Human Colon Adenocarcinoma Xenografts Research Articles

Inhibition of Transketolase Improves the Prognosis of Colorectal Cancer.

Colorectal cancer (CRC) remains a heavy health burden worldwide. Transketolase (TKT) is a crucial enzyme in the non-oxidative phase of the Pentose Phosphate Pathway (PPP), and is up-regulated in multiple cancer types. However, the role of TKT in the prognosis of CRC remains unclear. We aimed to explore whether TKT expression is altered in CRC, how TKT is associated with the prognosis of CRC, and whether the regulation of TKT might have an impact on CRC. Differentially expressed genes (DEGs) were identified using bioinformatics analysis. TKT expression was examined in the human colon adenocarcinoma tissue microarray and xenografts. Cell viability, proliferation, migration, and apoptosis assays in vitro were applied to evaluate the protumoral effects of TKT on CRC. TKT was found to be a risk factor for the poor prognosis of CRC by bioinformatics analysis among the DEGs. TKT was significantly up-regulated in colon adenocarcinoma tissues compared with normal colon tissues in patients. Moreover, similar results were found in HCT116 and RKO human colon adenocarcinoma xenografts in nude mice. TKT expression was positively associated with advanced TNM stage, positive lymph nodes, and poor 5 or 10-year overall survival of CRC patients. In vitro, inhibition of TKT reduced cell viability, proliferation, and migration, and induced cell apoptosis. In addition, inhibition of TKT decreased the protein levels of NICD and Hes1. In conclusion, high TKT expression was associated with the poor prognosis of CRC patients. The protumoral effects of downregulating TKT may be realized by suppressing the Notch signaling pathway. TKT may be a new prognostic biomarker and therapeutic target for CRC.

A Study of Microvascular Density in Carcinoma of Breast with CD34 Immunostaining

Introduction: Tumor agiogenesis is generally classified in to two types, namely, sprouting and intussusceptive angiogenesis. The formation of new blood vessels from the already existing is termed as sprouting angiogenesis. Many growth factors including endothelial growth factor (VEGF) contribute the formation of new vessels at the tumor sites. On other hand, the tumor able to split the existing blood vessels, this type is termed as intussuscepted angiogenesis and discovered in human colon adenocarcinoma xenograft. In intussuscepted angiogenesis, an existing blood vessel splits into two new blood vessels by formation of trans vascular pillars.
 Objective: The present study aimed to analyse the nicrovascular density on breast cancer patients using CD 34 immunostaining method.
 Results: This mis-regulation may lead to the development of cancers. Histological grading with Grade II were more with 19 (63.3%) cases followed by Grade I with 4 (13.3%) and Grade III with 3 (10%) cases. There was increase in mean vascular density in Grade II when compared with Grade I and Grade III. However no significant correlation was observed statistically with a P value of 0.176. Using different antibodies such as CD34, CD31, Factor VIII and CD105 to microvessels differentiation was highlighted.
 Conclusion: The results showed that the anti-CD34 monoclonal antibody is more sensitive than the anti- CD31 antibody in calculation of MVD in breast cancer as mentioned in previous studies.

Aminosilanized flower-structured superparamagnetic iron oxide nanoparticles coupled to 131I-labeled CC49 antibody for combined radionuclide and hyperthermia therapy of cancer

Combined radionuclide therapy with magnetic nanoparticles-mediated hyperthermia has been under research focus as a promising tumor therapy approach. The objective of this study was to investigate the potential of 131I-radiolabeled superparamagnetic iron oxide nanoparticles (SPIONs) prepared as the ~40nm flower-shaped structures with excellent heating efficiency (specific absorption rate at H0=15.9 kA∙m-1 and resonant frequency of 252kHz was 123.1W∙g-1) for nano-brachytherapy of tumors. 131I-radiolabeled CC49 antibody attached to SPIONs via reactive groups of 3-aminopropyltriethoxysilane (APTES) provided specificity and long-lasting localized retention after their intratumoral application into LS174T human colon adenocarcinoma xenografts in NOD-SCID mice. The results demonstrate feasibility and effectiveness of magnetic hyperthermia (HT), radionuclide therapy (RT) and their combination (HT+RT) in treating cancer in xenograft models. Combined therapy approach induced a significant (p<0.01) tumor growth suppression in comparison to untreated groups presented by the tumor volume inhibitory rate (TVIR): 54.38%, 68.77%, 73.00% for HT, RT and HT+RT, respectively in comparison to untreated group and 48.31%, 64,62% and 69,41%, respectively, for the SPIONs-only injected group. Histopathology analysis proved the necrosis and apoptosis in treated tumors without general toxicity. Obtained data support the idea that nano-brachytherapy combined with hyperthermia is a promising approach for effective cancer treatment.

