Antagonistic effects of anti-EMMPRIN antibody when combined with chemotherapy against hypovascular pancreatic cancers.

PURPOSE: To examine the antagonistic effects of anti-extracellular matrix metalloprotease inducer (anti-EMMPRIN) antibody when combined with chemotherapy using a hypovascular pancreatic tumor model. PROCEDURES: Severely compromised immunodeficient mice bearing orthotopic MIA PaCa-2 tumors were used (five to six animals per group). Dynamic contrast-enhanced magnetic resonance imaging was used to examine the relationship between tumor vascularity and size. Therapy was initiated when tumors were hypovascular. Treatments included: (1) gemcitabine alone, (2) anti-EMMPRIN antibody alone, and (3) combination, each for 2 weeks. Additionally, another treatment arm included ß-lapachone, an NAD(P)H/quinone 1 (NQO1) bioactivated agent. (18)F-fluoro-D-glucose-positron emission tomography/computed tomography imaging was used weekly to monitor therapeutic effects. RESULTS: Gemcitabine or anti-EMMPRIN monotherapy significantly delayed tumor growth, but the combination therapy showed an antagonistic effect. Similarly, tumor growth was significantly suppressed by ß-lapachone alone, and additive effects were noted when combined with gemcitabine, but the therapeutic efficacy was reduced when anti-EMMPRIN antibody was added. CONCLUSIONS: Anti-EMMPRIN antibody with chemotherapy in hypovascular tumors results in antagonistic effects.

Retargeting of gene expression using endothelium specific hexon modified adenoviral vector.

Adenovirus serotype 5 (Ad5) vectors are well suited for gene therapy. However, tissue-selective transduction by systemically administered Ad5-based vectors is confounded by viral particle sequestration in the liver. Hexon-modified Ad5 expressing reporter gene under transcriptional control by the immediate/early cytomegalovirus (CMV) or the Roundabout 4 receptor (Robo4) enhancer/promoter was characterized by growth in cell culture, stability in vitro, gene transfer in the presence of human coagulation factor X, and biodistribution in mice. The obtained data demonstrate the utility of the Robo4 promoter in an Ad5 vector context. Substitution of the hypervariable region 7 (HVR7) of the Ad5 hexon with HVR7 from Ad serotype 3 resulted in decreased liver tropism and dramatically altered biodistribution of gene expression. The results of these studies suggest that the combination of liver detargeting using a genetic modification of hexon with an endothelium-specific transcriptional control element produces an additive effect in the improvement of Ad5 biodistribution.

Diffusion weighted imaging evaluated the early therapy effect of tamoxifen in an MNU-induced mammary cancer rat model.

PURPOSE: To assess the optimal time point of diffusion-weighted imaging (DWI) for early prognosis of breast cancer following tamoxifen therapy using a methylnitrosourea (MNU)-induced ER-positive breast-cancer model. METHODS: Two groups of Sprague-Dawley rats (n = 15 for group 1; n = 10 for group 2) were used. All animals (50 days old) were intravenously injected with MNU (50 mg/kg body weight) to induce ER-positive mammary tumors. When tumors were approximately 2 cm in diameter, DWI was performed on days 0, 3, and 7, and intratumoral apparent diffusion coefficient (ADC) values were measured. Therapy started on day 0 with tamoxifen (10 mg/kg diet) and continued for 4 weeks for group 1, but only 1 week for group 2, while tumor volume was measured by caliper twice weekly. All animals of group 2 were euthanized on day 7 after imaging, and Ki-67, TUNEL, ERα, and ERß staining were performed on tumor tissue. RESULTS: DW images of MNU-induced mammary tumors were successfully obtained with minimal motion artifact. For group 1, ADC change for 3 days after therapy initiation (ADC3D) was significantly correlated with tumor-volume change until day 11, but the significant correlation between ADC change for 7 days (ADC7D) and the tumor-volume change was observed until day 18. Similarly, for group 2, either ADC7D or ADC3D was significantly correlated with the tumor-volume change, but the higher significance was observed for ADC7D. Furthermore, ADC7D was significantly correlated with apoptotic (TUNEL stained), proliferative (Ki-67 stained), and ERß-positive cell densities, but ADC3D was not significantly correlated with any of those. CONCLUSIONS: ADC7D might be a more reliable surrogate imaging biomarker than ADC3D to assess effectiveness of tamoxifen therapy for ER-positive breast cancer, which may enable personalized treatment. The significant correlation between ADC7D and ERß-positive cell density suggests that ERß may play an important role as a therapeutic indicator of tamoxifen.

