Accurate prediction of response to endocrine therapy in breast cancer patients: current and future biomarkers

Emerging therapeutic strategies and opportunities in targeting protein pathways for breast cancer treatment: a critical review

Understanding breast cancer at a molecular level is essential for developing effective treatments due to its significant impact on women's mortality rates globally. Targeted medicines focus on specific proteins crucial to breast cancer progression, offering a promising treatment avenue. These proteins, often overexpressed or mutated in cancer cells, are vital for cell proliferation, division, and survival. Targeted drugs aim to inhibit these proteins, halting disease progression and sparing non-cancerous cells, which reduces side effects and improves patient quality of life. Key proteins in breast cancer treatment include HER2 (human epidermal growth factor receptor 2), ER (estrogen receptor), and PR (progesterone receptor). Drugs like Trastuzumab target HER2 to impede tumor growth in HER2-positive cancers, while hormone therapies targeting ER and PR improve outcomes for hormone receptor-positive cancers. Examining proteins such as EGFR, HER2/Neu, and ER reveals their roles in cancer pathways, with pathways like PI3K/Akt/mTOR (phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin) and MAPK (mitogen-activated protein kinase) being crucial targets for therapies, potentially revolutionizing breast cancer treatment.

Radiogenomic Landscape of Metastatic Endocrine-Positive Breast Cancer Resistant to Aromatase Inhibitors

Breast cancer poses a significant global health challenge and includes various subtypes, such as endocrine-positive, HER2-positive, and triple-negative. Endocrine-positive breast cancer, characterized by estrogen and progesterone receptors, is commonly treated with aromatase inhibitors. However, resistance to these inhibitors can hinder patient outcomes due to genetic and epigenetic alterations, mutations in the estrogen receptor 1 gene, and changes in signaling pathways. Radiogenomics combines imaging techniques like MRI and CT scans with genomic profiling methods to identify radiographic biomarkers associated with resistance. This approach enhances our understanding of resistance mechanisms and metastasis patterns, linking them to specific genomic profiles and common metastasis sites like the bone and brain. By integrating radiogenomic data, personalized treatment strategies can be developed, improving predictive and prognostic capabilities. Advancements in imaging and genomic technologies offer promising avenues for enhancing radiogenomic research. A thorough understanding of resistance mechanisms is crucial for developing effective treatment strategies, making radiogenomics a valuable integrative approach in personalized medicine that aims to improve clinical outcomes for patients with metastatic endocrine-positive breast cancer.

Genomic hallmarks of endocrine therapy resistance in ER/PR+HER2- breast tumours

ER/PR+HER2- breast tumours are the most predominant subtype of breast cancer worldwide, including India. Unlike TNBCs, these tumours can be treated with anti-estrogens or aromatase inhibitors. Despite the success of endocrine therapy, a fraction of patients with ER/PR+ breast tumours do not respond to hormone-receptor-specific treatment and encounter disease recurrence contributing to their poor survival. The genomic underpinnings of therapy resistance in ER/PR+HER2- breast tumours are incompletely understood. We have performed whole genome sequencing (WGS) from tumour and normal tissue samples from endocrine-therapy resistant ER/PR+HER2- breast cancer patients who have relapsed on endocrine therapy and have conducted a comparative analysis of WGS data generated from tissues of endocrine therapy sensitive patients who remained free of disease during a minimum 5-year follow-up. Our analysis shows (a) a three-gene (PIK3CA-ESR1-TP53) resistance signature, and (b) impaired DNA double-strand break repair and homologous recombination pathways, were significantly associated with endocrine-therapy resistance and disease recurrence in ER/PR+HER2- tumours. Genome instability, contributing to high burden of copy-number, structural alterations and telomere-shortening identified as major markers of endocrine treatment resistance. Early prediction of endocrine-therapy resistance from the genomic landscape of breast tumours will aid therapeutics. Our finding also opens up the possibility of repurposing PARP inhibitors in treating endocrine therapy-resistant breast cancer patients.

Deciphering TGF-β1's role in drug resistance and leveraging plant bioactives for cancer therapy

The intricate regulatory mechanisms governing TGF-β1 expression play pivotal roles in tumor progression. Key proteins such as FKBP1A, SMAD6, and SMAD7 trigger this process, modulating cell growth inhibition via p15INK4b and p21CIP1 induction. Despite TGF-β's tumor-suppressive functions, cancer cells adeptly evade its effects, fueling disease advancement. Tumor microenvironmental TGF-β1 prompts epithelial-mesenchymal transition (EMT), facilitated by transcription factors like slug, twist-1, and snail. Notably, cancer-associated fibroblasts (CAFs) amplify this effect by secreting TGF-β1, fostering drug resistance. Of particular concern is the resistance observed with BRAF/MEK inhibitors (BRAFi/MEKi), highlighting the clinical significance of TGF-β signaling in cancer therapeutics. However, emerging interest in natural anti-cancer agents, with their distinct pharmacological actions on signaling proteins offers promising avenues for therapeutic intervention. This review emphasizes the multifaceted interplay between TGF-β signaling, tumor microenvironment dynamics, and therapeutic resistance mechanisms, illuminating potential targets for combating cancer progression by plant-derived-natural-bioactive compounds. However, this review additionally explores the currently available advanced methods for detecting various types of cancer. Not only that, but it also discussed the function of plant-derived compounds in clinical aspects, as well as its limitations.

Apoptotic effect of melatonin on ER-positive breast cancer cell lines: ADGRL4 gene expression and promoter methylation

Breast cancer (BC) is the second most common malignancy worldwide. ADGRL4, as a modulator of angiogenesis, undergoes various epigenetic modifications affecting its biological functions. In this study, we aimed to assess ADGRL4 promoter methylation status and its expression levels in primary breast tumors and to evaluate its potency as a plausible prognostic biomarker in BC. Furthermore, we evaluated the effect of melatonin on ADGRL4 expression and viability of BC cells in vitro. One hundred breast tumor tissue samples and adjacent non-tumor tissues were collected, followed by DNA isolation, bisulfite conversion, qRT-PCR, qMSP assay, and immunoblotting. In addition, four BC cell lines were treated with melatonin and subjected to ADGRL4 expression analysis and apoptosis assay. We found a significant correlation between ADGRL4 expression levels and HER2 status and stage of disease (P < 0.05). We observed a substantial attenuation in ADGRL4 promoter methylation in tumor samples compared to marginal non-tumor samples. A significantly lower expression of ADGRL4 was detected in two BC cell lines in the presence of melatonin. MCF-7 and BT474 melatonin-treated cell lines showed a significantly higher number of apoptotic cells than non-treated cells (P < 0.0001). Based on the receiver operating characteristic (ROC) curve analysis, ADGRL4 expression and ADGRL4 promoter methylation status showed moderate prognostic value. We found that melatonin has anti-cancer effects on BC cells. In addition, ADGRL4 expression can potentially be used as a prognostic biomarker in BC.

Baseline breast tissue characteristics determine the effect of tamoxifen on mammographic density change

Tamoxifen prevents recurrence of breast cancer and is also approved for preventive, risk-reducing, therapy. Tamoxifen alters the breast tissue composition and decreases the mammographic density. We aimed to test if baseline breast tissue composition influences tamoxifen-associated density change. This biopsy-based study included 83 participants randomised to 6 months daily intake of placebo, 20, 10, 5, 2.5, or 1 mg tamoxifen. The study is nested within the double-blinded tamoxifen dose-determination trial Karolinska Mammography Project for Risk Prediction of Breast Cancer Intervention (KARISMA) Study. Ultrasound-guided core-needle breast biopsies were collected at baseline before starting treatment. Biopsies were quantified for epithelial, stromal, and adipose distributions, and epithelial and stromal expression of proliferation marker Ki67, oestrogen receptor (ER) and progesterone receptor (PR). Mammographic density was measured using STRATUS. We found that greater mammographic density at baseline was positively associated with stromal area and inversely associated with adipose area and stromal expression of ER. Premenopausal women had greater mammographic density and epithelial tissue, and expressed more epithelial Ki67, PR, and stromal PR, compared to postmenopausal women. In women treated with tamoxifen (1-20 mg), greater density decrease was associated with higher baseline density, epithelial Ki67, and stromal PR. Women who responded to tamoxifen with a density decrease had on average 17% higher baseline density and a 2.2-fold higher PR expression compared to non-responders. Our results indicate that features in the normal breast tissue before tamoxifen exposure influences the tamoxifen-associated density decrease, and that the age-associated difference in density change may be related to age-dependant differences in expression of Ki67 and PR.

