Update on the Role of NFκB in Promoting Aggressive Phenotypes of Estrogen Receptor-Positive Breast Cancer

Therapeutic implications of the interplay between interferons and ER in breast cancer

The involvement of interferons (IFNs) in various diseases, including breast cancer, has sparked controversy due to their diverse roles in immunity and significant impact on pathological mechanisms. In the context of breast cancer, the heightened expression of endogenous IFNs has been linked to anti-tumor activity and a favorable prognosis for patients. Within the tumor tissue and microenvironment, IFNs initiate a cascade of molecular events involving numerous factors, which can lead to either cooperative or repressive interactions. The specific functions of IFNs in breast cancer vary depending on the two major disease phenotypes: hormone dependent (or responsive) and hormone independent (or unresponsive) breast cancer. Hormone dependence is determined by the presence of estrogen receptors (ERs). The interplay between the IFN and ER signaling pathways, and the involvement of intermediate factors such as NFκB, are areas that have been somewhat under-researched, but that hold potential importance for the understanding and treatment of breast cancer. This review aims to provide a comprehensive overview of the actions of IFNs in breast cancer, particularly in relation to the different breast cancer phenotypes and the significance of comprehending the underlying mechanisms. Furthermore, the use of IFN-based therapies in cancer treatment remains a topic of debate and has not yet gained widespread acceptance. However, emerging discoveries may redirect focus towards the potential of IFN-based therapies.

NF-κB in Cell Deaths, Therapeutic Resistance and Nanotherapy of Tumors: Recent Advances

The transcription factor nuclear factor-κB (NF-κB) plays a complicated role in multiple tumors. Mounting evidence demonstrates that NF-κB activation supports tumorigenesis and development by enhancing cell proliferation, invasion, and metastasis, preventing cell death, facilitating angiogenesis, regulating tumor immune microenvironment and metabolism, and inducing therapeutic resistance. Notably, NF-κB functions as a double-edged sword exerting positive or negative influences on cancers. In this review, we summarize and discuss recent research on the regulation of NF-κB in cancer cell deaths, therapy resistance, and NF-κB-based nano delivery systems.

A Tumor Microenvironment-Driven Network Regulated by STAT3 and p65 Negatively Controls the Enrichment of Cancer Stem Cells in Human HR+/HER2- Breast Cancer

Hormone receptor-positive and HER2-negative (HR+/HER2-; luminal A) tumors are prevalent in breast cancer. Our past studies demonstrated that "TME Stimulation" (estrogen + TNFα + EGF, representing three arms of the tumor microenvironment, TME) has enriched metastasis-forming cancer stem cells (CSCs) in HR+/HER2- human breast cancer cells. Here, following information obtained by RNAseq analyses of TME-stimulated CSCs and Non-CSCs, we found that TME Stimulation has induced the activation of S727-STAT3, Y705-STAT3, STAT1 and p65. Upon TME Stimulation, stattic (STAT3 inhibitor) usage demonstrated that Y705-STAT3 activation negatively controlled CSC enrichment and epithelial-to-mesenchymal transition (EMT) traits, while inducing CXCL8 (IL-8) and PD-L1 expression. However, STAT3 knock-down (siSTAT3) had no effect on these functions; in terms of CSC enrichment, p65 had down-regulatory roles that compensated for the loss of an entire STAT3 protein. Y705-STAT3 and p65 acted additively in reducing CSC enrichment, and Y705A-STAT3 variant + sip65 has enriched chemo-resistant CSCs. Clinical data analyses revealed an inverse correlation between Y705-STAT3 + p65 phosphorylation and CSC signature in luminal A patients, and connection to improved disease course. Overall, we find regulatory roles for Y705-STAT3 and p65 in TME-stimulated HR+/HER2- tumors, with the ability to limit CSC enrichment. These findings raise concerns about using inhibitors of STAT3 and p65 as therapeutic strategies in the clinic.

