Anti-ANXA1 (aa 24-346) polyclonal antibody

The molecular mechanisms underlying constitutive nuclear factor-kappa B (NF-kappa B) activation in solid tumors has not been elucidated. We show that Annexin-1 (ANXA1) is involved in this process, and suppression of ANXA1 in highly metastatic breast cancer cells impedes migration and metastasis capabilities in vitro and in vivo. ANXA1 expression correlates with NF-kappa B activity, suggesting that ANXA1 may be required for the constitutive activity of I kappa B kinase (IKK) and NF-kappa B in highly metatstatic breast cancer. Gel-filtration analysis demonstrated that ANXA1 co-elutes with the members of the IKK complex and NF-kappa B signaling pathway, and immunoprecipitation confirmed that ANXA1 can bind to and interact with IKK gamma or NEMO, but not IKK alpha or IKK beta. Importantly, silencing of ANXA1 prevents the interaction of NEMO and RIP1, which indicates that ANXA1 is required for the recruitment of RIP1 to the IKK complex, which may be important for the activation of NF-kappa B. Downstream targets of NF-kappa B include uPA and CXCR4, which can be modulated by ANXA1 silencing. CXCR4-mediated migration of breast cancer cell lines in response to CXCL12 was significantly modulated by ANXA1, indicating its importance in the tissue-specific migration of breast cancer cells. Chromatin immunoprecipitation experiments confirmed that in ANXA1 overexpressed cells, NF-kappa B was recruited to CXCR4 promoter without external stimulation, indicating that ANXA1 is critical for the constitutive activation of NF-kappa B in breast cancer to promote metastasis. Finally, we show that ANXA1 overexpression enhances metastasis and reduces survival in an intracardiac metastasis model, while ANXA1-deficient mice crossed with MMTV-PyMT mice display significantly less metastasis than their heterozygous littermates, indicating that ANXA1 is an important gene in breast cancer metastasis. Our data reveal that ANXA1 can constitutively activate NF-kappa B in breast cancer cells through the interaction with the IKK complex, and suggests that modulating ANXA1 levels has therapeutic potential to suppress breast cancer metastasis. Oncogene (2011) 30, 3174-3185; doi:10.1038/onc.2011.28; published online 7 March 2011

Annexin A1 (ANXA1) acts either as a tumor suppressor or an oncogene in different tumor types. Several clinical studies revealed that the expression of ANXA1 is associated with the pathologic differentiation grade in oral squamous cell carcinoma (OSCC) patients. However, the direct function of ANXA1 in OSCC progression has remained to be fully clarified. The present study was designed to investigate the role of ANXA1 in OSCC cell proliferation and invasion in vitro. Furthermore, whether ANXA1 was involved in transforming growth factor beta 1 (TGF beta 1)/epidermal growth factor (EGF)-induced epithelial-mesenchymal transition (EMT) in OSCC was explored. Tca-8113 and SCC-9 cells were transfected with ANXA1-pcDNA3.1 plasmid to overexpress ANXA1. Subsequently, cell proliferation and invasion were examined using MTT and Transwell-Matrigel invasion assays. TGF beta 1 and EGF were used to induce EMT in Tca-8113 and SCC-9 cells, and the expression of epithelial (E)-cadherin, neural (N)-cadherin and vimentin was determined by western blot analysis. The results demonstrated that ANXA1 overexpression induced a significant decrease of cell growth and invasiveness in Tca-8113 and SCC-9 cells. The expression of E-cadherin was significantly increased, while the expression of vimentin and N-cadherin was significantly decreased in ANXA1-overexpressing Tca-8113 and SCC-9 cells. ANXA1 expression was significantly decreased in TGF beta 1/EGF-treated cells. Furthermore TGF beta 1/EGF-induced EMT in OSCC cell lines was attenuated by ANXA1 overexpression. In conclusion, to the best of our knowledge, the present study was the first to evidence that ANXA1 inhibits OSCC cell proliferation and invasion in vitro. TGF beta 1/EGF-induced EMT was reversed by ANXA1 in OSCC. ANXA1 was suggested to be a potential marker for OSCC as well as a novel treatment.