A role for glial cell derived neurotrophic factor induced expression by inflammatory cytokines and RET/GFR alpha 1 receptor up-regulation in breast cancer

Molecular classification of hormone receptor-positive /HER2-positive breast cancer reveals potential neoadjuvant therapeutic strategies

Significant heterogeneity exists in hormone receptor (HR)-positive/HER2-positive (HR+/HER2+) breast cancer, contributing to suboptimal pathological complete response rates with conventional neoadjuvant treatment regimens. Overcoming this challenge requires precise molecular classification, which is pivotal for the development of targeted therapies. We conducted molecular typing on a cohort of 211 patients with HR+/HER2+ breast cancer and performed a comprehensive analysis of the efficacy of various neoadjuvant treatment regimens. Our findings revealed four distinct molecular subtypes, each exhibiting unique characteristics and therapeutic implications. The HER2-enriched subtype, marked by activation of the HER2 signaling and hypoxia-inducible factor 1 (HIF-1) pathway, may benefit from intensified anti-HER2-targeted therapy. Estrogen receptor (ER)-activated subtype demonstrated potential sensitivity to combined therapeutic strategies targeting both ER and HER2 pathways. Characterized by high immune cell infiltration, the immunomodulatory subtype showed sensitivity to HER2-targeted antibody-drug conjugates (ADCs) and promise for immune checkpoint therapy. The highly heterogeneous subtype requires a multifaceted therapeutic approach. Organoid susceptibility assays suggested phosphoinositide 3-kinase inhibitors may be a potential treatment option. These findings underscore the importance of molecular subtyping in HR+/HER2+ breast cancer, offering a framework for developing precise and personalized treatment strategies. By addressing the heterogeneity of the disease, these approaches have the potential to optimize therapeutic outcomes and improve patient care.

Breast Cancer Risk and Management in the Endocrine Clinic: A Comprehensive Review

OBJECTIVE

This review seeks to provide endocrine clinicians with a comprehensive analysis of breast cancer risk, diagnostic modalities and management strategies in women with endocrine disorders, with particular emphasis on the influence of metabolic factors such as diabetes and obesity, and the role of Menopausal Hormone Therapy (MHT).

DESIGN

The review examines a spectrum of endocrine disorders commonly encountered in clinical practice, including Multiple Endocrine Neoplasia Types 1 (MEN1), 2 (MEN2) and 4 (MEN4), Von Hippel-Lindau syndrome (VHL), Pheochromocytoma and Paraganglioma (PPGL), Acromegaly, Hyperprolactinaemia, Polycystic Ovary Syndrome (PCOS), Congenital Adrenal Hyperplasia (CAH), Turner Syndrome, alongside metabolic conditions such as diabetes and obesity and the effects of MHT. The review critically appraises each disorder's association with breast cancer risk, screening implications and therapeutic management.

PATIENTS

This analysis focuses on women with the aforementioned endocrine and metabolic disorders, assessing their specific breast cancer risk profiles, informed by the latest clinical evidence and molecular insights.

MEASUREMENTS

The review comprehensively evaluates current evidence-based approaches to screening, diagnostic accuracy and treatment in this patient cohort. Emphasis is placed on the metabolic derangements, hormonal influences and genetic predispositions that modulate breast cancer risk, providing disorder-specific recommendations for individualised care.

RESULTS

The findings indicate a significantly elevated breast cancer risk in patients with MEN1, necessitating early initiation of MRI screening by age 40. In MEN2, emerging evidence suggests that combining RET inhibitors with endocrine therapy may yield clinical benefits, although further research is needed to validate this approach. The breast cancer risk associated with MEN4 and VHL syndromes, while documented, remains less well-characterised, requiring further investigation. Diabetes and obesity are confirmed as major modifiable risk factors, particularly in postmenopausal women, where hyperinsulinemia and metabolic dysfunction contribute to increased incidence and poorer outcomes, notably in triple-negative breast cancer (TNBC). The role of MHT, particularly combined oestrogen-progestogen therapy, is strongly associated with increased breast cancer risk, particularly for hormone receptor-positive malignancies, necessitating cautious use and personalised treatment planning. In contrast, oestrogen-only MHT appears to confer a reduced risk in women post-hysterectomy. For patients with PCOS, CAH and Turner Syndrome, while definitive evidence of elevated breast cancer risk is lacking, individualised screening strategies and careful hormone therapy management remain essential due to the complex interplay of hormonal and metabolic factors.

CONCLUSIONS

The review highlights the need for personalised breast cancer screening and management protocols in women with endocrine and metabolic disorders. For high-risk groups such as MEN1 patients, early initiation of MRI screening is warranted. In women with diabetes and obesity, targeted interventions addressing hyperinsulinemia and metabolic dysfunction are critical to mitigating their increased cancer risk. The association between MHT and breast cancer underscores the importance of individualised risk stratification in hormone therapy administration, particularly in women with predisposing genetic or endocrine conditions. Enhanced surveillance tailored to the unique risk profiles of endocrine disorder patients will facilitate early detection and improve clinical outcomes. However, further large-scale studies are necessary to refine these associations and develop robust, evidence-based guidelines.

Thyroid C-Cell Biology and Oncogenic Transformation

The thyroid parafollicular cell, or commonly named "C-cell," functions in serum calcium homeostasis. Elevations in serum calcium trigger release of calcitonin from the C-cell, which in turn functions to inhibit absorption of calcium by the intestine, resorption of bone by the osteoclast, and reabsorption of calcium by renal tubular cells. Oncogenic transformation of the thyroid C-cell is thought to progress through a hyperplastic process prior to malignancy with increasing levels of serum calcitonin serving as a biomarker for tumor burden. The discovery that Multiple Endocrine Neoplasia, type 2 is caused by activating mutations of the RET gene serves to highlight the RET-RAS-MAPK signaling pathway in both initiation and progression of medullary thyroid carcinoma. Thyroid C-cells are known to express RET at high levels relative to most cell types, therefore aberrant activation of this receptor is targeted primarily to the C-cell, providing one possible cause of tissue-specific oncogenesis. The role of RET signaling in normal C-cell function is unknown though calcitonin gene transcription appears to be sensitive to RET activation. Beyond RET the modeling of oncogenesis in animals and screening of human tumors for candidate gene mutations has uncovered mutation of RAS family members and inactivation of RB1 regulatory pathway as potential mediators of C-cell transformation. More recently, the integration of multiple biological layers of omics studies has uncovered new pathways of oncogenesis. A growing understanding of how RET interacts with these pathways, both in normal C-cell function and during oncogenic transformation, will help in the development of novel molecular targeted therapies.

A review on tyrosine kinase inhibitors for targeted breast cancer therapy

Breast cancer is a heterogeneous disease with complex molecular pathogenesis. Overexpression of several tyrosine kinase receptors is associated with poor prognosis, therefore, they can be key targets in breast cancer therapy. Tyrosine kinase inhibitors (TKIs) have emerged as leading agents in targeted cancer therapy due to their effectiveness in disrupting key molecular pathways involved in tumor growth. TKIs target various tyrosine kinases, including the human epidermal growth factor receptor 2 (HER2), epidermal growth factor receptor (EGFR), Vascular endothelial growth factor receptor (VEGFR), anaplastic lymphoma kinase (ALK), vascular endothelial growth factor receptor (VEGFR)-associated multi-targets, rearranged during transfection (RET), fibroblast growth factor receptor (FGFR), receptor tyrosine kinase-like orphan signal 1 (ROS1), Mitogen-activated protein kinase (MAPK), and tropomyosin receptor kinase (TRK). These drugs target the tyrosine kinase domain of receptor tyrosine kinases and play a vital role in proliferation and migration of breast cancer cells. Several TKIs, including lapatinib, neratinib, and tucatinib, have been developed and are currently used in clinical settings, often in combination with chemotherapy, endocrine therapy, or other targeted agents. TKIs have demonstrated remarkable benefits in enhancing progression-free and overall survival in patients with breast cancer and have become a standard of care for this population. This review provides an overview of TKIs currently being examined in preclinical studies and clinical trials, especially in combination with drugs approved for breast cancer treatment. TKIs have emerged as a promising therapeutic option for patients with breast cancer and hold potential for treating other breast cancer subtypes. The development of new TKIs and their integration into personalized treatment strategies will continue to shape the future of breast cancer therapy.

