The Epigenetics of Triple-Negative and Basal-Like Breast Cancer: Current Knowledge

Apigenin and its combination with Vorinostat induces apoptotic-mediated cell death in TNBC by modulating the epigenetic and apoptotic regulators and related miRNAs

Triple-negative breast cancer (TNBC) is a metastatic disease and a formidable treatment challenge as it does not respond to existing therapies. Epigenetic regulators play a crucial role in the progression and metastasis by modulating the expression of anti-apoptotic, pro-apoptotic markers and related miRNAs in TNBC cells. We have investigated the anti-TNBC potential of dietary flavonoid 'Apigenin' and its combination with Vorinostat on MDA-MB-231 cells. At Apigenin generated ROS, inhibited cell migration, arrested the cell cycle at subG0/G1 phases, and induced apoptotic-mediated cell death. Apigenin reduced the expression of the class-I HDACs at the transcriptomic and proteomic levels. In the immunoblotting study, Apigenin has upregulated pro-apoptotic markers and downregulated anti-apoptotic proteins. Apigenin inhibited the enzymatic activity of HDAC/DNMT and increased HAT activity. Apigenin has manifested its effect on miRNA expression by upregulating the tumor-suppressor miR-200b and downregulation oncomiR-21. Combination study reduced the growth of TNBC cells synergistically by modulating the expression of epigenetic and apoptotic regulators. Molecular docking and MD simulations explored the mechanism of catalytic inhibition of HDAC1 and HDAC3 and supported the in-vitro studies. The overall studies demonstrated an anti-TNBC potential of Apigenin and may help to design an effective strategy to treat metastatic phenotype of TNBC.

A deep learning based holistic diagnosis system for immunohistochemistry interpretation and molecular subtyping

BACKGROUND

Breast cancer in different molecular subtypes, which is determined by the overexpression rates of human epidermal growth factor receptor 2 (HER2), estrogen receptor (ER), progesterone receptor (PR), and Ki67, exhibit distinct symptom characteristics and sensitivity to different treatment. The immunohistochemical method, one of the most common detecting tools for tumour markers, is heavily relied on artificial judgment and in clinical practice, with an inherent limitation in interpreting stability and operating efficiency. Here, a holistic intelligent breast tumour diagnosis system has been developed for tumour-markeromic analysis, combining the automatic interpretation and clinical suggestion.

METHODS

The holistic intelligent breast tumour diagnosis system included two main modules. The interpreting modules were constructed based on convolutional neural network, for comprehensively extracting and analyzing the multi-features of immunostaining. Referring to the clinical classification criteria, the interpreting results were encoded in a low-dimensional feature representation in the subtyping module, to efficiently output a holistic detecting result of the critical tumour-markeromic with diagnosis suggestions on molecular subtypes.

RESULTS

The overexpression rates of HER2, ER, PR, and Ki67, as well as an effective determination of molecular subtypes were successfully obtained by this diagnosis system, with an average sensitivity of 97.6 % and an average specificity of 96.1 %, among those, the sensitivity and specificity for interpreting HER2 were up to 99.8 % and 96.9 %.

CONCLUSION

The holistic intelligent breast tumour diagnosis system shows improved performance in the interpretation of immunohistochemical images over pathologist-level, which can be expected to overcome the limitations of conventional manual interpretation in efficiency, precision, and repeatability.

UCHL1 contributes to insensitivity to endocrine therapy in triple-negative breast cancer by deubiquitinating and stabilizing KLF5

BACKGROUND

Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) is a deubiquitinating enzyme that regulates ERα expression in triple-negative cancer (TNBC). This study aimed to explore the deubiquitination substrates of UCHL1 related to endocrine therapeutic responses and the mechanisms of UCHL1 dysregulation in TNBC.

METHODS

Bioinformatics analysis was conducted using online open databases. TNBC representative MDA-MB-468 and SUM149 cells were used for in vitro and in-vivo studies. Co-immunoprecipitation was used to explore the interaction between UCHL1 and KLF5 and UCHL1-mediated KIF5 deubiquitination. CCK-8, colony formation and animal studies were performed to assess endocrine therapy responses. The regulatory effect of TET1/3 on UCHL1 promoter methylation and transcription was performed by Bisulfite sequencing PCR and ChIP-qPCR.

RESULTS

UCHL1 interacts with KLF5 and stabilizes KLF5 by reducing its polyubiquitination and proteasomal degradation. The UCHL1-KLF5 axis collaboratively upregulates EGFR expression while downregulating ESR1 expression at both mRNA and protein levels in TNBC. UCHL1 knockdown slows the proliferation of TNBC cells and sensitizes the tumor cells to Tamoxifen and Fulvestrant. KLF5 overexpression partially reverses these trends. Both TET1 and TET3 can bind to the UCHL1 promoter region, reducing methylation of associated CpG sites and enhancing UCHL1 transcription in TNBC cell lines. Additionally, TET1 and TET3 elevates KLF5 protein level in a UCHL1-dependent manner.

CONCLUSION

UCHL1 plays a pivotal role in TNBC by deubiquitinating and stabilizing KLF5, contributing to endocrine therapy resistance. TET1 and TET3 promote UCHL1 transcription through promoter demethylation and maintain KLF5 protein level in a UCHL1-dependent manner, implying their potential as therapeutic targets in TNBC.

Synergistic effects of combined cisplatin and Clinacanthus nutans extract on triple negative breast cancer cells

Objective

Triple negative breast cancer (TNBC) is the most invasive breast cancer subtype enriched with cancer stem cells. TNBCs do not express estrogen, progesterone, or human epidermal growth factor receptor 2 (HER2) receptors, making them difficult to be targeted by existing chemotherapy treatments. In this study, we attempted to identify the effects of combined cisplatin and Clinacanthus nutans treatment on MDA-MD-231 and MDA-MB-468 breast cancer cells, which represent TNBC subtypes.

Methods

The phytochemical fingerprint of C. nutans ethanolic leaf extract was evaluated by LC-MS/MS analysis. We investigated the effects of cisplatin (0-15.23 μg/mL), C. nutans (0-50 μg/mL), and a combination of cisplatin (3.05 μg/mL) and C. nutans (0-50 μg/mL), on cell viability, proliferation, apoptosis, invasion, mRNA expression in cancer stem cells (CD49f, KLF4), and differentiation markers (TUBA1A, KRT18) in TNBC cells. In addition, we also studied the interaction between cisplatin and C. nutans.

Results

Derivatives of fatty acids, carboxylic acid ester, and glycosides, were identified as the major bioactive compounds with potential anticancer properties in C. nutans leaf extract. Reductions in cell viability (0-78%) and proliferation (2-77%), as well as a synergistic anticancer effect, were identified in TNBC cells when treated with a combination of cisplatin and C. nutans. Furthermore, apoptotic induction via increased caspase-3/7 activity (MDA-MB-231: 2.73-fold; MDA-MB-468: 3.53-fold), and a reduction in cell invasion capacity to 36%, were detected in TNBC cells when compared to single cisplatin and C. nutans treatments. At the mRNA level, cisplatin and C. nutans differentially regulated specific genes that are responsible for proliferation and differentiation.

Conclusion

Our findings demonstrate that the combination of cisplatin and C. nutans represents a potential treatment for TNBC.

