Anti-cancer Effects of 1,4-Dialkoxynaphthalene-Imidazolium Salt Derivatives through ERK5 kinase activity inhibition

ERK5 has emerged as a promising therapeutic target in cancer treatment due to its pivotal role in regulating tumor cell proliferation and survival. In this study, we synthesized novel derivatives of 1,4-dialkoxynaphthalene-2-acyl or 2-alkyl-imidazolium salt (NAIMS), assessed their binding affinity with the ERK5 protein through molecular modeling, and evaluated their anti-cancer activity through the ERK5 kinase assay. Based on the MTT assay and qRT-PCR analysis of 21 synthesized NAIMS, the IC₅₀ values for 4c, 4e, and 4k (8.5 μM, 6.8 μM, and 8.9 μM, respectively) and the inhibition rate of the expression of PCNA for 4c, 4e, and 4k (50%, 61.1%, and 70.2% of 5 μM respectively) were chosen for comprehensive biological research. Further analyses including DAPI staining, and flow cytometry confirmed that 4c, 4e, and 4k induced late-stage apoptosis, and triggered cell cycle arrest in the G2/M phase of HeLa cells. Moreover, molecular modeling analysis showed that 4e exhibited strong and stable molecular interactions at the ERK5 ATP-binding site. Our results strongly suggest that NAIMS compounds, especially 4e, could serve as novel inhibitors of ERK5, presenting promising lead compound to develop for cancer treatment.