A two-gene epigenetic signature for the prediction of response to neoadjuvant chemotherapy in triple-negative breast cancer patients

Targeting Triple-Negative Breast Cancer: Resistance Mechanisms and Therapeutic Advancements

BACKGROUND

Triple-negative breast cancer (TNBC) is one of the most heterogeneous and menacing forms of breast cancer, with no sustainable cure available in the current treatment landscape. Its lack of targets makes it highly unresponsive to various treatment modalities, which is why chemotherapy continues to be the primary form of treatment, despite the high rates of patients developing chemoresistance. In recent years, however, there has been significant progress in identifying and understanding the role of several aspects that might contribute to genomic instability and other hallmarks of cancer, including cellular proteins, immune targets, and epigenetic mechanisms, which are desirable as they permit reversibility easier than the often-adamant genetic changes.

METHODS

A literature review was conducted on the role of various TNBC associated biomarkers, their therapeutic applications, and their role in tumorigenesis and tumor maintenance, with a focus on linking both the driving biological mechanisms and emerging treatment options for TNBC.

CONCLUSIONS

Shifting the focus of treatment to identify crucial tumor cell subpopulations and associated biomarkers, such as local immune cell populations and cancer stem cells, could potentially solve or simplify decades' worth of problems that are associated with TNBC, bolstering early detection and the evolution of precision medicine and treatment. The techniques that can be used here are epigenetic analysis and RNA sequencing. Biomarkers, such as PD-L1, survivin, and ABC transporters, are implicated in several crucial processes that maintain tumors, such as cell proliferation, metastasis, immunosuppression, and stemness. Complex treatment options such as, immunotherapy, pathway inhibition, PARP inhibition, virotherapy, and RNA targeting have been considered for TNBC. Phytochemicals are also being considered as a treatment modality for TNBC, as a supplement to chemotherapy and radiation therapy, or as sole treatment.

DNA Methylation and Demethylation in Triple-Negative Breast Cancer: Associations with Clinicopathological Characteristics and the Chemotherapy Response

Objectives: Triple-negative breast cancer (TNBC) is an aggressive cancer subtype with limited treatment options due to the absence of estrogen, progesterone receptors, and HER2 expression. This study examined the impact of DNA methylation and demethylation markers in tumor tissues on TNBC patients' response to neoadjuvant chemotherapy (NACT) and analyzed the correlation between 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) and clinicopathological characteristics, offering new insights into the predictive value of these epigenetic markers. Methods: The study included 53 TNBC female patients, 19 of whom received neoadjuvant chemotherapy (NACT) before surgery. Global DNA methylation and demethylation levels were quantified using an ELISA-based method to measure 5-mC and 5-hmC content in DNA isolated from pre-treatment biopsy samples (in patients undergoing NACT) and postoperative tissues (in patients without NACT). Results: In patients who received NACT, those with disease progression had significantly higher pretreatment levels of 5-hmC (p = 0.028) and a trend toward higher 5-mC levels (p = 0.054) compared to those with pathological complete response, partial response, or stable disease. Higher 5-mC and 5-hmC levels were significantly associated with higher tumor grade (p = 0.039 and p = 0.017, respectively). Additionally, a positive correlation was observed between the Ki-67 proliferation marker and both 5-mC (rS = 0.340, p = 0.049) and 5-hmC (rS = 0.341, p = 0.048) levels in postoperative tissues. Conclusions: Our study highlights the potential of global DNA methylation and demethylation markers as predictors of tumor aggressiveness and chemotherapy response in TNBC. Further research in larger cohorts is necessary to validate these markers' prognostic and predictive value.

Hypomethylating agents as emerging therapeutics for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is recognized as the most aggressive subtype of breast cancer. Epigenetic silencing, such as DNA methylation mediated by DNA methyltransferases (DNMTs) plays key roles in TNBC tumorigenesis. Hypomethylating agents (HMAs) such as azacitidine, decitabine, and guadecitabine are key inhibitors of DNMTs, and accumulating evidence has shown their immunogenicity properties. In this review, the efficacy and anti-tumor immune responses triggered by HMAs in TNBC are presented and discussed. Essentially, overexpression of DNMTs is associated with poor prognosis and reduced TNBC survival rates, and these effects are negated by HMAs. In particular, HMAs could reverse epigenetic silencing of tumor suppressor genes and enhance immune recognition of TNBC cells. Clinical trials of HMAs in TNBCs are limited but early-stage trials indicate that HMAs are safe and tolerable. More clinical studies are required to establish the effectiveness of HMAs against the disease, as supported by preclinical data substantiating their effectiveness especially guadecitabine. Future research should focus on optimizing dosing and exploring combinations with immunotherapies to maximize the potential of HMAs in TNBC treatment.

Fetal Mammary Gland Development and Offspring's Breast Cancer Risk in Adulthood

While advancements in early detection and improved access to care have significantly enhanced breast cancer survival rates, the disease remains a significant global malignancy, constituting approximately 12.5% of all new cancer cases and claiming nearly 700,000 lives in 2020. As a result, there is widespread consensus that the most sustainable solution lies in prevention. Indeed, preventive strategies, including lifestyle modifications and research into risk-reducing interventions, offer the potential to address the root causes of noncommunicable diseases such as breast cancer. While conventional wisdom has long attributed established risk factors for breast cancer to age, lifestyle, familial history, and reproductive factors, evidence highlights the maternal environment as a pivotal stage for fetal programming of disease risk, as elucidated in the developmental origins of health and disease (DOHaD) framework. Consequently, a growing body of research has been focused on elucidating epigenomic signatures that influence fetal development while shaping health outcomes and susceptibility to diseases later in life. This review aims to identify fetal mammary developmental genes that have been implicated in breast cancer etiology and the potential interplay of maternal environment in epigenetic programming of breast cancer risk in adulthood.

Epigenetics as a strategic intervention for early diagnosis and combatting glycolyis-induced chemoresistance in gynecologic cancers

Prospective prediction from the Australian Institute of Health and Welfare (AIHW) showed a likely incidence of 1 in 23 women diagnosed with gynaecological malignancy, where the incidence of relapse with a drug-resistant clone poses a significant challenge in dealing with it even after initial treatment. Glucose metabolism has been exploited as a therapeutic target under anti-metabolomic study, but the non-specificity narrowed its applicability in cancer. Novel updates over epigenetics as a target in gynaecological cancer offer a rational idea of using this in the metabolic rewiring in mutated glycolytic flux-induced drug resistance. This review focuses on the application of epigenetic intervention at a diagnostic and therapeutic level to shift the current treatment paradigm of gynaecological cancers from reactive medicine to predictive, preventive, and personalised medicine. It presents the likely epigenetic targets that can be exploited potentially to prevent the therapeutic failure associated with glucose metabolism-induced chemotherapeutic drug resistance.

