MYC-Driven Pathways in Breast Cancer Subtypes

Non-genetic heterogeneity and immune subtyping in breast cancer: Implications for immunotherapy and targeted therapeutics

Breast cancer (BC) is a complex and multifactorial disease, driven by genetic alterations that promote tumor growth and progression. However, recent research has highlighted the importance of non-genetic factors in shaping cancer evolution and influencing therapeutic outcomes. Non-genetic heterogeneity refers to diverse subpopulations of cancer cells within breast tumors, exhibiting distinct phenotypic and functional properties. These subpopulations can arise through various mechanisms, including clonal evolution, genetic changes, epigenetic changes, and reversible phenotypic transitions. Although genetic and epigenetic changes are important points of the pathology of breast cancer yet, the immune system also plays a crucial role in its progression. In clinical management, histologic and molecular classification of BC are used. Immunological subtyping of BC has gained attention in recent years as compared to traditional techniques. Intratumoral heterogeneity revealed by immunological microenvironment (IME) has opened novel opportunities for immunotherapy research. This systematic review is focused on non-genetic variability to identify and interlink immunological subgroups in breast cancer. This review provides a deep understanding of adaptive methods adopted by tumor cells to withstand changes in the tumor microenvironment and selective pressure imposed by medications. These adaptive methods include alterations in drug targets, immune system evasion, activation of survival pathways, and alterations in metabolism. Understanding non-genetic heterogeneity is essential for the development of targeted therapies.

Mechanisms of sensitivity and resistance to CDK4/CDK6 inhibitors in hormone receptor-positive breast cancer treatment

Cell cycle dysregulation is a hallmark of cancer that promotes eccessive cell division. Cyclin-dependent kinase 4 (CDK4) and cyclin-dependent kinase 6 (CDK6) are key molecules in the G1-to-S phase cell cycle transition and are crucial for the onset, survival, and progression of breast cancer (BC). Small-molecule CDK4/CDK6 inhibitors (CDK4/6i) block phosphorylation of tumor suppressor Rb and thus restrain susceptible BC cells in G1 phase. Three CDK4/6i are approved for the first-line treatment of patients with advanced/metastatic hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) BC in combination with endocrine therapy (ET). Though this has improved the clinical outcomes for survival of BC patients, there is no established standard next-line treatment to tackle drug resistance. Recent studies suggest that CDK4/6i can modulate other distinct effects in both BC and breast stromal compartments, which may provide new insights into aspects of their clinical activity. This review describes the biochemistry of the CDK4/6-Rb-E2F pathway in HR+ BC, then discusses how CDK4/6i can trigger other effects in BC/breast stromal compartments, and finally outlines the mechanisms of CDK4/6i resistance that have emerged in recent preclinical studies and clinical cohorts, emphasizing the impact of these findings on novel therapeutic opportunities in BC.

GAS5 lncRNA: A biomarker and therapeutic target in breast cancer

Breast cancer is one of the most common causes of cancer-related mortality globally, and its aggressive phenotype results in poor treatment outcomes. Growth Arrest-Specific 5 long non-coding RNA has attracted considerable attention due to its pivotal function in apoptosis regulation and tumor aggressiveness in breast cancer. Gas5 enhances apoptosis by regulating apoptotic proteins, such as caspases and BCL2 family proteins, and the sensitivity of BCCs to chemotherapeutic agents. At the same time, low levels of GAS5 increased invasion, metastasis, and overall tumor aggressiveness. GAS5 also regulates EMT markers, critical for cancer metastasis, and influences tumor cell proliferation by regulating various signaling components. As a result, GAS5 can be restored to suppress tumor development as a possible therapeutic strategy, which might present promising prospects for a patient's treatment. Its activity levels might also be a crucial indicator and diagnostic parameter for prediction. This review highlights the significant role of GAS5 in modulating apoptosis and tumor aggressiveness in breast cancer, emphasizing its potential as a therapeutic target for breast cancer treatment and management.

Toxoplasma gondii suppresses proliferation and migration of breast cancer cells by regulating their transcriptome

BACKGROUND

Breast cancer is the most common cancer in women worldwide. Toxoplasma gondii (T. gondii) has shown anticancer activity in breast cancer mouse models, and exerted beneficial effect on the survival of breast cancer patients, but the mechanism was unclear.

METHODS

The effect of tachyzoites of T. gondii (RH and ME49 strains) on human breast cancer cells (MCF-7 and MDA-MB-231 cells) proliferation and migration was assessed using cell growth curve and wound healing assays. Dual RNA-seq was performed for T. gondii-infected and non-infected cells to determine the differentially expressed genes (DEGs). Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Protein-Protein Interaction Networks analysis (PPI) were performed to explore the related signaling pathway and hub genes. Hub genes were validated using the Kaplan-Meier plotter database, and Pathogen Host Interaction (PHI-base) database. The results were verified by qRT-PCR.

RESULTS

The tachyzoites of T. gondii decreased the expression of Ki67 and increased the expression of E-cadherin, resulting in suppressing the proliferation and migration of infected human breast cancer cells. The inhibitory effect of T. gondii on breast cancer cells showed a significant dose-response relationship. Compared with the control group, 2321 genes were transcriptionally regulated in MCF-7 cells infected with T. gondii, while 169 genes were transcriptionally regulated in infected MDA-MB-231 cells. Among these genes, 698 genes in infected MCF-7 cells and 67 genes in infected MDA-MB-231 cells were validated by the publicly available database. GO and KEGG analyses suggested that several pathways were involved in anticancer function of T. gondii, such as ribosome, interleukin-17 signaling, coronavirus disease pathway, and breast cancer pathway. BRCA1, MYC and IL-6 were identified as the top three hub genes in infected-breast cancer cells based on the connectivity of PPI analysis. In addition, after interacting with breast cancer cells, the expression of ROP16 and ROP18 in T. gondii increased, while the expression of crt, TgIST, GRA15, GRA24 and MIC13 decreased.

CONCLUSIONS

T. gondii transcriptionally regulates several signaling pathways by altering the hub genes such as BRCA1, MYC and IL-6, which can inhibit the breast tumor growth and migration, hinting at a potential therapeutic strategy.

Potential of the nanoplatform and PROTAC interface to achieve targeted protein degradation through the Ubiquitin-Proteasome system

In eukaryotic cells, the ubiquitin-proteasome system (UPS) plays a crucial role in selectively breaking down specific proteins. The ability of the UPS to target proteins effectively and expedite their removal has significantly contributed to the evolution of UPS-based targeted protein degradation (TPD) strategies. In particular, proteolysis targeting chimeras (PROTACs) are an immensely promising tool due to their high efficiency, extensive target range, and negligible drug resistance. This breakthrough has overcome the limitations posed by traditionally "non-druggable" proteins. However, their high molecular weight and constrained solubility impede the delivery of PROTACs. Fortunately, the field of nanomedicine has experienced significant growth, enabling the delivery of PROTACs through nanoscale drug-delivery systems, which effectively improves the stability, solubility, drug distribution, tissue-specific accumulation, and stimulus-responsive release of PROTACs. This article reviews the mechanism of action attributed to PROTACs and their potential implications for clinical applications. Moreover, we present strategies involving nanoplatforms for the effective delivery of PROTACs and evaluate recent advances in targeting nanoplatforms to the UPS. Ultimately, an assessment is conducted to determine the feasibility of utilizing PROTACs and nanoplatforms for UPS-based TPD. The primary aim of this review is to provide innovative, reliable solutions to overcome the current challenges obstructing the effective use of PROTACs in the management of cancer, neurodegenerative diseases, and metabolic syndrome. Therefore, this is a promising technology for improving the treatment status of major diseases.

Characterization of MYBL1 Gene in Triple-Negative Breast Cancers and the Genes' Relationship to Alterations Identified at the Chromosome 8q Loci

The MYBL1 gene is a strong transcriptional activator involved in events associated with cancer progression. Previous data show MYBL1 overexpressed in triple-negative breast cancer (TNBC). There are two parts to this study related to further characterizing the MYBL1 gene. We start by characterizing MYBL1 reference sequence variants and isoforms. The results of this study will help in future experiments in the event there is a need to characterize functional variants and isoforms of the gene. In part two, we identify and validate expression and gene-related alterations of MYBL1, VCIP1, MYC and BOP1 genes in TNBC cell lines and patient samples selected from the Breast Invasive Carcinoma TCGA 2015 dataset available at cBioPortal.org. The four genes are located at chromosomal regions 8q13.1 to 8q.24.3 loci, regions previously identified as demonstrating a high percentage of alterations in breast cancer. We identify alterations, including changes in expression, deletions, amplifications and fusions in MYBL1, VCPIP1, BOP1 and MYC genes in many of the same patients, suggesting the panel of genes is involved in coordinated activity in patients. We propose that MYBL1, VCPIP1, MYC and BOP1 collectively be considered as genes associated with the chromosome 8q loci that potentially play a role in TNBC pathogenesis.