A Multiomic Analysis Reveals How Breast Cancers Disseminated to the Bone Marrow Acquire Aggressive Phenotypes through Tumor-Stroma Tunnels

Estrogen receptor-positive (ER+) breast cancer commonly disseminates to bone marrow, where interactions with mesenchymal stromal cells (MSCs) shape disease trajectory. We modeled these interactions with tumor-MSC co-cultures and used an integrated transcriptome-proteome-network- analyses workflow to identify a comprehensive catalog of contact-induced changes. Induced genes and proteins in cancer cells, some borrowed and others tumor-intrinsic, were not recapitulated merely by conditioned media from MSCs. Protein-protein interaction networks revealed the rich connectome between 'borrowed' and 'intrinsic' components. Bioinformatic approaches prioritized one of the 'borrowed' components, CCDC88A /GIV, a multi-modular metastasis-related protein which has recently been implicated in driving one of the hallmarks of cancers, i.e., growth signaling autonomy. MSCs transferred GIV protein to ER+ breast cancer cells (that lack GIV) through tunnelling nanotubes via connexin (Cx)43-facilitated intercellular transport. Reinstating GIV alone in GIV-negative breast cancer cells reproduced ∼20% of both the 'borrowed' and the 'intrinsic' gene induction patterns from contact co-cultures; conferred resistance to anti-estrogen drugs; and enhanced tumor dissemination. Findings provide a multiomic insight into MSC→tumor cell intercellular transport and validate how transport of one such candidate, GIV, from the haves (MSCs) to have-nots (ER+ breast cancer) orchestrates aggressive disease states.

Nogo-B receptor increases glycolysis and the paclitaxel resistance of estrogen receptor-positive breast cancer via the HIF-1α-dependent pathway

Chemotherapy can improve the prognosis and overall survival of breast cancer patients, but chemoresistance continues a major problem in clinical. Most breast cancer is estrogen receptor (ER) positive but responds less to neoadjuvant or adjuvant chemotherapy than ER-negative breast cancer. The Nogo-B receptor (NgBR) increases the chemoresistance of ER-positive breast cancer by facilitating oncogene signaling pathways. Here, we further investigated the potential role of NgBR as a novel target to overcome glycolysis-dependent paclitaxel resistance in ER-positive breast cancer. NgBR knockdown inhibited glycolysis and promoted paclitaxel-induced apoptosis by attenuating HIF-1α expression in ER-positive breast cancer cells via NgBR-mediated estrogen receptor alpha (ERα)/hypoxia-inducible factor-1 alpha (HIF-1α) and nuclear factor-kappa B subunit (NF-κB)/HIF-1α signaling pathways. A ChIP assay further confirmed that NgBR overexpression not only facilitates ERα binding to HIF-1α and GLUT1 genes but also promotes HIF-1α binding to GLUT1, HK2, and LDHA genes, which further promotes glycolysis and induces paclitaxel resistance. In conclusion, our study suggests that NgBR expression is essential for maintaining the metabolism and paclitaxel resistance of ER-positive breast cancer, and the NgBR can be a new therapeutic target for improving chemoresistance in ER-positive breast cancer.

Selective pressure of endocrine therapy activates the integrated stress response through NFκB signaling in a subpopulation of ER positive breast cancer cells

Background

While estrogen receptor (ER) positive breast tumors generally respond well to endocrine therapy (ET), up to 40% of patients will experience relapse, either while on endocrine therapy or after ET is completed. We previously demonstrated that the selective pressure of tamoxifen activates the NFκB pathway in ER + patient tumors, breast cancer cell lines, and breast cancer xenograft tumors, and that this activation allows for survival of a subpopulation of NFκB + cells that contribute to cell regrowth and tumor relapse after ET withdrawal. However, the mechanisms contributing to the expansion of an NFκB + cell population on ET are unknown.

Methods

Here, we utilized single-cell RNA sequencing and bioinformatics approaches to characterize the NFκB + cell population and its clinical relevance. Follow-up studies were conducted to validate our findings and assess the function of the integrated stress response pathway in breast cancer cell lines and patient-derived models.

Results

We found that the NFκB + population that arises in response to ET is a preexisting population is enriched under the selective pressure of ET. Based on the preexisting NFκB + cell population, we developed a gene signature and found that it is predictive of tumor relapse when expressed in primary ER + tumors and is retained in metastatic cell populations. Moreover, we identified that the integrated stress response (ISR), as indicated by increased phosphorylation of eIF2α, occurs in response to ET and contributes to clonogenic growth under the selective pressure of ET.

