Breast Oncology Centre, Shandong Tumor Hospital and Institute, Shandong Academy of Medical Sciences, Jinan 250117, PR China.
Oncol Rep. 2013 Feb;29(2):812-8. doi: 10.3892/or.2012.2159. Epub 2012 Nov 29.
Lapatinib is highly active against breast cancer with HER2 overexpression in preclinical and clinical settings. Constitutive activation of NF-κB is linked to proliferation and apoptosis in breast cancer cells. NF-κB can be activated by HER2 in breast cancer cells. However, the effect of lapatinib on NF-κB activity is not completely clear. In this study, we showed that lapatinib potently inhibited activation of NF-κB in HER2-overexpressing breast cancer cells, including SKBR3 and MDA-MB-453; but not in non-HER2-overexpressing breast cancer cells, MDA-MB-231, MDA-MB-468 and MDA-MB‑435. In addition, we established a model of acquired resistance to lapatinib by chronically challenging SKBR3 breast cancer cells with increasing concentrations of lapatinib. EMSA assays showed that there was decreased NF-κB activity in the resistant cells. Western blot analysis showed that lapatinib reduced the phosphorylation of IκB-α in a time- and dose-dependent manner in SKBR3 cells. Furthermore, the expression level of p-IκB-α protein was markedly decreased in the resistant cells, compared with the parental SKBR3 cells. Additionally, treatment with the PI3K inhibitor LY294002 dramatically inhibited activation of NF-κB in HER2-overexpressing breast cancer cells. Moreover, LY294002 inhibited phosphorylation of Akt and IκB-α in SKBR3 cells. Our results suggest that lapatinib potently inhibits the activation of NF-κB in HER2-overexpressing breast cancer cells. Lapatinib appears to inactivate NF-κB through reducing phosphorylation of IκB-α via blocking the PI3K/Akt cascade.
拉帕替尼在临床前和临床环境中对 HER2 过表达的乳腺癌具有高度活性。NF-κB 的组成性激活与乳腺癌细胞的增殖和凋亡有关。NF-κB 可以在乳腺癌细胞中被 HER2 激活。然而，拉帕替尼对 NF-κB 活性的影响尚不完全清楚。在这项研究中，我们表明拉帕替尼能有效地抑制 HER2 过表达的乳腺癌细胞（包括 SKBR3 和 MDA-MB-453）中 NF-κB 的激活；但对非 HER2 过表达的乳腺癌细胞（MDA-MB-231、MDA-MB-468 和 MDA-MB-435）则没有这种作用。此外，我们通过用递增浓度的拉帕替尼长期挑战 SKBR3 乳腺癌细胞，建立了对拉帕替尼获得性耐药的模型。EMSA 检测表明，耐药细胞中 NF-κB 的活性降低。Western blot 分析表明，拉帕替尼以时间和剂量依赖的方式减少 SKBR3 细胞中 IκB-α的磷酸化。此外，耐药细胞中 p-IκB-α 蛋白的表达水平明显低于亲本 SKBR3 细胞。此外，用 PI3K 抑制剂 LY294002 处理可显著抑制 HER2 过表达的乳腺癌细胞中 NF-κB 的激活。此外，LY294002 抑制 SKBR3 细胞中 Akt 和 IκB-α的磷酸化。我们的结果表明，拉帕替尼能有效地抑制 HER2 过表达的乳腺癌细胞中 NF-κB 的激活。拉帕替尼似乎通过阻断 PI3K/Akt 级联反应来减少 IκB-α的磷酸化，从而使 NF-κB 失活。