Exploring novel protein-based biomarkers for advancing breast cancer diagnosis: A review

This review provides a contemporary examination of the evolving landscape of breast cancer (BC) diagnosis, focusing on the pivotal role of novel protein-based biomarkers. The overview begins by elucidating the multifaceted nature of BC, exploring its prevalence, subtypes, and clinical complexities. A critical emphasis is placed on the transformative impact of proteomics, dissecting the proteome to unravel the molecular intricacies of BC. Navigating through various sources of samples crucial for biomarker investigations, the review underscores the significance of robust sample processing methods and their validation in ensuring reliable outcomes. The central theme of the review revolves around the identification and evaluation of novel protein-based biomarkers. Cutting-edge discoveries are summarised, shedding light on emerging biomarkers poised for clinical application. Nevertheless, the review candidly addresses the challenges inherent in biomarker discovery, including issues of standardisation, reproducibility, and the complex heterogeneity of BC. The future direction section envisions innovative strategies and technologies to overcome existing challenges. In conclusion, the review summarises the current state of BC biomarker research, offering insights into the intricacies of proteomic investigations. As precision medicine gains momentum, the integration of novel protein-based biomarkers emerges as a promising avenue for enhancing the accuracy and efficacy of BC diagnosis. This review serves as a compass for researchers and clinicians navigating the evolving landscape of BC biomarker discovery, guiding them toward transformative advancements in diagnostic precision and personalised patient care.

An ESR1-Related Gene Signature Identifies Head and Neck Squamous Cell Carcinoma with Imputed Susceptibility to Endocrine Therapy

Head and neck squamous cell carcinoma (HNSCC) is associated with high morbidity and mortality. New personalized treatment strategies represent an unmet medical need to improve the overall survival and the quality of life of patients, which are often limited by the toxicity of established multimodal treatment protocols. Several studies have reported an increased expression of the estrogen receptor 1 (ESR1) in HNSCC, but its potential role in the disease outcome of these tumors remains elusive. Using an integrative analysis of multiomics and clinical data from The Cancer Genome Atlas (TCGA)-HNSC, we established a prognostic risk model based on an ESR1-related 25-gene set. The prognostic value was confirmed in an independent cohort of HNSCC and other solid tumors from TCGA. Finally, we performed in silico drug sensitivity modeling to explore potential vulnerabilities for both risk groups. This approach predicted a higher sensitivity for HNSCC, with prominent ESR1 pathway activity under treatment with specific estrogen receptor modulators. In conclusion, our data confirm the involvement of ESR1-related pathway activity in the progression of a defined subset of HNSCC, provide compelling evidence that these tumors share a specific vulnerability to endocrine therapy, and pave the way for preclinical studies and clinical trials to demonstrate the efficacy of this new therapeutic option.

From carcinogenesis to therapeutic avenues: lncRNAs and mTOR crosstalk in lung cancer

Long non-coding RNAs (lncRNAs) have been demonstrated to have a crucial function in the modulation of the activity of genes, impacting a variety of homeostatic processes involving growth, survival, movement, and genomic consistency. Certain lncRNAs' aberrant expression has been linked to carcinogenesis, tumor growth, and therapeutic resistance. They are beneficial for the management of malignancies since they can function as cancer-causing or cancer-suppressing genes and behave as screening or prognosis indicators. The modulation of the tumor microenvironment, metabolic modification, and spread have all been linked to lncRNAs in lung cancer. Recent research has indicated that lncRNAs may interact with various mTOR signalling systems to control expression in lung cancer. Furthermore, the route can affect how lncRNAs are expressed. Emphasizing the function of lncRNAs as crucial participants in the mTOR pathway, the current review intends to examine the interactions between the mTOR cascade and the advancement of lung cancer. The article will shed light on the roles and processes of a few lncRNAs associated with the development of lung cancer, as well as their therapeutic prospects.

Characteristics and prognostic significance of polo-like kinase-1 (PLK1) expression in breast cancer

AIM

Polo-like kinase-1 (PLK1) plays a crucial role in cell cycle progression, and it is considered a potential therapeutic target in many cancers. Although the role of PLK1 is well established in triple-negative breast cancer (TNBC) as an oncogene, its role in luminal BC is still controversial. In this study, we aimed to evaluate the prognostic and predictive role of PLK1 in BC and its molecular subtypes.

METHODS

A large BC cohort (n = 1208) were immunohistochemically stained for PLK1. The association with clinicopathological, molecular subtypes, and survival data was analysed. PLK1 mRNA was evaluated in the publicly available datasets (n = 6774), including The Cancer Genome Atlas and the Kaplan-Meier Plotter tool.

RESULTS

20% of the study cohort showed high cytoplasmic PLK1 expression. High PLK1 expression was significantly associated with a better outcome in the whole cohort, luminal BC. In contrast, high PLK1 expression was associated with a poor outcome in TNBC. Multivariate analyses indicated that high PLK1 expression is independently associated with longer survival in luminal BC, and in poorer prognosis in TNBC. At the mRNA levels, PLK1 expression was associated with short survival in TNBC consistent with the protein expression. However, in luminal BC, its prognostic value significantly varies between cohorts.

CONCLUSION

The prognostic role of PLK1 in BC is molecular subtype-dependent. As PLK1 inhibitors are introduced to clinical trials for several cancer types, our study supports evaluation of the pharmacological inhibition of PLK1 as an attractive therapeutic target in TNBC. However, in luminal BC, PLK1 prognostic role remains controversial.

Decoding SEC24 Homolog D, COPII coat complex component accuracy as a signature gene in three human cancers

Although an increasing body of evidence supports the crucial role of the SEC24 Homolog D, COPII Coat Complex Component (SEC24D) gene in the initiation and progression of cancer, a comprehensive pan-cancer analysis of this gene is still lacking. In this study, we conducted an extensive investigation of SEC24D, aiming to elucidate its potential role and underlying mechanisms across multiple human tumors. Our analysis relied on data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. To validate our findings, we employed RNA sequencing (RNA-seq), targeted bisulfite sequencing (bisulfite-seq) molecular techniques. Our findings revealed elevated mRNA (Messenger RNA) and protein levels of SEC24D in different tumor tissues. However, the up-regulation of SEC24D was significantly correlated with shorter overall survival (OS), metastasis, and various clinical parameters in esophageal cancer (ESCA), lung adenocarcinoma (LUAD), and kidney renal papillary cell carcinoma (KIRP). Expression validation analysis via RNA-seq and targeted bisulfite-seq analyses, further confirmed the higher expression of SEC24D in LUAD cancer cell lines as compared to normal controls. The DNA methylation level of SEC24D was found to be decreased in ESCA, LUAD, and KIRP samples. DNA methylation analysis via bisulfite-seq analysis also validate the lower promoter methylation level of SE24D in LUAD cell lines relative to controls. Moreover, we observed a significant association between the elevated expression of SEC24D and the levels of infiltrating cells, such as B cells, neutrophils, macrophages, CD8+ T cells, and CD4+ T cells. Analysis of SEC24-related genes revealed that "Protein processing in endoplasmic reticulum, SNARE interaction in vesicular transport, Legionellosis, Pathogenic Escherichia coli infection" were mainly involved in the functional mechanism of SEC24D in ESCA, LUAD, and KIRP. Moreover, we also suggested a few valuable drugs (Acetaminophen, Acteoside, Cyclosporine, Polydatin, Estradiol, Estradiol, Quercetin) for treating ESCA, LUAD, and KIRP patients with respect to overexpressed SEC24D. To summarize, this comprehensive pan-cancer study investigated the association between SEC24D expression and clinical parameters in ESCA, LUAD, KIRP. The study provides valuable insights for further exploring the functional and therapeutic aspects of SEC24D and underscores its predictive significance in the carcinogenesis and prognosis of these specific cancer types.

Circulating miR-221/222 expression as microRNA biomarker predicting tamoxifen treatment outcome: a case-control study

The high mortality rate in breast cancer (BC) patients is generally due to metastases resistant to systemic therapy. Two causes of systemic therapy resistance in BC patients are circulating miRNAs-221 and miR-222, leading to improved BC cell proliferation, survival, and reduced cell apoptosis. This study investigated the miRNA expression changes associated with cancer cell resistance to tamoxifen therapy and is expected to be clinically meaningful before providing endocrine therapy to luminal-type BC patients who express them.

Methods

This case-control research included individuals with the luminal subtype of BC who had received tamoxifen medication for around one year. Furthermore, the case group contained 15 individuals with local recurrence or metastases, while the control group comprised 19 patients without local recurrence or metastases. Plasma miR-221/222 quantification was performed with real-time PCR using transcript-specific primers.

Results

A significant difference was found in circulating miR-221 expression between cases and controls (P=0.005) but not in miR-222 expression (P=0.070). There were no significant differences between miR-221/222 expression, progesterone receptor, Ki67 protein levels, lymphovascular invasion, and stage. However, receiver operator characteristic curve analyses showed miR-221/222 expressions predictive of tamoxifen resistance (P=0.030) with a sensitivity of 60.00 and a specificity of 83.33%.

Conclusion

The use of circulating miR-221/222 expression can predict relapse as well as resistance to tamoxifen treatment in BC patients, and their testing is recommended for luminal subtype BC patients who will undergo tamoxifen therapy to determine their risk of tamoxifen resistance early, increasing treatment effectiveness.