Conclusions

Taken together, our findings suggest that a cell population with active NFκB and ISR signaling can survive and expand under the selective pressure of ET and that targeting this population may be a viable therapeutic strategy to improve patient outcome by eliminating cells that survive ET. Understanding the mechanisms by which breast cancer cells survive the selective pressure of ET may improve relapse rates and overall outcome for patients with ER + breast tumors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-022-01515-1.

Influence of Estrogen Treatment on ESR1+ and ESR1- Cells in ER+ Breast Cancer: Insights from Single-Cell Analysis of Patient-Derived Xenograft Models

Simple Summary

The benefit of endocrine therapy is normally observed for cancers with 10% or more of cells positive for ER expression. We compared the gene expression profiles in both ESR1⁺ and ESR1^– cells in ER⁺ tumors following estrogen treatment. Our single-cell RNA sequencing analysis of estrogen-stimulated (SC31) and estrogen-suppressed (GS3) patient-derived xenograft models offered an unprecedented opportunity to address the molecular and functional differences between ESR1⁺ and ESR1^– cells. While estrogen should activate ERα and stimulate ESR1⁺ cells, our findings regarding ESR1^– cells were important, indicating that the proliferation of ESR1^– cells in ER⁺ cancer is also influenced by estrogen. Another valuable finding from our studies was that estrogen also upregulated a tumor-suppressor gene, IL-24, only in GS3. Estrogen increased the percentage of cells expressing IL-24, associated with the estrogen-dependent inhibition of GS3 tumor growth.

Abstract

A 100% ER positivity is not required for an endocrine therapy response. Furthermore, while estrogen typically promotes the progression of hormone-dependent breast cancer via the activation of estrogen receptor (ER)-α, estrogen-induced tumor suppression in ER⁺ breast cancer has been clinically observed. With the success in establishing estrogen-stimulated (SC31) and estrogen-suppressed (GS3) patient-derived xenograft (PDX) models, single-cell RNA sequencing analysis was performed to determine the impact of estrogen on ESR1⁺ and ESR1^– tumor cells. We found that 17β-estradiol (E2)-induced suppression of GS3 transpired through wild-type and unamplified ERα. E2 upregulated the expression of estrogen-dependent genes in both SC31 and GS3; however, E2 induced cell cycle advance in SC31, while it resulted in cell cycle arrest in GS3. Importantly, these gene expression changes occurred in both ESR1⁺ and ESR1^– cells within the same breast tumors, demonstrating for the first time a differential effect of estrogen on ESR1^– cells. E2 also upregulated a tumor-suppressor gene, IL-24, in GS3. The apoptosis gene set was upregulated and the G2M checkpoint gene set was downregulated in most IL-24⁺ cells after E2 treatment. In summary, estrogen affected pathologically defined ER⁺ tumors differently, influencing both ESR1⁺ and ESR1^– cells. Our results also suggest IL-24 to be a potential marker of estrogen-suppressed tumors.

Olfactory receptor 5B21 drives breast cancer metastasis

Olfactory receptors (ORs), responsible for the sense of smell, play an essential role in various physiological processes outside the nasal epithelium, including cancer. In breast cancer, however, the expression and function of ORs remain understudied. We examined the significance of OR transcript abundance in primary and metastatic breast cancer to the brain, bone, and lung. Although 20 OR transcripts were differentially expressed in distant metastases, OR5B21 displayed an increased transcript abundance in all three metastatic sites compared with the primary tumor. Knockdown of OR5B21 significantly decreased the invasion and migration of breast cancer cells as well as metastasis to different organs especially the brain, whereas increasing of OR5B21 transcript abundance had the opposite effect. Mechanistically, OR5B21 expression was associated with epithelial to mesenchymal transition through the STAT3/NF-κB/CEBPβ signaling axis. We propose OR5B21 (and potentially other ORs) as a novel oncogene contributing to breast cancer metastasis and a potential target for adjuvant therapy.

