Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
Department of Pathology & Guangdong Province Key Laboratory of Molecular Tumor Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China.
EMBO J. 2022 Aug 1;41(15):e110218. doi: 10.15252/embj.2021110218. Epub 2022 Jul 1.
Carnitine metabolism is thought to be negatively correlated with the progression of hepatocellular carcinoma (HCC) and the specific molecular mechanism is yet to be fully elucidated. Here, we report that little characterized cysteine-rich protein 1 (CRIP1) is upregulated in HCC and associated with poor prognosis. Moreover, CRIP1 promoted HCC cancer stem-like properties by downregulating carnitine energy metabolism. Mechanistically, CRIP1 interacted with BBOX1 and the E3 ligase STUB1, promoting BBOX1 ubiquitination and proteasomal degradation, and leading to the downregulation of carnitine. BBOX1 ubiquitination at lysine 240 is required for CRIP1-mediated control of carnitine metabolism and cancer stem-like properties. Further, our data showed that acetylcarnitine downregulation in CRIP1-overexpressing cells decreased beta-catenin acetylation and promoted nuclear accumulation of beta-catenin, thus facilitating cancer stem-like properties. Clinically, patients with higher CRIP1 protein levels had lower BBOX1 levels but higher nuclear beta-catenin levels in HCC tissues. Together, our findings identify CRIP1 as novel upstream control factor for carnitine metabolism and cancer stem-like properties, suggesting targeting of the CRIP1/BBOX1/β-catenin axis as a promising strategy for HCC treatment.
肉碱代谢被认为与肝细胞癌(HCC)的进展呈负相关,但其具体的分子机制尚未完全阐明。在这里,我们报告了一个特征不明显的富含半胱氨酸的蛋白 1(CRIP1)在 HCC 中上调,并与预后不良相关。此外,CRIP1 通过下调肉碱能量代谢促进 HCC 癌干样特性。在机制上,CRIP1 与 BBOX1 和 E3 连接酶 STUB1 相互作用,促进 BBOX1 的泛素化和蛋白酶体降解,导致肉碱的下调。CRIP1 介导的 BBOX1 赖氨酸 240 泛素化对于控制肉碱代谢和癌干样特性是必需的。此外,我们的数据表明,CRIP1 过表达细胞中乙酰肉碱的下调降低了β-连环蛋白的乙酰化水平,并促进了β-连环蛋白的核积累,从而促进了癌干样特性。临床上,HCC 组织中 CRIP1 蛋白水平较高的患者 BBOX1 水平较低,但核β-连环蛋白水平较高。总之,我们的研究结果表明,CRIP1 是肉碱代谢和癌干样特性的新型上游调控因子,提示靶向 CRIP1/BBOX1/β-连环蛋白轴可能成为 HCC 治疗的一种有前途的策略。