Lung resistance-related protein (LRP) expression in malignant ascitic cells as a prognostic marker for advanced ovarian serous carcinoma.

PURPOSE: Ovarian serous carcinoma is an aggressive cancer that often presents with metastatic disease. Although primary tumor and established metastatic foci in the omentum are generally compared to identify proteins involved in drug resistance, we investigated a potential bridge, the malignant cells from ascites, as facilitator of drug resistance and recurrence. METHODS: We evaluated the expression of drug resistance markers P-glycoprotein (P-gp), canalicular multispecific organic anion transporter (MRP2), and lung resistance-related protein (LRP) in malignant cells from ascites and matched omental metastasis from 25 patients with advanced-stage ovarian serous carcinoma who were chemotherapeutic naïve and undergoing initial cytoreductive surgery. Cell viability in vitro, patient response to chemotherapy, and patient survival were correlated with these biomarkers. RESULTS: Of the 25 patients evaluated for a correlation of LRP to 1-year recurrence, we correctly predicted the 1-year recurrence of 24 patients based solely on the presence of LRP in ascitic tumor cells (p=0.01). P-gp and MRP2 were not expressed in malignant cells of ascites or omental metastases. Malignant cells from ascites had higher expression of LRP and were found to be more resistant to carboplatin treatment than cells from omental metastasis (p=0.00375) by in vitro assay. LRP expression in the malignant cells of ascites correlated with carboplatin resistance (p=0.001) by in vitro assay and recurrence at 1 year (p=0.0125). CONCLUSIONS: LRP expression in malignant cells of ascites is a promising marker to predict response to first-line chemotherapy in patients with advanced ovarian serous carcinoma.

Dual combination therapy targeting DR5 and EMMPRIN in pancreatic adenocarcinoma.

The goal of the study was to assess the efficacy of combined extracellular matrix metalloprotease inducer (EMMPRIN)- and death receptor 5 (DR5)-targeted therapy for pancreatic adenocarcinoma in orthotopic mouse models with multimodal imaging. Cytotoxicity of anti-EMMPRIN antibody and anti-DR5 antibody (TRA-8) in MIA PaCa-2 and PANC-1 cell lines was measured by ATPlite assay in vitro. The distributions of Cy5.5-labeled TRA-8 and Cy3-labeled anti-EMMPRIN antibody in the 2 cell lines were analyzed by fluorescence imaging in vitro. Groups 1 to 12 of severe combined immunodeficient mice bearing orthotopic MIA PaCa-2 (groups 1-8) or PANC-1 (groups 9-12) tumors were used for in vivo studies. Dynamic contrast-enhanced-MRI was applied in group 1 (untreated) or group 2 (anti-EMMPRIN antibody). The tumor uptake of Tc-99m-labeled TRA-8 was measured in group 3 (untreated) and group 4 (anti-EMMPRIN antibody). Positron emission tomography/computed tomography imaging with (18)F-FDG was applied in groups 5 to 12. Groups 5 to 8 (or groups 9 to 12) were untreated or treated with anti-EMMPRIN antibody, TRA-8, and combination, respectively. TRA-8 showed high killing efficacy for both MIA PaCa-2 and PANC-1 cells in vitro, but additional anti-EMMPRIN treatment did not improve the cytotoxicity. Cy5.5-TRA-8 formed cellular caps in both the cell lines, whereas the maximum signal intensity was correlated with TRA-8 cytotoxicity. Anti-EMMPRIN therapy significantly enhanced the tumor delivery of the MR contrast agent, but not Tc-99m-TRA-8. Tumor growth was significantly suppressed by the combination therapy, and the additive effect of the combination was shown in both MIA PaCa-2 and PANC-1 tumor models.

(18)F-FDG PET/CT imaging detects therapy efficacy of anti-EMMPRIN antibody and gemcitabine in orthotopic pancreatic tumor xenografts.

