Cytokeratin-17 expression is commonly observed in keratinocytic skin tumours and controls tissue homeostasis impacting HPV protein expression.

BACKGROUND: The structured expression of several keratins in the skin is associated with differentiation status of the epidermal layers, whereas others are upregulated only during wound healing, in skin disorders and in cancers. One of these stress keratins, K17, is correlated with poor prognosis in various cancer types and its loss has been shown to decelerate tumour growth. K17 expression can also be detected in cutaneous squamous cell carcinomas (SCCs), where UV-irradiation and infection with cutaneous human papillomaviruses (HPVs) are important co-factors. It was previously reported that K17 is upregulated in papillomavirus (PV)-induced benign skin lesions in mice and induces an immunological status that is beneficial for tumour growth. OBJECTIVES: In order to investigate whether K17 upregulation is induced by PVs, we analysed K17 levels in skin tumour specimens of different animal models and humans. METHODS: Various immunofluorescence stainings were performed to identify K17 expression as well as levels of E-Cadherin, vimentin and CD271. Tissues were further analysed by PCRs, qPCRs and ELISA to control for PV activity. K17knockdown cells were generated and effects on viral life cycle were investigated by infection assays, qPCR and Western blotting. RESULTS: We could show that K17 is commonly expressed in skin tumours and that its presence is not directly linked to viral oncoprotein expression. Rather, K17 expression seems to be a marker of epithelial differentiation and its absence in tumour tissue is associated with an epithelial-to-mesenchymal transition. We further showed that the absence of K17 in skin tumours increases markers of cancer stem-like cells and negatively affects viral protein synthesis. CONCLUSIONS: Collectively, our data indicate that K17 expression is a common feature in skin tumourigenesis. While it is not primarily targeted by PV oncoproteins, our in vivo and in vitro data suggest that it is an important regulator of epithelial differentiation and thus may play a role in controlling viral protein synthesis.

Spatial tissue proteomics reveals distinct landscapes of heterogeneity in cutaneous papillomavirus-induced keratinocyte carcinomas.

Infection with certain cutaneous human papillomaviruses (HPV), in conjunction with chronic ultraviolet (UV) exposure, are the major cofactors of non-melanoma skin cancer (NMSC), the most frequent cancer type worldwide. Cutaneous squamous cell carcinomas (SCCs) as well as tumors in general represent three-dimensional entities determined by both temporal and spatial constraints. Whole tissue proteomics is a straightforward approach to understand tumorigenesis in better detail, but studies focusing on different progression states toward a dedifferentiated SCC phenotype on a spatial level are rare. Here, we applied an innovative proteomic workflow on formalin-fixed, paraffin-embedded (FFPE) epithelial tumors derived from the preclinical animal model Mastomys coucha. This rodent is naturally infected with its genuine cutaneous papillomavirus and closely mimics skin carcinogenesis in the context of cutaneous HPV infections in humans. We deciphered cellular networks by comparing diverse epithelial tissues with respect to their differentiation level and infection status. Our study reveals novel regulatory proteins and pathways associated with virus-induced tumor initiation and progression of SCCs. This approach provides the basis to better comprehend the multistep process of skin carcinogenesis.

Decrypting Integrins by Mixed-Solvent Molecular Dynamics Simulations.

Integrins are a family of α/ß heterodimeric cell surface adhesion receptors which are capable of transmitting signals bidirectionally across membranes. They are known for their therapeutic potential in a wide range of diseases. However, the development of integrin-targeting medications has been impacted by unexpected downstream effects including unwanted agonist-like effects. Allosteric modulation of integrins is a promising approach to potentially overcome these limitations. Applying mixed-solvent molecular dynamics (MD) simulations to integrins, the current study uncovers hitherto unknown allosteric sites within the integrin α I domains of LFA-1 (αLß2; CD11a/CD18), VLA-1 (α1ß1; CD49a/CD29), and Mac-1 (αMß2, CD11b/CD18). We show that these pockets are putatively accessible to small-molecule modulators. The findings reported here may provide opportunities for the design of novel allosteric integrin inhibitors lacking the unwanted agonism observed with earlier as well as current integrin-targeting drugs.

