Antiproliferative and synergistic effects of cannabinoids in combination with cisplatin on cervical cancer cell lines.

This study employed a mixed-methods in vitro experimental design, integrating quantitative and qualitative approaches to investigate the anticancer effects of Δ⁹-tetrahydrocannabinol (THC) and cannabidiol (CBD), alone and in combination with cisplatin, in cervical cancer cell lines (HeLa and SiHa) and a non-tumourigenic breast epithelial cell line (MCF-12A). Quantitative analyses included sulforhodamine B (SRB) assays to assess cytotoxicity and determine IC₅₀ values, Bliss Independence modelling using SynergyFinder to evaluate drug interactions, flow cytometry to analyse cell cycle progression and apoptosis (Annexin V/PI), confocal microscopy to assess autophagic activity via LC3B expression, and quantitative polymerase chain reaction (qPCR) to evaluate DNA damage and repair gene expression (XRCC1 and RAD51). Qualitative assessment of treatment-induced morphological changes was conducted using light and fluorescence microscopy, with image analysis performed using ImageJ. Statistical analyses were carried out using GraphPad Prism. The findings demonstrated that cannabinoids significantly reduced cervical cancer cell viability in a time-, dose-, and serum-dependent manner, with reduced serum conditions enhancing cytotoxic potency. The combination of THC, CBD, and cisplatin exhibited synergistic interactions in cervical cancer cells while sparing non-tumourigenic cells, indicating therapeutic selectivity. Mechanistically, the combination treatment induced G₂/M cell cycle arrest, increased apoptosis and autophagic activity, and downregulated DNA repair pathways, collectively enhancing cisplatin efficacy. These results support the potential of cannabinoids as selective co-therapeutic agents in cervical cancer treatment and highlight the importance of optimized in vitro conditions when evaluating lipophilic compounds.