[Production and mechanism of CCL5 by macrophages in U14 cervical cancer-bearing mice during infection]

Abstract

Objective: To investigate the production and mechanism of chemokine (C-C motif) ligand 5 (CCL5) by macrophages in U14 cervical cancer-bearing mice during infection.

Methods: The U14 cervical cancer cells were injected in C57BL/6 mice to induce tumor-bearing condition. Lipopolysaccharide (LPS) was injected into C57BL/6 mice to induce infection. The protein expression of CCL5 in the serum and the CCL5 mRNA expression in inflammatory cells were measured by ELISA and fluorescence quantitative-PCR in four groups. Macrophages were induced in the tumor conditioned medium (TCM) which extracted from mice serum. The protein expression levels of CCL5, prostaglandin E2 (PGE2) and cyclic adenosine monophosphate (cAMP) in the medium and CCL5, PGE2 and cAMP mRNA expression in the macrophages were detected in different groups. In order to determine whether the inhibition was related to PGE2, selective cyclooxygenase 2(COX-2) inhibitor NS398 was used to reverse this phenomenon and protein kinase A (PKA) inhibitor H89 demonstrated the mechanism through blocking cAMP/PKA signaling pathway.

Results: (1) The protein and mRNA level of CCL5 in tumor-bearing mice were respectively (151 ± 35) pg/ml and 1.0, which were lower than those in the tumor-free mice (691 ± 85) pg/ml and 4.5 ± 0.8, there were significant difference between them (all P < 0.05). The protein and mRNA level of PGE2 in tumor-bearing mice were (1 198 ± 83) pg/ml and 5.8 ± 0.8, which were higher than those in the tumor-free mice (187 ± 25) pg/ml and 1.0, the difference were significant (all P < 0.05). The protein and mRNA level of CCL5 in tumor-free + LPS mice were (4 049 ± 141) pg/ml and 31.5 ± 2.0, which were higher than those in the tumor-bearing + LPS mice (1 951 ± 71) pg/ml and 12.1 ± 2.8, the difference were also significant (P < 0.05). The protein and mRNA level of PGE2 in tumor-free + LPS mice were (676 ± 70) pg/ml and 3.4 ± 0.4, which were lower than those in tumor-bearing + LPS mice (2 550 ± 382) pg/ml and 11.6 ± 0.9, the difference were also significant (all P < 0.05). (2) Macrophages were cultured in vitro using TCM derived from mice. The protein and mRNA level of CCL5 in tumor-bearing mice TCM were respectively (1 626 ± 177) pg/ml and 28.6 ± 1.2, which were higher than those in the tumor-free mice TCM [(27 ± 3) pg/ml and 1.0], there were significant difference (P < 0.05). The protein and mRNA level of PGE2 in tumor-bearing mice TCM were (790 ± 156) pg/ml and 1.7 ± 0.3, which were higher than those in the tumor-free mice TCM [(448 ± 115) pg/ml, 1.0], the difference were significant (all P < 0.05). The protein and mRNA level of cAMP in tumor-bearing mice TCM were (164 ± 30) pg/ml and 1.6 ± 0.3, which weres higher than those in the tumor-free mice TCM [(118 ± 25) pg/ml,1.0], the difference were significant (all P < 0.05). The protein and mRNA level of CCL5 in tumor-free + LPS mice TCM were (10 475 ± 742) pg/ml and 212.0 ± 5.7, which were higher than those in the tumor-bearing + LPS mice TCM [(6 375 ± 530) pg/ml, 142.3 ± 2.5], the difference were significant (all P < 0.05). The protein and mRNA level of PGE2 in tumor-free + LPS mice TCM were (2 438 ± 95) pg/ml and 4.3 ± 0.7, which weres lower than those in the tumor-bearing + LPS mice TCM [(3 441 ± 163) pg/ml, 5.9 ± 0.3], the difference were significant (all P < 0.05). The protein and mRNA level of cAMP in tumor-free + LPS mice TCM were (340 ± 13) pg/ml and 4.1 ± 0.4, which were lower than those in the tumor-bearing + LPS mice TCM [(542 ± 42) pg/ml, 5.4 ± 0.5], the difference were significant (all P < 0.05). (3) Using COX-2 inhibitor NS398 in the tumor-bearing + LPS mice, the protein and mRNA level of CCL5, PGE2 and cAMP were (7 691 ± 269) pg/ml and 159.0 ± 8.9, (2 820 ± 152) pg/ml and 4.9 ± 0.3, (465 ± 8) pg/ml and 4.3 ± 0.4, respectively, and there were significant difference (all P < 0.05), compared to before treatment. Using PKA inhibitor H89 in the tumor-bearing + LPS mice, the protein and mRNA level of CCL5, PGE2 and cAMP were (8 375 ± 520) pg/ml and 177.0 ± 8.8, (2 650 ± 35) pg/ml and 4.7 ± 0.4, (368 ± 13) pg/ml and 3.1 ± 0.7, respectively, and there were significant difference (all P < 0.05), compared to before treatment.

Conclusion: TCM of U14 cells activated macrophages to release PGE2 could inhibit the expression of CCL5 levels by cAMP/PKA signaling pathway.