核转录因子κB激活对雌激素受体阴性乳腺癌细胞增殖的影响

目的研究雌激素受体（ER）阴性乳腺癌细胞株中核转录因子κB的激活途径及其促进肿瘤细胞增殖的机制。方法以蛋白印迹法和流式细胞技术研究不同受体类型乳腺癌细胞株IκB激酶α表达、不同处理因素对雌激素受体阴性细胞株MDA-MB-435S细胞周期的影响,以及抑制核转录因子κB对细胞增殖的影响。结果雌激素受体阴性细胞株中的IκB激酶α表达高于受体阳性细胞株,而在MDA-MB-435S中促进细胞增殖因素的研究中,表皮生长因子作用最显著,它能提高细胞周期蛋白D1表达,较对照组增加83％,促细胞增殖指数由0．22提高至0．31（P〈0．01）,而应用蛋白激酶C抑制剂C06976抑制核转录因子κB激活,可显著抑制表皮生长因子的促细胞增殖作用。结论表皮生长因子的促雌激素受体阴性乳腺癌细胞增殖信号可通过激活核转录因子κB提高细胞周期蛋白D1表达,促进了肿瘤细胞增殖。核转录因子κB起了增殖信号递呈作用,针对核转录因子κB激活的治疗可提供乳腺癌全新的治疗靶点。

The nuclear factor kappa B activation: the key step of cell proliferation in estrogen receptor-negative breast cancer cells

OBJECTIVE: To investigate the way of nuclear factor kappa B (NF-kappaB) activation and the mechanism of NF-kappaB-promoted proliferation in estrogen receptor (ER)-negative breast cancer cells. METHODS: The protein of IkappaB kinase alpha (IKKalpha) was measured by Western blot and the influence on cell-cycle was assayed by flow cytometry (FCM). RESULTS: The IKKalpha was tested higher in three ER-negative breast cancer cell lines than in MCF-7. The influence caused by epidermal growth factor (EGF), tumor necrosis factor (TNF)-alpha and E(2) to tumor cells' proliferation was tested. EGF could remarkably enhance cyclin D(1) expression about 83% more in EGF group than that in control group and proliferation index from 0.22 to 0.31 (P < 0.01). On the other hand, TNF-alpha inhibited cyclin D(1) expression. Protein kinase C inhibitor, Go6976, could peculiarly prevent NF-kappaB over-expression caused by EGF. The cell-cycle was assayed by FCM in phase G(0)/G(1) 69.36% and in phase S 22.77% when adding EGF and in phase G(0)/G(1) 91.54% and in phase S 7.81% when adding EGF and Go6976. The proliferation index decreased from 0.31 to 0.09 (P < 0.01). CONCLUSIONS: EGF-EGFR pathway can provide ER-negative breast cancer cells the signal for the autonomous growth. This signal promoted tumor cells' proliferation is transmitted by activating NF-kappaB and expressing more cyclin D(1). In this pathway, NF-kappaB play an important role as signal transmitting. The strategy to NF-kappaB activating may provide new way to treat ER-negative breast cancers.