Background: 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. Methods: 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. Results: 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. Conclusions: 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.

Helicobacter pylori (H. pylori) is known to be a major pathogen causing gastric diseases through its direct localization in gastric epithelium cells. H. pylori releases outer membrane vesicles (OMVs) throughout the growth process. The content, function, and mechanism of H. pylori OMVs in gastric epithelial cells remain unclear. In this study, we extracted and characterized H. pylori OMVs of two strains (standard strain NCTC11637 and clinical strain Hp-400) and analyzed the specific content by proteomic technology. We identified more than 400 proteins in H. pylori OMVs. In addition, we investigated the impact of H. pylori OMVs on cellular functions by detecting proteomic changes in GES1 cells. GES1 cells cocultured with increasing concentrations of H. pylori OMVs were subjected to quantitative proteomic analyses using label-free methods for relative quantitation. The results showed that a total of 4261 proteins were verified, 153 of which were significantly altered in abundance when cocultured with NCTC11637 OMVs, and a total of 4234 proteins in Hp-400 OMVs, 390 of which were significantly altered. Gene ontology analysis and Kyoto encyclopedia of genes and genomes pathway mapping identified significantly altered inflammatory and cancer signaling pathways, including metabolic pathways and the PI3K-Akt signaling pathway. Furthermore, we explored the proteomic changes in GES1 cells induced by H. pylori. Bioinformatics analysis showed that changes in multiple pathways coincided with OMV-mediated proteomic changes. Based on these results, H. pylori induced pathogenicity in epithelial cells at least partially by secreting OMVs that mediated dramatic and specific proteomic changes in host cells. Data are available via ProteomeXchange with identifiers PXD025216, PXD025259, and PXD025281.

Circulating tumor cells (CTCs) are promising biomarkers for clinical application. Cancer screening with Low-Dose Computed Tomography (LDCT) and CTC detections in pulmonary nodule patients has never been reported. The aim of this study was to explore the effectiveness of the combined methods to screen lung cancer. Out of 8313 volunteers screened by LDCT, 32 ground-glass nodules (GGNs) patients and 19 healthy volunteers were randomly selected. Meanwhile, 15 lung cancer patients also enrolled. CellCollector, a new CTC capturing device, was applied for CTCs detection. In GGNs group, five CTC positive patients with six CTCs were identified, 15.6% were positive (range, 1–2). In lung cancer group, 73.3% of the analyzed CellCollector cells were positive (range, 1–7) and no “CTC-like” events were detected in healthy group. All CTCs detected from GGNs group were isolated from the CellCollector functional domain and determined by whole genomic amplification for next-generation sequencing(NGS) analysis. NGS data showed that three cancer-related genes contained mutations in five CTC positive patients, including KIT, SMARCB1 and TP53 genes. In four patients, 16 mutation genes existed. Therefore, LDCT combined with CTC analysis by an in vivo device in high-risk pulmonary nodule patients was a promising way to screen early stage lung cancer.