Targeting redox regulation and autophagy systems in cancer stem cells

Cancer is a dysregulated cellular level pathological condition that results in tumor formation followed by metastasis. In the heterogeneous tumor architecture, cancer stem cells (CSCs) are essential to push forward the progression of tumors due to their strong pro-tumor properties such as stemness, self-renewal, plasticity, metastasis, and being poorly responsive to radiotherapy and chemotherapeutic agents. Cancer stem cells have the ability to withstand various stress pressures by modulating transcriptional and translational mechanisms, and adaptable metabolic changes. Owing to CSCs heterogeneity and plasticity, these cells display varied metabolic and redox profiles across different types of cancers. It has been established that there is a disparity in the levels of Reactive Oxygen Species (ROS) generated in CSCs vs Non-CSC and these differential levels are detected across different tumors. CSCs have unique metabolic demands and are known to change plasticity during metastasis by passing through the interchangeable epithelial and mesenchymal-like phenotypes. During the metastatic process, tumor cells undergo epithelial to mesenchymal transition (EMT) thus attaining invasive properties while leaving the primary tumor site, similarly during the course of circulation and extravasation at a distant organ, these cells regain their epithelial characteristics through Mesenchymal to Epithelial Transition (MET) to initiate micrometastasis. It has been evidenced that levels of Reactive Oxygen Species (ROS) and associated metabolic activities vary between the epithelial and mesenchymal states of CSCs. Similarly, the levels of oxidative and metabolic states were observed to get altered in CSCs post-drug treatments. As oxidative and metabolic changes guide the onset of autophagy in cells, its role in self-renewal, quiescence, proliferation and response to drug treatment is well established. This review will highlight the molecular mechanisms useful for expanding therapeutic strategies based on modulating redox regulation and autophagy activation to targets. Specifically, we will account for the mounting data that focus on the role of ROS generated by different metabolic pathways and autophagy regulation in eradicating stem-like cells hereafter referred to as cancer stem cells (CSCs).

Drug repurposing for Basal breast cancer subpopulations using modular network signatures

Breast cancer is characterized as being a heterogeneous pathology with a broad phenotype variability. Breast cancer subtypes have been developed in order to capture some of this heterogeneity. Each of these breast cancer subtypes, in turns retains varied characteristic features impacting diagnostic, prognostic and therapeutics. Basal breast tumors, in particular have been challenging in these regards. Basal breast cancer is often more aggressive, of rapid evolution and no tailor-made targeted therapies are available yet to treat it. Arguably, epigenetic variability is behind some of these intricacies. It is possible to further classify basal breast tumor in groups based on their non-coding transcriptome and methylome profiles. It is expected that these groups will have differences in survival as well as in sensitivity to certain classes of drugs. With this in mind, we implemented a computational learning approach to infer different subpopulations of basal breast cancer (from TCGA multi-omic data) based on their epigenetic signatures. Such epigenomic signatures were associated with different survival profiles; we then identified their associated gene co-expression network structure, extracted a signature based on modules within these networks, and use these signatures to find and prioritize drugs (in the LINCS dataset) that may be used to target these types of cancer. In this way we are introducing the analytical workflow for an epigenomic signature-based drug repurposing structure.

Breast cancer stem cell-derived extracellular vesicles transfer ARRDC1-AS1 to promote breast carcinogenesis via a miR-4731-5p/AKT1 axis-dependent mechanism

OBJECTIVES

Deregulation of long non-coding RNAs (lncRNAs) has been frequently reported in breast cancer (BC). This goes to show the importance of understanding its significant contribution towards breast carcinogenesis. In the present study, we clarified a carcinogenic mechanism based on the ARRDC1-AS1 delivered by breast cancer stem cells-derived extracellular vesicles (BCSCs-EVs) in BC.

METHODS

The isolated and well characterized BCSCs-EVs were co-cultured with BC cells. The expression of ARRDC1-AS1, miR-4731-5p, and AKT1 was determined in BC cell lines. BC cells were assayed for their viability, invasion, migration and apoptosis in vitro by CCK-8, Transwell and flow cytometry, as well as tumor growth in vivo after loss- and gain-of function assays. Dual-luciferase reporter gene, RIP and RNA pull-down assays were performed to determine the interactions among ARRDC1-AS1, miR-4731-5p, and AKT1.

RESULTS

Elevation of ARRDC1-AS1 and AKT1 as well as miR-4731-5p downregulation were observed in BC cells. ARRDC1-AS1 was enriched in BCSCs-EVs. Furthermore, EVs containing ARRDC1-AS1 enhanced the BC cell viability, invasion and migration and glutamate concentration. Mechanistically, ARRDC1-AS1 elevated the expression of AKT1 by competitively binding to miR-4731-5p. ARRDC1-AS1-containing EVs were also found to enhance tumor growth in vivo.

CONCLUSION

Collectively, BCSCs-EVs-mediated delivery of ARRDC1-AS1 may promote the malignant phenotypes of BC cells via the miR-4731-5p/AKT1 axis.

Identification of a minimum number of genes to predict triple-negative breast cancer subgroups from gene expression profiles

BACKGROUND

Triple-negative breast cancer (TNBC) is a very heterogeneous disease. Several gene expression and mutation profiling approaches were used to classify it, and all converged to the identification of distinct molecular subtypes, with some overlapping across different approaches. However, a standardised tool to routinely classify TNBC in the clinics and guide personalised treatment is lacking. We aimed at defining a specific gene signature for each of the six TNBC subtypes proposed by Lehman et al. in 2011 (basal-like 1 (BL1); basal-like 2 (BL2); mesenchymal (M); immunomodulatory (IM); mesenchymal stem-like (MSL); and luminal androgen receptor (LAR)), to be able to accurately predict them.

METHODS

Lehman's TNBCtype subtyping tool was applied to RNA-sequencing data from 482 TNBC (GSE164458), and a minimal subtype-specific gene signature was defined by combining two class comparison techniques with seven attribute selection methods. Several machine learning algorithms for subtype prediction were used, and the best classifier was applied on microarray data from 72 Italian TNBC and on the TNBC subset of the BRCA-TCGA data set.

RESULTS

We identified two signatures with the 120 and 81 top up- and downregulated genes that define the six TNBC subtypes, with prediction accuracy ranging from 88.6 to 89.4%, and even improving after removal of the least important genes. Network analysis was used to identify highly interconnected genes within each subgroup. Two druggable matrix metalloproteinases were found in the BL1 and BL2 subsets, and several druggable targets were complementary to androgen receptor or aromatase in the LAR subset. Several secondary drug-target interactions were found among the upregulated genes in the M, IM and MSL subsets.

CONCLUSIONS

Our study took full advantage of available TNBC data sets to stratify samples and genes into distinct subtypes, according to gene expression profiles. The development of a data mining approach to acquire a large amount of information from several data sets has allowed us to identify a well-determined minimal number of genes that may help in the recognition of TNBC subtypes. These genes, most of which have been previously found to be associated with breast cancer, have the potential to become novel diagnostic markers and/or therapeutic targets for specific TNBC subsets.

Analysis of Intrinsic Breast Cancer Subtypes: The Clinical Utility of Epigenetic Biomarkers and TP53 Mutation Status in Triple-Negative Cases

This study aimed at analyzing the DNA methylation pattern and TP53 mutation status of intrinsic breast cancer (BC) subtypes for improved characterization and survival prediction. DNA methylation of 17 genes was tested by methylation-specific PCR in 116 non-familial BRCA mutation-negative BC and 29 control noncancerous cases. At least one gene methylation was detected in all BC specimens and a 10-gene panel statistically significantly separated tumors from noncancerous breast tissues. Methylation of FILIP1L and MT1E was predominant in triple-negative (TN) BC, while other BC subtypes were characterized by RASSF1, PRKCB, MT1G, APC, and RUNX3 hypermethylation. TP53 mutation (TP53-mut) was found in 38% of sequenced samples and mainly affected TN BC cases (87%). Cox analysis revealed that TN status, age at diagnosis, and RUNX3 methylation are independent prognostic factors for overall survival (OS) in BC. The combinations of methylated biomarkers, RUNX3 with MT1E or FILIP1L, were also predictive for shorter OS, whereas methylated FILIP1L was predictive of a poor outcome in the TP53-mut subgroup. Therefore, DNA methylation patterns of specific genes significantly separate BC from noncancerous breast tissues and distinguishes TN cases from non-TN BC, whereas the combination of two-to-three epigenetic biomarkers can be an informative tool for BC outcome predictions.

