拮抗CC趋化因子受体5信号诱导肿瘤细胞凋亡并调节肿瘤微环境抑制肿瘤生长

CCR5 blockade reduces tumor growth by inducing apoptosis and impairing immunosuppression of tumor microenvironment

目的探索拮抗CC趋化因子受体5(CCR5)信号通路对肿瘤生长和肿瘤微环境的影响。方法采用CCK8细胞毒试验研究CCR5选择性拮抗剂Maraviroc体外对小鼠Lewis肺腺癌细胞增殖的影响,并运用流式细胞术和RT-PCR检测肿瘤细胞凋亡和Caspase 8基因的表达。然后采用免疫荧光组织化学染色法研究了Maraviroc对小鼠体内肿瘤生长和肿瘤微环境中CD4^(+)和CD8^(+)以及Foxp3^(+)细胞比例的影响。结果拮抗CCR5信号在体内外均能够抑制癌细胞的生长。体外研究发现:CCR5拮抗剂可通过增强凋亡基因Caspase 8表达而诱导肿瘤细胞凋亡。在小鼠体内,CCR5拮抗剂可明显增加肿瘤微环境中CD4^(+)和CD8^(+)细胞的浸润而减少Foxp3^(+)细胞的浸润。结论拮抗CCR5信号可能通过诱导肿瘤细胞凋亡,逆转免疫抑制性肿瘤微环境而抑制肿瘤生长。

Objective The present study aimed to explore the effects of CC⁃chemokine receptor 5 antagonism on tumor growth and immune microenvironment.Methods Cell Counting Kit⁃8 was used to detect in vitro anti⁃proliferation activity of maraviroc,a selective CC⁃chemokine receptor 5 inhibitor,on Lewis cells,a mouse lung adenocarcinoma cell strain.Flow cytometry and real⁃time quantitative PCR were respectively used to detect cell apop⁃tosis and Caspase 8 gene expression.In a congenic mouse lung cancer model,the mice were intraperitoneally admin⁃istered with maraviroc or vehicle.Tumor sizes were measured and tumor infiltrating CD4^(+),CD8^(+)and Foxp3^(+)cells were determined by immunofluorescent staining.Results Our results showed that maraviroc could inhibit the growth of Lewis cancer cells not only in vitro but also in vivo.This in⁃vitro inhibition was presumably attributable to apoptosis induction by the enhancement of Caspase 8 gene expression after maraviroc blockade.Additionally,more CD4^(+)and CD8^(+)cells but less Foxp3^(+)cells were detected in tumor mass from the mice administered with maraviroc.Conclusions Taken together,it can be speculated that CCR5 blockade may inhibit the growth of Lewis cells by inducing cell apoptosis and impairing the immunosuppressive tumor microenvironment.It is worthy of further investi⁃gation as a candidate for cancer therapy.