Targeting HCV Entry For Development of Therapeutics

Recent progress in defining the molecular mechanisms of Hepatitis C Virus (HCV) entry affords the opportunity to exploit new viral and host targets for therapeutic intervention. Entry inhibitors would limit the expansion of the infected cell reservoir, and would complement the many replication inhibitors now under development. The current model for the pathway of entry involves the initial docking of the virus onto the cell surface through interactions of virion envelope and associated low density lipoproteins (LDL) with cell surface glycosaminoglycans and lipoprotein receptors, followed by more specific utilization with other hepatocyte membrane proteins: Scavenger Receptor Class B type 1 (SR-BI), CD81, Claudin 1 (CLDN1) and Occludin (OCLN). The use of blockers of these interactions, e.g. specific antibodies, suggests that inhibition of any one step in the entry pathway can inhibit infection. Despite this knowledge base, the tools for compound screening, HCV pseudoparticles (HCVpp) and cell culture virus (HCVcc), and the ability to adapt them to industrial use are only recently available and as a result drug discovery initiatives are in their infancy. Several therapies aiming at modulating the virus envelope to prevent host cell binding are in early clinical testing. The first test case for blocking a cellular co-receptor is an SR-BI modulator. ITX 5061, an orally active small molecule, targets SR-BI and has shown potent antiviral activity against HCVpp and HCVcc. ITX 5061 has exhibited good safety in previous clinical studies, and is being evaluated in the clinic in chronic HCV patients and patients undergoing liver transplantation. Entry inhibitors promise to be valuable players in the future development of curative therapy against HCV

Effect of scavenger receptor BI antagonist ITX5061 in patients with hepatitis C virus infection undergoing liver transplantation

Hepatitis C virus (HCV) entry inhibitors have been hypothesized to prevent infection of the liver after transplantation. ITX5061 is a Scavenger Receptor B-I (SR-BI) antagonist that blocks HCV entry and infection in vitro. We assessed the safety and efficacy of ITX5061 to limit HCV infection of the graft. The study included 23 HCV infected patients undergoing liver transplantation. The first 13 "control" patients did not receive drug. The subsequent 10 patients received ITX5061 150 mg immediately pre- and post-transplant, and daily for 1 week thereafter. ITX5061 pharmacokinetics and plasma HCV RNA were quantified. Viral genetic diversity was measured by ultradeep pyrosequencing. ITX5061 was well tolerated with measurable plasma concentrations during therapy. Whilst the median HCV RNA reduction was greater in ITX treated patients at all time points in the first week after transplantation there was no difference in the overall change in the area over the HCV RNA curve in the 7-day treatment period. However, in genotype 1 infected patients treatment was associated with a sustained reduction in HCV RNA levels compared to the control group (area over the HCV RNA curve analysis, p=0.004). Ultradeep pyrosequencing revealed a complex and evolving pattern of HCV variants infecting the graft during the first week. ITX5061 significantly limited viral evolution where the median divergence between day 0 and day 7 was 3.5% in the control group compared to 0.1% in the treated group.CONCLUSIONS: ITX5061 reduces plasma HCV RNA post transplant notably in genotype 1 infected patients and slows viral evolution. Following liver transplantation the likely contribution of extrahepatic reservoirs of HCV necessitates combining entry inhibitors such as ITX5061 with inhibitors of replication in future studies. Clinicaltrials.gov NCT01292824. This article is protected by copyright. All rights reserved.</p

