Cross-talk between HER2 and MED1 regulates tamoxifen resistance of human breast cancer cells

EGR1-BDNF-Linking Crosstalk Between Cancer Cells and Nerves for Perineural Invasion in Salivary Duct Carcinoma: Comparison of Salivary Duct Carcinoma De Novo and Ex Pleomorphic Adenoma

Salivary duct carcinoma (SDC) is primarily categorized as de novo (SDCDN) or ex pleomorphic adenoma (SDCXPA). The incidence of HMGA2 and PLAG1 fusion genes has been suggested to be higher in SDCXPA than in SDCDN. Surgical resection remains the main intervention due to limited guidance on new treatment strategies. However, frequent recurrence and challenging management of metastasis highlight the necessity for innovative treatments. This study aimed to investigate SDC characteristics, including perineural invasion (PNI), and elucidate its carcinogenic mechanisms and adverse prognostic factors. We analyzed 52 patients with SDC diagnosed in the National Cancer Center Hospital from 2014 to 2023. To compare gene expression profiles, we performed immunohistochemical staining, including Her2, adrenergic receptor, PLAG1, and HMGA2, followed by human epidermal growth factor receptor 2 (HER2) in situ hybridization and RNA sequencing of 30 cases. Differential analysis identified genes subjected to immunohistochemical staining and statistical analysis. Based on histologic classification using PLAG1 and HMGA2, 52 cases were classified as 26 cases (50%) SDCDN and 26 cases (50%) SDCXPA. Compared with SDCXPA, SDCDN showed higher perineural, venous, and lymphatic invasion rates (P = .0005, .0294, and .0044, respectively). Genetic expression profiling revealed clustering tendencies between these subtypes. Focusing on PNI, gene expression was decreased in early growth response 1 in tumor portions infiltrating perineural tissues, indicating a negative correlation (P < .0001). Additionally, RNA sequencing showed 3 new fusion genes. In conclusion, clinical disparities between SDCDN and SDCXPA based on molecular and pathological features were observed. We found early growth response 1-brain-derived neurotrophic factor-linking crosstalk between cancer cells and nerves for PNI in SDC, offering insights into future treatment and prognostic factors.

Inhibition of TFF3 synergizes with c-MET inhibitors to decrease the CSC-like phenotype and metastatic burden in ER+HER2+ mammary carcinoma

The interaction between HER2 and ERα signaling pathways contributes to resistance to anti-estrogen and HER2-targeted therapies, presenting substantial treatment challenges in ER-positive (ER+) HER2-positive (HER2+) mammary carcinoma (MC). Trefoil Factor-3 (TFF3) has been reported to mediate resistance to both anti-estrogen and anti-HER2 targeted therapies in ER+ and ER+HER2+ MC, respectively. Herein, the function and mechanism of TFF3 in ER+HER2+ MC were delineated; and novel combinatorial therapeutic strategies were identified. Elevated expression of TFF3 promoted the oncogenicity of ER+HER2+ MC cells, including enhanced cell proliferation, survival, anchorage-independent growth, 3D growth, cancer stem cell-like (CSC-like) phenotype, migration, invasion, and xenograft growth. Targeting TFF3 with an interfering RNA plasmid or a small-molecule inhibitor (AMPC) inhibited these oncogenic characteristics, highlighting the therapeutic potential of targeting TFF3 in ER+HER2+ MC. Furthermore, a high-throughput combinatorial anti-cancer compound library screening revealed that AMPC preferentially synergized with receptor tyrosine kinase c-MET inhibitors (c-METis) to reduce cell survival and the CSC-like phenotype. The combination of AMPC and c-METis also synergistically suppressed the in vivo growth of ER+HER2+ MC cell-derived xenografts and abrogated lung metastasis. Mechanistically, TFF3 was observed to activate c-MET signaling through a positive-feedback loop to enhance the CSC-like phenotype of ER+HER2+ MC. Therefore, proof of concept is provided herein that antagonizing of TFF3 is a promising therapeutic strategy in combination with c-MET inhibition for the treatment of ER+HER2+ MC.

Emerging regulatory mechanisms and functions of biomolecular condensates: implications for therapeutic targets

Cells orchestrate their processes through complex interactions, precisely organizing biomolecules in space and time. Recent discoveries have highlighted the crucial role of biomolecular condensates-membrane-less assemblies formed through the condensation of proteins, nucleic acids, and other molecules-in driving efficient and dynamic cellular processes. These condensates are integral to various physiological functions, such as gene expression and intracellular signal transduction, enabling rapid and finely tuned cellular responses. Their ability to regulate cellular signaling pathways is particularly significant, as it requires a careful balance between flexibility and precision. Disruption of this balance can lead to pathological conditions, including neurodegenerative diseases, cancer, and viral infections. Consequently, biomolecular condensates have emerged as promising therapeutic targets, with the potential to offer novel approaches to disease treatment. In this review, we present the recent insights into the regulatory mechanisms by which biomolecular condensates influence intracellular signaling pathways, their roles in health and disease, and potential strategies for modulating condensate dynamics as a therapeutic approach. Understanding these emerging principles may provide valuable directions for developing effective treatments targeting the aberrant behavior of biomolecular condensates in various diseases.

Crosstalk between 1,25(OH)2-Vitamin D3 and the growth factors EGF and PDGF-BB: Impact on CYP24A1 expression and cell proliferation

This study explored the signaling interplay between the vitamin D receptor (VDR) and receptor tyrosine kinases (RTKs). Epidermal growth factor (EGF) and platelet-derived growth factor (PDGF)-BB promotes cell proliferation in normal and cancer cells. At the same time, the active form of vitamin D (1,25(OH)2-vitamin D3) inhibits proliferation in some cells. Although EGF receptors (EGFR) and PDGF receptors (PDGFR) activate similar downstream pathways, we found that they interact with VDR signaling in distinct ways. We confirmed that 1,25(OH)2-vitamin D3 induces CYP24A1 gene expression in U2OS, T98G, and U251 cells. We found this to be potentiated when combined with EGF. In contrast, PDGF-BB did not impact 1,25(OH)2-vitamin D3-induced CYP24A1 expression in U2OS cells. The increase in CYP24A1 expression due to the combined action of EGF and 1,25(OH)2-vitamin D3 was dependent on AKT and ERK1/2 activation. Another VDR-responsive gene, CYP27B1, was unaffected by the addition of EGF, suggesting that EGF may have gene-specific effects on VDR signaling. While PDGF-BB did not influence CYP24A1 expression, 1,25(OH)2-vitamin D3 significantly influenced PDGF-BB-induced receptor phosphorylation and cell proliferation. In summary, we found that EGF, but not PDGF-BB, influenced the expression of the VDR-dependent gene CYP24A1, while 1,25(OH)2-vitamin D3 had an inhibitory effect on PDGFR signaling and proliferation. These findings highlight unique crosstalk between 1,25(OH)2-vitamin D3 signaling and EGF or PDGF-BB.

miR-205 Regulates Tamoxifen Resistance by Targeting Estrogen Receptor Coactivator MED1 in Human Breast Cancer

Background/Objectives: Estrogen receptor-α coactivator MED1 is overexpressed in 40-60% of human breast cancers, and its high expression correlates with poor disease-free survival of patients undergoing anti-estrogen therapy. However, the molecular mechanism underlying MED1 upregulation and activation in breast cancer treatment resistance remains elusive. Methods: miRNA and mRNA expression analysis was performed using the NCBI GEO database. MED1 targeting and its impact on therapy resistance was evaluated in control and tamoxifen-resistant breast cancer cell lines by miR-205 overexpression and inhibition. Immunoblotting, chromatin immunoprecipitation, and luciferase reporter assays were used to understand the molecular mechanism of MED1-mediated tamoxifen resistance. Mice xenograft models were used to validate treatment efficacy and molecular mechanisms in vivo. Results: miR-205 was found to directly target and suppress the expression of MED1 through bioinformatic analyses and experimental validations. An inverse correlation of miR-205 and MED1 was observed in breast cancer patients with high MED1/low miR-205, indicative of poor prognosis in long-term anti-estrogen treatment. Furthermore, the depletion of miR-205 was observed in tamoxifen-resistant breast cancer cells overexpressing MED1. The restoration of miR-205 expression attenuated MED1 expression and re-sensitized cells to tamoxifen both in vitro and in vivo. Interestingly, miR205 was also found to target another key regulatory gene, HER3, which drives PI3K/Akt signaling and MED1 activation by phosphorylation. Importantly, we found ER target gene transcription and promoter cofactor recruitment by tamoxifen can be reversed by induced miR205 expression. Conclusions: Altogether, miR-205 functions as a negative regulator of MED1 and HER3, affecting the regulation of the HER3-PI3K/Akt-MED1 axis in anti-estrogen resistance, and could serve as a potential therapeutic regime to overcome treatment resistance.