CRISPR-Cas9 technology: As an efficient genome modification tool in the cancer diagnosis and treatment

Cancer is the second most common cause of death globally and is a major public health concern. Managing this disease is difficult due to its multiple stages and numerous genetic and epigenetic changes. Traditional cancer diagnosis and treatment methods have limitations, making it crucial to develop new modalities to combat the increasing burden of cancer. The clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) system has transformed genetic engineering due to its simplicity, specificity, low cytotoxicity, and cost-effectiveness. It has been proposed as an effective technology to enhance cancer diagnosis and treatment strategies. This article presents the most recent discoveries regarding the structure, mechanism, and delivery methods of the highly powerful genome editing tool, CRISPR-Cas9. In terms of diagnosis, the article examines the role of CRISPR-Cas9 in detecting microRNAs and DNA methylation, and discusses two popular gene detection techniques that utilize the CRISPR-Cas system: DNA endonuclease-targeted CRISPR trans reporter and specific high sensitivity enzymatic reporter unlocking. Regarding treatment, the article explores several genes that have been identified and modified by CRISPR-Cas9 for effective tumorigenesis of common cancers such as breast, lung, and colorectal cancer. The present review also addresses the challenges and ethical issues associated with using CRISPR-Cas9 as a diagnostic and therapeutic tool. Despite some limitations, CRISPR-Cas9-based cancer diagnosis has the potential to become the next generation of cancer diagnostic tools, and the continuous progress of CRISPR-Cas9 can greatly aid in cancer treatment.

Hepatitis C virus may accelerate breast cancer progression by increasing mutant p53 and c-Myc oncoproteins circulating levels

BACKGROUND

Hepatitis C virus (HCV) was reported to relate to polymorphous and frequent extrahepatic manifestation. Despite the limited studies, HCV viral oncoproteins may be implicated in breast cancer (BC) tumor aggressiveness. In a trial to elucidate a mechanistic link, this study aimed to investigate a mutant p53 and c-Myc oncoprotein expression levels in BC patients with and without HCV infection.

METHODS

A total of 215 BC patients (119 infected and 96 non-infected with HCV) were collected. ELISA was used for detection of anti-HCV antibodies, mutant p53, c-Myc, HCV-NS4, CEA, CA 125, and CA-15.3.

RESULTS

HCV infection was related to BC late stages, lymph-node invasion, distant metastasis, high grades, and large size. HCV-infected patients had a significantly (P < 0.05) higher WBCs, ALT and AST activity, bilirubin CEA, CA125 and CA15.3 levels, and reduced hemoglobin, albumin, and RBCs count. Regardless of tumor severity, HCV infection was associated with significant elevated levels of mutant p53 (22.5 ± 3.5 µg/mL; 1.9-fold increase) and c-Myc (21.4 ± 1.8 µg/mL; 1.5-fold increase). Among HCV-infected patients, elevated levels of p53 and c-Myc were significantly correlated with elevated tumor markers (CEA, CA 125, and CA15.3) and HCV-NS4 levels.

CONCLUSIONS

This study concluded that HCV infection may be accompanied with BC severity behavior and this may be owing to elevated expression of mutant p53 and c-Myc oncoproteins.

Combinational therapy with Myc decoy oligodeoxynucleotides encapsulated in nanocarrier and X-irradiation on breast cancer cells

The Myc gene is the essential oncogene in triple-negative breast cancer (TNBC). This study investigates the synergistic effects of combining Myc decoy oligodeoxynucleotides-encapsulated niosomes-selenium hybrid nanocarriers with X-irradiation exposure on the MDA-MB-468 cell line. Decoy and scramble ODNs for Myc transcription factor were designed and synthesized based on promoter sequences of the Bcl2 gene. The nanocarriers were synthesized by loading Myc ODNs and selenium into chitosan (Chi-Se-DEC), which was then encapsulated in niosome-nanocarriers (NISM@Chi-Se-DEC). FT-IR, DLS, FESEM, and hemolysis tests were applied to confirm its characterization and physicochemical properties. Moreover, cellular uptake, cellular toxicity, apoptosis, cell cycle, and scratch repair assays were performed to evaluate its anticancer effects on cancer cells. All anticancer assessments were repeated under X-ray irradiation conditions (fractionated 2Gy). Physicochemical characteristics of niosomes containing SeNPs and ODNs showed that it is synthesized appropriately. It revealed that the anticancer effect of NISM@Chi-Se-DEC can be significantly improved in combination with X-ray irradiation treatment. It can be concluded that NISM@Chi-Se-DEC nanocarriers have the potential as a therapeutic agent for cancer treatment, particularly in combination with radiation therapy and in-vivo experiments are necessary to confirm the efficacy of this nano-drug.

MYC is a clinically significant driver of mTOR inhibitor resistance in breast cancer

Targeting the PI3K-AKT-mTOR pathway is a promising therapeutic strategy for breast cancer treatment. However, low response rates and development of resistance to PI3K-AKT-mTOR inhibitors remain major clinical challenges. Here, we show that MYC activation drives resistance to mTOR inhibitors (mTORi) in breast cancer. Multiomic profiling of mouse invasive lobular carcinoma (ILC) tumors revealed recurrent Myc amplifications in tumors that acquired resistance to the mTORi AZD8055. MYC activation was associated with biological processes linked to mTORi response and counteracted mTORi-induced translation inhibition by promoting translation of ribosomal proteins. In vitro and in vivo induction of MYC conferred mTORi resistance in mouse and human breast cancer models. Conversely, AZD8055-resistant ILC cells depended on MYC, as demonstrated by the synergistic effects of mTORi and MYCi combination treatment. Notably, MYC status was significantly associated with poor response to everolimus therapy in metastatic breast cancer patients. Thus, MYC is a clinically relevant driver of mTORi resistance that may stratify breast cancer patients for mTOR-targeted therapies.

MicroRNA regulation of the serine synthesis pathway in endocrine-resistant breast cancer cells

Despite the successful combination of therapies improving survival of estrogen receptor α (ER+) breast cancer patients with metastatic disease, mechanisms for acquired endocrine resistance remain to be fully elucidated. The RNA binding protein HNRNPA2B1 (A2B1), a reader of N(6)-methyladenosine (m6A) in transcribed RNA, is upregulated in endocrine-resistant, ER+ LCC9 and LY2 cells compared to parental MCF-7 endocrine-sensitive luminal A breast cancer cells. The miRNA-seq transcriptome of MCF-7 cells overexpressing A2B1 identified the serine metabolic processes pathway. Increased expression of two key enzymes in the serine synthesis pathway (SSP), phosphoserine aminotransferase 1 (PSAT1) and phosphoglycerate dehydrogenase (PHGDH), correlates with poor outcomes in ER+ breast patients who received tamoxifen (TAM). We reported that PSAT1 and PHGDH were higher in LCC9 and LY2 cells compared to MCF-7 cells and their knockdown enhanced TAM sensitivity in these-resistant cells. Here we demonstrate that stable, modest overexpression of A2B1 in MCF-7 cells increased PSAT1 and PHGDH and endocrine resistance. We identified four miRNAs downregulated in MCF-7-A2B1 cells that directly target the PSAT1 3'UTR (miR-145-5p and miR-424-5p), and the PHGDH 3'UTR (miR-34b-5p and miR-876-5p) in dual luciferase assays. Lower expression of miR-145-5p and miR-424-5p in LCC9 and ZR-75-1-4-OHT cells correlated with increased PSAT1 and lower expression of miR-34b-5p and miR-876-5p in LCC9 and ZR-75-1-4-OHT cells correlated with increased PHGDH. Transient transfection of these miRNAs restored endocrine-therapy sensitivity in LCC9 and ZR-75-1-4-OHT cells. Overall, our data suggest a role for decreased A2B1-regulated miRNAs in endocrine resistance and upregulation of the SSP to promote tumor progression in ER+ breast cancer.

