All-trans retinoic acid exhibits anti-proliferative and differentiating activity in Merkel cell carcinoma cells via retinoid pathway modulation

BACKGROUND

The limited therapies available for treating Merkel cell carcinoma (MCC), a highly aggressive skin neoplasm, still pose clinical challenges, and novel treatments are required. Targeting retinoid signalling with retinoids, such as all-trans retinoic acid (ATRA), is a promising and clinically useful antitumor approach. ATRA drives tumour cell differentiation by modulating retinoid signalling, leading to anti-proliferative and pro-apoptotic effects. Although retinoid signalling is dysregulated in MCC, ATRA activity in this tumour is unknown. This study aimed to evaluate the impact of ATRA on the pathological phenotype of MCC cells.

METHODS

The effect of ATRA was tested in various Merkel cell polyomavirus-positive and polyomavirus-negative MCC cell lines in terms of cell proliferation, viability, migration and clonogenic abilities. In addition, cell cycle, apoptosis/cell death and the retinoid gene signature were evaluated upon ATRA treatments.

RESULTS

ATRA efficiently impaired MCC cell proliferation and viability in MCC cells. A strong effect in reducing cell migration and clonogenicity was determined in ATRA-treated cells. Moreover, ATRA resulted as strongly effective in arresting cell cycle and inducing apoptosis/cell death in all tested MCC cells. Enrichment analyses indicated that ATRA was effective in modulating the retinoid gene signature in MCC cells to promote cell differentiation pathways, which led to anti-proliferative and pro-apoptotic/cell death effects.

CONCLUSIONS

These results underline the potential of retinoid-based therapy for MCC management and might open the way to novel experimental approaches with other retinoids and/or combinatorial treatments.

Association of a gene-expression subtype to outcome and treatment response in patients with recurrent/metastatic head and neck squamous cell carcinoma treated with nivolumab

BACKGROUND

Immune checkpoint inhibitors have been approved and currently used in the clinical management of recurrent and metastatic head and neck squamous cell carcinoma (R/M HNSCC) patients. The reported benefit in clinical trials is variable and heterogeneous. Our study aims at exploring and comparing the predictive role of gene-expression signatures with classical biomarkers for immunotherapy-treated R/M HNSCC patients in a multicentric phase IIIb trial.

METHODS

Clinical data were prospectively collected in Nivactor tiral (single-arm, open-label, multicenter, phase IIIb clinical trial in platinum-refractory HNSCC treated with nivolumab). Findings were validated in an external independent cohort of immune-treated HNSCC patients, divided in long-term and short-term survivors (overall survival >18 and <6 months since the start of immunotherapy, respectively). Pretreatment tumor tissue specimen from immunotherapy-treated R/M HNSCC patients was used for PD-L1 (Tumor Proportion Score; Combined Positive Score (CPS)) and Tumor Mutational Burden (Oncopanel TSO500) evaluation and gene expression profiling; classical biomarkers and immune signatures (retrieved from literature) were challenged in the NIVACTOR dataset.

RESULTS

Cluster-6 (Cl6) stratification of NIVACTOR cases in high score (n=16, 20%) and low score (n=64, 80%) demonstrated a statistically significant and clinically meaningful improvement in overall survival in the high-score cases (p=0.00028; HR=4.34, 95% CI 1.84 to 10.22) and discriminative ability reached area under the curve (AUC)=0.785 (95% CI 0.603 to 0.967). The association of high-score Cl6 with better outcome was also confirmed in: (1) NIVACTOR progression-free survival (p=4.93E-05; HR=3.71, 95% CI 1.92 to 7.18) and objective-response-rate (AUC=0.785; 95% CI 0.603 to 0.967); (2) long survivors versus short survivors (p=0.00544). In multivariate Cox regression analysis, Cl6 was independent from Eastern Cooperative Oncology Group performance status, PDL1-CPS, and primary tumor site.

CONCLUSIONS

These data highlight the presence of underlying biological differences able to predict survival and response following treatment with immunotherapy in platinum-refractory R/M HNSCC that could have translational implications improving treatment selection.

TRIAL REGISTRATION NUMBER

EudraCT Number: 2017-000562-30.

Integrins regulate hERG1 dynamics by girdin-dependent Gαi3: signaling and modeling in cancer cells

The hERG1 potassium channel is aberrantly over expressed in tumors and regulates the cancer cell response to integrin-dependent adhesion. We unravel a novel signaling pathway by which integrin engagement by the ECM protein fibronectin promotes hERG1 translocation to the plasma membrane and its association with β1 integrins, by activating girdin-dependent Gαi3 proteins and protein kinase B (Akt). By sequestering hERG1, β1 integrins make it avoid Rab5-mediated endocytosis, where unbound channels are degraded. The cycle of hERG1 expression determines the resting potential (Vrest) oscillations and drives the cortical f-actin dynamics and thus cell motility. To interpret the slow biphasic kinetics of hERG1/β1 integrin interplay, we developed a mathematical model based on a generic balanced inactivation-like module. Integrin-mediated cell adhesion triggers two contrary responses: a rapid stimulation of hERG1/β1 complex formation, followed by a slow inhibition which restores the initial condition. The protracted hERG1/β1 integrin cycle determines the slow time course and cyclic behavior of cell migration in cancer cells.

The Yin Yang of Complement and Cancer

Cancer-related inflammation is a crucial component of the tumor microenvironment (TME). Complement activation occurs in cancer and supports the development of an inflammatory microenvironment. Complement has traditionally been considered a mechanism of immune resistance against cancer, and its activation is known to contribute to the cytolytic effects of antibody-based immunotherapeutic treatments. However, several studies have recently revealed that complement activation may exert protumoral functions by sustaining cancer-related inflammation and immunosuppression through different molecular mechanisms, targeting both the TME and cancer cells. These new discoveries have revealed that complement manipulation can be considered a new strategy for cancer therapies. Here we summarize our current understanding of the mechanisms by which the different elements of the complement system exert antitumor or protumor functions, both in preclinical studies and in human tumorigenesis. Complement components can serve as disease biomarkers for cancer stratification and prognosis and be exploited for tumor treatment.

Identification of protein biomarkers for prediction of response to platinum-based treatment regimens in patients with non-small cell lung cancer

The majority of patients with resected stage II-IIIA non-small cell lung cancer (NSCLC) are treated with platinum-based adjuvant chemotherapy (ACT) in a one-size-fits-all approach. However, a significant number of patients do not derive clinical benefit, and no predictive patient selection biomarker is currently available. Using mass spectrometry-based proteomics, we have profiled tumour resection material of 2 independent, multi-centre cohorts of in total 67 patients with NSCLC who underwent ACT. Unsupervised cluster analysis of both cohorts revealed a poor response/survival sub-cluster composed of ~ 25% of the patients, that displayed a strong epithelial-mesenchymal transition signature and stromal phenotype. Beyond this stromal sub-population, we identified and validated platinum response prediction biomarker candidates involved in pathways relevant to the mechanism of action of platinum drugs, such as DNA damage repair, as well as less anticipated processes such as those related to the regulation of actin cytoskeleton. Integration with pre-clinical proteomics data supported a role for several of these candidate proteins in platinum response prediction. Validation of one of the candidates (HMGB1) in a third independent patient cohort using immunohistochemistry highlights the potential of translating these proteomics results to clinical practice.