Survival prediction and analysis of drug-resistance genes in HER2-positive breast cancer

Despite the approval of several therapeutic agents for HER2-positive breast cancer, drug resistance remains a significant challenge, hindering the patient's prognosis. Thus, our study aimed to establish a risk model to predict the prognosis of patients and identify key genes regulating drug resistance in HER2-positive breast cancer. Utilizing data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO), a predictive model was constructed based on 5 drug resistance-related genes, which demonstrated a notable capacity to indicate the survival rates of patients. Besides, through eccDNA and transcriptome sequencing of drug-sensitive and resistant cancer cells, 3 significant DEGs were identified: MED1, MED24, and NMD3. Among them, MED1 showed the most significant elevation in drug-resistance cells, highlighting its crucial role in mediating drug resistance. MED1 may serve as a valuable target for alleviating drug resistance in HER2-positive breast cancer.

Mediator complex subunit 1 promotes oral squamous cell carcinoma progression by activating MMP9 transcription and suppressing CD8+ T cell antitumor immunity

BACKGROUND

The role of Mediator complex subunit 1 (MED1), a pivotal transcriptional coactivator implicated in diverse biological pathways, remains unexplored in the context of oral squamous cell carcinoma (OSCC). This study aims to elucidate the contributory mechanisms and potential impact of MED1 on the progression of OSCC.

METHODS

The expression and clinical significance of MED1 in OSCC tissues were evaluated through the bioinformatics analyses. The effects of MED1 on the biological behavior of OSCC cancer cells were assessed both in vitro and in vivo. Dual-luciferase reporter assay, chromatin immunoprecipitation (ChIP) assay, bioinformatic analysis, CD8+ T cell isolation experiment, coculture experiment, enzyme-linked immunosorbent assay (ELISA), and flow cytometric analysis were employed to elucidate the underlying mechanism through which MED1 operates in the progression of OSCC.

RESULTS

MED1 exhibited upregulation in both OSCC tissues and multiple OSCC cell lines, which correlated with decreased overall survival in patients. In vitro experiments demonstrated that knockdown of MED1 in metastatic OSCC cell lines SCC-9 and UPCI-SCC-154 hindered cell migration and invasion, while overexpression of MED1 promoted these processes. Whereas, MED1 knockdown had no impact on proliferation of cell lines mentioned above. In vivo studies further revealed that downregulation of MED1 effectively suppressed distant metastasis in OSCC. Mechanistically, MED1 enhanced the binding of transcription factors c-Jun and c-Fos to the matrix metalloprotein 9 (MMP9) promoters, resulting in a significant upregulation of MMP9 transcription. This process contributes to the migration and invasion of SCC-9 and UPCI-SCC-154 cells. Furthermore, MED1 modulated the expression of programmed death-ligand 1 (PD-L1) through the Notch signaling pathway, consequently impacting the tumor-killing capacity of CD8+ T cells in the tumor microenvironment.

CONCLUSIONS

Our findings indicate that MED1 plays a pivotal role in OSCC progression through the activation of MMP9 transcription and suppression of CD8+ T cell antitumor immunity, suggesting that MED1 may serve as a novel prognostic marker and therapeutic target in OSCC.

Nomograms for predicting recurrence of HER2-positive breast cancer with different HR status based on ultrasound and clinicopathological characteristics

PURPOSE

This study aimed to identify ultrasound and clinicopathological characteristics related to recurrence in HER2-positive (HER2+) breast cancer, and to develop nomograms for predicting recurrence.

METHODS

In this dual-center study, we retrospectively enrolled 570 patients with HER2+ breast cancer. The ultrasound and clinicopathological characteristics of hormone receptor (HR)-/HER2+ patients and HR+/HER2+ patients were analyzed separately according to HR status. Eighty percent of the original samples from HR-/HER2+ and HR+/HER2+ patients were extracted by bootstrap sampling as the training cohorts, while the remaining 20% were used as the external validation cohorts. Informative characteristics were screened through univariate and multivariable Cox regression in the training cohorts and used to develop nomograms for predicting recurrence. The predictive accuracy was calculated using Harrell's C-index and calibration curves.

RESULTS

Three informative characteristics (axillary nodal status, calcification, and Adler degree) were identified in HR-/HER2+ patients, and another three (histological grade, axillary nodal status, and echogenic halo) in HR+/HER2+ patients. Based on these, two separate nomograms were constructed to assess recurrence risk. In the training cohorts, the C-index was 0.740 (95% CI: 0.667-0.811) for HR-/HER2+ nomogram, and 0.749 (95% CI: 0.679-0.820) for HR+/HER2+ nomogram. In the validation cohorts, the C-index was 0.708 (95% CI: 0.540-0.877) for HR-/HER2+ group, and 0.705 (95% CI: 0.557-0.853) for HR+/HER2+ group. The calibration curves also indicated the excellent accuracy of the nomograms.

CONCLUSIONS

Ultrasound performance of HER2+ breast cancers with different HR status was significantly different. Nomograms integrating ultrasound and clinicopathological characteristics exhibited favorable performance and have the potential to serve as a reliable method for predicting recurrence in heterogeneous breast cancer.

Mediator complex in transcription regulation and DNA repair: Relevance for human diseases

The Mediator complex is an essential coregulator of RNA polymerase II transcription. More recent developments suggest Mediator functions as a link between transcription regulation, genome organisation and DNA repair mechanisms including nucleotide excision repair, base excision repair, and homologous recombination. Dysfunctions of these processes are frequently associated with human pathologies, and growing evidence shows Mediator involvement in cancers, neurological, metabolic and infectious diseases. The detailed deciphering of molecular mechanisms of Mediator functions, using interdisciplinary approaches in different biological models and considering all functions of this complex, will contribute to our understanding of relevant human diseases.

Cracking the Code: Enhancing Molecular Tools for Progress in Nanobiotechnology

Nature continually refines its processes for optimal efficiency, especially within biological systems. This article explores the collaborative efforts of researchers worldwide, aiming to mimic nature's efficiency by developing smarter and more effective nanoscale technologies and biomaterials. Recent advancements highlight progress and prospects in leveraging engineered nucleic acids and proteins for specific tasks, drawing inspiration from natural functions. The focus is developing improved methods for characterizing, understanding, and reprogramming these materials to perform user-defined functions, including personalized therapeutics, targeted drug delivery approaches, engineered scaffolds, and reconfigurable nanodevices. Contributions from academia, government agencies, biotech, and medical settings offer diverse perspectives, promising a comprehensive approach to broad nanobiotechnology objectives. Encompassing topics from mRNA vaccine design to programmable protein-based nanocomputing agents, this work provides insightful perspectives on the trajectory of nanobiotechnology toward a future of enhanced biomimicry and technological innovation.

The nuclear export protein exportin-1 in solid malignant tumours: From biology to clinical trials

BACKGROUND

Exportin-1 (XPO1), a crucial protein regulating nuclear-cytoplasmic transport, is frequently overexpressed in various cancers, driving tumor progression and drug resistance. This makes XPO1 an attractive therapeutic target. Over the past few decades, the number of available nuclear export-selective inhibitors has been increasing. Only KPT-330 (selinexor) has been successfully used for treating haematological malignancies, and KPT-8602 (eltanexor) has been used for treating haematologic tumours in clinical trials. However, the use of nuclear export-selective inhibitors for the inhibition of XPO1 expression has yet to be thoroughly investigated in clinical studies and therapeutic outcomes for solid tumours.

METHODS

We collected numerous literatures to explain the efficacy of XPO1 Inhibitors in preclinical and clinical studies of a wide range of solid tumours.

RESULTS

In this review, we focus on the nuclear export function of XPO1 and results from clinical trials of its inhibitors in solid malignant tumours. We summarized the mechanism of action and therapeutic potential of XPO1 inhibitors, as well as adverse effects and response biomarkers.

CONCLUSION

XPO1 inhibition has emerged as a promising therapeutic strategy in the fight against cancer, offering a novel approach to targeting tumorigenic processes and overcoming drug resistance. SINE compounds have demonstrated efficacy in a wide range of solid tumours, and ongoing research is focused on optimizing their use, identifying response biomarkers, and developing effective combination therapies.

KEY POINTS

Exportin-1 (XPO1) plays a critical role in mediating nucleocytoplasmic transport and cell cycle. XPO1 dysfunction promotes tumourigenesis and drug resistance within solid tumours. The therapeutic potential and ongoing researches on XPO1 inhibitors in the treatment of solid tumours. Additional researches are essential to address safety concerns and identify biomarkers for predicting patient response to XPO1 inhibitors.

MED1 induces M2 polarization of tumor-associated macrophages to aggravate breast cancer

BACKGROUND

Breast cancer is a common malignant tumor in female, and its 5-year survival rate remains low. The correlation between mediator subunit 1 (MED1) gene and macrophage phenotypic transformation may be a key factor affecting the therapeutic effect on cancer.

