RIPK4拮抗Raf1抑制皮肤鳞状细胞癌形成的作用及机制研究

Cutaneous squamous cell carcinoma is characterized by excessive proliferation and low differentiation of squamous cells. However, the pathogenesis and underlying molecular mechanism of cutaneous squamous cell carcinoma remains poorly understood. Raf1 protein is the essential component of Ras/MAPK signaling cascade, whose deregulation is strongly associated with skin tissue homeostasis and carcinogenesis. Our previous study indicated that RIPK4 (Receptor-interacting protein kinase 4), a novel serine/threonine kinase, could suppress skin carcinogenesis by enhancing epidermal differentiation and binding Raf1. To decipher the underlying cellular mechanism, we will analyze epidermal differentiation, cell proliferation and cell apoptosis in RIPK4 conditional knockout mice. We will further characterize the interaction between RIPK4 and Raf1 and decipher the molecular mechanisms whereby RIPK4 governs epidermal homeostasis and skin carcinogenesis. The results of this project will shed light on the elaborating mechanism and therapeutic targets of skin squamous cell carcinoma.

皮肤鳞状细胞癌的组织学特征是鳞状细胞的过度增殖和分化水平的降低。目前，皮肤鳞状细胞癌具体的发病原因和机制尚不清楚，早期诊治缺乏针对性。Raf1是Ras/MAPK信号通路中的重要成员，该通路与皮肤表皮异常分化及皮肤肿瘤形成密切相关。申请人前期研究发现RIPK4 (Receptor-interacting protein kinase 4) 能够促进皮肤表皮细胞分化，抑制皮肤鳞状细胞癌形成，并且 Raf1是皮肤鳞状细胞癌中RIPK4的结合配体。本项目拟利用前期研究成功构建的RIPK4条件性敲除小鼠，从细胞分化、增殖、凋亡三方面研究RIPK4抑制皮肤鳞状细胞癌形成的细胞学机制；从RIPK4结合Raf1的条件、方式、位点及结合形成的RIPK4/Raf1复合物抑癌作用研究RIPK4拮抗Raf1抑制皮肤鳞状细胞癌的分子机制。上述研究将有助于深入认识皮肤鳞状细胞癌发生的新型机制，发掘新的治疗靶点。

目前，皮肤鳞状细胞癌具体的发病原因和机制尚不清楚，早期诊治缺乏针对性。本项目前期分析RIPK4与皮肤表皮细胞分化，肿瘤形成相关通路网络中的作用及基于OncoLnc公共数据分析RIPK4与恶性肿瘤患者生存预后的相关性。结果显示，RIPK4表达与结肠腺癌、卵巢浆液性囊腺癌的预后负相关，但与肾乳头状细胞癌、肾透明细胞癌的预后正相关。此外，从RIPK4缺失对皮肤鳞状细胞癌细胞增殖，克隆形成，细胞周期及凋亡影响的角度出发，更精确阐述RIPK4抑制皮肤鳞状细胞癌形成的细胞学机制。RIPK4敲低后，A431细胞增殖、克隆形成、侵袭和增殖能力均显著增强，但细胞周期及凋亡无明显变化。通过构建可用荧光蛋白强度及比例预测皮肤表皮分化程度的慢病毒荧光报告载体，明确RIPK4与皮肤表皮分化程度及放射治疗敏感性的相关性。Ras/MAPK信号通路与皮肤表皮异常分化及肿皮肤肿瘤形成密切相关，本项目进一步研究RIPK4对于Raf/MEK/ERK信号通路的影响。最后对于恶性肿瘤上皮细胞RIPK4的表达与免疫治疗疗效相关性进行探索性研究。