Exploration of the anticancer properties of Caffeic Acid in malignant mesothelioma cells

Malignant Pleural Mesothelioma (MPM) is the most prevalent type of Mesothelioma and currently has no effective treatment options. This underscores the urgent need to explore new therapeutic agents and innovative strategies. Phenolic acids are significant natural compounds recognised for their effectiveness in treating various diseases, including cancer. This study evaluates the anti-carcinogenic properties of Cinnamic acid (CINN) and its derivative Caffeic acid (CA) in both MPM and non-cancerous mesothelial cells. Results show that CA exhibited greater efficiency than CINN in reducing cancer cell survival. This enhanced efficacy is primarily attributed to CA's higher selectivity index and its ability to inhibit proliferation at lower concentrations. Consequently, further analysis was conducted using CA. The subsequent findings revealed that CA suppressed proliferative markers, Ki67 and PCNA, inhibited colony formation and wound healing in MM cells. Experiments also exposed that it suppresses the phosphorylation of ERK1/2 and AKT proteins in a concentration-dependent manner, while the phosphorylation of STAT3 remains unaffected. The pattern of protein phosphorylation and expression suppression by CA in 3D cells resembles that in 2D cells, although it occurred at higher concentrations. Additionally, CA significantly enhanced the expression of p53-regulated proteins p21 and p27, resulting in G2/M arrest in both SPC111 and SPC212 cell lines. Moreover, elevated concentrations of CA were associated with an increased number of dead cells, as demonstrated by DAPI/PI and AO/EtBr fluorescence staining. The increased Bax/Bcl-2 protein ratio, and BH3-only proteins (Bik and PUMA) and the cleavage of caspase-3 indicated that CA induces mitochondrial apoptosis. Our research with MM cells and three-dimensional micro-tumours suggests that CA may be a promising alternative for future MM therapies. However, it is vital to conduct high-throughput in vivo studies to elucidate further the potential importance of CA in treating this devastating disease.