A systematic review and meta-analysis of BRCA1/2 mutation for predicting the effect of platinum-based chemotherapy in triple-negative breast cancer

INTRODUCTION

Platinum-based chemotherapy (PBC) remains the mainstay of treatments for triple-negative breast cancer (TNBC). TNBC is a heterogeneous group, the issue of whether BRCA1/2 mutation carriers have a particular sensitivity to platinum agents is inconclusive. We conducted a meta-analysis to explore the relationship between BRCA1/2 mutation and PBC susceptibility in individuals with TNBC, aiming to gain more information on the size of the benefit of PBC in BRCA1/2 mutation carriers.

MATERIALS AND METHODS

All studies applying PBC with a subgroup of BRCA1/2 status were included. All endpoints, including pCR and RCB in the neoadjuvant phase, DFS in the adjuvant phase, ORR, PFS, and OS in the advanced phase, were assessed using HRs and 95% Cl.

RESULTS

From the 22 studies included, there were 2158 patients with TNBC, with 392 (18%) bearing the BRCA1/2 gene mutation. Based on 13 studies applying neoadjuvant PBC, we discovered that BRCA1/2 mutation was substantially associated with a 17.6% increased pCR rate (HR 1.32, 95% CI 1.17-1.49, p < 0.00001; I² = 51%). Same result was observed in RCB0/I index (HR 1.38, 95% CI 1.08-1.76, P = 0.009; I² = 0%). The meta-analysis of 6 trials addressing advanced therapy revealed that ORR rates were significantly higher in patients with BRCA1/2 mutation (HR 1.91, 95% CI 1.48-2.47, p < 0.00001; I² = 32%), as well as PFS(HR 1.13, 95% CI 0.81-1.57, P = 0.47; I² = 0%) and OS (HR 1.89, 95% CI 1.22-2.92, P = 0.004; I² = 0%).

CONCLUSION

According to our meta-analysis of 22 trials in TNBC, BRCA1/2 mutation carriers were significantly more sensitive to PBC regimens, especially in neoadjuvant and advanced therapy.

Regulation of cancer stem cells in triple negative breast cancer

Triple Negative Breast Cancer (TNBC) is the most lethal subtype of breast cancer. Despite the successes of emerging targeted therapies, relapse, recurrence, and therapy failure rates in TNBC significantly outpace other subtypes of breast cancer. Mounting evidence suggests accumulation of therapy resistant Cancer Stem Cell (CSC) populations within TNBCs contributes to poor clinical outcomes. These CSCs are enriched in TNBC compared to non-TNBC breast cancers. The mechanisms underlying CSC accumulation have been well-characterized and discussed in other reviews. In this review, we focus on TNBC-specific mechanisms that allow the expansion and activity of self-renewing CSCs. We highlight cellular signaling pathways and transcription factors, specifically enriched in TNBC over non-TNBC breast cancer, contributing to stemness. We also analyze publicly available single-cell RNA-seq data from basal breast cancer tumors to highlight the potential of emerging bioinformatic approaches in identifying novel drivers of stemness in TNBC and other cancers.

Potential epigenetic modifications implicated in triple- to quadruple-negative breast cancer transition: a review

Current research on triple-negative breast cancer (TNBC) has resulted in delineation into the quadruple-negative breast cancer (QNBC) subgroup. Epigenetic modifications such as DNA methylation, histone posttranslational modifications and associated changes in chromatin architecture have been implicated in breast cancer pathogenesis. Herein, the authors highlight genes with observed epigenetic modifications that are associated with more aggressive TNBC/QNBC pathogenesis and possible interventions. Advanced literature searches were done on PubMed/MEDLINE, Scopus and Google Scholar. The results suggest that nine epigenetically altered genes/differentially expressed proteins in addition to the downregulated androgen receptor are associated with TNBC aggressiveness and could be implicated in the TNBC to QNBC transition. Thus, restoring the normal expression of these genes via epigenetic reprogramming could be therapeutically beneficial to TNBC and QNBC patients.

Role of histone demethylases and histone methyltransferases in triple-negative breast cancer: Epigenetic mnemonics

Triple-negative breast cancer (TNBC) is a particularly lethal subtype of breast cancer owing to its heterogeneity, high drug resistance, poor prognosis and lack of therapeutic targets. Recent insights into the complexity of TNBC have been explained by epigenetic regulation and its ability to modulate certain oncogenes and tumour suppressor genes. This has opened an emerging area in anti-cancer therapy using epigenetic modulating drugs, highlighting the epigenetic reprogramming during tumorigenesis and tumour development. Histone methylation and demethylation are such dynamic epigenetic mechanisms mediated by histone methyltransferases (HMTs) and histone demethylases (HDMs), respectively. The interplay between HMTs and HDMs in histone methylation extrapolates their viability as druggable epigenetic targets in TNBC. In this review, we aim to summarize recent progress in the field of epigenetics focusing on HMTs and HDMs in TNBC development and their potential use in targeted therapy for TNBC management.

Triptonide effectively inhibits triple-negative breast cancer metastasis through concurrent degradation of Twist1 and Notch1 oncoproteins

Background

Triple-negative breast cancer (TNBC) is highly metastatic and lethal. Due to a lack of druggable targets for this disease, there are no effective therapies in the clinic.

Methods

We used TNBC cells and xenografted mice as models to explore triptonide-mediated inhibition of TNBC metastasis and tumor growth. Colony formation assay was used to quantify the tumorigenesis of TNBC cells. Wound-healing and cell trans-well assays were utilized to measure cell migration and invasion. Tube formation assay was applied to access tumor cell-mediated vasculogenic mimicry. Western blot, quantitative-PCR, immunofluorescence imaging, and immunohistochemical staining were used to measure the expression levels of various tumorigenic genes in TNBC cells.

Results

Here, we showed that triptonide, a small molecule from the traditional Chinese medicinal herb Tripterygium wilfordii Hook F, potently inhibited TNBC cell migration, invasion, and vasculogenic mimicry, and effectively suppressed TNBC tumor growth and lung metastasis in xenografted mice with no observable toxicity. Molecular mechanistic studies revealed that triptonide strongly triggered the degradation of master epithelial-mesenchymal transition (EMT)-inducing protein Twist1 through the lysosomal system and reduced Notch1 expression and NF-κB phosphorylation, which consequently diminished the expression of pro-metastatic and angiogenic genes N-cadherin, VE-cadherin, and vascular endothelial cell growth factor receptor 2 (VEGFR2).

Conclusions

Triptonide effectively suppressed TNBC cell tumorigenesis, vasculogenic mimicry, and strongly inhibited the metastasis of TNBC via degradation of Twist1 and Notch1 oncoproteins, downregulation of metastatic and angiogenic gene expression, and reduction of NF-κB signaling pathway. Our findings provide a new strategy for treating highly lethal TNBC and offer a potential new drug candidate for combatting this aggressive disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-021-01488-7.