OBJECTIVE

The present study intended to explore the role of MED1 in macrophage polarization and its further influence on the malignant behaviors of breast cancer.

METHODS

Bioinformatics analysis was carried out to predict the expression pattern of MED1 in breast cancer. Flow cytometry was conducted to detect the effect of MED1 overexpression or silencing on macrophage polarization. ELISA was applied to analyze the effect of abnormal MED1 expression on cytokine secretion of macrophages. CCK-8, colony formation, Transwell and scratch healing assays were applied to investigate the effects of macrophage conditioned medium on the malignant behaviors of breast cancer cells.

RESULTS

MED1 expression was prominently increased in M2 macrophages, and overexpression of MED1 significantly increased M2 polarization of tumor-associated macrophages (TAMs) and IL-10 cytokine level. Meanwhile, M2 macrophages with MED1 overexpression could significantly promote the malignant behaviors of breast cancer cells. Dasatinib rescue experiment further confirmed that MED1-induced M2 macrophage polarization could facilitate the malignant progression of breast cancer cells.

CONCLUSION

In summary, MED1 could induce M2 macrophage polarization and thus regulate the malignant behaviors of breast cancer cells.

Transcriptome profiling and network enrichment analyses identify subtype-specific therapeutic gene targets for breast cancer and their microRNA regulatory networks

Previous studies have suggested that breast cancer (BC) from the Middle East and North Africa (MENA) is presented at younger age with advanced tumor stage, indicating underlying biological differences. Given the scant transcriptomic data on BC from the MENA region and to better understand the biology of this disease, we performed mRNA and microRNA (miRNA) transcriptomic profiling on a local cohort of BC (n = 96) from Qatar. Our data revealed the differentially expressed genes and miRNAs as function of BC molecular subtypes (HR⁺, HER2⁺, HER2⁺HR⁺, and TNBC), tumor grade (GIII vs GI-II), patients' age (young (≤40) vs old (>40)), and ethnicity (MENA vs non-MENA). Our profiling data revealed close similarity between TNBC and HER2⁺, while the transcriptome of HER2⁺HR⁺ tumor was resemblant of that from HR⁺ tumors. Network analysis identified complex miRNA-mRNA regulatory networks in each BC molecular subtype, in high vs low grade tumors, in tumors from young vs old patients, and in tumors from MENA vs non-MENA, thus implicating miRNA-mediated gene regulation as an essential mechanism in shaping the transcriptome of BC. Integration of our transcriptomic data with CRISPR-Cas9 functional screen data and the OncoKB database identified numerous dependencies and therapeutic vulnerabilities in each BC molecular subtype, while CDC123 was functionally validated as potential therapeutic target for TNBC. Cox regression survival analyses identified mRNA and miRNA-based signatures predicative of worse and better relapse free survival (RFS), which were validated in larger BC cohorts. Our data provides comprehensive transcriptomic profiling and unraveled the miRNA-mRNA regulatory networks in BC patients from the region and identified novel actionable gene targets, employing integrated approach. Findings from the current study have potential implications to improve the current standard-of-care for BC from the MENA as well as patients from other ethnicities.

Phase separation in cancer at a glance

Eukaryotic cells are segmented into multiple compartments or organelles within the cell that regulate distinct chemical and biological processes. Membrane-less organelles are membrane-less microscopic cellular compartments that contain protein and RNA molecules that perform a wide range of functions. Liquid-liquid phase separation (LLPS) can reveal how membrane-less organelles develop via dynamic biomolecule assembly. LLPS either segregates undesirable molecules from cells or aggregates desired ones in cells. Aberrant LLPS results in the production of abnormal biomolecular condensates (BMCs), which can cause cancer. Here, we explore the intricate mechanisms behind the formation of BMCs and its biophysical properties. Additionally, we discuss recent discoveries related to biological LLPS in tumorigenesis, including aberrant signaling and transduction, stress granule formation, evading growth arrest, and genomic instability. We also discuss the therapeutic implications of LLPS in cancer. Understanding the concept and mechanism of LLPS and its role in tumorigenesis is crucial for antitumor therapeutic strategies.

Proximity labeling reveals a new in vivo network of interactors for the histone demethylase KDM5

BACKGROUND

KDM5 family proteins are multi-domain regulators of transcription that when dysregulated contribute to cancer and intellectual disability. KDM5 proteins can regulate transcription through their histone demethylase activity in addition to demethylase-independent gene regulatory functions that remain less characterized. To expand our understanding of the mechanisms that contribute to KDM5-mediated transcription regulation, we used TurboID proximity labeling to identify KDM5-interacting proteins.

RESULTS

Using Drosophila melanogaster, we enriched for biotinylated proteins from KDM5-TurboID-expressing adult heads using a newly generated control for DNA-adjacent background in the form of dCas9:TurboID. Mass spectrometry analyses of biotinylated proteins identified both known and novel candidate KDM5 interactors, including members of the SWI/SNF and NURF chromatin remodeling complexes, the NSL complex, Mediator, and several insulator proteins.

CONCLUSIONS

Combined, our data shed new light on potential demethylase-independent activities of KDM5. In the context of KDM5 dysregulation, these interactions may play key roles in the alteration of evolutionarily conserved transcriptional programs implicated in human disorders.

Recent advances in targeted gene silencing and cancer therapy by nanoparticle-based delivery systems

Nanomedicine has emerged as a promising platform for disease treatment and much progress has been achieved in the clinical translation for cancer treatment. Several types of nanomedicines have been approved for therapeutic application. However, many nanoparticles still suffer from challenges in the translation from bench to bedside. Currently, nanoparticle-based delivery systems have been developed to explore their functions in targeted gene silencing and cancer therapy. This review describes the research progress of different nano-carriers in targeted gene editing, and the recent progress in co-delivery of anticancer drugs and small ribonucleic acid. We also summarize the strategies for improving the specificity of carrier systems. Finally, we discuss the functions of targeted nano-carriers in overcoming chemotherapeutic drug resistance in cancer therapy. As research continues to advance, a better understanding of the safety including long-term toxicity, immunogenicity, and body metabolism may impel nanoparticle translation.

The crucial role of epigenetic regulation in breast cancer anti-estrogen resistance: Current findings and future perspectives

Breast cancer (BC) cell de-sensitization to Tamoxifen (TAM) or other selective estrogen receptor (ER) modulators (SERM) is a complex process associated with BC heterogeneity and the transformation of ER signalling. The most influential resistance-related mechanisms include modifications in ER expression and gene regulation patterns. During TAM/SERM treatment, epigenetic mechanisms can effectively silence ER expression and facilitate the development of endocrine resistance. ER status is efficiently regulated by specific epigenetic tools including hypermethylation of CpG islands within ER promoters, increased histone deacetylase activity in the ER promoter, and/or translational repression by miRNAs. Over-methylation of the ER α gene (ESR1) promoter by DNA methyltransferases was associated with poor prognosis and indicated the development of resistance. Moreover, BC progression and spreading were marked by transformed chromatin remodelling, post-translational histone modifications, and expression of specific miRNAs and/or long non-coding RNAs. Therefore, targeted inhibition of histone acetyltransferases (e.g. MYST3), deacetylases (e.g. HDAC1), and/or demethylases (e.g. lysine-specific demethylase LSD1) was shown to recover and increase BC sensitivity to anti-estrogens. Indicated as a powerful molecular instrument, the administration of epigenetic drugs can regain ER expression along with the activation of tumour suppressor genes, which can in turn prevent selection of resistant cells and cancer stem cell survival. This review examines recent advances in the epigenetic regulation of endocrine drug resistance and evaluates novel anti-resistance strategies. Underlying molecular mechanisms of epigenetic regulation will be discussed, emphasising the utilization of epigenetic enzymes and their inhibitors to re-program irresponsive BCs.

Transcriptional coactivator MED1 in the interface of anti-estrogen and anti-HER2 therapeutic resistance

Breast cancer is one of the most common cancer and leading causes of death in women in the United States and Worldwide. About 90% of breast cancers belong to ER+ or HER2+ subtypes and are driven by key breast cancer genes Estrogen Receptor and HER2, respectively. Despite the advances in anti-estrogen (endocrine) and anti-HER2 therapies for the treatment of these breast cancer subtypes, unwanted side effects, frequent recurrence and resistance to these treatments remain major clinical challenges. Recent studies have identified ER coactivator MED1 as a key mediator of ER functions and anti-estrogen treatment resistance. Interestingly, MED1 is also coamplified with HER2 and activated by the HER2 signaling cascade, and plays critical roles in HER2-mediated tumorigenesis and response to anti-HER2 treatment as well. Thus, MED1 represents a novel crosstalk point of the HER2 and ER pathways and a highly promising new therapeutic target for ER+ and HER2+ breast cancer treatment. In this review, we will discuss the recent progress on the role of this key ER/HER2 downstream effector MED1 in breast cancer therapy resistance and our development of an innovative RNA nanotechnology-based approach to target MED1 for potential future breast cancer therapy to overcome treatment resistance.

