Abstract: ob＜x＞jective To investigate the role and mechanism of CPEB3 in the glycolytic me＜x＞tabolism of breast cancer cells. Methods The ex＜x＞pression of CPEB3 was detected by RT-qPCR and Western blot. Cell proliferation abilit y of MCF-7 was assessed by CCK-8 assay. Annexin V-FITC/PI kit was used to assess cell apoptosis. Transwell assay was performed to measure cell migration rate, and colorimetric assay kits were used to determine glucose concentration and lactate content in the cell culture medium. Results CPEB3 was significantly downregulated in breast cancer cells compared to normal breast epithelial cells (P<0.05). Overex＜x＞pression of CPEB3 markedly inhibited proliferation, migration and glycolysis of MCF-7 cells ( P<0.05), while promoting their apoptosis (P<0.05). Moreover, CPEB3 overex＜x＞pression obviously reduced the ex＜x＞pression of IL-6R and p-STAT3 (P<0.05), while STAT3 overex＜x＞pression significantly reversed the inhibitory effect of CPEB3 on glycolysis in MCF-7 cells (P<0.05). Conclusion CPEB3 inhibits glycolysis in breast cancer cells by regulating IL-6R/STAT3 pathway