The causal relationship between 91 inflammatory cytokines and Gestational Diabetes Mmellitus: A bidirectional two-sample Mendelian randomization study

BACKGROUND

Gestational Diabetes Mellitus (GDM) poses significant risks to maternal and fetal health, yet its precise etiology remains unclear. Observational studies have demonstrated a link between specific inflammatory cytokines and the occurrence of GDM, but the causal relationships remain uncertain.

METHODS

Utilizing publicly accessible genetic data, we performed a bidirectional two-sample mendelian randomization (MR) analysis to elucidate the causal association between 91 inflammatory cytokines and GDM. Sensitivity analysis was carried out to evaluate the robustness, heterogeneity, and potential presence of horizontal pleiotropy within the results.

RESULTS

Elevated levels of Interleukin-7 (IL7) and Neurturin (NRTN) (OR=1.104, 95 % CI=1.003-1.216, p = 0.042; OR=1.102, 95 % CI=1.023-1.187, p = 0.010), along with decreased levels of Glial cell line-derived neurotrophic factor (GDNF), Interleukin-12 subunit beta (IL12β), and Interleukin-20 (IL20) (OR=0.911, 95 % CI=0.849-0.979, p = 0.010;OR=0.955, 95 % CI=0.916-0.996, p = 0.033; OR=0.892, 95 % CI=0.819-0.971, p = 0.008), are associated with increased GDM risk. Additionally, GDM occurrence correlates with increased Matrix metalloproteinase-10 (MMP-10) and decreased Interleukin-20 receptor subunit alpha (IL-20Rα) levels (OR=1.042, 95 % CI=1.002-1.084, p = 0.038; OR=0.949, 95 % CI=0.909-0.992, p = 0.021). Sensitivity analyses detected no significant heterogeneity or pleiotropy.

CONCLUSION

This study has clarified the causal link between inflammatory cytokines and GDM, thereby enhancing our comprehension of the potential mechanisms involved in GDM pathogenesis. These findings offer new insights into the etiology, diagnosis, and therapeutic strategies for GDM.

REThinking the role of the RET oncogene in breast cancer

The REarranged during Transfection (RET) receptor tyrosine kinase plays a crucial role in the development of various anatomical structures during embryogenesis and it is involved in many physiological cellular processes. This protein is also associated with the initiation of various cancer types, such as thyroid cancer, non-small cell lung cancer, and multiple endocrine neoplasms. In breast cancer, and especially in the estrogen receptor-positive (ER+) subtype, the activity of RET is of notable importance. Indeed, RET seems to be involved in tumor progression, resistance to therapies, and cellular proliferation. Nevertheless, the ways RET alterations could impact the prognosis of breast cancer and its response to treatment remain only partially elucidated. Several inhibitors of RET kinase have been developed thus far, with various degrees of selectivity toward RET inhibition. These molecules showed notable efficacy in the treatment of RET-driven tumors, including some breast cancer cases. Despite these encouraging results, further investigation is needed to fully understand the potential role RET inhibition in breast cancer. This review aims to recapitulate the existing evidence about the role of RET oncogene in breast cancer, from its pathogenic and potentially prognostic role, to the clinical applications of RET inhibitors.

Ashwagandha-Induced Programmed Cell Death in the Treatment of Breast Cancer

The aim of this review is to provide experimental evidence for the programmed-death activity of Ashwagandha (Withania somnifera) in the anti-cancer therapy of breast cancer. The literature search was conducted using online electronic databases (Google Scholar, PubMed, Scopus). Collection schedule data for the review article covered the years 2004-2024. Ashwagandha active substances, especially Withaferin A (WA), are the most promising anti-cancer compounds. WS exerts its effect on breast cancer cells by inducing programmed cell death, especially apoptosis, at the molecular level. Ashwagandha has been found to possess a potential for treating breast cancer, especially estrogen receptor/progesterone receptor (ER/PR)-positive and triple-negative breast cancer.

Genome-wide DNA methylation profiling in tongue squamous cell carcinoma

OBJECTIVES

To provide a comprehensive characterization of DNA methylome of oral tongue squamous cell carcinoma (OTSCC) and identify novel tumor-specific DNA methylation markers for early detection using saliva.

MATERIAL AND METHODS

Genome-wide DNA methylation analysis including six OTSCC matched adjacent non-tumoral tissue and saliva was performed using Infinium MethylationEPIC array. Differentially methylated levels of selected genes in our OTSCC cohort were further validated using OTSCC methylation data from The Cancer Genome Atlas database (TCGA). The methylation levels of a set of tumor-specific hypermethylated genes associated with a downregulated expression were evaluated in saliva. Receiver operating characteristic (ROC) curves were performed to assess the diagnostic value of DNA methylation markers.

RESULTS

A total of 25,890 CpGs (20,505 hypomethylated and 5385 hypermethylated) were differentially methylated (DMCpGs) between OTSCC and adjacent non-tumoral tissue. Hypermethylation of 11 tumor-specific genes was validated in OTSCC TCGA cohort. Of these 11 genes, A2BP1, ANK1, ALDH1A2, GFRA1, TTYH1, and PDE4B were also hypermethylated in saliva. These six salivary methylated genes showed high diagnostic accuracy (≥0.800) for discriminating patients from controls.

CONCLUSIONS

This is the first largest genome-wide DNA methylation study on OTSCC that identifies a group of novel tumor-specific DNA methylation markers with diagnostic potential in saliva.

Kinome Reprogramming Is a Targetable Vulnerability in ESR1 Fusion-Driven Breast Cancer

Transcriptionally active ESR1 fusions (ESR1-TAF) are a potent cause of breast cancer endocrine therapy (ET) resistance. ESR1-TAFs are not directly druggable because the C-terminal estrogen/anti-estrogen-binding domain is replaced with translocated in-frame partner gene sequences that confer constitutive transactivation. To discover alternative treatments, a mass spectrometry (MS)-based kinase inhibitor pulldown assay (KIPA) was deployed to identify druggable kinases that are upregulated by diverse ESR1-TAFs. Subsequent explorations of drug sensitivity validated RET kinase as a common therapeutic vulnerability despite remarkable ESR1-TAF C-terminal sequence and structural diversity. Organoids and xenografts from a pan-ET-resistant patient-derived xenograft model that harbors the ESR1-e6>YAP1 TAF were concordantly inhibited by the selective RET inhibitor pralsetinib to a similar extent as the CDK4/6 inhibitor palbociclib. Together, these findings provide preclinical rationale for clinical evaluation of RET inhibition for the treatment of ESR1-TAF-driven ET-resistant breast cancer.

SIGNIFICANCE

Kinome analysis of ESR1 translocated and mutated breast tumors using drug bead-based mass spectrometry followed by drug-sensitivity studies nominates RET as a therapeutic target. See related commentary by Wu and Subbiah, p. 3159.

Targeting the RET tyrosine kinase in neuroblastoma: A review and application of a novel selective drug design strategy

The RET (REarranged during Transfection) gene, which encodes for a transmembrane receptor tyrosine kinase, is an established oncogene associated with the etiology and progression of multiple types of cancer. Oncogenic RET mutations and rearrangements resulting in gene fusions have been identified in many adult cancers, including medullary and papillary thyroid cancers, lung adenocarcinomas, colon and breast cancers, and many others. While genetic RET aberrations are much less common in pediatric solid tumors, increased RET expression has been shown to be associated with poor prognosis in children with solid tumors such as neuroblastoma, prompting an interest in RET inhibition as a form of therapy for these children. A number of kinase inhibitors currently in use for patients with cancer have RET inhibitory activity, but these inhibitors also display activity against other kinases, resulting in unwanted side effects and limiting their safety and efficacy. Recent efforts have been focused on developing more specific RET inhibitors, but due to high levels of conservation between kinase binding pockets, specificity remains a drug design challenge. Here, we review the background of RET as a potential therapeutic target in neuroblastoma tumors and the results of recent preclinical studies and clinical trials evaluating the safety and efficacy of RET inhibition in adults and children. We also present a novel approach to drug discovery leveraging the chemical phenomenon of atropisomerism to develop specific RET inhibitors and present preliminary data demonstrating the efficacy of a novel RET inhibitor against neuroblastoma tumor cells.