Role of the Mediator Complex and MicroRNAs in Breast Cancer Etiology

Transcriptional coactivators play a key role in RNA polymerase II transcription and gene regulation. One of the most important transcriptional coactivators is the Mediator (MED) complex, which is an evolutionary conserved large multiprotein complex. MED transduces the signal between DNA-bound transcriptional activators (gene-specific transcription factors) to the RNA polymerase II transcription machinery to activate transcription. It is known that MED plays an essential role in ER-mediated gene expression mainly through the MED1 subunit, since estrogen receptor (ER) can interact with MED1 by specific protein–protein interactions; therefore, MED1 plays a fundamental role in ER-positive breast cancer (BC) etiology. Additionally, other MED subunits also play a role in BC etiology. On the other hand, microRNAs (miRNAs) are a family of small non-coding RNAs, which can regulate gene expression at the post-transcriptional level by binding in a sequence-specific fashion at the 3′ UTR of the messenger RNA. The miRNAs are also important factors that influence oncogenic signaling in BC by acting as both tumor suppressors and oncogenes. Moreover, miRNAs are involved in endocrine therapy resistance of BC, specifically to tamoxifen, a drug that is used to target ER signaling. In metazoans, very little is known about the transcriptional regulation of miRNA by the MED complex and less about the transcriptional regulation of miRNAs involved in BC initiation and progression. Recently, it has been shown that MED1 is able to regulate the transcription of the ER-dependent miR-191/425 cluster promoting BC cell proliferation and migration. In this review, we will discuss the role of MED1 transcriptional coactivator in the etiology of BC and in endocrine therapy-resistance of BC and also the contribution of other MED subunits to BC development, progression and metastasis. Lastly, we identified miRNAs that potentially can regulate the expression of MED subunits.

CDK7 Predicts Worse Outcome in Head and Neck Squamous-Cell Cancer

HNSCC is the sixth most common cancer worldwide and the prognosis is still poor. Here, we investigated the prognostic implications of CDK7 and pMED1. Both proteins affect transcription, and their expression is altered throughout different tumor entities. pMED1 is phosphorylated by CDK7. Importantly, CDK7 and MED1 have been ascribed prognostic implications by various studies. However, their prognostic value in head and neck squamous-cell cancer (HNSCC) remains elusive. We applied immunohistochemical staining of CDK7 and pMED1 on our large and clinically well-characterized HNSCC tissue cohort comprising 419 patients. Software-aided quantification of staining intensity was performed as a measure of protein expression. The following results were linked to the clinicopathological features of our cohort and correlated in different tissue types (primary tumor, lymph node metastasis, distant metastasis, recurrence). Upregulation CDK7 was associated with worse 5-year overall survival as well as disease-free survival in HNSCC while being independent of other known prognostic factors such as p16-status. Also, CDK7 expression was significantly elevated in immune cell infiltrated tumors. In HNSCC CDK7 might serve as a novel prognostic marker to indicate the prognosis of patients. Furthermore, in vitro studies proved the feasibility of CDK7 inhibition with attenuating effects on cell proliferation underlining its remarkable translational potential for future therapeutic regimes.

MED10 Drives the Oncogenicity and Refractory Phenotype of Bladder Urothelial Carcinoma Through the Upregulation of hsa-miR-590

BACKGROUND

Dysfunctional transcription machinery with associated dysregulated transcription characterizes many malignancies. Components of the mediator complex, a principal modulator of transcription, are increasingly implicated in cancer. The mediator complex subunit 10 (MED10), a vital kinase module of the mediator, plays a critical role in bladder physiology and pathology. However, its role in the oncogenicity, metastasis, and disease recurrence in bladder cancer (BLCA) remains unclear.

OBJECTIVE

Thus, we investigated the role of dysregulated or aberrantly expressed MED10 in the enhanced onco-aggression, disease progression, and recurrence of bladder urothelial carcinoma (UC), as well as the underlying molecular mechanism.

METHODS

Using an array of multi-omics big data analyses of clinicopathological data, in vitro expression profiling and functional assays, and immunocytochemical staining, we assessed the probable roles of MED10 in the progression and prognosis of BLCA/UC.

RESULTS

Our bioinformatics-aided gene expression profiling showed that MED10 is aberrantly expressed in patients with BLCA, is associated with high-grade disease, is positively correlated with tumor stage, and confers significant survival disadvantage. Reanalyzing the TCGA BLCA cohort (n = 454), we showed that aberrantly expressed MED10 expression is associated with metastatic and recurrent disease, disease progression, immune suppression, and therapy failure. Interestingly, we demonstrated that MED10 interacts with and is co-expressed with the microRNA, hsa-miR-590, and that CRISPR-mediated knockout of MED10 elicits the downregulation of miR-590 preferentially in metastatic UC cells, compared to their primary tumor peers. More so, silencing MED10 in SW1738 and JMSU1 UC cell lines significantly attenuates their cell proliferation, migration, invasion, clonogenicity, and tumorsphere formation (primary and secondary), with the associated downregulation of BCL-xL, MKI67, VIM, SNAI1, OCT4, and LIN28A but upregulated BAX protein expression. In addition, we showed that high MED10 expression is a non-inferior biomarker of urothelial recurrence compared with markers of cancer stemness; however, MED10 is a better biomarker of local recurrence than any of the stemness markers.

CONCLUSION

These data provide preclinical evidence that dysregulated MED10/MIR590 signaling drives onco-aggression, disease progression, and recurrence of bladder UC and that this oncogenic signal is therapeutically actionable for repressing the metastatic/recurrent phenotypes, enhancing therapy response, and shutting down stemness-driven disease progression and relapse in patients with BLCA/UC.

HIF1α and p53 Regulated MED30, a Mediator Complex Subunit, is Involved in Regulation of Glioblastoma Pathogenesis and Temozolomide Resistance

Glioblastoma (GBM) is the most common, malignant, and aggressive form of glial cell cancer with unfavorable clinical outcomes. It is believed that a better understanding of the mechanisms of gene deregulation may lead to novel therapeutic approaches for this yet incurable cancer. Mediator complex is a crucial component of enhancer-based gene expression and works as a transcriptional co-activator. Many of the mediator complex subunits are found to be deregulated/mutated in various malignancies; however, their status and role in GBM remains little studied. We report that MED30, a core subunit of the head module, is overexpressed in GBM tissues and cell lines. MED30 was found to be induced by conditions present in the tumor microenvironment such as hypoxia, serum, and glucose deprivation. MED30 harbors hypoxia response elements (HREs) and p53 binding site in its promoter and is induced in a HIF1α and p53 dependent manner. Further, MED30 levels also significantly positively correlated with p53 and HIF1α levels in GBM tissues. Using both MED30 overexpression and knockdown approach, we show that MED30 promotes cell proliferation while reduces the migration capabilities in GBM cell lines. Notably, MED30 was also found to confer sensitivity to chemodrug, temozolomide, in GBM cells and modulate the level of p53 in vitro. Overall, this is the first report showing MED30 overexpression in GBM and its involvement in GBM pathogenesis suggesting its diagnostic and therapeutic potential urging the need for further systematic exploration of MED30 interactome and target networks.

Mediator subunit MED1 is required for E2A-PBX1-mediated oncogenic transcription and leukemic cell growth

The chimeric transcription factor E2A-PBX1, containing the N-terminal activation domains of E2A fused to the C-terminal DNA-binding domain of PBX1, results in 5% of pediatric acute lymphoblastic leukemias (ALL). We recently have reported a mechanism for RUNX1-dependent recruitment of E2A-PBX1 to chromatin in pre-B leukemic cells; but the subsequent E2A-PBX1 functions through various coactivators and the general transcriptional machinery remain unclear. The Mediator complex plays a critical role in cell-specific gene activation by serving as a key coactivator for gene-specific transcription factors that facilitates their function through the RNA polymerase II transcriptional machinery, but whether Mediator contributes to aberrant expression of E2A-PBX1 target genes remains largely unexplored. Here we show that Mediator interacts directly with E2A-PBX1 through an interaction of the MED1 subunit with an E2A activation domain. Results of MED1 depletion by CRISPR/Cas9 further indicate that MED1 is specifically required for E2A-PBX1-dependent gene activation and leukemic cell growth. Integrated transcriptome and cistrome analyses identify pre-B cell receptor and cell cycle regulatory genes as direct cotargets of MED1 and E2A-PBX1. Notably, complementary biochemical analyses also demonstrate that recruitment of E2A-PBX1 to a target DNA template involves a direct interaction with DNA-bound RUNX1 that can be further stabilized by EBF1. These findings suggest that E2A-PBX1 interactions with RUNX1 and MED1/Mediator are of functional importance for both gene-specific transcriptional activation and maintenance of E2A-PBX1-driven leukemia. The MED1 dependency for E2A-PBX1-mediated gene activation and leukemogenesis may provide a potential therapeutic opportunity by targeting MED1 in E2A-PBX1⁺ pre-B leukemia.