Serum Extracellular Vesicles Cargo Approach in Bitches with Mammary Tumors

This study investigated serum extracellular vesicles (EVs) in bitches with mammary neoplasms, in order to understand their size, shape, and concentration, as well as their association with tumor malignancy. Thirty bitches were categorized into control (n = 10), mammary tumor grades I and II (GI, n = 13), and grade III (GII, n = 7). Serum was separated from blood collected during mastectomy, and EVs were isolated using size exclusion chromatography. The analysis revealed no significant differences in EV concentrations among groups, with similar concentrations for control, GI, and GII. Ninety-one proteins were identified in EV-enriched samples, with six showing varied abundance across groups. Notably, keratin 18 was highly abundant in GI, while sushi domain-containing protein, EvC ciliary subunit 2, and the joining chain of multimeric IgM and IgA were increased in GII. Additionally, protocadherin 17 and albumin were upregulated in both GI and GII. ROC curves identified potential biomarkers for differentiating tumor grades. Enrichment pathway analysis revealed AFP gene upregulation in the GI. Mass spectrometry proteomics data were deposited in Mendeley Data. The study provides valuable insights into serum EV characterization in bitches, suggesting keratin 18 and protocadherin 17 as potential biomarkers for canine mammary neoplasia, with implications for future diagnostic and therapeutic strategies.

A journey from omics to clinicomics in solid cancers: Success stories and challenges

The word 'cancer' encompasses a heterogenous group of distinct disease types characterized by a spectrum of pathological features, genetic alterations and response to therapies. According to the World Health Organization, cancer is the second leading cause of death worldwide, responsible for one in six deaths and hence imposes a significant burden on global healthcare systems. High-throughput omics technologies combined with advanced imaging tools, have revolutionized our ability to interrogate the molecular landscape of tumors and has provided unprecedented understanding of the disease. Yet, there is a gap between basic research discoveries and their translation into clinically meaningful therapies for improving patient care. To bridge this gap, there is a need to analyse the vast amounts of high dimensional datasets from multi-omics platforms. The integration of multi-omics data with clinical information like patient history, histological examination and imaging has led to the novel concept of clinicomics and may expedite the bench-to-bedside transition in cancer. The journey from omics to clinicomics has gained momentum with development of radiomics which involves extracting quantitative features from medical imaging data with the help of deep learning and artificial intelligence (AI) tools. These features capture detailed information about the tumor's shape, texture, intensity, and spatial distribution. Together, the related fields of multiomics, translational bioinformatics, radiomics and clinicomics may provide evidence-based recommendations tailored to the individual cancer patient's molecular profile and clinical characteristics. In this chapter, we summarize multiomics studies in solid cancers with a specific focus on breast cancer. We also review machine learning and AI based algorithms and their use in cancer diagnosis, subtyping, prognosis and predicting treatment resistance and relapse.

DNA methylation of HOX genes and its clinical implications in cancer

Homeobox (HOX) genes encode highly conserved transcription factors that play vital roles in embryonic development. DNA methylation is a pivotal regulatory epigenetic signaling mark responsible for regulating gene expression. Abnormal DNA methylation is largely associated with the aberrant expression of HOX genes, which is implicated in a broad range of human diseases, including cancer. Numerous studies have clarified the mechanisms of DNA methylation in both physiological and pathological processes. In this review, we focus on how DNA methylation regulates HOX genes and briefly discuss drug development approaches targeting these mechanisms.

Notch-based gene signature for predicting the response to neoadjuvant chemotherapy in triple-negative breast cancer

BACKGROUND

While the efficacy of neoadjuvant chemotherapy (NACT) in treating triple-negative breast cancer (TNBC) is generally accepted, not all patients derive benefit from this preoperative treatment. Presently, there are no validated biomarkers to predict the NACT response, and previous attempts to develop predictive classifiers based on gene expression data have not demonstrated clinical utility. However, predictive models incorporating biological constraints have shown increased robustness and improved performance compared to agnostic classifiers.

METHODS

We used the preoperative transcriptomic profiles from 298 patients with TNBC to train and test a rank-based classifier, k-top scoring pairs, to predict whether the patient will have pathological complete response (pCR) or residual disease (RD) following NACT. To reduce overfitting and enhance the signature's interpretability, we constrained the training process to genes involved in the Notch signaling pathway. Subsequently, we evaluated the signature performance on two independent cohorts with 75 and 71 patients. Finally, we assessed the prognostic value of the signature by examining its association with relapse-free survival (RFS) using Kaplan‒Meier (KM) survival estimates and a multivariate Cox proportional hazards model.

RESULTS

The final signature consists of five gene pairs, whose relative ordering can be predictive of the NACT response. The signature has a robust performance at predicting pCR in TNBC patients with an area under the ROC curve (AUC) of 0.76 and 0.85 in the first and second testing cohorts, respectively, outperforming other gene signatures developed for the same purpose. Additionally, the signature was significantly associated with RFS in an independent TNBC patient cohort even after adjusting for T stage, patient age at the time of diagnosis, type of breast surgery, and menopausal status.

CONCLUSION

We introduce a robust gene signature to predict pathological complete response (pCR) in patients with TNBC. This signature applies easily interpretable, rank-based decision rules to genes regulated by the Notch signaling pathway, a known determinant in breast cancer chemoresistance. The robust predictive and prognostic performance of the signature make it a strong candidate for clinical implementation, aiding in the stratification of TNBC patients undergoing NACT.

Combining the tumor-stroma ratio with tumor-infiltrating lymphocytes improves the prediction of pathological complete response in breast cancer patients

PURPOSE

The tumor-stroma ratio (TSR) is a common histological parameter that measures stromal abundance and is prognostic in breast cancer (BC). However, more evidence is needed on the predictive value of the TSR for the pathological complete response (pCR) to neoadjuvant chemotherapy (NAC). The purpose of this study was to determine the importance of the TSR in predicting pCR in NAC settings.

METHOD

We evaluated the TSR on pretreatment biopsies of 912 BC patients from four independent Chinese hospitals and investigated the potential value of the TSR for predicting pCR. Meanwhile, stromal tumor-infiltrating lymphocytes (sTILs) were assessed, and we evaluated the predictive value of the combination of sTILs and TSR (TSRILs).

RESULTS

Patients with low stroma showed a higher pCR rate than those with high stroma among the four independent hospitals, and in multivariate analysis, the TSR was proven to be an independent predictor for pCR to NAC with an odds ratio of 1.945 (95% CI 1.230-3.075, P = 0.004). Moreover, we found that TSRILs could improve the area under the curve (AUC) for predicting pCR from 0.750 to 0.785 (P = 0.039); especially in HER2-negative BCs, the inclusion of TSRILs increased the AUC from 0.801 to 0.835 in the discovery dataset (P = 0.048) and 0.734 to 0.801 in the validation dataset (P = 0.003).

