DNA methylation of immune checkpoints in the peripheral blood of breast and colorectal cancer patients

Abstract

Aberrant expression of immune checkpoints (ICs) in cancer creates an immunosuppressive microenvironment, which supports immune evasion of tumor cells. We have recently reported that epigenetic modifications are critical for ICs expression in the tumor microenvironment (TME) of primary breast cancer (PBC) and colorectal cancer (CRC). Herein, we investigated transcriptomic expression of ICs (PD-1, CTLA-4, LAG-3, TIM-3, TIGIT) and PD-L1 in peripheral blood of PBC and CRC patients, compared to healthy donors (HD). We found that expressions of TIM-3, TIGIT, PD-L1 were significantly upregulated, while LAG-3 expression was downregulated in peripheral blood of PBC and CRC patients. Demethylation enzymes TET2 and TET3 were also upregulated. In addition, promoter DNA methylation status of PD-1 was significantly hypermethylated, while PD-L1 was hypomethylated in PBC and CRC patients. Furthermore, TIGIT was significantly hypomethylated only in CRC patients. Remarkably, promoter methylation status of LAG-3, TIGIT and PD-L1 was in concordance with transcriptomic expression in CRC: the more the hypomethylation, the higher the expression. In comparison, we found that CTLA-4, TIM-3, TIGIT and PD-L1 in PBC, and CTLA-4 in CRC patients were significantly upregulated in peripheral blood, compared with tumor tissues of the same patients. However, demethylation status of all ICs was higher in TT, except for TIGIT in PBC, and CTLA-4 in CRC patients. These data indicate that the underlying mechanisms behind peripheral upregulation of PD-L1 and TIGIT in cancer patients could be due to aberrant promoter methylation profile. Moreover, demethylation inhibitors together with anti-PD-L1/ anti-TIGIT could be a more efficient therapeutic strategy in cancer patients. ARTICLE HISTORY

Soluble HLA-G and HLA-G Bearing Extracellular Vesicles Affect ILT-2 Positive and ILT-2 Negative CD8 T Cells Complementary

“…Besides HLA-G and ILT-2, additional IC molecules such as programmed cell death protein-1 (PD-1), cytotoxic T-lymphocyte-associated protein (CTLA-4), T-cell immunoglobulin and mucin-domain containing-3 (TIM-3), and CD95 are associated in tumor-driven immune escape mechanisms acting locally at the tumor site or systemically in the peripheral blood (24)(25)(26). The continuous upregulation and co-expression of multiple IC, being often observed in cancer and chronic infections, are indicative for an immunosuppressive/exhausted phenotype of T cells and are associated with loss of effector functions and immunosurveillance (27,28).…”

LAG3: The Biological Processes That Motivate Targeting This Immune Checkpoint Molecule in Human Cancer

“…Instead PD-L1 was more frequently detected in TN invasive tumors [75], signifying that the pattern of expression of these immune checkpoint molecules might vary in different phases of the disease (from in situ to invasive). In another study, peripheral blood from BC and colorectal cancer patients, observed LAG3 downregulation in patients with TIM3, TIGIT and PD-L1 upregulation [76], confirming the heterogeneous expression of these molecules also in circulating immune cells, and contributing to the complexity of this scenario.…”

Liquid Biopsies to Evaluate Immunogenicity of Gynecological/Breast Tumors: On the Way to Blood-Based Biomarkers for Immunotherapies

“…Finally, the heterogenous expression between primary tumor and metastatic tissue also limits the use of IHC [47,48]. Blood-based assessment of PD-L1 is conceivable by protein, transcript, mutation, or methyla- In PBMCs Evaluation of PMBCs from BC patients demonstrated that PD-L1 promotor hypomethylation might be the reason for increased PD-L1 expression in PBMCs compared to matched tumor tissue [37]. Furthermore, the PD-1 promotor was shown to be hypermethylated in PBMCs compared to tumor tissue [37].…”

“…Blood-based assessment of PD-L1 is conceivable by protein, transcript, mutation, or methyla- In PBMCs Evaluation of PMBCs from BC patients demonstrated that PD-L1 promotor hypomethylation might be the reason for increased PD-L1 expression in PBMCs compared to matched tumor tissue [37]. Furthermore, the PD-1 promotor was shown to be hypermethylated in PBMCs compared to tumor tissue [37]. Methylation profiling via cfDNA might consequently be considered as molecular correlate for PD-L1 expression.…”