Increased interleukin-6/C-reactive protein levels are associated with the upregulation of the adenosine pathway and serve as potential markers of therapeutic resistance to immune checkpoint inhibitor-based therapies in non-small cell lung cancer

BACKGROUND

Systemic immune activation, hallmarked by C-reactive protein (CRP) and interleukin-6 (IL-6), can modulate antitumor immune responses. In this study, we evaluated the role of IL-6 and CRP in the stratification of patients with non-small cell lung cancer (NSCLC) treated with immune checkpoint inhibitors (ICIs). We also interrogated the underlying immunosuppressive mechanisms driven by the IL-6/CRP axis.

METHODS

In cohort A (n=308), we estimated the association of baseline CRP with objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) in patients with NSCLC treated with ICIs alone or with chemo-immunotherapy (Chemo-ICI). Baseline tumor bulk RNA sequencing (RNA-seq) of lung adenocarcinomas (LUADs) treated with pembrolizumab (cohort B, n=59) was used to evaluate differential expression of purine metabolism, as well as correlate IL-6 expression with PFS. CODEFACS approach was applied to deconvolve cohort B to characterize the tumor microenvironment by reconstructing the cell-type-specific transcriptome from bulk expression. Using the LUAD cohort from The Cancer Genome Atlas (TCGA) we explored the correlation between IL-6 expression and adenosine gene signatures. In a third cohort (cohort C, n=18), plasma concentrations of CRP, adenosine 2a receptor (A2aR), and IL-6 were measured using ELISA.

RESULTS

In cohort A, 67.2% of patients had a baseline CRP≥10 mg/L (CRP-H). Patients with CRP-H achieved shorter OS (8.6 vs 14.8 months; p=0.006), shorter PFS (3.3 vs 6.6 months; p=0.013), and lower ORR (24.7% vs 46.3%; p=0.015). After adjusting for relevant clinical variables, CRP-H was confirmed as an independent predictor of increased risk of death (HR 1.51, 95% CI: 1.09 to 2.11) and lower probability of achieving disease response (OR 0.34, 95% CI: 0.13 to 0.89). In cohort B, RNA-seq analysis demonstrated higher IL-6 expression on tumor cells of non-responders, along with a shorter PFS (p<0.05) and enrichment of the purinergic pathway. Within the TCGA LUAD cohort, tumor IL-6 expression strongly correlated with the adenosine signature (R=0.65; p<2.2e-16). Plasma analysis in cohort C demonstrated that CRP-H patients had a greater median baseline level of A2aR (6.0 ng/mL vs 1.3 ng/mL; p=0.01).

CONCLUSIONS

This study demonstrates CRP as a readily available blood-based prognostic biomarker in ICI-treated NSCLC. Additionally, we elucidate a potential link of the CRP/IL-6 axis with the immunosuppressive adenosine signature pathway that could drive inferior outcomes to ICIs in NSCLC and also offer novel therapeutic avenues.

Physical activity and/or dietary intervention in overweight or obese breast cancer survivors: results of the InForma randomized trial

PURPOSE

This study aimed to test the efficacy of a 6-month intervention on weight loss in a group of overweight or obese breast cancer (BC) survivors. We promoted adherence to a healthy diet or/and to increase physical activity, making use of a step counter device. Here we present results regarding the change in anthropometric measures and blood parameters.

METHODS

266 women treated for BC with a BMI ≥ 25 kg/m2 were randomized to a 6-month intervention into four arms: Dietary Intervention (DI); Physical Activity Intervention (PAI); Physical Activity and Dietary Intervention (PADI); Minimal Intervention (MI). Women were offered individualized counseling by a dietitian, a physiotherapist and a psychologist. Participants were followed up for an additional 18 months.

RESULTS

231 women completed the 6-month intervention and 167 completed the additional 18-month follow-up. Respectively, 37.5% and 36.7% of women included in the DI and PADI arm reached the objective of the trial (weight reduction > 5%). Significant weight and circumferences decrease was observed at 6-month in the four arms. Weight decrease was more pronounced in the DI (-4.7% ± 5.0%) and PADI (-3.9% ± 4.5%) arms, persisted over time (at 12 and 24 months), where counseling was mainly focused on the dietic component. The intervention had an effect on the glucose level with a significant reduction in whole population (-0.9 ± 11.7 p-value 0.02) and most pronounced in the PADI arm (-2.4 ± 7.8 p-value 0.03).

CONCLUSIONS

Lifestyle intervention mainly focused on the dietetic component and making use of a step counter improved body weight, circumferences and glucose levels.

IMPLICATIONS FOR CANCER SURVIVORS

A personalized approach yields a potential clinical benefit for BC survivors.

Use of Poly Lactic-co-glycolic Acid Nano and Micro Particles in the Delivery of Drugs Modulating Different Phases of Inflammation

Chronic inflammation contributes to the pathogenesis of many diseases, including apparently unrelated conditions such as metabolic disorders, cardiovascular diseases, neurodegenerative diseases, osteoporosis, and tumors, but the use of conventional anti-inflammatory drugs to treat these diseases is generally not very effective given their adverse effects. In addition, some alternative anti-inflammatory medications, such as many natural compounds, have scarce solubility and stability, which are associated with low bioavailability. Therefore, encapsulation within nanoparticles (NPs) may represent an effective strategy to enhance the pharmacological properties of these bioactive molecules, and poly lactic-co-glycolic acid (PLGA) NPs have been widely used because of their high biocompatibility and biodegradability and possibility to finely tune erosion time, hydrophilic/hydrophobic nature, and mechanical properties by acting on the polymer's composition and preparation technique. Many studies have been focused on the use of PLGA-NPs to deliver immunosuppressive treatments for autoimmune and allergic diseases or to elicit protective immune responses, such as in vaccination and cancer immunotherapy. By contrast, this review is focused on the use of PLGA NPs in preclinical in vivo models of other diseases in which a key role is played by chronic inflammation or unbalance between the protective and reparative phases of inflammation, with a particular focus on intestinal bowel disease; cardiovascular, neurodegenerative, osteoarticular, and ocular diseases; and wound healing.

Frenemies in the Microenvironment: Harnessing Mast Cells for Cancer Immunotherapy

Tumor development, progression, and resistance to therapies are influenced by the interactions between tumor cells and the surrounding microenvironment, comprising fibroblasts, immune cells, and extracellular matrix proteins. In this context, mast cells (MCs) have recently emerged as important players. Yet, their role is still controversial, as MCs can exert pro- or anti-tumor functions in different tumor types depending on their location within or around the tumor mass and their interaction with other components of the tumor microenvironment. In this review, we describe the main aspects of MC biology and the different contribution of MCs in promoting or inhibiting cancer growth. We then discuss possible therapeutic strategies aimed at targeting MCs for cancer immunotherapy, which include: (1) targeting c-Kit signaling; (2) stabilizing MC degranulation; (3) triggering activating/inhibiting receptors; (4) modulating MC recruitment; (5) harnessing MC mediators; (6) adoptive transferring of MCs. Such strategies should aim to either restrain or sustain MC activity according to specific contexts. Further investigation would allow us to better dissect the multifaceted roles of MCs in cancer and tailor novel approaches for an "MC-guided" personalized medicine to be used in combination with conventional anti-cancer therapies.