Alignment of spatial genomics data using deep Gaussian processes

Spatially resolved genomic technologies have allowed us to study the physical organization of cells and tissues, and promise an understanding of local interactions between cells. However, it remains difficult to precisely align spatial observations across slices, samples, scales, individuals and technologies. Here, we propose a probabilistic model that aligns spatially-resolved samples onto a known or unknown common coordinate system (CCS) with respect to phenotypic readouts (for example, gene expression). Our method, Gaussian Process Spatial Alignment (GPSA), consists of a two-layer Gaussian process: the first layer maps observed samples' spatial locations onto a CCS, and the second layer maps from the CCS to the observed readouts. Our approach enables complex downstream spatially aware analyses that are impossible or inaccurate with unaligned data, including an analysis of variance, creation of a dense three-dimensional (3D) atlas from sparse two-dimensional (2D) slices or association tests across data modalities.

Modes of Action of a Novel c-MYC Inhibiting 1,2,4-Oxadiazole Derivative in Leukemia and Breast Cancer Cells

The c-MYC oncogene regulates multiple cellular activities and is a potent driver of many highly aggressive human cancers, such as leukemia and triple-negative breast cancer. The oxadiazole class of compounds has gained increasing interest for its anticancer activities. The aim of this study was to investigate the molecular modes of action of a 1,2,4-oxadiazole derivative (ZINC15675948) as a c-MYC inhibitor. ZINC15675948 displayed profound cytotoxicity at the nanomolar range in CCRF-CEM leukemia and MDA-MB-231-pcDNA3 breast cancer cells. Multidrug-resistant sublines thereof (i.e., CEM/ADR5000 and MDA-MB-231-BCRP) were moderately cross-resistant to this compound (<10-fold). Molecular docking and microscale thermophoresis revealed a strong binding of ZINC15675948 to c-MYC by interacting close to the c-MYC/MAX interface. A c-MYC reporter assay demonstrated that ZINC15675948 inhibited c-MYC activity. Western blotting and qRT-PCR showed that c-MYC expression was downregulated by ZINC15675948. Applying microarray hybridization and signaling pathway analyses, ZINC15675948 affected signaling routes downstream of c-MYC in both leukemia and breast cancer cells as demonstrated by the induction of DNA damage using single cell gel electrophoresis (alkaline comet assay) and induction of apoptosis using flow cytometry. ZINC15675948 also caused G2/M phase and S phase arrest in CCRF-CEM cells and MDA-MB-231-pcDNA3 cells, respectively, accompanied by the downregulation of CDK1 and p-CDK2 expression using western blotting. Autophagy induction was observed in CCRF-CEM cells but not MDA-MB-231-pcDNA3 cells. Furthermore, microarray-based mRNA expression profiling indicated that ZINC15675948 may target c-MYC-regulated ubiquitination, since the novel ubiquitin ligase (ELL2) was upregulated in the absence of c-MYC expression. We propose that ZINC15675948 is a promising natural product-derived compound targeting c-MYC in c-MYC-driven cancers through DNA damage, cell cycle arrest, and apoptosis.

Parabens Promote Protumorigenic Effects in Luminal Breast Cancer Cell Lines With Diverse Genetic Ancestry

Context

One in 8 women will develop breast cancer in their lifetime. Yet, the burden of disease is greater in Black women. Black women have a 40% higher mortality rate than White women, and a higher incidence of breast cancer at age 40 and younger. While the underlying cause of this disparity is multifactorial, exposure to endocrine disrupting chemicals (EDCs) in hair and other personal care products has been associated with an increased risk of breast cancer. Parabens are known EDCs that are commonly used as preservatives in hair and other personal care products, and Black women are disproportionately exposed to products containing parabens.

Objective

Studies have shown that parabens impact breast cancer cell proliferation, death, migration/invasion, and metabolism, as well as gene expression in vitro. However, these studies were conducted using cell lines of European ancestry; to date, no studies have utilized breast cancer cell lines of West African ancestry to examine the effects of parabens on breast cancer progression. Like breast cancer cell lines with European ancestry, we hypothesize that parabens promote protumorigenic effects in breast cancer cell lines of West African ancestry.

Methods

Luminal breast cancer cell lines with West African ancestry (HCC1500) and European ancestry (MCF-7) were treated with biologically relevant doses of methylparaben, propylparaben, and butylparaben.

Results

Following treatment, estrogen receptor target gene expression and cell viability were examined. We observed altered estrogen receptor target gene expression and cell viability that was paraben and cell line specific.

Conclusion

This study provides greater insight into the tumorigenic role of parabens in the progression of breast cancer in Black women.

The effects of MYC on exosomes derived from cancer cells in the context of breast cancer

MYC amplification and overexpression in breast cancer occur 16% and 22%, respectively, and MYC has a linchpin role in breast carcinogenesis. Emerging evidence has started to shed light on central role of MYC in breast cancer progression. On the contrary, tumor-derived exosomes and their cargo molecules are required for the modulation of the tumor environment and to promote carcinogenesis. Still, how MYC regulates tumor-derived exosomes is still a matter of investigation in the context of breast cancer. Here, we investigated for the first time how MYC affects the biological functions of normal breast cells cocultured with exosomes derived from MYC-expression manipulated breast cancer cells. Accordingly, exosomes were isolated from MCF-7 and MDA-MB-231 cells that MYC expression was manipulated through siRNAs or lentiviral vectors by using exosome isolation reagent. Then, normal breast epithelial MCF-10A cells were treated with breast cancer cell-derived exosomes. The cellular activity of MCF-10A was investigated by cell growth assay, wound healing assay, and transwell assay. Our results suggested that MCF-10A cells treated with exosomes derived from MYC-overexpressing breast cancer cells demonstrated higher proliferation and migration capability compared with nontreated cells. Likewise, MCF-10A cells treated with exosomes derived from MYC-silenced cancer cells did not show high proliferation and invasive capacity. Overall, MYC can drive the functions of exosomes secreted from breast cancer cells. This may allow exploring a new mechanism how tumor cells regulate cancer progression and modulate tumor environment. The present study clears the way for further researches as in vivo studies and multi-omics that clarify exosomal content in an MYC-dependent manner.

Role of Glucose Metabolic Reprogramming in Breast Cancer Progression and Drug Resistance

The involvement of glucose metabolic reprogramming in breast cancer progression, metastasis, and therapy resistance has been increasingly appreciated. Studies in recent years have revealed molecular mechanisms by which glucose metabolic reprogramming regulates breast cancer. To date, despite a few metabolism-based drugs being tested in or en route to clinical trials, no drugs targeting glucose metabolism pathways have yet been approved to treat breast cancer. Here, we review the roles and mechanisms of action of glucose metabolic reprogramming in breast cancer progression and drug resistance. In addition, we summarize the currently available metabolic inhibitors targeting glucose metabolism and discuss the challenges and opportunities in targeting this pathway for breast cancer treatment.

Next-Generation Sequencing and Triple-Negative Breast Cancer: Insights and Applications

The poor survival of triple-negative breast cancer (TNBC) is due to its aggressive behavior, large heterogeneity, and high risk of recurrence. A comprehensive molecular investigation of this type of breast cancer using high-throughput next-generation sequencing (NGS) methods may help to elucidate its potential progression and discover biomarkers related to patient survival. In this review, the NGS applications in TNBC research are described. Many NGS studies point to TP53 mutations, immunocheckpoint response genes, and aberrations in the PIK3CA and DNA repair pathways as recurrent pathogenic alterations in TNBC. Beyond their diagnostic and predictive/prognostic value, these findings suggest potential personalized treatments in PD -L1-positive TNBC or in TNBC with a homologous recombination deficit. Moreover, the comprehensive sequencing of large genomes with NGS has enabled the identification of novel markers with clinical value in TNBC, such as AURKA, MYC, and JARID2 mutations. In addition, NGS investigations to explore ethnicity-specific alterations have pointed to EZH2 overexpression, BRCA1 alterations, and a BRCA2-delaAAGA mutation as possible molecular signatures of African and African American TNBC. Finally, the development of long-read sequencing methods and their combination with optimized short-read techniques promise to improve the efficiency of NGS approaches for future massive clinical use.