Allosteric targeting resolves limitations of earlier LFA-1 directed modalities.

Integrins are a family of cell surface receptors well-recognized for their therapeutic potential in a wide range of diseases. However, the development of integrin targeting medications has been impacted by unexpected downstream effects, reflecting originally unforeseen interference with the bidirectional signalling and cross-communication of integrins. We here selected one of the most severely affected target integrins, the integrin lymphocyte function-associated antigen-1 (LFA-1, αLß2, CD11a/CD18), as a prototypic integrin to systematically assess and overcome these known shortcomings. We employed a two-tiered ligand-based virtual screening approach to identify a novel class of allosteric small molecule inhibitors targeting this integrin's αI domain. The newly discovered chemical scaffold was derivatized, yielding potent bis-and tris-aryl-bicyclic-succinimides which inhibit LFA-1 in vitro at low nanomolar concentrations. The characterisation of these compounds in comparison to earlier LFA-1 targeting modalities established that the allosteric LFA-1 inhibitors (i) are devoid of partial agonism, (ii) selectively bind LFA-1 versus other integrins, (iii) do not trigger internalization of LFA-1 itself or other integrins and (iv) display oral availability. This profile differentiates the new generation of allosteric LFA-1 inhibitors from previous ligand mimetic-based LFA-1 inhibitors and anti-LFA-1 antibodies, and is projected to support novel immune regulatory regimens selectively targeting the integrin LFA-1. The rigorous computational and experimental assessment schedule described here is designed to be adaptable to the preclinical discovery and development of novel allosterically acting compounds targeting integrins other than LFA-1, providing an exemplary approach for the early characterisation of next generation integrin inhibitors.

TRIM67 drives tumorigenesis in oligodendrogliomas through Rho GTPase-dependent membrane blebbing.

BACKGROUND: IDH mutant gliomas are grouped into astrocytomas or oligodendrogliomas depending on the codeletion of chromosome arms 1p and 19q. Although the genomic alterations of IDH mutant gliomas have been well described, transcriptional changes unique to either tumor type have not been fully understood. Here, we identify Tripartite Motif Containing 67 (TRIM67), an E3 ubiquitin ligase with essential roles during neuronal development, as an oncogene distinctly upregulated in oligodendrogliomas. METHODS: We used several cell lines, including patient-derived oligodendroglioma tumorspheres, to knock down or overexpress TRIM67. We coupled high-throughput assays, including RNA sequencing, total lysate-mass spectrometry (MS), and coimmunoprecipitation (co-IP)-MS with functional assays including immunofluorescence (IF) staining, co-IP, and western blotting (WB) to assess the in vitro phenotype associated with TRIM67. Patient-derived oligodendroglioma tumorspheres were orthotopically implanted in mice to determine the effect of TRIM67 on tumor growth and survival. RESULTS: TRIM67 overexpression alters the abundance of cytoskeletal proteins and induces membrane bleb formation. TRIM67-associated blebbing was reverted with the nonmuscle class II myosin inhibitor blebbistatin and selective ROCK inhibitor fasudil. NOGO-A/Rho GTPase/ROCK2 signaling is altered upon TRIM67 ectopic expression, pointing to the underlying mechanism for TRIM67-induced blebbing. Phenotypically, TRIM67 expression resulted in higher cell motility and reduced cell adherence. In orthotopic implantation models of patient-derived oligodendrogliomas, TRIM67 accelerated tumor growth, reduced overall survival, and led to increased vimentin expression at the tumor margin. CONCLUSIONS: Taken together, our results demonstrate that upregulated TRIM67 induces blebbing-based rounded cell morphology through Rho GTPase/ROCK-mediated signaling thereby contributing to glioma pathogenesis.

