PD-1/PD-L1 pathway: current researches in cancer

Abstract

Cancer immunotherapy has been accompanied by promising results over the past few years. Programmed Cell Death Protein 1 (PD-1) plays a vital role in inhibiting immune responses and promoting self-tolerance through modulating the activity of T-cells, activating apoptosis of antigen-specific T cells and inhibiting apoptosis of regulatory T cells. Programmed Cell Death Ligand 1 (PD-L1) is a trans-membrane protein that is considered to be a co-inhibitory factor of the immune response, it can combine with PD-1 to reduce the proliferation of PD-1 positive cells, inhibit their cytokine secretion and induce apoptosis. PD-L1 also plays an important role in various malignancies where it can attenuate the host immune response to tumor cells. Based on these perspectives, PD-1/PD-L1 axis is responsible for cancer immune escape and makes a huge effect on cancer therapy. This review is aimed to summarize the role of PD-1 and PD-L1 in cancer, looking forward to improve the therapy of cancer.

Keywords: PD-1; PD-L1; cancer.

Figure 1

The PD-1/PD-L1 axis inhibits T cell activation, proliferation, and survival and cytotoxic secretion within cancer cell.

Figure 2

Various pathways regulation of PD-1/PD-L1 expression. PI3K/AKT pathway, MAPK pathway, JAK/STAT pathway, WNT pathway, NF-κB pathway and Hedgehog (Hh) pathway promote the expression of PD-1/PD-L1 axis.

Figure 3

Inhibitors of PD-1/PD-L1 in cancers.