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Extracellular vesicles (EVs) are of great interest to study the cellular mechanisms of cancer development and to diagnose and monitor cancer progression. EVs are a highly heterogeneous population of cell derived particles, which include microvesicles (MVs) and exosomes (EXOs). EVs deliver intercellular messages transferring proteins, lipids, nucleic acids, and metabolites with implications for tumour progression, invasiveness, and metastasis. Epidermal Growth Factor Receptor (EGFR) is a major driver of cancer. Tumour cells with activated EGFR could produce EVs disseminating EGFR itself or its ligands. This review provides an overview of EVs (mainly EXOs and MVs) and their cargo, with a subsequent focus on their production and effects related to EGFR activation. In particular, in vitro studies performed in EGFR-dependent solid tumours and/or cell cultures will be explored, thus shedding light on the interplay between EGFR and EVs production in promoting cancer progression, metastases, and resistance to therapies. Finally, an overview of liquid biopsy approaches involving EGFR and EVs in the blood/plasma of EGFR-dependent tumour patients will also be discussed to evaluate their possible application as candidate biomarkers.

Anticancer therapies have been limited by the emergence of mutations and other adaptations. In bacteria, antibiotics activate the SOS response, which mobilizes error-prone factors that allow for continuous replication at the cost of mutagenesis. We investigated whether the treatment of lung cancer with EGFR inhibitors (EGFRi) similarly engages hypermutators. In cycling drug-tolerant persister (DTP) cells and in EGFRi-treated patients presenting residual disease, we observed upregulation of GAS6, whereas ablation of GAS6's receptor, AXL, eradicated resistance. Reciprocally, AXL overexpression enhanced DTP survival and accelerated the emergence of T790M, an EGFR mutation typical to resistant cells. Mechanistically, AXL induces low-fidelity DNA polymerases and activates their organizer, RAD18, by promoting neddylation. Metabolomics uncovered another hypermutator, AXL-driven activation of MYC, and increased purine synthesis that is unbalanced by pyrimidines. Aligning anti-AXL combination treatments with the transition from DTPs to resistant cells cured patient-derived xenografts. Hence, similar to bacteria, tumors tolerate therapy by engaging pharmacologically targetable endogenous mutators.Significance:EGFR-mutant lung cancers treated with kinase inhibitors often evolve resistance due to secondary mutations. We report that in similarity to the bacterial SOS response stimulated by antibiotics, endogenous mutators are activated in drug-treated cells, and this heralds tolerance. Blocking the process prevented resistance in xenograft models, which offers new treatment strategies.This article is highlighted in the In This Issue feature, p. 2483

Supplementary Figure from AXL and Error-Prone DNA Replication Confer Drug Resistance and Offer Strategies to Treat EGFR-Mutant Lung Cancer

Supplementary Data from AXL and Error-Prone DNA Replication Confer Drug Resistance and Offer Strategies to Treat EGFR-Mutant Lung Cancer

SummaryPatients with cancer of unknown primary (CUP) carry the double burden of an aggressive disease and reduced access to therapies. Experimental models summing up CUP features are pivotal for CUP biology investigation and drug testing. We derived two CUP cell lines (CUP#55 and #96), and corresponding patient-derived xenografts (PDXs), from ascites tumor cells. CUP cell lines and PDXs underwent histological, immune-phenotypical, molecular, and genomic characterization confirming the features of the original tumor. Genetic testing and FISH analysis identified FGFR2 amplification as therapeutic target in tumor tissues and patient-derived models. Drug-screening assays were performed to test the activity of FGFR2 targeting drug BGJ-398 (infigratinib) and the combination treatment with the MEK inhibitor trametinib, which proved to be synergic and exceptionally active, bothin vitroandin vivo. This study brings personalized therapy closer to CUP patients and paves the way to future applications of personalized medicine for metastatic patients with adverse prognosis.

The epidermal growth factor receptor (EGFR) is one of the main tumor drivers, and is an important therapeutic target for many cancers. Calcium is important in EGFR internalization and in EGFR signaling pathways. Sorcin is one of the most important calcium sensor proteins, overexpressed in many tumors, that promotes cell proliferation, migration, invasion, epithelial-to-mesenchymal transition, malignant progression and resistance to chemotherapeutic drugs. The present work elucidates an important mechanism that links calcium homeostasis to EGFR signaling in cancer. Sorcin and EGFR overexpression are significantly correlated in cancer patients. Sorcin directly binds EGFR in a calcium-dependent fashion and regulates calcium (dys)homeostasis linked to EGF-dependent EGFR signaling. Sorcin controls EGFR signaling, increases its recycling, activates the PI3K/AKT signaling cascade, and controls the RAS/ERK cascade, participating in the regulation of cellular migration and invasion. Sorcin expression leads to increased cell migration, invasion and EMT, via PI3K/AKT signaling; Sorcin silencing reverses these cancer features, synergistically with EGFR inhibitors.