Epigenetic Reprogramming and Landscape of Transcriptomic Interactions: Impending Therapeutic Interference of Triple-Negative Breast Cancer in Molecular Medicine

The mechanisms governing the development and progression of cancers are believed to be the consequence of hereditary deformities and epigenetic modifications. Accordingly, epigenetics has become an incredible and progressively explored field of research to discover better prevention and therapy for neoplasia, especially triple-negative breast cancer (TNBC). It represents 15-20% of all invasive breast cancers and will, in general, have bellicose histological highlights and poor clinical outcomes. In the early phases of triple-negative breast carcinogenesis, epigenetic deregulation modifies chromatin structure and influences the plasticity of cells. It up-keeps the oncogenic reprogramming of malignant progenitor cells with the acquisition of unrestrained selfrenewal capacities. Genomic impulsiveness in TNBC prompts mutations, copy number variations, as well as genetic rearrangements, while epigenetic remodeling includes an amendment by DNA methylation, histone modification, and noncoding RNAs of gene expression profiles. It is currently evident that epigenetic mechanisms assume a significant part in the pathogenesis, maintenance, and therapeutic resistance of TNBC. Although TNBC is a heterogeneous malaise that is perplexing to describe and treat, the ongoing explosion of genetic and epigenetic research will help to expand these endeavors. Latest developments in transcriptome analysis have reformed our understanding of human diseases, including TNBC at the molecular medicine level. It is appealing to envision transcriptomic biomarkers to comprehend tumor behavior more readily regarding its cellular microenvironment. Understanding these essential biomarkers and molecular changes will propel our capability to treat TNBC adequately. This review will depict the different aspects of epigenetics and the landscape of transcriptomics in triple-negative breast carcinogenesis and their impending application for diagnosis, prognosis, and treatment decision with the view of molecular medicine.

Molecular epigenetic dynamics in breast carcinogenesis

Breast cancer has become one of the most common dreadful diseases that target women across the globe. The most obvious reasons we associate with it are either genetic mutations or dysregulation of pathways. However, there is yet another domain that has a significant role in influencing the genetic mutations and pathways. Epigenetic mechanisms influence these pathways either independently or in association with genetic mutations, thereby expediting the process of breast carcinogenesis. Breast cancer is governed by various transduction pathways such as PI3K/AKT/mTOR, NOTCH, β Catenin, NF-kB, Hedgehog, etc. There are many proteins as well that serve to be tumor suppressors but somehow lose their ability to function. This may be because of either genetic mutation or a process that represses their function. Apart from these, there are a lot of individual factors like puberty, breastfeeding, abortion, parity, circadian rhythm, alcohol consumption, pollutants, and obesity that drive these mutations and hence alter the pathways. Epigenetic mechanisms like DNA methylation, histone modifications, and lncRNAs directly or indirectly bring alterations in the proteins that are involved in the pathways. They do this by either promoting the transcription of genes or by repressing it at the ground genetic level that advances breast carcinogenesis. Epigenetics precedes genetic mutation in driving carcinogenesis and so, it needs to be explored further to diversify the possibilities of target specific treatments. In this review, the general role of DNA methylation, histone modification, and lncRNAs in breast cancer and their role in influencing the oncogenic signaling pathways along with the various factors governing them have been discussed for a better understanding of the role of epigenetics in breast carcinogenesis.

Epigenetics of Triple-negative breast cancer via natural compounds

Triple-negative breast cancer (TNBC) is a highly resistant, lethal, and metastatic sub-division of breast carcinoma, characterized by the deficiency of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). In women, TNBC shows a higher aggressive behavior with poor patient prognosis and a higher recurrence rate during reproductive age. TNBC is defined by the presence of epithelial-to-mesenchymal-transition (EMT), which shows a significant role in cancer progression. At the epigenetic level, TNBC is characterized by epigenetic signatures, such as DNA methylation, histone remodeling, and a host of miRNA, MiR-193, LncRNA, HIF-2α, eEF2K, LIN9/NEK2, IMP3, LISCH7/TGF-β1, GD3s and KLK12 mediated regulation. These modifications either are silenced or activate the necessary genes that are prevalent in TNBC. The review is based on epigenetic mediated mechanistic changes in TNBC. Furthermore, Thymoquinone (TQ), Regorafenib, Fangjihuangqi decoction, Saikosaponin A, and Huaier, etc., are potent antitumor natural compounds extensively reported in the literature. Further, the review emphasizes the role of these natural compounds in TNBC and their possible epigenetic targets, which can be utilized as a potential therapeutic strategy in treatment of TNBC.

The Roles of DNA Demethylases in Triple-Negative Breast Cancer

Triple-negative breast cancers (TNBCs) are very heterogenous, molecularly diverse, and are characterized by a high propensity to relapse or metastasize. Clinically, TNBC remains a diagnosis of exclusion by the lack of hormone receptors (Estrogen Receptor (ER) and Progesterone Receptor (PR)) as well as the absence of overexpression and/or amplification of HER2. DNA methylation plays an important role in breast cancer carcinogenesis and TNBCs have a distinct DNA methylation profile characterized by marked hypomethylation and lower gains of methylations compared to all other subtypes. DNA methylation is regulated by the balance of DNA methylases (DNMTs) and DNA demethylases (TETs). Here, we review the roles of TETs as context-dependent tumor-suppressor genes and/or oncogenes in solid tumors, and we discuss the current understandings of the oncogenic role of TET1 and its therapeutic implications in TNBCs.

An Assessment on Ethanol-Blended Gasoline/Diesel Fuels on Cancer Risk and Mortality

Although cancer is traditionally considered a genetic disease, the epigenetic abnormalities, including DNA hypermethylation, histone deacetylation, and/or microRNA dysregulation, have been demonstrated as a hallmark of cancer. Compared with gene mutations, aberrant epigenetic changes occur more frequently, and cellular epigenome is more susceptible to change by environmental factors. Excess cancer risks are positively associated with exposure to occupational and environmental chemical carcinogens, including those from gasoline combustion exhausted in vehicles. Of note, previous studies proposed particulate matter index (PMI) as a measure for gasoline sooting tendency, and showed that, compared with the other molecules in gasoline, 1,2,4-Trimethylbenzene, 2-methylnaphthalene and toluene significantly contribute to PMI of the gasoline blends. Mechanistically, both epigenome and genome are important in carcinogenicity, and the genotoxicity of chemical agents has been thoroughly studied. However, less effort has been put into studying the epigenotoxicity. Moreover, as the blending of ethanol into gasoline substitutes for carcinogens, like benzene, toluene, xylene, butadiene, and polycyclic aromatic hydrocarbons, etc., a reduction of secondary aromatics has been achieved in the atmosphere. This may lead to diminished cancer initiation and progression through altered cellular epigenetic landscape. The present review summarizes the most important findings in the literature on the association between exposures to carcinogens from gasoline combustion, cancer epigenetics and the potential epigenetic impacts of biofuels.

Doxorubicin-paclitaxel sequential treatment: insights of DNA methylation and gene expression changes of luminal A and triple negative breast cancer cell lines

Breast cancer is one of the significant causes of death among women diagnosed with cancer worldwide. Even though several chemotherapy combinations are still the primary treatment of breast cancer, unsuccessful treatments, and poor prognostic outcomes are still being reported. DNA methylation and gene expression changes among two breast cancer cell lines representing luminal A (MCF-7) and triple-negative (MDA-MB-231) cancers were determined after sequential combination treatment of doxorubicin and paclitaxel and analyzed using Ingenuity Pathway Analysis. Promoter methylation changes were seen in different treated MCF-7 cells and accompanied by changes in the gene expression of CCNA1 and PTGS2. In MDA-MB-231 cells, the hypomethylation of ESR1 was not accompanied by an increase in its gene expression in any treated cells. The hypomethylation of GSTP1 and MGMT was accompanied by an increase in gene expression levels in the group treated with doxorubicin only. Also, significant downregulation of several genes like MUC1 and MKI67 in MCF-7 cells treated with doxorubicin showed much lower gene expression (- 37.63, - 10.88 folds) when compared with cells treated with paclitaxel (- 2.47, - 2.05 folds) or the combination treatment (- 18.99, - 2.81 folds), respectively. On the other hand, a synergistic effect on MMP9 gene expression was significantly seen in MDA-MB-231 cells treated with the combination (- 9.99 folds) in comparison with the cells treated with doxorubicin (- 3.62 folds) or paclitaxel (1.75 folds) alone. Chemotherapy combinations do not always augment the molecular changes seen in each drug alone, and these changes could be utilized as treatment response markers.