Preclinical Validation of an Advanced Therapy Medicinal Product Based on Cytotoxic T Lymphocytes Specific for Mutated Nucleophosmin (NPM1mut) for the Treatment of NPM1mut-Acute Myeloid Leukemia

Acute myeloid leukemia (AML) with nucleophosmin (NPM1) genetic mutations is the most common subtype in adult patients. Refractory or relapsed disease in unfit patients or after allogeneic hematopoietic stem cell transplantation (allo-HSCT) has a poor prognosis. NPM1-mutated protein, stably expressed on tumor cells but not on normal tissues, may serve as an ideal target for NPM1-mutated AML immunotherapy. The study aim was to investigate the feasibility of producing mutated-NPM1-specific cytotoxic T cells (CTLs) suitable for somatic cell therapy to prevent or treat hematologic relapse in patients with NPM1-mutated AML. T cells were expanded or primed from patient or donor peripheral blood mononuclear cells by NPM1-mutated protein-derived peptides, and tested for leukemia antigen-targeted cytotoxic activity, cytokine production and hematopoietic precursor inhibitory effect. We found that mutated-NPM1-specific CTLs, displaying specific cytokine production and high-level cytotoxicity against patients' leukemia blasts, and limited inhibitory activity in clonogenic assays, could be obtained from both patients and donors. The polyfunctional mutated-NPM1-specific CTLs included both CD8+ and CD4+ T cells endowed with strong lytic capacity. Our results suggest that mutated-NPM1-targeted CTLs may be a useful therapeutic option to control low-tumor burden relapse following conventional chemotherapy in older NPM1-mutated AML patients or eradicate persistent MRD after HSCT.

Analysis of Radiation Toxicity in Mammalian Cells Stably Transduced with Mitochondrial Stat3

A coordinated action between nuclear and mitochondrial activities is essential for a proper cellular response to genotoxic stress. Several nuclear transcription factors, including STAT3, translocate to mitochondria to exert mitochondrial function regulation; however, the role of mitochondrial STAT3 (mitoSTAT3) under stressed conditions is still poorly understood. In this study, we examined whether the stable expression of mitoSTAT3 wild-type or mutated at the conserved serine residue (Ser727), which is involved in the mitochondrial function of STAT3, can affect the DNA damage response to UVC radiation. To address this issue, we generated mammalian cells (NIH-3T3 and HCT-116 cells) stably transduced to express the mitochondrial-targeted Stat3 gene in its wild-type or Ser727 mutated forms. Our results show that cell proliferation is enhanced in mitoStat3-transduced cells under both non-stressed and stressed conditions. Once irradiated with UVC, cells expressing wild-type mitoSTAT3 showed the highest cell survival, which was associated with a significant decrease in cell death. Low levels of oxidative stress were detected in UVC-irradiated NIH-3T3 cells expressing mitoSTAT3 wild-type or serine-related dominant active form (Ser727D), confirming a role of mitochondrial STAT3 in minimizing oxidant cellular stress that provides an advantage for cell survival.

AurkA nuclear localization is promoted by TPX2 and counteracted by protein degradation

The AurkA kinase is a well-known mitotic regulator, frequently overexpressed in tumors. The microtubule-binding protein TPX2 controls AurkA activity, localization, and stability in mitosis. Non-mitotic roles of AurkA are emerging, and increased nuclear localization in interphase has been correlated with AurkA oncogenic potential. Still, the mechanisms leading to AurkA nuclear accumulation are poorly explored. Here, we investigated these mechanisms under physiological or overexpression conditions. We observed that AurkA nuclear localization is influenced by the cell cycle phase and nuclear export, but not by its kinase activity. Importantly, AURKA overexpression is not sufficient to determine its accumulation in interphase nuclei, which is instead obtained when AURKA and TPX2 are co-overexpressed or, to a higher extent, when proteasome activity is impaired. Expression analyses show that AURKA, TPX2, and the import regulator CSE1L are co-overexpressed in tumors. Finally, using MCF10A mammospheres we show that TPX2 co-overexpression drives protumorigenic processes downstream of nuclear AurkA. We propose that AURKA/TPX2 co-overexpression in cancer represents a key determinant of AurkA nuclear oncogenic functions.

SAMHD1 restricts the deoxyguanosine triphosphate pool contributing to telomere stability in telomerase-positive cells

SAMHD1 (Sterile alpha motif and histidine/aspartic acid domain-containing protein 1) is a dNTP triphosphohydrolase crucial in the maintenance of balanced cellular dNTP pools, which support genome integrity. In SAMHD1 deficient fibroblasts isolated from Aicardi-Goutières Syndrome (AGS) patients, all four DNA precursors are increased and markedly imbalanced with the largest effect on dGTP, a key player in the modulation of telomerase processivity. Here, we present data showing that SAMHD1, by restricting the dGTP pool, contributes to telomere maintenance in hTERT-immortalized human fibroblasts from AGS patients as well as in telomerase positive cancer cell lines. Only in cells expressing telomerase, the lack of SAMHD1 causes excessive lengthening of telomeres and telomere fragility, whereas primary fibroblasts lacking both SAMHD1 and telomerase enter normally into senescence. Telomere lengthening observed in SAMHD1 deficient but telomerase proficient cells is a gradual process, in accordance with the intrinsic property of telomerase of adding only a few tens of nucleotides for each cycle. Therefore, only a prolonged exposure to high dGTP content causes telomere over-elongation. hTERT-immortalized AGS fibroblasts display also high fragility of chromosome ends, a marker of telomere replication stress. These results not only demonstrate the functional importance of dGTP cellular level but also reveal the critical role played by SAMHD1 in restraining telomerase processivity and safeguarding telomere stability.

The PARP1 Inhibitor AZD5305 Impairs Ovarian Adenocarcinoma Progression and Visceral Metastases in Patient-derived Xenografts Alone and in Combination with Carboplatin

PARP inhibitors (PARPi) have changed the management of patients with ovarian cancer and their effectiveness has been demonstrated especially in homologous recombination repair–deficient tumors. These first-generation drugs target PARP1, but also PARP2 and other family members potentially responsible for adverse effects that limit their therapeutic potential and restrict their use in combination with chemotherapeutic agents.

We investigated ovarian cancer patient-derived xenografts (OC-PDXs) to assess whether malignant progression could be impaired by a novel inhibitor selective for PARP1 (AZD5305) and to assess the potential of its combination with carboplatin (CPT), the standard-of-care for patients with ovarian cancer.