Next generation L2-based HPV vaccines cross-protect against cutaneous papillomavirus infection and tumor development.

Licensed L1-VLP-based immunizations against high-risk mucosal human papillomavirus (HPV) types have been a great success in reducing anogenital cancers, although they are limited in their cross-protection against HPV types not covered by the vaccine. Further, their utility in protection against cutaneous HPV types, of which some contribute to non-melanoma skin cancer (NMSC) development, is rather low. Next generation vaccines achieve broadly cross-protective immunity against highly conserved sequences of L2. In this exploratory study, we tested two novel HPV vaccine candidates, HPV16 RG1-VLP and CUT-PANHPVAX, in the preclinical natural infection model Mastomys coucha. After immunization with either vaccines, a mock control or MnPV L1-VLPs, the animals were experimentally infected and monitored. Besides vaccine-specific seroconversion against HPV L2 peptides, the animals also developed cross-reactive antibodies against the cutaneous Mastomys natalensis papillomavirus (MnPV) L2, which were cross-neutralizing MnPV pseudovirions in vitro. Further, both L2-based vaccines also conferred in vivo protection as the viral loads in plucked hair after experimental infection were lower compared to mock-vaccinated control animals. Importantly, the formation of neutralizing antibodies, whether directed against L1-VLPs or L2, was able to prevent skin tumor formation and even microscopical signs of MnPV infection in the skin. For the first time, our study shows the proof-of-principle of next generation L2-based vaccines even across different PV genera in an infection animal model with its genuine PV. It provides fundamental insights into the humoral immunity elicited by L2-based vaccines against PV-induced skin tumors, with important implications to the design of next generation HPV vaccines.

Isoforms of the Papillomavirus Major Capsid Protein Differ in Their Ability to Block Viral Spread and Tumor Formation.

Notably, the majority of papillomaviruses associated with a high cancer risk have the potential to translate different isoforms of the L1 major capsid protein. In an infection model, the cutaneous Mastomys natalensis papillomavirus (MnPV) circumvents the humoral immune response of its natural host by first expressing a 30 amino acid extended L1 isoform (L1LONG). Although inducing a robust seroconversion, the raised antibodies are not neutralizing in vitro. In contrast, neutralizing antibodies induced by the capsid-forming isoform (L1SHORT) appear delayed by several months. We now provide evidence that, although L1LONG vaccination showed a strong seroconversion, these antibodies were not protective. As a consequence, virus-free animals subsequently infected with MnPV still accumulated high numbers of transcriptionally active viral genomes, ultimately leading to skin tumor formation. In contrast, vaccination with L1SHORT was completely protective. This shows that papillomavirus L1LONG expression is a unique strategy to escape from antiviral immune surveillance.

Radiotherapy orchestrates natural killer cell dependent antitumor immune responses through CXCL8.

Radiotherapy is a mainstay cancer therapy whose antitumor effects partially depend on T cell responses. However, the role of Natural Killer (NK) cells in radiotherapy remains unclear. Here, using a reverse translational approach, we show a central role of NK cells in the radiation-induced immune response involving a CXCL8/IL-8-dependent mechanism. In a randomized controlled pancreatic cancer trial, CXCL8 increased under radiotherapy, and NK cell positively correlated with prolonged overall survival. Accordingly, NK cells preferentially infiltrated irradiated pancreatic tumors and exhibited CD56dim-like cytotoxic transcriptomic states. In experimental models, NF-κB and mTOR orchestrated radiation-induced CXCL8 secretion from tumor cells with senescence features causing directional migration of CD56dim NK cells, thus linking senescence-associated CXCL8 release to innate immune surveillance of human tumors. Moreover, combined high-dose radiotherapy and adoptive NK cell transfer improved tumor control over monotherapies in xenografted mice, suggesting NK cells combined with radiotherapy as a rational cancer treatment strategy.

Anti-αLß2 antibodies reveal novel endocytotic cross-modulatory functionality.