CONCLUSION

TSR and sTILs can be easily measured in pathological routines and provide predictive information without additional cost; with more evidence from clinical trials, TSRILs could be a candidate to better stratify patients in NAC settings.

Omics Technologies Improving Breast Cancer Research and Diagnostics

Breast cancer (BC) has yielded approximately 2.26 million new cases and has caused nearly 685,000 deaths worldwide in the last two years, making it the most common diagnosed cancer type in the world. BC is an intricate ecosystem formed by both the tumor microenvironment and malignant cells, and its heterogeneity impacts the response to treatment. Biomedical research has entered the era of massive omics data thanks to the high-throughput sequencing revolution, quick progress and widespread adoption. These technologies-liquid biopsy, transcriptomics, epigenomics, proteomics, metabolomics, pharmaco-omics and artificial intelligence imaging-could help researchers and clinicians to better understand the formation and evolution of BC. This review focuses on the findings of recent multi-omics-based research that has been applied to BC research, with an introduction to every omics technique and their applications for the different BC phenotypes, biomarkers, target therapies, diagnosis, treatment and prognosis, to provide a comprehensive overview of the possibilities of BC research.

DNA Methylation and Prospects for Predicting the Therapeutic Effect of Neoadjuvant Chemotherapy for Triple-Negative and Luminal B Breast Cancer

Despite advances in the diagnosis and treatment of breast cancer (BC), the main cause of deaths is resistance to existing therapies. An approach to improve the effectiveness of therapy in patients with aggressive BC subtypes is neoadjuvant chemotherapy (NACT). Yet, the response to NACT for aggressive subtypes is less than 65% according to large clinical trials. An obvious fact is the lack of biomarkers predicting the therapeutic effect of NACT. In a search for epigenetic markers, we performed genome-wide differential methylation screening by XmaI-RRBS in cohorts of NACT responders and nonresponders, for triple-negative (TN) and luminal B tumors. The predictive potential of the most discriminative loci was further assessed in independent cohorts by methylation-sensitive restriction enzyme quantitative PCR (MSRE-qPCR), a promising method for the implementation of DNA methylation markers in diagnostic laboratories. The selected most informative individual markers were combined into panels demonstrating cvAUC = 0.83 (TMEM132D and MYO15B markers panel) for TN tumors and cvAUC = 0.76 (TTC34, LTBR and CLEC14A) for luminal B tumors. The combination of methylation markers with clinical features that correlate with NACT effect (clinical stage for TN and lymph node status for luminal B tumors) produces better classifiers, with cvAUC = 0.87 for TN tumors and cvAUC = 0.83 for luminal B tumors. Thus, clinical characteristics predictive of NACT response are independently additive to the epigenetic classifier and in combination improve prediction.

DNA methylation biomarkers for noninvasive detection of triple-negative breast cancer using liquid biopsy

Noninvasive detection of aberrant DNA methylation could provide invaluable biomarkers for earlier detection of triple-negative breast cancer (TNBC) which could help clinicians with easier and more efficient treatment options. We evaluated genome-wide DNA methylation data derived from TNBC and normal breast tissues, peripheral blood of TNBC cases and controls and reference samples of sorted blood and mammary cells. Differentially methylated regions (DMRs) between TNBC and normal breast tissues were stringently selected, verified and externally validated. A machine-learning algorithm was applied to select the top DMRs, which then were evaluated on plasma-derived circulating cell-free DNA (cfDNA) samples of TNBC patients and healthy controls. We identified 23 DMRs accounting for the methylation profile of blood cells and reference mammary cells and then selected six top DMRs for cfDNA analysis. We quantified un-/methylated copies of these DMRs by droplet digital PCR analysis in a plasma test set from TNBC patients and healthy controls and confirmed our findings obtained on tissues. Differential cfDNA methylation was confirmed in an independent validation set of plasma samples. A methylation score combining signatures of the top three DMRs overlapping with the SPAG6, LINC10606 and TBCD/ZNF750 genes had the best capability to discriminate TNBC patients from controls (AUC = 0.78 in the test set and AUC = 0.74 in validation set). Our findings demonstrate the usefulness of cfDNA-based methylation signatures as noninvasive liquid biopsy markers for the diagnosis of TNBC.

Potential Impact of Preoperative Circulating Biomarkers on Individual Escalating/de-Escalating Strategies in Early Breast Cancer

The research on non-invasive circulating biomarkers to guide clinical decision is in wide expansion, including the earliest disease settings. Several new intensification/de-intensification strategies are approaching clinical practice, personalizing the treatment for each patient. Moreover, liquid biopsy is revealing its potential with multiple techniques and studies available on circulating biomarkers in the preoperative phase. Inflammatory circulating cells, circulating tumor cells (CTCs), cell-free DNA (cfDNA), circulating tumor DNA (ctDNA), and other biological biomarkers are improving the armamentarium for treatment selection. Defining the escalation and de-escalation of treatments is a mainstay of personalized medicine in early breast cancer. In this review, we delineate the studies investigating the possible application of these non-invasive tools to give a more enlightened approach to escalating/de-escalating strategies in early breast cancer.

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.

Integrated proteomics and phosphoproteomics revealed druggable kinases in neoadjuvant chemotherapy resistant tongue cancer

Tongue squamous cell carcinoma is an aggressive oral cancer with a high incidence of metastasis and poor prognosis. Most of the oral cavity cancer patients present in clinics with locally advanced unresectable tumors. Neoadjuvant treatment is beneficial for these individuals as it reduces the tumor size aiding complete resection. However, patients develop therapy resistance to the drug regimen. In this study, we explored the differential expression of proteins and altered phosphorylation in the neoadjuvant chemotherapy resistant tongue cancer patients. We integrated the proteomic and phosphoproteomic profiles of resistant (n = 4) and sensitive cohorts (n = 4) and demonstrated the differential expression and phosphorylation of proteins in the primary tissue of the respective subject groups. We observed differential and extensive phosphorylation of keratins such as KRT10 and KRT1 between the two cohorts. Furthermore, our study revealed a kinase signature associated with neoadjuvant chemotherapy resistance. Kinases such as MAPK1, AKT1, and MAPK3 are predicted to regulate the resistance in non-responders. Pathway analysis showed enrichment of Rho GTPase signaling and hyperphosphosphorylation of proteins involved in cell motility, invasion, and drug resistance. Targeting the kinases could help with the clinical management of neoadjuvant chemotherapy-resistant tongue cancer.