Anticancer therapies have been limited by the emergence of mutations and other adaptations. In bacteria, antibiotics activate the SOS response, which mobilizes error-prone factors that allow for continuous replication at the cost of mutagenesis. We investigated whether the treatment of lung cancer with EGFR inhibitors (EGFRi) similarly engages hypermutators. In cycling drug-tolerant persister (DTP) cells and in EGFRi-treated patients presenting residual disease, we observed upregulation of GAS6, whereas ablation of GAS6's receptor, AXL, eradicated resistance. Reciprocally, AXL overexpression enhanced DTP survival and accelerated the emergence of T790M, an EGFR mutation typical to resistant cells. Mechanistically, AXL induces low-fidelity DNA polymerases and activates their organizer, RAD18, by promoting neddylation. Metabolomics uncovered another hypermutator, AXL-driven activation of MYC, and increased purine synthesis that is unbalanced by pyrimidines. Aligning anti-AXL combination treatments with the transition from DTPs to resistant cells cured patient-derived xenografts. Hence, similar to bacteria, tumors tolerate therapy by engaging pharmacologically targetable endogenous mutators. Significance: EGFR-mutant lung cancers treated with kinase inhibitors often evolve resistance due to secondary mutations. We report that in similarity to the bacterial SOS response stimulated by antibiotics, endogenous mutators are activated in drug-treated cells, and this heralds tolerance. Blocking the process prevented resistance in xenograft models, which offers new treatment strategies. This article is highlighted in the In This Issue feature, p. 2483

Epidemiologic data highlight sex differences in melanoma outcome. A putative role of sex hormones is still under investigation. Very few laboratory investigations have focused on the level of expression of estrogen receptors in melanoma. We evaluated the presence of estrogen receptors alpha (ERα) and beta (ERβ) in melanoma specimens from female patients with a previous history of breast carcinoma (BC). Moreover, another group of female patients undergoing ovarian stimulation (OS) were also compared to two control groups matched for age and melanoma staging. The study was performed at the IRCCS Policlinico di Sant'Orsola Hospital's Melanoma Unit from January 2017 to December 2019. The nuclear and cytoplasmatic immunohistochemical staining was evaluated and scored by the percentage of stained tumour cells: 0 (≤20%), 1 (21-50%) or 2 (≥50%). Twenty-eight specimens were analysed. ERβ nuclear presence was detected in all cases of women with a history of breast cancer. Cytoplasmatic ERβ was clearly expressed with a score of 2 in seven cases. In the respective control group, nuclear and cytoplasmatic ERβ expression was much lower. A cytoplasmatic ERα positivity was also detected in almost all cases. In the second group of women who experienced ovarian stimulation for Assisted Reproductive Technology (ART), a lower abundance of nuclear ERs was detected. Conversely, cytoplasmatic ERβ and α expression ranged widely. Melanoma of women treated with anti-estrogen therapy is generally more prone to express estrogen receptors compared with women of the same age and CM staging but also compared with women in fertile age with and without a history of OS.

ERBB3, also known as HER3, is a tyrosine kinase transmembrane receptor of the ERBB family. Upon binding to neuregulin 1 (NRG1), ERBB3 preferentially dimerizes with HER2 (ERBB2), in turn inducing aggressive features in several cancer types. The analysis of a dataset of breast cancer patients unveiled that higher ERBB3 mRNA expression correlates with shorter relapse-free survival in basal-like breast cancers, despite low ERBB3 expression in this breast cancer subtype. Administration of neuregulin 1 beta (NRG1β) significantly affected neither cellular proliferation nor the basal migratory ability of basal-like/triple-negative quasi-normal MCF10A breast cells, cultured in mono-layer conditions. Furthermore, no significant regulation in cell morphology or in the expression of basal/myoepithelial and luminal markers was observed upon stimulation with NRG1β. In non-adherent conditions, NRG1β administration to MCF10A cells did not significantly influence cell survival; however, it robustly induced cell growth as spheroids (3D growth). Intriguingly, a remarkable upregulation of ERBB3 and ERBB2 protein abundance was observed in 3D compared to 2D cell cultures, and NRG1β-induced 3D cell growth was efficiently prevented by the anti-HER2 monoclonal antibody pertuzumab. Similar results were obtained by the analysis of basal-like/triple-negative breast cancer cellular models, MDA-MB-468 and MDA-MB-231 cells, in which NRG1β induced anchorage-independent cell growth that in turn was prevented or reduced by the simultaneous administration of anti-HER2 neutralizing antibodies. Finally, the ability of pertuzumab in suppressing NRG1β-induced 3D growth was also evaluated and confirmed in MCF10A engineered with HER2-overexpression. We suggest that the NRG1/ERBB3/ERBB2 pathway promotes the anchorage-independent growth of basal-like breast cancer cells. Importantly, we provide evidence that ERBB2 neutralization, in particular by pertuzumab, robustly inhibits this process. Our results pave the way towards the development of novel anticancer strategies for basal-like breast cancer patients based on the interception of the NRG1/ERBB3/ERBB2 signaling axis.