PURPOSE: The objective of this study is to evaluate the therapeutic response to a novel monoclonal antibody targeting human extracellular matrix metalloproteinase inducer (EMMPRIN) in combination with gemcitabine in a pancreatic-tumor xenograft murine model by sequential 2-deoxy-2-[18F]fluoro-D-glucose ((18)F-FDG) positron emission tomography/computed tomgraphy (PET/CT) imaging. PROCEDURES: Four groups of SCID mice bearing orthotopic pancreatic tumor xenografts were injected with phosphate-buffered saline, gemcitabine (120 mg/kg BW), anti-EMMPRIN antibody (0.2 mg), or combination, respectively, twice weekly for 2 weeks, while (18)F-FDG PET/CT imaging was performed weekly for 3 weeks. Changes in mean standardized uptake value (SUV(mean)) of (18)F-FDG and volume of tumors were determined. RESULTS: The tumor SUV(mean) change in the group receiving combination therapy was significantly lower than those of the other groups. Tumor-volume changes of groups treated with anti-EMMPRIN monotherapy or combined therapy were significantly lower than that of the control group. CONCLUSIONS: These data provide support for clinical studies of anti-EMMPRIN therapy with gemcitabine for pancreatic cancer treatment.

Extracelluar matrix metalloproteinase as a novel target for pancreatic cancer therapy.

The objective of this study was to evaluate extracellular matrix metalloproteinase (EMMPRIN) as a novel target in orthotopic pancreatic cancer murine models. MIA PaCa-2 human pancreatic tumor cells were implanted in groups 1 and 3-7, whereas MIA PaCa-2 EMMPRIN knockdown cells were implanted in group 2. Dosing with anti-EMMPRIN antibody started immediately after implantation for groups 1-3 (residual tumor model) and at 21 days after cell implantation for groups 4-7 (established tumor model). Groups 3, 5, and 7 were treated with anti-EMMRPIN antibody (0.2-1.0 mg) twice weekly for 2-3 weeks, whereas the other groups served as the control. In the residual tumor model, tumor growth of anti-EMMPRIN-treated group was successfully arrested for 21 days (15 ± 4 mm(3)), which was significantly lower than that of the EMMPRIN knockdown group (80 ± 15 mm(3); P=0.001) or the control group (240 ± 41 mm(3); P<0.001). In the established tumor model, anti-EMMPRIN therapy lowered tumor volume increase by approximately 40% compared with the control, regardless of the dose amount. Ki67-expressed cell density of group 5 was 939 ± 150 mm(-2), which was significantly lower than that of group 4 (1709 ± 145 mm(-2); P=0.006). Microvessel density of group 5 (30 ± 6 mm(-2)) was also significantly lower than that of group 4 (53 ± 5 mm(-2); P=0.014), whereas the microvessel size of group 5 (191 ± 22 µm(2)) was significantly larger than that of group 4 (113 ± 26 µm(2); P=0.049). These data show the high potential of anti-EMMPRIN therapy for pancreatic cancer and support its clinical translation.

Expression and histopathological correlation of CCR9 and CCL25 in ovarian cancer.

Ovarian carcinoma is the most lethal gynecological malignancy among women and its poor prognosis is mainly due to metastasis. Chemokine receptor CCR9 is primarily expressed by a small subset of immune cells. The interactions between CCL25 and CCR9 have been implicated in leukocyte trafficking to the small bowel, a frequent metastatic site for ovarian cancer cells. We have previously shown that ovarian cancer cells express CCR9 and play an important role in cell migration, invasion and survival in the presence of its natural ligand in vitro. In this study, we have evaluated the expression of CCR9 and CCL25 in ovarian cancer cells and clinical samples. Ovarian cancer tissue microarrays from University of Alabama at Birmingham and AccuMax were stained for CCR9 and CCL25. Aperio ScanScope was used to acquire 80X digital images and expression analysis of CCR9 and CCL25. Flow cytometry and the Image stream system were used to conform the expression of CCR9 and CCL25 in ovarian cancer cells. Our results show significantly higher (p<0.001) expression of CCR9 and CCL25 in serous adenocarcinoma followed by serous papillary cystadenoma, endometrioid adenocarcinoma, mucinous adenocarcinoma, cystadenoma, mucinous boderline adenocarcinoma, clear cell carcinoma, granulosa cell tumor, dysgerminoma, transitional cell carcinoma, Brenner tumor, yolk sac tumor, adenocarcinoma and fibroma cases, compared to non-neoplastic ovarian tissue. Similar to tissue expression, CCR9 was also significantly expressed by the ovarian cancer cell lines (OVCAR-3 and SK-OV-3) in comparison to normal adult ovarian epithelial cell. We provide the first evidence that CCR9 and its natural ligand CCL25 are highly expressed by ovarian cancer tissue and their expression correlates with histological subtypes. Expression of this chemokine receptor and its ligand CCL25 within primary tumor tissue further suggests a potential role of this chemokine-receptor axis in ovarian cancer progression.

