Autophagy inhibition enhanced 5-FU-induced cell death in human gastric carcinoma BGC-823 cells

Abstract

The exact molecular mechanism of 5-fluorouracil (5-FU) in human gastric cancer cells remains to be elucidated. Cultured BGC-823 human gastric carcinoma and AGS cell lines were treated with 5-FU. Autophagosome formation was investigated through multiple approaches, including the quantification of green fluorescent protein-microtubule-Associated protein 1A/1B-light chain 3 (LC3) puncta, LC3 conversion and electron microscopy observations. Additionally, autophagy was inhibited using 3-methyladenine (3-MA) and beclin-1 ablation, to determine its role in 5-FU-mediated cell death. In addition, the present study assessed alterations in sirtuin expression following 5-FU treatment with reverse transcription-quantitative polymerase chain reaction. 5-FU treatment induced apoptosis and inhibited proliferation in BGC-823 and AGS gastric cancer cells. It is of note that the 5-FU treatment only promoted autophagy in BGC-823 cells. Additionally, inhibition of autophagy by either 3-MA or beclin-1 ablation increased 5-FU-induced cell death in BGC-823 cells. The present study quantified changes in sirtuin (SIRT1, SIRT3, SIRT5, and SIRT6) expression following 5-FU treatment and using a specific inhibitor, sirtinol, the present study investigated their involvement in 5-FU-mediated autophagy. Autophagy inhibition through manipulation of sirtuin proteins may increase the therapeutic efficacy of the 5-FU chemotherapeutic drug against gastric carcinoma.