In BRCA-mutated OC-PDXs, AZD5305 achieved greater tumor regressions and longer duration of response as well as a superior impairment of visceral metastasis and improved survival benefit compared with the first-generation dual PARP1/2 inhibitors.

The combination of AZD5305 plus CPT was more efficacious than single agents. Subcutaneously growing tumors experienced regression that persisted after therapy stopped. Combination efficacy was greater against tumors that did not respond well to platinum, even at a dose at which AZD5305 monotherapy was ineffective. The combination therapy impaired metastatic dissemination and significantly prolonged the lifespan of mice bearing OC-PDXs in their abdomen. This combination benefit was evident even when CPT was used at suboptimal doses, and was superior to full-dose platinum treatment.

These preclinical studies demonstrate that the PARP1-selective inhibitor AZD5305 retains and improves the therapeutic benefit of the first-generation PARPi, providing an opportunity to maximize benefits for this class of anticancer agents.

GEMC1 and MCIDAS interactions with SWI/SNF complexes regulate the multiciliated cell-specific transcriptional program

Multiciliated cells (MCCs) project dozens to hundreds of motile cilia from their apical surface to promote the movement of fluids or gametes in the mammalian brain, airway or reproductive organs. Differentiation of MCCs requires the sequential action of the Geminin family transcriptional activators, GEMC1 and MCIDAS, that both interact with E2F4/5-DP1. How these factors activate transcription and the extent to which they play redundant functions remains poorly understood. Here, we demonstrate that the transcriptional targets and proximal proteomes of GEMC1 and MCIDAS are highly similar. However, we identified distinct interactions with SWI/SNF subcomplexes; GEMC1 interacts primarily with the ARID1A containing BAF complex while MCIDAS interacts primarily with BRD9 containing ncBAF complexes. Treatment with a BRD9 inhibitor impaired MCIDAS-mediated activation of several target genes and compromised the MCC differentiation program in multiple cell based models. Our data suggest that the differential engagement of distinct SWI/SNF subcomplexes by GEMC1 and MCIDAS is required for MCC-specific transcriptional regulation and mediated by their distinct C-terminal domains.

Quantifying heterogeneity to drug response in cancer-stroma kinetics

A crucial challenge in medicine is choosing which drug (or combination) will be the most advantageous for a particular patient. Usually, drug response rates differ substantially, and the reasons for this response unpredictability remain ambiguous. Consequently, it is central to classify features that contribute to the observed drug response variability. Pancreatic cancer is one of the deadliest cancers with limited therapeutic achievements due to the massive presence of stroma that generates an environment that enables tumor growth, metastasis, and drug resistance. To understand the cancer-stroma cross talk within the tumor microenvironment and to develop personalized adjuvant therapies, there is a necessity for effective approaches that offer measurable data to monitor the effect of drugs at the single-cell level. Here, we develop a computational approach, based on cell imaging, that quantifies the cellular cross talk between pancreatic tumor cells (L3.6pl or AsPC1) and pancreatic stellate cells (PSCs), coordinating their kinetics in presence of the chemotherapeutic agent gemcitabine. We report significant heterogeneity in the organization of cellular interactions in response to the drug. For L3.6pl cells, gemcitabine sensibly decreases stroma-stroma interactions but increases stroma-cancer interactions, overall enhancing motility and crowding. In the AsPC1 case, gemcitabine promotes the interactions among tumor cells, but it does not affect stroma-cancer interplay, possibly suggesting a milder effect of the drug on cell dynamics.

Novel Lymphocyte-Independent Antitumor Activity by PD-1 Blocking Antibody against PD-1+ Chemoresistant Lung Cancer Cells

PURPOSE

Antibodies against the lymphocyte PD-1 (aPD-1) receptor are cornerstone agents for advanced non-small cell lung cancer (NSCLC), based on their ability to restore the exhausted antitumor immune response. Our study reports a novel, lymphocyte-independent, therapeutic activity of aPD-1 against NSCLC, blocking the tumor-intrinsic PD-1 receptors on chemoresistant cells.

EXPERIMENTAL DESIGN

PD-1 in NSCLC cells was explored in vitro at baseline, including stem-like pneumospheres, and following treatment with cisplatin both at transcriptional and protein levels. PD-1 signaling and RNA sequencing were assessed. The lymphocyte-independent antitumor activity of aPD-1 was explored in vitro, by PD-1 blockade and stimulation with soluble ligand (PD-L1s), and in vivo within NSCLC xenograft models.

RESULTS

We showed the existence of PD-1+ NSCLC cell subsets in cell lines and large in silico datasets (Cancer Cell Line Encyclopedia and The Cancer Genome Atlas). Cisplatin significantly increased PD-1 expression on chemo-surviving NSCLC cells (2.5-fold P = 0.0014), while the sequential treatment with anti-PD-1 Ab impaired their recovery after chemotherapy. PD-1 was found to be associated with tumor stemness features. PD-1 expression was enhanced in NSCLC stem-like pneumospheres (P < 0.0001), significantly promoted by stimulation with soluble PD-L1 (+27% ± 4, P < 0.0001) and inhibited by PD-1 blockade (-30% ± 3, P < 0.0001). The intravenous monotherapy with anti-PD-1 significantly inhibited tumor growth of NSCLC xenografts in immunodeficient mice, without the contribution of the immune system, and delayed the occurrence of chemoresistance when combined with cisplatin.

CONCLUSIONS

We report first evidence of a novel lymphocyte-independent activity of anti-PD-1 antibodies in NSCLC, capable of inhibiting chemo-surviving NSCLC cells and exploitable to contrast disease relapses following chemotherapy. See related commentary by Augustin et al., p. 505.

NASH and Hepatocellular Carcinoma: Immunology and Immunotherapy

The last 10 years have revolutionized our basic understanding of nonalcoholic fatty liver disease and consequent liver cancer. It has become clear that several innate and adaptive immune cells play an important role in initiating, maintaining, or exacerbating nonalcoholic steatohepatitis (NASH)-a disease that has been recently defined as autoaggressive. Despite improved disease management aimed at reducing the progression of fibrosis, NASH is set to become a leading cause for hepatocellular carcinoma (HCC). Preliminary data from preclinical studies suggest that immunotherapy efficacy may be reduced in NASH-related HCC compared with viral HCC; however, conclusive evidence supporting clinical translation of these findings is lacking. Comprehensive clinical and immunologic phenotyping of mechanisms linking NASH progression with carcinogenesis and therapeutic resistance is key to prevent progression to cirrhosis, improve monitoring and stratification of NASH according to predicted cancer risk, and ultimately increase survival of patients with NASH-HCC. In this review, we summarize the state of the art in the field of NASH and NASH-HCC with focus on immunobiology. We discuss preclinical and clinical findings underpinning NASH as an immunologically distinct pro-tumorigenic disease entity, and explore areas of potential therapeutic vulnerabilities in NASH-associated HCC.

Plasma miR-151-3p as a Candidate Diagnostic Biomarker for Head and Neck Cancer: A Cross-sectional Study within the INHANCE Consortium

BACKGROUND

Identification of screening tests for the detection of head and neck cancer (HNC) at an early stage is an important strategy to improving prognosis. Our objective was to identify plasma circulating miRNAs for the diagnosis of HNC (oral and laryngeal subsites), within a multicenter International Head and Neck Cancer Epidemiology consortium.

