OBJECTIVE To discuss the clinical value of RCBTB1 in the diagnosis and prognosis of gastric cancer (GC), and to study the mechanism of Yiqi Huayu Jiedu Formula (YHJF) underlying suppressing the liver metastasis induced by tumor-associated fibroblasts (CAFs-exo) secreted exosomes.

METHODS Bioinformatics combined with immunohistochemistry were used to verify the expression of RCBTB1 in GC tissues and its significance in diagnosis and prognosis. CAFs-exo was isolated and extracted by ultrafast centrifugal method, and identified by transmission electron microscopy, Western blot and NTA. The invasion and migration abilities of cells were detected by wound-healing and Transwell assays. The liver metastasis model of mice bearing GC was established, intervened with YHJF, and detected for the number of liver metastases. Hematoxylin-eosin staining was used to detect the infiltration of GC cells in the liver. The expression of related molecules was detected by Western blot. The exosome uptake of GC cells was detected by immunofluorescence. In vivo imaging was performed to observe the distribution of exosomes in the liver of mice with GC liver metastasis.

RESULTS The expression of RCBTB1 was increased in GC tissues (P < 0.001), and it had high diagnostic and predictive value (AUC=0.857). The related differentially expressed genes of RCBTB1 mainly enriched in biological behaviors such as extracellular matrix regulation, invasion and metastasis, and cell adhesion, as well as the Wnt/β-catenin signaling pathway. The expression level of RCBTB1 in stage T4 GC was significantly higher than that in stage T1, T2 and T3 (P < 0.01). Patients with high expression of RCBTB1 in stage T2 and T3 had a better clinical prognosis (P < 0.05), while those with high expression of RCBTB1 in stage T4 had a poor prognosis (P < 0.05). YHJF could significantly inhibit CAFs-exo induced invasion and migration of GC cells (P < 0.05) and the formation of liver metastases in mice with GC, up-regulate the expression of RCBTB1 and E-cadherin (P < 0.001), and down-regulate the expression of β-catenin and Snail (P < 0.001). Meanwhile, YHJF could reduce the uptake ability of exosomes of GC cells and inhibit the accumulation of exosomes in the liver of mice with GC liver metastasis.

CONCLUSION RCBTB1 is differentially expressed in GC at different stages and plays an important role in the clinical diagnosis and prognosis prediction of GC. YHJF can prohibit liver metastasis of GC by blocking CAFs-exo transmission and reversing RCBTB1-mediated epithelial mesenchymal transformation.