Autophagy and Apoptosis Cross-Talk in Response to Epigallocatechin Gallate in NALM-6 Cell Line

Chemotherapy, the primary treatment for acute lymphoblastic leukemia (ALL), often yields inadequate responses. Epigallocatechin gallate (EGCG) has been shown to significantly affect tumor cells through various mechanisms, including cell cycle arrest, apoptosis, and autophagy.

The objective of this study is to explore the impact of EGCG on autophagy, apoptosis, and the interplay between them in NALM-6, a pre-B-ALL cell line.

NALM-6 cells were subjected to various concentrations of EGCG for 24 and 48 hours. Additionally, NH4Cl 10 mM was used as an autophagy inhibitor to examine this mechanism. The EGCG effect on cell viability and apoptosis was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), trypan blue exclusion assay, and flow cytometry. Moreover, western blot analysis and real-time PCR were performed to investigate autophagy.

Our findings demonstrated that EGCG significantly affected cell proliferation and viability. It reduced cell viability by 55.2 ± 8.4% (P < 0.0001) while inducing apoptosis by 51 ± 1.9% (P = 0.006). Furthermore, in the presence of NH4Cl, EGCG led to a 3.9 ± 1.8-fold increase in LC3 protein level (P = 0.001). It also resulted in an approximately 1.34 ± 0.34-fold enhancement in DRAM1 mRNA expression levels (P = 0.013), while reducing of LC3B by 33.3 ± 30.5% (P = 0.008), P62/SQSTM1 by 46.5 ± 28.3% (P < 0.001), and Atg2B by 45.5 ± 16.3% (P < 0.001). However, the inhibition of autophagy did not alter the apoptosis rate in either untreated or EGCG-treated cells.

Overall, our findings suggest that EGCG can trigger apoptosis and autophagy in NALM-6 cell line. However, blockage of autophagy does not appear to impact apoptosis in this cell line.