Effects of caffeic acid phenethyl ester on cell death and survival pathways in human osteosarcoma cells

Osteosarcoma is the most common primary malignant bone tumour, accounting for approximately 20% of all primary bone tumours and about 5% of paediatric cancers. Due to therapeutic resistance and poor prognosis, novel treatment strategies are actively being explored, including natural compounds with antitumor potential. Caffeic acid phenethyl ester (CAPE), has attracted attention because of its antioxidant, anti-inflammatory, and antiproliferative properties. The present study investigated the effects of CAPE on cell death and survival pathways in human osteosarcoma cell lines (MG-63 and Saos-2) using MTT and RealTime-Glo viability assays, gene expression analysis by RT-qPCR, zymography, and qualitative hematoxylin-eosin staining and immunofluorescence. CAPE significantly reduced tumour cell viability, with IC50 values of 11.5 and 14.2 µM for MG-63 and Saos-2 cells, respectively, compared with 91.8 µM in normal cells. These effects were corroborated by morphological analyses, which revealed reduced cell density and marked structural alterations. CAPE positively modulated the expression of caspase pathway genes, BAX, and TIMP-1, while downregulating MMP-2 expression, thereby favouring a pro-apoptotic environment. In addition, zymography demonstrated reduced MMP-9 activity, a key enzyme involved in tumour invasion. Collectively, these findings highlight the promising antitumor potential of CAPE and support further investigations into its therapeutic applicability in osteosarcoma.