ENO1 Knockdown Impedes Tumour Progression and Promotes Oxidative Phosphorylation in Cutaneous Squamous Cell Carcinoma.

Cutaneous squamous cell carcinoma (cSCC) is a common skin malignancy characterized by aggressive growth and metabolic reprogramming. Alpha-enolase (ENO1), a key glycolytic enzyme that is frequently over-expressed in cancer, has not been thoroughly investigated in cSCC, particularly with regard to how it coordinates glycolysis and oxidative phosphorylation (OXPHOS). ENO1 expression was interrogated in Gene Expression Omnibus datasets and validated in cSCC patient specimens. ENO1 was silenced in cSCC cell lines, and the resulting effects on cell viability, migration, invasion, apoptosis, and reactive oxygen species (ROS) levels were quantified. The impact of ENO1 knockdown on tumour growth was assessed in a xenograft model. Metabolic flux was analysed with Seahorse XFe96 extracellular-flux assays. ENO1 was significantly elevated in cSCC relative to normal skin and correlated positively with proliferative and invasive markers, but negatively with apoptosis markers. ENO1 silencing curtailed cell viability, migration, and invasion, while inducing apoptosis. Additionally, tumour growth was significantly impaired in vivo. Seahorse analysis showed that ENO1 knockdown suppressed glycolysis and redirected metabolic flux toward OXPHOS. Consistent with this shift, intracellular ROS increased and partially suppressed cell viability by modulating the ROS-sensitive Akt/mTOR pathway. In conclusion, ENO1 knockdown compromises tumorigenicity and promotes OXPHOS. Combining ENO1 inhibition with oxidative-stress-enhancing treatments, such as chemotherapy or radiotherapy, may further enhance efficacy.