Curcumin and doxorubicin encapsulated in biocompatible clay-based nanomaterial: A strategy to overcome multidrug resistance.

Multidrug resistance (MDR) due to the overexpression of the P-glycoprotein (P-gp) efflux pump remains a significant challenge in cancer therapy, also in breast cancer. Traditional pharmacological approaches have focused on using inhibitors to modulate P-gp expression and function. Curcumin, a polyphenol derived from Curcuma longa L., is one of the most extensively studied natural compounds with the potential as an effective P-gp inhibitor. Despite its promising attributes, the clinical application of P-gp inhibitors is complicated by P-gp's presence in healthy cells, such as those in the intestinal barrier and blood-brain barrier, which can lead to increased toxicity. To address these challenges, we developed a novel multifunctional nanomaterial by covalently bonding halloysite nanotubes (HNTs) with hectorite (Ht) and loading it with curcumin and doxorubicin. The efficacy of the co-delivery of curcumin and doxorubicin by HNTs-Ht nanomaterial was evaluated by cytotoxicity assays on MCF-7R cells, both in two-dimensional (2D) and in three-dimensional (3D) models. The obtained data show that curcumin causes increased doxorubicin accumulation by acting as a substrate for P-gp transport and as a stimulator of the adenosine triphosphate (ATP)-dependent drug efflux transporter on a doxorubicin-resistant breast cancer cell line. The results suggest that the HNTs-Ht nanomaterial could provide a promising approach to improve chemotherapy effectiveness by overcoming MDR and enhancing treatment outcomes.