BACKGROUND AND PURPOSE: Antibodies targeting cell surface receptors are considered to enable highly selective therapeutic interventions for immune disorders and cancer. Their biological profiles are found, generally, to represent the net effects of antibody-target interactions. The former therapeutic anti-integrin αLß2 antibody efalizumab seems to defeat this paradigm by eliciting, via mechanisms currently unknown, much broader effects than would be predicted based on its target specificity. EXPERIMENTAL APPROACH: To elucidate the mechanisms behind these broad effects, we investigated in primary human lymphocytes in vitro the effects of anti-αLß2 antibodies on the expression of αLß2 as well as unrelated α4 integrins, in comparison to Fab fragments and small-molecule inhibitors. KEY RESULTS: We demonstrate that anti-αLß2 mAbs directly induce the internalization of α4 integrins. The endocytotic phenomenon is a direct consequence of their antibody nature. It is inhibited when monovalent Fab fragments or small-molecule inhibitors are used. It is independent of crosslinking via anti-Fc mAbs and of αLß2 activation. The cross-modulatory effect is unidirectional and not observed in a similar fashion with the α4 integrin antibody natalizumab. CONCLUSION AND IMPLICATIONS: The present study identifies endocytotic cross-modulation as a hitherto unknown non-canonical functionality of anti-αLß2 antibodies. This cross-modulation has the potential to fundamentally alter an antibody's benefit risk profile, as evident with efalizumab. The newly described phenomenon may be of relevance to other therapeutic antibodies targeting cluster-forming receptors. Thus, pharmacologists should be cognizant of this action when investigating such antibodies.

Downstream effect profiles discern different mechanisms of integrin αLß2 inhibition.

The integrin leucocyte function-associated antigen-1 (αLß2, LFA-1) plays crucial roles in T cell adhesion, migration and immunological synapse (IS) formation. Consequently, αLß2 is an important therapeutic target in autoimmunity. Three major classes of αLß2 inhibitors with distinct modes of action have been described to date: Monoclonal antibodies (mAbs), small molecule α/ß I allosteric and small molecule α I allosteric inhibitors. The objective of this study was to systematically compare these three modes of αLß2 inhibition for their αLß2 inhibitory as well as their potential agonist-like effects. All inhibitors assessed were found to potently block αLß2-mediated leucocyte adhesion. None of the inhibitors induced ZAP70 phosphorylation, indicating absence of agonistic outside-in signalling. Paradoxically, however, the α/ß I allosteric inhibitor XVA143 induced conformational changes within αLß2 characteristic for an intermediate affinity state. This effect was not observed with the α I allosteric inhibitor LFA878 or the anti-αLß2 mAb efalizumab. On the other hand, efalizumab triggered the unscheduled internalization of αLß2 in CD4+ and CD8+ T cells while LFA878 and XVA143 did not affect or only mildly reduced αLß2 surface expression, respectively. Moreover, efalizumab, in contrast to the small molecule inhibitors, disturbed the fine-tuned internalization/recycling of engaged TCR/CD3, concomitantly decreasing ZAP70 expression levels. In conclusion, different modes of αLß2 inhibition are associated with fundamentally different biologic effect profiles. The differential established here is expected to provide important translational guidance as novel αLß2 inhibitors will be advanced from bench to bedside.

The Swiss Society of Experimental Pharmacology in Times of Change.

Experimental pharmacology is undergoing fundamental changes. This article describes the challenges and opportunities associated with these changes from the perspective of the Swiss Society of Pharmacology (SSEP), the society which aims to advance experimental pharmacology in Switzerland and abroad.

Quality expectations and tolerance limits of trial master files (TMF) - Developing a risk-based approach for quality assessments of TMFs.