Fulvestrant plus vandetanib versus placebo for the treatment of patients with metastatic breast cancer resistant to aromatase inhibitor therapy (FURVA): a multicentre, Phase 2, randomised controlled trial

BACKGROUND

FURVA, a randomised, double-blind Phase II trial, investigated whether the addition of vandetanib to fulvestrant improved progression-free survival (PFS) in patients with an aromatase inhibitor(AI)-resistant advanced breast cancer.

METHODS

Postmenopausal women with oestrogen receptor-positive (ER+ve)/HER2-negative advanced breast cancer, who experienced disease progression on an AI, were randomised (1:1) to fulvestrant 500 mg (Q28) with vandetanib 300 mg od (f + v) or placebo (f + p) until disease progression or discontinuation. The primary endpoint was PFS; secondary endpoints included overall survival (OS) and the influence of REarranged during Transfection (RET) signalling on outcomes.

RESULTS

In total, 165 participants were randomised to f + v (n = 80) or f + p (n = 85). Median PFS was 5.5 months (m) for f + v compared to 5.5 m for f + p (hazard ratio (HR) 0.88; 95% CI: 0.62-1.23; P = 0.22). Unexpectedly, high total RET expression was associated with a PFS advantage of 8.87 m vs 3.94 with low RET (HR 0.493: 95% CI 0.32-0.77; P = 0.002) independent of the treatment arm, supported by an OS advantage 21.95 m vs 18.04 (HR 0.584; 95% CI 0.34-1.00; P = 0.051) in the high-RET group.

CONCLUSION

The addition of vandetanib to fulvestrant does not improve PFS. However, high total RET expression was associated with improved PFS, suggesting RET may have a prognostic role in patients treated with fulvestrant.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02530411.

Supervised Relevance-Redundancy assessments for feature selection in omics-based classification scenarios

BACKGROUND AND OBJECTIVE

Many classification tasks in translational bioinformatics and genomics are characterized by the high dimensionality of potential features and unbalanced sample distribution among classes. This can affect classifier robustness and increase the risk of overfitting, curse of dimensionality and generalization leaks; furthermore and most importantly, this can prevent obtaining adequate patient stratification required for precision medicine in facing complex diseases, like cancer. Setting up a feature selection strategy able to extract only proper predictive features by removing irrelevant, redundant, and noisy ones is crucial to achieving valuable results on the desired task.

METHODS

We propose a new feature selection approach, called ReRa, based on supervised Relevance-Redundancy assessments. ReRa consists of a customized step of relevance-based filtering, to identify a reduced subset of meaningful features, followed by a supervised similarity-based procedure to minimize redundancy. This latter step innovatively uses a combination of global and class-specific similarity assessments to remove redundant features while preserving those differentiated across classes, even when these classes are strongly unbalanced.

RESULTS

We compared ReRa with several existing feature selection methods to obtain feature spaces on which performing breast cancer patient subtyping using several classifiers: we considered two use cases based on gene or transcript isoform expression. In the vast majority of the assessed scenarios, when using ReRa-selected feature spaces, the performances were significantly increased compared to simple feature filtering, LASSO regularization, or even MRmr - another Relevance-Redundancy method. The two use cases represent an insightful example of translational application, taking advantage of ReRa capabilities to investigate and enhance a clinically-relevant patient stratification task, which could be easily applied also to other cancer types and diseases.

CONCLUSIONS

ReRa approach has the potential to improve the performance of machine learning models used in an unbalanced classification scenario. Compared to another Relevance-Redundancy approach like MRmr, ReRa does not require tuning the number of preserved features, ensures efficiency and scalability over huge initial dimensionalities and allows re-evaluation of all previously selected features at each iteration of the redundancy assessment, to ultimately preserve only the most relevant and class-differentiated features.

Non-coding RNA's prevalence as biomarkers for prognostic, diagnostic, and clinical utility in breast cancer

Noncoding RNAs (ncRNAs), which make up a significant portion of the mammalian transcriptome and plays crucial regulatory roles in expression of genes and other biological processes, have recently been found. The most extensively researched of the sncRNAs, microRNAs (miRNAs), have been characterized in terms of their synthesis, roles, and significance in the tumor development. Its crucial function in the stem cell regulation, another class of sncRNAs known as aspirRNAs, has attracted attention in cancer research. The investigations have shown that long non-coding RNAs have a crucial role in controlling developmental stages, such as mammary gland development. Additionally, it has been discovered that lncRNA dysregulation precedes the development of several malignancies, including breast cancer. The functions of sncRNAs (including miRNAs and piRNAs) and lncRNAs in the onset and development of the breast cancer are described in this study. Additionally, future perspectives of various ncRNA-based diagnostic, prognostic, and therapeutic approaches also discussed.

Trioxacarcin A Interactions with G-Quadruplex DNA Reveal Its Potential New Targets as an Anticancer Agent

Trioxacarcin (TXN) A was reported to be an anticancer agent through alkylation of dsDNA. G-quadruplex DNA (G4-DNA) is frequently formed in the promoter regions of oncogenes and the ends of telomerase genes, considered as promising drug targets for anticancer therapy. There are no reports about TXN A interactions with G4-DNA. Here, we tested TXN A's interactions with several G4-DNA oligos with parallel, antiparallel, or hybrid folding, respectively. We demonstrated that TXN A preferred to alkylate one flexible guanine in the loops of parallel G4-DNA. The position of the alkylated guanine is in favor of interactions of G4-DNA with TXN A. The structure of TXN A covalently bound RET G4-DNA indicated that TXN A alkylation on RET G4-DNA stabilizes the G4-DNA conformation. These studies opened a new window of how TXN A interacted with G4-DNA, which might hint a new mode of its function as an anticancer agent.

RET signaling in breast cancer therapeutic resistance and metastasis

RET, a single-pass receptor tyrosine kinase encoded on human chromosome 10, is well known to the field of developmental biology for its role in the ontogenesis of the central and enteric nervous systems and the kidney. In adults, RET alterations have been characterized as drivers of non-small cell lung cancer and multiple neuroendocrine neoplasms. In breast cancer, RET signaling networks have been shown to influence diverse functions including tumor development, metastasis, and therapeutic resistance. While RET is known to drive the development and progression of multiple solid tumors, therapeutic agents selectively targeting RET are relatively new, though multiple multi-kinase inhibitors have shown promise as RET inhibitors in the past; further, RET has been historically neglected as a potential therapeutic co-target in endocrine-refractory breast cancers despite mounting evidence for a key pathologic role and repeated description of a bi-directional relationship with the estrogen receptor, the principal driver of most breast tumors. Additionally, the recent discovery of RET enrichment in breast cancer brain metastases suggests a role for RET inhibition specific to advanced disease. This review assesses the status of research on RET in breast cancer and evaluates the therapeutic potential of RET-selective kinase inhibitors across major breast cancer subtypes.

RET signaling pathway and RET inhibitors in human cancer

Rearranged during transfection (RET) receptor tyrosine kinase was first identified over thirty years ago as a novel transforming gene. Since its discovery and subsequent pathway characterization, RET alterations have been identified in numerous cancer types and are most prevalent in thyroid carcinomas and non-small cell lung cancer (NSCLC). In other tumor types such as breast cancer and salivary gland carcinomas, RET alterations can be found at lower frequencies. Aberrant RET activity is associated with poor prognosis of thyroid and lung carcinoma patients, and is strongly correlated with increased risk of distant metastases. RET aberrations encompass a variety of genomic or proteomic alterations, most of which confer constitutive activation of RET. Activating RET alterations, such as point mutations or gene fusions, enhance activity of signaling pathways downstream of RET, namely PI3K/AKT, RAS/RAF, MAPK, and PLCγ pathways, to promote cell proliferation, growth, and survival. Given the important role that mutant RET plays in metastatic cancers, significant efforts have been made in developing inhibitors against RET kinase activity. These efforts have led to FDA approval of Selpercatinib and Pralsetinib for NSCLC, as well as, additional selective RET inhibitors in preclinical and clinical testing. This review covers the current biological understanding of RET signaling, the impact of RET hyperactivity on tumor progression in multiple tumor types, and RET inhibitors with promising preclinical and clinical efficacy.

Comprehensive immunohistochemical analysis of RET, BCAR1, and BCAR3 expression in patients with Luminal A and B breast cancer subtypes

PURPOSE

Breast cancer (BC) is considered a heterogeneous disease composed of distinct subtypes with diverse clinical outcomes. Luminal subtype tumors have the best prognosis, and patients benefit from endocrine therapy. However, resistance to endocrine therapies in BC is an obstacle to successful treatment, and novel biomarkers are needed to understand and overcome this mechanism. The RET, BCAR1, and BCAR3 genes may be associated with BC progression and endocrine resistance.

