Dynamic expression pattern of Sonic hedgehog in developing cochlear spiral ganglion neurons

Sonic hedgehog (Shh) signaling plays important roles in the formation of the auditory epithelium. However, little is known about the detailed expression pattern of Shh and the cell sources from which Shh is secreted. By analyzing Shh^CreEGFP/+ mice, we found that Shh was first expressed in all cochlear spiral ganglion neurons by embryonic day 13.5, after which its expression gradually decreased from base to apex. By postnatal day 0, it was not detected in any spiral ganglion neurons. Genetic cell fate mapping results also confirmed that Shh was exclusively expressed in all spiral ganglion neurons and not in surrounding glia cells. The basal‐to‐apical wave of Shh decline strongly resembles that of hair cell differentiation, supporting the idea that Shh signaling inhibits hair cell differentiation. Furthermore, this Shh^CreEGFP/+ mouse is a useful Cre line in which to delete floxed genes specifically in spiral ganglion neurons of the developing cochlea. Developmental Dynamics 239:1674–1683, 2010. © 2010 Wiley‐Liss, Inc.     

Hedgehog通路中Ptchl基因在人胃癌中高甲基化状态分析

目的 研究Hedgehog通路中Ptchl基因表达及其甲基化状态在胃癌发生中的变化.方法 分别抽提10例胃癌组织及其癌旁＞3 cm组织和胃癌细胞株AGS的总RNA和基因组DNA.实时定量逆转录多聚酶链反应(QRT-PCR)检测Ptch基因的mRNA表达.应用软件分析Ptchl基因5'调控序列的CpG岛状态,亚硫酸氢盐测序PCR(BSP)分析甲基化水平.结果 对Ptchl mRNAla转录体转录起始位点(计为0点)上游-3950 bp和下游+2050 bp进行CpG岛分析,发现存在两个CpG岛,第1个为-1139 bp～+860 bp,第2个为+875 bp～+1692 bp.以第1个CpG岛的-870 bp～+229 bp区段内的19个CpG位点的BSP测序结果显示,胃癌细胞株AGS全部发生甲基化,胃癌组织中甲基化程度为16%～100%,平均64%±32%,癌旁组织甲基化程度为0%～42%,平均13%±14%,两组问差异有统计学意义(P＜0.05).Spearman秩相关分析发现,Ptchl基因甲基化同其表达呈负相关(r=-0.558,P=0.011).结论 Ptchl基因高甲基化参与胃癌的发生,可能为胃癌新的肿瘤标志物.     

Non-cell-autonomous signaling by Shh in tumors: challenges and opportunities for therapeutic targets

Importance of the field: The Hedgehog (Hh) pathway is required during many developmental events; in adults the Hedgehog pathway is involved in the maintenance of several stem cell niches. It is therefore not surprising that aberrantly regulated Hh pathway activity can cause birth defects in the developing organism, as well as neoplastic disease later in life.

Areas covered in this review: As a consequence of the involvement in pathogenesis, the Hh pathway components are subject to an intense scrutiny as potential targets for therapeutic agents. We aim to provide an overview of the biology of the Hh proteins and the cellular response, in conjunction with potential therapeutic interventions.

What the reader will gain: Specifically, we focus on the recently discovered non-cell-autonomous Shh signaling used by tumors and the implications of this for the design of treatment strategies. This should provide the reader with up-to-date knowledge on the role of the Hh pathway in tumor progression and the options to treat these malignancies.

Take home message: An important concept that we advocate in this review is the need to recognize the need to target both the stromal and the tumor compartment in malignancies that rely on paracrine Shh signaling.     

Investigational Notch and Hedgehog inhibitors – therapies for cardiovascular disease

Introduction: During the past decade, a variety of Notch and Hedgehog pathway inhibitors have been developed for the treatment of several cancers. An emerging paradigm suggests that these same gene regulatory networks are often recapitulated in the context of cardiovascular disease and may now offer an attractive target for therapeutic intervention.

Areas covered: This article briefly reviews the profile of Notch and Hedgehog inhibitors that have reached the preclinic and clinic for cancer treatment and discusses the clinical issues surrounding targeted use of these inhibitors in the treatment of vascular disorders.

Expert opinion: Preclinical and clinical data using pan-Notch inhibitors (γ-secretase inhibitors) and selective antibodies to preferentially target notch receptors and ligands have proven successful but concerns remain over normal organ homeostasis and significant pathology in multiple organs. By contrast, the Hedgehog-based drug pipeline is rich with more than a dozen Smoothened (SMO) inhibitors at various stages of development. Overall, refined strategies will be necessary to harness these pathways safely as a powerful tool to disrupt angiogenesis and vascular proliferative phenomena without causing prohibitive side effects already seen with cancer models and patients.     

Discovery and preclinical development of vismodegib

Introduction: Vismodegib is the first Hedgehog (Hh) pathway inhibitor approved in the US for the treatment of adults with metastatic or locally advanced basal cell carcinoma (BCC). It was approved by the US FDA on 30 January 2012, and by the European Commission on 12 July 2013, for the treatment of adult patients with symptomatic metastatic BCC, or locally advanced BCC inappropriate for surgery or radiotherapy. Vismodegib selectively inhibits the Hh signaling pathway, binding to and inhibiting a critical signal-transducing component of the pathway, Smoothened (SMO). Vismodegib was discovered by Genentech, Inc., under a collaboration agreement with Curis, Inc.

Areas covered: This article reviews the development of vismodegib from its discovery, preclinical pharmacology and validation to the clinical pharmacokinetics and validation in Phase I and II clinical investigations. We also provide a survey of other Hh pathway inhibitors in clinical development.

Expert opinion: The authors’ experience in target-based drug discovery suggests that vismodegib’s path to the clinic deserves some reflection to identify key steps that have contributed to its success. Targeting the Hh pathway with vismodegib blocks the abberant signaling caused by mutational inactivation of the negative regulator PTCH1 or mutational activation of SMO. Vismodegib gives physicians a treatment option for patients with locally advanced or metastatic BCC for whom surgery or radiation is not recommended.     

TRARESA: a tissue microarray-based hospital system for biomarker validation and discovery

Formalin fixed and paraffin embedded tissue (FFPE) collections in pathology departments are the largest resource for retrospective biomedical research studies. Based on the literature analysis of FFPE related research, as well as our own technical validation, we present the Translational Research Arrays (TRARESA), a tissue microarray centred, hospital based, translational research conceptual framework for both validation and/or discovery of novel biomarkers. TRARESA incorporates the analysis of protein, DNA and RNA in the same samples, correlating with clinical and pathological parameters from each case, and allowing (a) the confirmation of new biomarkers, disease hypotheses and drug targets, and (b) the postulation of novel hypotheses on disease mechanisms and drug targets based on known biomarkers. While presenting TRARESA, we illustrate the use of such a comprehensive approach. The conceptualisation of the role of FFPE-based studies in translational research allows the utilisation of this commodity, and adds to the hypothesis-generating armamentarium of existing high-throughput technologies.