P4-04-02: Smoothened Function as a G-Protein Coupled Receptor in Mammary Epithelial Cells

Background

Hedgehog signaling orchestrates many key developmental processes, including cell fate determination and tissue patterning in the embryo, as well as tissue homeostasis and stem cell maintenance in the adult. Aberrant hedgehog signaling has been implicated in several cancers including skin, brain, prostate and breast. Previous work in our laboratory demonstrated that overexpression of activated Smoothened (SMO), a key effector in hedgehog signaling, leads to mammary hyperplasia, and is overexpressed in DCIS and IBCs.

Consistent with recent data, we now provide evidence that SMO signals via Gαi proteins in the mouse mammary gland.

Hypothesis: Smoothened promotes mammary gland proliferation by functioning as a G-protein coupled receptor(GPCR) and couples to one or more members of the PTX-sensitive Gαi family of heterotrimeric G-protein subunits.

Experimental Design and Methods: Expression of Gαi subunit(s) was tested by qRT-PCR & immunofluorescence microscopy of mammary epithelial cells (MECs) and whole mammary glands from SMO and WT mice. We analyzed mammary glands from single Gαi subunit null mice for developmental abnormalities. Genetic studies are underway in which SMO mice are crossed to Gαil2&3 null mice.

To elucidate downstream signaling events triggered by SMO activation, we are treating SMO derived MECs cultured in a 3D matrix and whole gland organ cultures with inhibitors of Gαi effector molecules and assessing proliferation status. We will also employ GTPγS binding assays using primary MECs from SMO overexpressing mice to test whether SMO can activate Gαi proteins in mammary gland epithelium.

Results and Discussion: Treatment of MMTV-Cre dependent SMO hyperplasias with pertussis toxin (PTX), a potent inhibitor of Gαi family of G-protein signaling, significantly attenuates mammary gland hyperproliferation. This result supports the hypothesis that Smoothened functions as a GPCR interacting with one or more members of the Gαi family.

We have now found that Gαi2 and Gαi3 null mice display an increased number of terminal end buds and a more completely filled fat pad relative to WT control littermates.

Our data suggest that SMO-expressing cells induce proliferation of neighboring WT cells and that low-level proliferation in SMO-expressing cells is not affected by PTX.

qPCR data indicates that Gαi1 is the most abundant transcript in sorted MECs which overexpress SMO and that the Notch signaling pathway may be activated.

While our mechanistic data thus far mostly comprises transcriptional analyses coupled with pharmacological inhibition, they offer insight as to which pathways may be regulated by SMO activation. Genetic crosses between the SMO and Gαi null mice should provide evidence that these two proteins interact in the developing mammary gland. When associated with biochemical data, these studies ought to provide functional insight into the mechanism behind SMO-driven mammary hyperplasias.

This work offers potential clinical implications towards breast cancer treatment as there exist therapeutic agents targeting the hedgehog signaling pathway in clinical trials that were developed by solely testing their ability to inhibit GLI1/2-mediated transcription. Our data identify targets for intervention other than the GLI transcription factors.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-04-02.

Idiotype vaccines for human B-cell malignancies

After twenty years of use in humans, customized idiotypic vaccination yet remains a non-approved, experimental therapeutic option for patients with lymphoma and myeloma. Potentially applicable to all B-cell malignancies whose cells express a clonal immunoglobulin or its epitopes on their surface, this treatment is designed to prevent disease recurrence or progression. Mostly used in follicular lymphoma patients so far, idiotype vaccines have clearly shown biological efficacy, clinical efficacy and clinical benefit in this setting, although no study aiming at regulatory approval of the procedure has been able to meet its main clinical endpoints. In mantle cell lymphoma, only biological efficacy has been proven for idiotypic vaccination, while in multiple myeloma a limited number of studies support the notion of biological and perhaps even clinical efficacy, although no credible evidence of clinical benefit has still emerged. Idiotype vaccines have been produced and administered in a number of substantially different manners. Therefore, the results of most clinical trials cannot be easily compared, and even less pooled together in meaningful meta-analyses. A more creative and yet scientifically sound way to design clinical trials of customized active immunotherapies will be key to the future development of idiotype vaccines, particularly considering that we currently lack any clinical or biological indicator to possibly predict which patients are more likely to respond to idiotypic vaccination from an immunologic point of view. This review aims at summarizing the multifaceted success achieved by idiotype vaccines, as well as at outlining the challenges awaiting them in the near future: how to improve feasibility, immunogenicity and efficacy, as well as how to confirm benefit and gain regulatory approval.

