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

Michela Capello,Moitza Principe,Cecilia Roux,Michelle Samuel Chattaragada,Francesco Novelli,Sammy Ferri-Borgogno,Weidong Zhou,Chiara Riganti,Emanuel F Petricoin,Paola Cappello

doi:10.18632/oncotarget.6798

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.

Highlights

In most solid tumors, the Warburg effect, known as aerobic glycolysis, causes an increase in total glycolysis both in hypoxic conditions and in the presence of normal oxygen levels [1, 2]
Proteins from CFPAC-1 parental cells, cells infected with a scrambled shRNA and short hairpin RNA targeting ENO1 3′UTR (shENO1) cells were digested using trypsin, and the extracted peptides were identified by liquid chromatography coupled nanospray tandem mass spectrometry (LC-MS/MS) using LTQ-Orbitrap (Supplementary Table S1)
Cancer cells show increased aerobic glycolysis and enhanced lactate production compared to healthy cells, a phenomenon known as the Warburg effect [2]

Summary

Introduction

The Warburg effect, known as aerobic glycolysis, causes an increase in total glycolysis both in hypoxic conditions and in the presence of normal oxygen levels [1, 2]. To some extent, aerobic glycolysis may give cancer cells an advantage in competing with normal tissues for nutrients [3]. Accumulating evidence shows that the reprogramming of tumor metabolism is controlled by various oncogenic signals [4], such as RAS, AKT, MYC, PI3K, mTOR, together with tumor suppressors, including TP53 and PTEN, which alter metabolism and allow cancer cells to survive and proliferate in the hypoxic and nutrient-deprived tumor microenvironment. MBP-1 lacks the first 96 residues of ENO1 and localizes in the nucleus, where it binds to the c-myc P2 promoter and acts as a transcription repressor [8]. ENO1 is upregulated at the mRNA and/or protein level in several tumors including breast, lung, prostate and pancreas and is expressed on the cell surface of several tumors, where it acts as a plasminogen receptor and contributes to cell invasion, metastasis and inflammatory responses [9,10,11,12,13]

Methods

Results

Conclusion