Compositional complementarity between genomic RNA and coat proteins in positive-sense single-stranded RNA viruses.

During packaging in positive-sense single-stranded RNA (+ssRNA) viruses, coat proteins (CPs) interact directly with multiple regions in genomic RNA (gRNA), but the underlying physicochemical principles remain unclear. Here we analyze the high-resolution cryo-EM structure of bacteriophage MS2 and show that the gRNA/CP binding sites, including the known packaging signal, overlap significantly with regions where gRNA nucleobase-density profiles match the corresponding CP nucleobase-affinity profiles. Moreover, we show that the MS2 packaging signal corresponds to the global minimum in gRNA/CP interaction energy in the unstructured state as derived using a linearly additive model and knowledge-based nucleobase/amino-acid affinities. Motivated by this, we predict gRNA/CP interaction sites for a comprehensive set of 1082 +ssRNA viruses. We validate our predictions by comparing them with site-resolved information on gRNA/CP interactions derived in SELEX and CLIP experiments for 10 different viruses. Finally, we show that in experimentally studied systems CPs frequently interact with autologous coding regions in gRNA, in agreement with both predicted interaction energies and a recent proposal that proteins in general tend to interact with own mRNAs, if unstructured. Our results define a self-consistent framework for understanding packaging in +ssRNA viruses and implicate interactions between unstructured gRNA and CPs in the process.

Unraveling most abundant mutational signatures in head and neck cancer.

Genomic alterations are a driving force in the multistep process of head and neck cancer (HNC) and result from the interaction of exogenous environmental exposures and endogenous cellular processes. Each of these processes leaves a characteristic pattern of mutations on the tumor genome providing the unique opportunity to decipher specific signatures of mutational processes operative during HNC pathogenesis and to address their prognostic value. Computational analysis of whole exome sequencing data of the HIPO-HNC (Heidelberg Center for Personalized Oncology-head and neck cancer) (n = 83) and TCGA-HNSC (The Cancer Genome Atlas-Head and Neck Squamous Cell Carcinoma) (n = 506) cohorts revealed five common mutational signatures (Catalogue of Somatic Mutations in Cancer [COSMIC] Signatures 1, 2, 3, 13 and 16) and demonstrated their significant association with etiological risk factors (tobacco, alcohol and HPV16). Unsupervised hierarchical clustering identified four clusters (A, B, C1 and C2) of which Subcluster C2 was enriched for cases with a higher frequency of signature 16 mutations. Tumors of Subcluster C2 had significantly lower p16INK4A expression accompanied by homozygous CDKN2A deletion in almost one half of cases. Survival analysis revealed an unfavorable prognosis for patients with tumors characterized by a higher mutation burden attributed to signature 16 as well as cases in Subcluster C2. Finally, a LASSO-Cox regression model was applied to prioritize clinically relevant signatures and to establish a prognostic risk score for head and neck squamous cell carcinoma patients. In conclusion, our study provides a proof of concept that computational analysis of somatic mutational signatures is not only a powerful tool to decipher environmental and intrinsic processes in the pathogenesis of HNC, but could also pave the way to establish reliable prognostic patterns.

Malleable nature of mRNA-protein compositional complementarity and its functional significance.

It has recently been demonstrated that nucleobase-density profiles of typical mRNA coding sequences exhibit a complementary relationship with nucleobase-interaction propensity profiles of their cognate protein sequences. This finding supports the idea that the genetic code developed in response to direct binding interactions between amino acids and appropriate nucleobases, but also suggests that present-day mRNAs and their cognate proteins may be physicochemically complementary to each other and bind. Here, we computationally recode complete Methanocaldococcus jannaschii, Escherichia coli and Homo sapiens mRNA transcriptomes and analyze how much complementary matching of synonymous mRNAs can vary, while keeping protein sequences fixed. We show that for most proteins there exist cognate mRNAs that improve, but also significantly worsen the level of native matching (e.g. by 1.8 viz. 7.6 standard deviations on average for H. sapiens, respectively), with the least malleable proteins in this sense being strongly enriched in nuclear localization and DNA-binding functions. Even so, we show that the majority of recodings for most proteins result in pronounced complementarity. Our results suggest that the genetic code was designed for favorable, yet tunable compositional complementarity between mRNAs and their cognate proteins, supporting the hypothesis that the interactions between the two were an important defining element behind the code's origin.