Colonization of xenograft tumors by oncolytic vaccinia virus (VACV) results in enhanced tumor killing due to the involvement of myeloid cells.

BackgroundThe mechanisms by which vaccinia virus (VACV) interacts with the innate immune components are complex and involve different mechanisms. iNOS-mediated NO production by myeloid cells is one of the central antiviral mechanisms and this study aims to investigate specifically whether iNOS-mediated NO production by myeloid cells, is involved in tumor eradication following the virus treatment.MethodsHuman colon adenocarcinoma (HCT-116) xenograft tumors were infected by VACV. Infiltration of iNOS+ myeloid cell population into the tumor, and virus titer was monitored following the treatment. Single-cell suspensions were stained for qualitative and quantitative flow analysis. The effect of different myeloid cell subsets on tumor growth and colonization were investigated by depletion studies. Finally, in vitro culture experiments were carried out to study NO production and tumor cell killing. Student’s t test was used for comparison between groups in all of the experiments.ResultsInfection of human colon adenocarcinoma (HCT-116) xenograft tumors by VACV has led to recruitment of many CD11b+ ly6G+ myeloid-derived suppressor cells (MDSCs), with enhanced iNOS expression in the tumors, and to an increased intratumoral virus titer between days 7 and 10 post-VACV therapy. In parallel, both single and multiple rounds of iNOS-producing cell depletions caused very rapid tumor growth within the same period after virus injection, indicating that VACV-induced iNOS+ MDSCs could be an important antitumor effector component. A continuous blockade of iNOS by its specific inhibitor, L-NIL, showed similar tumor growth enhancement 7–10 days post-infection. Finally, spleen-derived iNOS+ MDSCs isolated from virus-injected tumor bearing mice produced higher amounts of NO and effectively killed HCT-116 cells in in vitro transwell experiments.ConclusionsWe initially hypothesized that NO could be one of the factors that limits active spreading of the virus in the cancerous tissue. In contrast to our initial hypothesis, we observed that PMN-MDSCs were the main producer of NO through iNOS and NO provided a beneficial antitumor effect, The results strongly support an important novel role for VACV infection in the tumor microenvironment. VACV convert tumor-promoting MDSCs into tumor-killing cells by inducing higher NO production.

SPECT/NIRF Dual Modality Imaging for Detection of Intraperitoneal Colon Tumor with an Avidin/Biotin Pretargeting System.

We describe herein dual-modality imaging of intraperitoneal colon tumor using an avidin/biotin pretargeting system. A novel dual-modality probe, 99mTc-HYNIC-lys(Cy5.5)-PEG4-biotin, was designed, synthesized and characterized. Single-photon emission computed tomography/ computed tomography (SPECT/CT) imaging and near infrared fluorescence (NIRF) imaging were developed using intraperitoneal LS180 human colon adenocarcinoma xenografts. Following avidin preinjection for 4 hours, 99mTc-HYNIC-lys(Cy5.5)-PEG4-biotin could successfully detect colon tumors of different sizes inside the abdominal region using both modalities, and the imaging results showed no differences. Biodistribution studies demonstrated that the tumors had a very high uptake of the probe 99mTc-HYNIC-lys(Cy5.5)-PEG4-biotin (12.74 ± 1.89% ID/g at 2 h p.i.), and the clearance from blood and other normal tissues occured very fast. The low tumor uptake in the non-pretargeted mice (1.63 ± 0.50% ID/g at 2 h p.i.) and tumor cell staining results showed excellent tumor binding specificity of the pretargeting system. The ability of the novel probe to show excellent imaging quality with high tumor-to-background contrast, a high degree of binding specificity with tumors and excellent in vivo biodistribution pharmacokinetics should prove that the avidin/biotin based dual-modality pretargeting probe is a promising imaging tool during the entire period of tumor diagnosis and treatment.