Evaluating steroid hormone receptor interactions using the live-cell NanoBRET proximity assay

Steroid hormone receptors play a crucial role in the development and characterization of the majority of breast cancers. These receptors canonically function through homodimerization, but physical interactions between different hormone receptors play a key role in cell functions as well. The estrogen receptor (ERα) and progesterone receptor (PR), for example, are involved in a complex set of interactions known as ERα/PR crosstalk. Here, we developed a valuable panel of nuclear receptor expression plasmids specifically for use in NanoBRET assays to assess nuclear receptor homo- and heterodimerization. We demonstrate the utility of this assay system by assessing ERα/PR physical interaction in the context of the endocrine therapy resistance-associated ERα Y537S mutation. We identify a role of the ERα Y537S mutation beyond that of constitutive activity of the receptor; it also increases ERα/PR crosstalk. In total, the NanoBRET assay provides a novel avenue for investigating hormone receptor crosstalk. Future research may use this system to assess the effects of other clinically significant hormone receptor mutations on hormone receptor crosstalk.

Dual functionality of pyrimidine and flavone in targeting genomic variants of EGFR and ER receptors to influence the differential survival rates in breast cancer patients

Breast cancer ranks as one of the most prevalent forms of cancer and stands as the primary global cause of mortality among women. Overexpression of EGFR and ER receptors or their genomic alterations leads to malignant transformation, disease aggression and is linked to poor patient survival outcomes. The clinical breast cancer patient's genomic expression, survival analysis, and computational drug-targeting approaches were used to identify best-hit phytochemicals for therapeutic purposes. Breast cancer patients have genomic alterations in EGFR (4%, n = 5699) and ER (9%, n = 8461), with the highest proportion being missense mutations. No statistically significant difference was observed in the patient survival rates between the altered and unaltered ER groups, unlike EGFR, with the lowest survival rates in the altered group. Computational screening of natural compound libraries (7711) against each EGFR (3POZ) and ER (3ERT) receptor shortlists the best-hit 3 compounds with minimum docking score (ΔG = -7.9 to -10.8), MMGBSA (-40.16 to -51.91 kcal/mol), strong intermolecular H-bonding, drug-like properties with least kd, and ki. MD simulation studies display stable RMSD, RMSF, and good residual correlation of best-hit common compounds (PubChem ID: 5281672 and 5280863) targeting both EGFR and ER receptors. In vitro, studies revealed that these common drugs exhibited a high anti-proliferative effect on MCF-7 and MDA-MB-231 breast cancer cells, with effective IC50 values (15-40 μM) and lower free energy, kd, and ki (5281672 > 5280863 > 5330286) much affecting HEK-293 non-cancerous cells, indicating the safety profile. The experimental and computational correlation studies suggest that the highly expressed EGFR and ER receptors in breast cancer patients having poor survival rates can be effectively targeted with best-hit common potent drugs with a multi-target therapeutic approach. Insight Box: The findings of this study provide valuable insights into the genomic/proteomic data, breast cancer patient's survival analysis, and EGFR and ER receptor variants structural analysis. The genetic alterations analysis of EGFR and ER/ESR1 in breast cancer patients reveals the high frequency of mutation types, which affect patient's survival rate and targeted therapies. The common best-hit compounds affect the cell survival patterns with effective IC50, drug-like properties having lower equilibrium and dissociation constants demonstrating the anti-proliferative effects. This work integrates altered receptor structural analysis, molecular interaction-based simulations, and ADMET properties to illuminate the identified best hits phytochemicals potential efficacy targeting both EGFR and ER receptors, demonstrating a multi-target therapeutic approach.

Glucocorticoid induced loss of oestrogen receptor alpha gene methylation and restoration of sensitivity to fulvestrant in triple negative breast cancer

The response to psychological stress can differ depending on the type and duration of the stressor. Acute stress can facilitate a "fight or flight response" and aid survival, whereas chronic long-term stress with the persistent release of stress hormones such as cortisol has been shown to be detrimental to health. We are now beginning to understand how this stress hormone response impacts important processes such as DNA repair and cell proliferation processes in breast cancer. However, it is not known what epigenetic changes stress hormones induce in breast cancer. Epigenetic mechanisms include modification of DNA and histones within chromatin that may be involved in governing the transcriptional processes in cancer cells in response to changes by endogenous stress hormones. The contribution of endogenous acute or long-term exposure of glucocorticoid stress hormones, and exogenous glucocorticoids to methylation patterns in breast cancer tissues with different aetiologies remains to be evaluated. In vitro and in vivo models were developed to investigate the epigenetic modifications and their contribution to breast cancer progression and aetiology. A panel of triple negative breast cancer cell lines were treated with the glucocorticoid, cortisol which resulted in epigenetic alteration characterised by loss of methylation on promoter regions of tumour suppressor genes including ESR1, and loss of methylation on LINE-1 repetitive element used as a surrogate marker for global methylation. This was verified in vivo in MDA-MB-231 xenografts; the model verified the loss of methylation on ESR1 promoter, and subsequent increase in ESR1 expression in primary tumours in mice subjected to restraint stress. Our study highlights that DNA methylation landscape in breast cancer can be altered in response to stress and glucocorticoid treatment.

Curcumol inhibits breast cancer growth via NCL/ERα36 and the PI3K/AKT pathway

Background: Breast cancer (BC) is the most common malignancy worldwide. ERα36 (ERα66 variant) is expressed in many breast cancer cells, especially highly expressed in tamoxifen (TAM)-resistant cell lines and triple-negative breast cancer, and our previous work revealed that nucleolin (NCL) is a protein target of curcumol. This study is aimed at investigating the effect and mechanism of curcumol on ERα36 positive breast cancer cells, and the relationship between curcumol's target protein NCL and ERα36. Study design: Application of in vivo and in vitro studies to reveal the mechanism of curcumol in inhibiting BC growth and the relationship between curcumol's target protein NCL and ERα36. Methods: The anti-tumor effect of curcumol was quantified via an MTT assay, colony formation and cycle arrest, respectively. The expressions of ERα36, NCL and the proteins involved in PI3K/AKT signaling were evaluated by western blotting. The interaction between two proteins was detected using co-immunoprecipitation (Co-IP) and an immunofluorescence assay. A mouse xenograft model was established to verify the role of ERα36 in breast cancer cells and curcumol's effect on ERα36 positive cancer cells. Results: Curcumol inhibited the cell growth, caused cell cycle arrest, decreased cell cycle related proteins and inactivated the PI3K/AKT pathway in ERα36 positive breast cancer cells. There is a positive correlation between NCL and ERα36 in breast cancer cells. In addition, ERα36 bound to NCL; the two proteins were distributed in the nucleus, cytoplasm and plasma membrane, where their expression was obviously decreased by curcumol. Moreover, NCL silenced by NCL siRNA blocked the cell cycle progress and inhibited the activation of PI3K/AKT in MDA-MB-231 cells, while overexpressed ERα36 increased the expression of NCL, promoted the cell cycle progress and enhanced the activity of PI3K/AKT in MCF-7 cells. NCL knockdown or ERα36 overexpression attenuated the effect of curcumol on breast cancer cells. Conclusion: Curcumol reduced the proliferation of breast cancer cells by targeting NCL/ERα36 and inactivating the PI3K/AKT pathway.

Functional Relationships between Long Non-Coding RNAs and Estrogen Receptor Alpha: A New Frontier in Hormone-Responsive Breast Cancer Management

In the complex and articulated machinery of the human genome, less than 2% of the transcriptome encodes for proteins, while at least 75% is actively transcribed into non-coding RNAs (ncRNAs). Among the non-coding transcripts, those ≥200 nucleotides long (lncRNAs) are receiving growing attention for their involvement in human diseases, particularly cancer. Genomic studies have revealed the multiplicity of processes, including neoplastic transformation and tumor progression, in which lncRNAs are involved by regulating gene expression at epigenetic, transcriptional, and post-transcriptional levels by mechanism(s) that still need to be clarified. In breast cancer, several lncRNAs were identified and demonstrated to have either oncogenic or tumor-suppressive roles. The functional understanding of the mechanisms of lncRNA action in this disease could represent a potential for translational applications, as these molecules may serve as novel biomarkers of clinical use and potential therapeutic targets. This review highlights the relationship between lncRNAs and the principal hallmark of the luminal breast cancer phenotype, estrogen receptor α (ERα), providing an overview of new potential ways to inhibit estrogenic signaling via this nuclear receptor toward escaping resistance to endocrine therapy.

Adjuvant radiation therapy for older women with early-stage breast cancer: a propensity-matched SEER analysis

INTRODUCTION

The purpose was to evaluate the effect of adjuvant radiation therapy on the survival prognosis of older women with early-stage breast cancer under different surgical treatments.

METHODS

We collected patients from the Surveillance, Epidemiology and End Results (SEER) database. Elderly female patients (≥ 70 years) with stage I-IIB diagnosed with invasive carcinoma in 1988-2017 were included. After propensity score matching (PSM), the prognosis of patients who underwent breast-conserving surgery or mastectomy was calculated separately. The effects of radiotherapy on the survival of three special population groups (breast-conserving surgery + T1N0M0 + ER positive, mastectomy + T3N0M0 and mastectomy + T1-2N1M0) were analyzed selectively.