This article addresses the question of when a trial master file (TMF) can be considered sufficiently accurate and complete: What attributes does the TMF need to have so that a clinical trial can be adequately reconstructed from documented data and procedures? Clinical trial sponsors face significant challenges in assembling the TMF, especially when dealing with large, international, multicenter studies; despite all newly introduced archiving techniques it is becoming more and more difficult to ensure that the TMF is complete. This is directly reflected in the number of inspection findings reported and published by the EMA in 2014. Based on quality risk management principles in clinical trials the authors defined the quality expectations for the different document types in a TMF and furthermore defined tolerance limits for missing documents. This publication provides guidance on what type of documents and processes are most important, and in consequence, indicates on which documents and processes trial team staff should focus in order to achieve a high-quality TMF. The members of this working group belong to the CQAG Group (Clinical Quality Assurance Germany) and are QA (quality assurance) experts (auditors or compliance functions) with long-term experience in the practical handling of TMFs.

A novel multi-parameter assay to dissect the pharmacological effects of different modes of integrin αLß2 inhibition in whole blood.

BACKGROUND AND PURPOSE: The integrin αLß2 plays central roles in leukocyte adhesion and T cell activation, rendering αLß2 an attractive therapeutic target. Compounds with different modes of αLß2 inhibition are in development, currently. Consequently, there is a foreseeable need for bedside assays, which allow assessment of the different effects of diverse types of αLß2 inhibitors in the peripheral blood of treated patients. EXPERIMENTAL APPROACH: Here, we describe a flow cytometry-based technology that simultaneously quantitates αLß2 conformational change upon inhibitor binding, αLß2 expression and T cell activation at the single-cell level in human blood. Two classes of allosteric low MW inhibitors, designated α I and α/ß I allosteric αLß2 inhibitors, were investigated. The first application revealed intriguing inhibitor class-specific profiles. KEY RESULTS: Half-maximal inhibition of T cell activation was associated with 80% epitope loss induced by α I allosteric inhibitors and with 40% epitope gain induced by α/ß I allosteric inhibitors. This differential establishes that inhibitor-induced αLß2 epitope changes do not directly predict the effect on T cell activation. Moreover, we show here for the first time that α/ß I allosteric inhibitors, in contrast to α I allosteric inhibitors, provoked partial downmodulation of αLß2, revealing a novel property of this inhibitor class. CONCLUSIONS AND IMPLICATIONS: The multi-parameter whole blood αLß2 assay described here may enable therapeutic monitoring of αLß2 inhibitors in patients' blood. The assay dissects differential effect profiles of different classes of αLß2 inhibitors.

Cell adhesion assays.

Standard adhesion assays measure cell binding either to immobilized ligands or to cell monolayers in flat-well microtiter plates under static conditions. Typically, these test systems require several washing steps to separate adherent from nonadherent cells. Here, we describe an adhesion assay which avoids these washing steps by employing V-bottom 96-well plates. In this assay, fluorescently labeled leukocytes are allowed to adhere to V-well plates coated with soluble ligand for a fixed time. Thereafter, centrifugal force is applied to separate adherent cells from nonadherent cells. Nonadherent cells accumulate in the nadir of the V-shaped wells and are quantified using a fluorometer with a narrow aperture. This simple and reproducible method has been validated with different classes of adhesion molecule families (selectins and integrins) and is adaptable to several other adhesive interactions. The assay format is suitable for screening applications and may also be used for diagnostic testing. The receptor/ligand interaction chosen as an example to describe the assay methodology is the interaction between the integrin lymphocyte function-associated molecule-1 (LFA-1, α(L)ß(2)) and intercellular adhesion molecule-1 (ICAM-1).

The C-terminal αI domain linker as a critical structural element in the conformational activation of αI integrins.

