Synergistic Effect of Epigenetic Modulator Decitabine and Metformin in the Battle Against Gastric Cancer: A Potential Therapeutic Strategy

The 5-year global survival rate of patients with gastric cancer (GC) is approximately 20%; however, 74% of these patients survived for up to 1 year with effective therapy. The anticancer effects of metformin, an antidiabetic agent, and 5-Aza-2′-deoxycytidine (5-AZA-CdR, decitabine), a DNA methyltransferase inhibitor that leads to malignant cell differentiation and apoptosis, have been investigated. In this study, we evaluated the synergistic effects of decitabine and metformin to achieve better GC treatment. MTT assay was used to assess the viability of MKN ₄₅ cells, and flow cytometry was employed to evaluate apoptosis induction using Annexin V and propidium iodide (PI) staining. The expression profiles of key proapoptotic genes were compared across five distinct cell groups. Protein-protein interaction (PPI) network construction and pathway enrichment analysis were used to gain new insights into biological pathways. MTT assays demonstrated that metformin and decitabine inhibited cell viability at IC ₅₀ values of 17.37 mM and 3.20 µM, respectively. A synergistic effect in promoting apoptosis compared to single treatments was shown by flow cytometry analysis and the Bliss synergy model (combination index (CI) < 1). All treatments, especially the combination of 5-AZA-CdR and metformin, led to a decrease in the number of cells in the S phase (down to 7.2%), while increasing the percentage of cells in the G2/M phase, indicating that normal cell cycle progression was disrupted and apoptosis was effectively induced. Metformin and decitabine did not affect target gene expression, except for the increased expression of CASP-1 (7.21 ± 0.48; p bon = 0.003) and CASP-3 (7.17 ± 0.19; p bon = 0.007) in response to decitabine exposure. However, the synergistic effect of decitabine and metformin significantly changed the expression of all target genes, downregulating BCL ₂ (0.56 ± 0.05; p bon = 0.0005) and significantly increasing the expression of BAX (8.08 ± 0.15; p bon < 0.0001), caspase-1 (8.47 ± 0.34; p bon < 0.0001), caspase-3 (9.45 ± 0.26; p bon < 0.0001), and ATG ₇ (1.97 ± 0.15; p bon = 0.001). The BAX/BCL ₂ gene expression ratio was significantly increased in the cells treated with metformin (7.18 ± 1.16, p bon = 0.018) and 5Aza + metformin (14.46 ± 1.46, p bon < 0.0001) compared with the control group. Bioinformatics analysis showed that why combining decitabine with metformin may be a game-changer in treatment. This study revealed a notable synergistic effect of the combination of decitabine and metformin in GC cell apoptosis triggering, which may inform future therapeutic strategies for GC management.