Targeting the Warburg effect in cancer cells through ENO1 knockdown rescues oxidative phosphorylation and induces growth arrest

Abstract

In the last 5 years, novel knowledge on tumor metabolism has been revealed with the identification of critical factors that fuel tumors. Alpha-enolase (ENO1) is commonly over-expressed in tumors and is a clinically relevant candidate molecular target for immunotherapy. Here, we silenced ENO1 in human cancer cell lines and evaluated its impact through proteomic, biochemical and functional approaches. ENO1 silencing increased reactive oxygen species that were mainly generated through the sorbitol and NADPH oxidase pathways, as well as autophagy and catabolic pathway adaptations, which together affect cancer cell growth and induce senescence. These findings represent the first comprehensive metabolic analysis following ENO1 silencing. Inhibition of ENO1, either alone, or in combination with other pathways which were perturbed by ENO1 silencing, opens novel avenues for future therapeutic approaches.

Alpha-enolase (ENO1) controls alpha v/beta 3 integrin expression and regulates pancreatic cancer adhesion, invasion, and metastasis

“…2e) of shENO1 cells, in line with the modification of the expression of proteins involved in the remodeling of the cytoskeleton and adhesion (Ref. [19] and Fig. 1).…”

“…Previous LC-MS/MS semi-quantitative proteomic analysis using LTQ-Orbitrap on shENO1 CFPAC-1 cells showed significant alterations in the expression of 17 proteins involved in cell adhesion and cytoskeleton organization [19]. Four of these proteins [actin related protein 2/3 complex subunit 4 isoform a (ARPC4), capping protein actin filament muscle Z-line alpha 2 (CAPZA2), secreted phosphoprotein 1 isoform a (SPP1 also named Osteopontin), and breast cancer anti-estrogen resistance 1 (BCAR1 also named p130cas)] were upregulated, and 13 [AHNAK nucleoprotein isoform 1 (AHNAK), anterior gradient protein 2 (AGR2), catenin, delta 1 isoform 1ABC (CTNND1), hypothetical protein LOC64855 isoform 2 (MINERVA), Galectin 3 (LGALS3), catenin alpha 1 (CTNNA1), integrin alpha v isoform 1 precursor (ITGAV), Galectin 4 (LGALS4), Golgi apparatus protein 1 isoform 1 (GLG1), mucin 5AC (MUC5AC), serine or cysteine proteinase inhibitor clade B ovalbumin member 5 (SERPINb5), PDZ and LIM domain 1 (PDLIM1), and cysteine-rich protein 1 intestinal (CRIP1)] were downregulated [19]. …”

“…[19] and Fig. 1), and we therefore investigated the impact of ENO1 silencing on the actin cytoskeleton organization and morphology, by confocal analysis.…”

“…Images were taken at microscope with ×10 objective. The SA-β-galactosidase activity was analyzed as previously described [19]. …”

“…Many metabolic enzymes, including ENO1, are known to interact with cytoskeletal proteins (e.g., F-actin, tubulin), and these associations provide ATP to promote the migration of tumor cells [16, 17]. Although the roles of ENO1 as a glycolytic enzyme [18, 19] and as a plasminogen receptor [12, 20] have been well characterized, its role in the regulation of cytoskeleton reorganization, particularly in PDA cells, has not been fully clarified. Integrins regulate adhesion-dependent growth and invasion of tumor cells and the integrin alpha v/beta 3 has been reported as a mediator of anchorage independence [21], and its expression has been associated with an aggressive form of disease in different human tumors including PDA [22–27].…”