METHODS

Aiming to evaluate the expression profile and prognostic value of RET, BCAR1, and BCAR3, we performed immunohistochemistry on tissue microarrays (TMAs) containing a cohort of 361 Luminal subtype BC.

RESULTS

Low expression levels of these three proteins were predominantly observed. BCAR1 expression was correlated with nuclear grade (p = 0.057), and BCAR3 expression was correlated with lymph node status (p = 0.011) and response to hormonal therapy (p = 0.021). Further, low expression of either BCAR1 or BCAR3 was significantly associated with poor prognosis (p = 0.005; p = 0.042). Pairwise analysis showed that patients with tumors with low BCAR1/low BCAR3 expression had a poorer overall survival (p = 0.013), and the low BCAR3 expression had the worst prognosis with RET high expression stratifying these patients into two different groups. Regarding the response to hormonal therapy, non-responder patients presented lower expression of RET in comparison to the responder group (p = 0.035). Additionally, the low BCAR1 expression patients had poorer outcomes than BCAR1 high (p = 0.015).

CONCLUSION

Our findings suggest RET, BCAR1, and BCAR3 as potential candidate markers for endocrine therapy resistance in Luminal BC.

Deficiency of GFRα1 promotes hepatocellular carcinoma progression but enhances oxaliplatin-mediated anti-tumor efficacy

Neurotrophic factors and their receptors have been identified to promote tumor progression. GFRα1, the receptor for glial cell line-derived neurotrophic factor (GDNF), has been demonstrated to be predominantly expressed in adult liver tissue. Our preliminary data showed that GFRα1 is significantly downregulated in hepatocellular carcinoma (HCC) tissue, compared to the matched non-neoplastic tissue. However, the role of GFRα1 in HCC progression remains unknown. Here we found that the expression of GFRα1 in HCC tissue is inversely correlated with the poorer prognosis of HCC patients. Silencing of GFRα1 expression markedly enhances HCC cell growth, tumor metastasis, as well as shortens the survival of HCC tumor-bearing mice. Forced expression of GFRα1 in HCC cells significantly reverses the tumor-promoting effects of GFRα1 silencing, and AAV8-mediated GFRα1 transfection in HCC tumor tissues significantly impedes tumor growth and prolongs the survival of HCC tumor-bearing mice. These results are also verified in vivo in GFRα1 knock-out mice model, with increased DEN-induced HCC carcinogenesis. Mechanistically, GFRα1 could inhibit epithelial-to-mesenchymal transition (EMT) of HCC cells, by upregulating expression of Claudin-1 and ZO-1. Of note, silencing of GFRα1 expression promotes oxaliplatin-mediated HCC cell apoptosis resulting in prolonged survival of HCC-bearing mice, and forced expression of GFRα1 markedly increased oxaliplatin resistance of HCC cells. These results demonstrate that deficiency of GFRα1 promotes HCC progression but enhances chemotherapeutic anti-tumor efficacy, suggesting that GFRα1 may be a candidate prognostic biomarker and a potential therapeutic target in HCC.

Blood Vessels and Peripheral Nerves as Key Players in Cancer Progression and Therapy Resistance

Simple Summary

The interactions between cancer cells and the surrounding blood vessels and peripheral nerves are critical in all the phases of tumor development. Accordingly, therapies that specifically target vessels and nerves represent promising anticancer approaches. The first aim of this review is to document the importance of blood vessels and peripheral nerves in both cancer onset and local or distant growth of tumoral cells. We then focus on the state-of-the-art therapies that limit cancer progression through the impairment of blood vessels and peripheral nerves. The mentioned literature is helpful for the scientific community to appreciate the recent advances in these two fundamental components of tumors.

Abstract

Cancer cells continuously interact with the tumor microenvironment (TME), a heterogeneous milieu that surrounds the tumor mass and impinges on its phenotype. Among the components of the TME, blood vessels and peripheral nerves have been extensively studied in recent years for their prominent role in tumor development from tumor initiation. Cancer cells were shown to actively promote their own vascularization and innervation through the processes of angiogenesis and axonogenesis. Indeed, sprouting vessels and axons deliver several factors needed by cancer cells to survive and proliferate, including nutrients, oxygen, and growth signals, to the expanding tumor mass. Nerves and vessels are also fundamental for the process of metastatic spreading, as they provide both the pro-metastatic signals to the tumor and the scaffold through which cancer cells can reach distant organs. Not surprisingly, continuously growing attention is devoted to the development of therapies specifically targeting these structures, with promising initial results. In this review, we summarize the latest evidence that supports the importance of blood vessels and peripheral nerves in cancer pathogenesis, therapy resistance, and innovative treatments.

Radiotherapy and immunotherapy converge on elimination of tumor-promoting erythroid progenitor cells through adaptive immunity

Tumor-induced CD45^-Ter119⁺CD71⁺ erythroid progenitor cells, termed "Ter cells," promote tumor progression by secreting artemin (ARTN), a neurotrophic peptide that activates REarranged during Transfection (RET) signaling. We demonstrate that both local tumor ionizing radiation (IR) and anti-programmed death ligand 1 (PD-L1) treatment decreased tumor-induced Ter cell abundance in the mouse spleen and ARTN secretion outside the irradiation field in an interferon- and CD8⁺ T cell-dependent manner. Recombinant erythropoietin promoted resistance to radiotherapy or anti-PD-L1 therapies by restoring Ter cell numbers and serum ARTN concentration. Blockade of ARTN or potential ARTN signaling partners, or depletion of Ter cells augmented the antitumor effects of both IR and anti-PD-L1 therapies in mice. Analysis of samples from patients who received radioimmunotherapy demonstrated that IR-mediated reduction of Ter cells, ARTN, and GFRα3, an ARTN signaling partner, were each associated with tumor regression. Patients with melanoma who received immunotherapy exhibited favorable outcomes associated with decreased expression of GFRα3. These findings demonstrate an out-of-field, or "abscopal," effect mediated by adaptive immunity, which is induced during local tumor irradiation. This effect, in turn, governs the therapeutic effects of radiation and immunotherapy. Therefore, our results identify multiple targets to potentially improve outcomes after radiotherapy and immunotherapy.

Mini-review: Trophic interactions between cancer cells and primary afferent neurons

Cancer neurobiology is an emerging discipline that inevitably unfurls new perspectives in oncology. The role that nerves play in cancer progression resonates with the long-reported dependency of tumors on neuro-molecular mechanisms that remain insufficiently elucidated. Whereas interactions between neurotrophic growth factors and receptors have been heavily studied in the nervous system, their expression in cancers and their impact on tumor cell growth and metastasis through their corresponding signaling pathways has been undervalued. Accumulating evidence suggests that trophic factors released by nerves strongly influence tumor development and that this neural contribution appears to not only play a stimulatory role but also function as an essential part of the tumor's microenvironment. This bidirectional communication between proliferating cells and tumor-infiltrating nerves drives axonogenesis and tumor growth and migration. Acquiring a better understanding of the trophic interactions between primary afferent neurons and invading tumors will guide clinically actionable strategies to prevent tumor-associated axonogenesis, disrupting the chemical crosstalk between neurons and tumors and ultimately decreasing tumor growth and spread.

Overexpression of GDNF and FGF-1 in Canine Benign Prostatic Hyperplasia: Evidence for a Pathogenetic Role of Neural Growth Factor

Benign prostatic hyperplasia (BPH) is common in aged dogs, but the pathogenesis has not been clearly elucidated. A total of 33 male Iranian dogs of mixed breed and in three age groups (under 3 years [n = 10]; 3-6 years [n = 15]; over 6 years [n = 8]), were investigated. BPH was confirmed by ultrasonography and histopathology in 13 cases. The highest prevalence of BPH was in the 3-6 years age group (8/15; 53.3%). Examination of sections of prostate that had been stained with Masson's trichrome revealed that the intensity of stromal smooth muscle cell staining (P <0.05) and the number of fibroblasts (P = 0.002) were significantly increased in BPH compared with normal prostate glands. Prostate cells from dogs with BPH (n = 13) had a significantly higher intensity of cytoplasmic immunolabelling with antibodies against glial cell line-derived neurotrophic factor (GDNF), cytokeratin (CK) AE1/AE3, vimentin, fibroblast growth factor-1 (FGF-1) and prostate-specific antigen (PSA), compared with normal prostate glands (n = 20) (P = 0.001), except for PSA, which was negative in both normal and BPH affected prostates. The overexpression of GDNF and FGF-1 in stromal and epithelial cells of prostate glands of dogs with BPH suggests that GDNF has a paracrine or autocrine role in stimulating cellular proliferation. GDNF overexpression may also play a pathogenetic role in promoting chronic prostatitis and increasing fibrosis and the smooth muscle component of the prostate gland in BPH.