Methylparaben-induced regulation of estrogenic signaling in human neutrophils

Parabens, including the most common methylparaben (MeP), are popular preservatives, which possess estrogenic activity. The aims of this study were to assess the impact of MeP on estrogen receptors (ERs) and/or NF-κB-dependent generation of IL-8 and production of nitric oxide (NO), and also to verify the hypothesis about the crosstalk of ERs with NF-κB in xenoestrogen-exposed neutrophils. Human neutrophils were incubated for 20-h with MeP (0.06 μM) and/or ER antagonist (1 μM) and/or NF-κB inhibitor (100 μM). After the isolation of cell lysates and cytoplasmic and nuclear fraction, the expression of ERα, ERβ, p-IKKα/β, p65 NF-κB, and inducible nitric oxide synthase (iNOS) was measured by Western blot analysis, The concentration of NO was evaluated by Griess reaction, and that of IL-8 was measured by ELISA. The results showed that MeP modulated the expression of ERα, but not ERβ. Exposure to paraben activated iKKα/β-dependent NF-κB pathway, but translocation of p65 NF-κB into the cell nucleus was inhibited by ERs. MeP also decreased the iNOS-dependent production of NO, but did not influence the secretion of IL-8 by neutrophils. The study indicates that MeP may affect the functioning of human neutrophils by modulating intracellular signal transduction pathways, including ERs and NF-κB pathway.

Epsin 3 potentiates the NF‑κB signaling pathway to regulate apoptosis in breast cancer

Endocrine drug resistance is common in some patients with estrogen receptor (ER)-positive breast cancer, so it is necessary to identify potential therapeutic targets. The aim of the present study was to investigate the regulatory effect and mechanism of epsin 3 (EPN3) expression level changes on the proliferation and apoptosis of ER-positive breast cancer. Online GEPIA was used to analyze the expression level of EPN3 in breast cancer. The online Kaplan-Meier plotter tool was used to analyze the relationship between EPN3 expression and the prognosis of patients with breast cancer. Reverse transcription-quantitative PCR, immunohistochemistry and western blotting were performed to detect the mRNA and protein expression levels of EPN3 in breast cancer tissues and cells. A lentiviral infection system was used to knockdown the expression of EPN3 in breast cancer cell lines. Cell Counting Kit-8 and flow cytometry assays were conducted to detect the effect of EPN3 knockdown on breast cancer cell proliferation and apoptosis. Western blotting was used to detect the regulation of EPN3 expression on NF-κB, and immunofluorescence was performed to detect the effect of EPN3 expression on NF-κB nuclear translocation. The results demonstrated that the expression level of EPN3 in breast cancer tissues was higher compared with that in adjacent tissues (P<0.05). The expression level of EPN3 in the ER-positive breast cancer cell line, MCF7, was higher compared with that in the other cell lines (MCF10A, ZR75-1, MDA-MB-231, BT549 and SK-BR-3). After knocking down the expression of EPN3 in MCF7 cells, the proliferative ability of the cells was decreased, and the apoptosis rate was increased (P<0.05). After EPN3 knockdown in MCF7 cells, the phosphorylation of NF-κB was decreased (P<0.05), and the nuclear translocation signal was weakened. Thus, it was suggested that EPN3 promoted cell proliferation and inhibited cell apoptosis by regulating the NF-κB signaling pathway in ER-positive breast cancer.

Endogenous and Therapeutic Estrogens: Maestro Conductors of the Microenvironment of ER+ Breast Cancers

Estrogen receptor alpha (ERα) marks heterogeneous breast cancers which display a repertoire of somatic genomic mutations and an immune environment that differs from other breast cancer subtypes. These cancers also exhibit distinct biological behaviors; despite an overall better prognosis than HER2+ or triple negative breast cancers, disseminated dormant cells can lead to disease recurrence decades after the initial diagnosis and treatment. Estrogen is the best studied driver of these cancers, and antagonism or reduction of estrogen activity is the cornerstone of therapeutic approaches. In addition to reducing proliferation of ERα+ cancer cells, these treatments also alter signals to multiple other target cells in the environment, including immune cell subpopulations, cancer-associated fibroblasts, and endothelial cells via several distinct estrogen receptors. In this review, we update progress in our understanding of the stromal cells populating the microenvironments of primary and metastatic ER+ tumors, the effects of estrogen on tumor and stromal cells to modulate immune activity and the extracellular matrix, and net outcomes in experimental and clinical studies. We highlight new approaches that will illuminate the unique biology of these cancers, provide the foundation for developing new treatment and prevention strategies, and reduce mortality of this disease.