Glucocorticoid Receptor: A Multifaceted Actor in Breast Cancer

Breast cancer (BC) is one of the most common cancers in women worldwide. Even though the role of estrogen receptor alpha (ERα) is extensively documented in the development of breast tumors, other members of the nuclear receptor family have emerged as important players. Synthetic glucocorticoids (GCs) such as dexamethasone (dex) are commonly used in BC for their antiemetic, anti-inflammatory, as well as energy and appetite stimulating properties, and to manage the side effects of chemotherapy. However, dex triggers different effects depending on the BC subtype. The glucocorticoid receptor (GR) is also an important marker in BC, as high GR expression is correlated with a poor and good prognosis in ERα-negative and ERα-positive BCs, respectively. Indeed, though it drives the expression of pro-tumorigenic genes in ERα-negative BCs and is involved in resistance to chemotherapy and metastasis formation, dex inhibits estrogen-mediated cell proliferation in ERα-positive BCs. Recently, a new natural ligand for GR called OCDO was identified. OCDO is a cholesterol metabolite with oncogenic properties, triggering mammary cell proliferation in vitro and in vivo. In this review, we summarize recent data on GR signaling and its involvement in tumoral breast tissue, via its different ligands.

The Anticancer Effects of Flavonoids through miRNAs Modulations in Triple-Negative Breast Cancer

Triple- negative breast cancer (TNBC) incidence rate has regularly risen over the last decades and is expected to increase in the future. Finding novel treatment options with minimum or no toxicity is of great importance in treating or preventing TNBC. Flavonoids are new attractive molecules that might fulfill this promising therapeutic option. Flavonoids have shown many biological activities, including antioxidant, anti-inflammatory, and anticancer effects. In addition to their anticancer effects by arresting the cell cycle, inducing apoptosis, and suppressing cancer cell proliferation, flavonoids can modulate non-coding microRNAs (miRNAs) function. Several preclinical and epidemiological studies indicate the possible therapeutic potential of these compounds. Flavonoids display a unique ability to change miRNAs' levels via different mechanisms, either by suppressing oncogenic miRNAs or activating oncosuppressor miRNAs or affecting transcriptional, epigenetic miRNA processing in TNBC. Flavonoids are not only involved in the regulation of miRNA-mediated cancer initiation, growth, proliferation, differentiation, invasion, metastasis, and epithelial-to-mesenchymal transition (EMT), but also control miRNAs-mediated biological processes that significantly impact TNBC, such as cell cycle, immune system, mitochondrial dysregulation, modulating signaling pathways, inflammation, and angiogenesis. In this review, we highlighted the role of miRNAs in TNBC cancer progression and the effect of flavonoids on miRNA regulation, emphasizing their anticipated role in the prevention and treatment of TNBC.

Protein arginine methyltransferase 5 (PRMT5) activates WNT/β-catenin signalling in breast cancer cells via epigenetic silencing of DKK1 and DKK3

Protein arginine methyltransferase 5 (PRMT5) activity is dysregulated in many aggressive cancers and its enhanced levels are associated with increased tumour growth and survival. However, the role of PRMT5 in breast cancer remains underexplored. In this study, we show that PRMT5 is overexpressed in breast cancer cell lines, and that it promotes WNT/β-CATENIN proliferative signalling through epigenetic silencing of pathway antagonists, DKK1 and DKK3, leading to enhanced expression of c-MYC, CYCLIN D1 and SURVIVIN. Through chromatin immunoprecipitation (ChIP) studies, we found that PRMT5 binds to the promoter region of WNT antagonists, DKK1 and DKK3, and induces symmetric methylation of H3R8 and H4R3 histones. Our findings also show that PRMT5 inhibition using a specific small molecule inhibitor, compound 5 (CMP5), reduces PRMT5 recruitment as well as methylation of H3R8 and H4R3 histones in the promoter regions of DKK1 and DKK3, which consequently results in reduced expression CYCLIN D1 and SURVIVIN. Furthermore, CMP5 treatment either alone or in combination with 5-Azacytidine and Trichostatin A restored expression of DKK1 and DKK3 in TNBCs. PRMT5 inhibition also altered the growth characteristics of breast cancer cells and induced their death. Collectively, these results show that PRMT5 controls breast cancer cell growth through epigenetic silencing of WNT/β-CATENIN pathway antagonists, DKK1 and DKK3, resulting in up-regulation of WNT/β-CATENIN proliferative signalling.

ARG1 functions as a tumor suppressor in breast cancer

Arginase I (ARG1) is a cytosolic enzyme that catalyzes the hydrolysis of L-arginine to L-ornithine and urea. The association of ARG1 with cancer has mostly been focused on the ARG1 released by tumor-associated myeloid cells in tumor microenvironment. However, the role of ARG1 expressed in cancer cells is unclear. Here, we showed that the expression of ARG1 in human breast cancer (BC) is related to a good prognosis in BC patients. Overexpression of ARG1 suppresses BC cell proliferation and migration in vitro and xenograft tumor growth and development in mouse models. Furthermore, ARG1 expression down-regulates the expression of p-AKT, leading to the de-activation of AKT signal pathway in BC cells. Thus, our results established that in contrast to the role of ARG1 released from tumor-associated myeloid cells in tumor microenvironment that promotes tumor immune escape, ARG1 expressed in BC cells suppresses AKT signaling pathway and functions as a tumor suppressor.

Identification of Novel MeCP2 Cancer-Associated Target Genes and Post-Translational Modifications

Abnormal regulation of DNA methylation and its readers has been associated with a wide range of cellular dysfunction. Disruption of the normal function of DNA methylation readers contributes to cancer progression, neurodevelopmental disorders, autoimmune disease and other pathologies. One reader of DNA methylation known to be especially important is MeCP2. It acts a bridge and connects DNA methylation with histone modifications and regulates many gene targets contributing to various diseases; however, much remains unknown about how it contributes to cancer malignancy. We and others previously described novel MeCP2 post-translational regulation. We set out to test the hypothesis that MeCP2 would regulate novel genes linked with tumorigenesis and that MeCP2 is subject to additional post-translational regulation not previously identified. Herein we report novel genes bound and regulated by MeCP2 through MeCP2 ChIP-seq and RNA-seq analyses in two breast cancer cell lines representing different breast cancer subtypes. Through genomics analyses, we localize MeCP2 to novel gene targets and further define the full range of gene targets within breast cancer cell lines. We also further examine the scope of clinical and pre-clinical lysine deacetylase inhibitors (KDACi) that regulate MeCP2 post-translationally. Through proteomics analyses, we identify many additional novel acetylation sites, nine of which are mutated in Rett Syndrome. Our study provides important new insight into downstream targets of MeCP2 and provide the first comprehensive map of novel sites of acetylation associated with both pre-clinical and FDA-approved KDACi used in the clinic. This report examines a critical reader of DNA methylation and has important implications for understanding MeCP2 regulation in cancer models and identifying novel molecular targets associated with epigenetic therapies.

Triple-Negative Breast Cancer Comparison With Canine Mammary Tumors From Light Microscopy to Molecular Pathology

Many similar characteristics in human and dog cancers including, spontaneous development, clinical presentation, tumor heterogeneity, disease progression, and response to standard therapies have promoted the approval of this comparative model as an alternative to mice. Breast cancer represents the second most frequent neoplasm in humans after lung cancer. Triple-negative breast cancers (TNBC) constitute around 15% of all cases of breast cancer and do not express estrogen receptor (ER), progesterone receptor (PR), and do not overexpress human epidermal growth factor receptor 2 (HER2). As a result, they do not benefit from hormonal or trastuzumab-based therapy. Patients with TNBC have worse overall survival than patients with non-TNBC. Lehmann and collaborators described six different molecular subtypes of TNBC which further demonstrated its transcriptional heterogeneity. This six TNBC subtype classification has therapeutic implications. Breast cancer is the second most frequent neoplasm in sexually intact female dogs after skin cancer. Canine mammary tumors are a naturally occurring heterogeneous group of cancers that have several features in common with human breast cancer (HBC). These similarities include etiology, signaling pathway activation, and histological classification. Molecularly CMTs are more like TNBCs, and therefore dogs are powerful spontaneous models of cancer to test new therapeutic approaches, particularly for human TNBCs. More malignant tumors of the breast are more often ER and PR negative in both humans and dogs. Promising breast cancer biomarkers in both humans and canines are cancer-associated stroma (CAS), circulating tumor cells and tumor DNA (ctDNA), exosomes and miRNAs, and metabolites.

