Research Center, the Fourth Hospital of Hebei Medical University, Jiankang Road 12, Shijiazhuang, 050011, Hebei, China.
Key Laboratory of Tumor Gene Diagnosis, Prevention and Therapy; Clinical Oncology Research Center, Shijiazhuang, 050001, Hebei, China.
J Exp Clin Cancer Res. 2023 Sep 23;42(1):246. doi: 10.1186/s13046-023-02827-6.
Gastric cancer (GC) is one of the most prevalent malignant tumors of the digestive system. As a hallmark of cancer, energy-related metabolic reprogramming is manipulated by multiple factors, including long non-coding RNAs (lncRNAs). Notably, lncRNA CCAT1 has been identified as a crucial regulator in tumor progression. Nevertheless, the precise molecular mechanisms underlying the involvement of CCAT1 in metabolic reprogramming of GC remain unclear.
Gain- and loss-of-function experiments were performed to evaluate the roles of CCAT1 in tumorigenesis and glycolysis of GC. Bioinformatics analyses and mechanistic experiments, such as mass spectrometry (MS), RNA-pulldown, and RNA immunoprecipitation (RIP), were employed to reveal the potential interacting protein of CCAT1 and elucidate the regulatory mechanism of CCAT1 in GC glycolysis. Moreover, the nude mice xenograft assay was used to evaluate the effect of CCAT1 on GC cells in vivo.
In this study, we identified that CCAT1 expression was significantly elevated in the tissues and plasma exosomes of GC patients, as well as GC cell lines. Functional experiments showed that the knockdown of CCAT1 resulted in a substantial decrease in the proliferation, migration and invasion of GC cells both in vitro and in vivo through decreasing the expression of glycolytic enzymes and glycolytic rate. Conversely, overexpression of CCAT1 exhibited contrasting effects. Mechanistically, CCAT1 interacted with PTBP1 and effectively maintained its stability by inhibiting the ubiquitin-mediated degradation process. As a critical splicing factor, PTBP1 facilitated the transition from PKM1 to PKM2, thereby augmenting the glycolytic activity of GC cells and ultimately fostering the progression of GC.
Our findings demonstrate that CCAT1 plays a significant role in promoting the proliferation, migration, and invasion of GC cells through the PTBP1/PKM2/glycolysis pathway, thus suggesting CCAT1's potential as a biomarker and therapeutic target for GC.
胃癌（GC）是消化系统最常见的恶性肿瘤之一。作为癌症的一个标志，能量相关的代谢重编程是由多种因素操纵的，包括长非编码 RNA（lncRNA）。值得注意的是，lncRNA CCAT1 已被确定为肿瘤进展的关键调节因子。然而，CCAT1 参与 GC 代谢重编程的确切分子机制尚不清楚。
通过 gain- 和 loss-of-function 实验来评估 CCAT1 在 GC 发生和糖酵解中的作用。采用生物信息学分析和机制实验，如质谱（MS）、RNA 下拉和 RNA 免疫沉淀（RIP），来揭示 CCAT1 的潜在互作蛋白，并阐明 CCAT1 在 GC 糖酵解中的调控机制。此外，还使用裸鼠异种移植实验来评估 CCAT1 对 GC 细胞在体内的影响。
在这项研究中，我们发现 CCAT1 的表达在 GC 患者的组织和血浆外泌体以及 GC 细胞系中显著升高。功能实验表明，通过降低糖酵解酶的表达和降低糖酵解速率，CCAT1 的敲低导致 GC 细胞在体外和体内的增殖、迁移和侵袭能力显著下降。相反，CCAT1 的过表达则表现出相反的效果。机制上，CCAT1 与 PTBP1 相互作用，并通过抑制泛素介导的降解过程有效地维持其稳定性。作为一个关键的剪接因子，PTBP1 促进了 PKM1 向 PKM2 的转变，从而增强了 GC 细胞的糖酵解活性，最终促进了 GC 的进展。
我们的研究结果表明，CCAT1 通过 PTBP1/PKM2/糖酵解途径在促进 GC 细胞的增殖、迁移和侵袭中发挥重要作用，提示 CCAT1 作为 GC 的潜在生物标志物和治疗靶点的可能性。
