p21 Prevents the Exhaustion of Cluster of Differentiation 4-Positive T Cells Within the Antitumor Immune Response Against Colorectal Cancer.

Abstract

BACKGROUND & AIMS:

T cells are crucial for the antitumor response against colorectal cancer (CRC). T-cell reactivity to CRC is nevertheless limited by T-cell exhaustion. However, molecular mechanisms regulating T-cell exhaustion are only poorly understood.

METHODS:

We investigated the functional role of cyclin-dependent kinase 1a (Cdkn1a or p21) in cluster of differentiation (CD) 4+ T cells using murine CRC models. Furthermore, we evaluated the expression of p21 in patients with stage I to IV CRC. In vitro coculture models were used to understand the effector function of p21-deficient CD4+ T cells.

RESULTS:

We observed that the activation of cell cycle regulator p21 is crucial for CD4+ T-cell cytotoxic function and that p21 deficiency in type 1 helper T cells (Th1) leads to increased tumor growth in murine CRC. Similarly, low p21 expression in CD4+ T cells infiltrated into tumors of CRC patients is associated with reduced cancer-related survival. In mouse models of CRC, p21-deficient Th1 cells show signs of exhaustion, where an accumulation of effector/effector memory T cells and CD27/CD28 loss are predominant. Immune reconstitution of tumor-bearing Rag1-/- mice using ex vivo-treated p21-deficient T cells with palbociclib, an inhibitor of cyclin-dependent kinase 4/6, restored cytotoxic function and prevented exhaustion of p21-deficient CD4+ T cells as a possible concept for future immunotherapy of human disease.

CONCLUSIONS:

Our data reveal the importance of p21 in controlling the cell cycle and preventing exhaustion of Th1 cells. Furthermore, we unveil the therapeutic potential of cyclin-dependent kinase inhibitors such as palbociclib to reduce T-cell exhaustion for future treatment of patients with colorectal cancer.

• Authors: Oana-Maria Thoma, Elisabeth Naschberger, Markéta Kubánková, Imen Larafa, Viktoria Kramer, Bianca Menchicchi, Susanne Merkel, Nathalie Britzen-Laurent, André Jefremow, Robert Grützmann, Kristina Koop, Clemens Neufert, Raja Atreya, Jochen Guck, Michael Stürzl, Markus F Neurath, Maximilian J Waldner
• Journal: Gastroenterology (Gastroenterology) (Sep 19 2023) ISSN: 1528-0012 [Electronic] United States
• PMID: 37734420 (Publication Type: Journal Article)
• Copyright: Copyright © 2023 AGA Institute. Published by Elsevier Inc. All rights reserved.