RESULTS

Of 106,553 older women with early-stage breast cancer were identified. 48,630 patients had received radiotherapy, while 57,923 patients had not. After PSM, older women undergoing breast-conserving surgery benefited significantly from radiotherapy (both OS and BCSS p < 0.001), for patients with T1N0M0 and ER-positive breast cancer (both OS and BCSS p < 0.001). In the subgroup of T1-2N1M0 breast cancer treated by mastectomy, patients undergoing radiotherapy had a worse survival as well (OS p < 0.001; BCSS p = 0.0907). While in the subgroup of T3N0M0 breast cancer treated by mastectomy, survival analyses showed no statistical differences between patients receiving radiation or not (OS p = 0.1778, BCSS p = 0.6957).

CONCLUSIONS

This study indicated the clinical effects of radiation on older women who received different surgical treatments. Our study suggested that radiotherapy should be omitted in older women undergoing mastectomy + T3N0M0 or T1-2N1M0 and radiotherapy could be considered in women with T1N0M0 + ER-positive undergoing breast-conserving surgery.

FDXR drives primary and endocrine-resistant tumor cell growth in ER+ breast cancer via CPT1A-mediated fatty acid oxidation

Background

The majority of breast cancers (BCs) expressing estrogen receptor (ER) have shown endocrine resistance. Our previous study demonstrated that ferredoxin reductase (FDXR) promoted mitochondrial function and ER+ breast tumorigenesis. But the underlying mechanism is not clear.

Methods

Liquid chromatography (LC) tandem mass spectrometry (MS/MS)-based metabolite profiling was utilized to reveal the metabolites regulated by FDXR. RNA microarray was utilized to determine the potential downstream targets of FDXR. Seahorse XF24 analyzer was performed to analyze the FAO-mediated oxygen consumption rate (OCR). Q-PCR and western blotting assays were used to measure expression levels of FDXR and CPT1A. MTS, 2D colony formation and anchorage-independent growth assays were used to evaluate the effects of FDXR or drug treatments on tumor cell growth of primary or endocrine-resistant breast cancer cells.

Results

We found that depletion of FDXR inhibited fatty acid oxidation (FAO) by suppressing CPT1A expression. Endocrine treatment increased the expression levels of both FDXR and CPT1A. Further, we showed that depletion of FDXR or FAO inhibitor etomoxir treatment reduced primary and endocrine-resistant breast cancer cell growth. Therapeutically, combining endocrine therapy with FAO inhibitor etomoxir synergistically inhibits primary and endocrine-resistant breast cancer cell growth.

Discussion

We reveal that the FDXR-CPT1A-FAO signaling axis is essential for primary and endocrine-resistant breast cancer cell growth, thus providing a potential combinatory therapy against endocrine resistance in ER+ breast cancer.

Predicting the Response of Neoadjuvant Chemotherapy in Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer With Axillary Lymph Node Metastasis by Multigene Assay

PURPOSE

The GenesWell™ breast cancer test (BCT) is a recently developed multigene assay that predicts the risk of distant recurrence in patients with hormone receptor-positive (HR+) and human epidermal growth factor-2 negative (HER2-) early breast cancer (BC). The ability of this assay to predict the response to neoadjuvant chemotherapy (NACT) has not been established to date.

METHODS

Biopsy specimens from HR+/HER2- BC patients with axillary lymph node (LN) metastasis who underwent NACT were analyzed using the BCT score. The modified BCT score was developed and patients classified into high-and low-response groups. A total of 88 patients were available for the BCT score among the 108 eligible patients. The median follow-up duration was 35.9 (7.8-128.5) months.

RESULTS

Among them, 61 (65.1%) had cN1 and 53 (60.2%) had cT1 or cT2 disease. The BCT score was low in 25 (28.4%) patients and high in 63 (71.6%). Among the 50 patients with pathologic complete response or partial response, 41 (82.0%) were in the high BCT score group and 9 (18.0%) were in the low BCT score group. Among the 38 patients with stable or progressive disease, 22 (57.9%) were in the high BCT score group and 16 (42.1%) were in the low BCT score group (p = 0.025). Ki-67 before NACT was a significant factor for predicting tumor response (p = 0.006; 3.81 [1.50-10.16]). The BCT score showed a significant response to NACT (p = 0.016; 4.18 [1.34-14.28]). Distant metastasis-free survival was significantly different between the high- and low-response groups (p = 0.004).

CONCLUSION

We demonstrated that the BCT score predicts NACT responsiveness in HR+/HER2- BC with LN metastasis and might help determine whether NACT should be performed. Further studies are required to validate these results.

ECM1 is associated with endocrine resistance in ER+ breast cancers

Extracellular matrix protein 1 (ECM1) is associated with a poor prognosis of breast cancers. However, the role of ECM1 with endocrine resistance in estrogen receptor-positive (ER⁺) breast cancers has not been elucidated yet. We show that ECM1 promotes endocrine resistance in ER⁺ breast cancers. ECM1 is overexpressed in luminal breast cancer patients compared to the basal type of breast cancer. Significantly, higher expression of ECM1 is associated with poor response to endocrine therapies in luminal B breast cancer patients. We found that ECM1 is upregulated in CAMA1 and MDA-MB-361 cells grown in long-term estrogen-deprived (LTED) conditions. Moreover, the ablation of ECM1 significantly inhibited the proliferation of CAMA1 LTED and MDA-MB-361 LTED cells. Finally, an interrogation of a dataset containing transcriptome and proteome of breast cancer cell lines revealed that the level of ECM1 mRNA is positively correlated with that of phosphorylated Src. Based on these findings, we strongly suggest that ECM1 significantly contributes to the acquisition of endocrine resistance in ER⁺ breast cancers by the activation of Src.

Beyond the snapshot: optimizing prognostication and prediction by moving from fixed to functional multidimensional cancer pathology

The role of pathology in patient management has evolved over time from the retrospective review of cells, tissue, and disease (‘what happened’) to a prospective outlook (‘what will happen’). Examination of a static, two‐dimensional hematoxylin and eosin (H&E)‐stained tissue slide has traditionally been the pathologist's primary task, but novel ancillary techniques enabled by technological breakthroughs have supported pathologists in their increasing ability to predict disease status and behaviour. Nevertheless, the informational limits of 2D, fixed tissue are now being reached and technological innovation is urgently needed to ensure that our understanding of disease entities continues to support improved individualized treatment options. Here we review pioneering work currently underway in the field of cancer pathology that has the potential to capture information beyond the current basic snapshot. A selection of exciting new technologies is discussed that promise to facilitate integration of the functional and multidimensional (space and time) information needed to optimize the prognostic and predictive value of cancer pathology. Learning how to analyse, interpret, and apply the wealth of data acquired by these new approaches will challenge the knowledge and skills of the pathology community. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

The Role of Progesterone Receptors in Breast Cancer

The progesterone receptor (PR) modulates estrogen receptors α (ERα) action in breast cancer; it is an upregulated target gene of ER, and its expression is dependent on estrogen. PR is also a valuable prognostic biomarker in breast cancer, especially in hormone-positive breast cancer. High expression of PR is more frequently observed in tumors with a better baseline prognosis (ie, luminal A) than tumors with a poor baseline prognosis (ie, luminal B). In the following review, we present the role of PR in breast cancer, including the genomic characteristics and pathways in breast cancer, PR and endocrine therapy.

Resistance to endocrine therapy in HR + and/or HER2 + breast cancer: the most promising predictive biomarkers

Breast cancer is the most common cancer in women. It is a heterogeneous disease, encompassing different biological subtypes that differ in histological features, outcomes, clinical behaviour and different molecular subtypes. Therapy has progressed substantially over the past years with a reduction both for locoregional and systemic therapy. Endocrine therapies have considerably reduced cancer recurrence and mortality. Despite the major diagnostic and therapeutic innovations, resistance to therapy has become a main challenge, especially in metastatic breast cancer, and became a major factor limiting the use of endocrine therapeutic agents in ER positive breast cancers. Approximately 50% of patients with ER positive metastatic disease achieve a complete or partial response with endocrine therapy. However, in the remaining patients, the benefit is limited due to resistance, intrinsic or acquired, resulting in disease progression and poor outcome.Tumour heterogeneity as well as acquired genetic changes and therapeutics pressure have been involved in the endocrine therapy resistance. Nowadays, targeted sequencing of genes involved in cancer has provided insights about genomic tumour evolution throughout treatment and resistance driver mutations. Several studies have described multiple alterations in receptor tyrosine kinases, signalling pathways such as Phosphoinositide-3-kinase-protein kinase B/Akt/mTOR (PI3K/Akt/mTOR) and Mitogen-activated protein kinase (MAPK), cell cycle machinery and their implications in endocrine treatment failure.One of the current concern in cancer is personalized therapy. The focus has been the discovery of new potentially predictive biomarkers capable to identify reliably the most appropriate therapy regimen and which patients will experience disease relapse. The major concern is also to avoid overtreatment/undertreatment and development of resistance.This review focuses on the most promising predictive biomarkers of resistance in estrogen receptor-positive breast cancer and the emerging role of circulating free-DNA as a powerful tool for longitudinal monitoring of tumour molecular profile throughout treatment.