The Role of Smoothened in Mammary Gland Development and Breast Cancer

The hedgehog (Hh) signaling pathway is a critical pathway for development and is known to influence proliferation, cell fate, morphogenesis, and stem cell self-renewal. Mutations activating Hh signaling have been found in a wide variety of cancers, and it is estimated that up to 25% of all tumors display misregulated Hh signaling. Smoothened (Smo), a seven pass transmembrane protein is the Hh signaling pathway's primary effector and its sole non-redundant member. In a recent study, Smo was found to be over-expressed in 70% of ductal carcinom in-situ (DCIS) lesions and 30% of invasive breast carcinomas (IBC). Despite the implication of this protein in breast cancer, little is known about its role in normal mammary gland development.In order to understand the role of Smo in mammary gland development we have performed phenotypic analyses of a conditional mouse model expressing constitutively activated Smo under the control of a mammary gland selective Cre recombinase. We show that activation of the Hh pathway results in increased proliferation starting around five weeks of age that leads to a dramatic increase in branching and budding of the mammary gland at around ten weeks of age. In addition, immunostaining using the ductal markers Na-K-Cl Co-transporter 1 (NKCC1) and aquaporin 5 (AQP5) suggests alterations in cell fate. Finally, these mice exhibit changes in the stroma surrounding the mammary ducts including an increase in collagen deposition. Gene profiling studies show upregulation of several genes, including targets of the Notch pathway, in ten-week-old virgin mammary glands from the constitutively active conditional Smo mouse model when compared to control. Surprisingly, canonical downstream Hh target genes like Patched and Gli were not found to be upregulated. These data in conjunction with recent published studies suggest that Smo activation in the mammary gland may be acting via a non-canonical mechanism to produce the observed hyper-branched and budded phenotype. Preliminary studies indicate that Smoothened may be functioning as a G-protein coupled receptor (GPCR) via a pertussis-toxin sensitive mechanism. Interestingly, constituitive Smo activity does not appear to alter cyclic AMP (cAMP) levels as recently reported in Drosophila indicating that mammalian Smo may be acting via a different mechanism.In addition to these gain-of-function studies, experiments are underway utilizing a conditional null Smo mouse model (loss-of-function) to determine if there is a requirement for Hh pathway activation in normal mammary gland development. Preliminary analysis indicates that partial loss of Smo in mammary gland cells leads to impaired ductal elongation and reduced branching.Future studies will include the generation of mammary gland chimeras to study the possible paracrine interactions between Smo over-expressing and wild type cells. Additionally, experiments are under way to elucidate the mechanism of Smo's GPCR function in the mammary gland.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2164.

[Idiotype vaccines in the treatment of follicular lymphoma: current status and future perspectives]

Follicular lymphoma is the second most prevalent non-Hodgkin lymphoma, representing 20% of all lymphomas. Follicular lymphoma is an indolent disease with a slow progression in which, although exhibiting a good response to treatment, relapse is very frequent and complete remission is not easy to maintain. Therefore, the disease is regarded as incurable. The search for new therapeutic strategies, together with a better understanding of the immune system, has led to the emergence of a new treatment named immunotherapy. Follicular lymphoma is a malignancy suitable for this kind of treatment given the fact that it is characterized by presenting a unique tumour-specific antigen: the idiotype of the monoclonal immunoglobulin displayed on the membrane of tumour cells. Several studies have been conducted to test immunotherapy as complementary to conventional treatment. In a previous study by our group, a clear benefit was evident is obtained after idiotypic vaccination, when an adequate immunization of the patient is obtained, in comparison to chemotherapy alone. In this sense, analysis is needed of whether idiotypic vaccination can produce not only long-lasting and complete remission, but even cure. It would be of great interest to consider an optimisation of the experimental design of clinical trials, an improvement of vaccine production, and the study of the molecular mechanisms of the tumour cell which modify the target immunoglobulin.

A DnaJ protein, apobec-1-binding protein-2, modulates apolipoprotein B mRNA editing

