Objective: To investigate the expression and significance of CCL5 in patients with esophageal carcinoma.
Methods: Using reverse transcriptase polymerase chain reaction (RT-PCR), the expressions of CCL5/CD8/granzyme B/perforin in tumor and corresponding adjacent tissues from esophageal carcinoma patients were examined. Flow cytometry (FACS) was used to detect the percentages of CD8(+) T cells and CCR5(+)CD8(+) T cells in TIL and PBMC from the patients. Transwell assay was performed to study the effect of CCL5 on the migration of T cells in vitro. T test and Spearman correlation analysis were performed.
Results: The mRNA expressions of CCL5 and perforin were 0.348 2 ± 0.300 1 and 0.181 9 ± 0.118 6, respectively, in the tumor samples, while their expressions in adjacent samples were 0.279 6 ± 0.138 0 and 0.118 0 ± 0.109 8, respectively, with no statistically significant differences between them (P > 0.05 for both). The mRNA expressions of CD8 and granzyme B were significantly higher in the tumor tissues than in adjacent tissues (0.464 9 ± 0.300 8 vs. 0.279 0 ± 0.173 4, 0.648 7 ± 0.516 0 vs. 0.469 7 ± 0.259 1; P < 0.05 for both). The relative expression of CCL5 was positively correlated with that of CD8, perforin and granzyme B (r(CD8) = 0.272, P = 0.034; r(perforin) = 0.305, P = 0.026; r(granzymeB) = 0.108, P = 0.012) in the tumor sites. FACS data revealed that the proportions of CD8(+) T cells in TIL and PBMC were (45.86 ± 16.09)% and (34.05 ± 15.07)%, respectively, showing a significant difference (P = 0.022). Similarly, CCR5(+)CD8(+) T cells fraction in TIL (48.12 ± 26.75)% was much higher than that in PBMC (19.53 ± 13.67) % (P < 0.001). Transwell assay showed that CCL5 protein enhanced the migration of T cells, supporting that CCL5 is crucial for CD8(+) T cells recruitment in vivo. Intriguingly, CCL5 expression was down-regulated in advanced patients (stage IIb-IV). The accumulation of CD8(+) T cells and CCR5(+)CD8(+) T cells was strongly reduced in advanced patients, suggesting that CCL5 expression may be involved in the local control of the disease and its reduction may be involved in disease progression.
Conclusions: The current data indicate the involvement of CCL5 in the regulation of CD8(+) T cell entry into tumor lesions in esophageal carcinoma patients. This process may affect the disease status and potentially as a prognostic factor for cancer patients. Enhancing local CCL5 expression in tumor lesions may represent a novel strategy in esophageal cancer therapy.