Study On The Relationship Between Autophagy And Viability Decrease Of Hela Cells Induced By Spermidine

Spermidine, a polyamine widely distributed in organisms, plays an important role in many biological processes such as cell proliferation, organism aging, etc.. Recent years, autophagy induced by spermidine has become a well focused study area. Previous studies have shown that exogenous spermidine can induce autophagy and inhibit cell proliferation, but few reports are concern about whether spermidine could inhibit viability of cancer cells. There are also no studies about the relationship between spermidine-induced autophagy and the reduction of cancer cell viability. The present research aimed to explore the effect of spermidine-induced autophagy on cancer cell viability, as well as the regulation between spermidine-induced autophagy and intracellular ROS. In addition, the role of mitochondria in spermidine-induced autophagy and reduction of viability in cancer cells was also investigated.This study selected Hela cells as experimental material, spermidine as a drug. Viability of Hela cells treated with spermidine or spermidine combined with autophagy inhibitor3-Methyladenine (3-MA) was measured using MTT assay. The formation of autophagysomes or autolysosomes induced by spermidine in cells was observed by transmission electron microscopy. The expression of LC3, the classical indicator of autophagy, was detected by Western Blot. Intracellular ROS content and mitochondrial membrane potential was determined by flow cytometry.Through the above research, we draw the following experimental results. Exposure to0.1mM,0.5mM and1.0mM spermidine for8h significantly inhibited Hela cell vitality (p<0.05).0.5mM spermidine decreased cell viability to65.45%compared with control group. Autophagosomes and autolysosomes induced by0.5mM spermidine for8h can be observed through transmission electron microscope. In addition, the ratio of LC3-II/LC3-I (autophagy marker protein) in0.5mM spermidine group was1.83fold higher than that of control (p<0.05). Cell viability was increased by9.75%(p<0.05) when Hela cells were exposed to0.5mM spermidine combined with5.0mM3-MA for8h. Moreover, intracellular ROS level was significantly reduced by14.18%(p<0.05) and the mitochondrial membrane potential was respectively declined to62.59%and61.90%when Hela cells were treated with0.5mM and1.0mM spermidine for8h. However, once autophagy was inhibited, the content of ROS was prominently rescued by about10%(p<0.05). In summary, our study proved spermidine-induced autophagic death was one of the reasons to reduce Hela cell viability. Autophagy induced by spermindine could regulate ROS partly. The sharp decline of mitochondrial membrane potential caused by spermidine might mediate the induction of autophagy and reduction of cell viability.