Structural Dynamics of OATP1A2 in Mediating Paclitaxel Transport Mechanism in Breast Cancer

Breast cancer remains a significant global health challenge, with drug resistance and poor bioavailability of chemotherapeutic agents like paclitaxel (PTX) presenting obstacles to effective treatment. This study investigates the potential role of the Solute Carrier Organic Anion Transporter Polypeptide 1A2 (OATP1A2) in PTX transport using computational approaches. We employed computational modeling, molecular docking, and molecular dynamics (MD) simulations to elucidate the structural dynamics of OATP1A2 and its interaction with PTX. The OATP1A2 structure was modeled using Phyre2, validated, and refined. Molecular docking revealed significant PTX interactions within the predicted binding site, with a binding affinity of -10.4 kcal/mol and initial hydrogen bonding with Arg⁶⁵⁶ and Gly⁵⁶⁰ and hydrophobic interaction with atGlu⁶⁶, Phe⁶⁵, Asn⁴¹, Ala²⁰³, Ile²⁰⁴, Phe³²⁹, Phe³³², Ile³³⁶, Pro²⁰⁷, Ser³³⁷, Asn³³⁴. Contrary to our initial hypothesis of inward drug movement, MD simulation over 500 ns revealed an unexpected outward movement of PTX. The ligand shifted approximately 5.4 Å towards the extracellular side from its initial binding position. This observation suggests a more complex transport mechanism than initially anticipated. The protein-ligand complex exhibited stability throughout the simulation, with notable conformational changes. Our findings highlight the complex nature of OATP1A2-mediated transport and its potential limitations for PTX delivery. These results accentuate the complexity of transporter-mediated drug delivery and may inform future strategies for improving chemotherapeutic efficacy in breast cancer treatment.