Generation of an Oncolytic Herpes Simplex Viral Vector Completely Retargeted to the GDNF Receptor GFRα1 for Specific Infection of Breast Cancer Cells

Oncolytic herpes simplex viruses (oHSV) are under development for the treatment of a variety of human cancers, including breast cancer, a leading cause of cancer mortality among women worldwide. Here we report the design of a fully retargeted oHSV for preferential infection of breast cancer cells through virus recognition of GFRα1, the cellular receptor for glial cell-derived neurotrophic factor (GDNF). GFRα1 displays a limited expression profile in normal adult tissue, but is upregulated in a subset of breast cancers. We generated a recombinant HSV expressing a completely retargeted glycoprotein D (gD), the viral attachment/entry protein, that incorporates pre-pro-GDNF in place of the signal peptide and HVEM binding domain of gD and contains a deletion of amino acid 38 to eliminate nectin-1 binding. We show that GFRα1 is necessary and sufficient for infection by the purified recombinant virus. Moreover, this virus enters and spreads in GFRα1-positive breast cancer cells in vitro and caused tumor regression upon intratumoral injection in vivo. Given the heterogeneity observed between and within individual breast cancers at the molecular level, these results expand our ability to deliver oHSV to specific tumors and suggest opportunities to enhance drug or viral treatments aimed at other receptors.

Hypomethylation of GDNF family receptor alpha 1 promotes epithelial-mesenchymal transition and predicts metastasis of colorectal cancer

Tumor metastasis is the major cause of poor prognosis and mortality in colorectal cancer (CRC). However, early diagnosis of highly metastatic CRC is currently difficult. In the present study, we screened for a novel biomarker, GDNF family receptor alpha 1 (GFRA1) based on the expression and methylation data in CRC patients from The Cancer Genome Altlas (TCGA), followed by further analysis of the correlation between the GFRA1 expression, methylation, and prognosis of patients. Our results show DNA hypomethylation-mediated upregulation of GFRA1 in invasive CRC, and it was found to be correlated with poor prognosis of CRC patients. Furthermore, GFRA1 methylation-modified sequences were found to have potential as methylation diagnostic markers of highly metastatic CRC. The targeted demethylation of GFRA1 by dCas9-TET1CD and gRNA promoted CRC metastasis in vivo and in vitro. Mechanistically, demethylation of GFRA1 induces epithelial-mesenchymal transition (EMT) by promoting AKT phosphorylation and increasing c-Jun expression in CRC cells. Collectively, our findings indicate that GFRA1 hypomethylation can promote CRC invasion via inducing EMT, and thus, GFRA1 methylation can be used as a biomarker for the early diagnosis of highly metastasis CRC.

RET Receptor Tyrosine Kinase: Role in Neurodegeneration, Obesity, and Cancer

Rearranged during transfection (RET) is the tyrosine kinase receptor that under normal circumstances interacts with ligand at the cell surface and mediates various essential roles in a variety of cellular processes such as proliferation, differentiation, survival, migration, and metabolism. RET plays a pivotal role in the development of both peripheral and central nervous systems. RET is expressed from early stages of embryogenesis and remains expressed throughout all life stages. Mutations either activating or inhibiting RET result in several aggressive diseases, namely cancer and Hirschsprung disease. However, the physiological ligand-dependent activation of RET receptor is important for the survival and maintenance of several neuronal populations, appetite, and weight gain control, thus providing an opportunity for the development of disease-modifying therapeutics against neurodegeneration and obesity. In this review, we describe the structure of RET, its signaling, and its role in both normal conditions as well as in several disorders. We highlight the differences in the signaling and outcomes of constitutive and ligand-induced RET activation. Finally, we review the data on recently developed small molecular weight RET agonists and their potential for the treatment of various diseases.

RET isoforms contribute differentially to invasive processes in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a therapeutically challenging disease with poor survival rates, owing to late diagnosis and early dissemination. These tumors frequently undergo perineural invasion, spreading along nerves regionally and to distant sites. The RET receptor tyrosine kinase is implicated in increased aggressiveness, local invasion, and metastasis in multiple cancers, including PDAC. RET mediates directional motility and invasion towards sources of its neurotrophic factor ligands, suggesting that it may enhance perineural invasion of tumor cells towards nerves. RET is expressed as two main isoforms, RET9 and RET51, which differ in their protein interactions and oncogenic potentials, however, the contributions of RET isoforms to neural invasion have not been investigated. In this study, we generated total RET and isoform-specific knockdown PDAC cell lines and assessed the contributions of RET isoforms to PDAC invasive spread. Our data show that RET activity induces cell polarization and actin remodeling through activation of CDC42 and RHOA GTPases to promote directional motility in PDAC cells. Further, we show that RET interacts with the adaptor protein TKS5 to induce invadopodia formation, enhance matrix degradation and promote tumor cell invasion through a SRC and GRB2-dependent mechanism. Finally, we show that RET51 is the predominant isoform contributing to these RET-mediated invasive processes in PDAC. Together, our work suggests that RET expression in pancreatic cancers may enhance tumor aggressiveness by promoting perineural invasion, and that RET expression may be a valuable marker of invasiveness, and a potential therapeutic target in the treatment of these cancers.

Glial-derived neurotrophic factor regulates enteric mast cells and ameliorates dextran sulfate sodium-induced experimental colitis

BACKGROUND & AIMS

Although interactions between enteric glial cells (EGCs) and enteric mast cells have been demonstrated to play an important role in the pathogenesis of inflammatory bowel disease (IBD), the exact mechanisms by which EGCs regulate enteric mast cells are still unknown. The aims of this study were to investigate whether glial-derived neurotrophic factor (GDNF), which has been confirmed to be produced mostly by EGCs, might regulate enteric mast cells and ameliorate dextran sulfate sodium (DSS)-induced experimental colitis.

METHODS

Recombinant adenoviral vectors encoding GDNF (Ad-GDNF) were administered intracolonically in experimental colitis induced by DSS. The disease activity index and histological score were measured. The expression of tumour necrosis factor-α (TNF-α), interleukin-6 and myeloperoxidase (MPO) activity were measured by ELISA assay. The expression of trypsin and β-hexosaminidase were evaluated. GDNF specific receptor (GFR-α1/RET) was detected. The calcium reflux was tested by microplate reader. The expression p-JNK was analyzed by western blot assay.

RESULTS

GDNF resulted in a significant inhibition of the activation of enteric mast cells by down-regulating JNK signal pathway, lessening intracellular calcium influx, and then reducing the degranulation as well as the expression of pro-inflammatory cytokines via combing with its receptor (GFR-α1/RET) in mast cells, and these inhibitory effects were abrogated by treatment with neutralizing antibody against GDNF. Moreover, the administration of GDNF led to an amelioration of experimental colitis.

CONCLUSIONS

GDNF are able to regulate enteric mast cells and ameliorate experimental colitis. GDNF might be an important mediator of the cross-talk between EGCs and enteric mast cells, and GDNF might be a useful therapeutic drug for IBD.

Revisiting the Role of Neurotrophic Factors in Inflammation

The neurotrophic factors are well known for their implication in the growth and the survival of the central, sensory, enteric and parasympathetic nervous systems. Due to these properties, neurturin (NRTN) and Glial cell-derived neurotrophic factor (GDNF), which belong to the GDNF family ligands (GFLs), have been assessed in clinical trials as a treatment for neurodegenerative diseases like Parkinson’s disease. In addition, studies in favor of a functional role for GFLs outside the nervous system are accumulating. Thus, GFLs are present in several peripheral tissues, including digestive, respiratory, hematopoietic and urogenital systems, heart, blood, muscles and skin. More precisely, recent data have highlighted that different types of immune and epithelial cells (macrophages, T cells, such as, for example, mucosal-associated invariant T (MAIT) cells, innate lymphoid cells (ILC) 3, dendritic cells, mast cells, monocytes, bronchial epithelial cells, keratinocytes) have the capacity to release GFLs and express their receptors, leading to the participation in the repair of epithelial barrier damage after inflammation. Some of these mechanisms pass on to ILCs to produce cytokines (such as IL-22) that can impact gut microbiota. In addition, there are indications that NRTN could be used in the treatment of inflammatory airway diseases and it prevents the development of hyperglycemia in the diabetic rat model. On the other hand, it is suspected that the dysregulation of GFLs produces oncogenic effects. This review proposes the discussion of the biological understanding and the potential new opportunities of the GFLs, in the perspective of developing new treatments within a broad range of human diseases.