Early therapy evaluation of combined cetuximab and irinotecan in orthotopic pancreatic tumor xenografts by dynamic contrast-enhanced magnetic resonance imaging.

Early pancreatic cancer response following cetuximab and/or irinotecan therapies was measured by serial dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) before and during therapy. Groups 1 to 4 (n  =  6/group) of SCID mice bearing orthotopic pancreatic adenocarcinoma xenografts expressing luciferase were treated with phosphate-buffered saline, cetuximab, irinotecan, or cetuximab combined with irinotecan, respectively, twice weekly for 3 weeks. DCE-MRI was performed on days 0, 1, 2, and 3 after therapy initiation, whereas anatomic magnetic resonance imaging was performed on days 0, 1, 2, 3, 6, and 13. Bioluminescence imaging was performed on days 0 and 21. At day 21, all tumors were collected for further histologic analyses (Ki-67 and CD31 staining), whereas tumor dimensions were measured by calipers. The Ktrans values in the 0.5 mm-thick peripheral tumor region were calculated, and the changes in Ktrans during the 3 days posttherapy were compared to tumor volume changes, bioluminescent signal changes, and histologic findings. The Ktrans changes in the peripheral tumor region after 3 days of therapy were linearly correlated with 21-day decreases in tumor volume (p < .001), bioluminescent signal (p  =  .050), microvessel densities (p  =  .002), and proliferating cell densities (p  =  .001). This study supports the clinical use of DCE-MRI for pancreatic cancer patients for early assessment of an anti-epidermal growth factor receptor therapy combined with chemotherapy.

Inhibition of the catalytic function of activation-induced cytidine deaminase promotes apoptosis of germinal center B cells in BXD2 mice.

OBJECTIVE: To determine whether functional suppression of the catalytic domain of activation-induced cytidine deaminase (AID) can suppress the hyperreactive germinal center (GC) responses in BXD2 mice. METHODS: We generated transgenic BXD2 mice expressing a dominant-negative (DN) form of Aicda at the somatic hypermutation site (BXD2-Aicda-DN-transgenic mice). Real-time quantitative reverse transcriptase-polymerase chain reaction was used to determine the expression of Aicda and DNA damage/repair genes. Enzyme-linked immunosorbent assay was used to measure serum levels of autoantibodies and immune complexes (ICs). Development of GCs and antibody-containing ICs as well as numbers of proliferative and apoptotic cells were determined using flow cytometry and/or immunohistochemical analyses. Development of arthritis and kidney disease was evaluated histologically in 6-8-month-old mice. RESULTS: Suppression of the somatic hypermutation function of AID resulted in a significant decrease in autoantibody production without affecting the expression of DNA damage-related genes in GC B cells of BXD2-Aicda-DN-transgenic mice. There was decreased proliferation, increased apoptosis, increased expression of caspase 9 messenger RNA in GC B cells, and lower numbers of GCs in the spleens of BXD2-Aicda-DN-transgenic mice. Decreased GC response was associated with lower levels of IgG-containing ICs. Anti-IgM- and anti-CD40 plus anti-Ig-induced B cell proliferative responses were decreased in BXD2-Aicda-DN-transgenic mice. CONCLUSION: Inhibition of the AID somatic hypermutation function in BXD2 mice suppressed development of spontaneous GCs, generation of autoantibody-producing B cells, and autoimmunity in BXD2 mice. Suppression of AID catalytic function to limit selection-based survival of GC B cells could become a novel therapy for the treatment of autoimmune disease.

CCL25 mediates migration, invasion and matrix metalloproteinase expression by breast cancer cells in a CCR9-dependent fashion.