Mammalian homologues of DnaJ proteins, also known as Hsp40 proteins, are co-chaperonins that complement Hsp70 chaperone function. Using the yeast two-hybrid system, we cloned an apolipoprotein (apo) B mRNA editing complementation protein, called apobec-1-binding protein-2 (ABBP-2), and found that it is a Class II DnaJ homologue. ABBP-2 binds to apobec-1, the mammalian apoB mRNA editase, via its J domain and neighboring G/F domain. It is a ubiquitously expressed protein, and, by transfection analysis of GFP-ABBP-2, we found that the protein is located in both the nucleus and cytosol of transfected cells, with predominance in the nucleus. Down-regulation of ABBP-2 expression in cultured cells inhibits endogenous apobec-1-mediated apoB mRNA editing. Like other Hsp40 proteins, ABBP-2 binds to Hsp70 and has ATPase-stimulating activity. Apobec-1-mediated apoB mRNA editing activity of in vitro tissue extracts requires the presence of Hsp70/ABBP-2. Although exogenously added ATP is not required for editing activity, removal of the endogenous ATP present in these extracts, which disrupts ABBP-2-Hsp70 interaction, completely inhibits editing. ABBP-2 differs from previously described auxiliary proteins (ABBP-1, ACF, and GRY-RBP) in that it does not contain any RNA recognition motifs. Not only is ABBP-2 required for efficient apoB mRNA editing, this newly discovered apobec-1-binding protein may help determine the subcellular distribution and trafficking of apobec-1 via its interaction with the chaperonin Hsp70.

[Ongoing health management control by cost monitoring through tracer indicators]

OBJECTIVE

To determine the operational cost of a hospital's surgical unit, compare those results with standards, and determine the incidence of the costs; to produce an effective methodology for this purpose that can be applied to all kinds of medical units using any low-cost widely available computer database system, with that methodology being utilized for ongoing management control.

METHODS

This study was carried out in 1999 in the Orthopedics and Traumatology Unit of the "Domingo Funes" Public Hospital, in the province of Córdoba, Argentina. Of the 817 patients who underwent diagnostic or therapeutic procedures in that unit during the year, we selected the 154 of them who were hospitalized and required surgical or instrumental procedures. The study used the tracer event method described by Kessner. Through a consensus process, medical specialists and health economists selected and defined these indicators, which were categorized in relation to their complexity (high, medium, limited, or none). Direct and indirect costs were assessed in order to study their contribution to total cost. Total cost was estimated using nine variables that were applied to the different tracer events.

RESULTS

The largest portion of total cost, both real and standard, was based on the "bed-day" variable. Of this bed-day cost for all tracer events, 51.2% was due to an indirect cost of "social hospitalization" (keeping patients hospitalized for such reasons as transportation difficulties or delays in receiving requested medical supplies) and 48.8% to a direct cost of true therapeutic hospitalization. This bed-day cost was 117% higher for the real costs as compared to the standard costs. The indirect costs of social hospitalization and of therapeutic supplies made up nearly half of the total real cost. Excluding the indirect costs, the real cost of all the tracer events exceeded the standard cost by only 6.4%. Including the indirect costs of social hospitalization and of therapeutic supplies, the real cost exceeded the standard cost by 39.8%. The amount spent on medical staff and support personnel represented just 11.5% of the total cost.

DISCUSSION

Suggestions are provided in various areas, including solutions for the high cost of social hospitalization and therapeutic supplies, the cost-control benefits of creating protocols for procedures and treatments, and the rational utilization of technology in order to improve efficiency and reduce risks. The wider application of this procedure is recommended for cost-management control in all hospital units carrying out surgery or other medical procedures.

New 3-[4-(aryl)piperazin-1-yl]-1-(benzo[b]thiophen-3-yl)propane derivatives with dual action at 5-HT1A serotonin receptors and serotonin transporter as a new class of antidepressants

A series of new 3-[4-(aryl)piperazin-1-yl]-1-(benzo[b]thiophen-3-yl)propane derivatives were synthesized in an attempt to find a new class of antidepressant drugs with dual activity at 5-HT1A serotonin receptors and serotonin transporter. Title compounds were evaluated for in vitro activity on 5-HT1A receptor and 5-HT transporter. They show high nanomolar affinity for both activities, and in particular, compounds 1-(5-chlorobenzo[b]thiophen-3-yl)-3-[4-(2-methoxyphenyl)piperazin-1-yl]propan-1-ol (7) and 1-(5-fluorobenzo[b]thiophen-3-yl)-3-[4-(2-methoxyphenyl)piperazin-1-yl]propan-1-ol (8) show values (nM) of K(i)=30 and 2.3 for 5-HT1A receptors and K(i)=30 and 12 for serotonin transporters, respectively. In GTPgammaS binding assays, compound 8 revealed antagonist properties to 5-HT1A receptors. Such a pharmacological profile could lead to potent antidepressant agents with new dual mechanism of action.

Realtime ultrasound diagnosis over a wide-area network (WAN) using off-the-shelf components

A trial system was developed for relaying realtime ultrasound images from an obstetric referral centre, the Maitland Hospital, to a tertiary-care centre, the John Hunter Hospital in Newcastle. The sites were approximately 30 km apart and connected by a microwave link at 2 Mbit/s. The pilot study demonstrated the feasibility of realtime ultrasound transmission using commonly available components.