Ret Receptor Has Distinct Alterations and Functions in Breast Cancer

Ret receptor tyrosine kinase is a proto-oncogene that participates in development of various cancers. Several independent studies have recently identified Ret as a key player in breast cancer. Although Ret overexpression and function have been under investigation, mainly in estrogen receptor positive breast cancer, a more comprehensive analysis of the impact of recurring Ret alterations in breast cancer is needed. This review consolidates the current knowledge of Ret alterations and their potential effects in breast cancer. We discuss and integrate data on Ret changes in different breast cancer subtypes and potential function in progression, as well as the participation of distinct Ret network signaling partners in these processes. We propose that it will be essential to define a shared molecular feature of tumors with alteration in Ret receptor, be this at the genetic level or via overexpression in order to design effective therapies to target the Ret pathway. Here we review experimental evidence from basic research and pre-clinical studies concentrating on Ret alterations as potential biomarkers for recurrence, and we discuss the possibility that targeting the Ret pathway might in the future become a treatment for breast cancer.

Colchicine selective interaction with oncogene RET G-quadruplex revealed by NMR

G-quadruplexes (G4s) are frequently formed in the promoter regions of oncogenes, considered as promising drug targets for anticancer therapy. Due to high structure similarity of G4s, discovering ligands selectively interacting with only one G4 is extremely difficult. Here, mainly by NMR, we report that colchicine selectively binds to oncogene RET G4-DNA.

RET fusions in solid tumors

The RET proto-oncogene has been well-studied. RET is involved in many different physiological and developmental functions. When altered, RET mutations influence disease in a variety of organ systems from Hirschsprung's disease and multiple endocrine neoplasia 2 (MEN2) to papillary thyroid carcinoma (PTC) and non-small cell lung cancer (NSCLC). Changes in RET expression have been discovered in 30-70% of invasive breast cancers and 50-60% of pancreatic ductal adenocarcinomas in addition to colorectal adenocarcinoma, melanoma, small cell lung cancer, neuroblastoma, and small intestine neuroendocrine tumors. RET mutations have been associated with tumor proliferation, invasion, and migration. RET fusions or rearrangements are somatic juxtapositions of 5' sequences from other genes with 3' RET sequences encoding tyrosine kinase. RET rearrangements occur in approximately 2.5-73% of sporadic PTC and 1-3% of NSCLC patients. The most common RET fusions are CDCC6-RET and NCOA4-RET in PTC and KIF5B-RET in NSCLC. Tyrosine kinase inhibitors are drugs that target kinases such as RET in RET-driven (RET-mutation or RET-fusion-positive) disease. Multikinase inhibitors (MKI) target various kinases and other receptors. Several MKIs are FDA-approved for cancer therapy (sunitinib, sorafenib, vandetanib, cabozantinib, regorafenib, ponatinib, lenvatinib, alectinib) and non-oncologic disease (nintedanib). Selective RET inhibitor drugs LOXO-292 (selpercatinib) and BLU-667 (pralsetinib) are also undergoing phase I/II and I clinical trials, respectively, with preliminary results demonstrating partial response and low incidence of serious adverse events. RET fusions provide a viable therapeutic target for oncologic treatment, and further study is warranted into the prevalence and pathogenesis of RET fusions as well as development of current and new tyrosine kinase inhibitors.

A panel of DNA methylated markers predicts metastasis of pN0M0 gastric carcinoma: a prospective cohort study

BACKGROUND

The aim of this prospective study was to evaluate the feasibility of predicting GC metastasis using CDH1, GFRA1, P16 and ZNF382 DNA methylation as biomarkers.

METHODS

198 GC patients without metastasis at the time of surgery resection were recruited into the double-blind cohort (NCT02159339). Gene methylation was analysed using MethyLight assays. GC metastasis and survival data were obtained from 178 patients with 94.7% compliance during follow-up.

RESULTS

Twenty six cases of metastasis and 5 cases of recurrence were observed in 178 cases (17.4%) during the follow-up (median, 62.7 months). The GC metastasis rate for GFRA1 methylation-positive patients was significantly reduced compared with GFRA1 methylation-negative patients (odds ratio [OR]: 0.23, 95% confidence interval [CI] 0.08-0.66). Similar results were also observed using ZNF382 methylation as a predictor (OR: 0.17, 95% CI 0.06-0.47). A risk score including methylation of GFRA1 and ZNF382 was generated. The metastasis rate was significantly increased in high-risk GC patients (OR: 4.71, 95% CI: 1.85-12.00). GC patients with high risk had a shorter overall survival, especially for patients with stage I GC (P = 0.024).

CONCLUSIONS

The combination of GFRA1 and ZNF382 methylation is a biomarker panel for the prediction of GC metastasis.

Expression of RET is associated with Oestrogen receptor expression but lacks prognostic significance in breast cancer

BACKGROUND

The Rearranged during Transfection (RET) protein is overexpressed in a subset of Estrogen Receptor (ER) positive breast cancer, with both signalling pathways functionally interacting. This cross-talk plays a pivotal role in the resistance of breast cancer cells to anti-endocrine therapies, and RET expression is assumed to correlate with poor prognosis based on findings in small patient cohorts. The aim of our study was to investigate the impact of RET expression on patient outcome in human breast cancer.

METHODS

We performed an immunohistochemical analysis of RET protein expression on a tissue microarray encompassing 990 breast cancer patients and correlated its expression with clinicopathological parameters and survival data.

RESULTS

Expression of RET was detected in 409 out of 990 cases (41.3%). RET and ER expression significantly correlated (p < 0.0001). The Luminal B HER2-positive subtype showed the highest expression rate (48.9%). In univariate and multivariate survival analyses, RET expression had no impact on overall survival.

CONCLUSION

We confirmed the co-expression of RET and ER, but we did not find RET expression to be an independent prognostic factor in human breast cancer. Clinical trials with newly developed RET inhibitors are needed to evaluate if RET inhibition has a beneficial impact on patient survival in ER positive breast cancer.

GDNF and the RET Receptor in Cancer: New Insights and Therapeutic Potential

The Glial cell line-derived neurotrophic Family Ligands (GFL) are soluble neurotrophic factors that are required for development of multiple human tissues, but which are also important contributors to human cancers. GFL signaling occurs through the transmembrane RET receptor tyrosine kinase, a well-characterized oncogene. GFL-independent RET activation, through rearrangement or point mutations occurs in thyroid and lung cancers. However, GFL-mediated activation of wildtype RET is an increasingly recognized mechanism promoting tumor growth and dissemination of a much broader group of cancers. RET and GFL expression have been implicated in metastasis or invasion in diverse human cancers including breast, pancreatic, and prostate tumors, where they are linked to poorer patient prognosis. In addition to directly inducing tumor growth in these diseases, GFL-RET signaling promotes changes in the tumor microenvironment that alter the surrounding stroma and cellular composition to enhance tumor invasion and metastasis. As such, GFL RET signaling is an important target for novel therapeutic approaches to limit tumor growth and spread and improve disease outcomes.