Breast cancer (BrCa) is one of the most frequently diagnosed cancers and the second leading cause of cancer-related deaths in North American women. Most deaths are caused by metastasis, and BrCa is characterized by a distinct metastatic pattern involving lymph nodes, bone marrow, lung, liver and brain. Migration of metastatic cells share many similarities with leukocyte trafficking, which are regulated by chemokines and their receptors. The current study evaluates the expression and functional role of CCR9, and its only known ligand, CCL25, in BrCa cell migration and invasion. Quantitative immunohistochemical analysis showed that both moderately and poorly differentiated BrCa tissue expressed significantly more (P<0.0001) CCR9 compared to non-neoplastic breast tissue. Interestingly, poorly differentiated BrCa tissue expressed significantly more (P<0.0001) CCR9 compared to moderately differentiated BrCa tissue. Similarly, CCR9 was highly expressed by the aggressive breast cancer cell line (MDA-MD-231) compared to the less aggressive MCF-7. Migration as well as invasion assays were used to evaluate the functional interaction between CCR9 and CCL25 in BrCa cell lines (MDA-MB-231 and MCF-7). Neutralizing CCR9-CCL25 interactions significantly impaired the migration and invasion of BrCa cells. Furthermore, CCL25 enhanced the expression of MMP-1, -9, -11 and -13 active proteins by BrCa cells in a CCR9-dependent fashion. These studies show CCR9 is functionally and significantly expressed by BrCa (poorly > moderately differentiated) tissue and cells as well as that CCL25 activation of this receptor promotes breast tumor cell migration, invasion and MMP expression, which are key components of BrCa metastasis.

DCE-MRI detects early vascular response in breast tumor xenografts following anti-DR5 therapy.

PURPOSE: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) measured the early vascular changes after administration of TRA-8, bevacizumab, or TRA-8 combined with bevacizumab in breast tumor xenografts. PROCEDURES: Groups 1-4 of nude mice bearing human breast carcinoma were injected with phosphate-buffered saline, TRA-8, bevacizumab, and TRA-8 + bevacizumab on day 0, respectively. DCE-MRI was performed on days 0, 1, 2, and 3, and thereafter tumors were collected for terminal deoxynucleotidyl transferase-mediated dUT nick end labeling and CD31 staining. RESULTS: DCE-MRI measured a significant K (trans) change within 3 days after TRA-8 therapy that correlated with tumor growth arrest, which was not shown with statistical significance by histopathology at these early time points posttreatment. The K (trans) changes followed quadratic polynomial curves. CONCLUSION: DCE-MRI detected significantly lower K (trans) levels in breast tumor xenografts following TRA-8 monotherapy or combined therapy with bevacizumab.

A phase I study of a tropism-modified conditionally replicative adenovirus for recurrent malignant gynecologic diseases.

PURPOSE: To determine the maximum tolerated dose (MTD), toxicity spectrum, clinical activity, and biological effects of the tropism-modified, infectivity-enhanced conditionally replicative adenovirus (CRAd), Ad5-Δ24-Arg-Gly-Asp (RGD), in patients with malignant gynecologic diseases. EXPERIMENTAL DESIGN: Cohorts of eligible patients were treated daily for 3 days through an i.p. catheter. Vector doses ranged from 1 × 10(9) to 1 × 10(12) viral particles per day. Toxicity was evaluated using CTCv3.0. CA-125 and Response Evaluation Criteria in Solid Tumors (RECIST) criteria were used to determine clinical efficacy. Corollary biological studies included assessment of CRAd replication, wild-type virus generation, viral shedding, and neutralizing antibody response. RESULTS: Twenty-one patients were treated. Adverse clinical effects were limited to grade 1/2 fever, fatigue, or abdominal pain. No vector-related grade 3/4 toxicities were noted. No clinically significant laboratory abnormalities were noted. The maximum tolerated dose was not reached. Over a 1 month follow-up, 15 (71%) patients had stable disease and six (29%) had progressive disease. No partial or complete responses were noted. Seven patients had a decrease in CA-125; four had a >20% drop. RGD-specific PCR showed the presence of study vector in ascites of 16 patients. Seven revealed an increase in virus after day 3, suggesting replication of Ad5-Δ24-RGD. Minimal wild-type virus generation was detected. Viral shedding studies showed insignificant shedding in the serum, saliva, and urine. Anti-adenoviral neutralizing antibody effects were prevalent. CONCLUSIONS: This study, the first to evaluate an infectivity-enhanced CRAd in human cancer, shows the feasibility, safety, potential antitumor response, and biological activity of this approach in ovarian cancer. Further evaluation of infectivity enhanced virotherapy approaches for malignant gynecologic diseases is warranted.

