Improved nonviral cancer suicide gene therapy using survivin promoter-driven mutant Bax

Suicide gene vectors are being developed in many laboratories as an attractive approach to cancer therapy. However, the development of these therapies is hampered by safety concerns and limitations of efficacy. The use of tumor-specific promoters, such as survivin promoter, can provide much needed specificity to target tumor cells. However, the expression levels from these promoters is often suboptimal and hence it is imperative to enhance the activity of the cytotoxic gene of interest. We tested apoptotic activity of several mutants of proapoptotic gene bax that constitutively translocate to the mitochondria and induce apoptosis. One of these mutants with deletion of serine at position S184 (S184del) was found to be most active and showed significant antitumor activity when expressed by the survivin promoter. In vitro testing shows that this vector (Sur-BaxS184del) induces cell killing in a variety of tumor cell lines of different origin with significantly higher efficacy than wild-type bax (Sur-BaxWT). The increase in cytotoxicity was a result of enhanced induction of apoptosis in tumor cells. In contrast to cytomegalovirus (CMV) promoter-driven bax (CMV-Bax), Sur-BaxS184del caused minimum toxicity in normal human dermal fibroblasts validating its specificity and safety. In a mouse tumor model (DA-3, murine breast cancer cells), we show that intratumoral injection of Sur-BaxS184del resulted in tumor growth retardation to the same level as CMV-Bax. This study highlights the effectiveness of using bax mutants in combination with survivin promoter for tumor-targeted suicide gene therapy in a nonviral vector.

Molecular targeting of HER2 for diagnosis and therapy of breast cancer

Abstract #6004

Background: Expression of HER2 receptors in breast cancer is correlated with poor prognosis and may be different in distant metastases as compared to the primary tumor. We are developing methods to assess global expression of HER2 in vivo and to deliver therapeutic agents specifically to HER2-positve cells.
 Materials and Methods: As the targeting agent we use an Affibody molecule (http://www.affibody.com). These very stable and highly soluble proteins are relatively small (8.3 kDa) and bind to HER2 receptors with high affinity (22 pM). For imaging with PET, SPECT, or optical methods, an appropriate group containing the imaging beacon can be attached by a selective chemical reaction to a unique C-terminal cysteine residue of Affibody. For therapeutic purposes, they can be conjugated to multifunctional nanoparticles containing both imaging and therapeutic agents. We have conjugated affibody molecules with thermo-sensitive liposomes or gold nanoparticles (subsequently activated with neutrons) and characterized their biodistribution using optical imaging and SPECT, respectively. We used PET imaging with 18F-ZHER2-Affibody to monitor the down-regulation of HER2 following four doses (50 mg/kg) of 17-dimethylaminoethylamino-17-demethoxy-geldanamycin, 17-DMAG, an inhibitor of Hsp90 known to decrease HER2 expression. Animals were scanned before and after treatment. Immediately after the last scan, the mice were euthanized and tumors were frozen for ex-vivo analysis of receptor expression. For optical imaging, we used AlexaFluor dyes conjugated with affibody molecules containing an albumin binding domain that extended their circulation time. We have attached nanoparticles (liposomes and gold) to Affibody molecules using the same type of maleimide chemistry.
 Results: Our results showed that Affibody molecules do not affect the targeted cells and that their binding does not interfere with either the binding or the effectiveness of trastuzumab. 18F-ZHER2-Affibody was eliminated quickly from blood and normal tissues, providing high tumor/blood and tumor/muscle ratios by 1h post injection. The signal obtained from PET and optical imaging correlated well with the number of receptors expressed in the studied tumors as assessed by western blot, ELISA, and IHC. Following 17-DMAG treatment, the level of HER2 expression, estimated by PET imaging, in BT474 and Mcf-7/clone18 tumors decreased 70% and 30%. This change was confirmed by the biodistribution studies, ELISA and western blot.
 Discussion: This strategy, involving assessment of target presence and distribution in an individual patient followed by optimized, target-specific drug delivery, may significantly improve efficacy of breast cancer treatment while reducing side effects.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6004.

The coupling of an enzymatic reaction to transmembrane flow of electric current in a synthetic "active transport" system

If a chemical reaction is constrained to occur within an asymmetric structure, e.g. by the presence of bound or otherwise trapped enzyme, coupling of the reaction to the flow of one or more solutes, or to the flow of electric current, becomes possible. Such systems can serve as models in which transport is "driven" by chemical reaction. In this respect the processes involved are analogous to active transport, though the molecular mechanisms may be quite different from those in nature. A simple arrangement of this kind has been studied: a composite membrane consisting of two ion exchange membranes of opposite fixed charge, separated by an intermediate layer of solution containing papain. An uncharged substrate of low molecular weight acts as "fuel" for the system, N-acetyl-L-glutamic acid diamide. This material (not previously described) hydrolyzes in the presence of papain to ammonium N-acetyl-L-glutamine. The composite membrane gives rise to an electromotive force, ultimately reaching a stationary state, when clamped between two identical solutions in which the affinity of the reaction has been fixed. Onsager's reciprocity relation has not hitherto been tested in a case of coupling between chemical reaction and a vectorial flow (here electric current); its validity for this system, in which stationary-state coupling occurs, was established over the experimental range of affinities (up to 3 kcal/mole).