Sequence signatures of direct complementarity between mRNAs and cognate proteins on multiple levels.

A potential connection between physico-chemical properties of mRNAs and cognate proteins, with implications concerning both the origin of the genetic code and mRNA-protein interactions, is unexplored. We compare pyrimidine content of naturally occurring mRNA coding sequences with the propensity of cognate protein sequences to interact with pyrimidines. The latter is captured by polar requirement, a measure of solubility of amino acids in aqueous solutions of pyridines, heterocycles closely related to pyrimidines. We find that the higher the pyrimidine content of an mRNA, the stronger the average propensity of its cognate protein's amino acids to interact with pyridines. Moreover, window-averaged pyrimidine profiles of individual mRNAs strongly mirror polar-requirement profiles of cognate protein sequences. For example, 4953 human proteins exhibit a correlation between the two with |R| > 0.8. In other words, pyrimidine-rich mRNA regions quantitatively correspond to regions in cognate proteins containing residues soluble in pyrimidine mimetics and vice versa. Finally, by studying randomized genetic code variants we show that the universal genetic code is highly optimized to preserve these correlations. Overall, our findings redefine the stereo-chemical hypothesis concerning code's origin and provide evidence of direct complementary interactions between mRNAs and cognate proteins before development of ribosomal decoding, but also presently, especially if both are unstructured.

Reimbursement in the Context of Precision Oncology Approaches in Metastatic Breast Cancer: Challenges and Experiences.

Background: Precision oncology programs using next-generation sequencing to detect predictive biomarkers are extending therapeutic options for patients with metastatic breast cancer (mBC). Regularly, based on the recommendations of the interdisciplinary molecular tumor board (iMTB), an inclusion in a clinical trial is not possible. In this case, the German health insurance system allows for the application of reimbursement for an off-label drug use. Here, we describe the current challenges and our experience with reimbursement of molecular therapies in mBC. Methods: A total of 100 applications for reimbursement of off-label therapies recommended by an iMTB were filed for patients with mBC, of which 89 were evaluable for this analysis. The approval rate was correlated with the molecular level of evidence of the respective therapy according to the National Center for Tumor Diseases (NCT) and European Society for Medical Oncology Scale for Clinical Actionability of molecular Targets (ESCAT) classification as well as with pretreatment therapy lines. Findings: Overall, 53.9% (48/89) of reimbursement applications were approved. Applications for therapies based on level of evidence m1 (NCT classification), tier I and II (ESCAT classification) had a significantly and clinically relevant increased chance of reimbursement, while a greater number of previous treatment lines had no significantly increased chance of approval, though a trend of approval toward higher treatment lines was detectable. Interpretation: Currently, the German jurisdiction seems to aggravate the clinical implementation of clinically urgently needed molecular therapies.

Proteome-wide analysis reveals clues of complementary interactions between mRNAs and their cognate proteins as the physicochemical foundation of the genetic code.

Despite more than 50 years of effort, the origin of the genetic code remains enigmatic. Among different theories, the stereochemical hypothesis suggests that the code evolved as a consequence of direct interactions between amino acids and appropriate bases. If indeed true, such physicochemical foundation of the mRNA/protein relationship could also potentially lead to novel principles of protein-mRNA interactions in general. Inspired by this promise, we have recently explored the connection between the physicochemical properties of mRNAs and their cognate proteins at the proteome level. Using experimentally and computationally derived measures of solubility of amino acids in aqueous solutions of pyrimidine analogs together with knowledge-based interaction preferences of amino acids for different nucleobases, we have revealed a statistically significant matching between the composition of mRNA coding sequences and the base-binding preferences of their cognate protein sequences. Our findings provide strong support for the stereochemical hypothesis of genetic code's origin and suggest the possibility of direct complementary interactions between mRNAs and cognate proteins even in present-day cells.