ERBB4 is a tyrosine kinase receptor reported to exert both oncogenic and tumor suppressor activities. These paradoxical effects were suggested to stem from different ERBB4 homo-/hetero-dimers and/or isoforms. By stratifying breast cancer patients for clinical and molecular subtypes and ERBB4 mRNA abundance, we here report that higher ERBB4 levels correlate with longer relapse-free survival in breast cancer patients of HER2-enriched and luminal A molecular subtypes, proposing a cancer-protecting role for this receptor in these specific subgroups. We also observed that HER2-enriched breast cancers express intermediate ERBB4 mRNA levels compared to luminal and triple-negative/basal-like subgroups, which displayed the highest and the lowest levels, respectively. Inspired by these clinical data, we tested the activation of ERBB4 by Neuregulins as a potential anticancer strategy for HER2+ breast cancers. To this end, we employed two HER2+ breast cancer cellular models (BT474 and SKBR3), which express intermediate/high and low ERBB4 levels, respectively. Cell proliferation and motility were evaluated on these cellular models following treatments with Neuregulin 1 (NRG1), which activates both ERBB3 and ERBB4, or Neuregulin 4 (NRG4), which specifically activates ERBB4. Both NRG1 and NRG4 were used alone or in combination with anti-ERBB2 neutralizing antibodies, namely trastuzumab and pertuzumab. In vitro treatment with NRG1 on BT474 cells restrained cell growth and reduced the anti-proliferative efficacy of trastuzumab. In contrast, treatment with NRG1 on SKBR3 cells increased cell proliferation and migration, and partially or completely impaired the anti-proliferative/anti-migratory action of trastuzumab and/or pertuzumab. Importantly, in both the cell lines, treatment with NRG4 robustly potentiated the anti-proliferative action of trastuzumab and pertuzumab. Collectively, our data in HER2+ breast cancer cells highlight that NRG1 may exert both pro- and anti-proliferative effects, and may reduce the efficacy of anti-HER2 agents, whereas NRG4 may boost the anti-proliferative effects of anti-ERBB2 agents. We propose a provocative paradigm shift in the field of growth factors in cancer progression, suggesting the administration of ERBB4 ligands, such as Neuregulin 4, as a strategy to improve the efficacy of anti-ERBB2 agents.

Colorectal cancer (CRC) develops over several years, thus, early diagnosis and prevention are fundamental to reduce CRC burden. A new non-invasive blood test based on 4 mRNAs encompassing adhesion molecules such as CEACAM6, as well as a member of the collagen I superfamily, namely COL1A2, combined with LGALS4 and TSPAN8, was recently discovered and referred to as CELTIC panel [1]. The expression of the CELTiC panel was measured by quantitative PCR. The panel of putative biomarkers was subsequently evaluated in 101 subjects resulted positive to fecal immunochemical screening test (FIT) highlighting the potential to distinguish colonoscopy negative-FIT positive patients (NFIT, n=36), patients with low risk lesions (LR, n=36) and with high risk lesions or CRC (HR/CRC, n=92) [2]. In this study 174 healthy FIT negative subjects (FITN) were analysed [3] and compared to previous groups, evaluating also the influence of age and sex. Within the FITN group, CEACAM6 and COL1A2 display significantly lower expression in female than in male, confirming this sex difference of CEACAM6, a differentiation marker in normal colonocytes, also in the older groups (60–70 y.o.) and supporting current data on the importance of gender- and age-specific reference intervals for the early diagnosis of CRC [4,5]. The four genes showed significantly lower expression in FITN than in HR/CRC. Interestingly, TSPAN8 and COL1A2 were significantly lower expressed in FITN also than in NFIT and LR patients. TSPAN8, an integral membrane protein which upregulation promotes metastasis [6], was confirmed by logistic model as able to discriminate FITN from NFIT, LR and HR/CRC. Interestingly, also LGALS4, involved in cell-cell interaction and studied in CRC patients [7,8], was able to differentiate FITN from NFIT (false FIT positive). TSPAN8 and galectins have been described also in exosomes [9] suggesting the origin of the mRNAs of the CELTiC panel. Finally, the CELTIC panel showed good sensitivity (84-90%), specificity (76-81%) and AUC (0.87-0.89) to discriminate FITN from the other groups. The CELTiC panel was confirmed as a useful tool to diagnose CRC highlighting the importance of sex and age. A multicenter cross-sectional study will enroll 800 FIT positive subject at the Universities of Amsterdam and Bologna to better estimates the performances of the CELTiC panel and to further validate its robustness and usefulness in the early diagnosis of CRC and to exclude false FIT positive subjects.