Wnt-reporter expression pattern in the mouse intestine during homeostasis

<p>Abstract</p> <p>Background</p> <p>The canonical Wnt signaling pathway is a known regulator of cell proliferation during development and maintenance of the intestinal epithelium. Perturbations in this pathway lead to aberrant epithelial proliferation and intestinal cancer. In the mature intestine, proliferation is confined to the relatively quiescent stem cells and the rapidly cycling transient-amplifying cells in the intestinal crypts. Although the Wnt signal is believed to regulate all proliferating intestinal cells, surprisingly, this has not been thoroughly demonstrated. This important determination has implications on intestinal function, especially during epithelial expansion and regeneration, and warrants an extensive characterization of Wnt-activated cells.</p> <p>Methods</p> <p>To identify intestinal epithelial cells that actively receive a Wnt signal, we analyzed intestinal Wnt-reporter expression patterns in two different mouse lines using immunohistochemistry, enzymatic activity, <it>in situ </it>hybridization and qRT-PCR, then corroborated results with reporter-independent analyses. Wnt-receiving cells were further characterized for co-expression of proliferation markers, putative stem cell markers and cellular differentiation markers using an immunohistochemical approach. Finally, to demonstrate that Wnt-reporter mice have utility in detecting perturbations in intestinal Wnt signaling, the reporter response to gamma-irradiation was examined.</p> <p>Results</p> <p>Wnt-activated cells were primarily restricted to the base of the small intestinal and colonic crypts, and were highest in numbers in the proximal small intestine, decreasing in frequency in a gradient toward the large intestine. Interestingly, the majority of the Wnt-reporter-expressing cells did not overlap with the transient-amplifying cell population. Further, while Wnt-activated cells expressed the putative stem cell marker Musashi-1, they did not co-express DCAMKL-1 or cell differentiation markers. Finally, gamma-irradiation stimulated an increase in Wnt-activated intestinal crypt cells.</p> <p>Conclusion</p> <p>We show, for the first time, detailed characterization of the intestine from Wnt-reporter mice. Further, our data show that the majority of Wnt-receiving cells reside in the stem cell niche of the crypt base and do not extend into the proliferative transient-amplifying cell population. We also show that the Wnt-reporter mice can be used to detect changes in intestinal epithelial Wnt signaling upon physiologic injury. Our findings have an important impact on understanding the regulation of the intestinal stem cell hierarchy during homeostasis and in disease states.</p

Quality of life after patient-initiated vs physician-initiated response to symptom monitoring:the SYMPRO-Lung trial

BackgroundPrevious studies using patient-reported outcomes measures (PROMs) to monitor symptoms during and after (lung) cancer treatment used alerts that were sent to the health-care provider, although an approach in which patients receive alerts could be more clinically feasible. The primary aim of this study was to compare the effect of weekly PROM symptom monitoring via a reactive approach (patient receives alert) or active approach (health-care provider receives alert) with care as usual on health-related quality of life (HRQOL) at 15 weeks after start of treatment in lung cancer patients.MethodsThe SYMPRO–Lung trial is a multicenter randomized controlled trial using a stepped wedge design. Stage I-IV lung cancer patients in the reactive and active groups reported PROM symptoms weekly, which were linked to a common alerting algorithm. HRQOL was measured by the EORTC QLQ-C30 at baseline and after 15 weeks. Linear regression analyses and effect size estimates were used to assess mean QOL–C30 change scores between groups, accounting for confounding.ResultsA total of 515 patients were included (160 active group, 89 reactive group, 266 control group). No differences in HRQOL were observed between the reactive and active group (summary score: unstandardized beta [B] = 0.51, 95% confidence interval [CI] = -3.22 to 4.24, Cohen d effect size [ES] = 0.06; physical functioning: B = 0.25, 95% CI = -5.15 to 4.64, ES = 0.02). The combined intervention groups had statistically and clinically significantly better mean change scores on the summary score (B = 4.85, 95% CI = 1.96 to 7.73, ES = 0.57) and physical functioning (B = 7.00, 95% CI = 2.90 to 11.09, ES = 0.71) compared with the control group.ConclusionsWeekly PRO symptom monitoring statistically and clinically significantly improves HRQOL in lung cancer patients. The logistically less intensive, reactive approach may be a better fit for implementation

Oncogenic Function of DACT1 in Colon Cancer through the Regulation of β-catenin

The Wnt/β-catenin signaling pathway plays important roles in the progression of colon cancer. DACT1 has been identified as a modulator of Wnt signaling through its interaction with Dishevelled (Dvl), a central mediator of both the canonical and noncanonical Wnt pathways. However, the functions of DACT1 in the WNT/β-catenin signaling pathway remain unclear. Here, we present evidence that DACT1 is an important positive regulator in colon cancer through regulating the stability and sublocation of β-catenin. We have shown that DACT1 promotes cancer cell proliferation in vitro and tumor growth in vivo and enhances the migratory and invasive potential of colon cancer cells. Furthermore, the higher expression of DACT1 not only increases the nuclear and cytoplasmic fractions of β-catenin, but also increases its membrane-associated fraction. The overexpression of DACT1 leads to the increased accumulation of nonphosphorylated β-catenin in the cytoplasm and particularly in the nuclei. We have demonstrated that DACT1 interacts with GSK-3β and β-catenin. DACT1 stabilizes β-catenin via DACT1-induced effects on GSK-3β and directly interacts with β-catenin proteins. The level of phosphorylated GSK-3β at Ser9 is significantly increased following the elevated expression of DACT1. DACT1 mediates the subcellular localization of β-catenin via increasing the level of phosphorylated GSK-3β at Ser9 to inhibit the activity of GSK-3β. Taken together, our study identifies DACT1 as an important positive regulator in colon cancer and suggests a potential strategy for the therapeutic control of the β-catenin-dependent pathway

