Jee S H, Chiu H C, Tsai T F, Tsai W L, Liao Y H, Chu C Y, Kuo M L
Department of Dermatology, National Taiwan University Hospital, Taiwan.
J Invest Dermatol. 2002 Nov;119(5):1121-7. doi: 10.1046/j.1523-1747.2002.19503.x.
Dysregulation of interleukin-6 has been reported to be associated with various types of tumors, and interleukin-6 plays an important part in regulating apoptosis in many types of cells. Previously, Mcl-1 was shown to be significantly increased in interleukin-6-overexpressed basal cell carcinoma cells and conferred on them anti-apoptotic activity. The aim of this study was to investigate which signaling pathway is involved in the anti-apoptotic effect of interleukin-6 on basal cell carcinoma cells. Here we show that the addition of recombinant 100 ng per ml interleukin-6 to basal cell carcinoma cells induced a 2.3-fold increase in the level of Mcl-1 protein in basal cell carcinoma cells. Transfection with dominant-negative STAT3 (STAT3F) into inter-leukin-6-treated basal cell carcinoma cells caused a decrease of phosphotyrosyl STAT3 but did not alter Mcl-1 protein levels; however, AG490, a Janus tyrosine kinase inhibitor, was capable of inhibiting the interleukin-6-induced elevation of Mcl-1 protein. Next, interleukin-6 stimulation elicited extracellular signal-regulated kinase activation in basal cell carcinoma cells, and the mitogen-activated protein kinase inhibitor, PD98059, could affect this response without affecting the interleukin-6-medi-ated Mcl-1 upregulation. Use of the two phosphotidyl inositol 3-kinase inhibitors, LY294002 and wortmannin, to check whether this pathway is involved in Mcl-1 upregulation by interleukin-6, we found that the phosphotidyl inositol 3-kinase inhibitors completely attenuated the interleukin-6-induced Mcl-1 upregulation. Furthermore, in the interleukin-6-overexpressing basal cell carcinoma cell clone, dominant-negative Akt also significantly reduced the increased level of Mcl-1. Interestingly, Janus tyrosine kinase inhibitor, AG490, treatment strongly blocked the phosphotidyl inositol 3-kinase pathway activation, as evidenced by the decrease in phospho-Akt level. Blockage of phosphotidyl inositol 3-kinase/Akt pathway abolished the interleukin-6-mediated anti-apoptotic activity in ultraviolet B treated cells. Unexpectedly, without ultraviolet B irradiation, STAT3F transfection also induced a significant apoptosis in basal cell carcinoma/interleukin-6 cells. Taken together, our data suggest that both the phosphotidyl inositol 3-kinase/Akt and STAT3 pathways are potentially involved in interleukin-6-mediated cell survival activity in basal cell carcinoma cells; however, the upregulation of the anti-apoptotic Mcl-1 protein by interleukin-6 is mainly through the Janus tyrosine kinase/phosphotidyl inositol 3-kinase/Akt, but not the STAT3 pathway.
据报道，白细胞介素-6失调与多种类型的肿瘤相关，且白细胞介素-6在调节多种细胞的凋亡中起重要作用。此前研究表明，在白细胞介素-6过表达的基底细胞癌细胞中，Mcl-1显著增加，并赋予它们抗凋亡活性。本研究的目的是探究白细胞介素-6对基底细胞癌细胞抗凋亡作用涉及哪条信号通路。在此我们发现，向基底细胞癌细胞中添加每毫升100纳克的重组白细胞介素-6，可使基底细胞癌细胞中Mcl-1蛋白水平增加2.3倍。将显性负性STAT3（STAT3F）转染到经白细胞介素-6处理的基底细胞癌细胞中，可使磷酸化酪氨酸STAT3水平降低，但不改变Mcl-1蛋白水平；然而，Janus酪氨酸激酶抑制剂AG490能够抑制白细胞介素-6诱导的Mcl-1蛋白升高。接下来，白细胞介素-6刺激可引起基底细胞癌细胞中细胞外信号调节激酶激活，丝裂原活化蛋白激酶抑制剂PD98059可影响这一反应，而不影响白细胞介素-6介导的Mcl-1上调。使用两种磷脂酰肌醇3-激酶抑制剂LY294002和渥曼青霉素来检测该通路是否参与白细胞介素-6介导的Mcl-1上调，我们发现磷脂酰肌醇3-激酶抑制剂完全减弱了白细胞介素-6诱导的Mcl-1上调。此外，在白细胞介素-6过表达的基底细胞癌细胞克隆中，显性负性Akt也显著降低了Mcl-1升高的水平。有趣的是，Janus酪氨酸激酶抑制剂AG490处理强烈阻断了磷脂酰肌醇3-激酶通路的激活，磷酸化Akt水平降低证明了这一点。阻断磷脂酰肌醇3-激酶/Akt通路消除了白细胞介素-6介导的紫外线B处理细胞中的抗凋亡活性。出乎意料的是，在没有紫外线B照射的情况下，STAT3F转染也在基底细胞癌/白细胞介素-6细胞中诱导了显著的凋亡。综上所述，我们的数据表明，磷脂酰肌醇3-激酶/Akt和STAT3通路都可能参与白细胞介素-6介导的基底细胞癌细胞存活活性；然而，白细胞介素-6对抗凋亡Mcl-1蛋白的上调主要是通过Janus酪氨酸激酶/磷脂酰肌醇3-激酶/Akt，而非STAT3通路。