Phosphonooxymethyl Prodrug of Triptolide: Synthesis, Physicochemical Characterization, and Efficacy in Human Colon Adenocarcinoma and Ovarian Cancer Xenografts.

A disodium phosphonooxymethyl prodrug of the antitumor agent triptolide was prepared from the natural product in three steps (39% yield) and displayed excellent aqueous solubility at pH 7.4 (61 mg/mL) compared to the natural product (17 μg/mL). The estimated shelf life (t90) for hydrolysis of the prodrug at 4 °C and pH 7.4 was found to be two years. In a mouse model of human colon adenocarcinoma (HT-29), the prodrug administered intraperitoneally was effective in reducing or eliminating xenograft tumors at dose levels as low as 0.3 mg/kg when given daily and at 0.9 mg/kg when given less frequently. When given via intraperitoneal and oral routes at daily doses of 0.6 and 0.9 mg/kg, the prodrug was also effective and well tolerated in a mouse model of human ovarian cancer (A2780).

Potentiation of the activity of cisplatin in a human colon tumour xenograft model by auristatin PYE, a structural modification of dolastatin 10.

Dolastatin 10, a marine natural product peptide, is now known to act as a vascular disrupting agent (VDA). These VDA properties were not known when other aspects of its promising pre-clinical profile led to initial unsuccessful clinical trials. Auristatin PYE, a synthetic analogue of dolastatin 10, has demonstrated improved activity in preliminary in vivo studies. However, as with other VDAs, tumour eradication was incomplete due to the maintenance of functional vasculature supporting the viable tumour at the periphery of the tumour xenograft, meaning that once the VDA effect subsides, the tumour regrows. One possible strategy for removing this peripheral tumour involves combining VDA therapy with another anticancer drug with a different mechanism of action. Here, we evaluated the effect of combining auristatin PYE with cisplatin in an HCT-116 human colon adenocarcinoma xenograft model. The effects on the growth of subcutaneously implanted HCT-116 xenografts in mice following intraperitoneal administration of a single dose of 4 mgkg-1 cisplatin and intravenous administration of 1 mgkg-1 auristatin PYE were evaluated compared to the effect of each agent administered alone. The effects on the functional tumour vasculature were also assessed. Statistically significant potentiation (p<0.01) was noted with a 465% growth delay for the combination group compared to the control, and 142 and 310% growth delays for the cisplatin and auristatin PYE groups, respectively. Shut down of tumour vasculature in the combination group was similar to that observed with auristatin PYE on its own. Auristatin PYE demonstrated synergistic antitumour effects when combined with cisplatin, suggesting that a combination chemotherapy regimen would be the most effective strategy when applying this new anticancer drug.

Evaluation of Glycodendron and Synthetically Modified Dextran Clearing Agents for Multistep Targeting of Radioisotopes for Molecular Imaging and Radioimmunotherapy

A series of N-acetylgalactosamine-dendrons (NAG-dendrons) and dextrans bearing biotin moieties were compared for their ability to complex with and sequester circulating bispecific antitumor antibody streptavidin fusion protein (scFv4-SA) in vivo, to improve tumor-to-normal tissue concentration ratios for multistep targeted (MST) radioimmunotherapy and diagnosis. Specifically, a total of five NAG-dendrons employing a common synthetic scaffold structure containing 4, 8, 16, or 32 carbohydrate residues and a single biotin moiety were prepared (NAGB), and for comparative purposes, a biotinylated-dextran with an average molecular weight of 500 kD was synthesized from amino-dextran (DEXB). One of the NAGB compounds, CA16, has been investigated in humans; our aim was to determine if other NAGB analogues (e.g., CA8 or CA4) were bioequivalent to CA16 and/or better suited as MST reagents. In vivo studies included dynamic positron-emission tomography (PET) imaging of (124)I-labeled-scFv4-SA clearance and dual-label biodistribution studies following MST directed at subcutaneous (s.c.) human colon adenocarcinoma xenografts in mice. The MST protocol consists of three injections: first, a scFv4-SA specific for an antitumor-associated glycoprotein (TAG-72); second, CA16 or other clearing agent; and third, radiolabeled biotin. We observed using PET imaging of the (124)I-labeled-scFv4-SA clearance that the spatial arrangement of ligands conjugated to NAG (i.e., biotin linked with an extended spacer, referred to herein as long-chain (LC)) can impact the binding to the antibody in circulation and subsequent liver uptake of the NAG-antibody complex. Also, NAGB CA32-LC or CA16-LC can be utilized during MST to achieve comparable tumor-to-blood ratios and absolute tumor uptake seen previously with CA16. Finally, DEXB was equally effective as NAGB CA32-LC at lowering scFv4-SA in circulation, but at the expense of reducing absolute tumor uptake of radiolabeled biotin.