Thermosensitive Betulinic Acid-Loaded Magnetoliposomes: A Promising Antitumor Potential for Highly Aggressive Human Breast Adenocarcinoma Cells Under Hyperthermic Conditions

PURPOSE

Breast cancer presents one of the highest rates of prevalence around the world. Despite this, the current breast cancer therapy is characterized by significant side effects and high risk of recurrence. The present work aimed to develop a new therapeutic strategy that may improve the current breast cancer therapy by developing a heat-sensitive liposomal nano-platform suitable to incorporate both anti-tumor betulinic acid (BA) compound and magnetic iron nanoparticles (MIONPs), in order to address both remote drug release and hyperthermia-inducing features. To address the above-mentioned biomedical purposes, the nanocarrier must possess specific features such as specific phase transition temperature, diameter below 200 nm, superparamagnetic properties and heating capacity. Moreover, the anti-tumor activity of the developed nanocarrier should significantly affect human breast adenocarcinoma cells.

METHODS

BA-loaded magnetoliposomes and corresponding controls (BA-free liposomes and liposomes containing no magnetic payload) were obtained through the thin-layer hydration method. The quality and stability of the multifunctional platforms were physico-chemically analysed by the means of RAMAN, scanning electron microscopy-EDAX, dynamic light scattering, zeta potential and DSC analysis. Besides this, the magnetic characterization of magnetoliposomes was performed in terms of superparamagnetic behaviour and heating capacity. The biological profile of the platforms and controls was screened through multiple in vitro methods, such as MTT, LDH and scratch assays, together with immunofluorescence staining. In addition, CAM assay was performed in order to assess a possible anti-angiogenic activity induced by the test samples.

RESULTS

The physico-chemical analysis revealed that BA-loaded magnetoliposomes present suitable characteristics for the purpose of this study, showing biocompatible phase transition temperature, a diameter of 198 nm, superparamagnetic features and heating capacity. In vitro results showed that hyperthermia induces enhanced anti-tumor activity when breast adenocarcinoma MDA-MB-231 cells were exposed to BA-loaded magnetoliposomes, while a low cytotoxic rate was exhibited by the non-tumorigenic breast epithelial MCF 10A cells. Moreover, the in ovo angiogenesis assay endorsed the efficacy of this multifunctional platform as a good strategy for breast cancer therapy, under hyperthermal conditions. Regarding the possible mechanism of action of this multifunctional nano-platform, the immunocytochemistry of the MCF7 and MDA-MB-231 breast carcinoma cells revealed a microtubule assembly modulatory activity, under hyperthermal conditions.

CONCLUSION

Collectively, these findings indicate that BA-loaded magnetoliposomes, under hyperthermal conditions, might serve as a promising strategy for breast adenocarcinoma treatment.

Bispecific Antibodies for Triple Negative Breast Cancer

Triple negative breast cancer (TNBC), an aggressive breast cancer subtype lacking estrogen receptor (ER), progesterone receptor, and human epidermal growth factor receptor 2 (HER2) expression, is associated with heightened metastatic potential and poor prognosis. While systemic chemotherapy, radiation, and surgical excision remain the current treatment modalities for patients with TNBC, the immunogenic nature of this aggressive disease has presented opportunity for the development of TNBC-targeting immunotherapies. Bispecific antibody-based therapeutics for the treatment of TNBC have gained recent attention in the scientific community. Clinical precedent has been previously established for the FDA-approved bispecific T cell engager, blinatumomab, for acute lymphoblastic leukemia. The present review discusses novel bispecific antibodies for TNBC and emerging TNBC targets for future bispecific antibody development.

Predictors of Response and Survival Outcomes of Triple Negative Breast Cancer Receiving Neoadjuvant Chemotherapy

BACKGROUND

In triple negative breast cancer (TNBC) patients receiving neoadjuvant chemotherapy (NACT), pre-treatment predictors for pathological complete response (pCR) have been reported; however, those for progressive disease (PD) remain unidentified.

METHODS

We investigated pre-treatment clinicopathological predictors associated with pCR and PD by retrospectively reviewing data for 165 patients treated between 2015 and 2018. Patients with pCR and PD were compared to those without pCR and PD, respectively, using logistic regression and Kaplan-Meier methods.

RESULTS

Lack of androgen receptor (AR) was an independent predictor of pCR, while high histological grade, low Ki-67 index, and incomplete NACT courses were independent predictors of PD. Mean disease-free survival and overall survival were significantly poorer in PD patients than in pCR patients (15.7, 21.3 vs. 52.4, 56.3 months).

CONCLUSIONS

Insights into the chemo-resistance mechanisms and exploration of novel targeted agents in subgroups as per AR and Ki-67 status are needed to improve survival outcomes in TNBC patients.

Long non-coding RNA LRRC75A-AS1 facilitates triple negative breast cancer cell proliferation and invasion via functioning as a ceRNA to modulate BAALC

As a common female malignancy, triple-negative breast cancer (TNBC) is the most serious subtype in breast cancer (BC). BAALC binder of MAP3K1 and KLF4 (BAALC) is a common oncogene in acute myelocytic leukemia (AML). We sought to explore the role of BAALC in TNBC. In this study, BAALC was significantly upregulated in TNBC tissues and cells. Then, the results of functional assays disclosed that BAALC facilitated cell proliferation, invasion, and epithelial–mesenchymal transition (EMT) processes, but repressed cell apoptosis in TNBC. Next, miR-380–3p was identified as the upstream of BAALC in TNBC cells. Moreover, LRRC75A-AS1 (also named small nucleolar RNA host gene 29: SNHG29) was verified to act as the sponge of miR-380–3p to elevate BAALC expression in TNBC. Besides, LRRC75A-AS1 could negatively regulate miR-380–3p but positively regulate BAALC expression. Finally, rescue assays elucidated that LRRC75A-AS1 facilitated cell proliferation, invasion, and EMT processes in TNBC by targeting miR-380–3p/BAALC pathway. Taken together, our study revealed a novel ceRNA network of LRRC75A-AS1/miR-380–3p/BAALC in accelerating TNBC development, indicating new promising targets for TNBC treatment.

Promoter Hypermethylation and Expression Changes of BRCA1 Gene in a Cohort of Sporadic Breast Cancer Cases among Pakistani Population

Objective:

The purpose of our study was to determine the frequency of BRCA1 promoter hypermethylation and its association with expression changes of BRCA1 and main morphological features in sporadic breast cancer.

Methods:

A retrospective review of cases was performed to select those with specific morphological features suggestive of breast cancer. BRCA1 promoter hypermethylation and changes in protein expression were evaluated in 30 cancerous and 30 non-cancerous tissue samples. A tissue microarray containing samples from normal and tumor tissue was prepared and stained for BRCA1 protein expression using a commercially available monoclonal antibody against BRCA1 (Ab-1) clone MS110 (mAb). DNA was extracted using modified protocol of Qiagen minikit. DNA was modified using a Bisulfite conversion kit and BRCA1 hypermethylation was detected using a methylation specific PCR.