METHODS

A high-throughput screening phase with 754 miRNAs was performed in plasma samples of 88 cases and 88 controls, followed by a validation phase of the differentially expressed miRNAs, identified in the screening, in samples of 396 cases and 396 controls. Comparison of the fold changes (FC) was carried out using the Wilcoxon rank-sum test and the Dunn multiple comparison test.

RESULTS

We identified miR-151-3p (FC = 1.73, P = 0.007) as differentially expressed miRNAs in the screening and validation phase. The miR-151-3p was the only overexpressed miRNA in validation sample of patients with HNC with early stage at diagnosis (FC = 1.81, P = 0.008) and it was confirmed upregulated both in smoker early-stage cases (FC = 3.52, P = 0.024) and in nonsmoker early-stage cases (FC = 1.60, P = 0.025) compared with controls.

CONCLUSIONS

We identified miR-151-3p as an early marker of HNC. This miRNA was the only upregulated in patients at early stages of the disease, independently of the smoking status.

IMPACT

The prognosis for HNC is still poor. The discovery of a new diagnostic biomarker could lead to an earlier tumor discovery and therefore to an improvement in patient prognosis.

p140Cap Regulates the Composition and Localization of the NMDAR Complex in Synaptic Lipid Rafts

The NMDARs are key players in both physiological and pathologic synaptic plasticity because of their involvement in many aspects of neuronal transmission as well as learning and memory. The contribution in these events of different types of GluN2A-interacting proteins is still unclear. The p140Cap scaffold protein acts as a hub for postsynaptic complexes relevant to psychiatric and neurologic disorders and regulates synaptic functions, such as the stabilization of mature dendritic spine, memory consolidation, LTP, and LTD. Here we demonstrate that p140Cap directly binds the GluN2A subunit of NMDAR and modulates GluN2A-associated molecular network. Indeed, in p140Cap KO male mice, GluN2A is less associated with PSD95 both in ex vivo synaptosomes and in cultured hippocampal neurons, and p140Cap expression in KO neurons can rescue GluN2A and PSD95 colocalization. p140Cap is crucial in the recruitment of GluN2A-containing NMDARs and, consequently, in regulating NMDARs' intrinsic properties. p140Cap is associated to synaptic lipid-raft (LR) and to soluble postsynaptic membranes, and GluN2A and PSD95 are less recruited into synaptic LR of p140Cap KO male mice. Gated-stimulated emission depletion microscopy on hippocampal neurons confirmed that p140Cap is required for embedding GluN2A clusters in LR in an activity-dependent fashion. In the synaptic compartment, p140Cap influences the association between GluN2A and PSD95 and modulates GluN2A enrichment into LR. Overall, such increase in these membrane domains rich in signaling molecules results in improved signal transduction efficiency.SIGNIFICANCE STATEMENT Here we originally show that the adaptor protein p140Cap directly binds the GluN2A subunit of NMDAR and modulates the GluN2A-associated molecular network. Moreover, we show, for the first time, that p140Cap also associates to synaptic lipid rafts and controls the selective recruitment of GluN2A and PSD95 to this specific compartment. Finally, gated-stimulated emission depletion microscopy on hippocampal neurons confirmed that p140Cap is required for embedding GluN2A clusters in lipid rafts in an activity-dependent fashion. Overall, our findings provide the molecular and functional dissection of p140Cap as a new active member of a highly dynamic synaptic network involved in memory consolidation, LTP, and LTD, which are known to be altered in neurologic and psychiatric disorders.

Inhibition of ERK5 Elicits Cellular Senescence in Melanoma via the Cyclin-Dependent Kinase Inhibitor p21

Melanoma is the deadliest skin cancer with a very poor prognosis in advanced stages. Although targeted and immune therapies have improved survival, not all patients benefit from these treatments. The mitogen-activated protein kinase ERK5 supports the growth of melanoma cells in vitro and in vivo. However, ERK5 inhibition results in cell-cycle arrest rather than appreciable apoptosis. To clarify the role of ERK5 in melanoma growth, we performed transcriptomic analyses following ERK5 knockdown in melanoma cells expressing BRAFV600E and found that cellular senescence was among the most affected processes. In melanoma cells expressing either wild-type or mutant (V600E) BRAF, both genetic and pharmacologic inhibition of ERK5 elicited cellular senescence, as observed by a marked increase in senescence-associated β-galactosidase activity and p21 expression. In addition, depletion of ERK5 from melanoma cells resulted in increased levels of CXCL1, CXCL8, and CCL20, proteins typically involved in the senescence-associated secretory phenotype. Knockdown of p21 suppressed the induction of cellular senescence by ERK5 blockade, pointing to p21 as a key mediator of this process. In vivo, ERK5 knockdown or inhibition with XMD8-92 in melanoma xenografts promoted cellular senescence. Based on these results, small-molecule compounds targeting ERK5 constitute a rational series of prosenescence drugs that may be exploited for melanoma treatment. SIGNIFICANCE: This study shows that targeting ERK5 induces p21-mediated cellular senescence in melanoma, identifying a prosenescence effect of ERK5 inhibitors that may be exploited for melanoma treatment.

Tumoral Neuroligin 1 Promotes Cancer-Nerve Interactions and Synergizes with the Glial Cell Line-Derived Neurotrophic Factor

Many nervous proteins are expressed in cancer cells. In this report, we asked whether the synaptic protein neuroligin 1 (NLGN1) was expressed by prostatic and pancreatic carcinomas; in addition, given the tendency of these tumors to interact with nerves, we asked whether NLGN1 played a role in this process. Through immunohistochemistry on human tissue microarrays, we showed that NLGN1 is expressed by prostatic and pancreatic cancer tissues in discrete stages and tumor districts. Next, we performed in vitro and in vivo assays, demonstrating that NLGN1 promotes cancer cell invasion and migration along nerves. Because of the established role of the neurotrophic factor glial cell line-derived neurotrophic factor (GDNF) in tumor-nerve interactions, we assessed a potential NLGN1-GDNF cooperation. We found that blocking GDNF activity with a specific antibody completely inhibited NLGN1-induced in vitro cancer cell invasion of nerves. Finally, we demonstrated that, in the presence of NLGN1, GDNF markedly activates cofilin, a cytoskeletal regulatory protein, altering filopodia dynamics. In conclusion, our data further prove the existence of a molecular and functional cross-talk between the nervous system and cancer cells. NLGN1 was shown here to function along one of the most represented neurotrophic factors in the nerve microenvironment, possibly opening new therapeutic avenues.

