αB-Crystallin: A Novel Regulator of Breast Cancer Metastasis to the Brain

Abstract

Purpose: Basal-like breast tumors are typically (ER/PR/HER2) triple-negative and are associated with a high incidence of brain metastases and poor clinical outcomes. The molecular chaperone aB-crystallin is predominantly expressed in triple-negative breast cancer (TNBC) and contributes to an aggressive tumor phenotype in preclinical models. We investigated the potential role of aB-crystallin in brain metastasis in TNBCs.Experimental Design: aB-crystallin expression in primary breast carcinomas and brain metastases was analyzed by immunohistochemistry among patients with breast cancer with brain metastases. aB-crystallin was overexpressed or silenced in two different TNBC cell lines. The effects on cell adhesion to human brain microvascular endothelial cells (HBMEC) or extracellular matrix proteins, transendothelial migration, and transmigration across a HBMEC/astrocyte coculture blood-brain barrier (BBB) model were examined. In addition, the effects of overexpressing or silencing aB-crystallin on brain metastasis in vivo were investigated using orthotopic TNBC models.Results: In a cohort of women with breast cancer brain metastasis, aB-crystallin expression in primary breast carcinomas was associated with poor overall survival and poor survival after brain metastasis, even among patients with TNBC. Stable overexpression of aB-crystallin in TNBC cells enhanced adhesion to HBMECs, transendothelial migration, and BBB transmigration in vitro, whereas silencing aB-crystallin inhibited these events. aB-crystallin promoted adhesion of TNBC cells to HBMECs, at least in part, through an a3b1 integrin-dependent mechanism. aB-crystallin overexpression promoted brain metastasis, whereas silencing aB-crystallin inhibited brain metastasis in orthotopic TNBC models.Conclusion: aB-crystallin is a novel regulator of brain metastasis in TNBC and represents a potential biomarker and drug target for this aggressive disease. Clin Cancer Res; 1-12. Ó2013 AACR.

NanoFlares for the detection, isolation, and culture of live tumor cells from human blood

“…All animal experiments were approved by the Institutional Animal Care and Use Committee at the University of Wisconsin-Madison. mCherry-labeled MDA-MB-231 cells (2.5 × 10 5 ) were resuspended in 100% Matrigel (BD Bioscience) and injected intraductally into the fourth mammary glands of 4-to 5-wk-old female immunodeficient NOD scid IL2 receptor γ chain knockout (NSG) mice (n = 12; The Jackson Laboratory) as described previously (26). Control mice were not injected with tumor cells (n = 12).…”

“…To determine whether NanoFlares can detect CTCs in a murine model, we used an orthotopic model of triple-negative breast cancer (TNBC) with widespread metastases to several organs (26). Blood was obtained 6.5 wk after tumor-cell inoculation and was treated with Vimentin, Fibronectin, or nontargeting Scrambled Control NanoFlares, or PBS of an equivalent volume for 6 h. Samples were processed to remove red blood cells and CD45 + and ter119 + cells and then analyzed for mCherry (Cy3 channel) and NanoFlare (Cy5 channel) fluorescence using flow cytometry (Fig.…”

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

“…Corresponding results revealed the breast tumours that linked to BM do frequently express cytokeratin-5 (P < 0.05), prominin-1 (P < 0.05), nestin (P < 0.1), smooth muscle actin (P < 0.1) being more often ER and PR negative (P < 0.05). The heat shock protein αB-crystallin (CRYAB) is frequently expressed in TN subtype of breast tumours being associated with early occurrence of BM and poor prognosis for the affected patients [32]. In an independent study utilising the data of 855 BC patients, the CRYAB expression detected in the tumour tissue was proposed to be an independent predictor for BM as the first distant metastatic site (HR = 1.2, 95% CI 1.0-1.4, P = 0.021) [33].…”

Blood-brain Barrier Remodeling during Brain Metastasis Formation

“…The binding of αVβ3 integrin to platelet endothelial cell adhesion molecule 1 (PECAM1) has been proposed to be involved in endothelial junction disruption (25). αB-crystallin, a molecular chaperone commonly expressed in aggressive tumors, has also been associated with increased adhesion of breast cancer cells to brain endothelium via α3β1 integrin-dependent mechanism (47). Recently, another mechanism of BBB breakdown, involving cancer-derived extracellular vesicles, was proposed.…”