Aldose Reductase Inhibition Prevents Colon Cancer Growth by Restoring Phosphatase and Tensin Homolog Through Modulation of miR-21 and FOXO3a

We have shown earlier that inhibition of aldose reductase (AR), an oxidative stress-response protein, prevents colon cancer cell growth in vitro and in vivo. Changes in microribonucleic acid (miR) expression can contribute to cancer by modulating the functional expression of critical genes involved in cancer growth and metastasis. However, the molecular mechanisms by which AR regulates miR expression and their dependent mitogenic effects in cancer cells are not known. Therefore, we investigated how AR regulates growth factor-induced expression of miRs and growth of colon cancer cells. Inhibition of AR significantly downregulated growth factor-induced miR-21 expression in human colon cancer cells, HT29, SW480, and Caco-2. Further, AR inhibition also increased phosphatase and tensin homolog (PTEN) (a direct target of miR-21) and forkhead box O3A (FOXO3a) in colon cancer cells. Our results obtained with HT29 cells ablated with FOXO3a siRNA showed increased activator protein-1 (AP-1) activation and miR-21 expression, indicating that FOXO3a represses miR-21 via AP-1 inactivation. Inhibition of AR also prevented the epidermal growth factor-induced phosphorylation of phosphatidylinositol 3-kinase (PI3K), serine/threonine kinase (AKT), c-Jun, c-Fos, PTEN, and FOXO3a, and deoxyribonucleic acid (DNA)-binding activity of AP-1. More importantly, in human colon adenocarcinoma xenograft tissues, miR-21 expression was lower, and PTEN and FOXO3a levels were significantly higher in AR inhibitor-treated mice compared to controls. These findings demonstrate a novel role of AR in the regulation of miR-21 and its target PTEN in growth factor-induced colon cancer cell growth. Collectively, these results show a novel role of AR in mediation of growth factor-induced colon cancer growth by modulating miR-21, PTEN, and FOXO3a expression through reactive oxygen species (ROS)/PI3K/AKT/AP-1.

Abstract 2296: Aldose reductase inhibition prevents human colon cancer cells growth by miR-21 and FOXO3a-mediated regulation of PTEN

Abstract We have shown earlier that the inhibition of aldose reductase (AR), a NADPH-dependent aldo-keto reductase, prevents growth factor-induced proliferation of colon cancer cells in vitro and in vivo. Recent studies indicate that changes in microRNA (miRNA) expression can contribute to cancer by modulating the functional expression of critical genes involved in cancer growth and metastasis. However, the molecular mechanism(s) by which AR regulates miRNA expression and their dependent mitogenic effects in cancer cells is not known. Therefore, we investigated how AR regulates growth factor -induced expression of miRNAs in colon cancer cells. Our results indicate that inhibition of AR significantly down-regulated growth factor-induced miR-21 expression in HT29, SW480 and Caco-2 human colon cancer cells. Further, AR inhibition also increased PTEN, a direct target of miR-21 that contributes cancer cell growth and invasion. Inhibition of AR also prevented the EGF-induced phosphorylation of PTEN and FOXO3a, which prevents cell proliferation. Treatment of human colon cancer cells with AR inhibitor, fidarestat, prevented the EGF-induced DNA binding activity of AP1, phosphorylation of PI3K, AKT, c-Jun and c-Fos. More importantly, in HT29 human colon adenocarcinoma xenograft tissues, miR-21 expression was lower, and PTEN and FOXO3a levels were significantly higher in AR inhibitor-treated mice compared to controls. Collectively, these results show a novel role of AR in mediation of growth factor-induced colon cancer cell proliferation by increasing miR-21 expression and inactivating or decreasing PTEN and FOXO3a through the ROS/PI3K/AKT/AP1 pathway, indicating that AR inhibitors could be used for the prevention/therapy of colon carcinogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2296. doi:1538-7445.AM2012-2296