A genome-wide cell-free DNA methylation analysis identifies an episignature associated with metastatic luminal B breast cancer

Breast cancers of the luminal B subtype are frequent tumors with high proliferation and poor prognosis. Epigenetic alterations have been found in breast tumors and in biological fluids. We aimed to profile the cell-free DNA (cfDNA) methylome of metastatic luminal B breast cancer (LBBC) patients using an epigenomic approach to discover potential noninvasive biomarkers. Plasma cfDNA was analyzed using the Infinium MethylationEpic array in a cohort of 14 women, including metastatic LBBC patients and nontumor controls. The methylation levels of cfDNA and tissue samples were validated with droplet digital PCR. The methylation and gene expression data of 582 primary luminal breast tumors and 79 nontumor tissues were obtained from The Cancer Genome Atlas (TCGA). We found an episignature of 1,467 differentially methylated CpGs that clearly identified patients with LBBC. Among the genes identified, the promoter hypermethylation of WNT1 was validated in cfDNA, showing an area under the ROC curve (AUC) of 0.86 for the noninvasive detection of metastatic LBBC. Both paired cfDNA and primary/metastatic breast tumor samples showed hypermethylation of WNT1. TCGA analysis revealed significant WNT1 hypermethylation in the primary tumors of luminal breast cancer patients, with a negative association between WNT1 methylation and gene expression. In this proof-of-principle study, we discovered an episignature associated with metastatic LBBC using a genome-wide cfDNA methylation approach. We also identified the promoter hypermethylation of WNT1 in cfDNA as a potential noninvasive biomarker for luminal breast cancer. Our results support the use of EPIC arrays to identify new epigenetic noninvasive biomarkers in breast cancer.

Triple negative breast cancer (TNBC): Non-genetic tumor heterogeneity and immune microenvironment: Emerging treatment options

Triple-negative breast cancer (TNBC) is an aggressive subtype characterized by extensive intra-tumoral heterogeneity, and frequently develops resistance to therapies. Tumor heterogeneity and lack of biomarkers are thought to be some of the most difficult challenges driving therapeutic resistance and relapse. This review will summarize current therapy for TNBC, studies in treatment resistance and relapse, including data from recent single cell sequencing. We will discuss changes in both the transcriptome and epigenome of TNBC, and we will review mechanisms regulating the immune microenvironment. Lastly, we will provide new perspective in patient stratification, and treatment options targeting transcriptome dysregulation and the immune microenvironment of TNBC patients.

An Integrative Clinical Model for the Prediction of Pathological Complete Response in Patients with Operable Stage II and Stage III Triple-Negative Breast Cancer Receiving Neoadjuvant Chemotherapy

Simple Summary

Neoadjuvant chemotherapy (NAC) is widely used to treat stage II and III primary, operable triple-negative breast cancer (TNBC). The response to NAC critically affects the subsequent treatment plan, including not only curative surgical planning but also adjuvant therapy. There is no standard prediction model that accurately predicts NAC response. Therefore, the development of an easy-to-apply and cost-effective clinical prediction model for NAC treatment response would improve clinical practice. We propose an integrative clinical prediction model for the prediction of pathologically complete response in patients with operable stage II and stage III TNBC receiving NAC based on findings from tumor ultrasound and blood tests. All included parameters were readily available during and before NAC. This clinical prediction model could provide a reference to guide clinicians’ decisions in planning a patient’s NAC treatment as early as after the first cycle of NAC.

Abstract

Triple-negative breast cancer (TNBC) is treated with neoadjuvant chemotherapy (NAC). The response to NAC, particularly the probability of a complete pathological response (pCR), guides the surgical approach and adjuvant therapy. We developed a prediction model using a nomogram integrating blood tests and pre-treatment ultrasound findings for predicting pCR in patients with stage II or III operable TNBC receiving NAC. Clinical data before and after the first cycle of NAC collected from patients between 2012 and 2019 were analyzed using univariate and multivariate analyses to identify correlations with pCR. The coefficients of the significant parameters were calculated using logistic regression, and a nomogram was developed based on the logistic model to predict the probability of pCR. Eighty-eight patients were included. Five parameters correlated with the probability of pCR, including the neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte (PLR) ratio, percentage change in PLR, presence of echogenic halo, and tumor height-to-width ratio. The discrimination performance of the nomogram was indicated by an area under the curve of 87.7%, and internal validation showed that the chi-square value of the Hosmer–Lemeshow test was 7.67 (p = 0.363). Thus, the integrative prediction model using clinical data can predict the probability of pCR in patients with TNBC receiving NAC.

DNA methylation changes in response to neoadjuvant chemotherapy are associated with breast cancer survival

BACKGROUND

Locally advanced breast cancer is a heterogeneous disease with respect to response to neoadjuvant chemotherapy (NACT) and survival. It is currently not possible to accurately predict who will benefit from the specific types of NACT. DNA methylation is an epigenetic mechanism known to play an important role in regulating gene expression and may serve as a biomarker for treatment response and survival. We investigated the potential role of DNA methylation as a prognostic marker for long-term survival (> 5 years) after NACT in breast cancer.

METHODS

DNA methylation profiles of pre-treatment (n = 55) and post-treatment (n = 75) biopsies from 83 women with locally advanced breast cancer were investigated using the Illumina HumanMethylation450 BeadChip. The patients received neoadjuvant treatment with epirubicin and/or paclitaxel. Linear mixed models were used to associate DNA methylation to treatment response and survival based on clinical response to NACT (partial response or stable disease) and 5-year survival, respectively. LASSO regression was performed to identify a risk score based on the statistically significant methylation sites and Kaplan-Meier curve analysis was used to estimate survival probabilities using ten years of survival follow-up data. The risk score developed in our discovery cohort was validated in an independent validation cohort consisting of paired pre-treatment and post-treatment biopsies from 85 women with locally advanced breast cancer. Patients included in the validation cohort were treated with either doxorubicin or 5-FU and mitomycin NACT.

RESULTS

DNA methylation patterns changed from before to after NACT in 5-year survivors, while no significant changes were observed in non-survivors or related to treatment response. DNA methylation changes included an overall loss of methylation at CpG islands and gain of methylation in non-CpG islands, and these changes affected genes linked to transcription factor activity, cell adhesion and immune functions. A risk score was developed based on four methylation sites which successfully predicted long-term survival in our cohort (p = 0.0034) and in an independent validation cohort (p = 0.049).

CONCLUSION

Our results demonstrate that DNA methylation patterns in breast tumors change in response to NACT. These changes in DNA methylation show potential as prognostic biomarkers for breast cancer survival.