Castration-Induced Downregulation of SPARC in Stromal Cells Drives Neuroendocrine Differentiation of Prostate Cancer

Fatal neuroendocrine differentiation (NED) of castration-resistant prostate cancer is a recurrent mechanism of resistance to androgen deprivation therapies (ADT) and antiandrogen receptor pathway inhibitors (ARPI) in patients. The design of effective therapies for neuroendocrine prostate cancer (NEPC) is complicated by limited knowledge of the molecular mechanisms governing NED. The paucity of acquired genomic alterations and the deregulation of epigenetic and transcription factors suggest a potential contribution from the microenvironment. In this context, whether ADT/ARPI induces stromal cells to release NED-promoting molecules and the underlying molecular networks are unestablished. Here, we utilized transgenic and transplantable mouse models and coculture experiments to unveil a novel tumor-stroma cross-talk that is able to induce NED under the pressure of androgen deprivation. Castration induced upregulation of GRP78 in tumor cells, which triggers miR29-b-mediated downregulation of the matricellular protein SPARC in the nearby stroma. SPARC downregulation enabled stromal cells to release IL6, a known inducer of NED. A drug that targets GRP78 blocked NED in castrated mice. A public, human NEPC gene expression dataset showed that Hspa5 (encoding for GRP78) positively correlates with hallmarks of NED. Finally, prostate cancer specimens from patients developing local NED after ADT showed GRP78 upregulation in tumor cells and SPARC downregulation in the stroma. These results point to GRP78 as a potential therapeutic target and to SPARC downregulation in stromal cells as a potential early biomarker of tumors undergoing NED. SIGNIFICANCE: Tumor-stroma cross-talk promotes neuroendocrine differentiation in prostate cancer in response to hormone therapy via a GRP78/SPARC/IL6 axis, providing potential therapeutic targets and biomarkers for neuroendocrine prostate cancer.

Development of a Deep-Learning Pipeline to Recognize and Characterize Macrophages in Colo-Rectal Liver Metastasis

Quantitative analysis of Tumor Microenvironment (TME) provides prognostic and predictive information in several human cancers but, with few exceptions, it is not performed in daily clinical practice since it is extremely time-consuming. We recently showed that the morphology of Tumor Associated Macrophages (TAMs) correlates with outcome in patients with Colo-Rectal Liver Metastases (CLM). However, as for other TME components, recognizing and characterizing hundreds of TAMs in a single histopathological slide is unfeasible. To fasten this process, we explored a deep-learning based solution. We tested three Convolutional Neural Networks (CNNs), namely UNet, SegNet and DeepLab-v3, with three different segmentation strategies, semantic segmentation, pixel penalties and instance segmentation. The different experiments are compared according to the Intersection over Union (IoU), a metric describing the similarity between what CNN predicts as TAM and the ground truth, and the Symmetric Best Dice (SBD), which indicates the ability of CNN to separate different TAMs. UNet and SegNet showed intrinsic limitations in discriminating single TAMs (highest SBD 61.34±2.21), whereas DeepLab-v3 accurately recognized TAMs from the background (IoU 89.13±3.85) and separated different TAMs (SBD 79.00±3.72). This deep-learning pipeline to recognize TAMs in digital slides will allow the characterization of TAM-related metrics in the daily clinical practice, allowing the implementation of prognostic tools.

Glufosinate constrains synchronous and metachronous metastasis by promoting anti-tumor macrophages

Glutamine synthetase (GS) generates glutamine from glutamate and controls the release of inflammatory mediators. In macrophages, GS activity, driven by IL10, associates to the acquisition of M2-like functions. Conditional deletion of GS in macrophages inhibits metastasis by boosting the formation of anti-tumor, M1-like, tumor-associated macrophages (TAMs). From this basis, we evaluated the pharmacological potential of GS inhibitors in targeting metastasis, identifying glufosinate as a specific human GS inhibitor. Glufosinate was tested in both cultured macrophages and on mice bearing metastatic lung, skin and breast cancer. We found that glufosinate rewires macrophages toward an M1-like phenotype both at the primary tumor and metastatic site, countering immunosuppression and promoting vessel sprouting. This was also accompanied to a reduction in cancer cell intravasation and extravasation, leading to synchronous and metachronous metastasis growth inhibition, but no effects on primary tumor growth. Glufosinate treatment was well-tolerated, without liver and brain toxicity, nor hematopoietic defects. These results identify GS as a druggable enzyme to rewire macrophage functions and highlight the potential of targeting metabolic checkpoints in macrophages to treat cancer metastasis.

Amyloid aggregates accumulate in melanoma metastasis modulating YAP activity

Melanoma progression is generally associated with increased transcriptional activity mediated by the Yes-associated protein (YAP). Mechanical signals from the extracellular matrix are sensed by YAP, which then activates the expression of proliferative genes, promoting melanoma progression and drug resistance. Which extracellular signals induce mechanotransduction, and how this is mediated, is not completely understood. Here, using secretome analyses, we reveal the extracellular accumulation of amyloidogenic proteins, i.e. premelanosome protein (PMEL), in metastatic melanoma, together with proteins that assist amyloid maturation into fibrils. We also confirm the accumulation of amyloid-like aggregates, similar to those detected in Alzheimer disease, in metastatic cell lines, as well as in human melanoma biopsies. Mechanistically, beta-secretase 2 (BACE2) regulates the maturation of these aggregates, which in turn induce YAP activity. We also demonstrate that recombinant PMEL fibrils are sufficient to induce mechanotransduction, triggering YAP signaling. Finally, we demonstrate that BACE inhibition affects cell proliferation and increases drug sensitivity, highlighting the importance of amyloids for melanoma survival, and the use of beta-secretase inhibitors as potential therapeutic approach for metastatic melanoma.

Assessing predictors for new post translational modification sites: A case study on hydroxylation

Post-translational modification (PTM) sites have become popular for predictor development. However, with the exception of phosphorylation and a handful of other examples, PTMs suffer from a limited number of available training examples and sparsity in protein sequences. Here, proline hydroxylation is taken as an example to compare different methods and evaluate their performance on new experimentally determined sites. As a guide for effective experimental design, predictors require both high specificity and sensitivity. However, the self-reported performance may often not be indicative of prediction quality and detection of new sites is not guaranteed. We have benchmarked seven published hydroxylation site predictors on two newly constructed independent datasets. The self-reported performance is found to widely overestimate the real accuracy measured on independent datasets. No predictor performs better than random on new examples, indicating the refined models do not sufficiently generalize to detect new sites. The number of false positives is high and precision low, in particular for non-collagen proteins whose motifs are not conserved. As hydroxylation site predictors do not generalize for new data, caution is advised when using PTM predictors in the absence of independent evaluations, in particular for highly specific sites involved in signalling.

Machine learning methods are extensively used by biologists to design and interpret experiments. Predictors which take the only sequence as input are of particular interest due to the large amount of available sequence data and high self-reported performance. In this work, we evaluated post-translational modification (PTM) predictors for hydroxylation sites and found that they perform no better than random, in strong contrast to performances reported in their original publications. PTMs are chemical amino acid alterations providing the cell with conditional mechanisms to fine tune protein function, regulating complex biological processes such as signalling and cell cycle. Hydroxylation sites are a good PTM test case due to the availability of a range of predictors and an abundance of newly experimentally detected modification sites. Poor performances in our results highlight the overlooked problem of predicting PTMs when best practices are not followed and training data are likely incomplete. Experimentalists should be careful when using PTM predictors blindly and more independent assessments are needed to establish their usefulness in practice.

