Van Laere Steven J, Van der Auwera Ilse, Van den Eynden Gert G, Elst Hilde J, Weyler Joost, Harris Adrian L, van Dam Peter, Van Marck Eric A, Vermeulen Peter B, Dirix Luc Y
Translational Cancer Research Group (Laboratory of Pathology, University of Antwerp and Oncology Center, General Hospital Sint-Augustinus), Wilrijk, Belgium.
Clin Cancer Res. 2006 Jun 1;12(11 Pt 1):3249-56. doi: 10.1158/1078-0432.CCR-05-2800.
Inflammatory breast cancer (IBC) is the most aggressive form of locally advanced breast cancer with high metastatic potential. In a previous study, we showed that IBC is a different form of breast cancer compared with non-IBC by cDNA microarray analysis. A list of 756 genes with significant expression differences between IBC and non-IBC was identified. In-depth functional analysis revealed the presence of a high number of nuclear factor-kappaB (NF-kappaB) target genes with elevated expression in IBC versus non-IBC. This led to the hypothesis that NF-kappaB contributes to the phenotype of IBC. The aim of the present study was to further investigate the role of NF-kappaB in IBC.
Immunohistochemistry and NF-kappaB DNA-binding experiments were done for all NF-kappaB subunits (RelA, RelB, cRel, NFkB1, and NFkB2) using IBC and non-IBC specimens. Transcriptionally active NF-kappaB dimers were identified by means of coexpression analysis. In addition, quantitative real-time reverse transcription-PCR for eight NF-kappaB target genes, selected upon a significant, 3-fold gene expression difference between IBC and non-IBC by cDNA microarray analysis, was done.
We found a significant overexpression for all of eight selected NF-kappaB target genes in IBC compared with non-IBC by quantitative real-time reverse transcription-PCR. In addition, we found a statistically elevated number of immunostained nuclei in IBC compared with non-IBC for RelB (P = 0.038) and NFkB1 (P < 0.001). Immunohistochemical data were further validated by NF-kappaB DNA-binding experiments. Significant correlations between immunohistochemical data and NF-kappaB DNA binding for RelA, RelB, NFkB1, and NFkB2 were found. Transcriptionally active NF-kappaB dimers, composed of specific combinations of NF-kappaB family members, were found in 19 of 44 IBC specimens compared with 2 of 45 non-IBC specimens (P < 0.001). In addition, we found evidence for an estrogen receptor (ER)-mediated inhibition of the NF-kappaB signaling pathway. NF-kappaB target genes were significantly elevated in ER- versus ER+ breast tumors. Also, the amount of immunostained nuclei for RelB (P = 0.025) and NFkB1 (P = 0.031) was higher in ER- breast tumors versus ER+ breast tumors.
The NF-kappaB transcription factor pathway probably contributes to the phenotype of IBC and possibly offers new options for treatment of patients diagnosed with this aggressive form of breast cancer.
炎性乳腺癌（IBC）是局部晚期乳腺癌中最具侵袭性的类型，具有较高的转移潜能。在之前的一项研究中，我们通过cDNA微阵列分析表明，IBC与非IBC是乳腺癌的不同形式。鉴定出了756个在IBC和非IBC之间具有显著表达差异的基因。深入的功能分析显示，与非IBC相比，IBC中有大量核因子-κB（NF-κB）靶基因表达升高。这导致了NF-κB促成IBC表型的假说。本研究的目的是进一步探究NF-κB在IBC中的作用。
使用IBC和非IBC标本对所有NF-κB亚基（RelA、RelB、cRel、NFkB1和NFkB2）进行免疫组织化学和NF-κB DNA结合实验。通过共表达分析鉴定转录活性NF-κB二聚体。此外，对通过cDNA微阵列分析在IBC和非IBC之间具有显著的3倍基因表达差异而选择的8个NF-κB靶基因进行定量实时逆转录-PCR。
通过定量实时逆转录-PCR，我们发现与非IBC相比，IBC中所有8个选定的NF-κB靶基因均有显著过表达。此外，我们发现与非IBC相比，IBC中RelB（P = 0.038）和NFkB1（P < 0.001）的免疫染色细胞核数量在统计学上有所增加。免疫组织化学数据通过NF-κB DNA结合实验得到进一步验证。发现RelA、RelB、NFkB1和NFkB2的免疫组织化学数据与NF-κB DNA结合之间存在显著相关性。在44个IBC标本中有19个发现了由NF-κB家族成员的特定组合组成的转录活性NF-κB二聚体，而在45个非IBC标本中只有2个（P < 0.001）。此外，我们发现有证据表明雌激素受体（ER）介导对NF-κB信号通路的抑制。与ER+乳腺肿瘤相比，ER-乳腺肿瘤中NF-κB靶基因显著升高。同样，ER-乳腺肿瘤中RelB（P = 0.025）和NFkB1（P = 0.031）的免疫染色细胞核数量高于ER+乳腺肿瘤。
NF-κB转录因子途径可能促成IBC的表型，并可能为诊断为这种侵袭性乳腺癌的患者提供新的治疗选择。
