Aberrant MET activation impairs perinuclear actin cap organization with YAP1 cytosolic relocation.

Little is known about the signaling network responsible for the organization of the perinuclear actin cap, a recently identified structure holding unique roles in the regulation of nuclear shape and cell directionality. In cancer cells expressing a constitutively active MET, we show a rearrangement of the actin cap filaments, which crash into perinuclear patches associated with spherical nuclei, meandering cell motility and inactivation of the mechano-transducer YAP1. MET ablation is sufficient to reactivate YAP1 and restore the cap, leading to enhanced directionality and flattened nuclei. Consistently, the introduction of a hyperactive MET in normal epithelial cells, enhances nuclear height and alters the cap organization, as also confirmed by TEM analysis. Finally, the constitutively active YAP1 mutant YAP5SA is able to overcome the effects of oncogenic MET. Overall, our work describes a signaling axis empowering MET-mediated YAP1 dampening and actin cap misalignment, with implications for nuclear shape and cell motility.

Extracellular Vesicles and Epidermal Growth Factor Receptor Activation: Interplay of Drivers in Cancer Progression.

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.

Neuregulin 4 Boosts the Efficacy of Anti-ERBB2 Neutralizing Antibodies.

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.

NRG1/ERBB3/ERBB2 Axis Triggers Anchorage-Independent Growth of Basal-like/Triple-Negative Breast Cancer Cells.

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 (NRG1ß) 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 NRG1ß. In non-adherent conditions, NRG1ß 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 NRG1ß-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 NRG1ß 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 NRG1ß-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.

Senescence-associated reprogramming induced by interleukin-1 impairs response to EGFR neutralization.

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.

The autocrine loop of ALK receptor and ALKAL2 ligand is an actionable target in consensus molecular subtype 1 colon cancer.

BACKGROUND: 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). METHODS: In this work, we performed a meta-analysis of 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 cell lines, patient-derived organoids and mice with potent ALK inhibitors, already approved for clinical use. RESULTS: 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 tumor spheroids. Consistently, ALK appeares constitutively phosphorylated in CMS1, and it signals mainly through the AKT axis. Mechanistically, we found that CMS1 cells display several copies of ALKAL2 ligand and ALK-mRNAs, suggesting an autocrine loop mediated by ALKAL2 in the activation of ALK pathway, responsible for the invasive phenotype. Consequently, disruption of ALK axis mediates the pro-apoptotic action of CMS1 cell lines, both in 2D and 3D and enhanced cell-cell adhesion and e-cadherin organization. In agreement with all these findings, the ALK signature encompassing 65 genes statistically associated with worse relapse-free survival in CMS1 subtype. Finally, as a proof of concept, the efficacy of ALK inhibition was demonstrated in both patient-derived organoids and in tumor xenografts in vivo. CONCLUSIONS: Collectively, these findings suggest that ALK targeting 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.

IL-1 and senescence: Friends and foe of EGFR neutralization and immunotherapy.

Historically, senescence has been considered a safe program in response to multiple stresses in which cells undergo irreversible growth arrest. This process is characterized by morphological and metabolic changes, heterochromatin formation, and secretion of inflammatory components, known as senescence-associated secretory phenotype (SASP). However, recent reports demonstrated that anti-cancer therapy itself can stimulate a senescence response in tumor cells, the so-called therapy-induced senescence (TIS), which may represent a temporary bypass pathway that promotes drug resistance. In this context, several studies have shown that EGFR blockage, by TKIs or moAbs, promotes TIS by increasing IL-1 cytokine production, thus pushing cells into a "pseudo-senescent" state. Today, senotherapeutic agents are emerging as a potential strategy in cancer treatment thanks to their dual role in annihilating senescent cells and simultaneously preventing their awakening into a resistant and aggressive form. Here, we summarize classic and recent findings about the cellular processes driving senescence and SASP, and we provide a state-of-the-art of the anti-cancer strategies available so far that exploits the activation and/or blockade of senescence-based mechanisms.

Roles of IL-1 in Cancer: From Tumor Progression to Resistance to Targeted Therapies.

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.