Comparison of two-dimensional and three-dimensional triple negative breast cancer cell culture models on treatment response

Triple negative breast cancer (TNBC) has a dismal prognosis and few available treatments, making it a major clinical challenge. This study assesses the effectiveness of cannabidiol (CBD), which has pro-apoptotic and anti-proliferative qualities, and olaparib (OLAP), a PARP inhibitor that targets DNA repair, as single and combination therapies in TNBC and estrogen receptor positive (ER+) breast cancer cell lines. In two-dimensional (2D) and three- dimensional (3D) culture systems, analyses were conducted on MDA-MB-231 (TNBC), HCC-70 (TNBC), and MCF-7 (ER+) cell lines. The results demonstrated that in 3D culture models, increased efficacy was attained with lower doses, and that OLAP and CBD caused synergistic cytotoxic effects, particularly in TNBC cells. In MDA-MB-231 cells with G2/M phase arrest, increased apoptosis was seen, as demonstrated by flow cytometry and caspase 3/7 tests. DNA damage response and cell cycle-related genes (ATM, ATR, BRCA1/2, RAD51, and CDK1/2/4/6) were down-regulated by the combined treatment, according to gene expression analysis. Specifically, 3D spheroid models under metabolic and hypoxic stress demonstrated heightened drug sensitivity. These results imply that 3D culture methods provide more physiologic and sensitive models for evaluating medication efficacy, and that OLAP and CBD together offer a possible therapeutic approach for aggressive breast cancer subtypes.