Immune response and evasion mechanisms in lip carcinogenesis: An immunohistochemical study

• Published in: Archives of oral biology Vol. 98; p. 99
• Main Authors: Lopes, Maria Luiza Diniz de Sousa, Gonzaga, Amanda Katarinny Goes, Mosconi, Carla, Palomino, Gustavo Martelli, Mendonça, Elismauro Francisco, Batista, Aline Carvalho, Silveira, Éricka Janine Dantas da
• Format: Journal Article
• Language: English
• Published: England 01.02.2019
• Subjects: PD-L1; Squamous cell carcinoma; Cheilitis, lip carcinogenesis; Tumor-infiltrating lymphocytes; HLA-G
• ISSN: 1879-1506
• DOI: 10.1016/j.archoraibio.2018.09.017

Programmed death ligand-1 (PD-L1) and human leukocyte antigen-G (HLA-G) are considered immune checkpoint molecules that inhibit T-cell effectiveness, contributing to tumor immune escape. This study investigated PD-L1, HLA-G, CD8, and granzyme B (GrB) expression at different stages of lip carcinogenesis. Forty cases of lip squamous cell carcinoma (LSCC), 55 actinic cheilitis (AC), and 10 healthy lip mucosa (HLM) were submitted to immunohistochemistry. Semiquantitative (PD-L1, HLA-G), and quantitative (CD8, GrB) analysis were performed. PD-L1 and HLA-G expression in neoplastic cells/keratinocytes and stroma/connective tissue was significantly higher in LSCC and AC, compared to HLM (p<0.05). PD-L1 was not associated with clinicopathological features of the lesions. HLA-G expression by malignant cells was significantly higher in LSCCs with distant metastasis (p = 0.041).CD8 and GrB cell numbers progressively increased from HLMs to LSCC, with AC exhibiting intermediate numbers (p<0.01). Most LSCCs showed coexistence of PD-L1 and CD8 cells (72.5%). PD-L1 was directly correlated to CD8 and GrB lymphocytic infiltration in LSCCs (p<0.05). Low cytotoxic immune response was associated with lymph node metastasis in LSCC (p<0.05). PD-L1 and HLA-G-mediated immune evasion mechanisms are likely to occur from early pre-malignant to advanced malignant stages of lip carcinogenesis, which might provide a rationale for therapeutic blockade of these pathways. PD-L1 expression in LSCCs was correlated with the cytotoxic markers, suggesting that PD-L1 may appear as an escape mechanism in response to an active antitumor response.