Optimal timing of autophagy occurrence induced by earle's balanced salts solution in DLD-1, HCT-116, A2780, CHO, Hep G2 and SMMC7721 cancer cell lines

Autophagy has emerged as a key effector in tumorgenesis, but its precise function remains elusive. Autophagy flux is too low to be detected in normal culture conditions. Earle's balanced salts solution (EBSS) is often used to induce autophage with two distinct advantages compared with other inducers: one is only needed to considerate the induction time, rather than the drug concentration; the other is that it exerts only starvation pressure by specifically simulating amino acids deprivation to cells without other undistinguishable cytotoxicity. Given the tolerance threshold of outside stimulus differs in various types of tumor cells, in this study we carried out the autophage induction experiments with several time points in DLD-1 and HCT-116 colon cancer cell lines, A2780 and CHO ovarian cancer cell lines, Hep G2 and SMMC7721 hepatocellular carcinoma cell lines. Our western-blotting and Immunofluorescence staining results demonstrated that EBSS can efficiently induce autophagy in the assayed cells, precisely with 2 hours treatment in DLD-1, HCT-116, Hep G2 and CHO cells, 4 hours in A2780 and 8 hours in SMMC7721 cells, respectively. Our results provide a reference for autophagy induction with EBSS in cancer cells, and would be useful to shorten the time-consuming optimizing process.