The early-stage triple-negative breast cancer landscape derives a novel prognostic signature and therapeutic target

PURPOSE

Triple-negative breast cancer (TNBC) is a highly heterogeneous disease. Patients with early-stage TNBCs have distinct likelihood of distant recurrence. This study aimed to develop a prognostic signature of early-stage TNBC patients to improve risk stratification.

METHODS

Using RNA-sequencing data, we analyzed 189 pathologically confirmed pT1-2N0M0 TNBC patients and identified 21 mRNAs that were highly expressed in tumor and related to relapse-free survival. All-subset regression program was used for constructing a 7-mRNA signature in the training set (n = 159); the accuracy and prognostic value were then validated using an independent validation set (n = 158).

RESULTS

Here, we profiled the transcriptome data from 189 early-stage TNBC patients along with 50 paired normal tissues. Early-stage TNBCs mainly consisted of basal-like immune-suppressed subtype and had higher homologous recombination deficiency scores. We developed a prognostic signature including seven mRNAs (ACAN, KRT5, TMEM101, LCA5, RPP40, LAGE3, CDKL2). In both the training (n = 159) and validation set (n = 158), this signature could identify patients with relatively high recurrence risks and served as an independent prognostic factor. Time-dependent receiver operating curve showed that the signature had better prognostic value than traditional clinicopathological features in both sets. Functionally, we showed that TMEM101 promoted cell proliferation and migration in vitro, which represented a potential therapeutic target.

CONCLUSIONS

Our 7-mRNA signature could accurately predict recurrence risks of early-stage TNBCs. This model may facilitate personalized therapy decision-making for early-stage TNBCs individuals.

Epigenetic Therapies and Biomarkers in Breast Cancer

Epigenetic therapies remain a promising, but still not widely used, approach in the management of patients with cancer. To date, the efficacy and use of epigenetic therapies has been demonstrated primarily in the management of haematological malignancies, with limited supportive data in solid malignancies. The most studied epigenetic therapies in breast cancer are those that target DNA methylation and histone modification; however, none have been approved for routine clinical use. The majority of pre-clinical and clinical studies have focused on triple negative breast cancer (TNBC) and hormone-receptor positive breast cancer. Even though the use of epigenetic therapies alone in the treatment of breast cancer has not shown significant clinical benefit, these therapies show most promise in use in combinations with other treatments. With improving technologies available to study the epigenetic landscape in cancer, novel epigenetic alterations are increasingly being identified as potential biomarkers of response to conventional and epigenetic therapies. In this review, we describe epigenetic targets and potential epigenetic biomarkers in breast cancer, with a focus on clinical trials of epigenetic therapies. We describe alterations to the epigenetic landscape in breast cancer and in treatment resistance, highlighting mechanisms and potential targets for epigenetic therapies. We provide an updated review on epigenetic therapies in the pre-clinical and clinical setting in breast cancer, with a focus on potential real-world applications. Finally, we report on the potential value of epigenetic biomarkers in diagnosis, prognosis and prediction of response to therapy, to guide and inform the clinical management of breast cancer patients.

Identification of DNA methylation biomarkers with potential to predict response to neoadjuvant chemotherapy in triple-negative breast cancer

Neoadjuvant chemotherapy (NAC) is used to treat triple-negative breast cancer (TNBC) prior to resection. Biomarkers that accurately predict a patient's response to NAC are needed to individualise therapy and avoid chemotoxicity from unnecessary chemotherapy. We performed whole-genome DNA methylation profiling on diagnostic TNBC biopsy samples from the Sequential Evaluation of Tumours Undergoing Preoperative (SETUP) NAC study. We found 9 significantly differentially methylated regions (DMRs) at diagnosis which were associated with response to NAC. We show that 4 of these DMRs are associated with TNBC overall survival (P < 0.05). Our results highlight the potential of DNA methylation biomarkers for predicting NAC response in TNBC.

A novel lncRNA derived from an ultraconserved region: lnc-uc.147, a potential biomarker in luminal A breast cancer

The human genome contains 481 ultraconserved regions (UCRs), which are genomic stretches of over 200 base pairs conserved among human, rat, and mouse. The majority of these regions are transcriptionally active (T-UCRs), and several have been found to be differentially expressed in tumours. Some T-UCRs have been functionally characterized, but of those few have been associated to breast cancer (BC). Using TCGA data, we found 302 T-UCRs related to clinical features in BC: 43% were associated with molecular subtypes, 36% with oestrogen-receptor positivity, 17% with HER2 expression, 12% with stage, and 10% with overall survival. The expression levels of 12 T-UCRs were further analysed in a cohort of 82 Brazilian BC patients using RT-qPCR. We found that uc.147 is high expressed in luminal A and B patients. For luminal A, a subtype usually associated with better prognosis, high uc.147 expression was associated with a poor prognosis and suggested as an independent prognostic factor. The lncRNA from uc.147 (lnc-uc.147) is located in the nucleus. Northern blotting results show that uc.147 is a 2,8 kb monoexonic trancript, and its sequence was confirmed by RACE. The silencing of uc.147 increases apoptosis, arrests cell cycle, and reduces cell viability and colony formation in BC cell lines. Additionally, we identifed 19 proteins that interact with lnc-uc.147 through mass spectrometry and demonstrated a high correlation of lnc-uc.147 with the neighbour gene expression and miR-18 and miR-190b. This is the first study to analyse the expression of all T-UCRs in BC and to functionally assess the lnc-uc.147.

A DNA Methylation-Based Gene Signature Can Predict Triple-Negative Breast Cancer Diagnosis

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer (BC) subtype and lacks targeted treatment. It is diagnosed by the absence of immunohistochemical expression of several biomarkers, but this method still displays some interlaboratory variability. DNA methylome aberrations are common in BC, thereby methylation profiling could provide the identification of accurate TNBC diagnosis biomarkers. Here, we generated a signature of differentially methylated probes with class prediction ability between 5 non-neoplastic breast and 7 TNBC tissues (error rate = 0.083). The robustness of this signature was corroborated in larger cohorts of additional 58 non-neoplastic breast, 93 TNBC, and 150 BC samples from the Gene Expression Omnibus repository, where it yielded an error rate of 0.006. Furthermore, we validated by pyrosequencing the hypomethylation of three out of 34 selected probes (FLJ43663, PBX Homeobox 1 (PBX1), and RAS P21 protein activator 3 (RASA3) in 51 TNBC, even at early stages of the disease. Finally, we found significantly lower methylation levels of FLJ43663 in cell free-DNA from the plasma of six TNBC patients than in 15 healthy donors. In conclusion, we report a novel DNA methylation signature with potential predictive value for TNBC diagnosis.

