Neuroblastoma is the most common extracranial tumor of young children, and the five-year overall survival of children with high-risk disease is less than 50%. Overexpression of multidrug resistance protein 1 (MRP1), a plasma membrane ATP-binding cassette (ABC) transporter, is associated with high-risk neuroblastoma. MRP1 transports multiple neuroblastoma chemotherapeutic agents out of the cell in a glutathione (GSH)-dependent manner. Other MRP1 substrates are transported in a GSH-independent manner, and certain compounds stimulate MRP1-mediated GSH efflux without being transported themselves. The mechanisms of GSH-dependent and GSH-independent MRP1 substrate transport ? as well MRP1-mediated GSH efflux ? are still not well understood.
Specific Aim 1 of this proposal seeks to determine the structural basis of GSH-dependent vs. GSH-independent substrate transport by MRP1 using cryo-electron microscopy coupled with biophysical, biochemical, and cell-based assays for MRP1 function.
Specific Aim 2 of this proposal seeks to determine the structural basis of the activation and inhibition of GSH efflux by ligands that regulate MRP1 activity. The successful completion of these aims will fill a gap in the research literature by determining the structural basis for MRP1 substrate poly-specificity, particularly with respect to chemotherapeutic agents used in the treatment of neuroblastoma, and will provide a basis for future therapeutic intervention. The proposed research strategy will be completed under the mentorship of Dr. Jue Chen in the Laboratory of Membrane Biology and Biophysics at The Rockefeller University in New York City. The accompanying fellowship training plan will be completed through the Tri-Institutional MD-PhD Program of Weill Cornell Medicine, The Rockefeller University, and Memorial Sloan Kettering Cancer Center. The exceptional clinical and scientific resources of these environments will facilitate the successful completion of both research and training components. The biochemical, biophysical, and structural biology equipment and expertise available at The Rockefeller University is unparalleled, and trainees are also encouraged to collaborate with other scientists and institutions in New York City?s rich structural biology research network. The Tri-Institutional MD-PhD Program offers a diversity of clinical, research, and extracurricular opportunities for trainees to develop the analytical, technical, communication, and mentoring skills necessary to become an independent physician-scientist. Trainees are encouraged to continuously develop their clinical and scientific skills throughout both medical and graduate phases of the MD-PhD curriculum. This curriculum is supervised by a supportive administration that provides ample guidance for trainees to pursue productive careers promoting the health of the American public.
Neuroblastoma is the most common extracranial solid tumor of childhood, and despite significant advances in the diagnosis and treatment of this disease, the prognosis for many patients remains poor. Overexpression of multidrug resistance protein 1 (MRP1) is strongly associated with neuroblastoma drug resistance and reduced patient survival. This proposal seeks to identify the structural basis by which MRP1 promotes neuroblastoma drug resistance, and completion of the proposed work will lay a foundation for future therapeutic development.
