Cancer cells rely on metabolic reprogramming to sustain the prodigious energetic requirements for rapid growth and proliferation. Glutamine metabolism is frequently dysregulated in cancers and is being exploited as a potential therapeutic target. Using CRISPR/Cas9 interference (CRISPRi) screening, we identified TARBP1 (TAR (HIV-1) RNA Binding Protein 1) as a critical regulator involved in glutamine reliance of cancer cell. Consistent with this discovery, TARBP1 amplification and overexpression are frequently observed in various cancers. Knockout of TARBP1 significantly suppresses cell proliferation, colony formation and xenograft tumor growth. Mechanistically, TARBP1 selectively methylates and stabilizes a small subset of tRNAs, which promotes efficient protein synthesis of glutamine transporter-ASCT2 (also known as SLC1A5) and glutamine import to fuel the growth of cancer cell. Moreover, we found that the gene expression of TARBP1 and ASCT2 are upregulated in combination in clinical cohorts and their upregulation is associated with unfavorable prognosis of HCC (hepatocellular carcinoma). Taken together, this study reveals the unexpected role of TARBP1 in coordinating the tRNA availability and glutamine uptake during HCC progression and provides a potential target for tumor therapy.

癌细胞依靠代谢重编程来维持快速生长和增殖的巨大能量需求。谷氨酰胺代谢在癌症中经常失调，并被用作潜在的治疗靶点。使用 CRISPR/Cas9 干扰 (CRISPRi) 筛选，我们确定 TARBP1 (TAR (HIV-1) RNA 结合蛋白 1) 是参与癌细胞谷氨酰胺依赖的关键调节因子。与这一发现一致的是，在各种癌症中经常观察到TARBP1扩增和过度表达。 TARBP1的敲除显着抑制细胞增殖、集落形成和异种移植肿瘤生长。从机制上讲，TARBP1 选择性甲基化并稳定一小部分 tRNA，从而促进谷氨酰胺转运蛋白 ASCT2（也称为 SLC1A5）的有效蛋白质合成和谷氨酰胺输入以促进癌细胞的生长。此外，我们发现TARBP1和ASCT2的基因表达在临床队列中联合上调，并且它们的上调与HCC（肝细胞癌）的不良预后相关。总而言之，这项研究揭示了 TARBP1 在 HCC 进展过程中协调 tRNA 可用性和谷氨酰胺摄取方面的意想不到的作用，并为肿瘤治疗提供了潜在的靶点。