The activation of α/ß heterodimeric integrins is the result of highly coordinated rearrangements within both subunits. The molecular interactions between the two subunits, however, remain to be characterized. In this study, we use the integrin α(L)ß(2) to investigate the functional role of the C-linker polypeptide that connects the C-terminal end of the inserted (I) domain with the ß-propeller domain on the α subunit and is located at the interface with the ßI domain of the ß chain. We demonstrate that shortening of the C-linker by eight or more amino acids results in constitutively active α(L)ß(2) in which the αI domain is no longer responsive to the regulation by the ßI domain. Despite this intersubunit uncoupling, both I domains remain individually sensitive to intrasubunit conformational changes induced by allosteric modulators. Interestingly, the length and not the sequence of the C-linker appears to be critical for its functionality in α/ß intersubunit communication. Using two monoclonal antibodies (R7.1 and CBR LFA-1/1) we further demonstrate that shortening of the C-linker results in the gradual loss of combinational epitopes that require both the αI and ß-propeller domains for full reactivity. Taken together, our findings highlight the role of the C-linker as a spring-like element that allows relaxation of the αI domain in the resting state and controlled tension of the αI domain during activation, exerted by the ß chain.

A heterozygous mutation of the insulin-like growth factor-I receptor causes retention of the nascent protein in the endoplasmic reticulum and results in intrauterine and postnatal growth retardation.

BACKGROUND: Mutations in the IGF-I receptor (IGF1R) gene can be responsible for intrauterine and postnatal growth disorders. OBJECTIVE: Here we report on a novel mutation in the IGF1R gene in a female patient. The aim of our study was to analyze the functional impact of this mutation. PATIENT: At birth, the girl's length was 47 cm [-1.82 sd score (SDS)], and her weight was 2250 g (-2.26 SDS). Clinical examination revealed microcephaly and retarded cognitive development. She showed no postnatal catch-up growth but had relatively high IGF-I levels (+1.83 to +2.17 SDS). RESULTS: Denaturing HPLC screening and direct DNA sequencing disclosed a heterozygous missense mutation resulting in an amino acid exchange from valine to glutamic acid at position 599 (V599E-IGF1R). Using various cell systems, we found that the V599E-IGF1R mutant was not tyrosine phosphorylated and had an impaired downstream signaling in the presence of IGF-I. Flow cytometry and live cell confocal laser scanning microscopy revealed a lack of cell surface expression due to an extensive retention of V599E-IGF1R proteins within the endoplasmic reticulum. CONCLUSION: The V599E-IGF1R mutation interferes with the receptor's trafficking path, thereby abrogating proreceptor processing and plasma membrane localization. Diminished cell surface receptor density solely expressed from the patient's wild-type allele is supposed to lead to insufficient IGF-I signaling. We hypothesize that this mechanism results in intrauterine and postnatal growth retardation of the affected patient. The reported retention of the nascent IGF1R in the endoplasmic reticulum presents a novel mechanism of IGF-I resistance.

The potent protein kinase C-selective inhibitor AEB071 (sotrastaurin) represents a new class of immunosuppressive agents affecting early T-cell activation.

There is a pressing need for immunosuppressants with an improved safety profile. The search for novel approaches to blocking T-cell activation led to the development of the selective protein kinase C (PKC) inhibitor AEB071 (sotrastaurin). In cell-free kinase assays AEB071 inhibited PKC, with K(i) values in the subnanomolar to low nanomolar range. Upon T-cell stimulation, AEB071 markedly inhibited in situ PKC catalytic activity and selectively affected both the canonical nuclear factor-kappaB and nuclear factor of activated T cells (but not activator protein-1) transactivation pathways. In primary human and mouse T cells, AEB071 treatment effectively abrogated at low nanomolar concentration markers of early T-cell activation, such as interleukin-2 secretion and CD25 expression. Accordingly, the CD3/CD28 antibody- and alloantigen-induced T-cell proliferation responses were potently inhibited by AEB071 in the absence of nonspecific antiproliferative effects. Unlike former PKC inhibitors, AEB071 did not enhance apoptosis of murine T-cell blasts in a model of activation-induced cell death. Furthermore, AEB071 markedly inhibited lymphocyte function-associated antigen-1-mediated T-cell adhesion at nanomolar concentrations. The mode of action of AEB071 is different from that of calcineurin inhibitors, and AEB071 and cyclosporine A seem to have complementary effects on T-cell signaling pathways.