Background EGFR targeting is currently the main treatment strategy for metastatic colorectal cancer (mCRC). Results of different clinical trials show that patients with wild-type KRAS and BRAF benefit from anti-EGFR monoclonal antibodies (moAbs) cetuximab (CTX) or panitumumab. Unfortunately, despite initial response, patients soon became refractory. Tumor heterogeneity and multiple escaping routes have been addressed as the main culprit, and, behind genomic alterations already described, changes in signaling pathways induced by drug pressure are emerging as mechanisms of acquired resistance. We previously reported an association between reduced sensitivity to CTX and increased expression of IL-1. However, how IL-1 mediates CTX resistance in mCRC is still unclear. Methods Under CTX treatment, the upregulation of IL-1R1 expression and a senescence program in sensitive colorectal cancer (CRC) cell lines is examined over time using qPCR, immunoblotting, and immunofluorescence. Results In sensitive CRC cells, IL-1 appeared responsible for a CTX-mediated G0 phase arrest. On the contrary, CTX-resistant CRC cells (CXR) maintained high mRNA levels of IL-1R1 and a post-senescence reprogramming, as indicated by increased SNAIL expression. Interestingly, treatment of CXR cells with a recombinant decoy, able to sequester the soluble form of IL-1, pushed CTX-resistant CRC cells back into a stage of senescence, thus blocking their proliferation. Our model suggests a trans-regulatory mechanism mediated by IL-1 on EGFR signaling. By establishing senescence and regulating EGFR activity and expression, IL-1 exposure ultimately bestows resistance. Conclusions To sum up, our findings point to the combined blockage of IL-1R and EGFR as a promising therapeutical approach to restore sensitivity to EGFR-targeting monoclonal antibodies.

IL-1 belongs to a family of 11 members and is one of the seven receptor-agonists with pro-inflammatory activity. Beyond its biological role as a regulator of the innate immune response, IL-1 is involved in stress and chronic inflammation, therefore it is responsible for several pathological conditions. In particular, IL-1 is known to exert a critical function in malignancies, influencing the tumor microenvironment and promoting cancer initiation and progression. Thus, it orchestrates immunosuppression recruiting pro-tumor immune cells of myeloid origin. Furthermore, new recent findings showed that this cytokine can be directly produced by tumor cells in a positive feedback loop and contributes to the failure of targeted therapy. Activation of anti-apoptotic signaling pathways and senescence are some of the mechanisms recently proposed, but the role of IL-1 in tumor cells refractory to standard therapies needs to be further investigated.

Sarcoids are the most common cutaneous tumor of equids and are caused by bovine papillomavirus (BPV). Different clinical subtypes of sarcoids are well characterized clinically but not histologically, and it is not known whether viral activity influences the clinical or histological appearance of the tumors. The aim of this study was to verify whether the development of different clinical types of sarcoids or the presence of certain histological features were associated with BPV distribution within the tumor. The presence of BPV was assessed by polymerase chain reaction (PCR) and visualized in histological sections by chromogenic in situ hybridization (CISH) in 74 equine sarcoids. Furthermore, to better characterize the molecular features of neoplastic cells, immunohistochemistry for S100, smooth muscle actin-α (αSMA), and fibroblast-associated protein-α (FAPα) was performed. The presence of BPV was confirmed in all tissues examined by either or both PCR and CISH (72/74, 97% each). Of 70/74 CISH-positive cases, signal distribution appeared as either diffuse (61/70, 87%) or subepithelial (9/70, 13%); the latter was more frequently observed in the verrucous subtype. However, no statistically significant association was found between clinical subtypes and specific histological features or hybridization pattern. Moreover, CISH signal for BPV was not detected in the epidermis overlying sarcoids nor in the tissue surrounding the neoplasms. By immunohistochemistry, αSMA confirmed the myofibroblastic differentiation of neoplastic cells in 28/74 (38%) sarcoids. Using tissue microarrays, FAPα labelling was observed in neoplastic fibroblasts of all sarcoids, suggesting this marker as a potential candidate for the immunohistochemical diagnosis of sarcoids.