Role of HIV Gp41 mediated fusion/hemifusion in bystander apoptosis

Mechanisms of HIV-mediated CD4+ T cell loss leading to immunodeficiency are amongst the most extensively studied yet unanswered questions in HIV biology. The level of CD4+ T cell depletion in HIV infected patients far exceeds the number of infected T cells, suggesting an indirect mechanism of HIV pathogenesis termed bystander cell death. Evidence is accumulating that the HIV envelope glycoprotein (Env) is a major determinant of HIV pathogenesis and plays a critical role in bystander cell death. The complex structure and function of HIV Env makes the determination of the mechanism of Env mediated apoptosis more complex than previously thought. This review will examine the complex relationship between HIV Env phenotype, coreceptor expression and immune activation in determining HIV pathogenesis. We review data here corresponding to the role of HIV Env hemifusion activity in HIV pathogenesis and how it interplays with other AIDS associated factors such as chemokine receptor expression and immune activation.

Use of the ABC care bundle to standardize guideline implementation in a cardiac surgical population: a pilot study

A cardiac surgical progressive care unit implemented the ABC's of Cardiovascular Risk Reduction Care Bundle to determine whether the use of a packaged approach to medication prescription and lifestyle counseling would improve adherence to secondary risk-reduction guidelines in postcoronary artery bypass graft patients. A pilot study was carried out to assess changes in adherence to guideline recommendations post-Care Bundle implementation. Findings support using a systematic strategy to improve guideline adherence in this population.

Dissecting HIV fusion: identifying novel targets for entry inhibitors

Significant momentum has been recently generated in understanding the HIV fusion process. This has led to the development of a host of HIV entry inhibitors which are currently in preclinical and/or clinical development or have been approved for clinical use. In this review we update our understanding of HIV fusion, specifically highlighting novel mechanisms and agents that inhibit this process. Major focus will be placed on three key areas. Initially viral attachment will be reviewed as recent developments in this field emphasize the importance of understanding cell type specific interactions with HIV. This has aided in identifying promising targets for the development of attachment inhibitors. Secondly, we will review the role of cellular lipids in HIV entry. Glycosphingolipids have been shown to interact with different components of the HIV fusion machinery and agents that perturb glycosphingolipid biosynthesis have inhibitory effects on HIV fusion. Likewise, manipulating ceramide biosynthesis also inhibits HIV fusion. Here, we describe how manipulating cellular lipids inhibits HIV fusion and how lipid biosynthesis can be modulated to potentially prevent HIV infection. We end this review by discussing the notion of targeting select host cell proteins for HIV therapy. We will review the role of the cellular proteins PDI, defensins and cytoskeletal proteins in facilitating the fusion reaction. As our understanding of the HIV fusion process increases, the identification of targets for developing entry inhibitors becomes more diverse. Given the rapid resistance of HIV to any selective pressure this is an important avenue in the advancement of drug therapy.

Anti-CD74-doxorubicin immunoconjugate (IMMU-110) is cytotoxic in non-Hodgkin’s lymphoma (NHL) models and overcomes MDR

7598

Background: The internalizing LL1 anti-CD74 antibody is an optimal agent for delivering drugs, toxins, or radionuclides to CD74+ cancer cells. Here, we investigated the efficacy of IMMU-110 (Immunomedics, Inc.) in common follicular and aggressive types of NHL cells and in two disseminated non-Burkitt NHL models. Methods: CD74, MDR and MRP expression on NHL cell lines was determined by flow cytometry. In vitro cytotoxicity was assessed by cell cycle analysis of propidium iodide (PI)-stained cells and by measuring apoptotic cells using FITC-Annexin V and PI. In vivo therapy of a single 350-μg dose of IMMU-110 was evaluated in disseminated SUDHL4 and FSCCL. Results: Raji and Daudi Burkitt lines express similar amounts of CD74 (>93% positive cells and a MCF=35), yet a 3-day treatment with 0.8 μg/ml of IMMU-110 results is 18.4% of Raji and 67.9% of Daudi cells in Sub-Go. Aside from Daudi cells that respond with cells shifting into Sub-Go, most other NHL cell lines experience a G2/M block (44%-82% of cells) in response to a 3-day exposure to IMMU-110. Both MDR- and MDR+ NHL cells responded to IMMU-110. Kaplan Meier analysis showed a significant increase in survival of both SUDHL4 (MDR-/MRP-)- and FSCCL (MDR+/MRP+)-bearing SCID mice (P < 0.025) with 100% survival of treated mice vs. 38% survival of untreated mice at 70–77 days post cell implantation. Conclusions: IMMU-110 is cytotoxic in non-Burkitt and in Burkitt NHL cell lines. The magnitude of the cytotoxic response is not related to the amount of CD74 expressed on the cell surface. IMMU-110 is therapeutic in drug-sensitive (SUDHL4) and drug-resistant (FSCCL) NHL models, suggesting that antibody targeting can bypass the MDR drug efflux system that prevents free doxorubicin from being therapeutic.