NMS-P937, an Orally Available, Specific Small-Molecule Polo-like Kinase 1 Inhibitor with Antitumor Activity in Solid and Hematologic Malignancies

Polo-like kinase 1 (PLK1) is a serine/threonine protein kinase considered to be the master player of cell-cycle regulation during mitosis. It is indeed involved in centrosome maturation, bipolar spindle formation, chromosome separation, and cytokinesis. PLK1 is overexpressed in a variety of human tumors and its overexpression often correlates with poor prognosis. Although five different PLKs are described in humans, depletion or inhibition of kinase activity of PLK1 is sufficient to induce cell-cycle arrest and apoptosis in cancer cell lines and in xenograft tumor models. NMS-P937 is a novel, orally available PLK1-specific inhibitor. The compound shows high potency in proliferation assays having low nanomolar activity on a large number of cell lines, both from solid and hematologic tumors. NMS-P937 potently causes a mitotic cell-cycle arrest followed by apoptosis in cancer cell lines and inhibits xenograft tumor growth with clear PLK1-related mechanism of action at well-tolerated doses in mice after oral administration. In addition, NMS-P937 shows potential for combination in clinical settings with approved cytotoxic drugs, causing tumor regression in HT29 human colon adenocarcinoma xenografts upon combination with irinotecan and prolonged survival of animals in a disseminated model of acute myelogenous leukemia in combination with cytarabine. NMS-P937, with its favorable pharmacologic parameters, good oral bioavailability in rodent and nonrodent species, and proven antitumor activity in different preclinical models using a variety of dosing regimens, potentially provides a high degree of flexibility in dosing schedules and warrants investigation in clinical settings.

A Dual-radiolabel Marker Quantifies Decrease in HT29 Xenograft Hypoxia Induced by Mild Temperature Hyperthermia

Purpose: In this project, we developed novel methods to quantify changes in tumor hypoxia following a mild tempera-ture hyperthermia (MTH) treatment in rat HT29 human colon adenocarcinoma xenograft. Materials and Methods: An exogenous hypoxia marker (IAZGP) was labeled with two radioisotopes of iodine (131I and 123I, respectively) to form two distinct tracers. The two tracers were injected into HT29-bearing nude rats 4-hour before and immediately following 41.5℃, 45-minute mild hyperthermia treatment. The distributions of the two hypoxia tracers were obtained by performing digital autoradiography on tumor sections, and image processing resulted in quantitative information at 50 μm pixel size. Results: Following the hyperthermia treatment, there was a remarkable decrease in hypoxia tracer binding. The average whole tumor hypoxia tracer targeted fraction in five animals changed from 30.3% ± 9.7% to 13.0% ± 5.3% after the hyperthermia treatment (P = 0.001). Detailed pixelby-pixel analysis of the image data revealed a decline in hypoxia tracer uptake after hyperthermia in most regions. However, there was concomitant emergence of some new regions of hypoxia identified by increased tracer uptake. In the control group, the overall hypoxia tracer targeted fraction remained almost constant, with some hypoxic tracer redistribution (putative acute hypoxia) observed. Conclusion: Reoxygenation occurred in the rat HT29 xenograft following MTH treatment. This was evident with preponderance of decreased hypoxia specific tracer uptake on tumor sections. Our methodology might be a useful tool in hypoxia study.