Molecular Targets and Promising Therapeutics of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is one of the most heterogeneous diseases in solid tumors and has limited therapeutic options. Due to the lack of appropriate targetable markers, the mainstay therapeutic strategy for patients with TNBC has been chemotherapy for the last several decades. Indeed, TNBC tumors have no expression of estrogen receptor, progesterone receptor, or human epidermal growth factor receptor 2 (HER2); therefore, they do not respond to hormone therapy and HER2-targeted therapy. In this review paper, the molecular heterogeneities, possible therapeutic targets, and recently approved and upcoming drugs for TNBC will be summarized.

Deep learning-based predictive biomarker of pathological complete response to neoadjuvant chemotherapy from histological images in breast cancer

Background

Pathological complete response (pCR) is considered a surrogate endpoint for favorable survival in breast cancer patients treated with neoadjuvant chemotherapy (NAC). Predictive biomarkers of treatment response are crucial for guiding treatment decisions. With the hypothesis that histological information on tumor biopsy images could predict NAC response in breast cancer, we proposed a novel deep learning (DL)-based biomarker that predicts pCR from images of hematoxylin and eosin (H&E)-stained tissue and evaluated its predictive performance.

Methods

In total, 540 breast cancer patients receiving standard NAC were enrolled. Based on H&E-stained images, DL methods were employed to automatically identify tumor epithelium and predict pCR by scoring the identified tumor epithelium to produce a histopathological biomarker, the pCR-score. The predictive performance of the pCR-score was assessed and compared with that of conventional biomarkers including stromal tumor-infiltrating lymphocytes (sTILs) and subtype.

Results

The pCR-score derived from H&E staining achieved an area under the curve (AUC) of 0.847 in predicting pCR directly, and achieved accuracy, F1 score, and AUC of 0.853, 0.503, and 0.822 processed by the logistic regression method, respectively, higher than either sTILs or subtype; a prediction model of pCR constructed by integrating sTILs, subtype and pCR-score yielded a mean AUC of 0.890, outperforming the baseline sTIL-subtype model by 0.051 (0.839, P  =  0.001).

Conclusion

The DL-based pCR-score from histological images is predictive of pCR better than sTILs and subtype, and holds the great potentials for a more accurate stratification of patients for NAC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03020-z.

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.

Epigenetic Awakening of Viral Mimicry in Cancer

In this issue, Deblois and colleagues show how taxane-resistant triple-negative breast cancer cells evade viral mimicry response as a result of metabolic alteration, DNA hypomethylation, and relocation of histone H3K27 trimethylation (H3K27me3). This adaptation confers a therapeutic vulnerability to the inhibition of the H3K27me3 methyltransferase EZH2 in resistant cells, leading to tumor growth inhibition by viral mimicry reactivation.See related article by Deblois et al., p. 1312.

Emerging noninvasive methylation biomarkers of cancer prognosis and drug response prediction

Cancer is the second leading cause of death worldwide being responsible for 9.6 million deaths in 2018. Epigenetic alterations are key in directing the aberrant expression of tumor-associated genes that drive cellular malignant transformation and cancer progression. Among epigenetic alterations, DNA methylation is the most deeply studied one in relation to environmental exposure. Tissue biopsies have traditionally been the main procedure by which a small sample of body tissue is excised to confirm cancer diagnosis or to indicate the primary site when cancer has spread. In contrast, the analysis of circulating tumor-derived material, or tumor circulome, by means of liquid biopsy of peripheral blood, urine, saliva or sputum is a noninvasive, fast and reproducible alternative to tissue biopsy. Recently, the assessment of epigenetic alterations such as DNA methylation and hydroxymethylation in circulating free DNA has been proved possible. These marks can be associated to prognosis and response to a variety of treatments including chemotherapy, hormonotherapy or immunotherapy. Epigenetic biomarkers may offer some advantages over RNA or genetic biomarkers given their stability in bodily fluids and their high tissue-specificity. While many challenges are still ahead, the unique advantages of these types of biomarkers is urging the scientific community to persevere in their clinical validation and integration into reliable prediction models. This review aims at recapitulating the emerging noninvasive DNA methylated biomarkers of importance for prediction of prognosis and drug response in cancer.

Potential effects of nutrition-based weight loss therapies in reversing obesity-related breast cancer epigenetic marks

Obesity is a modifiable risk factor of breast cancer and epigenetic marks were proposed as a relevant mechanistic link. These mechanisms can be remodelled by modifying lifestyle factors and this fact could be useful in the treatment of obesity-related breast cancer. This review aimed to reveal the current evidence on the effects of differences in body composition and lifestyle factors on the risk, treatment, and survival of breast cancer with a focus on the effects of weight loss therapies based on different nutrients, bioactive compounds, and Mediterranean and ketogenic diets to counteract obesity-related breast cancer epigenetic marks. This review was framed on the most relevant and recently published articles and abstracts selected in PubMed using key words related to epigenetics, lifestyle, dietary habits, nutrients, bioactive compounds, ketone bodies, and weight loss treatments in obesity and breast cancer. Several studies have demonstrated that lifestyle interventions, including dietary modifications towards a healthy diet pattern, are effective therapies to prevent the onset of breast cancer and to improve the survival after treatment. These therapies reduce the main factors associated with obesity that are links between adiposity and cancer, including oxidative stress, inflammation and epigenetic mechanisms. However, although sufficient evidence exists regarding the effects of nutrients, dietary patterns, and weight loss therapies to prevent breast cancer or to improve survival, the effects of these strategies on the oncological treatment response were less studied. This review summarises the current scientific evidence regarding these nutritional strategies as adjuvant therapies in the management of obesity-related breast cancer by remodelling epigenetic marks related to carcinogenesis.

Ketotherapy as an epigenetic modifier in cancer

Epigenetic alterations in cancer play a variety of roles. Aberrant DNA methylation, as one of the epigenetic mechanisms, has been widely studied in both tumor and liquid biopsies and provide a useful bench mark for treatment response in cancer. Recently, several studies have reported an association between the type of diet and epigenetic modifications. Whereby there is a growing interest in finding the "anti-cancer diet formula", if such a thing exists. In this sense, ketogenic diets (KD) have reported potentially beneficial effects, which were able to prevent malignancies and decrease tumor growth. Some studies have even shown increased survival in cancer patients, reduced side effects of cytotoxic treatments, and intensified efficacy of cancer therapies. Although the biological mechanisms of KD are not well understood, it has been reported that KD may affect DNA methylation by modulating the expression of crucial genes involved in tumor survival and proliferation. However, there are many considerations to take into account to use ketotherapy in cancer, such as epigenetic mark, type of cancer, immunological and metabolic state or microbiota profile. In this review, we argue about ketotherapy as a potential strategy to consider as coadjuvant of cancer therapy. We will focus on mainly epigenetic mechanisms and dietary approach that could be included in the current clinical practice guidelines.

