Abstract P3-09-03: RelB facilitates cell migration and invasion in breast cancer via MMP1 upregulation

Abstract

Abstract Background: RelB is a subunit of the nuclear factor-κB (NF-κB) signaling famliy and appears aberrant expression in breast cancer. The aim of the present study was to further investigate the role of RelB in breast cancer and whether RelB might be a therapeutic target. Methods: 120 cases of breast cancer patients were collected from the Jiangsu Province Hospital during 2015-2017. Immunohistochemistry (IHC) was performed to detect RelB expression in breast cancer tissues and para-cancer tissues. The relationship between RelB expression and clinical pathologic parameters were investigated. Detection the expression of RelB in 4 kinds of human breast cancer cell lines (MCF-7, T47D, MDA-MB-231, BT-549) by Western blot and RT-qPCR.Knockout of RelB in TNBC cell lines (BT-549 and MDA-MB-231) was using the CRISPR/Cas9 genome editing system. CCK-8 and flow cytometry were performed to observe the proliferation, cycle and apoptosis of MDA-MB-231 and BT-549 after knockout of RelB. Transwell and wound healing experiments were performed to observe cell invasion and migration ability. RT-PCR and Western blotting were performed to detect the expression of mRNA and protein of EMT marker and MMP1 respectively. The luciferase reporter gene was performed to detect whether RelB binding with MMP1 promoter region. In vivo efficacy was tested using the xenograft model and lung metastasis model. Results: RelB was highly expressed in triple-negative breast cancer (TNBC) tissues compared with that in adjacent tissues. RelB levels were remarkably associated with the pTNM stage (p=0.01981) and ER expression (p=0.4689). RelB expressions in TNBC cell lines were higher than that of hormone receptor positive MCF-7 cells. In vitro studies showed that RelB deletion promoted apoptosis and suppressed breast cancer cell survival, migration and invasion by decreasing snail, vimentin and MMP1. RelB deletion inhibited cell cycle progression and G1/S transition by upregulating p21 and p27 expression. In vivo studies showed that 231-RelB-KO cells completely impaired tumor formation in xenograft models and lung metastasis model in nude mice. Conclusion: RelB is aberrant constitutive expressed in clinical specimens and cell lines of breast cancer, especially in TNBC. RelB regulates malignant phenotypes of breast cancer, including cell survival, migration and invasion, as well as apoptosis and the cell cycle. Moreover, RelB can induce MMP1, which facilitates the invasion of tumor. Collectively, our findings highlight that RelB might serve as a therapeutic target for triple negative breast cancer. Citation Format: Wang M, Tang J. RelB facilitates cell migration and invasion in breast cancer via MMP1 upregulation [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-09-03.