Long non-coding RNA uc.291 controls epithelial differentiation by interfering with the ACTL6A/BAF complex

The mechanisms that regulate the switch between epidermal progenitor state and differentiation are not fully understood. Recent findings indicate that the chromatin remodelling BAF complex (Brg1-associated factor complex or SWI/SNF complex) and the transcription factor p63 mutually recruit one another to open chromatin during epidermal differentiation. Here, we identify a long non-coding transcript that includes an ultraconserved element, uc.291, which physically interacts with ACTL6A and modulates chromatin remodelling to allow differentiation. Loss of uc.291 expression, both in primary keratinocytes and in three-dimensional skin equivalents, inhibits differentiation as indicated by epidermal differentiation complex genes down-regulation. ChIP experiments reveal that upon uc.291 depletion, ACTL6A is bound to the differentiation gene promoters and inhibits BAF complex targeting to induce terminal differentiation genes. In the presence of uc.291, the ACTL6A inhibitory effect is released, allowing chromatin changes to promote the expression of differentiation genes. Thus, uc.291 interacts with ACTL6A to modulate chromatin remodelling activity, allowing the transcription of late differentiation genes.

HOPS/TMUB1 retains p53 in the cytoplasm and sustains p53-dependent mitochondrial apoptosis

Apoptotic signalling by p53 occurs at both transcriptional and non-transcriptional levels, as p53 may act as a direct apoptogenic stimulus via activation of the intrinsic mitochondrial pathway. HOPS is a highly conserved, ubiquitously expressed shuttling protein with an ubiquitin-like domain. We generated Hops-/- mice and observed that they are viable with no apparent phenotypic defects. However, when treated with chemotherapeutic agents, Hops-/- mice display a significant reduction in apoptosis, suggesting an impaired ability to respond to genotoxic stressors. We show that HOPS acts as a regulator of cytoplasmic p53 levels and function. By binding p53, HOPS inhibits p53 proteasomal degradation and favours p53 recruitment to mitochondria and apoptosis induction. By interfering with importin α, HOPS further increases p53 cytoplasmic levels. Thus, HOPS promotes the p53-dependent mitochondrial apoptosis pathway by preserving cytoplasmic p53 from both degradation and nuclear uptake.

Activation of Latent HIV-1 T Cell Reservoirs with a Combination of Innate Immune and Epigenetic Regulators

The presence of T cell reservoirs in which human immunodeficiency virus (HIV) establishes latency by integrating into the host genome represents a major obstacle to an HIV cure and has prompted the development of strategies aimed at the eradication of HIV from latently infected cells. The "shock-and-kill" strategy is one of the most pursued approaches to the elimination of viral reservoirs. Although several latency-reversing agents (LRAs) have shown promising reactivation activity, they have failed to eliminate the cellular reservoir. In this study, we evaluated a novel immune system-mediated approach to clearing the HIV reservoir, based on a combination of innate immune stimulation and epigenetic reprogramming. The combination of the STING agonist cGAMP (cyclic GMP-AMP) and the FDA-approved histone deacetylase inhibitor resminostat resulted in a significant increase in HIV proviral reactivation and specific apoptosis in HIV-infected cells in vitro Reductions in the proportion of HIV-harboring cells and the total amount of HIV DNA were also observed in CD4+ central memory T (TCM) cells, a primary cell model of latency, where resminostat alone or together with cGAMP induced high levels of selective cell death. Finally, high levels of cell-associated HIV RNA were detected ex vivo in peripheral blood mononuclear cells (PBMCs) and CD4+ T cells from individuals on suppressive antiretroviral therapy (ART). Although synergism was not detected in PBMCs with the combination, viral RNA expression was significantly increased in CD4+ T cells. Collectively, these results represent a promising step toward HIV eradication by demonstrating the potential of innate immune activation and epigenetic modulation for reducing the viral reservoir and inducing specific death of HIV-infected cells.IMPORTANCE One of the challenges associated with HIV-1 infection is that despite antiretroviral therapies that reduce HIV-1 loads to undetectable levels, proviral DNA remains dormant in a subpopulation of T lymphocytes. Numerous strategies to clear residual virus by reactivating latent virus and eliminating the reservoir of HIV-1 (so-called "shock-and-kill" strategies) have been proposed. In the present study, we use a combination of small molecules that activate the cGAS-STING antiviral innate immune response (the di-cyclic nucleotide cGAMP) and epigenetic modulators (histone deacetylase inhibitors) that induce reactivation and HIV-infected T cell killing in cell lines, primary T lymphocytes, and patient samples. These studies represent a novel strategy for HIV eradication by reducing the viral reservoir and inducing specific death of HIV-infected cells.

Diflunisal targets the HMGB1/CXCL12 heterocomplex and blocks immune cell recruitment

Extracellular HMGB1 triggers inflammation following infection or injury and supports tumorigenesis in inflammation-related malignancies. HMGB1 has several redox states: reduced HMGB1 recruits inflammatory cells to injured tissues forming a heterocomplex with CXCL12 and signaling via its receptor CXCR4; disulfide-containing HMGB1 binds to TLR4 and promotes inflammatory responses. Here we show that diflunisal, an aspirin-like nonsteroidal anti-inflammatory drug (NSAID) that has been in clinical use for decades, specifically inhibits in vitro and in vivo the chemotactic activity of HMGB1 at nanomolar concentrations, at least in part by binding directly to both HMGB1 and CXCL12 and disrupting their heterocomplex. Importantly, diflunisal does not inhibit TLR4-dependent responses. Our findings clarify the mode of action of diflunisal and open the way to the rational design of functionally specific anti-inflammatory drugs.

Redundancy and Complementarity between ERAP1 and ERAP2 Revealed by their Effects on the Behcet's Disease-associated HLA-B*51 Peptidome

The endoplasmic reticulum aminopeptidases ERAP1 and ERAP2 trim peptides to be loaded onto HLA molecules, including the main risk factor for Behçet's disease HLA-B*51. ERAP1 is also a risk factor among HLA-B*51-positive individuals, whereas no association is known with ERAP2. This study addressed the mutual relationships between both enzymes in the processing of an HLA-bound peptidome, interrogating their differential association with Behçet's disease. CRISPR/Cas9 was used to generate knock outs of ERAP1, ERAP2 or both from transfectant 721.221-HLA-B*51:01 cells. The surface expression of HLA-B*51 was reduced in all cases. The effects of depleting each or both enzymes on the B*51:01 peptidome were analyzed by quantitative label-free mass spectrometry. Substantial quantitative alterations of peptide length, subpeptidome balance, N-terminal residue usage, affinity and presentation of noncanonical ligands were observed. These effects were often different in the presence or absence of the other enzyme, revealing their mutual dependence. In the absence of ERAP1, ERAP2 showed similar and significant processing of B*51:01 ligands, indicating functional redundancy. The high overlap between the peptidomes of wildtype and double KO cells indicates that a large majority of B*51:01 ligands are present in the ER even in the absence of ERAP1/ERAP2. These results indicate that both enzymes have distinct, but complementary and partially redundant effects on the B*51:01 peptidome, leading to its optimization and maximal surface expression. The distinct effects of both enzymes on the HLA-B*51 peptidome provide a basis for their differential association with Behçet's disease and suggest a pathogenetic role of the B*51:01 peptidome.