Dynamics of Serum Thymidine Kinase 1 at the First Cycle of Neoadjuvant Chemotherapy Predicts Outcome of Disease in Estrogen-Receptor-Positive Breast Cancer

Simple Summary

Chemotherapy before surgery (NAC) is an option for high-risk breast cancer (BC) patients. Pathologic complete response (pCR) predicts long-term outcome and has become a surrogate biomarker for survival. pCR is, however, reached in only <10% of hormone-receptor-positive (ER+) patients and is of limited prognostic value. Biomarkers able to predict outcome early during NAC would facilitate individualized therapy with the possibility to adjust or interrupt an ineffective therapy. Here, it is shown that differential response of the serum concentration of thymidine kinase 1, an enzyme involved in the DNA synthesis and released from the tumor into the blood, 48 h after the first cycle of NAC, predicts long-term outcome in localized advanced ER+/HER2-BC. The different reactions to chemotherapy could be used to guide this process early during NAC and utilized to identify mechanisms of tumor sensitivity that could provide a prediction of long-term outcome prior to chemotherapy.

Abstract

Pathologic complete response (pCR) predicts the long-term outcome of neoadjuvantly treated (NAC) breast cancer (BC) but is reached in <10% of hormone-receptor-positive patients. Biomarkers enabling adjustment or interruption of an ineffective therapy are desired. Here, we evaluated whether changes in the serum concentration of thymidine kinase 1 (sTK1) during NAC could be utilized as a biomarker. In the PROMIX trial, women with localized HER2- BC received neoadjuvant epirubicin/docetaxel in six cycles. sTK1 was measured with an ELISA in 54 patients at cycles 1–4 and in an additional 77 patients before and 48 h after treatment 1. Treatment resulted in a 2-fold increase of sTK1 before and a 3-fold increase 48 h after the cycles, except for the first cycle, where half of the patients reacted with a significant decrease and the other half with an increase of sTK1. In Kaplan–Meier estimates of ER+ patients divided by the median of the post/pre-treatment sTK1 ratio at the first treatment cycle, OS was 97.7% and 78% (p = 0.005), and DFS was 90.7% and 68% (p = 0.006), respectively. Thus, the response of sTK1 at the first cycle of chemotherapy could be used both as an early biomarker for the guidance of chemotherapy and for the study of inherent tumor chemo-sensitivity, which could predict long-term outcome prior to therapy.

Prognostic value of breast MRI characteristics before and during neoadjuvant endocrine therapy in patients with ER+/HER2- breast cancer

Objective:

To investigate whether BIRADS MRI characteristics before or during neoadjuvant endocrine therapy (NET) are associated with the preoperative endocrine prognostic index (PEPI) in ER+/HER2- breast cancer patients.

Methods:

This retrospective observational cohort study included 35 ER+/HER2- patients with 38 tumors (3 bilateral cases) treated with NET. The pre- and midtreatment (after 3 months) MRIs were evaluated by two breast radiologists for BIRADS imaging characteristics, shrinkage pattern, and radiologic response. PEPI was used as end point. PEPI is based on the post-treatment surgical specimen’s pT- and pN-stage, Ki67, and ER-status. Tumors were assigned PEPI-1 (good prognosis) or PEPI-2/3 (poor prognosis). We investigated whether pre- and midtreatment BIRADS characteristics were associated with PEPI.

Results:

Median patient age was 65 years (interquartile interval [IQI]: 53, 70). 17 tumors (44.7%) were associated with good prognosis (PEPI-1), and 21 tumors (55.3%) with poor prognosis (PEPI-2/3). A larger reduction in tumor size after 3 months of NET was significantly associated with PEPI; 10 mm (IQI: 5, 13.5) in PEPI-1 tumors vs 4.5 mm (IQI: 3, 7; p = .045) in PEPI-2/3 tumors. Other BIRADS characteristics, shrinkage pattern or radiologic response were not associated with PEPI.

Conclusion:

Only a larger reduction in tumor size on MRI after 3 months of NET was associated with PEPI-1 (good prognosis) in ER+/HER2- breast cancer patients.

Advances in knowledge:

MRI characteristics previously reported to be associated with prognosis during neoadjuvant chemotherapy are not necessarily associated with prognosis during NET in ER+/HER2- breast cancer patients.

A Novel Dual Antibody Staining Assay to Measure Estrogen Receptor Transcriptional Activity

Activity of the canonical estrogen receptor (ER) pathway is equivalent to functional activity of the nuclear ER transcription factor. Monoclonal antibodies (MoAbs) that identify nuclear ER in cells and tissue samples are frequently used to assess ER transcriptional activity, however, it remains unclear if this approach is sufficiently predictive of ER pathway activity. This study uses ER-positive breast cancer cell lines (MCF7 and T47D) in which ER transcriptional activity was quantified using an mRNA-based ER pathway activity assay. The relationship between ER activity and nuclear ER staining with ER MoAbs was then investigated. Confirming earlier findings, the results show that while the presence of ER in the cell nucleus is a prerequisite for ER activity, it is not predictive of ER transcriptional activity. There were remarkable differences in the behaviours of the antibodies used in the study. EP1 and 1D5 showed reduced nuclear staining when ER was transcriptionally active, while staining with H4624 was independent of ER activity. To improve discrimination between active and inactive nuclear ER based on ER staining, a method was developed which consists of dual ER MoAb immunofluorescent staining, followed by generation of a digital image with a standard digital pathology scanner. Then a cell nucleus detection algorithm and per cell calculation of the nuclear H4624/EP1 fluorescence intensity ratio was applied, where a high H4624/EP1 ratio predicts an active ER pathway. With this method, the EP1 and 1D5 antibodies are interchangeable. We hypothesize that the transcriptional activation of ER hides the epitope recognized by MoAbs EP1 and 1D5, while H4624 binds an ER epitope that remains accessible during ER pathway activation. The method described in this study should add substantial value to the assessment of ER pathway activity for biomedical research and diagnostics.

Metabotropic glutamate receptor 1 is associated with unfavorable prognosis in ER-negative and triple-negative breast cancer

New therapies are an urgent medical need in all breast cancer subgroups. Metabotropic glutamate receptor 1 (mGluR1) is suggested as a potential new molecular target. We examined the prevalence mGluR1 expression in different clinically relevant breast cancer subgroups and determined its association with prognosis. In this retrospective cohort, 394 consecutive primary breast cancer tissues were incorporated into a tissue microarray and immunohistochemically stained for mGluR1. The prevalence of mGluR1 protein expression in different breast cancer subgroups was evaluated and correlated with metastasis-free survival (MFS) and overall survival (OS). In total, 56% (n = 219) breast cancer tissues had mGluR1 expression. In estrogen receptor (ER)-negative tumors, 31% (n = 18/58) had mGluR1 expression that was significantly associated with MFS (HR 5.00, 95% CI 1.03–24.35, p = 0.046) in multivariate analysis, independently from other prognostic factors. Of the 44 triple-negative breast cancer (TNBC), 25% (n = 11) expressed mGluR1. mGluR1 expression in TNBC was significantly associated with shorter MFS (HR 8.60, 95% CI 1.06–20.39, p = 0.044) and with poor OS (HR 16.07, 95% CI 1.16–223.10, p = 0.039). In conclusion, mGluR1 is frequently expressed in breast cancer. In ER-negative breast cancer and in TNBC mGluR1 protein expression is an unfavorable prognostic marker. This study provides rationale to explore mGluR1 as a novel target for breast cancer treatment, especially for the more aggressive TNBC.

Patterns of biomarker expression in patients treated with primary endocrine therapy - a unique insight using core needle biopsy tissue microarray

Purpose

Prediction of response to primary endocrine therapy (PET) in older women is based on measurement of oestrogen receptor (ER), progesterone receptor (PgR) and human epidermal growth factor (HER)-2. This study uses a unique method for construction of core needle biopsy (CNB) tissue microarray (TMA), to correlate expression of a panel of 17 biomarkers with clinical outcome, in patients receiving PET.

Methods

Over 37 years (1973–2010), 1758 older (≥ 70 years) women with operable primary breast cancer were managed in a single institution. Of these, 693 had sufficient good-quality CNB to construct TMA, of which 334 had ER-positive tumours treated by PET with a minimum of 6-month follow-up. A panel of biomarkers was measured by immunohistochemistry (ER, PgR, HER2, Ki-67, p53, CK5/6, CK 7/8, EGFR, BCL-2, MUC1, VEGF, LKB1, BRCA1, HER3, HER4, PTEN and AIB1). Expression of each biomarker was dichotomised into ‘low’ or ‘high’ based on breast cancer-specific survival (BCSS).

Results

From the panel of biomarkers, multivariate analysis showed:

High ER (p = 0.003) and PgR (p = 0.002) were associated with clinical benefit of PET at 6 months, as opposed to progressive disease.

High ER (p = 0.0023), PgR (p < 0.001) and BCL-2 (p = 0.043) and low LKB1 (p = 0.022) were associated with longer time to progression.

High PgR (p < 0.001) and low MUC1 (p = 0.021) were associated with better BCSS.

Expression of other biomarkers did not show any significant correlation.