Anti-inflammatory mechanism of action of azithromycin in LPS-stimulated J774A.1 cells.

Azithromycin is a macrolide antibiotic with well-described anti-inflammatory properties which can be attributed, at least partially, to its action on macrophages. We have previously shown, with 18 different macrolide molecules, that IL-6 and PGE2 inhibition correlates with macrolide accumulation, as well as with their binding to phospholipids in J774A.1 cells. The present study was performed in order to substantiate the hypothesis that biological membranes are a target for macrolide anti-inflammatory activity. By analyzing the effect of azithromycin on overall eicosanoid production, we found that in LPS-stimulated J774A.1 cells, azithromycin, like indomethacin, inhibited the synthesis of all eicosanoids produced downstream of COX. Upstream of COX, azithromycin inhibited arachidonic acid release in the same way as a cPLA2 inhibitor, while indomethacin had no effect. Further comparison revealed that in LPS-stimulated J774A.1 cells, the cPLA2 inhibitor showed the same profile of inhibition as azithromycin in inhibiting PGE2, IL-6, IL-12p40 and arachidonic acid release. Therefore, we propose that the anti-inflammatory activity of azithromycin in this model may be due to interactions with cPLA2, causing inadequate translocation of the enzyme or disturbing physical interactions with its substrates.

Association of mutation signature effectuating processes with mutation hotspots in driver genes and non-coding regions.

Cancer driving mutations are difficult to identify especially in the non-coding part of the genome. Here, we present sigDriver, an algorithm dedicated to call driver mutations. Using 3813 whole-genome sequenced tumors from International Cancer Genome Consortium, The Cancer Genome Atlas Program, and a childhood pan-cancer cohort, we employ mutational signatures based on single-base substitution in the context of tri- and penta-nucleotide motifs for hotspot discovery. Knowledge-based annotations on mutational hotspots reveal enrichment in coding regions and regulatory elements for 6 mutational signatures, including APOBEC and somatic hypermutation signatures. APOBEC activity is associated with 32 hotspots of which 11 are known and 11 are putative regulatory drivers. Somatic single nucleotide variants clusters detected at hypermutation-associated hotspots are distinct from translocation or gene amplifications. Patients carrying APOBEC induced PIK3CA driver mutations show lower occurrence of signature SBS39. In summary, sigDriver uncovers mutational processes associated with known and putative tumor drivers and hotspots particularly in the non-coding regions of the genome.

Intensity of macrolide anti-inflammatory activity in J774A.1 cells positively correlates with cellular accumulation and phospholipidosis.

Some macrolide antibiotics were reported to inhibit interleukin-6 (IL6) and prostaglandin-E2 (PGE(2)) production by bacterial lipopolysaccharide (LPS) stimulated J774A.1 cells. Macrolides are also known to accumulate in cells and some were proven inducers of phospholipidosis. In the present study, with a set of 18 mainly 14- and 15-membered macrolides, we have investigated whether these macrolide induced phenomena in J774A.1 cells are connected. In LPS-stimulated J774A.1 cells, the extent of inhibition of proinflammatory markers (IL6 and PGE(2)) by macrolides significantly correlated with their extent of accumulation in cells, as well as with the induction of phospholipidosis, and cytotoxic effects in prolonged culture (with correlation coefficients (R) ranging from 0.78 to 0.93). The effects observed were related to macrolide binding to phospholipids (CHI IAM), number of positively charged centres, and were inversely proportional to the number of hydrogen bond donors. Similar interdependence of effects was obtained with chloroquine and amiodarone, whereas for dexamethasone and indomethacin these effects were not linked. The observed macrolide induced phenomena in J774A.1 cells were reversible and elimination of the macrolides from the culture media prevented phospholipidosis and the development of cytotoxicity in long-term cultures. Based on comparison with known clinical data, we conclude that LPS-stimulated J774A.1 cells in presented experimental setup are not a representative cellular model for the evaluation of macrolide anti-inflammatory potential in clinical trials. Nevertheless, our study shows that, at least in in vitro models, binding to biological membranes may be the crucial factor of macrolide mechanism of action.

