Cigarette Smoke Extract induces Alpha-Enolase by inhibiting Prolyl-Hydroxylases in Cervical Cancer Cells. A comparative study of Reference cigarettes and E-cigarettes

Abstract

Cigarette Smoke (CS) is a major contributor to the development of a large number of fatal and debilitating disorders. Proteomic analysis was used as an investigative tool to systematically explore proteomic changes that contribute to alterations in the cellular milieu leading to progression of cancer upon CS exposure. In this study, we utilized Two-Dimensional Gel Electrophoresis (2-DE) and Mass Spectrometry (MS) technologies to explore protein changes in cervical cancer cells (HeLa) in response to cigarette smoke extract (CSE) exposure. Among the individual proteins resolved using 2DE, about 50 protein spots were analysed by MALDI-TOF/TOF in the first attempt. Proteins related to tumor microenvironment, chronic obstructive pulmonary disease and metastasis induction among others were identified. Of these, alpha-enolase, a multi-functional, yet predominantly a glycolytic enzyme that facilitates aerobic glycolysis through a process known as Warburg effect in cancers, was a prominent protein detected with significant change. Although this protein is known to be induced in cancers, it was not known to be altered by cigarette smoke exposure in cervical cancers. Mechanism-wise CSE induced and stabilized HIF-1a by inhibiting HIF-PH (prolyl-hydroxylases) and thereby, inducing alpha-enolase production in cervical cancer cells. The precise molecular mechanisms underlying the effects of CS in cervical disease are largely unknown. Further investigation on CSE treatment under non-hypoxia conditions in vitro and in vivo along with proteomic approach may potentially lead to new therapeutic approaches to smoking induced advancement of cervical cancer. The evidence warrants further investigation to indicate that Enolases play an important role in CS-induced gene expression and could be a potential therapeutic target to prevent cancer progression and metastasis.