Non-fused imidazole-biphenyl analogs repress triple-negative breast cancer growth by mainly stabilizing the c-MYC G-quadruplex via a multi-site binding mode

As oncogene c-MYC is abnormally expressed during TNBC pathogenesis, stabilizing its promoter G-quadruplex (G4), which may thus inhibit c-MYC expression and promote DNA damage, may be a potential anti-TNBC strategy. However, large quantities of potential G4-forming sites exist in the human genome, which represents a potential drug selectivity problem. In order to achieve better recognition for c-MYC G4, we herein presented a new approach of designing small-molecule ligands by linking tandem aromatic rings with the c-MYC G4 selective binding motifs. Thus, a series of non-fused, conformation-tunable imidazole-biphenyl analogs were designed and synthesized. Among them, the optimal ligand appeared more effective on stabilizing c-MYC G4 than other types of G4s possibly through an adaptive, multi-site binding mode involved of end-stacking, groove-binding and loop-interacting. Then, the optimal ligand exerted good inhibitory activity on c-MYC expression and induced remarkable DNA damage, leading to the occurrence of G2/M phase arrest, apoptosis and autophagy. Furthermore, the optimal ligand exhibited potent antitumor effects in a TNBC xenograft tumor model. To sum up, this work offers new insights for the development of selective c-MYC G4 ligands against TNBC.

Myc derived circRNA promotes triple-negative breast cancer progression via reprogramming fatty acid metabolism

Myc is a well-known proto-oncogene that is frequently amplified and activated in breast cancer, especially in triple-negative breast cancer (TNBC). However, the role of circular RNA (circRNA) generated by Myc remains unclear. Herein, we found that circMyc (hsa_circ_0085533) was remarkably upregulated in TNBC tissues and cell lines, which was attributed to gene amplification. Genetic knockdown of circMyc mediated by lentiviral vector significantly inhibited TNBC cell proliferation and invasion. Importantly, circMyc increased cellular triglycerides, cholesterols and lipid droplet contents. CircMyc was detected in both cytoplasm and nucleus, cytoplasmic circMyc could directly bind to HuR protein, facilitating the binding of HuR to SREBP1 mRNA, resulting in increasing SREBP1 mRNA stability. Nuclear circMyc bound to Myc protein, facilitating the occupation of Myc on SREBP1 promoter, leading to increasing SREBP1 transcription. As a result, the elevated SREBP1 increased the expression of its downstream lipogenic enzymes, enhancing lipogenesis and TNBC progression. Moreover, the orthotopic xenograft model showed that depletion of circMyc markedly inhibited lipogenesis and reduced tumor size. Clinically, high circMyc was closely related to larger tumor volume, later clinical stage and lymph node metastasis, functioning as an adverse prognostic factor. Collectively, our findings characterize a novel Myc-derived circRNA controlling TNBC tumorigenesis via regulation of metabolic reprogramming, implying a promising therapeutic target.

Role of Secreted Frizzled-Related Protein 1 in Early Breast Carcinogenesis and Breast Cancer Aggressiveness

A human transcriptome array on ERα-positive breast cancer continuum of risk identified Secreted Frizzled-Related Protein 1 (SFRP1) as decreased during breast cancer progression. In addition, SFRP1 was inversely associated with breast tissue age-related lobular involution, and differentially regulated in women with regard to their parity status and the presence of microcalcifications. The causal role of SFRP1 in breast carcinogenesis remains, nevertheless, not well understood. In this study, we characterized mammary epithelial cells from both nulliparous and multiparous mice in organoid culture ex vivo, in the presence of estradiol (E2) and/or hydroxyapatite microcalcifications (HA). Furthermore, we have modulated SFRP1 expression in breast cancer cell lines, including the MCF10A series, and investigated their tumoral properties. We observed that organoids obtained from multiparous mice were resistant to E2 treatment, while organoids obtained from nulliparous mice developed the luminal phenotype associated with a lower ratio between Sfrp1 and Esr1 expression. The decrease in SFRP1 expression in MCF10A and MCF10AT1 cell lines increased their tumorigenic properties in vitro. On the other hand, the overexpression of SFRP1 in MCF10DCIS, MCF10CA1a, and MCF7 reduced their aggressiveness. Our results support the hypothesis that a lack of SFRP1 could have a causal role in early breast carcinogenesis.

A Basic Review on Estrogen Receptor Signaling Pathways in Breast Cancer

Breast cancer is the most common cancer and the deadliest among women worldwide. Estrogen signaling is closely associated with hormone-dependent breast cancer (estrogen and progesterone receptor positive), which accounts for two-thirds of tumors. Hormone therapy using antiestrogens is the gold standard, but resistance to these treatments invariably occurs through various biological mechanisms, such as changes in estrogen receptor activity, mutations in the ESR1 gene, aberrant activation of the PI3K pathway or cell cycle dysregulations. All these factors have led to the development of new therapies, such as selective estrogen receptor degraders (SERDs), or combination therapies with cyclin-dependent kinases (CDK) 4/6 or PI3K inhibitors. Therefore, understanding the estrogen pathway is essential for the treatment and new drug development of hormone-dependent cancers. This mini-review summarizes current literature on the signalization, mechanisms of action and clinical implications of estrogen receptors in breast cancer.

Metabolomic Signatures of Scarff-Bloom-Richardson (SBR) Grade in Non-Metastatic Breast Cancer

PURPOSE

Identification of metabolomic biomarkers of high SBR grade in non-metastatic breast cancer.

METHODS

This retrospective bicentric metabolomic analysis included a training set (n = 51) and a validation set (n = 49) of breast cancer tumors, all classified as high-grade (grade III) or low-grade (grade I-II). Metabolomes of tissue samples were studied by liquid chromatography coupled with mass spectrometry.

RESULTS

A molecular signature of the top 12 metabolites was identified from a database of 602 frequently predicted metabolites. Partial least squares discriminant analyses showed that accuracies were 0.81 and 0.82, the R2 scores were 0.57 and 0.55, and the Q2 scores were 0.44431 and 0.40147 for the training set and validation set, respectively; areas under the curve for the Receiver Operating Characteristic Curve were 0.882 and 0.886. The most relevant metabolite was diacetylspermine. Metabolite set enrichment analyses and metabolic pathway analyses highlighted the tryptophan metabolism pathway, but the concentration of individual metabolites varied between tumor samples.

CONCLUSIONS

This study indicates that high-grade invasive tumors are related to diacetylspermine and tryptophan metabolism, both involved in the inhibition of the immune response. Targeting these pathways could restore anti-tumor immunity and have a synergistic effect with immunotherapy. Recent studies could not demonstrate the effectiveness of this strategy, but the use of theragnostic metabolomic signatures should allow better selection of patients.

Potential predictive value of circulating tumor DNA (ctDNA) mutations for the efficacy of immune checkpoint inhibitors in advanced triple-negative breast cancer

Background: In recent years, tumor immunotherapy has become a viable treatment option for triple negative breast cancer (TNBC). Among these, immune checkpoint inhibitors (ICIs) have demonstrated good efficacy in advanced TNBC patients with programmed death-ligand 1 (PD-L1) positive expression. However, only 63% of PD-L1-positive individuals showed any benefit from ICIs. Therefore, finding new predictive biomarkers will aid in identifying patients who are likely to benefit from ICIs. In this study, we used liquid biopsies and next-generation sequencing (NGS) to dynamically detect changes in circulating tumor DNA (ctDNA) in the blood of patients with advanced TNBC treated with ICIs and focused on its potential predictive value.

Methods: From May 2018 to October 2020, patients with advanced TNBC treated with ICIs at Shandong Cancer Hospital were included prospectively. Patient blood samples were obtained at the pretreatment baseline, first response evaluation, and disease progression timepoints. Furthermore, 457 cancer-related genes were evaluated by NGS, and patients’ ctDNA mutations, gene mutation rates, and other indicators were determined and coupled with clinical data for statistical analysis.

Results: A total of 11 TNBC patients were included in this study. The overall objective response rate (ORR) was 27.3%, with a 6.1-month median progression-free survival (PFS) (95% confidence interval: 3.877–8.323 months). Of the 11 baseline blood samples, 48 mutations were found, with the most common mutation types being frame shift indels, synonymous single-nucleotide variations (SNVs), frame indel missenses, splicing, and stop gains. Additionally, univariate Cox regression analysis revealed that advanced TNBC patients with one of 12 mutant genes (CYP2D6 deletion and GNAS, BCL2L1, H3F3C, LAG3, FGF23, CCND2, SESN1, SNHG16, MYC, HLA-E, and MCL1 gain) had a shorter PFS with ICI treatment (p &lt; 0.05). To some extent, dynamic changes of ctDNA might indicate the efficacy of ICIs.

Conclusion: Our data indicate that ICI efficacy in patients with advanced TNBC may be predicted by 12 mutant ctDNA genes. Additionally, dynamic alterations in peripheral blood ctDNA might be used to track the effectiveness of ICI therapy in those with advanced TNBC.