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The clinical potential of sphingolipid-based therapeutics

The era of sphingolipid-based therapeutics is upon us. A large body of work has been accumulating that demonstrates the distinct biological roles of sphingolipids in maintaining a homeostatic environment and in responding to environmental stimuli to regulate cellular processes. It is thus necessary to further investigate alterations in sphingolipid-metabolism in pathological conditions and, in turn, try to exploit altered sphingolipid-metabolizing enzymes and their metabolites as therapeutic targets. This review will examine how advances in the fields of drug delivery, drug discovery, synthetic chemistry, enzyme replacement therapy, immunobiology, infectious disease and nanotechnology have delivered the potential and promise of utilizing and/or targeting sphingolipid metabolites as therapies for diverse diseases.

Genome-wide linkage scan in a large bipolar disorder sample from the National Institute of Mental Health genetics initiative suggests putative loci for bipolar disorder, psychosis, suicide, and panic disorder

We conducted a 9-cM genome scan in a large bipolar pedigree sample from the National Institute of Mental Health genetics initiative (1060 individuals from 154 multiplex families). We performed parametric and nonparametric analyses using both standard diagnostic models and comorbid conditions thought to identify phenotypic subtypes: psychosis, suicidal behavior, and panic disorder. Our strongest linkage signals (genome-wide significance) were observed on chromosomes 10q25, 10p12, 16q24, 16p13, and 16p12 using standard diagnostic models, and on 6q25 (suicidal behavior), 7q21 (panic disorder) and 16p12 (psychosis) using phenotypic subtypes. Several other regions were suggestive of linkage, including 1p13 (psychosis), 1p21 (psychosis), 1q44, 2q24 (suicidal behavior), 2p25 (psychosis), 4p16 (psychosis, suicidal behavior), 5p15, 6p25 (psychosis), 8p22 (psychosis), 8q24, 10q21, 10q25 (suicidal behavior), 10p11 (psychosis), 13q32 and 19p13 (psychosis). Over half the implicated regions were identified using phenotypic subtypes. Several regions - 1p, 1q, 6q, 8p, 13q and 16p - have been previously reported to be linked to bipolar disorder. Our results suggest that dissection of the disease phenotype can enrich the harvest of linkage signals and expedite the search for susceptibility genes. This is the first large-scale linkage scan of bipolar disorder to analyze simultaneously bipolar disorder, psychosis, suicidal behavior, and panic disorder.

The relationship between blood pressure and C-reactive protein in the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVES

The goal of this study was to determine the relationship between resting blood pressure (BP) and C-reactive protein (CRP) in a multi-ethnic cohort of men and women from the Multi-Ethnic Study of Atherosclerosis (MESA).

BACKGROUND

Several investigators have observed elevated levels of CRP in individuals with hypertension. Hypertension prevalence varies considerably across ethnic groups. Important questions remain regarding whether the relationship between hypertension and CRP is similar across ethnic and gender subgroups.

METHODS

The MESA participants had CRP levels determined at the baseline clinical examination (N = 6,814). Hypertension, treated as a dichotomous variable (yes/no), was defined as a systolic or diastolic BP > or =140/90 mm Hg or a self-reported history of hypertension and use of antihypertensive medications.

RESULTS

The geometric mean CRP in hypertensive participants was 2.3 +/- 0.07 mg/l compared with 1.6 +/- 0.07 mg/l among normotensive participants (p < 0.0001). The relative difference in CRP levels in hypertensives compared with normotensives was similar regardless of gender (13% in men and 13% in women). Ethnic comparisons showed that Chinese participants had the lowest CRP concentration but the largest difference in CRP by hypertension status (24%). Caucasians and African Americans had 10% to 15% higher CRP levels with hypertension, whereas Hispanics had no significant difference in CRP by hypertension status.

CONCLUSIONS

This study confirms the existence of an independent association between hypertension and inflammation in both men and women. Ethnic group differences were evident, with the strongest association observed in Chinese participants and no difference in CRP levels by hypertension status in Hispanics.