USP35 promotes breast cancer progression by regulating PFK-1 ubiquitination to mediate glycolysis

Background: Ubiquitin‑specific protease 35 (USP35) was found to be involved in various tumor progression, but its role in breast cancer remains largely unknown. Methods: USP35 mRNA and protein expression in breast cancer tissues and cells were evaluated by qPCR and Western bolt (WB), respectively. Subsequently, flow cytometry and EDU labeling were used to evaluate breast cancer cell apoptosis and proliferation. Cellular glycolytic function was analyzed using the Seahorse assay and various kits. Furthermore, Co-immunoprecipitation (Co-IP) and immunoprecipitation (IP) assays were utilized to validate the deubiquitylation mechanism of USP35. Finally, a subcutaneous human xenograft tumor model was established in nude mice to verify the effect of USP35 in vivo. Results: By examining the clinical samples and cell lines, we found that USP35 expression was significantly upregulated in breast cancer. Further functional studies showed that knockdown USP35 expression inhibited cell proliferation and promoted apoptosis. In addition, knockdown of USP35 decreased PFK-1 expression and was associated with lower extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) compared with sh-Control. Co-IP assays identified phosphofructokinase1 (PFK-1) as a direct deubiquitiation target of USP35. Importantly, we demonstrated that PFK-1 is an essential mediator for USP35-induced cell proliferation and glycolysis in vitro and in vivo. Conclusion: This study identified that USP35 regulates proliferation and glycolysis of breast cancer cells by mediating the ubiquitination level of PFK-1. The USP35/PFK-1 axis offers novel insight for the treatment of breast cancer.