Department of Molecular Medicine and Medical Biotechnology, University Federico II, Naples, Italy.
Cancer Research Center of Marseille (CRCM), CNRS, Aix Marseille Univ, INSERM, Institut Paoli-Calmettes, Marseille, France.
Commun Biol. 2024 Feb 20;7(1):208. doi: 10.1038/s42003-024-05823-4.
Clear cell renal cell carcinoma (ccRCC) is the most common kidney cancer in the adult population. Late diagnosis, resistance to therapeutics and recurrence of metastatic lesions account for the highest mortality rate among kidney cancer patients. Identifying novel biomarkers for early cancer detection and elucidating the mechanisms underlying ccRCC will provide clues to treat this aggressive malignant tumor. Here, we report that the ubiquitin ligase praja2 forms a complex with-and ubiquitylates the AP2 adapter complex, contributing to receptor endocytosis and clearance. In human RCC tissues and cells, downregulation of praja2 by oncogenic miRNAs (oncomiRs) and the proteasome markedly impairs endocytosis and clearance of the epidermal growth factor receptor (EGFR), and amplifies downstream mitogenic and proliferative signaling. Restoring praja2 levels in RCC cells downregulates EGFR, rewires cancer cell metabolism and ultimately inhibits tumor cell growth and metastasis. Accordingly, genetic ablation of praja2 in mice upregulates RTKs (i.e. EGFR and VEGFR) and induces epithelial and vascular alterations in the kidney tissue.In summary, our findings identify a regulatory loop between oncomiRs and the ubiquitin proteasome system that finely controls RTKs endocytosis and clearance, positively impacting mitogenic signaling and kidney cancer growth.
透明细胞肾细胞癌(ccRCC)是成人中最常见的肾癌。诊断较晚、对治疗的耐药性和转移性病变的复发是导致肾癌患者死亡率最高的原因。鉴定新的生物标志物用于早期癌症检测,并阐明 ccRCC 的发生机制,将为治疗这种侵袭性恶性肿瘤提供线索。在这里,我们报告泛素连接酶 praja2 与 AP2 衔接复合物形成复合物,并泛素化该复合物,有助于受体内化和清除。在人 RCC 组织和细胞中,致癌 miRNA(oncomiRs)和蛋白酶体下调 praja2 会显著损害表皮生长因子受体(EGFR)的内化和清除,并放大下游有丝分裂和增殖信号。在 RCC 细胞中恢复 praja2 水平会下调 EGFR,重新调整癌细胞代谢,最终抑制肿瘤细胞生长和转移。因此,在小鼠中基因敲除 praja2 会上调 RTKs(即 EGFR 和 VEGFR),并诱导肾脏组织中的上皮和血管改变。
总之,我们的研究结果确定了致癌 miRNA 和泛素蛋白酶体系统之间的调控环,该调控环精细地控制 RTKs 的内化和清除,对有丝分裂信号和肾癌生长有积极影响。