In the last years, several efforts have been made to classify colorectal cancer (CRC) into well-defined molecular subgroups, representing the intrinsic inter-patient heterogeneity, known as Consensus Molecular Subtypes (CMSs). In this work, we performed a meta-analysis of 1700 CRC patients stratified into four CMSs. We identified a negative correlation between a high level of anaplastic lymphoma kinase (ALK) expression and relapse-free survival, exclusively in CMS1 subtype. Stemming from this observation, we tested several CMSs in vitro models with crizotinib (CZB) or alectinib (ALC), potent ALK inhibitors, already approved for clinical use. ALK interception strongly inhibits cell proliferation already at nanomolar doses, specifically in CMS1 cell lines, while no effect was found in CMS2/3/4 groups. Furthermore, in vivo imaging identified a role for ALK in the dynamic formation of 3D spheroids, which was impaired by the pharmacological inhibition of ALK. Consistently, CZB was responsible for the dampened activation of ALK along with the downstream AKT cascade. Mechanistically, we found a specific pro-apoptotic effect of ALK inhibition in CMS1 cell lines, both in 2D and 3D. Confocal analysis suggests that inhibition in CMS1 cells enhances cell-cell adhesion when growing in 3D. In agreement with our findings, an ALK signature encompassing 65 genes statistically associated with worse relapse-free survival in CMS1 subtype. Finally, the efficacy of ALK inhibition treatment was demonstrated in patient-derived organoids. Collectively, our findings suggest that ALK inhibition may represent an attractive therapy for CRC, and CMS classification may provide a useful tool to identify patients who could benefit from this treatment. These findings offer rationale and pharmacological strategies for the treatment of CMS1 CRC.

In mammals, glucocorticoid levels rise dramatically shortly before birth and prepare the foetus for post-natal life by promoting the maturation of the lungs and other organs. However, their impact on cardiac postnatal growth and regenerative plasticity is unknown.Here, we demonstrate that exposure to endogenous glucocorticoids facilitates cell cycle exit and reduces the proliferation of neonatal cardiomyocytes. This cytostatic activity is shared by several synthetic glucocorticoid receptor (GR) agonists routinely used in clinical settings. We also observed that GR levels increase in cardiomyocytes during early post-natal development. Importantly, in vivo cardiomyocyte-specific GR ablation delayed the transition from hyperplastic (increase in cell number) to hypertrophic (increase in cell size) growth. Further, GR ablation partially impaired cardiomyocyte maturation, reducing myofibrils-mitochondria organization along with the expression of genes involved in fatty acid metabolism, mitochondrial respiration and energy transfer from mitochondria to the cytosol. Finally, we show increased cardiomyocyte proliferation in GR ablated juvenile and adult cardiomyocytes in response to myocardial infarction in vivo, thus promoting cardiac tissue regeneration.We suggest that GR antagonization could serve as a strategy for heart regeneration based on endogenous cardiomyocyte renewal.

Background Cetuximab (CTX) is a monoclonal antibody targeting the Epidermal Growth Factor Receptor (EGFR), which is commonly utilized to treat patients with metastatic colorectal cancer (mCRC). Unfortunately, clinicians often observe a residual disease, with a population of cells surviving the treatment and eventually enabling CTX resistance. Our previous studies, performed with a cohort of 150 CRC xenopatients, associated poor response to CTX with increased abundance of a set of pro-inflammatory cytokines, including IL-1A, IL-1B and IL-8. IL-1 has been reported in the promotion of Senescence Associated Secretory Phenotype (SASP). Stemming from these observations, our current work aims to assess the effect of IL-1 pathway in CTX mediated senescence and resistance. Methods We employed a recombinant decoy (IL-1R1 TRAP), namely a soluble protein combining the human immunoglobulin Fc portion linked to the extracellular region of IL1-receptor, with the ability to sequester IL1 directly from the medium. We generated stable clones expressing a functional IL-1R1 TRAP, and tested the effects on proliferation of cancer cells growing both as monolayer and as 3D colonospheres. Next, the action of IL-1R1 TRAP decoy on EGFR downstream signalling pathways has been evaluated by analyses of MAPK and AKT axes. Results The analysis of colorectal cancer patients' datasets revealed that high levels of IL-1 receptor correlate with poor survival, specifically for the consensus molecular subtype 1 (CMS1). Next, mCRC patients not responding to CTX blockage, display higher level of IL-1R1 compared to the responsive ones. Furthermore, we found that IL-1R1 inhibition leads to decreased proliferation of colorectal cancer cells as consequence of a dampened MAPK and AKT signalling activation. Mechanistically, we show that CTX leads to a post-senescent phenotype as detected by bgalactosidase, HP1-g and p21 markers and stemness traits. Conclusions We are currently working on dissecting the contribution of IL1 signalling in resistance to CTX, as a consequence of the post-senescent phenotype. We conclude that IL1 signalling inhibition may represent a new therapeutic strategy suitable for patients who acquired refractoriness to EGFR targeted antibody therapy.