Functional cooperation between co-amplified genes promotes aggressive phenotypes of HER2-positive breast cancer

MED1 (mediator subunit 1)co-amplifies with HER2, but its role in HER2-driven mammary tumorigenesis is still unknown. Here, we generate MED1 mammary-specific overexpression mice and cross them with mouse mammary tumor virus (MMTV)-HER2 mice. We observe significantly promoted onset, growth, metastasis, and multiplicity of HER2 tumors by MED1 overexpression. Further studies reveal critical roles for MED1 in epithelial-mesenchymal transition, cancer stem cell formation, and response to anti-HER2 therapy. Mechanistically, RNA sequencing (RNA-seq) transcriptome analyses and clinical sample correlation studies identify Jab1, a component of the COP9 signalosome complex, as the key direct target gene of MED1 contributing to these processes. Further studies reveal that Jab1 can also reciprocally regulate the stability and transcriptional activity of MED1. Together, our findings support a functional cooperation between these co-amplified genes in HER2⁺ mammary tumorigenesis and their potential usage as therapeutic targets for the treatment of HER2⁺ breast cancers.

In this study, Yang et al. generate a more clinically relevant MMTV-HER2/MMTV-MED1 mammary tumor mouse model and discover the critical roles and molecular mechanisms of MED1 overexpression in mediating the aggressive phenotypes of HER2⁺ tumor progression, metastasis, cancer stem cell formation, and therapy resistance.

Classifying Breast Cancer Subtypes Using Deep Neural Networks Based on Multi-Omics Data

With the high prevalence of breast cancer, it is urgent to find out the intrinsic difference between various subtypes, so as to infer the underlying mechanisms. Given the available multi-omics data, their proper integration can improve the accuracy of breast cancer subtype recognition. In this study, DeepMO, a model using deep neural networks based on multi-omics data, was employed for classifying breast cancer subtypes. Three types of omics data including mRNA data, DNA methylation data, and copy number variation (CNV) data were collected from The Cancer Genome Atlas (TCGA). After data preprocessing and feature selection, each type of omics data was input into the deep neural network, which consists of an encoding subnetwork and a classification subnetwork. The results of DeepMO based on multi-omics on binary classification are better than other methods in terms of accuracy and area under the curve (AUC). Moreover, compared with other methods using single omics data and multi-omics data, DeepMO also had a higher prediction accuracy on multi-classification. We also validated the effect of feature selection on DeepMO. Finally, we analyzed the enrichment gene ontology (GO) terms and biological pathways of these significant genes, which were discovered during the feature selection process. We believe that the proposed model is useful for multi-omics data analysis.

A novel tumor suppressor ZBTB1 regulates tamoxifen resistance and aerobic glycolysis through suppressing HER2 expression in breast cancer

Transcriptional repressor zinc finger and BTB domain containing 1 (ZBTB1) is required for DNA repair. Because DNA repair defects often underlie genome instability and tumorigenesis, we determined to study the role of ZBTB1 in cancer. In this study, we found that ZBTB1 is down-regulated in breast cancer and this down-regulation is associated with poor outcome of breast cancer patients. ZBTB1 suppresses breast cancer cell proliferation and tumor growth. The majority of breast cancers are estrogen receptor (ER) positive and selective estrogen receptor modulators such as tamoxifen have been widely used in the treatment of these patients. Unfortunately, many patients develop resistance to endocrine therapy. Tamoxifen-resistant cancer cells often exhibit higher HER2 expression and an increase of glycolysis. Our data revealed that ZBTB1 plays a critical role in tamoxifen resistance in vitro and in vivo To see if ZBTB1 regulates HER2 expression, we tested the recruitments of ZBTB1 on HER2 regulatory sequences. We observed that over-expressed ZBTB1 occupies the estrogen receptor α (ERα)-binding site of the HER2 intron in tamoxifen-resistant cells, suppressing tamoxifen-induced transcription. In an effort to identify potential microRNAs (miRNAs) regulating ZBTB1, we found that miR-23b-3p directly targets ZBTB1. MiR-23b-3p regulates HER2 expression and tamoxifen resistance via targeting ZBTB1. Finally, we found that miR-23b-3p/ZBTB1 regulates aerobic glycolysis in tamoxifen-resistant cells. Together, our data demonstrate that ZBTB1 is a tumor suppressor in breast cancer cells and that targeting the miR-23b-3p/ZBTB1 may serve as a potential therapeutic approach for the treatment of tamoxifen resistant breast cancer.

Partitioning of cancer therapeutics in nuclear condensates

The nucleus contains diverse phase-separated condensates that compartmentalize and concentrate biomolecules with distinct physicochemical properties. Here, we investigated whether condensates concentrate small-molecule cancer therapeutics such that their pharmacodynamic properties are altered. We found that antineoplastic drugs become concentrated in specific protein condensates in vitro and that this occurs through physicochemical properties independent of the drug target. This behavior was also observed in tumor cells, where drug partitioning influenced drug activity. Altering the properties of the condensate was found to affect the concentration and activity of drugs. These results suggest that selective partitioning and concentration of small molecules within condensates contributes to drug pharmacodynamics and that further understanding of this phenomenon may facilitate advances in disease therapy.

Although c‑MYC contributes to tamoxifen resistance, it improves cisplatin sensitivity in ER‑positive breast cancer

Tamoxifen (TAM) resistance is a major challenge in the treatment of estrogen receptor‑positive (ER+) breast cancer. To date, to the best of our knowledge, there are only a few studies available examining the response of patients with TAM‑resistant breast cancer to chemotherapy, and the guidelines do not specify recommended drugs for these patients. In the present study, TAM‑resistant cells were shown to exhibit increased proliferation and invasion compared with the parent cells, and the increased expression of c‑MYC was demonstrated to play an important role in TAM resistance. Furthermore, the TAM‑resistant cells were significantly more sensitive to cisplatin compared with the parent cells, and the silencing of c‑MYC expression desensitized the cells to cisplatin through the inhibition of the cell cycle. An increased c‑MYC expression was observed in 28 pairs of primary and metastatic tumors from patients treated with TAM, and the clinical remission rate of cisplatin‑based chemotherapy was significantly higher compared with other chemotherapy‑based regimens in 122 patients with TAM resistant breast cancer. Taken together, the data of the present study demonstrated that although c‑MYC was involved in TAM resistance, it increased the sensitivity of ER+ breast cancer to cisplatin. Thus, cisplatin may be a preferred chemotherapeutic agent for the treatment of patients with TAM‑resistant breast cancer, particularly in patients where the rapid control of disease progression is required.

Role of MEL-18 Amplification in Anti-HER2 Therapy of Breast Cancer

BACKGROUND

Resistance to HER2-targeted therapy with trastuzumab still remains a major challenge in HER2-amplified tumors. Here we investigated the potential role of MEL-18, a polycomb group gene, as a novel prognostic marker for trastuzumab resistance in HER2-positive (HER2+) breast cancer.

METHODS

The genetic alteration of MEL-18 and its clinical relevance were examined in multiple breast cancer cohorts including METABRIC (n = 1,980), TCGA (n = 825), and our clinical specimens (n = 213, trastuzumab-treated HER2+ cases). MEL-18 amplification was validated by fluorescence in situ hybridization (FISH) analysis. The MEL-18 effect on trastuzumab response was confirmed by in vitro cell viability assays and an in vivo xenograft experiment (n = 7 per group). Gene expression microarray and receptor tyrosine kinase array were performed to identify the trastuzumab resistance mechanism by MEL-18 loss. All statistical tests were two-sided.

RESULTS

MEL-18 was exclusively amplified in approximately 30-50% of HER2+ breast tumors and was associated with a favorable clinical outcome (disease-free survival: P = .02 in HER2+ cases, METABRIC; P = .04 in patients receiving trastuzumab). In MEL-18-amplified HER2+ breast cancer, MEL-18 depletion induced trastuzumab resistance by increasing ADAM sheddase-mediated ErbB ligand production and receptor heterodimerization. MEL-18 epigenetically silenced ADAM10/17 expression in cooperation with polycomb-repressive complex (PRC) 1 and PRC2. Combination treatment with an ADAM10/17 inhibitor and trastuzumab could overcome MEL-18 loss-mediated trastuzumab resistance in vivo (BT474/shMEL-18 xenograft: trastuzumab, mean [SD] tumor volume = 406.1 [50.1] mm3, vs trastuzumab + GW280264 30 mg/kg, mean [SD] tumor volume = 68.4 [15.6] mm3, P < .001). Consistently, trastuzumab-treated patients harboring concomitant MEL-18 amplification and low ADAM17 expression showed prolonged relapse-free survival (P = .02 in our cohort, n = 213).

