Nuclear Factor-κB Signature of Inflammatory Breast Cancer by cDNA Microarray Validated by Quantitative Real-time Reverse Transcription-PCR, Immunohistochemistry, and Nuclear Factor-κB DNA-Binding

• Published in: Clinical cancer research Vol. 12; no. 11; pp. 3249 - 3256
• Main Authors: 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
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01.06.2006
• Subjects: Antineoplastic agents; Biological and medical sciences; Gynecology. Andrology. Obstetrics; immunohistochemistry; inflammatory breast cancer; Mammary gland diseases; Medical sciences; microarray; NF-κB; Pharmacology. Drug treatments; quantitative real-time RT-PCR; Tumors; Immunohistochemistry; Inflammation; Breast cancer; Malignant tumor; Real time; Mammary gland diseases; Anatomic pathology; Complementary DNA; Gene; Transcription factor NFκB; Molecular biology; Reverse transcription polymerase chain reaction; Quantitative analysis
• ISSN: 1078-0432; 1557-3265
• DOI: 10.1158/1078-0432.CCR-05-2800

Purpose: 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-κB (NF-κB) target genes with elevated expression in IBC versus non-IBC. This led to the hypothesis that NF-κB contributes to the phenotype of IBC. The aim of the present study was to further investigate the role of NF-κB in IBC. Experimental Design: Immunohistochemistry and NF-κB DNA-binding experiments were done for all NF-κB subunits (RelA, RelB, cRel, NFkB1, and NFkB2) using IBC and non-IBC specimens. Transcriptionally active NF-κB dimers were identified by means of coexpression analysis. In addition, quantitative real-time reverse transcription-PCR for eight NF-κB target genes, selected upon a significant, 3-fold gene expression difference between IBC and non-IBC by cDNA microarray analysis, was done. Results: We found a significant overexpression for all of eight selected NF-κB 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-κB DNA-binding experiments. Significant correlations between immunohistochemical data and NF-κB DNA binding for RelA, RelB, NFkB1, and NFkB2 were found. Transcriptionally active NF-κB dimers, composed of specific combinations of NF-κB 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-κB signaling pathway. NF-κB 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. Conclusions: The NF-κB 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.