Promotion of photocarcinogenesis by the senescent field and mechanisms for field persistence

暴露在阳光的紫外线(UV)下是皮肤癌的主要原因，皮肤癌导致的死亡人数超过 每年有2万名美国人。退伍军人患皮肤癌的风险增加 在训练和部署期间暴露在阳光下。紫外线照射还会导致光老化，导致细胞 获得一种称为衰老的有丝分裂后表型。除了日光照射外，年龄和药物治疗 免疫抑制剂是皮肤癌发生的最重要的风险因素。在这项提案中，我们将 检查我们新的两组分皮肤癌变模型，该模型将光老化和 免疫抑制对皮肤癌的发展。从历史上看，癌症领域指的是 否则，就会增加患癌症的风险。上皮性癌症领域是 以突变的逐步积累为特征的，最终导致恶变。我们 已经表明，紫外线会诱导以炎症为特征的多焦点皮肤衰老场 可通过成像真皮血红蛋白(Hb)含量进行可视化和测量的血管生成。这 停止紫外线治疗后真皮场持续和扩大，并预测覆盖表皮的位置 克隆性扩增与肿瘤形成。在这个提议中，我们提出真空场也存在，并且 真皮场的主要特征是存在衰老细胞。这些衰老的细胞产生和 分泌特定的促炎、有丝分裂和免疫调节介质，我们认为这些介质可以推动 上覆上皮突变领域的持续发展。然而，免疫系统可以识别 清除衰老细胞(衰老监测)。我们预测这种免疫介导的清除作用 抑制衰老真皮场对肿瘤形成的影响。我们预计这种治疗是通过 免疫抑制药物通过阻断免疫介导的皮肤清除来促进肿瘤的发生 衰老的细胞。转化生长因子-β是紫外线诱导的一种细胞因子 衰老，由衰老的细胞产生。这种转化生长因子-β的产生可以反过来导致诱导 邻近细胞的衰老(旁观者衰老)。我们认为，旁观者的衰老，在一个 免疫抑制设置，提供一种自我维持机制，驱动衰老的场持续 和扩张。最后，并不是所有的免疫抑制剂都有相同的促进皮肤癌的能力。 发展。环孢素A促进皮肤癌的发展，转化生长因子-β的产生，并诱导衰老。 相比之下，西罗莫司对皮肤癌风险的影响有限，已知可以抑制转化生长因子-β的产生，以及 抑制衰老细胞的形成和分泌活动。在这份提案中，我们将确定紫外线是否- 诱导衰老场是皮肤癌发生所必需的，决定是否有免疫抑制作用 治疗促进衰老领域的发展和持久性，并决定转化生长因子-β信号和 旁观者的衰老在这一过程中发挥了核心作用。这将通过三个目标来实现： 目的1：确定感光疗法是否能抑制光致癌和真皮场的持续。 检测感受性治疗和转化生长因子-β信号的缺失是否阻断环孢素A增强环孢素A的能力， 和西罗莫司来抑制紫外线诱导的肿瘤形成。 目的2.应用单细胞RNA测序(ScRNAseq)和真皮全转录组测序 差异表达分析以表征充血和非充血病灶之间的差异。 目的3.确定环孢素A是否抑制衰老监测并促进旁观者 野生型衰老，而西罗莫司抑制旁观者衰老。转化生长因子-β对旁观者的作用 还将对衰老情况进行评估。

Exposure to the ultraviolet (UV) rays of sunlight is the primary cause of skin cancer, which kills greater than 20,000 U.S. individuals each year. Veterans are at increased risk for skin cancer development due to increased sun exposure during training and deployment. UV exposure also causes photoaging that results in cells acquiring a post-mitotic phenotype called senescence. In addition to sun exposure, age and treatment with immunosuppressants are the most significant risk factors for skin cancer development. In this proposal, we will examine our novel 2 component cancer field model of cutaneous carcinogenesis that links photoaging and immunosuppression to skin cancer development. Historically, the cancer field refers to multifocal areas of otherwise normal epithelium that are at increased risk for cancer development. This epithelial cancer field is characterized by the stepwise accumulation of mutations that eventually lead to malignant conversion. We have shown that UV induces a multifocal dermal senescent field that is characterized by inflammatory angiogenesis that can be visualized and measured by imaging the dermal hemoglobin (Hb) content. This dermal field persists & expands following cessation of UV treatments and predicts sites of overlying epidermal clonal expansion & tumor formation. In this proposal, we propose that a dermal field also exists and that the key characteristic of this dermal field is the presence of senescent cells. These senescent cells produce and secrete specific pro-inflammatory, mitogenic and immunomodulatory mediators that we propose drive the continued development of the overlying epithelial mutant field. However, the immune system can recognize and clear senescent cells (senescence surveillance). We predict that this immune-mediated clearance acts to suppress the effects of the senescent dermal field on tumor formation. We expect that treatment with immunosuppressive drugs would promote tumorigenesis by blocking immune-mediated clearance of dermal senescent cells. Transforming growth factor beta (TGF-β) is a cytokine that is necessary for UV-induced senescence and is produced by senescent cells. This TGF-β production can in turn result in the induction of senescence in nearby cells (bystander senescence). We propose that bystander senescence, in an immunosuppressed setting, provides a self-perpetuating mechanism that drives senescent field persistence AND expansion. Finally, not all immunosuppressive agents have the same capacity to promote skin cancer development. Cyclosporine A promotes skin cancer development, TGF-β production, and induces senescence. In contrast, sirolimus has a limited effect on skin cancer risk, is known to suppresses TGF-β production, and suppresses senescent cell formation and secretory activity. In this proposal, we will determine whether the UV- induced senescent field is necessary for skin cancer development, determine whether immunosuppressive therapy promotes senescent field development and persistence, and determine whether TGF-β signaling & bystander senescence play central roles in this process. This will be done in three aims: Aim 1: Determine whether senolytic therapy inhibits photocarcinogenesis and dermal field persistence. Examine whether senolytic therapy and loss of TGF-β signaling block the ability of cyclosporine A to enhance, and sirolimus to suppress, UV-induced tumor formation. Aim 2. Use single cell RNA sequencing (scRNAseq) and dermal whole transcriptome sequencing and differential expression analysis to characterize the differences between hyperemic and non-hyperemic foci. Aim 3. Determine whether cyclosporine A suppresses senescence surveillance and promotes bystander senescence in wildtype while sirolimus acts to suppress bystander senescence. The role of TGF-β on bystander senescence will also be assessed.