CONCLUSION

MEL-18 serves to prevent ligand-dependent ErbB heterodimerization and trastuzumab resistance, suggesting MEL-18 amplification as a novel biomarker for HER2+ breast cancer.

Estrogen receptor coactivator Mediator Subunit 1 (MED1) as a tissue-specific therapeutic target in breast cancer

Breast cancer, one of the most frequent cancer types, is a leading cause of death in women worldwide. Estrogen receptor (ER) α is a nuclear hormone receptor that plays key roles in mammary gland development and breast cancer. About 75% of breast cancer cases are diagnosed as ER-positive; however, nearly half of these cancers are either intrinsically or inherently resistant to the current anti-estrogen therapies. Recent studies have identified an ER coactivator, Mediator Subunit 1 (MED1), as a unique, tissue-specific cofactor that mediates breast cancer metastasis and treatment resistance. MED1 is overexpressed in over 50% of human breast cancer cases and co-amplifies with another important breast cancer gene, receptor tyrosine kinase HER2. Clinically, MED1 expression highly correlates with poor disease-free survival of breast cancer patients, and recent studies have reported an increased frequency of MED1 mutations in the circulating tumor cells of patients after treatment. In this review, we discuss the biochemical characterization of MED1 and its associated MED1/Mediator complex, its crosstalk with HER2 in anti-estrogen resistance, breast cancer stem cell formation, and metastasis both in vitro and in vivo. Furthermore, we elaborate on the current advancements in targeting MED1 using state-of-the-art RNA nanotechnology and discuss the future perspectives as well.

A functional genetic screen identifies the Mediator complex as essential for SSX2-induced senescence

The senescence response to oncogenes is believed to be a barrier to oncogenic transformation in premalignant lesions, and describing the mechanisms by which tumor cells evade this response is important for early diagnosis and treatment. The male germ cell-associated protein SSX2 is ectopically expressed in many types of cancer and is functionally involved in regulating chromatin structure and supporting cell proliferation. Similar to many well-characterized oncogenes, SSX2 has the ability to induce senescence in cells. In this study, we performed a functional genetic screen to identify proteins implicated in SSX2-induced senescence and identified several subunits of the Mediator complex, which is central in regulating RNA polymerase-mediated transcription. Further experiments showed that reduced levels of MED1, MED4, and MED14 perturbed the development of senescence in SSX2-expressing cells. In contrast, knockdown of MED1 did not prevent development of B-Raf- and Epirubicin-induced senescence, suggesting that Mediator may be specifically linked to the cellular functions of SSX2 that may lead to development of senescence or be central in a SSX2-specific senescence response. Indeed, immunostaining of melanoma tumors, which often express SSX proteins, exhibited altered levels of MED1 compared to benign nevi. Similarly, RNA-seq analysis suggested that MED1, MED4, and MED14 were downregulated in some tumors, while upregulated in others. In conclusion, our study reveals the Mediator complex as essential for SSX2-induced senescence and suggests that changes in Mediator activity could be instrumental for tumorigenesis.

The Central Contributions of Breast Cancer Stem Cells in Developing Resistance to Endocrine Therapy in Estrogen Receptor (ER)-Positive Breast Cancer

Breast cancer stem cells (BCSC) play critical roles in the acquisition of resistance to endocrine therapy in estrogen receptor (ER)-positive (ER + ve) breast cancer (BC). The resistance results from complex alterations involving ER, growth factor receptors, NOTCH, Wnt/β-catenin, hedgehog, YAP/TAZ, and the tumor microenvironment. These mechanisms are likely converged on regulating BCSCs, which then drive the development of endocrine therapy resistance. In this regard, hormone therapies enrich BCSCs in ER + ve BCs under both pre-clinical and clinical settings along with upregulation of the core components of “stemness” transcriptional factors including SOX2, NANOG, and OCT4. SOX2 initiates a set of reactions involving SOX9, Wnt, FXY3D, and Src tyrosine kinase; these reactions stimulate BCSCs and contribute to endocrine resistance. The central contributions of BCSCs to endocrine resistance regulated by complex mechanisms offer a unified strategy to counter the resistance. ER + ve BCs constitute approximately 75% of BCs to which hormone therapy is the major therapeutic approach. Likewise, resistance to endocrine therapy remains the major challenge in the management of patients with ER + ve BC. In this review we will discuss evidence supporting a central role of BCSCs in developing endocrine resistance and outline the strategy of targeting BCSCs to reduce hormone therapy resistance.

The potential markers of endocrine resistance among HR+ /HER2+ breast cancer patients

PURPOSE

Breast cancer with positive hormone receptor (HR) and human epidermal growth factor receptor-2 (HER2) is a special subgroup with different clinical features and survival, especially the endocrine therapy resistance. The main purpose of the study is to find the potential markers to predict the survival and endocrine therapy resistance of patients with HR+ /HER2+ breast cancer.

METHODS

Surveillance, Epidemiology, and End Results (SEER) database was used to collect patients' clinical information and tumor features including age, tumor size, grade, stage and long-term survival; the BioPortal for Cancer Genomics (https://cbioportal.org) was used to download the gene data for specific patient group; cluster analyses of gene expression were conducted through the DAVID Bioinformatics Resources 6.8 software.

RESULTS

All of the included patients were diagnosed as HR positive breast cancer, but the PR positive rates were more common in HER2- group and also the ER+ /PR+ disease. Patients in HR+ /HER2+ group were more likely to present as stage III-IV and grade III disease. Among HR+ /HER2+ patients, 68.6% received chemotherapy, while only 28.9% in HR+ /HER2- group received chemotherapy (P < 0.0001). The survival of HR+ /HER2+ group was poorer. From TCGA database, series genes which were differed between HR+ /HER2+ and HR+ /HER2- were screened out that related to ERBB2 closely: IKZF3, LASP1, CDK12, MLLT6, and RARA. The first three candidate genes were associated with patients' survival, especially in patients who received hormone therapies.

CONCLUSION

This study analyzed the clinical characteristics and survival of patients with HR+/HER2+ breast cancer as a special subgroup. ERBB2, IKZF3, LASP1, and CDK12 were the potential markers of the resistance of endocrine therapy, and they will provide new strategies for clinicians.

Nucleic Acid-Based Functional Nanomaterials as Advanced Cancer Therapeutics

Nucleic acid-based functional nanomaterials (NAFN) have been widely used as emerging drug delivery nanocarriers for cancer therapeutics. Considerable works have demonstrated that NAFN can effectively load and protect therapeutic agents, and particularly enable targeting delivery to the tumor site and stimuli-responsive release. These outstanding performances are due to NAFN's unique properties including inherent biological functions and sequence programmability as well as biocompatibility and biodegradability. In this Review, the recent progress on NAFN as advanced cancer therapeutics is highlighted. Three main cancer therapy approaches are categorized including chemo-, immuno-, and gene-therapy. Examples are presented to show how NAFN are rationally and exquisitely designed to address problems in cancer therapy. The challenges and future development of NAFN are also discussed toward future more practical biomedical applications.

A temperature-sensitive phase-change hydrogel of tamoxifen achieves the long-acting antitumor activation on breast cancer cells

Background: Breast cancer is one of the foremost threats to female health nowadays. Tamoxifen, an antagonist of estrogen receptor-α (ERα), is the first choice for endocrine-dependent breast cancer (ERα-positive breast cancer) treatment. However, ERα has an important function in the normal physical regulation of estrogen, and current oral administration of tamoxifen has potential side effects on normal endocrine secretion. In the present work, we aim to develop novel approaches to increase the antitumor effect of tamoxifen on breast cancer cells and decrease the potential side effects in the human body during treatment. Methods: A temperature-sensitive phase-change hydrogel for tamoxifen (Tam-Gel) was generated. After establishing subcutaneous tumors formed by MCF-7, an ERα-positive breast cancer cell line, in nude mice, an intratumoral injection of Tam-Gel was performed to examine whether Tam-Gel facilitated the slow-release or antitumor effect of tamoxifen. A metastatic breast cancer model was established using the intrahepatic growth of MCF-7 cells in immunodeficient rats. Results: Tam-Gel can transform from liquid to hydrogel at room temperature. An intratumoral injection of Tam-Gel facilitated the slow-release or antitumor effect of tamoxifen. Once Tam-Gel, but not Tam-Sol, was administered by intratumoral injection, it significantly decreased the uptake of radionuclide probes (¹⁸F-fluoroestradiol or ¹⁸F-fluorodeoxyglucose) by cells in rats' livers and the intrahepatic growth of MCF-7 cells in rats' livers. Conclusion: A novel slow-release system was successfully prepared to facilitate the long-term release of tamoxifen in breast cancer tissues, and achieved an antitumor effect in the long term.