A New Mechanism for Pillar Formation during Tumor-Induced Intussusceptive Angiogenesis: Inverse Sprouting

One of the hallmarks of intussusceptive angiogenesis is the development of intraluminal connective tissue pillars. The exact mechanism of pillar formation has not yet been elucidated. By using electron and confocal microscopy, we observed intraluminal nascent pillars that contain a collagen bundle covered by endothelial cells (ECs) in the vasculature of experimental tumors. We proposed a new mechanism for the development of these pillars. First, intraluminal endothelial bridges are formed. Second, localized dissolution of the basement membrane occurs and a bridging EC attaches to a collagen bundle in the underlying connective tissue. A pulling force is then exerted by the actin cytoskeleton of the ECs via specific attachment points, which contain vinculin, to the collagen bundle, resulting in suction and subsequent transport of the collagen bundle into and through the vessel lumen. Third, the pillar matures through the immigration of connective tissue cells and the deposition of new collagenous connective tissue. The proposed simple mechanism generates a connection between the processes of endothelial bridging and intussusceptive angiogenesis and identifies the source of the force behind pillar formation. Moreover, it ensures the rapid formation of pillars from pre-existing building blocks and the maintenance of EC polarity. To describe it, we coined the term inverse sprouting.

Abstract 5245: Regional analysis of DCE MR images to unravel tumor growth and response heterogeneity in SW-620 human colon adenocarcinoma xenografts

Abstract Introduction: Dynamic Contrast-Enhanced (DCE) MRI, a clinically relevant technique used to assess response to anti-angiogenic therapies, relies on imaging of a T1 modifying contrast agent to characterize vascular response by the dynamics of tracer exchange between the vessels and the interstitial space. The parameter Ktrans is a measure of the tumor vascular permeability, vascular surface area and blood flow, and is normally assessed as mean over the entire tumor volume. Generally, decreasing tumor mean Ktrans occurs after effective vascular targeting. However, localized tumor growth based necrosis/under-perfusion can also lower Ktrans, leading to uncoupling of the endpoint from the effect. Techniques that can overcome confounding effects of heterogeneity may improve Ktrans sensitivity and correlation with outcome. We applied a thresholding technique to Ktrans data to analyze regional Ktrans variations in subcutaneous SW-620 tumors treated with the vascular targeted agent, bevacizumab or vehicle. Materials and Methods: Female nu/nu mice were implanted with SW-620 tumor fragments on Day 0. On Day 14, mice were distributed into groups with matching tumor burden. DCE-MRI images were acquired 24 hours before treatment (vehicle or bevacizumab; IP; 5mg/kg; Q3Dx4), and one week after treatment. The data were fitted to a Tofts-Kermode kinetic model to generate Ktrans over the entire tumor volume. Thresholds we determined by pooling all the Ktransvalues from the pre-treatment DCE MRI scans. The Ktrans values for each image were distributed into low, mid and high Ktrans fractions and the percentage of voxels in each fraction was calculated. Results: Bevacusimab resulted in moderate tumor growth inhibition (T/C = 43% on Day 22). Tumor mean Ktrans one week post-treatment start did not correlate with this effect, with Ktrans (T/C) = 131%. Analysis of location of voxels in the low, mid and high Ktrans fractions in the pre-treatment images showed that lower Ktrans values were generally confined to the tumor core, while higher Ktrans values were generally confined to the tumor periphery. These regions presumably related to under-perfused (core) and well perfused (periphery) tissue. A comparison of the high Ktrans volume fractions one week post-treatment (treated vs control) showed a correlation with the growth based treatment effect (high Ktrans volume fraction (T/C) = 44%). Ktrans thresholding may therefore provide a means to increasing sensitivity to treatment-based vascular inhibition. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5245.

Potentiation of the activity of cisplatin in a human colon tumour xenograft model by auristatin PYE, a structural modification of dolastatin 10

