NR2F2 controls malignant squamous cell carcinoma state by promoting stemness and invasion and repressing differentiation III

The non-genetic mechanisms required to sustain malignant tumor state are poorly understood. During the transition from benign tumors to malignant carcinoma, tumor cells need to repress differentiation and acquire invasive features. Using transcriptional profiling of cancer stem cells (CSC) from benign tumors and malignant skin squamous cell carcinoma (SCC), we identified the nuclear receptor NR2F2 as uniquely expressed in malignant SCC. Using genetic gain- and loss-of-function in vivo, we show that NR2F2 is essential for promoting the malignant tumor state by controlling tumor stemness and maintenance in mouse and human SCC. We demonstrate that NR2F2 promotes tumor cell proliferation, epithelial-mesenchymal transition (EMT) and invasive features, while repressing tumor differentiation and immune cell infiltration by regulating a common transcriptional program in mouse and human SCCs. Altogether, we identify NR2F2 as a key regulator of malignant CSC functions that promotes tumor renewal and restricts differentiation to sustain malignant tumor state. FACS isolated Epcam+tumor cells from Ctrl vs NR2F2 overexpression (GOF) papillomas and Ctrl (Cre-) vs K5CreER;NR2F2fl/fl skin SCC

维持恶性肿瘤状态所需的非遗传机制目前仍未得到充分阐明。在良性肿瘤向恶性癌转变的过程中，肿瘤细胞需要抑制分化并获得侵袭性表型。本研究通过对良性肿瘤及恶性皮肤鳞状细胞癌（skin squamous cell carcinoma, SCC）中的癌症干细胞（cancer stem cell, CSC）开展转录谱分析，鉴定出核受体NR2F2在恶性SCC中特异性表达。通过体内遗传学功能获得与功能缺失实验，我们证实NR2F2可通过调控小鼠及人类SCC的肿瘤干细胞干性与维持能力，在促进恶性肿瘤状态的过程中发挥必需作用。本研究进一步证实，NR2F2可通过调控小鼠与人类SCC共有的转录程序，促进肿瘤细胞增殖、上皮间质转化（epithelial-mesenchymal transition, EMT）及侵袭性表型，同时抑制肿瘤分化与免疫细胞浸润。综上，本研究鉴定出NR2F2是恶性癌症干细胞功能的关键调控因子，可通过促进肿瘤自我更新、抑制分化以维持恶性肿瘤状态。本研究的实验样本包括：通过荧光激活细胞分选术（fluorescence-activated cell sorting, FACS）分离得到的对照组与NR2F2过表达（功能获得，GOF）乳头状瘤中的Epcam+肿瘤细胞，以及对照组（Cre-）与K5CreER;NR2F2fl/fl皮肤鳞状细胞癌样本。