Oral cancer has traditionally been treated with surgery,
radiotherapy,
chemotherapy, or a combination of these
therapies. Although
cisplatin, a
chemotherapy drug, can effectively kill
oral cancer cells by forming
DNA adducts, its clinical use is limited due to adverse effects and chemo-resistance. Therefore, there is a need to develop new, targeted anticancer drugs to
complement chemotherapy, allowing for reduced
cisplatin doses and minimizing adverse effects. Recent studies have shown that 3,5-Bis (4-hydroxy-3-methoxybenzylidene)-N-methyl-4-piperidine (PAC), a new
curcumin analog, possesses anticancer properties and could be considered a complementary or alternative
therapy. In this study, we aimed to assess the potential complementary effects of PAC in combination with
cisplatin for treating
oral cancer. We conducted experiments using
oral cancer cell lines (Ca9-22) treated with different concentrations of
cisplatin (ranging from 0.1 μM to 1 μM), either alone or in conjunction with PAC (2.5 and 5 μM). Cell growth was measured using the MTT assay, while cell cytotoxicity was evaluated using an LDH assay.
Propidium iodide and
annexin V staining were employed to examine the impact on cell apoptosis. Flow cytometry was used to investigate the effects of the PAC/
cisplatin combination on
cancer cell autophagy, oxidative stress, and DNA damage. Additionally, a Western Blot analysis was performed to assess the influence of this combination on pro-carcinogenic
proteins involved in various signaling pathways. The results demonstrated that PAC enhanced the efficacy of
cisplatin in a dose-dependent manner, leading to a significant inhibition of
oral cancer cell proliferation. Importantly, treatment with PAC (5 μM) alongside different concentrations of
cisplatin reduced the IC50 of
cisplatin tenfold. Combining these two agents increased apoptosis by further inducing
caspase activity. In addition, the concomitant use of PAC and
cisplatin enhances
oral cancer cell autophagy, ROS, and
MitoSOX production. However, combined PAC with
cisplatin inhibits the mitochondrial membrane potential (ΔΨm), which is a marker for cell viability. Finally, this combination further enhances the inhibition of
oral cancer cell migration via the inhibition of epithelial-to-mesenchymal transition genes, such as
E-cadherin. We demonstrated that the combination of PAC and
cisplatin markedly enhanced
oral cancer cell death by inducing apoptosis, autophagy, and oxidative stress. The data presented indicate that PAC has the potential to serve as a powerful complementary agent to
cisplatin in the treatment of gingival
squamous cell carcinomas.