Predicting and Overcoming Taxane Chemoresistance

Taxanes are microtubule-targeting drugs used as cytotoxic chemotherapy to treat most solid tumors. The development of resistance to taxanes is a major cause of therapeutic failure and overcoming chemoresistance remains an important challenge to improve patient's outcome. Extensive efforts have been made recently to identify predictive biomarkers to select populations of patients who will benefit from taxane-based chemotherapy and avoid inefficient treatment of patients with innate resistance. This, together with the discovery of new mechanisms of resistance that include metabolic reprogramming and dialogue between tumor and its microenvironment, pave the way to a new era of personalized medicine. In this review, we recapitulate recent insights into taxane resistance and present promising emerging strategies to overcome chemoresistance in the future.

Biology of the Triple-Negative Breast Cancer: Immunohistochemical, RNA, and DNA Features

Background

The triple-negative breast cancer (TNBC) constitutes a heterogeneous disease with an aggressive behavior and a poor prognosis. A better understanding of its biology is required to identify new biomarkers and improve clinical outcomes.

Summary

To date, the definition and classification of TNBC depends on a multiomic approach including immunohistochemistry (IHC), genomic, and transcriptomic features, and the tumor immune landscape. The development of new technologies has allowed us to sequence the whole cancer genome. The Cancer Genome Atlas (TCGA) and next-generation sequencing have led to a greater knowledge of DNA alterations such as TP53 or BRCA mutations, copy number variations, and DNA methylations. In addition, gene expression profiling has allowed to define a molecular intrinsic classification of TNBC based on mRNA. IHC and genomic profiling are also necessary to identify new immune biomarkers such as the presence of tumor-infiltrating lymphocytes and the expression of immune checkpoint molecules.

Key Messages

This review aimed to provide recent knowledge of TNBC biology and classification focused on IHC, transcriptomics, genomic features, and the new immune biomarkers.

Genomic landscape of metastatic breast cancer identifies preferentially dysregulated pathways and targets

Nearly all breast cancer deaths result from metastatic disease. Despite this, the genomic events that drive metastatic recurrence are poorly understood. We performed whole-exome and shallow whole-genome sequencing to identify genes and pathways preferentially mutated or copy-number altered in metastases compared with the paired primary tumors from which they arose. Seven genes were preferentially mutated in metastases - MYLK, PEAK1, SLC2A4RG, EVC2, XIRP2, PALB2, and ESR1 - 5 of which are not significantly mutated in any type of human primary cancer. Four regions were preferentially copy-number altered: loss of STK11 and CDKN2A/B, as well as gain of PTK6 and the membrane-bound progesterone receptor, PAQR8. PAQR8 gain was mutually exclusive with mutations in the nuclear estrogen and progesterone receptors, suggesting a role in treatment resistance. Several pathways were preferentially mutated or altered in metastases, including mTOR, CDK/RB, cAMP/PKA, WNT, HKMT, and focal adhesion. Immunohistochemical analyses revealed that metastases preferentially inactivate pRB, upregulate the mTORC1 and WNT signaling pathways, and exhibit nuclear localization of activated PKA. Our findings identify multiple therapeutic targets in metastatic recurrence that are not significantly mutated in primary cancers, implicate membrane progesterone signaling and nuclear PKA in metastatic recurrence, and provide genomic bases for the efficacy of mTORC1, CDK4/6, and PARP inhibitors in metastatic breast cancer.

Resistance to Neoadjuvant Treatment in Breast Cancer: Clinicopathological and Molecular Predictors

Neoadjuvant Chemotherapy (NAC) in Breast Cancer (BC) has proved useful for the reduction in tumor burden prior to surgery, allowing for a more extensive breast preservation and the eradication of subjacent micrometastases. However, the impact on prognosis is highly dependent on the establishment of Pathological Complete Response (pCR), in particular for Triple Negative (TN) and Hormonal Receptor negative/Human Epidermal growth factor Receptor 2 positive (HR-/HER2+) subtypes. Several pCR predictors, such as PAM50, Integrative Cluster (IntClust), mutations in PI3KCA, or the Trastuzumab Risk model (TRAR), are useful molecular tools for estimating response to treatment and are prognostic. Major evolution events during BC NAC that feature the Residual Disease (RD) are the loss of HR and HER2, which are prognostic of bad outcome, and stemness and immune depletion-related gene expression aberrations. This dynamic nature of the determinants of response to BC NAC, together with the extensive heterogeneity of BC, raises the need to discern the individual and subtype-specific determinants of resistance. Moreover, refining the current approaches for a comprehensive monitoring of tumor evolution during treatment, RD, and eventual recurrences is essential for identifying new actionable alterations and the integral best management of the disease.

Methylation in HOX Clusters and Its Applications in Cancer Therapy

HOX genes are commonly known for their role in embryonic development, defining the positional identity of most structures along the anterior–posterior axis. In postembryonic life, HOX gene aberrant expression can affect several processes involved in tumorigenesis such as proliferation, apoptosis, migration and invasion. Epigenetic modifications are implicated in gene expression deregulation, and it is accepted that methylation events affecting HOX gene expression play crucial roles in tumorigenesis. In fact, specific methylation profiles in the HOX gene sequence or in HOX-associated histones are recognized as potential biomarkers in several cancers, helping in the prediction of disease outcomes and adding information for decisions regarding the patient’s treatment. The methylation of some HOX genes can be associated with chemotherapy resistance, and its identification may suggest the use of other treatment options. The use of epigenetic drugs affecting generalized or specific DNA methylation profiles, an approach that now deserves much attention, seems likely to be a promising weapon in cancer therapy in the near future. In this review, we summarize these topics, focusing particularly on how the regulation of epigenetic processes may be used in cancer therapy.

Epigenetics of Circulating Tumor Cells in Breast Cancer

Liquid biopsy based on the analysis of circulating tumor cells (CTCs) has emerged as an important field of research. Molecular characterization of CTCs can provide insights into cancer biology and biomarkers for the clinic, representing a non-invasive powerful tool for monitoring breast cancer metastasis and predict the therapeutic response. Epigenetic mechanisms play a key role in the control of gene expression and their alteration contributes to cancer development and progression. These epigenetic modifications in CTCs have been described mainly related to modifications of the DNA methylation pattern and changes in the expression profile of noncoding RNAs. Here we summarize the recent findings on the epigenetic characterization of CTCs in breast cancer and their clinical value as tumor biomarkers, and discuss challenges and opportunities in this field.

