Alpha-eleostearic acid induces autophagy-dependent cell death through targeting AKT/mTOR and ERK1/2 signal together with the generation of reactive oxygen species.
Alpha-eleostearic acid (alpha-ESA, 9Z11E13E-18:3), a linolenic acid isomer with a conjugated triene system, is a natural and biologically-active compound that has been shown to possess potent anti-tumor properties. Herein, we demonstrate alpha-ESA induced apoptosis and autophagy with reactive oxygen species (ROS) generation in HeLa cells. Treatment with alpha-ESA caused inhibition of phosphorylated (p)AKT and elongated the sub G1 phase in the cell cycle, indicating induction of apoptosis. Autophagy was also induced by alpha-ESA treatment, causing low pAKT and pP70S6K activities, increasing pERK1/2 and leading to a higher conversion rate of LC3 I to LC3 II compared to that of the control. The autophagy was further confirmed by fluorescence microscopy and flow cytometry through monodansylcadavarine (MDC) staining. It appears that the role of autophagy is a protective mechanism against cell death in alpha-ESA-treated HeLa cells. Subsequently, we found that treating HeLa cells with alpha-ESA induced the generation of reactive oxygen species (ROS). The phosphorylation of P70S6K, downstream of mTOR signaling, and AKT were further reduced by pretreatment with N-acetyl-l-cysteine (NAC), an ROS scavenger, whereas the phosphorylation of ERK1/2 and the conversion of LC3 I to LC3 II were further enhanced. As a result, the blocking of the action of ROS promoted alpha-ESA-induced apoptosis and autophagy. Taken together, our results indicate that the generation of ROS by alpha-ESA treatment impedes the progress of apoptosis and excessive autophagy formation which takes part in cell death, thus impeding death promotion.
Eom
Jung-Min
JM
Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea.
Seo
Min-Ji
MJ
Baek
Ji-Young
JY
Chu
Hyuk
H
Han
Seung Hyun
SH
Min
Tae Sun
TS
Cho
Chong-su
CS
Yun
Cheol-Heui
CH
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D001343:Autophagy; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008042:Linolenic Acids / Q000494:pharmacology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases
D000970:Antineoplastic Agents; D047908:Intracellular Signaling Peptides and Proteins; D008042:Linolenic Acids; D017382:Reactive Oxygen Species; C004934:eleostearic acid; C546842:MTOR protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3