bioRxiv Science⌕ Search

Biology subjects

Liu, X.-S.

Publications and source records attributed to Liu, X.-S..

13 recordsLinked to original sources

TcrDesign: De novo design of epitope specific full-length T cell receptors

T cell receptors (TCRs) are essential for adaptive immune recognition. Recently computational tools have been developed to predict the interactions between TCR and epitope, and artificial intelligence models have been proposed to generate the complementarity determining region 3 (CDR3) region of {beta} chain TCR. However, de novo design of experimentally validated, functional, full-length epitope-specific TCRs remains a significant challenge. Here we developed TcrDesign, a deep learning framework based on large-scale unlabeled TCR and epitope datasets to generate epitope-specific, full-length TCRs. TcrDesign comprises two modules: TcrDesign-B for TCR-pMHC binding prediction with state-of-the-art accuracy, and TcrDesign-G for functional full-length TCR sequence generation. Pre-trained on large-scale unlabeled datasets using transformer-based architectures, TcrDesign achieves state-of-the-art performance in both TCR-epitope binding prediction and de novo TCR sequence generation. Furthermore, epitope-major histocompatibility complex (MHC) binding and functional activation of TcrDesign-generated TCRs were experimentally validated. TcrDesign provides an efficient and modular approach for designing epitope-specific full-length TCRs, with experimental validation confirming its utility.

bioinformatics↗

Tumor hypoxia adaptation depends on FLAD1 mediated mitochondrial metabolic reprogramming

Hypoxia, a hallmark of solid tumors, promotes the malignant progression and is challenging to target. Metabolic reprogramming and the resulting metabolic vulnerabilities provide a promising strategy to target tumor hypoxia. Here we systematically compared the metabolic network differences between hypoxic and non-hypoxic cells, and developed a deep learning model, "DepFormer", to predict the dependent metabolic genes in hypoxic tumor cells. The performance of DepFormer was validated using CRISPR screening dataset. Oxidative phosphorylation was identified as the most significantly hypoxia-dependent metabolic pathway, and FLAD1 was predicted to be one of the key hypoxia-dependent metabolic genes. FLAD1 locus is amplified, and FLAD1 expression is upregulated in various tumor types, especially in hypoxic tumors. FLAD1 depletion compromises tumors adaptation to hypoxia by disrupting mitochondrial complex II activity, leading to an imbalance between succinate and fumarate, and consequent failure to adapt to hypoxia. Subsequently, we identified a drug-like inhibitor of FLAD1, which selectively inhibits the growth of tumor cells under hypoxia. Our findings reveal FLAD1 as an innovative therapeutic target for hypoxic tumors.

cancer biology↗

Single-cell copy number alteration signature analysis reveals masked patterns and potential biomarkers for cancer

Copy number alteration (CNA) is a major type of cancer genome alteration that drives cancer progression. CNA signature analysis can reveal underlying etiology and provide biomarkers for cancer treatment, and existing CNA signature analyzes are all performed using bulk tissue samples. However CNA usually affect large proportion of genome, and the CNA profile of bulk sample does not reflect the actual CNA profiles of the individual cancer cells of the sample, especially in tumors with high heterogeneity, such as hepatocellular carcinoma (HCC). Furthermore, the evolutionary trajectory of CNA mutational processes still remain elusive. Here we build a method to comprehensively analyze the CNA signatures of HCC from single-cell and bulk sample perspective, revealing patterns and potential noise signals from the usually performed bulk tissue CNA signature analysis. Single-cell signature analysis delineated the evolutionary trajectory of HCC CNA signatures, and different CNA signatures consistently emerge in different HCC evolution stages. Single-cell CNA signatures show robust performance in patient prognosis and drug sensitivity prediction. This work not only reveals specific considerations in analyzing CNA signature derived from bulk tissue but also depicts CNA evolution process and provides potential biomarkers for the prognosis and treatment of HCC patients. HighlightSingle-cell analysis reveals CNA signatures masked in bulk tissue. Single-cell analysis delineates the evolutionary trajectory of CNA signature. Small CNAs occur early and large CNAs happens late in HCC evolution. Single-cell CNA signatures show robust performance in guiding cancer clinical treatment.