Dolastatin 10, a marine natural product peptide, is now known to act as a vascular disrupting agent (VDA). These VDA properties were not known when other aspects of its promising pre-clinical profile led to initial unsuccessful clinical trials. Auristatin PYE, a synthetic analogue of dolastatin 10, has demonstrated improved activity in preliminary in vivo studies. However, as with other VDAs, tumour eradication was incomplete due to the maintenance of functional vasculature supporting the viable tumour at the periphery of the tumour xenograft, meaning that once the VDA effect subsides, the tumour regrows. One possible strategy for removing this peripheral tumour involves combining VDA therapy with another anticancer drug with a different mechanism of action. Here, we evaluated the effect of combining auristatin PYE with cisplatin in an HCT-116 human colon adenocarcinoma xenograft model. The effects on the growth of subcutaneously implanted HCT-116 xenografts in mice following intraperitoneal administration of a single dose of 4 mgkg−1 cisplatin and intravenous administration of 1 mgkg−1 auristatin PYE were evaluated compared to the effect of each agent administered alone. The effects on the functional tumour vasculature were also assessed. Statistically significant potentiation (p<0.01) was noted with a 465% growth delay for the combination group compared to the control, and 142 and 310% growth delays for the cisplatin and auristatin PYE groups, respectively. Shut down of tumour vasculature in the combination group was similar to that observed with auristatin PYE on its own. Auristatin PYE demonstrated synergistic antitumour effects when combined with cisplatin, suggesting that a combination chemotherapy regimen would be the most effective strategy when applying this new anticancer drug.

Compensation of optical heterogeneity-induced artifacts in fluorescence molecular tomography: theory and in vivo validation

We present a method for reduction of image artifacts induced by the optical heterogeneities of tissue in fluorescence molecular tomography (FMT) through identification and compensation of image regions that evidence propagation of emission light through thin or low-absorption tunnels in tissue. The light tunneled as such contributes to the emission image as spurious components that might substantially overwhelm the desirable fluorescence emanating from the targeted lesions. The proposed method makes use of the strong spatial correlation between the emission and excitation images to estimate the tunneled components and yield a residual image that mainly consists of the signal due to the desirable fluorescence. This residual image is further refined using a coincidence mask constructed for each excitation-emission image pair. The coincidence mask is essentially a map of the "hot spots" that occur in both excitation and emission images, as such areas are often associated with tunneled emission. In vivo studies are performed on a human colon adenocarcinoma xenograft tumor model with subcutaneous tumors and a murine breast adenocarcinoma model with aggressive tumor cell metastasis and growth in the lungs. Results demonstrate significant improvements in the reconstructions achieved by the proposed method.

Naphthamides as Novel and Potent Vascular Endothelial Growth Factor Receptor Tyrosine Kinase Inhibitors: Design, Synthesis, and Evaluation

A series of naphthyl-based compounds were synthesized as potential inhibitors of vascular endothelial growth factor (VEGF) receptors. Investigations of structure-activity relationships led to the identification of a series of naphthamides that are potent inhibitors of the VEGF receptor tyrosine kinase family. Numerous analogues demonstrated low nanomolar inhibition of VEGF-dependent human umbilical vein endothelial cell (HUVEC) proliferation, and of these several compounds possessed favorable pharmacokinetic (PK) profiles. In particular, compound 48 demonstrated significant antitumor efficacy against established HT29 human colon adenocarcinoma xenografts implanted in athymic mice. A full account of the preparation, structure-activity relationships, pharmacokinetic properties, and pharmacology of analogues within this series is presented.

Photodynamic therapy with di- l-arginine protoporphyrinate on WiDr human colon adenocarcinoma xenografts in athymic nude mice

The fluorescence kinetics of a new photosensitizer for photodynamic therapy, di-l-arginine protoporphyrinate (PP(Arg)2), was studied in the skin of healthy mice. Furthermore, induction of necrosis in WiDr human colon adenocarcinoma xenografts in athymic nude mice was studied after photodynamic therapy (PDT) with PP(Arg)2. After intravenous administration of PP(Arg)2 maximal fluorescence was reached after 72h in normal mouse skin. Complete elimination of the drug from the mouse skin was not found even after 32 days. Exposure of WiDr tumours in mice to red light (λ=632nm, fluence 150J/cm(2), fluence rate 250mW/cm(2)) 24 and 72h after intravenous administration of 10mg/kg of PP(Arg)2 caused extensive tumour necrosis. Epidermal damage and infiltration of inflammatory cells was seen 24h after light exposure but not after 72h.

