He Xiaobo, Wang Qiu-Xia, Wei Denghui, Lin Yujie, Zhang Xia, Wu Yuanzhong, Qian Xuexia, Lin Zhihao, Xiao Beibei, Wu Qinxue, Wang Zhen, Zhou Fengtao, Wei Zhihao, Wang Jingxuan, Gong Run, Zhang Ruhua, Zhang Qingling, Ding Ke, Gao Song, Kang Tiebang
Sun Yat-sen University Cancer Center, Guangdong Provincial Clinical Research Center for Cancer, State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, China.
Department of Pathology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong, China.
Cell Res. 2025 Apr 21. doi: 10.1038/s41422-025-01110-x.
Oncogenic mutations in EGFR often result in EGF-independent constitutive activation and aberrant trafficking and are associated with several human malignancies, including non-small cell lung cancer. A major consequence of EGFR mutations is the activation of the mechanistic target of rapamycin complex 1 (mTORC1), which requires EGFR kinase activity and downstream PI3K/AKT signaling, resulting in increased cell proliferation. However, recent studies have elucidated kinase-independent roles of EGFR in cell survival and cancer progression. Here, we report a cis mTORC1 activation function of EGFR that is independent of its kinase activity. Our results reveal that lysosomal localization of EGFR is critical to mTORC1 activation, where EGFR physically binds Rheb, acting as a guanine exchange factor (GEF) for Rheb, with its Glu804 serving as a potential glutamic finger. Genetic knock-in of EGFR-E804K in cells reduces the level of GTP-bound Rheb, and significantly suppresses mTORC1 activation, cell proliferation and tumor growth. Different tyrosine kinase inhibitors exhibit distinct effects on EGFR-induced mTORC1 activation, with afatinib, which additionally blocks EGFR's GEF activity, causing a much greater suppression of mTORC1 activation and cell growth, and erlotinib, which targets only kinase activity, resulting in only a slight decrease. Moreover, a novel small molecule, BIEGi-1, was designed to target both the Rheb-GEF and kinase activities of EGFR, and shows a strong inhibitory effect on the viability of cells harboring EGFR mutants. These findings unveil a fundamental event in cell growth and suggest a promising strategy against cancers with EGFR mutations.
表皮生长因子受体（EGFR）的致癌突变通常导致不依赖表皮生长因子（EGF）的组成性激活和异常转运，并与包括非小细胞肺癌在内的多种人类恶性肿瘤相关。EGFR突变的一个主要后果是雷帕霉素机制靶点复合物1（mTORC1）的激活，这需要EGFR激酶活性和下游磷脂酰肌醇-3激酶/蛋白激酶B（PI3K/AKT）信号传导，从而导致细胞增殖增加。然而，最近的研究阐明了EGFR在细胞存活和癌症进展中的非激酶依赖性作用。在此，我们报道了EGFR的一种顺式mTORC1激活功能，该功能独立于其激酶活性。我们的结果表明，EGFR的溶酶体定位对mTORC1激活至关重要，在那里EGFR与Rheb物理结合，作为Rheb的鸟嘌呤核苷酸交换因子（GEF），其谷氨酸804（Glu804）作为潜在的谷氨酸指。在细胞中基因敲入EGFR-E804K可降低结合GTP的Rheb水平，并显著抑制mTORC1激活、细胞增殖和肿瘤生长。不同的酪氨酸激酶抑制剂对EGFR诱导的mTORC1激活表现出不同的作用，阿法替尼除了阻断EGFR的GEF活性外，还对mTORC1激活和细胞生长产生更大的抑制作用，而仅靶向激酶活性的厄洛替尼只会导致轻微下降。此外，设计了一种新型小分子BIEGi-1，以靶向EGFR的Rheb-GEF和激酶活性，并对携带EGFR突变的细胞活力显示出强烈的抑制作用。这些发现揭示了细胞生长中的一个基本事件，并提出了一种针对EGFR突变癌症的有前景的策略。