Investigating In Situ Expression of c-MYC and Candidate Ubiquitin-Specific Proteases in DLBCL and Assessment for Peptidyl Disruptor Molecule against c-MYC-USP37 Complex

Diffuse Large B-Cell Lymphoma (DLBCL) is the most common form of non-Hodgkin's lymphoma (NHL). Elevated expression of c-MYC in DLBCL is associated with poor prognosis of the disease. In different cancers, c-MYC has been found regulated by different ubiquitin-specific proteases (USPs), but to date, the role of USPs in c-MYC regulation has not been investigated in DLBCL. In this study, in situ co expression of c-MYC and three candidates USPs, USP28, USP36 and USP37, have been investigated in both the ABC and GCB subtypes of DLBCL. This shows that USP37 expression is positively correlated with the c-MYC expression in the ABC subtype of DLBCL. Structurally, both c-MYC and USP37 has shown large proportion of intrinsically disordered regions, minimizing their chances for full structure crystallization. Peptide array and docking simulations has shown that N-terminal region of c-MYC interacts directly with residues within and in proximity of catalytically active C19 domain of the USP37. Given the structural properties of the interaction sites in the c-MYC-USP37 complex, a peptidyl inhibitor has been designed. Molecular docking has shown that the peptide fits well in the targeted site of c-MYC, masking most of its residues involved in the binding with USP37. The findings could further be exploited to develop therapeutic interventions against the ABC subtype of DLBCL.

Noncoding RNAs Controlling Oxidative Stress in Cancer

Mitochondria in cancer cells tend to overproduce reactive oxygen species (ROS), inducing a vicious cycle between mitochondria, ROS, genomic instability, and cancer development. The first part of this review deals with the role of noncoding RNAs in regulating mitochondrial ROS production and the expression of antioxidants in cancer cells, preventing the increase of ROS in the tumor microenvironment. In addition, cytotoxic T and natural killer cells release high levels of ROS, inducing cell death, while anti-immune regulatory T cells, tumor-associated M2 macrophages, and myeloid-derived suppressor cells, at least at the initial stage of tumor growth, release low levels of ROS supporting tumor growth. Therefore, this review's second part deals with noncoding RNAs' role in regulating the metabolic reprogramming of immune cells about ROS release. Furthermore, the enrichment of noncoding RNAs in microvesicles allows communication between cell types in a tumor and between a tumor and tumor-adjacent tissues. Therefore, the third part illustrates how noncoding RNA-containing microvesicles secreted by mesenchymal stem cells and primary tumor cells may primarily aid the shift of immune cells to a pro-oncogenic phenotype. Conversely, microvesicles released by tumor-adjacent tissues may have the opposite effect. Our review reveals that a specific noncoding RNA may affect oxidative stress by several mechanisms, which may have opposite effects on tumor growth. Furthermore, they may be involved in mechanisms other than regulating oxidative stress, which may level out their effects on oxidative stress and tumor growth. In addition, several noncoding RNAs might share a specific function, making it very unlikely that intervening with only one of these noncoding RNAs will block this particular mechanism. Overall, further validation of the interaction between noncoding RNAs about cancer types and stages of tumor development is warranted.

m6A readers, writers, erasers, and the m6A epitranscriptome in breast cancer

Epitranscriptomic modification of RNA regulates human development, health, and disease. The true diversity of the transcriptome in breast cancer including chemical modification of transcribed RNA (epitranscriptomics) is not well understood due to limitations of technology and bioinformatic analysis. N-6-methyladenosine (m6A) is the most abundant epitranscriptomic modification of mRNA and regulates splicing, stability, translation, and intracellular localization of transcripts depending on m6A association with reader RNA-binding proteins. m6A methylation is catalyzed by the METTL3 complex and removed by specific m6A demethylase ALKBH5, with the role of FTO as an 'eraser' uncertain. In this review, we provide an overview of epitranscriptomics related to mRNA and focus on m6A in mRNA and its detection. We summarize current knowledge on altered levels of writers, readers, and erasers of m6A and their roles in breast cancer and their association with prognosis. We summarize studies identifying m6A peaks and sites in genes in breast cancer cells.

Changes of Mutations and Copy-Number and Enhanced Cell Migration during Breast Tumorigenesis

Although cancer stem cells (CSCs) play a major role in tumorigenesis and metastasis, the role of genetic alterations in invasiveness of CSCs is still unclear. Tumor microenvironment signals, such as extracellular matrix (ECM) composition, significantly influence cell behaviors. Unfortunately, these signals are often lost in in vitro cell culture. This study determines putative CSC populations, examines genetic changes during tumorigenesis of human breast epithelial stem cells, and investigates single-cell migration properties on ECM-mimetic platforms. Whole exome sequencing data indicate that tumorigenic cells have a higher somatic mutation burden than non-tumorigenic cells, and that mutations exclusive to tumorigenic cells exhibit higher predictive deleterious scores. Tumorigenic cells exhibit distinct somatic copy number variations (CNVs) including gain of duplications in chromosomes 5 and 8. ECM-mimetic topography selectively enhances migration speed of tumorigenic cells, but not of non-tumorigenic cells, and results in a wide distribution of tumorigenic single-cell migration speeds, suggesting heterogeneity in cellular sensing of contact guidance cues. This study identifies mutations and CNVs acquired during breast tumorigenesis, which can be associated with enhanced migration of breast tumorigenic cells, and demonstrates that a nanotopographically-defined platform can be applied to recapitulate an ECM structure for investigating cellular migration in the simulated tumor microenvironment.

c-MYC mediates the crosstalk between breast cancer cells and tumor microenvironment

The MYC oncogenic family is dysregulated in diverse tumors which is generally linked to the poor prognosis of tumors. The members in MYC family are transcription factors which are responsible for the regulation of various genes expression. Among them, c-MYC is closely related to the progression of tumors. Furthermore, c-MYC aberrations is tightly associated with the prevalence of breast cancer. Tumor microenvironment (TME) is composed of many different types of cellular and non-cellular factors, mainly including cancer-associated fibroblasts, tumor-associated macrophages, vascular endothelial cells, myeloid-derived suppressor cells and immune cells, all of which can affect the diagnosis, prognosis, and therapeutic efficacy of breast cancer. Importantly, the biological processes occurred in TME, such as angiogenesis, immune evasion, invasion, migration, and the recruition of stromal and tumor-infiltrating cells are under the modulation of c-MYC. These findings indicated that c-MYC serves as a critical regulator of TME. Here, we aimed to summarize and review the relevant research, thus to clarify c-MYC is a key mediator between breast cancer cells and TME. Video Abstract.

"Pulsed Hypoxia" Gradually Reprograms Breast Cancer Fibroblasts into Pro-Tumorigenic Cells via Mesenchymal-Epithelial Transition

Hypoxia arises in most growing solid tumors and can lead to pleotropic effects that potentially increase tumor aggressiveness and resistance to therapy through regulation of the expression of genes associated with the epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET). The main goal of the current work was to obtain and investigate the intermediate phenotype of tumor cells undergoing the hypoxia-dependent transition from fibroblast to epithelial morphology. Primary breast cancer fibroblasts BrC4f, being cancer-associated fibroblasts, were subjected to one or two rounds of "pulsed hypoxia" (PH). PH induced transformation of fibroblast-shaped cells to semi-epithelial cells. Western blot analysis, fluorescent microscopy and flow cytometry of transformed cells demonstrated the decrease in the mesenchymal markers vimentin and N-cad and an increase in the epithelial marker E-cad. These cells kept mesenchymal markers αSMA and S100A4 and high ALDH activity. Real-time PCR data of the cells after one (BrC4f_Hyp1) and two (BrC4f_Hyp2) rounds of PH showed consistent up-regulation of TWIST1 gene as an early response and ZEB1/2 and SLUG transcriptional activity as a subsequent response. Reversion of BrC4f_Hyp2 cells to normoxia conditions converted them to epithelial-like cells (BrC4e) with decreased expression of EMT genes and up-regulation of MET-related OVOL2 and c-MYC genes. Transplantation of BrC4f and BrC4f_Hyp2 cells into SCID mice showed the acceleration of tumor growth up to 61.6% for BrC4f_Hyp2 cells. To summarize, rounds of PH imitate the MET process of tumorigenesis in which cancer-associated fibroblasts pass through intermediate stages and become more aggressive epithelial-like tumor cells.