Phosphorylation of Human Papillomavirus Type 16 L2 Contributes to Efficient Virus Infectious Entry

The human papillomavirus (HPV) capsid comprises two viral proteins, L1 and L2, with the L2 component being essential to ensure efficient endocytic transport of incoming viral genomes. Several studies have previously reported that L1 and L2 are posttranslationally modified, but it is uncertain whether these modifications affect HPV infectious entry. Using a proteomic screen, we identified a highly conserved phospho-acceptor site on the HPV-16 and bovine papillomavirus 1 (BPV-1) L2 proteins. The phospho-modification of L2 and its presence in HPV pseudovirions (PsVs) were confirmed using anti-phospho-L2-specific antibodies. Mutation of the phospho-acceptor sites of both HPV-16 and BPV-1 L2 resulted in the production of infectious virus particles, with no differences in efficiencies of packaging the reporter DNA. However, these mutated PsVs showed marked defects in infectious entry. Further analysis revealed a defect in uncoating, characterized by a delay in the exposure of a conformational epitope on L1 that indicates capsid uncoating. This uncoating defect was accompanied by a delay in the proteolysis of both L1 and L2 in mutated HPV-16 PsVs. Taken together, these studies indicate that phosphorylation of L2 during virus assembly plays an important role in optimal uncoating of virions during infection, suggesting that phosphorylation of the viral capsid proteins contributes to infectious entry.IMPORTANCE The papillomavirus L2 capsid protein plays an essential role in infectious entry, where it directs the successful trafficking of incoming viral genomes to the nucleus. However, nothing is known about how potential posttranslational modifications may affect different aspects of capsid assembly or infectious entry. In this study, we report the first phospho-specific modification of the BPV-1 and HPV-16 L2 capsid proteins. The phospho-acceptor site is very highly conserved across multiple papillomavirus types, indicating a highly conserved function within the L2 protein and the viral capsid. We show that this modification plays an essential role in infectious entry, where it modulates susceptibility of the incoming virus to capsid disassembly. These studies therefore define a completely new means of regulating the papillomavirus L2 proteins, a regulation that optimizes endocytic processing and subsequent completion of the infectious entry pathway.

Emerging roles of telomeric chromatin alterations in cancer

Telomeres, the nucleoprotein structures that cap the ends of eukaryotic chromosomes, play important and multiple roles in tumorigenesis. Functional telomeres need the establishment of a protective chromatin structure based on the interplay between the specific complex named shelterin and a tight nucleosomal organization. Telomere shortening in duplicating somatic cells leads eventually to the destabilization of the telomere capping structure and to the activation of a DNA damage response (DDR) signaling. The final outcome of this process is cell replicative senescence, which constitute a protective barrier against unlimited proliferation. Cells that can bypass senescence checkpoint continue to divide until a second replicative checkpoint, crisis, characterized by chromosome fusions and rearrangements leading to massive cell death by apoptosis. During crisis telomere dysfunctions can either inhibit cell replication or favor tumorigenesis by the accumulation of chromosomal rearrangements and neoplastic mutations. The acquirement of a telomere maintenance mechanism allows fixing the aberrant phenotype, and gives the neoplastic cell unlimited replicative potential, one of the main hallmarks of cancer.Despite the crucial role that telomeres play in cancer development, little is known about the epigenetic alterations of telomeric chromatin that affect telomere protection and are associated with tumorigenesis. Here we discuss the current knowledge on the role of telomeric chromatin in neoplastic transformation, with a particular focus on H3.3 mutations in alternative lengthening of telomeres (ALT) cancers and sirtuin deacetylases dysfunctions.

Early immune modulation by single-agent trastuzumab as a marker of trastuzumab benefit

BACKGROUND

Optimising the selection of HER2-targeted regimens by identifying subsets of HER2-positive breast cancer (BC) patients who need more or less therapy remains challenging. We analysed BC samples before and after treatment with 1 cycle of trastuzumab according to the response to trastuzumab.

METHODS

Gene expression profiles of pre- and post-treatment tumour samples from 17 HER2-positive BC patients were analysed on the Illumina platform. Tumour-associated immune pathways and blood counts were analysed with regard to the response to trastuzumab. HER2-positive murine models with differential responses to trastuzumab were used to reproduce and better characterise these data.

RESULTS

Patients who responded to single-agent trastuzumab had basal tumour biopsies that were enriched in immune pathways, particularly the MHC-II metagene. One cycle of trastuzumab modulated the expression levels of MHC-II genes, which increased in patients who had a complete response on treatment with trastuzumab and chemotherapy. Trastuzumab increased the MHC-II-positive cell population, primarily macrophages, only in the tumour microenvironment of responsive mice. In patients who benefited from complete trastuzumab therapy and in mice that harboured responsive tumours circulating neutrophil levels declined, but this cell subset rose in nonresponsive tumours.

CONCLUSIONS

Short treatment with trastuzumab induces local and systemic immunomodulation that is associated with clinical outcomes.

SPOP mutation leads to genomic instability in prostate cancer

Genomic instability is a fundamental feature of human cancer often resulting from impaired genome maintenance. In prostate cancer, structural genomic rearrangements are a common mechanism driving tumorigenesis. However, somatic alterations predisposing to chromosomal rearrangements in prostate cancer remain largely undefined. Here, we show that SPOP, the most commonly mutated gene in primary prostate cancer modulates DNA double strand break (DSB) repair, and that SPOP mutation is associated with genomic instability. In vivo, SPOP mutation results in a transcriptional response consistent with BRCA1 inactivation resulting in impaired homology-directed repair (HDR) of DSB. Furthermore, we found that SPOP mutation sensitizes to DNA damaging therapeutic agents such as PARP inhibitors. These results implicate SPOP as a novel participant in DSB repair, suggest that SPOP mutation drives prostate tumorigenesis in part through genomic instability, and indicate that mutant SPOP may increase response to DNA-damaging therapeutics.

Transport of soluble proteins through the Golgi occurs by diffusion via continuities across cisternae

The mechanism of transport through the Golgi complex is not completely understood, insofar as no single transport mechanism appears to account for all of the observations. Here, we compare the transport of soluble secretory proteins (albumin and α1-antitrypsin) with that of supramolecular cargoes (e.g., procollagen) that are proposed to traverse the Golgi by compartment progression-maturation. We show that these soluble proteins traverse the Golgi much faster than procollagen while moving through the same stack. Moreover, we present kinetic and morphological observations that indicate that albumin transport occurs by diffusion via intercisternal continuities. These data provide evidence for a transport mechanism that applies to a major class of secretory proteins and indicate the co-existence of multiple intra-Golgi trafficking modes.