Dermal fibroblast/ATF3 control of skin homeostasis

描述（由申请人提供）：外源性损伤，如紫外线暴露，导致与衰老和癌症风险增加相关的皮肤变化。我们最近发现，在真皮成纤维细胞中受损的Notch/CSL信号传导可导致皮肤区域癌变，这是一种重要的临床病症，由多灶性癌前角化细胞病变（如光化性角化病，AK）组成，之前是周围上皮和基质组织中更广泛的变化。在初步研究中，我们发现，在基质重塑和促炎基因上调的AK病变基质中，ATF 3的表达降低。ATF 3是角质形成细胞中具有促肿瘤功能的关键应激反应转录因子。我们的工作假设是ATF 3在真皮细胞中发挥相反的功能，维持正常的皮肤稳态并抑制角质形成细胞肿瘤的进展。 1)我们将测试这一假设，即真皮成纤维细胞表达的ATF 3起着抑制角化细胞肿瘤发展的功能。在我们的初步工作中，我们已经发现具有普遍存在的ATF 3基因缺失的小鼠对发育不良/恶性皮肤肿瘤形成的易感性增加，并且ATF 3-/-真皮成纤维细胞增强弱转化角质形成细胞的致瘤行为。我们将通过对具有真皮成纤维细胞特异性缺失的ATF 3基因的小鼠进行分析来扩展研究结果，并将结果扩展到人类细胞，利用我们开发的一种新的肿瘤扩增体内成像测定法。 2)我们将检验ATF 3参与控制真皮成纤维细胞衰老和CAF活化与受损Notch/CSL信号传导拮抗的假设。基质细胞衰老导致产生诱导旁分泌肿瘤生长刺激的扩散因子。我们已经发现，在真皮成纤维细胞中，许多衰老和CAF（S-CAF）基因通过ATF 3沉默上调，而增加的ATF 3抑制它们的表达。我们将评估ATF 3是否通过与Notch/CSL平行直接结合和/或与其他转录抑制机制协同作用来控制这些基因的表达。 3)我们将检验涉及上调ATF 3表达和/或功能的方法可用于抑制真皮成纤维细胞衰老和/或CAF活化的假设。通过体外测定鉴定的化合物的功效将在体内、动物模型中和通过使用人细胞成像测定来验证。

DESCRIPTION (provided by applicant): Exogenous insults, like UV exposure, lead to skin changes associated with aging and increased cancer risk. We recently showed that compromised Notch/CSL signaling, in dermal fibroblasts can lead to cutaneous field cancerization, an important clinical condition, consisting of multifocal premalignant keratinocyte lesions (like actinic keratosis, AK) preceded by more widespread changes in surrounding epithelial and stromal tissues. In preliminary studies we have found that, in stroma of AK lesions in which matrix remodeling and pro-inflammatory genes are up-regulated, expression of ATF3 is decreased. ATF3 is a key stress response transcription factor with a tumor promoting function in keratinocytes. Our working hypothesis is that ATF3 plays an opposite function in dermal cells, maintaining normal skin homeostasis and suppressing keratinocyte tumor progression. 1) We will test the hypothesis that dermal fibroblast expression of ATF3 plays a suppressive function against keratinocyte tumor development. In our preliminary work we have found that mice with ubiquitous ATF3 gene deletion have increased susceptibility to dysplastic/malignant skin tumor formation and that ATF3 -/- dermal fibroblasts enhance tumorigenic behavior of weakly transformed keratinocytes. We will extend the findings by analysis of mice with dermal fibroblast- specific deletion of the ATF3 gene and extend the results to human cells, utilizing a novel in vivo imaging assay for tumor expansion that we have developed. 2) We will test the hypothesis that ATF3 is involved in control of dermal fibroblast senescence and CAF activation in antagonism with compromised Notch/CSL signaling. Stromal cells senescence results in production of diffusible factors inducing paracrine tumor growth stimulation. We have found that, in dermal fibroblasts, many senescence and CAF (S-CAF) genes are up-regulated by ATF3 silencing, while increased ATF3 suppresses their expression. We will assess whether ATF3 controls expression of these genes by direct binding in parallel with Notch/CSL and/or functioning in concert with other transcription repressing mechanisms. 3) We will test the hypothesis that methods involving up-regulation of ATF3 expression and/or function can be used for suppression of dermal fibroblast senescence and/or CAF activation. Efficacy of compounds identified by in vitro assays will be validated in vivo, in animal models and by use of human cell imaging assays.