Physical and functional CSL-p53 interactions underlie control of cancer stromal cell evolution [ChIP-seq]. Homo sapiens

Senescence of stromal fibroblasts has been linked to establishment of cancer associated fibroblasts (CAF) and aging-associated increase of tumors. However, in clinically occurring carcinomas, density and proliferation of CAFs are frequently increased rather than decreased. We previously showed that genetic deletion or down-modulation of the canonical Notch effector CSL/RBP-Jκ in skin dermal fibroblasts is sufficient for CAF activation with consequent development of multifocal keratinocyte tumors. We now show that CSL deletion or knockdown induces senescence of primary fibroblasts derived from dermis, oral mucosa, breast and lung. CSL functions in these cells as a constitutive direct repressor of multiple senescence- and CAF-effector genes. At the same time, it physically interacts with p53, repressing its activity, and p53 activation provides a failsafe mechanism against compromised CSL function. Concomitant loss of CSL and p53 overcomes fibroblast senescence, enhances expression of CAF effector genes and, in vivo, promotes tumour and stromal cell expansion. Together, the findings support a CAF activation/stromal evolution model under convergent CSL/p53 control. Overall design: Examination of genome-wide CSL binding sites in primary human dermal fibroblasts usinf two different antibodies against CSL

基质成纤维细胞的衰老已被证实与癌症相关成纤维细胞（cancer associated fibroblasts, CAF）的形成以及衰老相关的肿瘤发生风险升高存在关联。然而，在临床检出的癌组织中，CAFs的密度与增殖能力往往呈升高趋势，而非降低。我们此前的研究表明，在皮肤真皮成纤维细胞中，经典Notch效应因子CSL/RBP-Jκ的基因敲除或下调，足以激活CAF并由此诱发多灶性角质形成细胞肿瘤。本研究证实，CSL的敲除或敲低会诱导源自真皮、口腔黏膜、乳腺及肺组织的原代成纤维细胞发生衰老。CSL在这些细胞中作为组成型直接阻遏因子，对多个衰老相关及CAF效应基因发挥直接抑制作用。与此同时，它可与p53发生物理相互作用并抑制其活性，而p53的激活则为CSL功能受损提供了一种失效保护机制。同时缺失CSL与p53可逆转成纤维细胞的衰老状态，增强CAF效应基因的表达，并在体内促进肿瘤与基质细胞的扩增。综上，本研究结果支持一种在CSL与p53协同调控下的CAF激活/基质演化模型。
整体实验设计：使用两种针对CSL的不同抗体，检测原代人真皮成纤维细胞中的全基因组CSL结合位点。