KISS1 over-expression suppresses metastasis of pancreatic adenocarcinoma in a xenograft mouse model.

Identifying molecular targets for treatment of pancreatic cancer metastasis is critical due to the high frequency of dissemination prior to diagnosis of this lethal disease. Because the KISS1 metastasis suppressor is expressed at reduced levels in advanced pancreatic cancer, we hypothesized that re-expression of KISS1 would reduce metastases. Highly metastatic S2VP10 cells expressing luciferase (S2VP10L) were transfected with a FLAG-tagged version of KISS1 (KFM), KFMΔSS (with deleted secretion signal sequence), or pcDNA3 control plasmid (CP) and expression was confirmed by RTQ-PCR. SCID mice were implanted orthotopically with S2VP10L cells or transfectants and tumor growth and metastases were monitored using bioluminescence imaging. Mice with S2VP10L-KISS1 tumors developed fewer liver (98%) and lung (99%) metastases than S2VP10L. Unexpectedly, mice with S2VP10L-KFMΔSS tumors also had reduced liver and lung metastases, but had more metastases than mice with S2VP10L-KISS. KISS1 protein was found in the cytoplasm of both KFMΔSS and KISS1-expressing orthotopic tumors by immunohistochemistry. Metastases were not found in lungs of mice with S2VP10L-KISS1 tumors; whereas, KFMΔSS lung sections had regions of concentrated KISS1 staining, suggesting that secretion of KISS1 is needed to reduce metastasis significantly. These data suggest induction of KISS1 expression has potential as an adjuvant treatment for pancreatic cancer.

Experimental cancer therapy using restoration of NAD+ -linked 15-hydroxyprostaglandin dehydrogenase expression.

Preclinical and clinical evidence shows that cyclooxygenase-2 (Cox-2)-mediated prostaglandin E(2) (PGE(2)) overexpression plays an important role in tumor growth, metastasis, and immunosuppression. It has been shown that expression of NAD(+)-linked 15-hydroxyprostaglandin dehydrogenase (15-PGDH), a key enzyme responsible for PGE(2) inactivation, is suppressed in the majority of cancers, including breast and colon carcinoma. We have developed adenoviral vectors (Ad) encoding the 15-PGDH gene under control of the vascular endothelial growth factor receptor 1 (VEGFR1/flt-1; Adflt-PGDH) and the Cox-2 (Adcox-PGDH) promoters. The purpose of this study was to investigate cytotoxicity in vitro and therapeutic efficacy in vivo of 15-PGDH-mediated cancer therapy. The levels of PGE(2) and VEGF expression were correlated with PGE(2) receptor and Cox-2 and flt-1 expression in cancer cells. The in vitro study showed that Ad-mediated 15-PGDH expression significantly decreased proliferation and migration of cancer cells. Animal breast and colon tumor therapy studies showed that 15-PGDH gene therapy produced a significant delay in 2LMP and LS174T tumor growth. Combined therapy using 15-PGDH and anti-VEGF antibody (bevacizumab) significantly increased inhibition of growth of LS174T tumor xenografts in comparison with agents alone. These results suggest that 15-PGDH-mediated regulation of PGE(2) catabolism in the tumor microenvironment represents a novel approach for therapy of human breast and colon cancer.

Effect of TRA-8 anti-death receptor 5 antibody in combination with chemotherapy in an ex vivo human ovarian cancer model.