Methods for assessing the effect of microRNA on stemness genes

According to the latest concepts, for micrometastasis to develop into macrometastasis, differentiated cancer cells must revert to a dedifferentiated state. Activation of stemness genes plays a key role in this transition. Suppression of stemness gene expression using microRNAs can become the basis for the development of effective anti-metastatic drugs. This article provides an overview of the existing methods for assessing the effect of microRNAs on stemness genes and cancer cell dedifferentiation.

The BET inhibitor/degrader ARV-825 prolongs the growth arrest response to Fulvestrant + Palbociclib and suppresses proliferative recovery in ER-positive breast cancer

Anti-estrogens or aromatase inhibitors in combination with cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors are the current standard of care for estrogen receptor-positive (ER+) Her-2 negative metastatic breast cancer. Although these combination therapies prolong progression-free survival compared to endocrine therapy alone, the growth-arrested state of residual tumor cells is clearly transient. Tumor cells that escape what might be considered a dormant or quiescent state and regain proliferative capacity often acquire resistance to further therapies. Our studies are based upon the observation that breast tumor cells arrested by Fulvestrant + Palbociclib enter into states of both autophagy and senescence from which a subpopulation ultimately escapes, potentially contributing to recurrent disease. Autophagy inhibition utilizing pharmacologic or genetic approaches only moderately enhanced the response to Fulvestrant + Palbociclib in ER+ MCF-7 breast tumor cells, slightly delaying proliferative recovery. In contrast, the BET inhibitor/degrader, ARV-825, prolonged the growth arrested state in both p53 wild type MCF-7 cells and p53 mutant T-47D cells and significantly delayed proliferative recovery. In addition, ARV-825 added after the Fulvestrant + Palbociclib combination promoted apoptosis and demonstrated efficacy in resistant RB deficient cell lines. These studies indicate that administration of BET inhibitors/degraders, which are currently being investigated in multiple clinical trials, may potentially improve standard of care therapy in metastatic ER+ breast cancer patients and may further prolong progression-free survival.

Strategies to target the cancer driver MYC in tumor cells

The MYC oncoprotein functions as a master regulator of cellular transcription and executes non-transcriptional tasks relevant to DNA replication and cell cycle regulation, thereby interacting with multiple proteins. MYC is required for fundamental cellular processes triggering proliferation, growth, differentiation, or apoptosis and also represents a major cancer driver being aberrantly activated in most human tumors. Due to its non-enzymatic biochemical functions and largely unstructured surface, MYC has remained difficult for specific inhibitor compounds to directly address, and consequently, alternative approaches leading to indirect MYC inhibition have evolved. Nowadays, multiple organic compounds, nucleic acids, or peptides specifically interfering with MYC activities are in preclinical or early-stage clinical studies, but none of them have been approved so far for the pharmacological treatment of cancer patients. In addition, specific and efficient delivery technologies to deliver MYC-inhibiting agents into MYC-dependent tumor cells are just beginning to emerge. In this review, an overview of direct and indirect MYC-inhibiting agents and their modes of MYC inhibition is given. Furthermore, we summarize current possibilities to deliver appropriate drugs into cancer cells containing derailed MYC using viral vectors or appropriate nanoparticles. Finding the right formulation to target MYC-dependent cancers and to achieve a high intracellular concentration of compounds blocking or attenuating oncogenic MYC activities could be as important as the development of novel MYC-inhibiting principles.

Molecular characterization of early breast cancer onset to understand disease phenotypes in African patients

Female breast cancer (BC) is the leading cause of cancer-related deaths worldwide with higher mortality rates and early onset in developing countries. The molecular basis of early disease onset is still elusive. We recruited 472 female breast cancer from two sub-Saharan African countries (Cameroon and Congo) between 2007 and 2018 and collected clinical data from these patients. To investigate the molecular drivers of early disease onset, we analyzed publicly available breast cancer molecular data from the cancer genome atlas (TCGA) and the gene expression omnibus (GEO) for copy number alteration, mutation and gene expression. Early BC onset (EOBRCA) (diagnosis before 45 years) was higher in African women compared with the TCGA cohort (51.7% vs 15.6%). The tumor grade, mitotic index, HER2 + phenotype, basal-like phenotype and ki67 were higher in EOBRCA for all cohorts. BC risk factors such as parity, breastfeeding early onset of menarche and use of hormonal contraceptives were significantly associated with EOBRCA (p < 0.05). EOBRCA was equally associated with copy number alterations in several oncogenes including CDH6 and FOXM1 and tumor suppressor including TGM3 and DMBT1 as well as higher TP53 mutation rates (OR: 2.93, p < 0.01). There was a significant enrichment of TGFß signaling in EOBRCA with TGM3 deletions, which was associated with high expression of all SMAD transcription factors as well as WNT ligands. The Frizzled receptors FZD1, FZD4 and FZD6 were significantly upregulated in EOBRCA, suggesting activation of non-canonical WNT signaling. Our data, suggest the implication of TGM3 deletion in early breast cancer onset. Further molecular investigations are warranted in African patients.

MF-094 nanodelivery inhibits oral squamous cell carcinoma by targeting USP30

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a common head and neck cancer, and the incidence of OSCC is increasing. As the mortality of OSCC keeps increasing, it is crucial to clarify its pathogenesis and develop new therapeutic strategies.

METHODS

Confocal laser scanning microscopy was used to evaluate the uptake of nanoparticles (NPs). The potential functions of USP30 were evaluated by cell counting kit (CCK)-8, flow cytometry, biochemical assay, coimmunoprecipitation, qRT-PCR, and immunoblotting. The antitumor effect of NP-loaded USP30 inhibitor MF-094 was evaluated in vitro and in vivo.

RESULTS

In this study, increased USP30 expression was found in OSCC specimens and cell lines through qRT-PCR and immunoblotting. CCK-8, flow cytometry, and biochemical assay revealed that the deubiquitylated catalytic activity of USP30 contributed to cell viability and glutamine consumption of OSCC. Subsequently, USP30 inhibitor MF-094 was loaded in ZIF-8-PDA and PEGTK to fabricate ZIF-8-PDA-PEGTK nanoparticles, which exhibited excellent inhibition of cell viability and glutamine consumption of OSCC, both in vitro and in vivo.

CONCLUSION

The results indicated the clinical significance of USP30 and showed that nanocomposites provide a targeted drug delivery system for treating OSCC.

Targeting the MDM2-p53 pathway in dedifferentiated liposarcoma

Dedifferentiated liposarcoma (DDLPS) is an aggressive adipogenic cancer with poor prognosis. DDLPS tumors are only modestly sensitive to chemotherapy and radiation, and there is a need for more effective therapies. Genetically, DDLPS is characterized by a low tumor mutational burden and frequent chromosomal structural abnormalities including amplification of the 12q13-15 chromosomal region and the MDM2 gene, which are defining features of DDLPS. The MDM2 protein is an E3 ubiquitin ligase that targets the tumor suppressor, p53, for proteasomal degradation. MDM2 amplification or overexpression in human malignancies is associated with cell-cycle progression and worse prognosis. The MDM2-p53 interaction has thus garnered interest as a therapeutic target for DDLPS and other malignancies. MDM2 binds p53 via a hydrophobic protein interaction that is easily accessible with synthetic analogues. Multiple agents have been developed, including Nutlins such as RG7112 and small molecular inhibitors including SAR405838 and HDM201. Preclinical in vitro and animal models have shown promising results with MDM2 inhibition, resulting in robust p53 reactivation and cancer cell death. However, multiple early-phase clinical trials have failed to show a benefit with MDM2 pathway inhibition for DDLPS. Mechanisms of resistance are being elucidated, and novel inhibitors and combination therapies are currently under investigation. This review provides an overview of these strategies for targeting MDM2 in DDLPS.

HAS2-Ezrin-ER axis plays a role in acquired antiestrogen resistance of ER-positive breast cancer

The development of endocrine resistance is a major clinical problem in estrogen receptor-positive (ER+) breast cancer (BrCa) treatment, in which how cancer cells acquire resistance remains obscure. Hyaluronan synthase 2 (HAS2) is the most critical synthase in producing hyaluronan and is well known for its involvement in cancer growth, metabolism and metastasis. Recent evidence has proved that HAS2 is involved in cellular acquired resistance to drug therapy in BrCa. In this work, we first observed that HAS2 expression was decreased in the endocrine-resistant ER+ BrCa cells. Further knocking-out experiments confirmed that the loss of HAS2 in parental ER+ BrCa cells resulted in a following antiestrogen resistance. Next, we found that the HAS2-loss could induce an upregulation of Ezrin, a member of the membrane cytoskeletal protein family who plays key roles in cellular signal transduction. Notably, we identified that the increase of Ezrin induced by HAS2-loss could inhibit the ERα expression and augment antiestrogen resistance, suggesting that a HAS2-Ezrin-ER axis may be associated with the acquirement of endocrine resistance in ER+ BrCa cells. Finally, knockdown or inhibition of Ezrin could restore the sensitivity of endocrine-resistant cells to antiestrogens treatment by activating ERα signaling. Taken together, our findings unraveled a novel HAS2-Ezrin-ER route in regulating the sensitivity of ER+ BrCa cells to antiestrogens, in which Ezrin may be a potential target in endocrine therapy.