CATCH: A Prospective Precision Oncology Trial in Metastatic Breast Cancer.

PURPOSE: CATCH (Comprehensive Assessment of clinical feaTures and biomarkers to identify patients with advanced or metastatic breast Cancer for marker driven trials in Humans) is a prospective precision oncology program that uses genomics and transcriptomics to guide therapeutic decisions in the clinical management of metastatic breast cancer. Herein, we report our single-center experience and results on the basis of the first 200 enrolled patients of an ongoing trial. METHODS: From June 2017 to March 2019, 200 patients who had either primary metastatic or progressive disease, with any number of previous treatment lines and at least one metastatic site accessible to biopsy, were enrolled. DNA and RNA from tumor tissue and corresponding blood-derived nontumor DNA were profiled using whole-genome and transcriptome sequencing. Identified actionable alterations were brought into clinical context in a multidisciplinary molecular tumor board (MTB) with the aim of prioritizing personalized treatment recommendations. RESULTS: Among the first 200 enrolled patients, 128 (64%) were discussed in the MTB, of which 64 (50%) were subsequently treated according to MTB recommendation. Of 53 evaluable patients, 21 (40%) achieved either stable disease (n = 13, 25%) or partial response (n = 8, 15%). Furthermore, 16 (30%) of those patients showed improvement in progression-free survival of at least 30% while on MTB-recommended treatment compared with the progression-free survival of the previous treatment line. CONCLUSION: The initial phase of this study demonstrates that precision oncology on the basis of whole-genome and RNA sequencing is feasible when applied in the clinical management of patients with metastatic breast cancer and provides clinical benefit to a substantial proportion of patients.

Chromothripsis in Human Breast Cancer.

Chromothripsis is a form of genome instability by which a presumably single catastrophic event generates extensive genomic rearrangements of one or a few chromosomes. Widely assumed to be an early event in tumor development, this phenomenon plays a prominent role in tumor onset. In this study, an analysis of chromothripsis in 252 human breast cancers from two patient cohorts (149 metastatic breast cancers, 63 untreated primary tumors, 29 local relapses, and 11 longitudinal pairs) using whole-genome and whole-exome sequencing reveals that chromothripsis affects a substantial proportion of human breast cancers, with a prevalence over 60% in a cohort of metastatic cases and 25% in a cohort comprising predominantly luminal breast cancers. In the vast majority of cases, multiple chromosomes per tumor were affected, with most chromothriptic events on chromosomes 11 and 17 including, among other significantly altered drivers, CCND1, ERBB2, CDK12, and BRCA1. Importantly, chromothripsis generated recurrent fusions that drove tumor development. Chromothripsis-related rearrangements were linked with univocal mutational signatures, with clusters of point mutations due to kataegis in close proximity to the genomic breakpoints and with the activation of specific signaling pathways. Analyzing the temporal order of events in tumors with and without chromothripsis as well as longitudinal analysis of chromothriptic patterns in tumor pairs offered important insights into the role of chromothriptic chromosomes in tumor evolution. SIGNIFICANCE: These findings identify chromothripsis as a major driving event in human breast cancer.

The landscape of chromothripsis across adult cancer types.

Chromothripsis is a recently identified mutational phenomenon, by which a presumably single catastrophic event generates extensive genomic rearrangements of one or a few chromosome(s). Considered as an early event in tumour development, this form of genome instability plays a prominent role in tumour onset. Chromothripsis prevalence might have been underestimated when using low-resolution methods, and pan-cancer studies based on sequencing are rare. Here we analyse chromothripsis in 28 tumour types covering all major adult cancers (634 tumours, 316 whole-genome and 318 whole-exome sequences). We show that chromothripsis affects a substantial proportion of human cancers, with a prevalence of 49% across all cases. Chromothripsis generates entity-specific genomic alterations driving tumour development, including clinically relevant druggable fusions. Chromothripsis is linked with specific telomere patterns and univocal mutational signatures in distinct tumour entities. Longitudinal analysis of chromothriptic patterns in 24 matched tumour pairs reveals insights in the clonal evolution of tumours with chromothripsis.

