second-generation US contrast agent may be useful for the evaluation of tumor angiogenesis of LLC of mice.

Hematopoietic stem and progenitor cell migration after hypofractionated radiation therapy in a murine model.

PURPOSE: To characterize the recruitment of bone marrow (BM)-derived hematopoietic stem and progenitor cells (HSPCs) within tumor microenvironment after radiation therapy (RT) in a murine, heterotopic tumor model. METHODS AND MATERIALS: Lewis lung carcinoma tumors were established in C57BL/6 mice and irradiated with 30 Gy given as 2 fractions over 2 days. Tumors were imaged with positron emission tomography/computed tomography (PET/CT) and measured daily with digital calipers. The HSPC and myelomonocytic cell content was assessed via immunofluorescent staining and flow cytometry. Functionality of tumor-associated HSPCs was verified in vitro using colony-forming cell assays and in vivo by rescuing lethally irradiated C57BL/6 recipients. RESULTS: Irradiation significantly reduced tumor volumes and tumor regrowth rates compared with nonirradiated controls. The number of CD133(+) HSPCs present in irradiated tumors was higher than in nonirradiated tumors during all stages of regrowth. CD11b(+) counts were similar. PET/CT imaging and growth rate analysis based on standardized uptake value indicated that HSPC recruitment directly correlated to the extent of regrowth and intratumor cell activity after irradiation. The BM-derived tumor-associated HSPCs successfully formed hematopoietic colonies and engrafted irradiated mice. Finally, targeted treatment with a small animal radiation research platform demonstrated localized HSPC recruitment to defined tumor subsites exposed to radiation. CONCLUSIONS: Hypofractionated irradiation resulted in a pronounced and targeted recruitment of BM-derived HSPCs, possibly as a mechanism to promote tumor regrowth. These data indicate for the first time that radiation therapy regulates HSPC content within regrowing tumors.

Development of a new positron emission tomography tracer for targeting tumor angiogenesis: synthesis, small animal imaging, and radiation dosimetry.

Angiogenesis plays a key role in cancer progression and correlates with disease aggressiveness and poor clinical outcomes. Affinity ligands discovered by screening phage display random peptide libraries can be engineered to molecularly target tumor blood vessels for noninvasive imaging and early detection of tumor aggressiveness. In this study, we tested the ability of a phage-display-selected peptide sequence recognizing specifically bone marrow- derived pro-angiogenic tumor-homing cells, the QFP-peptide, radiolabeled with 64Cu radioisotope to selectively image tumor vasculature in vivo by positron emission tomography (PET). To prepare the targeted PET tracer we modified QFP-phage with the DOTA chelator and radiolabeled the purified QFP-phage-DOTA intermediate with 64Cu to obtain QFP-targeted radioconjugate with high radiopharmaceutical yield and specific activity. We evaluated the new PET tracer in vivo in a subcutaneous (s.c.) Lewis lung carcinoma (LLC) mouse model and conducted tissue distribution, small animal PET/CT imaging study, autoradiography, histology, fluorescence imaging, and dosimetry assessments. The results from this study show that, in the context of the s.c. LLC immunocompetent mouse model, the QFP-tracer can target tumor blood vessels selectively. However, further optimization of the biodistribution and dosimetry profile of the tracer is necessary to ensure efficient radiopharmaceutical applications enabled by the biological specificity of the QFP-peptide.

A study of 131iodine-labeling of histamine-indomethacin: its in vivo therapeutic effect and anti-tumor mechanisms in Lewis-bearing lung cancer.

BACKGROUND: In our research,we study the effect of 131iodine-labeled histamine-indomethacin (131I-His-IN). We focus on its in vivo therapeutic effect and anti-tumor mechanisms in Lewis-bearing lung cancer. METHODS: 131I-His-IN was administered by garage to the mice. At different timepoints, we made autoradiography (ARG) slices to observe the distribution of 131I-His-IN in the cellular, and the sliced samples underwent hematoxylin and eosin (HE) staining for observation of tumor necrosis. Before treatment, the groups of mice underwent 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) scans ,and they were then given physiologic saline, iodine 131 (131I), indomethacin (IN), Histamine-indomethacin (His-IN), and 131I-His-IN, respectively, three times daily for seven days. Seven days later, all the mice underwent 18F-FDG PET-CT scans again. We calculated the maximum standard uptake value (SUVmax) of the region of interest (ROI) and tumor inhibition rate at the same time. RESULTS: In ARG groups, black silver particle was concentrated in the nucleus and cytoplasm. 131I-His-IN mainly concentrated in tumor tissues. At 8 hours after 131I-His-IN, the radioactivity uptake in tumor tissue was higher than in other organs (F=3.46, P<0.05). For the 18F-FDG PET-CT imaging, the tumor tissuses SUVmax of the ROI was lower compared to other groups after the treatment with 131I-His-IN. The tumor inhibitory rate (54.8%) in 131I-His-IN group was higher than in other groups, too. In the 131I-His-IN group the vascular endothelial growth factor (VEGF) decreased gradually compared to other groups. The tumor tissue necrotized obviously in 131I-His-IN group. CONCLUSIONS: Through these animal experiments, we found 131I-His-IN could inhibit the Lewis lung cancer cells. 131I-His-IN focused at the cell nucleus and cytoplasm. It could reduce VEGF and increase tumor inhibitory rate. At the same time, 18F-FDG PET-CT scan could be used for a curative effect and monitoring of disease prognosis.