Conclusions

In addition to ER and PgR; MUC1, BCL-2 and LKB1 are important in determining the outcome of PET in this cohort.

Electronic supplementary material

The online version of this article (10.1007/s10549-020-06023-4) contains supplementary material, which is available to authorised users.

Machine Learning-Based Radiomics Nomogram Using Magnetic Resonance Images for Prediction of Neoadjuvant Chemotherapy Efficacy in Breast Cancer Patients

Purpose: The construction and validation of a radiomics nomogram based on machine learning using magnetic resonance image (MRI) for predicting the efficacy of neoadjuvant chemotherapy (NACT) in patients with breast cancer (BCa).

Methods: This retrospective investigation consisted of 158 patients who were diagnosed with BCa and underwent MRI before NACT, of which 33 patients experienced pathological complete response (pCR) by the postoperative pathological examination. The patients with BCa were divided into the training set (n = 110) and test set (n = 48) randomly. The features were selected by the maximum relevance minimum redundancy (mRMR) and absolute shrinkage and selection operator (LASSO) algorithm in the training set. In return, the radiomics signature was established using machine learning. The predictive score of each patient was calculated using the radiomics signature formula. Finally, the predictive scores and clinical factors were used to perform the multivariate logistic regression and construct the nomogram. Receiver operating characteristics (ROC) analyses were used to assess and validate the diagnostic accuracy of the nomogram in the test set. Lastly, the usefulness of the nomogram was confirmed via decision curve analysis (DCA).

Results: The radiomics signature was well-discriminated in the training set [AUC 0.835, specificity 71.32%, and sensitivity 82.61%], and test set (AUC 0.834, specificity 73.21%, and sensitivity 80%). Containing the radiomics signature and hormone status, the radiomics nomogram showed good calibration and discrimination in the training set [AUC 0.888, specificity 79.31%, and sensitivity 86.96%] and test set (AUC 0.879, specificity 82.19%, and sensitivity 83.57%). The decision curve indicated the clinical usefulness of our nomogram.

Conclusion: Our radiomics nomogram showed good discrimination in patients with BCa who experience pCR after NACT. The model may aid physicians in predicting how specific patients may respond to BCa treatments in the future.

Contralateral parenchymal enhancement on breast MRI before and during neoadjuvant endocrine therapy in relation to the preoperative endocrine prognostic index

Objectives

To investigate whether contralateral parenchymal enhancement (CPE) on MRI during neoadjuvant endocrine therapy (NET) is associated with the preoperative endocrine prognostic index (PEPI) of ER+/HER2− breast cancer.

Methods

This retrospective observational cohort study included 40 unilateral ER+/HER2− breast cancer patients treated with NET. Patients received NET for 6 to 9 months with MRI response monitoring after 3 and/or 6 months. PEPI was used as endpoint. PEPI is based on surgery-derived pathology (pT- and pN-stage, Ki67, and ER-status) and stratifies patients in three groups with distinct prognoses. Mixed effects and ROC analysis were performed to investigate whether CPE was associated with PEPI and to assess discriminatory ability.

Results

The median patient age was 61 (interquartile interval: 52, 69). Twelve patients had PEPI-1 (good prognosis), 15 PEPI-2 (intermediate), and 13 PEPI-3 (poor). High pretreatment CPE was associated with PEPI-3: pretreatment CPE was 39.4% higher on average (95% CI = 1.3, 91.9%; p = .047) compared with PEPI-1. CPE decreased after 3 months in PEPI-2 and PEPI-3. The average reduction was 24.4% (95% CI = 2.6, 41.3%; p = .032) in PEPI-2 and 29.2% (95% CI = 7.8, 45.6%; p = .011) in PEPI-3 compared with baseline. Change in CPE was predictive of PEPI-1 vs PEPI-2+3 (AUC = 0.77; 95% CI = 0.57, 0.96).

Conclusions

CPE during NET is associated with PEPI-group in ER+/HER2− breast cancer: a high pretreatment CPE and a decrease in CPE during NET were associated with a poor prognosis after NET on the basis of PEPI.

Key Points

• Change in contralateral breast parenchymal enhancement on MRI during neoadjuvant endocrine therapy distinguished between patients with a good and intermediate/poor prognosis at final pathology.

• Patients with a poor prognosis at final pathology showed higher baseline parenchymal enhancement on average compared to patients with a good prognosis.

• Patients with an intermediate/poor prognosis at final pathology showed a higher average reduction in parenchymal enhancement after 3 months of neoadjuvant endocrine therapy.

Electronic supplementary material

The online version of this article (10.1007/s00330-020-07058-3) contains supplementary material, which is available to authorized users.

Global View of Candidate Therapeutic Target Genes in Hormone-Responsive Breast Cancer

Breast cancer (BC) is a heterogeneous disease characterized by different biopathological features, differential response to therapy and substantial variability in long-term-survival. BC heterogeneity recapitulates genetic and epigenetic alterations affecting transformed cell behavior. The estrogen receptor alpha positive (ERα+) is the most common BC subtype, generally associated with a better prognosis and improved long-term survival, when compared to ERα-tumors. This is mainly due to the efficacy of endocrine therapy, that interfering with estrogen biosynthesis and actions blocks ER-mediated cell proliferation and tumor spread. Acquired resistance to endocrine therapy, however, represents a great challenge in the clinical management of ERα+ BC, causing tumor growth and recurrence irrespective of estrogen blockade. Improving overall survival in such cases requires new and effective anticancer drugs, allowing adjuvant treatments able to overcome resistance to first-line endocrine therapy. To date, several studies focus on the application of loss-of-function genome-wide screenings to identify key (hub) “fitness” genes essential for BC progression and representing candidate drug targets to overcome lack of response, or acquired resistance, to current therapies. Here, we review the biological significance of essential genes and relative functional pathways affected in ERα+ BC, most of which are strictly interconnected with each other and represent potential effective targets for novel molecular therapies.

Circulating tumour cell enumeration does not correlate with Miller-Payne grade in a cohort of breast cancer patients undergoing neoadjuvant chemotherapy

Purpose

The association between pathological complete response (pCR) in patients receiving neoadjuvant chemotherapy (NAC) for breast cancer and Circulating Tumour Cells (CTCs) is not clear. The aim of this study was to assess whether CTC enumeration could be used to predict pathological response to NAC in breast cancer as measured by the Miller–Payne grading system.

Methods

Twenty-six patients were recruited, and blood samples were taken pre- and post-NAC. CTCs were isolated using the ScreenCell device and stained using a modified Giemsa stain. CTCs were enumerated by 2 pathologists and classified as single CTCs, doublets, clusters/microemboli and correlated with the pathological response as measured by the Miller–Payne grading system. χ² or ANOVA was performed in SPSS 24.0 statistics software for associations.

Results

89% of patients had invasive ductal carcinoma (IDC) and 11% invasive lobular carcinoma (ILC). At baseline 85% of patients had CTCs present, median 7 (0–161) CTCs per 3 ml of whole blood. Post-chemotherapy, 58% had an increase in CTCs. This did not correlate with the Miller–Payne grade of response. No significant association was identified between the number of CTCs and clinical characteristics; however, we did observe a correlation between pre-treatment CTC counts and body mass index, p < 0.05.

Conclusions

Patients with a complete response to NAC still had CTCs present, suggesting enumeration is not sufficient to aid surgery stratification. Additional characterisation and larger studies are needed to further characterise CTCs isolated pre- and post-chemotherapy. Long-term follow-up of these patients will determine the significance of CTCs in NAC breast cancer patients.

Electronic supplementary material

The online version of this article (10.1007/s10549-020-05658-7) contains supplementary material, which is available to authorized users.

Neoadjuvant endocrine therapy for luminal breast cancer treatment: a first-choice alternative in times of crisis such as the COVID-19 pandemic

The epidemiological emergency caused by CoV-2 (COVID-19) has changed priorities in breast cancer management. In those places where the pandemic has had the greatest effect, it is of paramount importance for most patients to be at home, reducing or postponing their attendance at clinics, as well as avoiding surgeries. In this scenario, neoadjuvant endocrine treatment could be an appropriate alternative treatment for hormone receptor positive breast cancer (luminal-like tumours) in order to minimise hospital admissions and to delay elective surgeries. Accordingly, we present a simple protocol that can be applied to most cases of luminal-like breast cancer and is appropriate for the majority of secondary or tertiary medical centres, or even primary care.

Nanomedicine: A Promising Avenue for the Development of Effective Therapy for Breast Cancer

PURPOSE

Breast cancer is the most probable cancer among women. However, the available treatment is based on targeting different stages of breast cancer viz., radiation therapy, hormonal therapy, chemotherapy, and surgical interventions, which have some limitations. The available chemotherapeutics are associated with problems like low solubility, low permeability, high first-pass metabolism, and P-glycoprotein efflux. Hence, the aforementioned restrictions lead to ineffective treatment. Multiple chemotherapeutics can also cause resistance in tumors. So, the purpose is to develop an effective therapeutic regimen for the treatment of breast cancer by applying a nanomedicinal approach.

