Impact of age-related changes of the dermal extracellular matrix on skin cancer

这项拨款申请的主要目的是检验一种新的假说，即皮肤中与年龄相关的变化 细胞外基质(ECM)微环境促进皮肤癌的发生发展。癌症是一种老年病。 例如，角质形成细胞皮肤癌是人类最常见的癌症形式，很少发生在个人身上。 年龄在40岁以下，但在老年人中很常见。 间质结缔组织微环境在上皮性癌中的重要性日益受到重视 承认。然而，自然衰老会导致细胞外基质微环境发生变化的概念 促进癌症的发展几乎没有受到关注。在人类皮肤中，真皮成纤维细胞负责 构成皮肤主体的胶原性细胞外基质的动态平衡。我们最近的研究表明，老年人 真皮成纤维细胞在体内表达一种名为CCN1(CCN家族的第一个成员)的蛋白水平升高 蛋白质)，分泌并与真皮细胞外基质结合。我们发现升高的CCN1上调了许多 与衰老相关的分泌表型(SASP)相关的蛋白质，从而促进真皮连接 组织老化。这些变化包括：1)胶原蛋白水平降低，导致真皮变薄；2) 多种胶原降解酶水平升高，导致细胞外基质碎裂增加；以及3) 多种促炎细胞因子水平升高，导致皮肤发炎。重要的是 所有这些CCN1诱导的变化在活体老化的人皮肤中都很容易观察到。 基于这些考虑，我们建立了一种转基因小鼠模型，在 控制成纤维细胞特异性启动子，这是老年人皮肤中CCN1升高的来源(COL-CCN1TG)。这些 小鼠通过分泌SASP相关基因而表现出真皮ECM微环境的改变。在 转基因小鼠，皮肤薄，皱纹细小，胶原纤维碎裂和混乱，正如观察到的那样 在老化的人类皮肤中。重要的是，这些小鼠表现出很高的皮肤肿瘤形成倾向，由两种- 分期致癌方案。基于这些数据，我们假设与年龄相关的皮肤细胞外基质 微环境促进上皮性肿瘤的发展。 该应用程序将使用一种新的特定细胞类型的双转基因小鼠模型来验证上述假设， 其中，表皮癌基因RAS在皮肤上皮细胞中特异表达，并与衰老相关 真皮细胞外基质微环境是由成纤维细胞特异性表达CCN1产生的。建议进行的研究 将直接研究与年龄相关的真皮细胞外基质微环境促进皮肤的新概念 癌症的发展与上皮癌基因的协同作用，从而可能对该领域产生深远的影响 识别与年龄相关的皮肤微环境是老年人癌症防治的关键 治疗干预的目标。

The major goal of this grant application is to test a novel hypothesis that age-related changes in the dermal extracellular matrix (ECM) microenvironment promote skin cancer development. Cancer is a disease of aging. For example, keratinocyte skin cancer, the most common form of human cancer, rarely occurs in individuals under the age of 40, but very common in the elderly. The importance of stromal connective tissue microenvironment in epithelial cancer is receiving increased recognition. However, the concept that natural aging brings about changes in the ECM microenvironment that promote cancer development has received little attention. In human skin, dermal fibroblasts are responsible for homeostasis of the collagenous ECM, which comprises the bulk of skin. Our recent studies reveal that aged dermal fibroblasts in vivo, express elevated levels of a protein called CCN1 (first member of CCN family proteins), which is secreted and binds to the dermal ECM. We find that elevated CCN1 up-regulates numerous proteins related to senescence-associate secretory phenotype (SASP), and thus promotes dermal connective tissue aging. These alterations include: 1) reduced levels of collagens, which causes dermal thinning; 2) elevated levels of multiple collagen-degrading enzymes, which cause increased fragmentation of ECM; and 3) increased levels of multiple pro-inflammatory cytokines, which contributes to dermal inflammaging. Importantly, all of these CCN1-indced alterations are readily observed in aged human skin in vivo. Based on these considerations, we have created a transgenic mouse model that expresses CCN1 under control of a fibroblast-specific promoter, the source of elevated CCN1 in aged human skin (col-CCN1TG). These mice display alterations of the dermal ECM microenvironment by secretion of SASP-related genes. In the transgenic mice, skin is thin, finely wrinkled, and collagen fibrils are fragmented and disorganized, as observed in aged human skin. Importantly, these mice display a high propensity for skin tumor formation elicited by two- stage carcinogenesis protocol. Based on these data, we hypothesize that age-associated dermal ECM microenvironment promotes epithelial tumor development. This application will test the above hypothesis using a novel cell-type-specific double-transgenic mouse model, in which the epidermal oncogene Ras is specifically expressed in the skin epithelium and aged-associated dermal ECM microenvironment is generated by fibroblast-specific expression of CCN1. The proposed studies will directly investigate the novel concept that age-associated dermal ECM microenvironment promotes skin cancer development in cooperation with epithelial oncogene, and thus may have profound impact on the field of cancer prevention/treatment in the aged by identifying age-associated dermal microenvironment as a key target for therapeutic intervention.