Mismatch Repair Deficiency Drives Durable Complete Remission by Targeting Programmed Death Receptor 1 in a Metastatic Luminal Breast Cancer Patient.

BACKGROUND: In the field of breast cancer tumor biology, triple-negative breast cancer patients are the main focus of current clinical trials exploring the use of immune checkpoint inhibitors due to higher frequencies of somatic mutations, neoantigens, and resulting tumor-specific T-cell reactivity. CASE REPORT: Here, we present the case of a 66-year-old woman with metastatic luminal breast cancer that rapidly responded to monotherapy with pembrolizumab, a monoclonal anti-PD-1 antibody. This patient obtained a partial clinical response within the first cycle of treatment and an ongoing durable complete remission after 12 weeks. Except for a transient immune-related thyreoiditis, there were no side effects observed offering remarkable quality of life to the patient. To evaluate the underlying mechanisms, we performed immunohistochemistry, explored the mutational landscape by whole-exome sequencing, and identified potential T-cell epitopes by prediction of neoantigens with high affinity binding to one of the patient's HLA. Briefly, we found a strong infiltration of CD8+ T cells without staining for PD-L1 in the tumor stroma. Exome sequencing revealed an enormous frequency of somatic and tumor-specific alterations, mainly C>T/G>A transitions. The mutational pattern was further linked to genome instability and deficient mismatch repair supported by the loss of MSH6 protein expression and therefore leading to susceptibility to immune checkpoint blockade. CONCLUSION: Within the overall goal to establish operating procedures for breast cancer immunotherapy, we propose to re-evaluate testing for deficient mismatch repair and to further intensify the search for biomarkers predictive for the success of immune checkpoint modulation including all tumor biologic subtypes of breast cancer.

A novel cloning strategy for one-step assembly of multiplex CRISPR vectors.

One key advantage of the CRISPR/Cas9 system in comparison with other gene editing approaches lies in its potential for multiplexing. Here, we describe an elaborate procedure that allows the assembly of multiple gRNA expression cassettes into a vector of choice within a single step, termed ASAP(Adaptable System for Assembly of multiplexed Plasmids)-cloning. We demonstrate the utility of ASAP-cloning for multiple CRISPR-mediated applications, including efficient multiplex gene editing, robust transcription activation and convenient analysis of Cas9 activity in the presence of multiple gRNAs.

Defective DNA damage repair leads to frequent catastrophic genomic events in murine and human tumors.

Chromothripsis and chromoanasynthesis are catastrophic events leading to clustered genomic rearrangements. Whole-genome sequencing revealed frequent complex genomic rearrangements (n = 16/26) in brain tumors developing in mice deficient for factors involved in homologous-recombination-repair or non-homologous-end-joining. Catastrophic events were tightly linked to Myc/Mycn amplification, with increased DNA damage and inefficient apoptotic response already observable at early postnatal stages. Inhibition of repair processes and comparison of the mouse tumors with human medulloblastomas (n = 68) and glioblastomas (n = 32) identified chromothripsis as associated with MYC/MYCN gains and with DNA repair deficiencies, pointing towards therapeutic opportunities to target DNA repair defects in tumors with complex genomic rearrangements.

Integrative genomic and transcriptomic analysis of leiomyosarcoma.

Leiomyosarcoma (LMS) is an aggressive mesenchymal malignancy with few therapeutic options. The mechanisms underlying LMS development, including clinically actionable genetic vulnerabilities, are largely unknown. Here we show, using whole-exome and transcriptome sequencing, that LMS tumors are characterized by substantial mutational heterogeneity, near-universal inactivation of TP53 and RB1, widespread DNA copy number alterations including chromothripsis, and frequent whole-genome duplication. Furthermore, we detect alternative telomere lengthening in 78% of cases and identify recurrent alterations in telomere maintenance genes such as ATRX, RBL2, and SP100, providing insight into the genetic basis of this mechanism. Finally, most tumors display hallmarks of "BRCAness", including alterations in homologous recombination DNA repair genes, multiple structural rearrangements, and enrichment of specific mutational signatures, and cultured LMS cells are sensitive towards olaparib and cisplatin. This comprehensive study of LMS genomics has uncovered key biological features that may inform future experimental research and enable the design of novel therapies.