Three-dimensional (3D) culture systems like tumor spheroids represent useful in vitro models for drug screening and more broadly for cancer biology research, but the generation of uniform populations of spheroids remains challenging. The possibility to properly characterize spheroid properties would increase the reliability of these models. To address this issue different analysis were combined: i) a new device and relative analytical method for the accurate, simultaneous, and rapid measurement of mass density, weight, and size of spheroids, ii) confocal imaging, and iii) protein quantification, in a clinically relevant 3D model. The LoVo colon cancer cell line forming spheroids, treated with crizotinib (CZB) an ATP-competitive small-molecule inhibitor of the receptor tyrosine kinases, was employed to study and assess the correlation between biophysical and morphological parameters in both live and fixed cells. The new fluidic-based measurements allowed a robust phenotypical characterization of the spheroids structure, offering insights on the spheroids bulk and an accurate measurement of the tumor density. This analysis helps overcome the technical limits of the imaging that hardly penetrates the thickness of 3D structures. Accordingly, we were able to document that CZB treatment has an impact on mass density, which represents a key marker characterizing cancer cell treatment. Spheroid culture is the ultimate technology in drug discovery and the adoption of such precise measurement of the tumor characteristics can represent a key step forward for the accurate testing of treatment’s potential in 3D in vitro models.

Crosstalk between growth factors (GFs) and steroid hormones recurs in embryogenesis and is co-opted in pathology, but underlying mechanisms remain elusive. Our data from mammary cells imply that the crosstalk between the epidermal GF and glucocorticoids (GCs) involves transcription factors like p53 and NF-κB, along with reduced pausing and traveling of RNA polymerase II (RNAPII) at both promoters and bodies of GF-inducible genes. Essentially, GCs inhibit positive feedback loops activated by GFs and stimulate the reciprocal inhibitory loops. As expected, no alterations in DNA methylation accompany the transcriptional events instigated by either stimulus, but forced demethylation of regulatory regions broadened the repertoire of GF-inducible genes. We report that enhancers, like some promoters, are poised for activation by GFs and GCs. In addition, within the cooperative interface of the crosstalk, GFs enhance binding of the GC receptor to DNA and, in synergy with GCs, promote productive RNAPII elongation. Reciprocally, within the antagonistic interface GFs hyper-acetylate chromatin at unmethylated promoters and enhancers of genes involved in motility, but GCs hypoacetylate the corresponding regions. In conclusion, unmethylated genomic regions that encode feedback regulatory modules and differentially recruit RNAPII and acetylases/deacetylases underlie the crosstalk between GFs and a steroid hormone.

Graphical abstract, Prevention is essential to reduce Colorectal Cancer (CRC) mortality. We previously reported a panel of four genes: CEACAM6, LGALS4, TSPAN8, COL1A2 (CELTiC) able to discriminate patients with CRC. Here, we assessed the CELTiC panel by quantitative polymerase chain reaction, in the blood of 174 healthy subjects, who resulted negative to the faecal immunochemical test (FITN). Using non-parametric statistic and multinomial logistic models, the FITN were compared to previously analysed subjects: 36 false positive FIT (NFIT), who were negative at colonoscopy, 36 patients with low risk lesions (LR) and 92 patients with high risk lesions or CRC (HR/CRC). FITN showed a significantly lower expression of the four genes when compared to HR/CRC. Moreover, FITN showed a significantly lower expression of TSPAN8 and COL1A2 compared to NFIT and LR patients. The multinomial logistic model confirmed that TSPAN8 alone specifically discriminated FITN from NFIT, LR and HR/CRC, while LGALS4 was able to differentiate FITN from false positive FIT. Finally, ROC curves analysis of the comparisons between FITN and HR/CRC, LR or NFIT reported AUC greater than 0.87, with a sensitivity and specificity of 83% and 76%, respectively. The CELTiC panel was confirmed a useful tool to identify CRC patients and to discriminate false FIT positive subjects.

Summary The glucocorticoid receptor (GR) acts as a ubiquitous cortisol-dependent transcription factor (TF). To identify co-factors, we used protein-fragment complementation assays and found that GR recognizes FLI1 and additional ETS family proteins, TFs relaying proliferation and/or migration signals. Following steroid-dependent translocation of FLI1 and GR to the nucleus, the FLI1-specific domain (FLS) binds with GR and strongly enhances GR’s transcriptional activity. This interaction has functional consequences in Ewing sarcoma (ES), childhood and adolescence bone malignancies driven by fusions between EWSR1 and FLI1. In vitro, GR knockdown inhibited the migration and proliferation of ES cells, and in animal models, antagonizing GR (or lowering cortisol) retarded both tumor growth and metastasis from bone to lung. Taken together, our findings offer mechanistic rationale for repurposing GR-targeting drugs for the treatment of patients with ES., Graphical Abstract, Highlights • Glucocorticoids activate GR, an inducible TF regulating growth and metabolism • Protein complementation assays identified FLI1 and ERG as GR binders and activators • EWS-FLI1, a fusion protein, drives Ewing sarcoma (ES) and binds with activated GR • Pharmacological inhibition of GR activation retards progression in ES animal models, The single oncogene of Ewing sarcoma (ES), a childhood cancer, encodes a FLI1 fusion protein. Srivastava et al. report physical interactions between the fusion protein and the glucocorticoid receptor. Drug-induced inhibition of these interactions retards the progression of ES in mouse models.

