Aspirin inhibits cell stemness of esophageal cancer by downregulation of chemokine CCL2

Abstract

Objective: To investigate the effect of tumor-associated macrophages on the stemness of esophageal cancer cells and the potential mechanism of antiproliferative effects of aspirin (ASA). Methods: The effects of aspirin on the stemness characteristics of KYSE-450 cells and KYSE-450 cells co-cultured with M2 macrophages (KYSE-450+ M2) were performed using spheroid formation assay. After treatment with aspirin, the expression of different chemokines, the core pluripotency gene Nanog and the stem cell marker CD90 in different cell groups were determined by real-time quantitative PCR, flow cytometry and Western blot. Results: The number of spheres formed in the ASA and KYSE-450+ M2 cell groups were 7.00±1.23 and 34.33±2.33, respectively, showing statistically significant difference compared with that of control group (14.50±2.33, all P<0.05). The number of spheres in KYSE-450+ M2+ ASA cell group were 20.67±2.33, which was significantly lower than that of KYSE-450+ M2 group (P<0.05). The expression levels of Nanog gene in control and ASA groups were 1.00 and 0.50±0.10, respectively, and the difference was statistically significant (P<0.05). Moreover, the expression of Nanog gene in cells of KYSE-450+ M2 group and M2+ KYSE-450+ ASA group was 1.74±0.13 and 1.43±0.05, showing statistically significant difference (P<0.05). When chemokine CCL2 was knocked down, the levels of Nanog gene in M2+ shCCL2-KYSE450+ ASA group and M2+ shCCL2-KYSE450 group were decreased to 1.22±0.11 and 1.17±0.08, respectively, and there was no statistically significant difference between them (P=0.69). Flow cytometry analyses showed that the expression levels of CD90 in control and ASA cells were (2.93±0.52)% and (1.30±0.17)%, respectively, and the difference was statistically significant (P<0.05). Moreover, the expression levels of CD90 in M2+ shCCL2-KYSE450 cells and M2+ shCCL2-KYSE450+ ASA cells were (4.07±0.12)% and (4.73±0.38)%, respectively, showing no statistically significant difference (P=0.17). Conclusions: Tumor-associated macrophages enhances the stemness of esophageal cancer cells, whereas aspirin attenuates the stemness by suppressing the expression of CCL2. Aspirin plays an anti-tumor effect in esophageal cancer cells.