Analogue encoding of physicochemical properties of proteins in their cognate messenger RNAs.

Being related by the genetic code, mRNAs and their cognate proteins exhibit mutually interdependent compositions, which implies the possibility of a direct connection between their general physicochemical properties. Here we probe the general potential of the cell to encode information about proteins in the average characteristics of their cognate mRNAs and decode it in a ribosome-independent manner. We show that average protein hydrophobicity, calculated from either sequences or 3D structures, can be encoded in an analogue fashion by many different average mRNA sequence properties with the only constraint being that pyrimidine and purine bases be clearly distinguishable on average. Moreover, average characteristics of mRNA sequences enable discrimination between cytosolic and membrane proteins even in the absence of topogenic signal-based mechanisms. Our results suggest that protein and mRNA localization may be partly determined by basic physicochemical rationales and interdependencies between the two biomolecules.

On the Contribution of Linear Correlations to Quasi-harmonic Conformational Entropy in Proteins.

We study the contribution of linear, pairwise atom-positional correlations (covariances) to absolute and relative conformational entropy as calculated by quasi-harmonic analysis of molecular dynamics (MD) trajectories (SQH and ΔSQH). By analyzing a total of 25 µs of MD simulations of ubiquitin and six of its binding partners in bound and unbound states, and 2.4 µs of simulations of eight different proteins in phosphorylated and unphosphorylated states, we show that ΔSQH represents a remarkably constant fraction of a quasi-harmonic entropy change obtained if one ignores the contribution of covariance terms and uses mass-weighted atom-positional variances only (ΔSVAR). In other words, the relative contribution of linear correlations to conformational entropy change for different proteins and in different biomolecular processes appears to be largely constant. Based on this, we establish an empirical relationship between relative quasi-harmonic conformational entropy and changes in crystallographic B-factors induced by different processes, and we use it to estimate conformational-entropic contribution to the free energy of binding for a large set of protein complexes based on their X-ray structures. Our results suggest a simple way for relating other types of dynamical observables with conformational entropy in the absence of information on correlated motions, such as in the case of NMR order parameters.

Characterization of rhodamine-123, calcein and 5(6)-carboxy-2',7'-dichlorofluorescein (CDCF) export via MRP2 (ABCC2) in MES-SA and A549 cells.

Based on our initial results on the effects of several ATP-binding cassette (ABC) transporter inhibitors on rhodamine-123 efflux from A549, a human lung carcinoma, and MES-SA, a human uterine sarcoma cell line, the aim of this study was to identify the transporter responsible for this export. Export of two fluorescent dyes, rhodamine-123 and calcein, was investigated in both cell lines by testing five commonly used inhibitors of ABC transporters: verapamil, cyclosporin A, MK571, GF129018 and fumitremorgin C. A very high degree of correlation (R(2)=0.91-0.99) between results obtained in the two cell lines suggested that the same transporter was involved in the export of tested fluorescent substrates in both cell lines. Expression analysis and gene silencing techniques, as well as transport of additional substrate 5(6)-carboxy-2',7'-dichlorofluorescein (CDCF) on membrane vesicles revealed that the transporter was multidrug resistance related protein 2 (MRP2, ABCC2). Furthermore, it was found that the tested modulators showed very diverse effects on the export of three fluorescent substrates via MRP2, with some modulators being inhibitory in one, while having no effect or even stimulating the transport in the other fluorescent dye assay. Verapamil inhibited rhodamine-123, but stimulated CDCF transport and did not affect calcein export. GF129018 did not affect calcein and CDCF transport, but it inhibited rhodamine-123 transport. These results demonstrate the importance of studying various combinations of potential substrates and modulators of MRP2 in order to estimate possible drug-drug interactions in living organisms. In addition, A549 and MES-SA cells were shown to be good cell models for studying interactions of compounds with human MRP2.