ZNF33A Promotes Tumor Progression and BET Inhibitor Resistance in Triple-Negative Breast Cancer

Overexpression of ZNF33A (Krüppel-type zinc finger 33A) promotes carcinogenesis in several malignant tumors. However, the biochemical role and clinical importance of ZNF33A in triple-negative breast cancer (TNBC) still need to be explored. In this study, overexpression of ZNF33A in TNBC patient tissues and cell lines led to a worse prognosis. ZNF33A promoted cell growth and facilitated the resistance of cancer cells to inhibitors of bromodomain and extraterminal domain (BET) in TNBC. ZNF33A also promoted the induction of c-Myc, the primary player for the resistance to BET inhibitors in TNBC. In conclusion, ZNF33A may be a tumor growth-promoting factor associated with TNBC prognosis, and ZNF33A repression may sensitize TNBC cells to BET inhibitors.

Concise review: Cancer cell reprogramming and therapeutic implications

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The cancer stem cell (CSC) act as tumor initiating cells.

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Reprogramming technology can convert cells into CSCs.

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Metabolic reprogramming is critical for CSCs.

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MiRNA can mediate cancer cell reprogramming as emerging alternatives.

The cancer stem cell (CSC) hypothesis postulates that cancer originates from the malignant transformation of stem cells and is considered to apply to a variety of cancers. Additionally, cancer cells alter metabolic processes to sustain their characteristic uncontrolled growth and proliferation. Further, microRNAs (miRNAs) are found to be involved in acquisition of stem cell-like properties, regulation and reprogramming of cancer cells during cancer progression through its post-transcriptional-regulatory activity. In this concise review, we aim to integrate the current knowledge and recent advances to elucidate the mechanisms involved in the regulation of cell reprogramming and highlights the potential therapeutic implications for the future.

Oncogenic and Stemness Signatures of the High-Risk HCMV Strains in Breast Cancer Progression

Simple Summary

Lately, human cytomegalovirus (HCMV) has been progressively implicated in carcinogenesis alongside its oncomodulatory impact. CMV-Transformed Human mammary epithelial cells (CTH) phenotype might be defined by giant cell cycling, whereby the generation of polyploid giant cancer cells (PGCCs) could expedite the acquisition of malignant phenotypes. Herein, the main study objectives were to assess the transformation potential in vitro and evaluate the obtained cellular phenotype, the genetic and molecular features, and the activation of cellular stemness programs of HCMV strains, B544 and B693, which were previously isolated from triple-negative breast cancer (TNBC) biopsies. The strains’ sensitivity to paclitaxel and ganciclovir combination therapy was evaluated. A unique molecular landscape was unveiled in the tumor microenvironment of TNBC harboring high-risk HCMV. Overall, the explicit oncogenic and stemness signatures highlight HCMV potential in breast cancer progression thus paving the way for targeted therapies and clinical interventions which prolong the overall survival of breast cancer patients.

Abstract

Background: Human cytomegalovirus (HCMV) oncomodulation, molecular mechanisms, and ability to support polyploid giant cancer cells (PGCCs) generation might underscore its contribution to oncogenesis, especially breast cancers. The heterogeneity of strains can be linked to distinct properties influencing the virus-transforming potential, cancer types induced, and patient’s clinical outcomes. Methods: We evaluated the transforming potential in vitro and assessed the acquired cellular phenotype, genetic and molecular features, and stimulation of stemness of HCMV strains, B544 and B693, isolated from EZH2^HighMyc^High triple-negative breast cancer (TNBC) biopsies. Therapeutic response assessment after paclitaxel (PTX) and ganciclovir (GCV) treatment was conducted in addition to the molecular characterization of the tumor microenvironment (TME). Findings: HCMV-B544 and B693 transformed human mammary epithelial cells (HMECs). We detected multinucleated and lipid droplet-filled PGCCs harboring HCMV. Colony formation was detected and Myc was overexpressed in CMV-Transformed-HMECs (CTH cells). CTH-B544 and B693 stimulated stemness and established an epithelial/mesenchymal hybrid state. HCMV-IE1 was detected in CTH long-term cultures indicating a sustained viral replication. Biopsy B693 unveiled a tumor signature predicting a poor prognosis. CTH-B544 cells were shown to be more sensitive to PTX/GCV therapy. Conclusion: The oncogenic and stemness signatures of HCMV strains accentuate the oncogenic potential of HCMV in breast cancer progression thereby leading the way for targeted therapies and innovative clinical interventions that will improve the overall survival of breast cancer patients.

Circulating Tumor DNA After Neoadjuvant Chemotherapy in Breast Cancer Is Associated With Disease Relapse

PURPOSE

Detection of circulating tumor DNA (ctDNA) after neoadjuvant chemotherapy in patients with early-stage breast cancer may allow for early detection of relapse. In this study, we analyzed ctDNA using a personalized, tumor-informed multiplex polymerase chain reaction-based next-generation sequencing assay.

METHODS

Plasma samples (n = 157) from 44 patients were collected before neoadjuvant therapy (baseline), after neoadjuvant therapy and before surgery (presurgery), and serially postsurgery including a last follow-up sample. The primary end point was event-free survival (EFS) analyzed using Cox regression models.

RESULTS

Thirty-eight (86%), 41 (93%), and 38 (86%) patients had baseline, presurgical, and last follow-up samples, respectively. Twenty patients had hormone receptor-positive/human epidermal growth factor receptor 2-negative, 13 had triple-negative breast cancer, and 11 had human epidermal growth factor receptor 2-positive disease. Baseline ctDNA detection was observed in 22/38 (58%) patients and was significantly associated with Ki67 > 20% (P = .036) and MYC copy-number gain (P = .0025, false discovery rate = 0.036). ctDNA detection at presurgery and at last follow-up was observed in 2/41 (5%) and 2/38 (5%) patients, respectively. Eight relapses (seven distant and one local) were noted (median follow-up 3.03 years [range, 0.39-5.85 years]). After adjusting for pathologic complete response (pCR), ctDNA detection at presurgery and at last follow-up was associated with shorter EFS (hazard ratio [HR], 53; 95% CI, 4.5 to 624; P < .01, and HR, 31; 95% CI, 2.7 to 352; P < .01, respectively). Association between baseline detection and EFS was not observed (HR, 1.4; 95% CI, 0.3 to 5.9; P = .67).

CONCLUSION

The presence of ctDNA after neoadjuvant chemotherapy is associated with relapse in early-stage breast cancer, supporting interventional trials for testing the clinical utility of ctDNA monitoring in this setting.

Autophagy genes CCL2 and MYC are considered as potential biomarkers for pulmonary embolism

OBJECTIVE

The pathogenesis of pulmonary embolism (PE) remains unclear. This study was designed to determine the differential genes associated with PE autophagy via the gene expression omnibus (GEO).

METHODS

Microarray data sets GSE11851 and GSE13535 were downloaded from the GEO to determine the differentially expressed genes (DEGs) of PE, and the protein-protein interaction (PPI) and hub gene networks were constructed by string and Cytoscape software. Additionally, the two data sets were screened to find the autophagy-related genes with common differential expression. Then, autophagy-related hub genes (ARHGs) overlapping with autophagy-related genes and hub genes were identified. Next, the mRNA-miRNA network was constructed, and finally the expressions of hub genes were determined with GSE11851 and GSE13535.

RESULTS

A total of 235 common DEGs were identified, and C-C motif chemokine ligand 2 (CCL2) and MYC proto-oncogene (MYC) were identified to be the ARHGs of PE. Additionally, a co-expression network of mRNAs and miRNAs, consisting of 94 nodes and 103 edges, was constructed by Cytoscape. PE samples showed significantly higher expressions of CCL2 and MYC than the control samples (P < 0.05). According to gene set enrichment analysis (GSEA), CCL2 was closely correlated with oxidative stress and inflammatory reaction, while MYC was closely correlated with inflammatory reaction.

CONCLUSION

According to analysis, CCL2 and MYC, with high expression in PE samples, are promising potential markers of PE.