Competing endogenous RNA (ceRNA) cross talk and language in ceRNA regulatory networks: A new look at hallmarks of breast cancer

Breast cancer (BC) is the most frequently occurring malignancy in women worldwide. Despite the substantial advancement in understanding the molecular mechanisms and management of BC, it remains the leading cause of cancer death in women. One of the main reasons for this obstacle is that we have not been able to find the Achilles heel for the BC as a highly heterogeneous disease. Accumulating evidence has revealed that noncoding RNAs (ncRNAs), play key roles in the development of BC; however, the involving of complex regulatory interactions between the different varieties of ncRNAs in the development of this cancer has been poorly understood. In the recent years, the newly discovered mechanism in the RNA world is "competing endogenous RNA (ceRNA)" which proposes regulatory dialogues between different RNAs, including long ncRNAs (lncRNAs), microRNAs (miRNAs), transcribed pseudogenes, and circular RNAs (circRNAs). In the latest BC research, various studies have revealed that dysregulation of several ceRNA networks (ceRNETs) between these ncRNAs has fundamental roles in establishing the hallmarks of BC development. And it is thought that such a discovery could open a new window for a better understanding of the hidden aspects of breast tumors. Besides, it probably can provide new biomarkers and potential efficient therapeutic targets for BC. This review will discuss the existing body of knowledge regarding the key functions of ceRNETs and then highlights the emerging roles of some recently discovered ceRNETs in several hallmarks of BC. Moreover, we propose for the first time the "ceRnome" as a new term in the present article for RNA research.

RET rearrangements are actionable alterations in breast cancer

Fusions involving the oncogenic gene RET have been observed in thyroid and lung cancers. Here we report RET gene alterations, including amplification, missense mutations, known fusions, novel fusions, and rearrangements in breast cancer. Their frequency, oncogenic potential, and actionability in breast cancer are described. Two out of eight RET fusions (NCOA4-RET and a novel RASGEF1A-RET fusion) and RET amplification were functionally characterized and shown to activate RET kinase and drive signaling through MAPK and PI3K pathways. These fusions and RET amplification can induce transformation of non-tumorigenic cells, support xenograft tumor formation, and render sensitivity to RET inhibition. An index case of metastatic breast cancer progressing on HER2-targeted therapy was found to have the NCOA4-RET fusion. Subsequent treatment with the RET inhibitor cabozantinib led to a rapid clinical and radiographic response. RET alterations, identified by genomic profiling, are promising therapeutic targets and are present in a subset of breast cancers.

Fusions of the gene RET have been described in thyroid and lung cancers. Here, the AUs identify RET gene alterations, including known fusions, novel fusions, and rearrangements in breast cancer (BC) that are involved in the tumorigenic process and show the benefit of RET therapy in a recurrent BC patient carrying the NCOA4-RET fusion.

Reciprocal feedback regulation of ST3GAL1 and GFRA1 signaling in breast cancer cells

GFRA1 and RET are overexpressed in estrogen receptor (ER)-positive breast cancers. Binding of GDNF to GFRA1 triggers RET signaling leading to ER phosphorylation and estrogen-independent transcriptional activation of ER-dependent genes. Both GFRA1 and RET are membrane proteins which are N-glycosylated but no O-linked sialylation site on GFRA1 or RET has been reported. We found GFRA1 to be a substrate of ST3GAL1-mediated O-linked sialylation, which is crucial to GDNF-induced signaling in ER-positive breast cancer cells. Silencing ST3GAL1 in breast cancer cells reduced GDNF-induced phosphorylation of RET, AKT and ERα, as well as GDNF-mediated cell proliferation. Moreover, GDNF induced transcription of ST3GAL1, revealing a positive feedback loop regulating ST3GAL1 and GDNF/GFRA1/RET signaling in breast cancers. Finally, we demonstrated ST3GAL1 knockdown augments anti-cancer efficacy of inhibitors of RET and/or ER. Moreover, high expression of ST3GAL1 was associated with poor clinical outcome in patients with late stage breast cancer and high expression of both ST3GAL1 and GFRA1 adversely impacted outcome in those with high grade tumors.

Discordance of the PAM50 Intrinsic Subtypes Compared with Immunohistochemistry-Based Surrogate in Breast Cancer Patients: Potential Implication of Genomic Alterations of Discordance

Purpose

We aimed to analyze the discordance between immunohistochemistry (IHC)-based surrogate subtyping and PAM50 intrinsic subtypes and to assess overall survival (OS) according to discordance.

Materials and Methods

A total of 607 patients were analyzed. Hormone receptor (HR) expression was evaluated by IHC, and human epidermal growth factor receptor 2 (HER2) expression was analyzed by IHC and/or fluorescence in situ hybridization. PAM50 intrinsic subtypes were determined according to 50 cancer genes using the NanoString nCounter Analysis System. We matched concordant tumor as luminal A and HR+/HER2–, luminal B and HR+/HER2+, HR–/HER2+ and HER2–enriched, and triple-negative breast cancer (TNBC) and normal- or basal-like. We used Ion Ampliseq Cancer Panel v2 was used to identify the genomic alteration related with discordance. The Kaplan-Meier method was used to estimate OS.

Results

In total, 233 patients (38.4%) were discordant between IHC-based subtype and PAM50 intrinsic subtype. Using targeted sequencing, we detected somatic mutation–related discordant breast cancer including the VHL gene in the HR+/HER2– group (31% in concordant group, 0% in discordant group, p=0.03) and the IDH and RET genes (7% vs. 12%, p=0.02 and 0% vs. 25%, p=0.02, respectively) in the TNBC group. Among the luminal A/B patients with a discordant result had significantly worse OS (median OS, 73.6 months vs. not reached; p < 0.001), and among the patients with HR positivity, the basal-like group as determined by PAM50 showed significantly inferior OS compared to other intrinsic subtypes (5-year OS rate, 92.2% vs. 75.6%; p=0.01).

Conclusion

A substantial portion of patients showed discrepancy between IHC subtype and PAM50 intrinsic subtype in our study. The survival analysis demonstrated that current IHC-based classification could mislead the treatment and result in poor outcome. Current guidelines for IHC might be updated accordingly.

Advances in circular RNAs and their roles in breast Cancer

Circular RNAs (circRNAs) are a type of noncoding RNAs with a closed loop structure. With the development of high-throughput sequencing, massive circRNAs have been discovered in tumorous tissues. Emerging evidence suggests that the biological functions of circRNAs including serving as ceRNAs or miRNA sponges, interacting with proteins, regulating gene transcription and translation, suggesting that circRNAs will be novel biomarkers and targets for the diagnosis and prognosis of diseases. Breast cancer is the most frequently occurring cancer and the leading cause of cancer-related death among women worldwide. It is vital to understand the molecular pathways involved in the pathogenesis of proliferation and progression. In this review, we summarize the current knowledge on human circRNAs and their potential clinical implications on breast cancer.

Preclinical evaluation of a GFRA1 targeted antibody-drug conjugate in breast cancer

Despite recent advances in treatment, breast cancer remains the second-most common cause of cancer death among American women. A greater understanding of the molecular characteristics of breast tumors could ultimately lead to improved tumor-targeted treatment options, particularly for subsets of breast cancer patients with unmet needs. Using an unbiased genomics approach to uncover membrane-localized tumor-associated antigens (TAAs), we have identified glial cell line derived neurotrophic factor (GDNF) family receptor α 1 (GFRA1) as a breast cancer TAA. Immunohistochemistry (IHC) revealed that GFRA1 displays a limited normal tissue expression profile coupled with overexpression in specific breast cancer subsets. The cell surface localization as determined by fluorescence-activated cell sorting (FACS) and the rapid internalization kinetics of GFRA1 makes it an ideal target for therapeutic exploitation as an antibody-drug conjugate (ADC). Here, we describe the development of a pyrrolobenzodiazepine (PBD)-armed, GFRA1-targeted ADC that demonstrates cytotoxicity in GFRA1-positive cell lines and patient-derived xenograft (PDX) models. The safety profile of the rat cross-reactive GFRA1-PBD was assessed in a rat toxicology study to find transient cellularity reductions in the bone marrow and peripheral blood, consistent with known off-target effects of PBD ADC's. These studies reveal no evidence of on-target toxicity and support further evaluation of GFRA1-PBD in GFRA1-positive tumors.

