活化CD40信号上调胃癌细胞株PD-L1表达及其生物学功能

CD40 activation up-regulates PD-L1 expression on gastric cancer cells and its biological significance

目的观察CD40信号活化后胃癌细胞株增殖凋亡及其表面分子的变化情况并探讨其生物学意义。方法以高表达CD40分子的胃癌细胞株AGS和低表达CD40分子的BGC-823为研究对象,以可溶性CD40配体(sCD40L)激发细胞CD40信号,流式细胞术测定激发CD40信号前后胃癌细胞表面PD-L1分子的表达情况和CD8+T淋巴细胞的表型变化;采用台盼蓝染色法比较CD40活化前后胃癌细胞对CD8+T淋巴细胞的抑制效应。结果 1)CD40信号活化可以诱导高表达CD40分子的胃癌细胞株AGS周期阻滞;2)CD40信号活化可上调AGS细胞表面PD-L1分子的表达,而对低表达CD40分子的细胞BGC-823无上调效应。3)AGS细胞表面PD-L1分子上调明显抑制CD8+T淋巴细胞的增殖并下调其表面CD25分子的表达。结论 CD40信号活化可上调胃癌细胞表面PD-L1表达,继而诱导效应细胞的数量和功能下降,最终有利于胃癌发生免疫逃逸。

This paper aimed to observe proliferation, apoptosis, and surface molecules changes of gastric cancer cell after activation of CD40 signaling, and evaluate its biological significance. Firstly gastric cancer cell lines AGS with high expression of CD40 and BGC-823 but low expression of CD40 were stimulated with soluble CD40 ligand （sCD40L）. Then PD-L1 molecules expression and CD8 ＋ T lymphocytes phenotypic changes were measured by flow cytometry before and after CD40 signal molecule activation. Finally, trypan blue staining method was employed to evaluate the inhibitory effects of gastric cancer cell lines AGS with high expression of the PD-L1 molecule on CD8＋ T lymphocytes. We got the following results： l） CD40 signal activation can induce cycle arrest of gastric cancer cell line AGS with high expression of CD40; 2） CD40 signal activation could up-regulate cell surface molecule expression of PD-L1 on AGS with high expression of CD40, but no effective for BGC-823 with low expression of CD40; 3） AGS could inhibit the proliferation and down-regulate expression of the CD25 molecule of CD8＋T lymphocytes significantly through cell surface PD-L1 molecules. In conclusion, CD40 signal activation can up-regulate the expression of PD-L1 on gastric cancer cell surface, and then induce decline in the number and function of tumor-killing T cells, and ultimately contribute to gastric cancer immune escape.