During the past three decades, epidermal growth factor receptor (EGFR) targeting has been intensely pursued as a treatment strategy for metastatic colorectal cancer. One approach uses monoclonal antibodies to inhibit the extracellular domain of EGFR, thus blocking natural ligands binding. Unfortunately, patients often develop resistance, with consequent growth of tumor burden and relapse. This chapter discusses some of the mechanisms responsible for the failure of current therapies. Tumor heterogeneity is addressed as the main culprit for multiple escaping mechanisms, reflecting the high level of molecular heterogeneity present in each metastatic site. Genetic as well as nongenetic mechanisms are discussed, including acquisition of activating mutations in the mitogen-activated protein kinase axis mediators, epithelial-to-mesenchymal transition, activation of EGFR feedback loops, and signaling reactivation and bypass. Finally, autocrine and microenvironment secretion of growth factors that aid proliferative and anti-apoptotic signaling are also reported. The chapter concludes with an introduction of some promising combinatorial approaches, developed to overcome resistance to EGFR blockage.

Cetuximab (CX) is a monoclonal antibody targeting the Epidermal Growth Factor Receptor (EGFR), which is commonly utilized to treat patients with metastatic colorectal cancer (mCRC). Unfortunately, clinicians often observe a residual disease, with a population of cells surviving the treatment and eventually enabling CX resistance. Our previous studies, performed with a cohort of 150 CRC xenopatients, associated poor response to CX with increased abundance of a set of inflammatory cytokines, including IL1A, B and IL8. Stemming from these observations, our working hypothesis assumes that, resistance to CX is acquired, in a subset of CRC patients, through cell plasticity and consequent rewiring of signalling networks, which confer to tumors dependency on the IL1 pathway. In order to assess the effect of IL1 activity, we employed a colon cancer model unresponsive to cetuximab, as previously characterized in our laboratory. To inhibit activation of the IL1 pathway we used anakinra, an IL1-receptor antagonist and parthenolide, which modulates the activity of NF-kB, the transcription factor involved in the feed-forward loop of inflammation mediators. Furthermore, we employed a recombinant decoy (IL1R-Fc), namely a soluble protein combining the human immunoglobulin Fc portion linked to the extracellular region of IL1-receptor, with the ability to sequester IL1 directly from the medium. We generated stable clones of CXresistant cells expressing IL1R-Fc. Our preliminary results show that inhibition of IL1R leads to a proliferation decrease of colorectal cancer cells. These findings support the hypothesis of a compensatory activation of the IL1-receptor pathway in cetuximab-resistant CRC cells. Hence, modulating IL1 signalling might represent a new therapeutic strategy suitable for patients who acquired refractoriness to monoclonal antibody therapy.

// Valerio Gelfo 1, 2, * , Maria Teresa Rodia 1, * , Michela Pucci 1 , Massimiliano Dall’Ora 1 , Spartaco Santi 3, 4 , Rossella Solmi 1 , Lee Roth 5 , Moshit Lindzen 5 , Massimiliano Bonafe 1, 2 , Andrea Bertotti 6 , Elisabetta Caramelli 1 , Pier-Luigi Lollini 1 , Livio Trusolino 6 , Yosef Yarden 5 , Gabriele D’Uva 7, ** , Mattia Lauriola 1, 2, ** 1 Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna, Bologna, Italy 2 Center for Applied Biomedical Research (CRBA) S. Orsola-Malpighi University Hospital, University of Bologna, Bologna, Italy 3 Institute of Molecular Genetics, National Research Council of Italy, Bologna, Italy 4 Laboratory of Musculoskeletal Cell Biology, IOR-IRCCS, Bologna, Italy 5 Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel 6 Candiolo Cancer Institute-Fondazione del Piemonte per l’Oncologia (FPO), IRCCS, Department of Oncology, University of Torino, Candiolo, Italy 7 Scientific and Technology Pole, IRCCS MultiMedica, Milan, Italy * These authors have contributed equally to this work ** Co-last authors Correspondence to: Mattia Lauriola, email: mattia.lauriola@gmail.com Keywords: EGFR, transcriptional response, colon cancer, resistance, cetuximab Received: June 13, 2016 Accepted: September 21, 2016 Published: September 30, 2016 ABSTRACT Epidermal Growth Factor Receptor (EGFR) activates a robust signalling network to which colon cancer tumours often become addicted. Cetuximab, one of the monoclonal antibodies targeting this pathway, is employed to treat patients with colorectal cancer. However, many patients are intrinsically refractory to this treatment, and those who respond develop secondary resistance along time. Mechanisms of cancer cell resistance include either acquisition of new mutations or non genomic activation of alternative signalling routes. In this study, we employed a colon cancer model to assess potential mechanisms driving resistance to cetuximab. Resistant cells displayed increased ability to grow in suspension as colonspheres and this phenotype was associated with poorly organized structures. Factors secreted from resistant cells were causally involved in sustaining resistance, indeed administration to parental cells of conditioned medium collected from resistant cells was sufficient to reduce cetuximab efficacy. Among secreted factors, we report herein that a signature of inflammatory cytokines, including IL1A , IL1B and IL8 , which are produced following EGFR pathway activation, was associated with the acquisition of an unresponsive phenotype to cetuximab in vitro . This signature correlated with lack of response to EGFR targeting also in patient-derived tumour xenografts. Collectively, these results highlight the contribution of inflammatory cytokines to reduced sensitivity to EGFR blockade and suggest that inhibition of this panel of cytokines in combination with cetuximab might yield an effective treatment strategy for CRC patients refractory to anti-EGFR targeting.

