Combining 5-ALA-PDT with berbamine as an in vitro multimodal therapy approach against bladder cancer cells

Abstract Bladder cancer is a common urogenital malignancy that remains difficult to treat, particularly due to therapeutic resistance, such as resistance to cisplatin, in which cancer stem cells (CSCs) play a central role. This study investigates the combination of 5-aminolevulinic acid-mediated photodynamic therapy (5-ALA-PDT) and berbamine as a potential multimodal treatment strategy using the bladder cancer cell lines RT112 and J82, their cisplatin-resistant variants, and generated CSC-like cells. Berbamine is a natural plant compound and was confirmed in this study to have anticancer properties by inhibiting cell migration and invasion, and by inducing apoptosis. This study also showed that berbamine enhances the accumulation of protoporphyrin IX (PpIX), the photosensitizer induced by 5-ALA. 5-ALA-PDT destroys cancer cells by stimulating PpIX via 635 nm red laser light to produce reactive oxygen species (ROS). This was found to happen in all tested cell lines, whereas berbamine could modulate the cell destruction in a concentration-dependent manner and was influenced by the specific biological characteristics of the tested cell variants. CSCs showed the strongest response to the combination therapy approach, suggesting that they may represent more vulnerable cell variants to the tested treatment. Cisplatin-resistant cell lines could also be treated successfully with 5-ALA-PDT, whereas berbamine could enhance its efficacy in the cisplatin-resistant J82 LTT. These findings suggest that the combination treatment of 5-ALA-PDT and berbamine may serve as a promising approach to overcome therapeutic resistance in bladder cancer, particularly in cisplatin-resistant and CSC-enriched tumour types.