Activation of Notch Signaling in a Xenograft Model of Brain Metastasis

Abstract

Purpose: The potential of metastasis can be predicted from clinical features like tumor size, histologic grade, and gene expression patterns. We examined the whole-genome transcriptomic profile of a xenograft model of breast cancer to understand the characteristics of brain metastasis. Experimental Design: Variants of the MDA-MB-435 cell were established from experimental brain metastases. The LvBr2 variant was isolated from lesions in a mouse injected in the left ventricle of the heart, and these cells were used for two cycles of injection into the internal carotid artery and selection of brain lesions, resulting in the Br4 variant. To characterize the different metastatic variants, we examined the gene expression profile of MDA-MB-435, LvBr2, and Br4 cells using microarrays. Results: We could identify 2,016 differentially expressed genes in Br4 by using the F test. Various metastasis-related genes and a number of genes related to angiogenesis, migration, tumorigenesis, and cell cycle were differentially expressed by the Br4 cells. Notably, the Notch signaling pathway was activated in Br4, with increased Jag2 mRNA, activated Notch intracellular domain, and Notch intracellular domain/CLS promoter-luciferase activity. Br4 cells were more migratory and invasive than MDA-MB-435 cells in collagen and Matrigel Transwell assays, and the migration and invasion of Br4 cells were significantly inhibited by inactivation of Notch signaling using DAPT, a g-secretase inhibitor, and RNA interference^mediated knockdown of Jagged 2 and Notch1. Conclusions: Taken together, these results suggest that we have isolated variants of a human cancer cell line with enhanced brain metastatic properties, and the activation of Notch signaling might play a crucial role in brain metastasis.

MicroRNA-146a Suppresses Metastatic Activity in Brain Metastasis

“…Increased expression of β-catenin by miR-146a was also found in Br4 cells which were isolated through two cycles of injection of LvBr2 cells into the internal carotid artery ( Supplementary Fig. 2D) (Nam et al, 2008). To evaluate whether miR-146a influenced β-catenin expression through the β-catenin 3′UTR, we used a reporter vector that expressed a heterologous GFP mRNA carrying the β-catenin 3′UTR.…”

“…Brain-trophic metastatic LvBr2 cells showed higher metastatic activity than parent MDA-MB-435 cells MDA-MB-435 cells were reported to form brain metastasis by injection into the left ventricle (LV) of heart or the internal carotid artery (ICA) (Nam et al, 2008;Price et al, 1990). To investigate the role of miRNA in brain metastasis, MDA-MB-435-LvBr cells were isolated from brain metastasis cells after serial LV injection of parent MDA-MB-435 cells (LvBr1 cells were obtained from the first cycle and LvBr2 cells from the second cycle).…”

“…Xenograft model for brain metastasis and miRNA microarray Brain-trophic metastatic MDA-MB-435 cells were isolated previously after serial injection of MDA-MB-435 cells through the left ventricle (LV) of heart (Nam et al, 2008). We termed these brain-trophic metastatic cells as MDA-MB-435-LvBr1 (LvBr1, first cycle) and MDA-MB-435-LvBr2 (LvBr2, second cycle).…”

Mystery of the brain metastatic disease in breast cancer patients: improved patient stratification, disease prediction and targeted prevention on the horizon?

“…Further, the overexpression of HER3 receptor and subsequent activation of MAPK signalling pathway were found to be preferentially activated in the brain metastases of BC patients [36,37]. Preclinical studies demonstrated the stem cell-specific signalling by the Wnt and Notch pathways to be associated with the development of BM [38,39]. Angiogenic factors-the vascular endothelial growth factor (VEGF), angiopoietin-2 and chemokine receptor type 4 (CXCR-4)-have been identified as the specific drivers of BM developmental process [40][41][42][43][44][45].…”

Notch-4 contributes to the metastasis of salivary adenoid cystic carcinoma

“…Nam et al reported that the overexpression of Notch-1 and its ligands (DLL-1 and Jag-1) is critical for the survival and proliferation of glioma cells, and the inactivation of Notch signaling can significantly inhibit the migration and invasion of Br4 cells (26). Leong et al observed that Notch-4 activation in human dermal microvascular endothelial cells inhibited endothelial cell sprouting and the vascular endothelial growth factor-induced angiogenesis in the chick chorioallantoic membrane in vivo (27).…”