Genomic characterization and tumor evolution in paired samples of metaplastic breast carcinoma

Metaplastic breast carcinomas are a rare and heterogeneous group of tumors (0.5-2%). They are mainly triple negative tumors but they present poorer chemotherapy responses and worse prognosis than other triple negative tumors. The aim of our study was to characterize the molecular profile and tumor evolution in matched (primary-relapse) tumor samples from patients with early-stage metaplastic breast carcinomas who had disease recurrence/progression. We performed genomic profiling of tumor biopsies at least from two different time points of their tumor evolution. Tumor samples were analyzed by DNA-Next Generation Sequencing (Illumina 2 x 75bp) using the Action OncoKitDX panel (Imegen-Health in Code group), which includes point mutations in 50 genes, CNVs, and fusion genes. Only pathogenic and likely pathogenic variants were considered for analysis and they were categorized following the ComPerMed criteria. We analyzed 21 matched tumor samples (8 primary and 13 relapse/progression samples). Genomic profiling of matched tumor samples revealed that mutations present in primary tumors are generally maintained in the relapse/disease progression. We did not find a significant increase in point mutations between primary and relapse/progression samples, although gene amplifications were found more frequently in relapse/progression samples. Tumor samples harbored high frequency of TP53 (100%) and TERT promoter (29%) mutations, and of MYC amplifications (80% of which in relapse/progression samples). No PI3KCA mutations were found, but PTEN variations were enriched in 38% of samples (10% mutations and 28% deletions). FGFR1 amplifications were identified in 13% of samples (primary tumor only). Neither ERBB2 nor EGFR gene amplifications were detected. The most frequent pathogenic alterations occurred in cycle regulation's genes, including TP53 and TERT promoter mutations, and MYC amplifications. Relapse/progression samples were highly enriched for MYC amplification. Larger studies are required to better characterize these tumors, and identify new strategies to improve the prognosis of these patients.

HMGN4 plays a key role in STAT3-mediate oncogenesis of triple-negative breast cancer

High-mobility group nucleosome-binding domain 4 (HMGN4) exerts biological functions by regulating gene transcription through binding with nucleosome. As a new epigenetic regulator discovered in 2001, its biological functions have not been clarified. HMGN4 belongs to HMGNs family, in which HMGN1, 2, and 5 have been reported to play roles in oncogenesis of various cancers. However, it is reported that HMGN4 was associated with thyroid and liver cancer. In this study, we discovered for the first time that HMGN4 was highly expressed in human triple-negative breast cancer (TNBC), based on the analysis of the TCGA database. Moreover, we found that HMGN4 controlled the proliferation of human TNBC cells both in vitro and in vivo. Mechanistically, the positive correlation occurred between HMGN4 and STAT3 downstream genes while HMGN4 played an indispensable role in constitutively active STAT3 (STAT3C) induced colony formation. Interestingly, we reported that STAT3 regulated HMGN4 transcription as its transcriptional factor by ChIP and HMGN4 promoter-luc assays. That is to say, there is a feed-forward signaling circuit between HMGN4 and STAT3, which might control TNBC cell growth. Finally, we proved that the interference of HMGN4 by nanovehicle-packaged siRNA may be a potentially effective approach in TNBC treatment. In summary, our findings not only identified a novel regulator in TNBC cell proliferation but also revealed the mechanism by which HMGN4 acted as a downstream gene of STAT3 to participate in the STAT3 pathway, which indicated that HMGN4 was likely to be a potential novel target for anti-TNBC therapy.

Exploring the roles of the Cdc2-like kinases in cancers

The Cdc2-like kinases (CLKs 1-4) are involved in regulating the alternative splicing of a variety of genes. Their activity contributes to important cellular processes such as proliferation, differentiation, apoptosis, migration, and cell cycle regulation. Abnormal expression of CLKs can lead to cancers; therefore, pharmacological inhibition of CLKs may be a useful therapeutic strategy. This review summarises what is known about the roles of each of the CLKs in cancerous cells, as well as the effects of relevant small molecule CLK inhibitors.

Targeting cyclin-dependent kinase 9 in cancer therapy

Cyclin-dependent kinase (CDK) 9 associates mainly with cyclin T1 and forms the positive transcription elongation factor b (p-TEFb) complex responsible for transcriptional regulation. It has been shown that CDK9 modulates the expression and activity of oncogenes, such as MYC and murine double minute 4 (MDM4), and it also plays an important role in development and/or maintenance of the malignant cell phenotype. Malfunction of CDK9 is frequently observed in numerous cancers. Recent studies have highlighted the function of CDK9 through a variety of mechanisms in cancers, including the formation of new complexes and epigenetic alterations. Due to the importance of CDK9 activation in cancer cells, CDK9 inhibitors have emerged as promising candidates for cancer therapy. Natural product-derived and chemically synthesized CDK9 inhibitors are being examined in preclinical and clinical research. In this review, we summarize the current knowledge on the role of CDK9 in transcriptional regulation, epigenetic regulation, and different cellular factor interactions, focusing on new advances. We show the importance of CDK9 in mediating tumorigenesis and tumor progression. Then, we provide an overview of some CDK9 inhibitors supported by multiple oncologic preclinical and clinical investigations. Finally, we discuss the perspective and challenge of CDK9 modulation in cancer.

Research Progress on G-Quadruplexes in Human Telomeres and Human Telomerase Reverse Transcriptase (hTERT) Promoter

The upregulation telomerase activity is observed in over 85-90% of human cancers and provides an attractive target for cancer therapies. The high guanine content in the telomere DNA sequences and the hTERT promoter can form G-quadruplexes (G4s). Small molecules targeting G4s in telomeres and hTERT promoter could stabilize the G4s and inhibit hTERT expression and telomere extension. Several G4 ligands have shown inhibitory effects in cancer cells and xenograft mouse models, indicating these ligands have a potential for cancer therapies. The current review article describes the concept of the telomere, telomerase, and G4s. Moreover, the regulation of telomerase and G4s in telomeres and hTERT promoter is discussed as well. The summary of the small molecules targeting G4s in telomeric DNA sequences and the hTERT promoter will also be shown.

Polyploid giant cancer cells, EZH2 and Myc upregulation in mammary epithelial cells infected with high-risk human cytomegalovirus

Background

Human cytomegalovirus (HCMV) infection has been actively implicated in complex neoplastic processes. Beyond oncomodulation, the molecular mechanisms that might underlie HCMV-induced oncogenesis are being extensively studied. Polycomb repressive complex 2 (PRC2) proteins, in particular enhancer of zeste homolog 2 (EZH2) are associated with cancer progression. Nevertheless, little is known about EZH2 activation in the context of HCMV infection and breast oncogenesis.

Methods

Herein, we identified EZH2 as a downstream target for HCMV-induced Myc upregulation upon acute and chronic infection with high-risk strains using a human mammary epithelial model.

Findings

We detected polyploidy and CMV-transformed HMECs (CTH) cells harboring HCMV and dynamically undergoing the giant cells cycle. Acquisition of embryonic stemness markers positively correlated with EZH2 and Myc expression. EZH2 inhibitors curtail sustained CTH cells’ malignant phenotype. Besides harboring polyploid giant cancer cells (PGCCs), tumorigenic breast biopsies were characterized by an enhanced EZH2 and Myc expression, with a strong positive correlation between EZH2 and Myc expression, and between PGCC count and EZH2/Myc expression in the presence of HCMV. Further, we isolated two HCMV strains from EZH2^HighMyc^High basal-like tumors which replicate in MRC5 cells and transform HMECs toward CTH cells after acute infection.

Interpretation

Our data establish a potential link between HCMV-induced Myc activation, the subsequent EZH2 upregulation, and polyploidy induction. These data support the proposed tumorigenesis properties of EZH2/Myc, and allow the isolation of two oncogenic HCMV strains from EZH2^HighMyc^High basal breast tumors while identifying EZH2 as a potential therapeutic target in the management of breast cancer, particularly upon HCMV infection.

Funding

This work was supported by grants from the University of Franche-Comté (UFC) (CR3300), the Région Franche-Comté (2021-Y-08292 and 2021-Y-08290) and the Ligue contre le Cancer (CR3304) to Georges Herbein. Zeina Nehme is a recipient of a doctoral scholarship from the municipality of Habbouch. Sandy Haidar Ahmad is recipient of a doctoral scholarship from Lebanese municipality. Ranim El Baba is a recipient of a doctoral scholarship from Hariri foundation for sustainable human development.