Circular RNAs (circRNAs) are widespread circles of non-coding RNAs with largely unknown function. Because stimulation of mammary cells with the epidermal growth factor (EGF) leads to dynamic changes in the abundance of coding and non-coding RNA molecules, and culminates in the acquisition of a robust migratory phenotype, this cellular model might disclose functions of circRNAs. Here we show that circRNAs of EGF-stimulated mammary cells are stably expressed, while mRNAs and microRNAs change within minutes. In general, the circRNAs we detected are relatively long-lived and weakly expressed. Interestingly, they are almost ubiquitously co-expressed with the corresponding linear transcripts, and the respective, shared promoter regions are more active compared to genes producing linear isoforms with no detectable circRNAs. These findings imply that altered abundance of circRNAs, unlike changes in the levels of other RNAs, might not play critical roles in signaling cascades and downstream transcriptional networks that rapidly commit cells to specific outcomes.

Cetuximab (CTX) is a monoclonal antibody targeting the epidermal growth factor receptor (EGFR), commonly used to treat patients with metastatic colorectal cancer (mCRC). Unfortunately, objective remissions occur only in a minority of patients and are of short duration, with a population of cells surviving the treatment and eventually enabling CTX resistance. Our previous study on CRC xenopatients associated poor response to CTX with increased abundance of a set of pro-inflammatory cytokines, including the interleukins IL-1A, IL-1B and IL-8. Stemming from these observations, our current work aimed to assess the role of IL-1 pathway activity in CTX resistance. We employed a recombinant decoy TRAP IL-1, a soluble protein combining the human immunoglobulin Fc portion linked to the extracellular region of the IL-1-receptor (IL-1R1), able to sequester IL-1 directly from the medium. We generated stable clones expressing and secreting a functional TRAP IL-1 into the culture medium. Our results show that IL-1R1 inhibition leads to a decreased cell proliferation and a dampened MAPK and AKT axes. Moreover, CRC patients not responding to CTX blockage displayed higher levels of IL-1R1 than responsive subjects, and abundant IL-1R1 is predictive of survival in patient datasets specifically for the consensus molecular subtype 1 (CMS1). We conclude that IL-1R1 abundance may represent a therapeutic marker for patients who become refractory to monoclonal antibody therapy, while inhibition of IL-1R1 by TRAP IL-1 may offer a novel therapeutic strategy.

Trisomy 21 causes Down syndrome (DS), the most common human genetic disorder and the leading genetic cause of intellectual disability. The alteration of one-carbon metabolism was described as the possible metabolic cause of the intellectual disability development in subjects with DS. One of the biochemical pathways involved in the one-carbon group transfer is the folate cycle. The cytotoxic drug methotrexate (MTX) is a folic acid (FA) analogue which inhibits the activity of dihydrofolate reductase enzyme involved in the one-carbon metabolic cycle. Trisomy 21 cells are more sensitive to the MTX effect than euploid cells, and in 1986 Jerome Lejeune and Coll. demonstrated that MTX was twice as toxic in trisomy 21 lymphocytes than in control cells. In the present work, the rescue effect on MTX toxicity mediated by FA and some of its derivatives, tetrahydrofolate (THF), 5-formyl-THF, and 5-methyl-THF, in both normal and trisomy 21 skin fibroblast cells, was evaluated. A statistically significant rescue effect was obtained by 5-formyl-THF, 5-methyl-THF, and their combination, administered together with MTX. In conclusion, trisomy 21 fibroblast cell lines showed a good response to the rescue effects of 5-formyl-THF and 5-methyl-THF on the MTX toxicity almost as normal cell lines.