Abstract 4983: IRAK4 and breast cancer cell migration in culture and zebrafish xenografts
Authors: Kimbro K. Sean , Ferri-Lagneau Karine , Haider Jamil , Yeyeodu Susan , Yang Xiaohe , Leung TinChung 
Published: May 2015

Growing evidence indicates that incongruities in the inflammatory and immune response pathways contribute to tumorigenesis. We seek to explore the underlying biological mechanisms that both promote and inhibit breast cancer (BrCa) tumorigenesis via innate immune pathways involving the Toll-like receptors (TLRs) and their associated agonists. Women of African descent (AA) are an understudied group at high risk for developing aggressive BrCa. Therefore, we previously examined the occurrence of single nucleotide polymorphisms (SNPs) in selected genes along TLR pathways among a small cohort of AA women with breast cancer and identified a SNP in the central regulatory kinase IRAK4 that was associated with increased breast cancer risk. In silico predictions suggest that the IRAK4 minor variant rs4251545 codes for an Ala428Thr missense mutation that introduces a potential phosphorylation site in the extreme carboxy terminus (XCT) of the IRAK-4 kinase domain. The current study tests the hypothesis that functional IRAK4 promotes BrCa cell growth and migration using in vitro (cultured human BrCa cell) and in vivo (zebrafish BrCa xenograft) models.

Materials and methods: ER-positive MCF7 and triple-negative MDA-MB-231 (wild-type IRAK4) and MDA-MB-468 (IRAK4 w/rs4251545) human BrCa cell lines were compared. Cultured cells were treated for 24 hours with or without IRAK1/4 inhibitor. Cell migration and cell growth among BrCa lines were compared using wound healing and crystal violet assays, respectively. BrCa cell xenografts of zebrafish (ZF) embryos were examined for metastatic potential and the physiologic effects of morpholino inhibition of ZF IRAK4 among embryos with and without BrCa xenograft burdens were compared. In addition, zebrafish/tumor xenograft model was used to address the in vivo metastatic property of BrCa cells and the effect of targeting zebrafish irak4 using morpholino (MO) knockdown approach in the tumor-host environment on the metastatic behavior of MDA-MB-468 cells.

Results: Treatment with IRAK1/4 inhibitor delayed BrCa migration and growth in all BrCa cells lines. Relative in vivo migration rates/ (or metastatic property) of MDA-MB-231 and MDA-MB-468 BrCa xenografts in ZF resemble in vitro rates, in which MDA-MB-231s migrate metastasized more rapidly/ (or aggressively). MO inhibition of ZF zebrafish IRAK4 irak4 gene expression in the host environment MDA-MB-468 xenografted fish inhibits MDA-MB-468 metastasis in the zebrafish/tumor xenograft.

Conclusion: Inhibition of IRAK4 reduces BrCa growth and migration in vitro and in vivo in zebrafish. The development of drugs that target IRAK4 and other regulators of the innate immune pathway may help modulate BrCa tumor progression.

Citation Format: K. Sean Kimbro, Karine Ferri-Lagneau, Jamil Haider, Susan Yeyeodu, Xiaohe Yang, TinChung Leung. IRAK4 and breast cancer cell migration in culture and zebrafish xenografts. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4983. doi:10.1158/1538-7445.AM2014-4983