Morin reverses P‐glycoprotein‐mediated multidrug‐resistance in KBChR‐8‐5 cancer cell lines.

Multidrug resistance (MDR) during clinical chemotherapy for cancer has been considered a major obstacle to treatment efficacy. The involvement of adenosine triphosphate‐binding cassette (ABC) transporters in the MDR mechanism significantly reduces the efficacy of chemotherapeutics. This study investigates the potential of morin, a dietary bioflavonoid, to overcome colchicine resistance in KBChR‐8‐5 MDR cells. The P‐gp inhibitory activity by morin was measured by calcein‐AM drug efflux assay. Western blot analysis was employed to evaluate P‐gp messenger RNA and protein expressions following morin treatment. Flow cytometry analysis and acridine orange/ethidium bromide fluorescence staining were utilised to investigate the induction of apoptosis and cell cycle arrest upon treatment with morin and paclitaxel in combination. Additionally, polymerase chain reaction (PCR) array analysis was conducted to study the gene expression profiles related to MDR, apoptosis and cell cycle arrest during treatment with morin, paclitaxel or their combination. Morin exhibited a strong binding interaction with human P‐gp. This was corroborated by drug efflux assays, which showed a reduction in P‐gp efflux function with increasing morin concentration. Furthermore, morin and paclitaxel combination potentiated the induction of apoptosis and G2/M phase cell cycle arrest. Morin treatment significantly downregulated the gene expression of ABCB1 and P‐gp membrane expressions in MDR cells. Additionally, PCR array gene expression analysis revealed that the combination treatment with morin and paclitaxel upregulated proapoptotic and cell cycle arrest genes while downregulating ABCB1 gene and antiapoptotic genes. Thus, morin effectively reversed paclitaxel resistance in KBChR‐8‐5 drug‐resistant cancer cells and concluded that morin resensitized the paclitaxel resistance in KBChR8‐5 drug‐resistant cancer cells. Significance Statement: Multidrug resistance (MDR) is a critical challenge in cancer treatment, primarily during chemotherapy, often mediated by P‐glycoprotein (P‐gp), a key adenosine triphosphate‐binding cassette transporter. Despite extensive efforts to develop P‐gp inhibitors, many have failed due to adverse effects. Recent focus has shifted to phytochemicals due to their potential for fewer side effects. Morin, a dietary phytochemical, has emerged as a promising candidate for reversing MDR by reducing P‐gp drug efflux function and membrane expression. Its efficacy suggests it could serve as a lead compound for developing novel P‐gp inhibitors with improved safety profiles, offering hope for more effective cancer treatment strategies. [ABSTRACT FROM AUTHOR]