Knockdown of ENO1 promotes autophagy dependent-ferroptosis and suppresses glycolysis in breast cancer cells via the regulation of CST1

Autophagy-dependent ferroptosis and glycolysis play a significant role in tumor development. α-Enolase (ENO1), a glycolytic enzyme, has been demonstrated to function as a crucial modulator in breast cancer (BC). However, the specific mechanism by which ENO1 influences the ferroptosis and glycolysis of BC remains unclear. qRT-PCR, along with western blot analysis was applied to investigate ENO1 and cystatin SN (CST1) expression in BC cells. Glycolysis level was measured by extracellular acidification rate (ECAR), lactate production, glucose consumption, and western blot analysis. Ferroptosis was evaluated by iron and lipid peroxidation assay, DCFH-DA staining, and western blot analysis. Immunofluorescence, together with western blot analysis was adopted for assessing cell autophagy and mTOR signaling pathway. Cell apoptosis and Ki67 level were measured by TUNEL and immunohistochemistry, respectively. ENO1 had abundant existence in BC cell lines. ENO1 silencing inhibited glycolysis but promoted ferroptosis and autophagy. In addition, autophagy inhibitor 3-MA reversed the impacts of ENO1 silencing on glycolysis and ferroptosis. Meanwhile, mTOR activator MHY1485 demonstrated opposing effects on autophagy. Moreover, CST1 could be extensively found in BC cell lines, and its overexpression reversed the effects of ENO1 silencing on glycolysis and ferroptosis. In vivo experiments illustrated that ENO1 deletion suppressed BC tumor growth, increased the apoptosis rate, restrained cell proliferation, and glycolysis, but promoted ferroptosis and autophagy, as well as reducing CST1 and mTOR signaling. To sum up, ENO1 silencing mediated a utophagy-dependent ferroptosis and glycolysis in BC cells by regulating CST1.