METHODS

This review has been conducted on a systematic search strategy, based on relevant literature available on Pub Med, MedlinePlus, Google Scholar, and Sciencedirect up to November 2019 using keywords present in abstract and title of the review. As per our inclusion and exclusion criteria, 226 articles were screened. Among 226, a total of 40 articles were selected for this review.

RESULTS

The significant findings with the currently available treatment is that the drug, besides its distribution to the target-specific site, also distributes to healthy cells, which results in severe side effects. Moreover, the drug is less bioavailable at the site of action; therefore, to overcome this, a high dose is required, which again causes side effects and lower the benefits. Nanomedicinal approaches give an alternative approach to avoid the associated problems of available chemotherapeutics treatment of breast cancer.

CONCLUSION

The nanomedicinal strategies are useful over the conventional treatment of breast cancer and deliver a target-specific drug-using different novel drug delivery approaches.

New Approaches in Breast Cancer Therapy Through Green Nanotechnology and Nano-Ayurvedic Medicine - Pre-Clinical and Pilot Human Clinical Investigations

PURPOSE

The overarching objective of this investigation was to investigate the intervention of green nanotechnology to transform the ancient holistic Ayurvedic medicine scientifically credible through reproducible formulations and rigorous pre-clinical/clinical evaluations.

METHODS

We provide, herein, full details: (i) on the discovery and full characterization of gold nanoparticles-based Nano Swarna Bhasma (henceforth referred to as NSB drug); (ii) In vitro anti-tumor properties of NSB drug in breast tumor cells; (iii) pre-clinical therapeutic efficacy studies of NSB drug in breast tumor bearing SCID mice through oral delivery protocols and (iv) first results of clinical translation, from mice to human breast cancer patients, through pilot human clinical trials, conducted according to the Ayurveda, Yoga and Naturopathy, Unani, Siddha and Homoeopathy (abbreviated as AYUSH) regulatory guidelines of the Government of India in metastatic breast cancer patients.

RESULTS

The preclinical in vitro and in vivo investigations, in breast tumor bearing mice, established unequivocally that the NSB Nano-Ayurvedic medicine-gold nanoparticles-based drug is highly effective in controlling the growth of breast tumors in a dose dependent fashion in vivo. These encouraging pre-clinical results prompted us to seek permission from the Indian Government's holistic medicine approval authority, AYUSH, for conducting clinical trials in human patients. Patients treated with the NSB drug capsules along with the "standard of care treatment" (Arm B) exhibited 100% clinical benefits when compared to patients in the treatment Arm A, thus indicating the tremendous clinical benefits of NSB drug in adjuvant therapy.

CONCLUSION

We have succeeded in clinically translating, from mice to humans, in using proprietary combinations of gold nanoparticles and phytochemicals to develop the Nano-Ayurvedic drug: Nano Swarna Bhasma (NSB), through innovative green nanotechnology, for treating human metastatic breast cancer patients.

Estrogen Receptor Pathway Activity Score to Predict Clinical Response or Resistance to Neoadjuvant Endocrine Therapy in Primary Breast Cancer

Endocrine therapy is important for management of patients with estrogen receptor (ER)-positive breast cancer; however, positive ER staining does not reliably predict therapy response. We assessed the potential to improve prediction of response to endocrine treatment of a novel test that quantifies functional ER pathway activity from mRNA levels of ER pathway-specific target genes. ER pathway activity was assessed on datasets from three neoadjuvant-treated ER-positive breast cancer patient cohorts: Edinburgh: 3-month letrozole, 55 pre-/2-week/posttreatment matched samples; TEAM IIa: 3- to 6-month exemestane, 49 pre-/28 posttreatment paired samples; and NEWEST: 16-week fulvestrant, 39 pretreatment samples. ER target gene mRNA levels were measured in fresh-frozen tissue (Edinburgh, NEWEST) with Affymetrix microarrays, and in formalin-fixed paraffin-embedded samples (TEAM IIa) with qRT-PCR. Approximately one third of ER-positive patients had a functionally inactive ER pathway activity score (ERPAS), which was associated with a nonresponding status. Quantitative ERPAS decreased significantly upon therapy (P < 0.001 Edinburgh and TEAM IIa). Responders had a higher pretreatment ERPAS and a larger 2-week decrease in activity (P = 0.02 Edinburgh). Progressive disease was associated with low baseline ERPAS (P = 0.03 TEAM IIa; P = 0.02 NEWEST), which did not decrease further during treatment (P = 0.003 TEAM IIa). In contrast, the staining-based ER Allred score was not significantly associated with therapy response (P = 0.2). The ERPAS identified a subgroup of ER-positive patients with a functionally inactive ER pathway associated with primary endocrine resistance. Results confirm the potential of measuring functional ER pathway activity to improve prediction of response and resistance to endocrine therapy.

Are contralateral parenchymal enhancement on dynamic contrast-enhanced MRI and genomic ER-pathway activity in ER-positive/HER2-negative breast cancer related?

PURPOSE

To retrospectively explore the relation between parenchymal enhancement of the healthy contralateral breast on dynamic contrast-enhanced magnetic resonance imaging (MRI) and genomic tests for estrogen receptor (ER)-pathway activity in patients with ER-positive/HER2-negative cancer.

METHODS

A subset of 227 consecutively included patients with unilateral invasive ER-positive/HER2-negative breast cancer underwent dynamic contrast-enhanced MRI prior to breast-conserving therapy between 2000 and 2008. Perfusion of the parenchyma in the healthy breast was assessed using a previously reported measure of contralateral parenchymal enhancement (CPE), consisting of the mean of the top-10% late enhancement. ER-pathway activity was assessed from the surgical resection specimen by the previously reported sensitivity to endocrine therapy (SET)-index and ER-factor. The SET-index is a genetic test to estimate survival benefit from endocrine therapy, consisting of genes related to the ESR1 gene. The ER-factor examines other factors as well including protein expression. The relation between CPE and ER-pathway activity was modeled using linear regression.

RESULTS

Patients had a median age of 59 years. CPE was not significantly associated with the SET-index (R-squared = 0.005) nor the ER-factor (R-squared = 0.0002). The only variable significantly different between low and high CPE was age at diagnosis (P < 0.001).

CONCLUSIONS

Contralateral parenchymal enhancement on dynamic contrast-enhanced MRI was not associated with tumor-derived estrogen receptor pathway activity.

Liquid biopsy in breast cancer: A comprehensive review

Breast cancer is the most common cancer among women worldwide. Due to its complexity in nature, effective breast cancer treatment can encounter many challenges. Traditional methods of cancer detection such as tissue biopsy are not comprehensive enough to capture the entire genomic landscape of breast tumors. However, with the introduction of novel techniques, the application of liquid biopsy has been enhanced, enabling the improvement of various aspects of breast cancer management including early diagnosis and screening, prediction of prognosis, early detection of relapse, serial sampling and efficient longitudinal monitoring of disease progress and response to treatment. Various components of tumor cells released into the blood circulation can be analyzed in liquid biopsy sampling, some of which include circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), cell-free RNA, tumor-educated platelets and exosomes. These components can be utilized for different purposes. As an example, ctDNA can be sequenced for genetic profiling of the tumors to enhance individualized treatment and longitudinal screening. CTC plasma count analysis or ctDNA detection after curative tumor resection surgery could facilitate early detection of minimal residual disease, aiding in the initiation of adjuvant therapy to prevent recurrence. Furthermore, CTC plasma count can be assessed to determine the stage and prognosis of breast cancer. In this review, we discuss the advantages and limitations of the various components of liquid biopsy used in breast cancer diagnosis and will expand on aspects that require further focus in future research.

Neoadjuvant Therapy for Breast Cancer as a Model for Translational Research

Neoadjuvant therapy, where patients receive systemic therapy before surgical removal of the tumour, can downstage tumours allowing breast-conserving surgery, rather than mastectomy. In addition to its impact on surgery, the neoadjuvant setting offers a valuable opportunity to monitor individual tumour response. The effectiveness of standard and/or potential new therapies can be tested in the neoadjuvant pre-surgical setting. It can potentially help to identify markers differentiating patients that will potentially benefit from continuing with the same or a different adjuvant treatment enabling personalised treatment. Characterising the molecular response to treatment over time can more accurately identify the significant differences between baseline samples that would not be identified without post-treatment samples. In this review, we discuss the potential and challenges of using the neoadjuvant setting in translational breast cancer research, considering the implications for improving our understanding of response to treatment, predicting therapy benefit, modelling breast cancer dormancy, and the development of drug resistance.