HOX genes function in Breast Cancer development

Breast cancer develops in the mammary glands during mammalian adulthood and is considered the second most common type of human carcinoma and the most incident and mortal in the female population. In contrast to other human structures, the female mammary glands continue to develop after birth, undergoing various modifications during pregnancy, lactation and involution under the regulation of hormones and transcription factors, including those encoded by the HOX clusters (A, B, C, and D). Interestingly, HOX gene deregulation is often associated to breast cancer development. Within the HOXB cluster, 8 out of the 10 genes present altered expression levels in breast cancer with an impact in its aggressiveness and resistance to hormone therapy, which highlights the importance of HOXB genes as potential therapeutic targets used to overcome the limitations of tamoxifen-resistant cancer treatments. Here, we review the current state of knowledge on the role of HOX genes in breast cancer, specially focus on HOXB, discussing the causes and consequences of HOXB gene deregulation and their relevance as prognostic factors and therapeutic targets.

ADAM12 is A Potential Therapeutic Target Regulated by Hypomethylation in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype and currently lacks any effective targeted therapy. Since epigenetic alterations are a common event in TNBC, DNA methylation profiling can be useful for identifying potential biomarkers and therapeutic targets. Here, genome-wide DNA methylation from eight TNBC and six non-neoplastic tissues was analysed using Illumina Human Methylation 450K BeadChip. Results were validated by pyrosequencing in an independent cohort of 50 TNBC and 24 non-neoplastic samples, where protein expression was also assessed by immunohistochemistry. The functional role of disintegrin and metalloproteinase domain-containing protein 12(ADAM12) in TNBC cell proliferation, migration and drug response was analysed by gene expression silencing with short hairpin RNA. Three genes (Von Willenbrand factor C and Epidermal Growth Factor domain-containing protein (VWCE), tetraspanin-9 (TSPAN9) and ADAM12) were found to be exclusively hypomethylated in TNBC. Furthermore, ADAM12 hypomethylation was associated with a worse outcome in TNBC tissues and was also found in adjacent-to-tumour tissue and, preliminarily, in plasma from TNBC patients. In addition, ADAM12 silencing decreased TNBC cell proliferation and migration and improved doxorubicin sensitivity in TNBC cells. Our results indicate that ADAM12 is a potential therapeutic target and its hypomethylation could be a poor outcome biomarker in TNBC.

Stearoyl-CoA desaturase (scd1a) is epigenetically regulated by broodstock nutrition in gilthead sea bream (Sparus aurata)

The aim of this study was to generate new knowledge on fish epigenetics, assessing the effects of linolenic acid (ALA) conditioning of broodstock in the offspring of the marine fish Sparus aurata. Attention was focused on gene organization, methylation signatures and gene expression patterns of fatty acid desaturase 2 (fads2) and stearoyl-CoA desaturase 1a (scd1a). Blat searches in the genomic IATS-CSIC database (www.nutrigroup-iats.org/seabreamdb) highlighted a conserved exon-intron organization, a conserved PUFA response region, and CG islands at the promoter regions of each gene. The analysed CpG positions in the fads2 promoter were mostly hypomethylated and refractory to broodstock nutrition. The same response was achieved after conditioning of juvenile fish to low water oxygen concentrations, thus methylation susceptibility at individual CpG sites seems to be stringently regulated in fish of different origin and growth trajectories. Conversely, the scd1a promoter was responsive to broodstock nutrition and the offspring of parents fed the ALA-rich diet shared an increased DNA-methylation, mainly in CpG sites neighbouring SP1 and HNF4α binding sites. Cytosine methylation at these sites correlated inversely with the hepatic scd1a expression of the offspring. Co-expression analyses supported that the HNF4α-dependent regulation of scd1a is affected by DNA methylation. The phenotypic output is a regulated liver fat deposition through changes in scd1 expression, which would also allow the preservation of fatty acid unsaturation levels in fish fed reduced levels of n-3 LC-PUFA. Collectively, these findings reveal a reliable mechanism by which parent's nutrition can shape scd1a gene expression in the fish offspring.

Nanoparticles-based drug delivery and gene therapy for breast cancer: Recent advancements and future challenges

Breast cancer (BC) is amongst the most lethal cancer among females and conventional treatment methods like surgery, radiotherapy and chemotherapy are not effective enough as expected and suffer concerns of low bioavailability, low cellular uptake, emerging resistance, and adverse toxicities. Gene therapy using free nucleic acids has potential to deal with key candidate genes of BC, but their effect is retarded due to poor cell uptake and instability in circulation. The rapidly evolving field of nanomedicine aiming targeted drug/gene delivery curtailing BC promises to overcome the limitations of conventional therapies. Nanoparticles can be game changer for BC gene therapy as they can be effective carrier of specific drug/gene by improving the circulation time, enhancing bioavailability, reducing the immune system based recognition chances, and delivering the gene regulator accurately. Herein, we discuss the mechanism of nanoparticles targeted drug delivery, recent advancement of therapeutic strategies of nanoparticles based carriers for small interfering RNA, and microRNA, and gene augmentation therapies in BC. We also discuss the future prospect and challenges of nanoparticle-based therapies for BC.

The Altered Transcriptome and DNA Methylation Profiles of Docetaxel Resistance in Breast Cancer PDX Models

Taxanes are standard therapy in clinical practice for metastatic breast cancer; however, primary or acquired chemoresistance are a common cause of mortality. Breast cancer patient-derived xenografts (PDX) are powerful tools for the study of cancer biology and drug treatment response. Specific DNA methylation patterns have been associated to different breast cancer subtypes but its association with chemoresistance remains unstudied. Aiming to elucidate docetaxel resistance mechanisms, we performed genome-wide DNA methylation in breast cancer PDX models, including luminal and triple-negative breast cancer (TNBC) models sensitive to docetaxel, their matched models after emergence of chemoresistance and residual disease after short-term docetaxel treatment. We found that DNA methylation profiles from breast cancer PDX models maintain the subtype-specific methylation patterns of clinical samples. Two main DNA methylation clusters were found in TNBC PDX and remain stable during the emergence of docetaxel resistance; however, some genes/pathways were differentially methylated according to docetaxel response. A DNA methylation signature of resistance able to segregate TNBC based on chemotherapy response was identified. Transcriptomic profiling of selected sensitive/resistant pairs and integrative analysis with methylation data demonstrated correlation between some differentially methylated and expressed genes in docetaxel-resistant TNBC PDX models. Multiple gene expression changes were found after the emergence of docetaxel resistance in TNBC. DNA methylation and transcriptional changes identified between docetaxel-sensitive and -resistant TNBC PDX models or residual disease may have predictive value for chemotherapy response in TNBC. IMPLICATIONS: Subtype-specific DNA methylation patterns are maintained in breast cancer PDX models. While no global methylation changes were found, we uncovered differentially DNA methylated and expressed genes/pathways associated with the emergence of docetaxel resistance in TNBC.