Norcantharidin regulates ERα signaling and tamoxifen resistance via targeting miR-873/CDK3 in breast cancer cells

MiR-873/CDK3 has been shown to play a critical role in ERα signaling and tamoxifen resistance. Thus, targeting this pathway may be a potential therapeutic approach for the treatment of ER positive breast cancer especially tamoxifen resistant subtype. Here we report that Norcantharidin (NCTD), currently used clinically as an ani-cancer drug in China, regulates miR-873/CDK3 axis in breast cancer cells. NCTD decreases the transcriptional activity of ERα but not ERβ through the modulation of miR-873/CDK3 axis. We also found that NCTD inhibits cell proliferation and tumor growth and miR-873/CDK3 axis mediates cell proliferation suppression of NCTD. More important, we found that NCTD sensitizes resistant cells to tamoxifen. NCTD inhibits tamoxifen induced the transcriptional activity as well ERα downstream gene expressions in tamoxifen resistant breast cancer cells. In addition, we found that NCTD restores tamoxifen induced recruitments of ERα co-repressors N-CoR and SMRT. Knockdown of miR-873 and overexpression of CDK3 diminish the effect of NCTD on tamoxifen resistance. Our data shows that NCTD regulates ERα signaling and tamoxifen resistance by targeting miR-873/CDK3 axis in breast cancer cells. This study may provide an alternative therapy strategy for tamoxifen resistant breast cancer.

Novel insights into the role of aptamers in the fight against cancer

PURPOSE

Aptamers are a class of single-stranded nucleic acid (DNA or RNA) oligonucleotides that are screened in vitro by a technique called systematic evolution of ligands by exponential enrichment (SELEX). They have stable three-dimensional structures that can bind to various targets with high affinity and specificity. Due to distinct properties such as easy synthesis, high stability, small size, low toxicity and immunogenicity, they have been largely studied as anticancer agents/tools. Consequently, aptamers are starting to play important roles in disease prevention, diagnosis and therapy. This review focuses on studies that evaluated the effect of aptamers on various aspects of cancer therapy. It also provides novel and unique insights into the role of aptamers on the fight against cancer.

METHODS

We reviewed literatures about the role of aptamers against cancer from PUBMED databases in this article.

RESULTS

Here, we summarized the role of aptamers on the fight against cancer in a unique point of view. Meanwhile, we presented novel ideas such as aptamer-pool-drug conjugates for the treatment of refractory cancers.

CONCLUSIONS

Aptamers and antibodies should form a "coalition" against cancers to maximize their advantages and minimize disadvantages.

Classifying Breast Cancer Subtypes Using Multiple Kernel Learning Based on Omics Data

It is very significant to explore the intrinsic differences in breast cancer subtypes. These intrinsic differences are closely related to clinical diagnosis and designation of treatment plans. With the accumulation of biological and medicine datasets, there are many different omics data that can be viewed in different aspects. Combining these multiple omics data can improve the accuracy of prediction. Meanwhile; there are also many different databases available for us to download different types of omics data. In this article, we use estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) to define breast cancer subtypes and classify any two breast cancer subtypes using SMO-MKL algorithm. We collected mRNA data, methylation data and copy number variation (CNV) data from TCGA to classify breast cancer subtypes. Multiple Kernel Learning (MKL) is employed to use these omics data distinctly. The result of using three omics data with multiple kernels is better than that of using single omics data with multiple kernels. Furthermore; these significant genes and pathways discovered in the feature selection process are also analyzed. In experiments; the proposed method outperforms other state-of-the-art methods and has abundant biological interpretations.

Disease Gene Prediction by Integrating PPI Networks, Clinical RNA-Seq Data and OMIM Data

Disease gene prediction is a challenging task that has a variety of applications such as early diagnosis and drug development. The existing machine learning methods suffer from the imbalanced sample issue because the number of known disease genes (positive samples) is much less than that of unknown genes which are typically considered to be negative samples. In addition, most methods have not utilized clinical data from patients with a specific disease to predict disease genes. In this study, we propose a disease gene prediction algorithm (called dgSeq) by combining protein-protein interaction (PPI) network, clinical RNA-Seq data, and Online Mendelian Inheritance in Man (OMIN) data. Our dgSeq constructs differential networks based on rewiring information calculated from clinical RNA-Seq data. To select balanced sets of non-disease genes (negative samples), a disease-gene network is also constructed from OMIM data. After features are extracted from the PPI networks and differential networks, the logistic regression classifiers are trained. Our dgSeq obtains AUC values of 0.88, 0.83, and 0.80 for identifying breast cancer genes, thyroid cancer genes, and Alzheimer's disease genes, respectively, which indicates its superiority to other three competing methods. Both gene set enrichment analysis and predicted results demonstrate that dgSeq can effectively predict new disease genes.

Crosstalk between ERα and Receptor Tyrosine Kinase Signalling and Implications for the Development of Anti-Endocrine Resistance

Although anti-endocrine therapies have significantly advanced the treatment of breast cancer, they pose the problem of acquired drug resistance. The oestrogen receptor (ER)-expressing breast cancer cell lines MCF-7 and T47D alongside their in vitro derived resistant counterparts MCF-7-TR (tamoxifen-resistant) and T47D-FR (fulvestrant-resistant) showed dual resistance to fulvestrant and tamoxifen in the presence of upregulated HER1 and HER2 growth factor receptors. Our study demonstrated that tamoxifen resistance and fulvestrant resistance are associated with collateral sensitivity to the tyrosine kinase inhibitors (TKIs) lapatinib (p < 0.0001) and afatinib (p < 0.0001). Further, we found that over time, the TKIs reactivated ER&alpha; protein and/or mRNA in tamoxifen- and fulvestrant-resistant cells. Combinations of anti-endocrine agents with afatinib gave rise to significantly enhanced levels of apoptosis in both T47D-FR and MCF-7-TR in a synergistic manner versus additive effects of agents used singly. This was associated with p27^kip1 induction for anti-endocrine-resistant cells versus parental cells. Our data supports the use of combination treatment utilising dual HER1/2 inhibitors in breast cancer patients showing resistance to multiple anti-endocrine agents.

The mediator complex in genomic and non-genomic signaling in cancer

Mediator is a conserved, multi-subunit macromolecular machine divided structurally into head, middle, and tail modules, along with a transiently associating kinase module. Mediator functions as an integrator of transcriptional regulatory activity by interacting with DNA-bound transcription factors and with RNA polymerase II (Pol II) to both activate and repress gene expression. Mediator has been shown to affect multiple steps in transcription, including chromatin looping between enhancers and promoters, pre-initiation complex formation, transcriptional elongation, and mRNA splicing. Individual Mediator subunits participate in regulation of gene expression by the estrogen and androgen receptors and are altered in a number of endocrine cancers, including breast and prostate cancer. In addition to its role in genomic signaling, MED12 has been implicated in non-genomic signaling by interacting with and activating TGF-beta receptor 2 in the cytoplasm. Recent structural studies have revealed extensive inter-domain interactions and complex architecture of the Mediator-Pol II complex, suggesting that Mediator is capable of reorganizing its conformation and composition to fit cellular needs. We propose that alterations in Mediator subunit expression that occur in various cancers could impact the organization and function of Mediator, resulting in changes in gene expression that promote malignancy. A better understanding of the role of Mediator in cancer could reveal new approaches to the diagnosis and treatment of Mediator-dependent endocrine cancers, especially in settings of therapy resistance.

Copy number profiling of oncogenes in ductal carcinoma in situ of the male breast

Characterizing male breast cancer (BC) and unraveling male breast carcinogenesis is challenging because of the rarity of this disease. We investigated copy number status of 22 BC-related genes in 18 cases of pure ductal carcinoma in situ (DCIS) and in 49 cases of invasive carcinoma (IC) with adjacent DCIS (DCIS-AIC) in males using multiplex ligation-dependent probe amplification (MLPA). Results were compared to female BC and correlated with survival. Overall, copy number ratio and aberration frequency including all 22 genes showed no significant difference between the 3 groups. Individual unpaired analysis revealed a significantly higher MTDH copy number ratio in IC compared to DCIS-AIC and pure DCIS (P = 0.009 and P = 0.038, respectively). ADAM9 showed a significantly lower copy number aberration frequency in male BC, compared to female BC (P = 0.020). In DCIS-AIC, MTDH, CPD, CDC6 and TOP2A showed a lower frequency of copy number increase in males compared to females (P < 0.001 for all 4 genes). In IC, CPD gain and CCNE1 gain were independent predictors of poor overall survival. In conclusion, male DCIS and IC showed a similar copy number profile for 21 out of 22 interrogated BC-related genes, illustrating their clonal relation and the genetically advanced state of male DCIS. MTDH showed a higher copy number ratio in IC compared to adjacent and pure DCIS and may therefore play a role in male breast carcinogenesis. Differences were detected between male and female DCIS for 4 genes pointing to differences in breast carcinogenesis between the sexes.

