Tumor cell-intrinsic PD-1 receptor is a tumor suppressor and mediates resistance to PD-1 blockade therapy

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• Immune checkpoint molecules like programmed cell death 1 (PD-1) on immune cells facilitate tumor immune escape.
• Antibodies targeting PD-1 enhance T cell antitumor activity in certain cancers.
• The role of PD-1 within tumor cells themselves is largely unexplored.

Purpose of the Study:

• To investigate the expression and function of PD-1 and its ligand PD-1 ligand 1 (PD-L1) in tumor cells.
• To determine the impact of PD-1/PD-L1 on tumor cell proliferation, growth, and response to immunotherapy.
• To elucidate the downstream signaling pathways involved in PD-1/PD-L1 mediated tumor suppression.

Main Methods:

• Analysis of PD-1 expression across various tumor cell types.
• In vitro and in vivo experiments involving gene silencing and overexpression of PD-1 and PD-L1.
• Assessment of cell proliferation, colony formation, and tumor growth.
• Treatment with blocking antibodies against PD-1 and PD-L1.
• Investigation of downstream signaling pathways, including AKT and ERK1/2.

Main Results:

• PD-1 is expressed in a wide range of tumor cells.
• Silencing PD-1 or PD-L1 enhanced tumor cell proliferation and growth in vitro and in vivo.
• Overexpression of PD-1 or PD-L1 inhibited tumor cell proliferation and colony formation.
• Blocking antibodies targeting PD-1/PD-L1 promoted tumor growth.
• PD-1/PD-L1 signaling activates AKT and ERK1/2 pathways, contributing to tumor cell growth inhibition.

Conclusions:

• PD-1 and PD-L1 function as tumor suppressors, inhibiting tumor cell proliferation and growth.
• The PD-1/PD-L1 axis plays a critical role in regulating tumor cell behavior.
• PD-1/PD-L1 may serve as a predictive biomarker for anti-PD-1/PD-L1 cancer immunotherapy response.