Abstract
Background:
T-cell exhaustion induced by the tumor microenvironment is an important factor in posing a major challenge to effective cancer immunotherapy. Immune checkpoint inhibitors aim to reverse T-cell exhaustion. However, the effectiveness of immune checkpoint inhibitors is often limited due to their off-target effects and single targets. Herein, we attempt to identify molecular targets that can regulate the expression of multiple immune checkpoints to reverse T-cell exhaustion.
Methods:
NSG mice with xenotransplantation of human bladder cancer cells were used to investigate the function of nuclear paraspeckle assembly transcript 1 (NEAT1) in T-cell exhaustion. Chromatin isolation by RNA purification, chromatin immunoprecipitation, and luciferase assays was employed to investigate the molecular mechanisms by which NEAT1 regulates expression of target genes.
Results:
NEAT1, a bladder cancer-related long non-coding RNA (lncRNA), promotes lactate production in tumor cells by binding to the lactate dehydrogenase A gene. This lactate production subsequently inhibits NEAT1 expression in CD8+T cells. Furthermore, NEAT1 in CD8+T cells plays a crucial role in modulating the immune response of CD8+T cells against tumor cells. Our findings indicate that NEAT1 regulates the expression of multiple immune checkpoint genes by directly binding to them and inhibiting transcription through the alteration of histone lactylation near transcriptional start sites, which affects RNA polymerase II recruitment.
Conclusions:
lncRNA NEAT1 serves as a modulator of the antitumor response of CD8+T cells in the bladder tumor microenvironment and may represent a therapeutic target for reversing T-cell exhaustion.