Receptor tyrosine kinases (RTKs) in breast cancer: signaling, therapeutic implications and challenges

Breast cancer is a multifactorial disease and driven by aberrant regulation of cell signaling pathways due to the acquisition of genetic and epigenetic changes. An array of growth factors and their receptors is involved in cancer development and metastasis. Receptor Tyrosine Kinases (RTKs) constitute a class of receptors that play important role in cancer progression. RTKs are cell surface receptors with specialized structural and biological features which respond to environmental cues by initiating appropriate signaling cascades in tumor cells. RTKs are known to regulate various downstream signaling pathways such as MAPK, PI3K/Akt and JAK/STAT. These pathways have a pivotal role in the regulation of cancer stemness, angiogenesis and metastasis. These pathways are also imperative for a reciprocal interaction of tumor and stromal cells. Multi-faceted role of RTKs renders them amenable to therapy in breast cancer. However, structural mutations, gene amplification and alternate pathway activation pose challenges to anti-RTK therapy.

miR-125a-3p inhibits ERα transactivation and overrides tamoxifen resistance by targeting CDK3 in estrogen receptor-positive breast cancer

Tamoxifen (TAM) is a major adjuvant therapy for patients who are diagnosed with estrogen receptor-α (ER)-positive breast cancer; however, TAM resistance occurs often during treatment and the underlying mechanism is unclear. Here, we report that miR-125a-3p inhibits ERα transcriptional activity and, thus, ER+ breast cancer cell proliferation, which causes cell-cycle arrest at the G1/S stage, inducing apoptosis and suppressing tumor growth by targeting cyclin-dependent kinase 3 (CDK3) in vitro and in vivo. In addition, CDK3 and miR-125a-3p expression levels were measured in 37 cancerous tissues paired with noncancerous samples, and their expression levels were negatively associated with miR-125a-3p level. Of interest, miR-125a-3p level is down-regulated in MCF-7 TAM-resistant (TamR) cells. Of more importance, up-regulation of miR-125a-3p resensitizes MCF-7 TamR cells to TAM, which is dependent on CDK3 expression. These results suggest that miR-125a-3p can function as a novel tumor suppressor in ER+ breast cancer by targeting CDK3, which may be a potential therapeutic approach for TamR breast cancer therapy.-Zheng, L., Meng, X., Li, X., Zhang, Y., Li, C., Xiang, C., Xing, Y., Xia, Y., Xi, T. miR-125a-3p inhibits ERα transactivation and overrides tamoxifen resistance by targeting CDK3 in estrogen receptor-positive breast cancer.

HER2-Driven Breast Tumorigenesis Relies upon Interactions of the Estrogen Receptor with Coactivator MED1

Studies of the estrogen receptor (ER) coactivator protein Mediator subunit 1 (MED1) have revealed its specific roles in pubertal mammary gland development and potential contributions to breast tumorigenesis, based on coamplification of MED1 and HER2 in certain breast cancers. In this study, we generated a mouse model of mammary tumorigenesis harboring the MMTV-HER2 oncogene and mutation of MED1 to evaluate its role in HER2-driven tumorigenesis. MED1 mutation in its ER-interacting LxxLL motifs was sufficient to delay tumor onset and to impair tumor growth, metastasis, and cancer stem-like cell formation in this model. Mechanistic investigations revealed that MED1 acted directly to regulate ER signaling through the downstream IGF1 pathway but not the AREG pathway. Our findings show that MED1 is critical for HER2-driven breast tumorigenesis, suggesting its candidacy as a disease-selective therapeutic target.Significance: These findings identify an estrogen receptor-binding protein as a critical mediator of HER2-driven breast tumorigenesis, suggesting its candidacy as a disease-selective therapeutic target. Cancer Res; 78(2); 422-35. ©2017 AACR.

Reconstructing cancer drug response networks using multitask learning

BACKGROUND

Translating in vitro results to clinical tests is a major challenge in systems biology. Here we present a new Multi-Task learning framework which integrates thousands of cell line expression experiments to reconstruct drug specific response networks in cancer.

RESULTS

The reconstructed networks correctly identify several shared key proteins and pathways while simultaneously highlighting many cell type specific proteins. We used top proteins from each drug network to predict survival for patients prescribed the drug.

CONCLUSIONS

Predictions based on proteins from the in-vitro derived networks significantly outperformed predictions based on known cancer genes indicating that Multi-Task learning can indeed identify accurate drug response networks.

Treatment for the endocrine resistant breast cancer: Current options and future perspectives

Endocrine resistance remains a challenge and an unmet need for managing hormone receptor-positive breast cancer. The mechanisms of endocrine resistance are multifaceted and are likely to evolve over time following various single or combination therapies. The purpose of this review article is to provide general understanding of molecular basis of endocrine resistance of breast cancer and to offer comprehensive review on current treatment options and potential new treatment strategies for endocrine resistant breast cancers. Last but not the least, we discuss current challenges and future directions for management of endocrine resistant breast cancers.

Long-term remission of hormone receptor-positive/HER2-positive metastatic breast cancer due to combined treatment with everolimus/trastuzumab/exemestane: A case report

The present case report describes a postmenopausal patient with hormone receptor (HR)⁺/human epidermal growth factor receptor 2 (HER2)⁺ metastatic breast cancer, who experienced progression of disease in bilateral lungs, lymph nodes and the liver under previous endocrine therapy and trastuzumab. Following the failure of two lines of endocrine-based treatment, the patient was administered the combined treatment of everolimus, trastuzumab and exemestane following surgical resection of the liver metastasis. A durable partial remission was achieved, which has continued for >27 months. This prominent clinical outcome in this patient demonstrates that the combined administration of endocrine therapy, trastuzumab and everolimus is clinically effective, and may induce long-term remission in patients with HR⁺/HER2⁺ metastatic breast cancer.

Mediator Complex Subunit MED1 Protein Expression Is Decreased during Bladder Cancer Progression

Introduction

Bladder cancer (BCa) is among the most frequent cancer entities and relevantly contributes to cancer-associated deaths worldwide. The multi-protein Mediator complex is a central regulator of the transcriptional machinery of protein-coding genes and has been described to be altered in several malignancies. MED1, a subunit of the tail module, was described to negatively modulate expression of metastasis-related genes and to be downregulated in melanoma and lung cancer. In contrast, MED1 hyperactivity was described in breast and prostate cancer, likely due its function as a hub for nuclear hormone receptors. So far, only little is known about the function of the Mediator complex in BCa. The aim of this study was therefore to investigate the role of MED1 in BCa as a prognostic biomarker and a biomarker of disease progression.

Methods

The protein expression of MED1 was assessed by immunohistochemistry (IHC) on tissue microarrays from 224 patients: benign urothelium n = 31, non-muscle invasive BCa (pTis, pT1) n = 72, and muscle invasive BCa (pT2–T4) n = 121. Comprehensive clinicopathological information including follow-up were available. Quantification of MED1 protein expression was evaluated by the semiquantitative image analysis program Definiens.

Results

MED1 expression significantly decreased during BCa progression from benign urothelium to advanced BCa. Muscle invasion, the crucial step in BCa progression, was associated with low MED1 protein expression. Accordingly, decreased MED1 expression was found in primary BCa samples with positive lymphonodal status and distant metastases. Furthermore, cancer-specific survival was significantly worse in the group of low MED1 expression.

Conclusion

Our findings show that the downregulation of MED1 is associated with muscle invasion, metastatic spread, and shorter overall survival in BCa.

MED1 may explain the interaction between receptor tyrosine kinases and ERα66 in the complicated network of Tamoxifen resistance

According to the American Society of Clinical Oncology or ASCO's clinical practice guidelines, administration of Tamoxifen for hormone receptor positive patients improved outcomes. However, many studies have been conducted in this issue, with the rise of Tamoxifen resistance in recent decades. There are many alternative growth cascades that are activated in Tamoxifen resistant cells. The most common and well characterized components of such a resistant network are receptor tyrosine kinases, or RTKs, which can influence many other cellular processes. The interactions between estrogen dependent and independent pathways further complicate the networking. MED1, as a member of a mediator complex, which is activated by RTK growth pathways, plays role in co-activating ERα66 to transcribe genes and enhance cellular proliferation. Herein, we will discuss MED1, a novel biomarker which can explain how RTKs interact with ERα66 which results in Tamoxifen resistance.