Autophagic death induced by thermo-chemotherapy in gastric cancer cells results from the reactive oxygen species pathway

Abstract

Gastric cancer is the third leading type of cancer and has the third leading cancer‑associated mortality in China. The mechanism of thermo‑chemotherapy in gastric cancer cells remains to be elucidated. The present study aimed to investigate the role of autophagic cell death in the thermo‑chemotherapy of gastric cancer. The current study included four groups: An empty control group, a hyperthermia group, a chemotherapy (oxaliplatin) group, and a thermo‑chemotherapy group. Cell viability was analyzed by the MTS assay. Production of intracellular reactive oxygen species (ROS) was quantified by flow cytometry. Autophagy‑associated proteins, Beclin 1, microtubule‑associated protein 1A/1B‑light chain (LC3B) and mammalian target of rapamycin (mTOR), were determined by western blot analysis. The results indicated that thermo‑chemotherapy markedly increased intracellular ROS production, and decreased mitochondrial membrane potential. The transmission electron microscopy results indicated that thermo‑chemotherapy induced production of autophagic bodies. In addition, thermo‑chemotherapy‑induced cell damage at the cellular and animal levels indicated a notable increase in the expression of the autophagy‑associated genes, LC3B and Beclin 1. A negative correlation between mTOR expression and autophagy was also identified, which demonstrates that thermo‑chemotherapy induces autophagic cell death by activating the autophagy‑associated signaling pathways. The results of the present study demonstrated that the ROS level is important in autophagic death of the gastric carcinoma cells, and the increased ROS level, induced by thermo‑chemotherapy treatment, induced autophagy in gastric carcinoma cells.

Combined effects of hyperthermia and chemotherapy on the regulate autophagy of oral squamous cell carcinoma cells under a hypoxic microenvironment

“…It has been reported that ROS acted on the complex formed by Beclin-1 and anti-apoptotic Bcl-2 homologs such as Bcl-2 and Bcl-xL. Moreover, this complex repressed the pro-autophagic activity of Beclin-1 and ROS could induce the dissociation of autophagy molecules Beclin 1 and Bcl-2, thus activating the Beclin1-induced autophagy pathway, increasing the expression of LC3-II, thereby initiating autophagy-associated pathways [ 49 , 50 ]. ROS is also reported to upregulate the activity of HIF1-α which facilitates the activation of the HIF1-α/BNIP3/Beclin1 autophagy signaling pathway.…”

Hyperthermia combined chemotherapy regulates energy metabolism of cancer cells under hypoxic microenvironment

“…It has been reported that ROS acted on the complex formed by Beclin-1 and anti-apoptotic Bcl-2 homologs such as Bcl-2 and Bcl-xL. Moreover, this complex repressed the pro-autophagic activity of Beclin-1 and ROS could induce the dissociation of autophagy molecules Beclin 1 and Bcl-2, thus activating the Beclin1-induced autophagy pathway, increasing the expression of LC3-II, thereby initiating autophagy-associated pathways [48,49]. In addition, ROS is also reported to upregulate the activity of HIF1-α, and some scholars have also shown that the expression and activity of HIF-1a is not only induced in response to limited oxygen supply, but it is also regulated through related signaling pathways, including the extracellular signal-regulated kinase (ERK) [50] and the protein kinase B (AKT) [51] pathway, and hyperthermia promoted the expression of HIF-1α by activating phosphatidylinositol 3-kinase(PI3K)…”