Human oral squamous cell carcinoma (OSCC) constitutes an inflammatory microenvironment enriched with chemokines such as CCL20， which promote cancer cell invasion and tumor progression. We found that in OSCC there is a correlation between the expression of and mRNA. Therefore， we hypothesized that OSCC may favor the recruitment and retention of regulatory T (Treg) cells that express the CCL20 receptor， CCR6. Interestingly， most (～60%) peripheral blood Treg cells express CCR6， and CCR6 Treg cells exhibit an activated effector/memory phenotype. In contrast， a significant portion (>30%) of CCR6 Treg cells were found to be CD45RA naive Treg cells. Compared to CCR6 naive or memory Treg cells， CCR6 T... More
Human oral squamous cell carcinoma (OSCC) constitutes an inflammatory microenvironment enriched with chemokines such as CCL20， which promote cancer cell invasion and tumor progression. We found that in OSCC there is a correlation between the expression of and mRNA. Therefore， we hypothesized that OSCC may favor the recruitment and retention of regulatory T (Treg) cells that express the CCL20 receptor， CCR6. Interestingly， most (～60%) peripheral blood Treg cells express CCR6， and CCR6 Treg cells exhibit an activated effector/memory phenotype. In contrast， a significant portion (>30%) of CCR6 Treg cells were found to be CD45RA naive Treg cells. Compared to CCR6 naive or memory Treg cells， CCR6 Treg cells exhibit stronger suppressive activity and display higher FOXP3 expression along with lower methylation at the Treg-specific demethylated region of the gene. This predominance of CCR6 Treg cells was also found in the draining lymph nodes and tumor-infiltrating lymphocytes of OSCC patients with early or late clinical staging. Moreover， CCR6 Treg cells isolated from tumor-infiltrating lymphocytes or draining lymph nodes maintained similar phenotypic and suppressive characteristics ex vivo as did their counterparts isolated from peripheral blood. These results suggest that CCR6 marks activated effector or memory Treg phenotypes with superior suppressive activity in humans.