OBJECTIVES: To investigate the cytotoxicity of TRA-8, an antibody that specifically binds death receptor 5, alone and in combination with chemotherapy, using an ex vivo human ovarian cancer model. MATERIALS AND METHODS: Twenty-six ovarian cancer specimens were obtained during ovarian cancer debulking, and tumor slices were prepared with the Krumdieck tissue slicer. The tumor slices were exposed to varying concentrations of TRA-8, carboplatin/paclitaxel, or the combination of TRA-8 and chemotherapy. Using nonlinear modeling, dose-response curves and IC50 values were generated for specimens treated with TRA-8. The additive and synergistic cytotoxic effects of chemotherapy combination with TRA-8 were evaluated in specimens. In addition to adenosine triphosphate viability assays, the treated and untreated slices were assessed by immunohistochemistry to confirm apoptosis induction. RESULTS: Specimens from 13 patients yielded TRA-8-induced IC50 values. Of these specimens, 15% were found to be sensitive to TRA-8-induced cytotoxicity at IC50 doses less than 500 ng/mL. Specimens from 13 patients underwent combination treatment with TRA-8 and carboplatin/paclitaxel. Of these specimens, 77% exhibited additive cytotoxicity in comparison with those treated with either agent alone, whereas 15% exhibited synergistic cytotoxicity. Immunohistochemical analysis of terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling and cleaved caspase 3 staining demonstrated a dose-dependent increase in apoptosis with the combination treatment. CONCLUSIONS: This study demonstrates the efficacy of the death receptor monoclonal antibody TRA-8 in combination with conventional chemotherapy in an ex vivo human ovarian cancer model. This model can be used to assess cytotoxicity of novel agents in combination with chemotherapy in ovarian cancer.

Regulation of p53 by TopBP1: a potential mechanism for p53 inactivation in cancer.

Proper control of the G(1)/S checkpoint is essential for normal proliferation. The activity of p53 must be kept at a very low level under unstressed conditions to allow growth. Here we provide evidence supporting a crucial role for TopBP1 in actively repressing p53. Depletion of TopBP1 upregulates p53 target genes involved in cell cycle arrest and apoptosis and enhances DNA damage-induced apoptosis. The regulation is mediated by an interaction between the seventh and eighth BRCT domains of TopBP1 and the DNA-binding domain of p53, leading to inhibition of p53 promoter binding activity. Importantly, TopBP1 overexpression is found in 46 of 79 primary breast cancer tissues and is associated with high tumor grade and shorter patient survival time. Overexpression of TopBP1 to a level comparable to that seen in breast tumors leads to inhibition of p53 target gene expression and DNA damage-induced apoptosis and G(1) arrest. Thus, a physiological level of TopBP1 is essential for normal G(1)/S transition, but a pathological level of TopBP1 in cancer may perturb p53 function and contribute to an aggressive tumor behavior.

Pulmonary angiogenesis in a rat model of hepatopulmonary syndrome.

BACKGROUND & AIMS: Hepatopulmonary syndrome (HPS), defined as intrapulmonary vasodilation, occurs in 10%-30% of cirrhotics and increases mortality. In a rat model of HPS induced by common bile duct ligation (CBDL), but not thioacetamide (TAA)-induced nonbiliary cirrhosis, lung capillary density increases, monocytes accumulate in the microvasculature, and signaling factors in the angiogenesis pathway (Akt and endothelial nitric oxide synthase [eNOS]) are activated. Pentoxifylline (PTX) directly decreases lung endothelial Akt and eNOS activation, blocks intravascular monocyte accumulation, and improves experimental HPS; we evaluated whether pulmonary angiogenesis develops in this model. METHODS: TAA- and PTX-treated animals were evaluated following CBDL. Lung angiogenesis was assessed by quantifying factor VIII-positive microvessels and levels of von Willebrand factor (vWf), vascular endothelial cadherin (VE-cadherin), and proliferating cell nuclear antigen (PCNA). Angiogenic factors including phospho-Akt, phospho-eNOS, vascular endothelial growth factor (VEGF)-A, and phospho-VEGF receptor-2 (p-VEGFR-2) were compared and monocyte accumulation was assessed. RESULTS: Following CBDL, but not TAA exposure, rats developed HPS that was temporally correlated with increased numbers of lung microvessel; increased levels of vWf, VE-cadherin and PCNA; and activation of Akt and eNOS. Angiogenesis was accompanied by increased pulmonary VEGF-A and p-VEGFR-2 levels, with VEGF-A staining in accumulated intravascular monocytes and alveolar endothelial cells. Following CBDL, PTX-treated rats had reduced numbers of microvessels, reduced lung monocyte accumulation, downregulation of pulmonary angiogenic factors, and reduced symptoms of HPS. CONCLUSIONS: A specific increase in pulmonary angiogenesis occurs as experimental HPS develops, accompanied by activation of VEGF-A-associated angiogenic pathways. PTX decreases the angiogenesis, reduces the symptoms of HPS, and downregulates VEGF-A mediated pathways.

Early therapy evaluation of combined anti-death receptor 5 antibody and gemcitabine in orthotopic pancreatic tumor xenografts by diffusion-weighted magnetic resonance imaging.