Results:

Promoter hypermethylation was negative in 30 non-cancerous samples with retained BRCA1 protein expression. Methylation was positive in 82.6% (n=19/23) of the sporadic cancer samples that had loss of BRCA1 expression and 50% (n=2/4) of the samples with equivocal protein expression. Methylation was negative in all the sporadic breast cancer samples (n=3/3) with retained protein expression. Chi-square analysis showed significant association of BRCA1 promoter methylation with decreased protein expression (P=0.016) and co-existence of loss of BRCA1 and Her2neu at chromosome 17 (P=0.026) respectively. There was no significant association of BRCA1 methylation with morphological features excluding necrosis (P=0.035). Promoter hypermethylation was found to be most common (68.75%) among Triple Negative Breast Cancer (TNBC) females less than 45 years old.

Conclusion:

Our study suggests that BRCA1 promoter hypermethylation has significant contribution in sporadic breast carcinogenesis. This was our preliminary study in Pakistan. Further studies aimed to determine the in-depth mechanisms of BRCA1 epigenetics in TNBC. BRCAness enriched phenotype in TNBC might be used as a biomarker for the exploitation of therapeutic and clinical implications.

Identification of Potential Key Genes Associated With the Pathogenesis, Metastasis, and Prognosis of Triple-Negative Breast Cancer on the Basis of Integrated Bioinformatics Analysis

Objective: Breast cancer is the most common solid tumor affecting women and the second leading cause of cancer-related death worldwide, and triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer. We aimed to identify potential TNBC-specific therapeutic targets by performing an integrative analysis on previously published TNBC transcriptome microarray data.

Methods: Differentially expressed genes (DEGs) between TNBC and normal breast tissues were screened using six Gene Expression Omnibus (GEO) datasets, and DEGs between metastatic TNBC and non-metastatic TNBC were screened using one GEO dataset. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analyses were performed on the overlapping DEGs. The Cancer Genome Atlas (TCGA) TNBC data were used to identify candidate genes that were strongly associated with survival. Expression of the candidate genes in TNBC cell lines was blocked or augmented using a lentivirus system, and transwell assays were used to determine their effect on TNBC migration.

Results: Eight upregulated genes and nine downregulated genes were found to be differentially expressed both between TNBC and normal breast tissues and between metastatic TNBC and non-metastatic TNBC. Among them, S100P and SDC1 were identified as poor prognostic genes. Furthermore, compared with control cells, SDC1-overexpressing TNBC cells showed enhanced migration ability, whereas SDC1 knockdown markedly reduced the migration of TNBC cells.

Conclusion: Our study determined that S100P and SDC1 may be potential treatment targets as well as prognostic biomarkers of TNBC.

Inhibitor of Interleukin-1 Receptor-associated Kinases 1/4, Can Increase the Sensitivity of Breast Cancer Cells to Methotrexate

Breast cancer is the most common type of cancer among women. Chemotherapy is one of the main methods of breast cancer treatment, but this method is increasingly affected due to drug resistance. One of the newly discovered factors associated with drug resistance in cancer cells is interleukin receptor-associated kinase 1 (IRAK1). The aim of this study was to investigate the relationship between IRAK1 inhibition and sensitivity to methotrexate (MTX). Effects of various concentrations of MTX and constant concentration (1μg/ml) of IRAK1/4 inhibitor was examined on MCF-7, BT-20, BT-549, MB-468 cell lines. Cell viability was examined by water soluble tetrazole -1, and cell apoptosis by flow cytometry. The expression of IRAK1 and BCRP genes was also assessed by real-time PCR method. IRAK1 inhibitor decreased IC₅₀ in all examined cell lines, but the most prominent effect was observed in MB-468. 72 h incubation of cell lines with IRAK inhibitor and MTX, significantly increased the annexin-V and annexin-V/7AAD positive cells, suggesting an apoptotic effect of IRAK on all examined breast cancer cell lines. RT-qPCR test results showed that the IRAK inhibitor had no effect on the expression of BCRP at any time. Our results showed that IRAK inhibitor can increase the chemosensitivity of breast cancer cell lines without effect on BCRP mRNA expression. IRAK inhibitor in combination with MTX can induce apoptosis in breast cancer cell lines.

miR-187-3p increases gemcitabine sensitivity in breast cancer cells by targeting FGF9 expression

Breast cancer is the most common type of malignancy in women, which remains a significant health concern worldwide. Gemcitabine is a frequently applied anticancer pharmacological agent. However, the efficacy of gemcitabine is limited by chemoresistance. In the present study, a combination of reverse transcription quantitative-PCR, cell viability, flow cytometry, luciferase reporter assay and western blot analysis were performed to elucidate the potential effects of miR-187-3p on gemcitabine sensitivity in the breast cancer cell line, MDA-MB-231. The results revealed that miR-187-3p was significantly decreased in the breast cancer tumor tissues. Moreover, the overexpression of miR-187-3p significantly inhibited cell viability and promoted apoptosis in MDA-MB-231 cells. In addition, miR-187-3p overexpression enhanced the anti-proliferative and pro-apoptotic effects of gemcitabine, indicating that miR-187-3p regulated gemcitabine sensitivity in breast cancer cells. Mechanistically, miR-187-3p negatively regulated the expression of fibroblast growth factor 9 (FGF9) by binding to its 3'-untranslated region. Overexpression of FGF9 reversed the aforementioned effects of miR-187-3p overexpression on cell viability and apoptosis in the presence of gemcitabine. In conclusion, the present study indicated that miR-187-3p increased gemcitabine sensitivity in breast cancer cells by targeting FGF9 expression.

Efficacy of platinum in advanced triple-negative breast cancer with germline BRCA mutation determined by next generation sequencing

Objective

To compare the efficacy of platinum- and non-platinum-based regimens as first-line treatment for advanced triple-negative breast cancer (TNBC) and analyze the relationship between their efficacy and BRCA gene status.

Methods

Retrospectively analyze clinical data of 220 patients diagnosed pathologically with advanced TNBC and treated at the Department of Breast Oncology, Peking University Cancer Hospital from 2013 to 2018 and evaluate the efficacy of chemotherapy. A total of 114 patients had BRCA1/2 gene tested by next generation sequencing (NGS) using peripheral blood, and we analyzed the correlation between their efficacy and BRCA1/2 gene status.

Results

Non-platinum-based chemotherapy (NPCT) was administered to 129 and platinum-based chemotherapy (PBCT) to 91 study patients. The clinical benefit rate (CBR) and median progression-free survival (PFS) were not statistically different between NPCT and PBCT groups. The median overall survival (OS) was 30.0 and 22.5 months for PBCT and NPCT group, respectively [P=0.090, hazard ratios (HR)=0.703]. BRCA status was assessed in 114 patients, 14 of whom had deleterious germline BRCA1/2 (gBRCA) mutations (seven in each group). In PBCT group, the CBR was 85.7% and 35.1% for patients with and without deleterious gBRCA mutations, respectively (P=0.039). The median PFS were 14.9 and 5.3 months and median OS were 26.5 and 15.5 months for patients with and without deleterious gBRCA mutations, respectively (P=0.001, P=0.161, respectively). Patients in PBCT group had significantly greater rates of grade 3−4 anemia (5.5%vs. 0%) and thrombocytopenia (8.8% vs. 0%), whereas palmar-plantar erythrodysesthesia (12.4% vs. 0%) and peripheral neuropathy (8.6% vs. 1.1%) occurred more frequently in NPCT group.

Conclusions

Platinum-based regimens are more effective in patients with deleterious gBRCA mutations, but no difference in patients without BRCA gene mutations, so non-platinum is an option in patients without BRCA gene mutations considering the toxicity and side effect. And we recommend that patients with advanced TNBC should have BRCA gene test.