Polyethyleneimine grafted with pluronic P85 enhances Ku86 antisense delivery and the ionizing radiation treatment efficacy in vivo

In an effort to improve the efficacy of antisense delivery, we evaluated polyethyleneimine (PEI, 2 kDa) alone or grafted with nonionic amphiphilic block copolymer Pluronic (P85) as a carrier for Ku86 antisense oligonucleotide (ASO) delivery. Ku86 is an abundant nuclear protein that plays an important role in nonhomologous DNA end joining and has implications in tumorigenesis and acquired drug resistance. Transfection of adherent and suspension cell lines with Ku86 ASOs complexed with P85-g-PEI (2 kDa) conjugates was associated with a specific decrease in Ku86 mRNA levels (EC50<75 nM and EC50<250 nM, respectively, n=3). More importantly, no requirement for reduced serum conditions was necessary during transfection. In contrast, whereas Ku86 ASOs complexed with PEI (2 kDa) alone were effective in decreasing Ku86 mRNA levels in adherent cell lines (EC50<75 nM, n=3), the formulation did not produce any detectable decrease in Ku86 mRNA levels in suspension cell lines. Transfection of adherent cell lines with 500 nM Ku86 ASOs formulated with P85-g-PEI (2 kDa) was associated with a specific decrease (<10% remaining of control) in Ku86 protein expression and a two-fold increased cell death after treatment with ionizing radiation (IR). In athymic nude mice bearing subcutaneous human HT29 colon adenocarcinoma xenografts, Ku86 ASO-P85-g-PEI (2 kDa) administration (15 mg/kg, subcutaneously) with a Q1D x 7 treatment schedule, when combined with a single dose of IR (6 Gy), caused a significant inhibition of HT29 tumor growth compared with mismatch- and naked antisense-pretreated control groups (time from 200 to 1000 mm3, 126.9 versus 84.18 and 87.76 days, P<0.005). A potentiation of the antitumor activity was observed in all mice treated with Ku86 ASO-P85-g-PEI (2 kDa) formulation; however, tumor growth inhibition was reversible upon treatment cessation. No morbidity/mortality or changes in histopathology were observed under this treatment regiment. Our results indicate that P85-g-PEI (2 kDa) conjugates may increase the efficacy of Ku86 ASO delivery in management of resistant malignancies, thus providing a rationale for their evaluation in cancer patients in combination with conventional anticancer therapies.

Pharmacokinetics, safety, and efficacy of a liposome encapsulated thymidylate synthase inhibitor, OSI-7904L [(S)-2-[5-[(1,2-dihydro-3-methyl-1-oxobenzo[f]quinazolin-9-yl)methyl]amino-1-oxo-2-isoindolynl]-glutaric acid] in mice.

OSI-7904L [(S)-2-[5-[(1,2-dihydro-3-methyl-1-oxobenzo[f]quinazolin-9-yl)methyl]amino-1-oxo-2-isoindolynl]-glutaric acid] is a liposomal formulation of the highly specific, noncompetitive, thymidylate synthase inhibitor OSI-7904 (also known as GW1843, 1843U89, and GS7904). The liposome formulation was developed to enhance the therapeutic index and dose schedule convenience of this potent antifolate compound. The studies presented here were conducted to determine the antitumor efficacy, distribution, pharmacokinetics, and safety of OSI-7904L in mice. In a human colon adenocarcinoma xenograft model in mice, OSI-7904L demonstrated superior antitumor efficacy compared with OSI-7904 or 5-fluorouracil. Furthermore, OSI-7904L could be administered less frequently than OSI-7904 although still generating greater tumor growth inhibition. Distribution studies confirmed that OSI-7904L-treated animals had much greater plasma, tissue, and tumor exposure than did OSI-7904-treated animals. Tumor exposures, based on area under the curve, in OSI-7904L-treated mice were increased over 100-fold compared with tumor exposures in OSI-7904-treated mice. Plasma exposures following OSI-7904L administration were greater than dose proportional consistent with saturation of plasma clearance mechanisms. OSI-7904L was much more toxic than OSI-7904 in the mouse with primary toxicities to the intestines, bone marrow, and thymus. Minimal toxicity to the lungs and liver was noted. These data clearly demonstrated that in mice, OSI-7904L has an increased plasma residence time as well as increased tissue and tumor exposure compared with OSI-7904, thus resulting in increased potency and toxicity. Potential benefits of OSI-7904L include improved efficacy and a more convenient schedule of administration.