Chemotherapy-induced cellular senescence is characterized by aberrant lipid regulation and lipid peroxidation

ABSTRACT: As normal cells approach their proliferative limit, they arrest to undergo replicative senescence, displaying large cell size, flat morphology and activation of senescence-associated beta-galactosidase (SA-b-Gal). A subset of normal or tumor cells exposed in vitro or in vivo to chemotherapy agents such as etoposide perform a related response with a similar cellular phenotype dubbed therapy-induced senescence (TIS). High cellular heterogeneity in samples including TIS cells can impede confident determination of senescence-specific factors, frustrating discovery of markers and targets for functional analysis. As a TIS study model, we treated murine melanoma cells with the chemotherapeutic etoposide, applied a live-cell fluorescent SA-b-Gal senescence assay, and utilized fluorescence-activated cell sorting (FACS) to enrich TIS cells. Enriched senescent cell samples were subjected to mass spectrometry and label-free quantitative proteomics analysis, alongside proliferating and quiescent cell samples. Systems biology analysis revealed that senescent cells overexpress proteins and pathways regulating glycolipid processing, lipid metabolism, and lipid peroxidation. Senescence-associated activation of numerous glycosidases was observed, along with elevated cell surface expression of several major lipid regulatory proteins. Senescent cells were found to contain abundant lipid droplets and to import various types of extracellular lipids in correlation with extent of SA-b-Gal expression, and tumor cells were observed to spontaneously senesce in the presence of excess ceramide or triglycerides. Redox-induced lipid peroxidation, resulting in accumulation of cellular reactive aldehydes and consequent expression of aldehyde detoxification enzymes, was observed to be a key feature of TIS induced by three DNA-damaging chemotherapeutics.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Cell Culture

SUBMITTER: Donald Wolfgeher  

LAB HEAD: Stephen J Kron

PROVIDER: PXD006216 | Pride | 2017-11-06

REPOSITORIES: Pride