Epi-drugs as triple-negative breast cancer treatment

Triple-negative breast cancer (TNBC) types with poor prognosis are due to the absence of estrogen receptors, progesterone receptors and HEGFR-2. The lack of suitable therapy for TNBC has led the research community to turn toward epigenetic regulation and its protagonists that can modulate certain oncogenes and tumor suppressors. This has opened an important new field of therapy using epi-drugs, in preclinical and clinical trials. The epi-drugs are natural or synthetic molecules capable of inhibiting or modulating the activity of epigenetic proteins such as DNA methyltransferases, modulating the expression of interferon microRNAs, as well as histone methyltransferases, demethylases, acetyltransferases and deacetylases. This review investigated the epi-drugs used in the treatment of TNBC.

Association of HDAC8 Expression with Pathological Findings in Triple Negative and Non-Triple Negative Breast Cancer: Implications for Diagnosis

Background:

Previous data have shown the tumorigenicity roles of HDAC8 in breast cancer. More recently, the oncogenic effects of this molecule have been revealed in TNBC. The present study aimed to determine the diagnostic value of HDAC8 for the differentiation of TNBC from nTNBC tumors.

Methods:

A total of 50 cancerous and normal adjacent tumor specimens were obtained, and the clinical and pathological findings of studied subjects were recorded. The expression of HDAC8 gene was determined by qRT-PCR. Also, immunohistochemical staining was performed on tissue samples.

Results:

Our results showed that the expression of HDAC8 in breast cancer tissues was significantly higher than the normal adjacent tissues (p = 0.0011). HDAC8 expression was also observed to be higher in TNBC patients than nTNBC group (p = 0.0013). In addition, in the TNBC group, there was a significant association between the HDAC8 overexpression and tumor characteristics, including tumor size (p = 0.039), lymphatic invasion (p = 0.01), tumor grade (p = 0.02), and perineural invasion (p < 0.05). The cut-off value was fixed at 0.6279 r.u., and the corresponding sensitivity and specificity were found to be 73.91% and 70.37%, respectively.

Conclusion:

According to the findings, among the other markers, HDAC8 oncogene may be used as a potential tumor marker in diagnosis of TNBC tumors.

CHARACTERISTICS AND PROGNOSIS OF TRIPLE-NEGATIVE BREAST CANCER PATIENTS: A CROATIAN SINGLE INstitution RETROSPECTIVE COHORT STUDY

Triple-negative breast cancer (TNBC) occurs in around one-sixth of all breast cancer (BC) patients, with the most aggressive behavior and worst prognosis of all BC subtypes. It is a heterogeneous disease, with specific molecular characteristics and natural dynamics of early recurrence and fast progression. Due to the lack of biomarkers or any valid treatment targets, it can only be treated with classic cytotoxic chemotherapy. We analyzed a cohort of 152 patients, median age 58 years, diagnosed with and treated for early stage TNBC at the University Hospital for Tumors, Sestre milosrdnice University Hospital Centre, Zagreb, Croatia, during the 2009-2012 period. Patients were treated with primary surgical approach, adjuvant chemotherapy and adjuvant irradiation. We observed a relatively large proportion of locally advanced TNBC at diagnosis, with large tumor size and nodal involvement, with high grade and high proliferation index Ki67. Patient age, tumor size and lymph node involvement, as expected, were significant and clinically most important prognostic factors for 5-year disease-free survival (67%; 95% CI 60%-75%) and overall absolute survival rate (74%; 95% CI 66%-81%).

Addition of docosahexaenoic acid synergistically enhances the efficacy of apatinib for triple-negative breast cancer therapy

The current study aimed to investigate the antitumor and antiangiogenesis effects of apatinib in triple-negative breast cancer in vitro and also whether the combination of docosahexaenoic acid (DHA) and apatinib is more effective than apatinib monotherapy. The cell counting kit-8 assay was used to measure cell proliferation. Flow cytometry was utilized to determine the cell apoptosis rate. A wound healing assay was utilized to assess cell migration. Western blot analysis was carried out to determine the effects of apatinib and DHA on Bcl-2, BAX, cleaved caspase-3, caspase-3, phosphorylated protein kinase B (p-Akt), and Akt expression. DHA in combination with apatinib showed enhanced inhibitory effects on cell proliferation and migration compared with apatinib or DHA monotherapy. Meanwhile, DHA combined with apatinib strongly increased the cell apoptosis percentage. DHA was observed to enhance the antitumor and antiangiogenesis effects of apatinib via further downregulation of p-Akt expression.Abbreviations: FITC: fluorescein isothiocyanate; PI: propidium iodide.

Targeting DNA methylation for treating triple-negative breast cancer

Triple-negative breast cancer (TNBC) accounts for 15-20% of all invasive breast cancers and tends to have aggressive histological features and poor clinical outcomes. Unlike, estrogen receptor- or HER2-positive diseases, TNBC patients currently lack the US FDA-approved targeted therapies. DNA methylation is a critical mechanism of epigenetic modification. It is well known that aberrant DNA methylation contributes to the malignant transformation of cells by silencing critical tumor suppressor genes. DNA methyltransferase inhibitors reactivate silenced tumor suppressor genes and result in tumor growth arrest, with therapeutic effects observed in patients with hematologic malignancies. The antitumor effect of these DNA methyltransferase inhibitors has also been explored in solid tumors, especially in TNBC that currently lacks targeted therapies.

Nek2B activates the wnt pathway and promotes triple-negative breast cancer chemothezrapy-resistance by stabilizing β-catenin

Background

The chemotherapy-resistance of triple-negative breast cancer (TNBC) remains a major challenge. The Nek2B kinase and β-catenin serve as crucial regulators of mitotic processes. The aim of this study was to test the correlation between Nek2B and TNBC chemotherapy sensitivity, and to determine the regulation of Nek2B on β-catenin and wnt/β-catenin signal pathway.

Methods

Gene Expression Omnibus(GEO) databases were used to gather gene exprsssion data of TNBC patients who undergoing chemotherapy. The co-expression of Nek2B and β-catenin in TNBC surgical sections and cells were analysed by immunohistochemistry, Q-RT-PCR, Western-blot and immunofluorescent staining. The impact of the expression of Nek2B and β-catenin in prognosis was also assessed using the Kaplan-Meier curves. CCK8 assay was used to detect the IC50 value of TNBC cell line. The endogenous binding capacity of Nek2B and β-catenin and phosphorylation of β-catenin by Nek2B were detected using co-immunoprecipitation (CO-IP). Chromatin immune-precipitation (ChIP) analysis and Luciferase Assays were used to evaluate the binding ability of the Nek2B, β-catenin and TCF4 complex with LEF-1 promoter. Nek2B-siRNA and Nek2B plasmid were injected into nude mice, and tumorigenesis was monitored.

Results

We found that overexpression of Nek2B and β-catenin in TNBC samples, was associated with patients poor prognosis. Patients with positive Nek2B expression were less sensitive to paclitaxel-containing neoadjuvant chemotherapy. Interestingly, in a panel of established TNBC cell line, Nek2B and β-catenin were highly expressed in cells exhibiting paclitaxel resistance. Our data also suggest that β-catenin binded to and was phosphorylated by Nek2B, and was in a complex with TCF4. Nek2B mainly regulates the expression of β-catenin in TNBC nucleus. Nek2B, β-catenin and TCF4 can be binded with the WRE functional area of LEF-1 promoter. Nek2B can activite wnt signaling pathway and wnt downstream target genes. The tumors treated by Nek2B siRNA associated with paclitaxel were the smallest in nude mouse, and Nek2B can regulate the expression of β-catenin and wnt downstream target genes in vivo.

Conclusion

Our study suggested that Nek2B can bind to β-catenin and the co-expression correlated with TNBC patients poor prognosis. It appears that Nek2B and β-catenin might synergize to promote chemotherapy resistance.