Notch-Mediated Tumor-Stroma-Inflammation Networks Promote Invasive Properties and CXCL8 Expression in Triple-Negative Breast Cancer

Abstract

Stromal cells and pro-inflammatory cytokines play key roles in promoting the aggressiveness of triple-negative breast cancers (TNBC; Basal/Basal-like). In our previous study we demonstrated that stimulation of TNBC and mesenchymal stem cells (MSCs) co-cultures by the pro-inflammatory cytokine tumor necrosis factor α (TNFα) has led to increased metastasis-related properties in vitro and in vivo . In this context, elevated release of the pro-metastatic chemokines CXCL8 (IL-8) and CCL5 (RANTES) was noted in TNFα- and interleukin-1β (IL-1β)-stimulated TNBC:MSC co-cultures; the process was partly (CXCL8) and entirely (CCL5) dependent on physical contacts between the two cell types. Here, we demonstrate that DAPT, inhibitor of γ-secretase that participates in activation of Notch receptors, inhibited the migration and invasion of TNBC cells that were grown in “Contact” co-cultures with MSCs or with patient-derived cancer-associated fibroblasts (CAFs), in the presence of TNFα. DAPT also inhibited the contact-dependent induction of CXCL8, but not of CCL5, in TNFα- and IL-1β-stimulated TNBC:MSC/CAF co-cultures; some level of heterogeneity between the responses of different TNBC cell lines was noted, with MDA-MB-231:MSC/CAF co-cultures being the most sensitive to DAPT. Patient dataset studies comparing basal tumors to luminal-A tumors, and mRNA analyses of Notch receptors in TNBC and luminal-A cells pointed at Notch1 as possible mediator of CXCL8 increase in TNFα-stimulated TNBC:stroma “Contact” co-cultures. Accordingly, down-regulation of Notch1 in TNBC cells by siRNA has substantially reduced the contact-dependent elevation in CXCL8 in TNFα- and also in IL-1β-stimulated TNBC:MSC “Contact” co-cultures. Then, studies in which CXCL8 or p65 (NF-κB pathway) were down-regulated (siRNAs; CRISPR/Cas9) in TNBC cells and/or MSCs, indicated that upon TNFα stimulation of “Contact” co-cultures, p65 was activated and led to CXCL8 production mainly in TNBC cells. Moreover, our findings indicated that when tumor cells interacted with stromal cells in the presence of pro-inflammatory stimuli, TNFα-induced p65 activation has led to elevated Notch1 expression and activation, which then gave rise to elevated production of CXCL8. Overall, tumor:stroma interactions set the stage for Notch1 activation by pro-inflammatory signals, leading to CXCL8 induction and consequently to pro-metastatic activities. These observations may have important clinical implications in designing novel therapy combinations in TNBC.

DNER promotes epithelial–mesenchymal transition and prevents chemosensitivity through the Wnt/β-catenin pathway in breast cancer

“…DNER, atypical ligand of the Notch1 pathway, was initially found to be highly expressed in Purkinje neurons and plays a key role in cerebellar development 25,26 . Furthermore, the Notch pathway is involved in carcinogenesis and promotes the proliferation and malignant progression of various tumours [27][28][29] . Until now, the role of DNER in cancer has remained controversial, and the function of DNER may vary according to cell type.…”

The influence of microenvironment on tumor immunotherapy

“…High levels of CAF‐secreted IL‐6 induced tumor immunosuppression by recruiting MDSCs and upregulating PD‐L1 expression, impairing the efficacy of anti‐PD‐L1 immunotherapy against hepatocellular carcinoma (HCC), and IL‐6 blockade increased the efficacy of PD‐L1 treatment . Interestingly, tumor‐associated stromal cells/CAFs themselves also expressed PD‐L1 to suppress CD8 + antitumor immune responses in response to the inflammatory secretome from human colon cancer cells, and pre‐inflammatory cytokine TNFα and IL‐1β induced CXCL8/CCL5 secretion in the co‐culture of CAFs and triple negative breast cancers , suggesting that the inflammation also regulates the immunological response of CAFs/stromal cells in the TME. In addition, CAFs in HCC regulate the survival and activation of neutrophils through the IL‐6–signal transducer and activator of transcription (STAT) 3–PD‐L1 signaling pathway and consequently affect the function of T cells .…”

Exploring the Regulation Mechanism of Xihuang Pill, Olibanum and β-Boswellic Acid on the Biomolecular Network of Triple-Negative Breast Cancer Based on Transcriptomics and Chemical Informatics Methodology

“…Recent studies have shown that the cell surface adhesion receptor CD44 is a key positive regulator of PD-L1 expression in TNBC and non-small cell lung cancer (NSCLC) (Kong et al, 2019). The Notch-mediated tumorinterstitial-inflammatory network promotes TNBC invasiveness and CXCL8 expression (Liubomirski et al, 2019). High expression of UBE2C is a potential factor for poor prognosis of TNBC.…”