PD‐L2 Expression in Breast Cancer Promotes Tumor Development and Progression

Abstract

Background. This work focused on investigating the role of programmed death ligand 2 (PD‐L2) in the progression of breast cancer by utilizing breast cancer specimens and cells. Materials and Methods. The serum levels of soluble PD‐L2 (sPD‐L2) in breast cancer patients and healthy individuals were analyzed by means of the enzyme‐linked immunosorbent assay, and the PD‐L2 levels within 416 resected breast cancer specimens were assessed through immunohistochemistry. Concurrently, in vitro cell experiments and in vivo animal experiments were carried out to analyze the relationship between PD‐L2 and the invasion and migration of breast cancer. Results. The concentration of sPD‐L2 in breast cancer patients significantly increased compared to that in the control groups. Additionally, breast cancer patients with high concentrations of sPD‐L2 had higher Ki67 values (≥30%) and tumor grades. PD‐L2 was expressed in 79.09% of the cancer samples, which exhibited a positive correlation with the progesterone receptor (PR) and the human epidermal growth factor receptor 2 (HER2). Furthermore, we discovered that knockdown of PD‐L2 inhibited the migratory and invasive abilities of both MCF‐7 and MDA‐MB231 cells. Conclusion. Our findings demonstrated that knockdown of PD‐L2 suppressed tumor growth, providing novel insights into important biological functions.