Dermal fibroblast/ATF3 control of skin homeostasis

描述（由申请人提供）：外源性损伤，如紫外线照射，会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，真皮成纤维细胞中的Notch/CSL信号受损可导致皮场癌变，这是一种重要的临床症状，包括多灶性癌前角质细胞病变（如光化性角化病，AK），在此之前周围上皮和间质组织发生更广泛的变化。我们在前期研究中发现，在基质重塑和促炎基因上调的AK病变间质中，ATF3的表达降低。ATF3是一个关键的应激反应转录因子，在角化细胞中具有促肿瘤功能。我们的工作假设是ATF3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化细胞肿瘤的进展。1)我们将验证真皮成纤维细胞表达ATF3对角化细胞肿瘤发展具有抑制作用的假设。在我们的初步工作中，我们发现普遍存在ATF3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ATF3 -/-真皮成纤维细胞增强弱转化角化细胞的致瘤性行为。我们将通过分析具有真皮成纤维细胞特异性缺失ATF3基因的小鼠来扩展研究结果，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展体内成像检测方法。2)我们将验证ATF3参与控制真皮成纤维细胞衰老的假设，并通过Notch/CSL信号通路受损拮抗CAF激活。基质细胞衰老导致扩散因子的产生，诱导旁分泌肿瘤生长。我们发现，在真皮成纤维细胞中，许多衰老和CAF （S-CAF）基因通过ATF3沉默而上调，而ATF3增加则抑制其表达。我们将评估ATF3是否通过与Notch/CSL平行的直接结合和/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)我们将验证涉及上调ATF3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激活的假设。通过体外测定确定的化合物的功效将在体内、动物模型和人类细胞成像测定中得到验证。

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.