RNA interference approaches for treatment of HIV-1 infection

HIV/AIDS is a chronic and debilitating disease that cannot be cured with current antiretroviral drugs. While combinatorial antiretroviral therapy (cART) can potently suppress HIV-1 replication and delay the onset of AIDS, viral mutagenesis often leads to viral escape from multiple drugs. In addition to the pharmacological agents that comprise cART drug cocktails, new biological therapeutics are reaching the clinic. These include gene-based therapies that utilize RNA interference (RNAi) to silence the expression of viral or host mRNA targets that are required for HIV-1 infection and/or replication. RNAi allows sequence-specific design to compensate for viral mutants and natural variants, thereby drastically expanding the number of therapeutic targets beyond the capabilities of cART. Recent advances in clinical and preclinical studies have demonstrated the promise of RNAi therapeutics, reinforcing the concept that RNAi-based agents might offer a safe, effective, and more durable approach for the treatment of HIV/AIDS. Nevertheless, there are challenges that must be overcome in order for RNAi therapeutics to reach their clinical potential. These include the refinement of strategies for delivery and to reduce the risk of mutational escape. In this review, we provide an overview of RNAi-based therapies for HIV-1, examine a variety of combinatorial RNAi strategies, and discuss approaches for ex vivo delivery and in vivo delivery

The Wnt-dependent signaling pathways as target in oncology drug discovery

Our current understanding of the Wnt-dependent signaling pathways is mainly based on studies performed in a number of model organisms including, Xenopus, Drosophila melanogaster, Caenorhabditis elegans and mammals. These studies clearly indicate that the Wnt-dependent signaling pathways are conserved through evolution and control many events during embryonic development. Wnt pathways have been shown to regulate cell proliferation, morphology, motility as well as cell fate. The increasing interest of the scientific community, over the last decade, in the Wnt-dependent signaling pathways is supported by the documented importance of these pathways in a broad range of physiological conditions and disease states. For instance, it has been shown that inappropriate regulation and activation of these pathways is associated with several pathological disorders including cancer, retinopathy, tetra-amelia and bone and cartilage disease such as arthritis. In addition, several components of the Wnt-dependent signaling pathways appear to play important roles in diseases such as Alzheimer’s disease, schizophrenia, bipolar disorder and in the emerging field of stem cell research. In this review, we wish to present a focused overview of the function of the Wnt-dependent signaling pathways and their role in oncogenesis and cancer development. We also want to provide information on a selection of potential drug targets within these pathways for oncology drug discovery, and summarize current data on approaches, including the development of small-molecule inhibitors, that have shown relevant effects on the Wnt-dependent signaling pathways

The Interleukin-6 inflammation pathway from cholesterol to aging – Role of statins, bisphosphonates and plant polyphenols in aging and age-related diseases

We describe the inflammation pathway from Cholesterol to Aging. Interleukin 6 mediated inflammation is implicated in age-related disorders including Atherosclerosis, Peripheral Vascular Disease, Coronary Artery Disease, Osteoporosis, Type 2 Diabetes, Dementia and Alzheimer's disease and some forms of Arthritis and Cancer. Statins and Bisphosphonates inhibit Interleukin 6 mediated inflammation indirectly through regulation of endogenous cholesterol synthesis and isoprenoid depletion. Polyphenolic compounds found in plants, fruits and vegetables inhibit Interleukin 6 mediated inflammation by direct inhibition of the signal transduction pathway. Therapeutic targets for the control of all the above diseases should include inhibition of Interleukin-6 mediated inflammation

What does the structure-function relationship of the HIV-1 Tat protein teach us about developing an AIDS vaccine?

The human immunodeficiency virus type 1 (HIV-1) trans-activator of transcription protein Tat is an important factor in viral pathogenesis. In addition to its function as the key trans-activator of viral transcription, Tat is also secreted by the infected cell and taken up by neighboring cells where it has an effect both on infected and uninfected cells. In this review we will focus on the relationship between the structure of the Tat protein and its function as a secreted factor. To this end we will summarize some of the exogenous functions of Tat that have been implicated in HIV-1 pathogenesis and the impact of structural variations and viral subtype variants of Tat on those functions. Finally, since in some patients the presence of Tat-specific antibodies or CTL frequencies are associated with slow or non-progression to AIDS, we will also discuss the role of Tat as a potential vaccine candidate, the advances made in this field, and the importance of using a Tat protein capable of eliciting a protective or therapeutic immune response to viral challenge