LncRNA CCAT1 facilitates the progression of gastric cancer via PTBP1-mediated glycolysis enhancement

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.