Fulvestrant-Based Combination Therapy for Second-Line Treatment of Hormone Receptor-Positive Advanced Breast Cancer

Fulvestrant is recommended for patients with hormone receptor-positive (HR+) advanced breast cancer (ABC) who progress after aromatase inhibitor therapy. As most patients in this setting have already developed mechanisms of resistance to endocrine therapy, targeting biological pathways associated with endocrine resistance in combination with fulvestrant may improve outcomes. Therefore, evidence supporting a combinatorial treatment approach in the second-line setting was investigated based on a search of PubMed and ClinicalTrials.gov . Twenty-eight studies of targeted therapies plus fulvestrant as second-line treatment for HR+ ABC were identified, including three and six key randomized trials exploring cyclin-dependent kinase 4/6 (CDK4/6) inhibitors and phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) inhibitors plus fulvestrant respectively. Additional combinations with fulvestrant included inhibitors of epidermal growth factor receptors, androgen receptor, and the bromodomain and extra-terminal family of proteins. Across the studies reviewed with available data, the addition of targeted therapies to fulvestrant resulted in clinically meaningful improvements in progression-free survival compared with fulvestrant alone. While some challenging toxicities were observed, most adverse events could be effectively managed. Selection of second-line targeted therapy for use with fulvestrant should consider prior treatment as well as the mutation status of the tumor. In conclusion, available data indicate that fulvestrant combined with agents targeting mechanisms of endocrine resistance is a promising approach. The ongoing trials identified in this review will help further inform the selection of combination treatments with fulvestrant for HR+ ABC.

Potential of Liquid Biopsies for Breast Cancer Screening, Diagnosis, and Response to Treatment

Cancer therapy decisions are often made according to the histopathological-molecular profile of tumor tissue obtained from surgery or biopsy. It has been shown that tumor profiles change with time and treatment, and that tumor tissue is heterogeneous. Thus, other approaches that are easily accessible and less invasive than surgery or biopsy to monitor responses to treatment and predict relapses are urgently needed. In the last few years, the term "liquid biopsies" has been introduced to represent multifunctional circulating biomarkers in the peripheral blood and other physiological fluids of patients with cancer. Liquid biopsies are a noninvasive alternative to tissue biopsies, but they have not been implemented in routine clinical practice for breast cancer. In addition, liquid biopsies seem to be a promising approach for personalized medicine, which enables the prediction, monitoring, and rational selection of appropriate therapy for individual patients. In this review, we outline recent progress and current challenges with liquid biopsies in clinical practice for breast cancer diagnosis, treatment choices, and responses to therapy from a clinician's perspective.

Rg3 inhibits gemcitabine-induced lung cancer cell invasiveness through ROS-dependent, NF-κB- and HIF-1α-mediated downregulation of PTX3

PTX3, a member of the long pentraxin subfamily, associated with innate immunity is indispensable for resistance to some cancer. Gemcitabine, an analog of cytosine arabinoside, has shown restrained benefits because of profound chemoresistance. The PTX3 expression on GEM in human lung cancer cells have not yet been clarified; the present study aimed to show reactive oxygen species (ROS) mediatory PTX3 expression through distinct mechanisms. Whereas ginsenoside Rg3 is a herbal medicine with strong antitumor activity. Furthermore, we tested the hypothesis; Rg3 abrogates GEM-induced production of ROS-mediated activation of Akt and extracellular signal-regulated kinase (ERK) pathways and inhibits nuclear piling-up of nuclear factor kappa B (NF-κB) and HIF-1α. On the basis of time and dose-dependent manner, our data demonstrated that GEM-induced PTX3 expression was dependent on ROS generation as it was abrogated by pretreatment of lung cancer cells with the free radical scavenger N-acetyl-l-cysteine. Our data demonstrated that PTX3 upregulation by GEM correlated with the time-dependent escalation of NF-κB and HIF-1α in the nucleus resulted from phosphorylation-induced degradation of IκBα, whereas HIF-1α upregulation was NF-κB-dependent. Increase in ROS expression in lung cancer cells on GEM treatment preceded the nuclear accumulation of NF-κB and HIF-1α and suppression of ROS diminished these effects. ERK1/2 and Akt activation mediated the effect of ROS on NF-κB and HIF-1α and their pharmacological inhibition suppressed GEM-induced PTX3. Our study findings reinforced the role regarding PTX3 signaling in GEM-induced resistance and pointed toward an unintended and undesired effect of chemotherapy and to get an active regimen; the synergy was associated with NF-κB downregulation in lung cancer.

Molecular changes during extended neoadjuvant letrozole treatment of breast cancer: distinguishing acquired resistance from dormant tumours

BACKGROUND

The risk of recurrence for endocrine-treated breast cancer patients persists for many years or even decades following surgery and apparently successful adjuvant therapy. This period of dormancy and acquired resistance is inherently difficult to investigate; previous efforts have been limited to in-vitro or in-vivo approaches. In this study, sequential tumour samples from patients receiving extended neoadjuvant aromatase inhibitor therapy were characterised as a novel clinical model.

METHODS

Consecutive tumour samples from 62 patients undergoing extended (4-45 months) neoadjuvant aromatase inhibitor therapy with letrozole were subjected to transcriptomic and proteomic analysis, representing before (≤ 0), early (13-120 days), and long-term (> 120 days) neoadjuvant aromatase inhibitor therapy with letrozole. Patients with at least a 40% initial reduction in tumour size by 4 months of treatment were included. Of these, 42 patients with no subsequent progression were classified as "dormant", and the remaining 20 patients as "acquired resistant".

RESULTS

Changes in gene expression in dormant tumours begin early and become more pronounced at later time points. Therapy-induced changes in resistant tumours were common features of treatment, rather than being specific to the resistant phenotype. Comparative analysis of long-term treated dormant and resistant tumours highlighted changes in epigenetics pathways including DNA methylation and histone acetylation. The DNA methylation marks 5-methylcytosine and 5-hydroxymethylcytosine were significantly reduced in resistant tumours compared with dormant tissues after extended letrozole treatment.

CONCLUSIONS

This is the first patient-matched gene expression study investigating long-term aromatase inhibitor-induced dormancy and acquired resistance in breast cancer. Dormant tumours continue to change during treatment whereas acquired resistant tumours more closely resemble their diagnostic samples. Global loss of DNA methylation was observed in resistant tumours under extended treatment. Epigenetic alterations may lead to escape from dormancy and drive acquired resistance in a subset of patients, supporting a potential role for therapy targeted at these epigenetic alterations in the management of resistance to oestrogen deprivation therapy.

Pathways to Endocrine Therapy Resistance in Breast Cancer

Breast cancers with positive expression of Estrogen Receptor (ER+) are treated with anti-hormone/endocrine therapy which targets the activity of the receptor, the half-life of the receptor or the availability of estrogen. This has significantly decreased mortality in women with ER+ breast cancer, however, about 25-30% of treated women run the risk or recurrence due to either intrinsic or acquired resistance to endocrine therapies. While ER itself is a predictor of response to such therapies, there exists a need to find more biomarkers and novel targets to treat resistant tumors. In this review, we summarize the known mechanisms and describe the ability of genomics in unraveling rare mutations and gene rearrangements that may impact the development of resistance and therefore treatment of ER+ breast cancer in the near future.

The evolving role of receptors as predictive biomarkers for metastatic breast cancer

INTRODUCTION

In breast cancer, estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) are essential biomarkers to predict response to endocrine and anti-HER2 therapies, respectively. In metastatic breast cancer, the use of these receptors and targeted therapies present additional challenges: temporal heterogeneity, together with limited sampling methodologies, hinders receptor status assessment, and the constant evolution of the disease invariably leads to resistance to treatment. Areas covered: This review summarizes the genomic abnormalities in ER and HER2, such as mutations, amplifications, translocations, and alternative splicing, emerging as novel biomarkers that provide an insight into underlying mechanisms of resistance and hold potential predictive value to inform treatment selection. We also describe how liquid biopsies for sampling of circulating markers and ultrasensitive detection technologies have emerged which complement ongoing efforts for biomarker discovery and analysis. Expert commentary: While evidence suggests that genomic aberrations in ER and HER2 could contribute to meeting the pressing need for better predictive biomarkers, efforts need to be made to standardize assessment methods and better understand the resistance mechanisms these markers denote. Taking advantage of emerging technologies, research in upcoming years should include prospective trials incorporating these predictors into the study design to validate their potential clinical value.

A novel somatic mutation of SIN3A detected in breast cancer by whole-exome sequencing enhances cell proliferation through ERα expression

Breast cancer is the most frequent tumor in women, and in nearly two-thirds of cases, the tumors express estrogen receptor α (ERα, encoded by ESR1). Here, we performed whole-exome sequencing of 16 breast cancer tissues classified according to ESR1 expression and 12 samples of whole blood, and detected 310 somatic mutations in cancer tissues with high levels of ESR1 expression. Of the somatic mutations validated by a different deep sequencer, a novel nonsense somatic mutation, c.2830 C>T; p.Gln944*, in transcriptional regulator switch-independent 3 family member A (SIN3A) was detected in breast cancer of a patient. Part of the mutant protein localized in the cytoplasm in contrast to the nuclear localization of ERα, and induced a significant increase in ESR1 mRNA. The SIN3A mutation obviously enhanced MCF7 cell proliferation. In tissue sections from the breast cancer patient with the SIN3A c.2830 C>T mutation, cytoplasmic SIN3A localization was detected within the tumor regions where nuclear enlargement was observed. The reduction in SIN3A mRNA correlates with the recurrence of ER-positive breast cancers on Kaplan-Meier plots. These observations reveal that the SIN3A mutation has lost its transcriptional repression function due to its cytoplasmic localization, and that this repression may contribute to the progression of breast cancer.