Paper Title
THE STUDY OF REGULATION OF PD-1/PD-L1 EXPRESSION IN BREAST CANCER CELLS

Abstract
Abstract - Recently, immunotherapy has achieved excellent therapeutic efficacy in a variety of tumors, including melanoma, non-small cell lung cancer, renal cell carcinoma, colorectal cancer, as well as breast cancer. Cancer cells expressing PD-L1 interacts with PD-1 expressed on tumor-specific T cells or other immune cells in the tumor microenvironment to achieve an adaptive immune mechanism to escape immune responses. In this regards, monoclonal antibodies specifically against programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) are considered as critical breakthroughs in cancer immunotherapy. Various pathways have been reported to regulate PD-1/PD-L1 expressions in cancer cells, such as PI3K/Akt pathway, MAPK pathway, JAK/STAT pathway, Wnt pathway, NF-kB pathways, and Hedgehog pathway. In addition, PD-1/PD-L1 protein stabilization or protein-protein interaction are possibly modulated by post-translational modifications. Our study shows that PD-1 and PD-L1 protein expression are enhanced mutually in a contact-dependent manner in U251 and THP-1-derived macrophages mixed-cell co-culture system. Whether the regulatory mediator(s) exert autocrine pathway in regulating PD-1 or PD-L1 expression and/or deubiquitination upon cell-cell contact will need further investigations.