Early therapeutic efficacy of anti-death receptor 5 antibody (TRA-8) combined with gemcitabine was measured using diffusion-weighted magnetic resonance imaging (DWI) in an orthotopic pancreatic tumor model. Groups 1 to 4 of severe combined immunodeficient mice (n = 5-7 per group) bearing orthotopically implanted, luciferase-positive human pancreatic tumors (MIA PaCa-2) were subsequently (4-5 weeks thereafter) injected with saline (control), gemcitabine (120 mg/kg), TRA-8 (200 mug), or TRA-8 combined with gemcitabine, respectively, on day 0. DWI, anatomic magnetic resonance imaging, and bioluminescence imaging were done on days 0, 1, 2, and 3 after treatment. Three tumors from each group were collected randomly on day 3 after imaging, and terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling staining was done to quantify apoptotic cellularity. At just 1 day after starting therapy, the changes of apparent diffusion coefficient (ADC) in tumor regions for group 3 (TRA-8) and group 4 (TRA-8/Gem) were 21 +/- 9% (mean +/- SE) and 27 +/- 3%, respectively, significantly higher (P < 0.05) than those of group 1 (-1 +/- 5%) and group 2 (-2 +/- 4%). There was no statistical difference in tumor volumes for the groups at this time. The mean ADC values of groups 2 to 4 gradually increased over 3 days, which were concurrent with tumor volume regressions and bioluminescence signal decreases. Apoptotic cell densities of tumors in groups 1 to 4 were 0.7 +/- 0.4%, 0.6 +/- 0.2%, 3.1 +/- 0.9%, and 4.7 +/- 1.0%, respectively, linearly proportional to the ADC changes on day 1. Further, the ADC changes were highly correlated with the previously reported mean survival times of animals treated with the same agents and doses. This study supports the clinical use of DWI for pancreatic tumor patients for early assessment of drug efficacy.

Breast tumor xenografts: diffusion-weighted MR imaging to assess early therapy with novel apoptosis-inducing anti-DR5 antibody.

PURPOSE: To measure the early therapeutic response to a novel apoptosis-inducing antibody, TRA-8, by using diffusion-weighted magnetic resonance (MR) imaging in a mouse breast cancer model. MATERIALS AND METHODS: Animal experiments had institutional animal care and use committee approval. Four groups of nude mice bearing luciferase-positive breast tumors (four to five mice with eight to 10 tumors per group) were injected intravenously with 0 mg (group 1), 0.025 mg (group 2), 0.100 mg (group 3), or 0.200 mg (group 4) of TRA-8 on days 0 and 3. Diffusion-weighted imaging, anatomic MR imaging, and bioluminescence imaging were performed on days 0, 3, and 6 before dosing. Averaged apparent diffusion coefficients (ADCs) for both whole tumor volume and a 1-mm peripheral tumor shell were calculated and were compared with tumor volume and living tumor cell changes. After imaging at day 6, proliferating and apoptotic cell densities were measured with Ki67 and terminal deoxynucleotidyl transferase mediated dUTP nick end labeling, or TUNEL, staining, respectively, and were compared with cleaved caspase-3 density. RESULTS: The ADC increase at day 3 was dependent on TRA-8 dose level, averaging 6% +/- 3 (standard error of mean), 19% +/- 4, 14% +/- 4, and 34% +/- 7 in the whole tumor volume and 1% +/- 2, 9% +/- 5, 13% +/- 5, and 30% +/- 8 in the outer 1-mm tumor shell only for groups 1, 2, 3, and 4, respectively. The ADC increase in group 4 was significantly higher (P = .0008 and P = .0189 for whole tumor volume and peripheral region, respectively) than that in group 1 on day 3, whereas tumor size did not significantly differ. At day 3, the dose-dependent ADC increases were linearly proportional to apoptotic cell and cleaved caspase-3 densities and were inversely proportional to the density of cells showing Ki67 expression. CONCLUSION: Diffusion-weighted imaging enabled measurement of early breast tumor response to TRA-8 treatment, prior to detectable tumor shrinkage, providing an effective mechanism to noninvasively monitor TRA-8 efficacy. SUPPLEMENTAL MATERIAL: http://radiology.rsnajnls.org/cgi/content/full/248/3/844/DC1.