Chronic expression of wild-type Ret receptor in the mammary gland induces luminal tumors that are sensitive to Ret inhibition

The receptor tyrosine kinase Ret, a key gain-of-function mutated oncoprotein in thyroid carcinomas, has recently been implicated in other cancer types. While Ret copy number gains and mutations have been reported at low frequencies in breast tumors, we and others have reported that Ret is overexpressed in about 40% of human tumors and this correlates with poor patient prognosis. Ret activation regulates numerous intracellular pathways related to proliferation and inflammation, but it is not known whether abnormal Ret expression is sufficient to induce mammary carcinomas. Using a novel doxycycline-inducible transgenic mouse model with the MMTV promoter controlling Ret expression, we show that overexpression of wild-type Ret in the mammary epithelium produces mammary tumors, displaying a morphology that recapitulates characteristics of human luminal breast tumors. Ret-evoked tumors are estrogen receptor positive and negative for progesterone receptor. Moreover, tumors rapidly regress after doxycycline withdrawal, indicating that Ret is the driving oncoprotein. Using next-generation sequencing, we examined the levels of transcripts in these tumors, confirming a luminal signature. Ret-evoked tumors have been passaged in mice and used to test novel therapeutic approaches. Importantly, we have determined that tumors are resistant to endocrine therapy, but respond successfully to treatment with a Ret kinase inhibitor. Our data provide the first compelling evidence for an oncogenic role of non-mutated Ret in the mammary gland and are an incentive for clinical development of Ret as a cancer biomarker and therapeutic target.

GFRA1: A Novel Molecular Target for the Prevention of Osteosarcoma Chemoresistance

The glycosylphosphatidylinositol-linked GDNF (glial cell derived neurotrophic factor) receptor alpha (GFRA), a coreceptor that recognizes the GDNF family of ligands, has a crucial role in the development and maintenance of the nervous system. Of the four identified GFRA isoforms, GFRA1 specifically recognizes GDNF and is involved in the regulation of proliferation, differentiation, and migration of neuronal cells. GFRA1 has also been implicated in cancer cell progression and metastasis. Recent findings show that GFRA1 can contribute to the development of chemoresistance in osteosarcoma. GFRA1 expression was induced following treatment of osteosarcoma cells with the popular anticancer drug, cisplatin and induction of GFRA1 expression significantly suppressed apoptosis mediated by cisplatin in osteosarcoma cells. GFRA1 expression promotes autophagy by activating the SRC-AMPK signaling axis following cisplatin treatment, resulting in enhanced osteosarcoma cell survival. GFRA1-induced autophagy promoted tumor growth in mouse xenograft models, suggesting a novel function of GFRA1 in osteosarcoma chemoresistance.

ER-positive breast cancer cells are poised for RET-mediated endocrine resistance

The RET tyrosine kinase signaling pathway is involved in the development of endocrine resistant ER+ breast cancer. However, we know little about how ER+ cells activate RET signaling and initiate an endocrine resistant phenotype. Here we show that both ER+ endocrine resistant and sensitive breast cancers have a functional RET tyrosine kinase signaling pathway, but that endocrine sensitive breast cancer cells lack RET ligands that are necessary to drive endocrine resistance. Transcription of one RET ligand, GDNF, is necessary and sufficient to confer resistance in the ER+ MCF-7 cell line. Endogenous GDNF produced by endocrine resistant cells is translated, secreted into the media, and activates RET signaling in nearby cells. In patients, RET ligand expression predicts responsiveness to endocrine therapies and correlates with survival. Collectively, our findings show that ER+ tumor cells are "poised" for RET mediated endocrine resistance, expressing all components of the RET signaling pathway, but endocrine sensitive cells lack high expression of RET ligands that are necessary to initiate the resistance phenotype.

Role of artemin in non-small cell lung cancer

Background

In this study, we investigated the role of artemin, a member of the glial cell‐derived neurotrophic factor of ligands, in the malignant phenotype of lung cancer.

Methods

Artemin expression was examined in various types of lung cancer and normal lung tissues, as well as in lung cancer cell lines by immunohistochemistry and semi‐quantitative PCR. Functional studies were performed using artemin overexpression or knockdown vectors in lung cancer cell lines. Methyl thiazolyl tetrazolium, flow cytometry, wound healing, and transwell assays were conducted to evaluate the contribution of artemin on tumor cell proliferation, migration, and invasion.

Results

Artemin is broadly expressed in lung cancer tissues, and is associated with tumor staging. Overexpression of artemin in NL9980 large cell lung cancer cells increased proliferating cells and enhanced migrating capability in wound healing and transwell assays, as well as demonstrating enhanced invasion capability. Silencing artemin in LTEP‐α‐2 adenocarcinoma cell lines decreased cellular proliferation, migration, and invasion capabilities.

Conclusion

Artemin could promote the proliferation and invasiveness of lung cancer cells in vitro and therefore could be a new potential target to combat lung cancer.

RET-mediated autophagy suppression as targetable co-dependence in acute myeloid leukemia

Many cases of AML are associated with mutational activation of receptor tyrosine kinases (RTKs) such as FLT3. However, RTK inhibitors have limited clinical efficacy as single agents, indicating that AML is driven by concomitant activation of different signaling molecules. We used a functional genomic approach to identify RET, encoding an RTK, as an essential gene in multiple subtypes of AML, and observed that AML cells show activation of RET signaling via ARTN/GFRA3 and NRTN/GFRA2 ligand/co-receptor complexes. Interrogation of downstream pathways identified mTORC1-mediated suppression of autophagy and subsequent stabilization of leukemogenic drivers such as mutant FLT3 as important RET effectors. Accordingly, genetic or pharmacologic RET inhibition impaired the growth of FLT3-dependent AML cell lines and was accompanied by upregulation of autophagy and FLT3 depletion. RET dependence was also evident in mouse models of AML and primary AML patient samples, and transcriptome and immunohistochemistry analyses identified elevated RET mRNA levels and co-expression of RET and FLT3 proteins in a substantial proportion of AML patients. Our results indicate that RET-mTORC1 signaling promotes AML through autophagy suppression, suggesting that targeting RET or, more broadly, depletion of leukemogenic drivers via autophagy induction provides a therapeutic opportunity in a relevant subset of AML patients.

EGFR mediates activation of RET in lung adenocarcinoma with neuroendocrine differentiation characterized by ASCL1 expression

Achaete-scute homolog 1 (ASCL1) is a neuroendocrine transcription factor specifically expressed in 10-20% of lung adenocarcinomas (AD) with neuroendocrine (NE) differentiation (NED). ASCL1 functions as an upstream regulator of the RET oncogene in AD with high ASCL1 expression (A⁺AD). RET is a receptor tyrosine kinase with two main human isoforms; RET9 (short) and RET51 (long). We found that elevated expression of RET51 associated mRNA was highly predictive of poor survival in stage-1 A⁺AD (p=0.0057). Functional studies highlighted the role of RET in promoting invasive properties of A⁺AD cells. Further, A⁺AD cells demonstrated close to 10 fold more sensitivity to epidermal growth factor receptor (EGFR) inhibitors, including gefitinib, than AD cells with low ASCL1 expression. Treatment with EGF robustly induced phosphorylation of RET at Tyr-905 in A⁺AD cells with wild type EGFR. This phosphorylation was blocked by gefitinib and by siRNA-EGFR. Immunoprecipitation experiments found EGFR in a complex with RET in the presence of EGF and suggested that RET51 was the predominant RET isoform in the complex. In the microarray datasets of stage-1 and all stages of A⁺AD, high levels of EGFR and RET RNA were significantly associated with poor overall survival (p < 0.01 in both analyses). These results implicate EGFR as a key regulator of RET activation in A⁺AD and suggest that EGFR inhibitors may be therapeutic in patients with A⁺AD tumors even in the absence of an EGFR or RET mutation.

The serum protein profile of early parity which induces protection against breast cancer

Early parity reduces the risk of breast cancer in women while nulliparity and late parity increase the risk of breast cancer. In order to translate this protection to women where early pregnancy is not feasible, much work has focused on understanding how parity confers protection against breast cancer, the molecular mechanisms by which this occurs is still not well understood. Healthy parous and nulliparous women were recruited for this study. We assessed serum protein profiles of early parous, late parous, and nulliparous women using the Phospho Explorer antibody array. Significantly altered proteins identified were validated by Western blot analysis. In silico analysis was performed with the data obtained. Our findings indicate increased phosphorylation levels of CDK1, AKT1 and Epo-R increased cell cycle and cell proliferation in late/nulliparous women. Increased levels of LIMK1, paxillin, caveolin-1, and tyrosine hydroxylase in late/nulliparous women demonstrate enhanced cell stress while decreased activity of p-p53 and pRAD51 in late/nulliparous women indicates decreased apoptosis and increased genomic instability. Further, increased levels of pFAK, pCD3zeta, pSTAT5B, MAP3K8 in early parous women favor enhanced innate/adaptive immunity. Overall, we have identified a unique protein signature that is responsible for the decreased risk of breast cancer and these proteins can also serve as biomarkers to predict the risk of breast cancer.