genomics↗

c-Abl Kinase Targets Tight Junction Protein ZO-2 in Regulation of Cell Migration and Morphology

c-Abl is a non-receptor tyrosine kinase involved in the regulation of cell migration and morphogenesis, but underlying mechanism remains unclear. Here, we report the identification of tight junction protein ZO-2 as a bona fide substrate of c-Abl. We show that c-Abl directly binds to and phosphorylates the C-terminus of ZO-2. In addition, c-Abl stimulates the activity of JAK1, which subsequently phosphorylates the N-terminus of ZO-2. Using the RNAi-mediated knockdown/rescue strategy, we demonstrate that c-Abl regulates cellular morphology and migration through targeting ZO-2 for phosphorylation. c-Abl activity is also associated with decreased traction forces exerted on the cell substrate and reduced monolayer tension, thus corroborating c-Abl kinase activity-mediated inhibition of cell migration. Collectively, our data uncover ZO-2 as a novel mediator for c-Abl-dependent regulation of cell migration.

cell biology↗

The repertoire of copy number alteration signatures in human cancer

Copy number alterations (CNAs) are a predominant source of genetic alterations in human cancer and play an important role in cancer progression. However comprehensive understanding of the mutational processes and signatures of CNA is still lacking. Here we developed a mechanism-agnostic method to categorize CNA based on various fragment properties, which reflect the consequences of mutagenic processes and can be extracted from different types of data, including whole genome sequencing (WGS) and SNP array. The 14 signatures of CNA have been extracted from 2778 pan-cancer analysis of whole genomes (PCAWG) WGS samples, and further validated with 10851 the cancer genome atlas (TCGA) SNP array dataset. Novel patterns of CNA have been revealed through this study. The activities of some CNA signatures consistently predict cancer patients prognosis. This study provides a repertoire for understanding the signatures of CNA in cancer, with potential implications for cancer prognosis, evolution, and etiology.

bioinformatics↗

Seq2Neo: a comprehensive pipeline for cancer neoantigen im-munogenicity prediction

Neoantigens derived from somatic DNA alterations are ideal cancer-specific targets. In recent years, the combination therapy of PD-1/PD-L1 blockers and neoantigen vaccines shows clinical efficacy in original PD-1/PD-L1 blocker non-responders. However, not all somatic DNA mutations can result in immunogenicity in cancer cells, and efficient tools for predicting the immunogenicity of neoepitope are still urgently needed. Here we present the Seq2Neo pipeline, which provides a one-stop solution for neoepitope features prediction from raw sequencing data, and neoantigens derived from different types of genome DNA alterations, including point mutations, insertion deletions, and gene fusions are supported. Importantly a convolutional neural networks (CNN) based model has been trained to predict the immunogenicity of neoepitope. And this model shows improved performance compared with currently available tools in immunogenicity prediction in independent datasets. We anticipate that the Seq2Neo pipeline will become a useful tool in prediction of neoantigen immunogenicity and cancer immunotherapy. Seq2Neo is an open-source software under an academic free license (AFL) v3.0 and it is freely available at https://github.com/XSLiuLab/Seq2Neo.

bioinformatics↗

Oncogenic EFNA4 amplification promotes lung adenocarcinoma lymph node metastasis

Lymph nodes metastases are common in patients with lung cancer. And those patients are often at a higher risk for death from lung tumor than those with tumor-free lymph nodes. So-matic DNA alterations are key drivers of cancer, and copy number alterations (CNAs) are a major type of DNA alteration that promotes lung cancer progression. Here, we performed genome-wide DNA copy number analysis, and identified a novel lung cancer metastasis related gene, EFNA4. EFNA4 genome locus was significantly amplified and EFNA4 mRNA expression was significantly up-regulated in lung cancer compared with normal lung tissue, and also in lung cancer with lymph node metastases compared with lung cancer without metastasis. EFNA4 encodes Ephrin A4, which is the ligand for Eph receptors. The function of EFNA4 in human lung cancer remains largely unknown. Through cell line experiments we showed that EFNA4 overexpression contributes to lung tumor cells growth, migration and adhesion. Conversely, EFNA4 knockdown or knockout led to the growth suppression of cells and tumor xenografts in mice. Lung cancer patients with EFNA4 over-expression have poor prognosis. Together, by elucidating a new layer of the role of EFNA4 in tumor proliferation and migration, our study demonstrates a better understanding of the function of the significantly amplified and overexpressed gene EFNA4 in lung tumor metastasis and suggests EFNA4 as a potential target in metastatic lung cancer therapy. Simple SummaryLymph nodes are likely to be the first stop for lung cancer metastasis. To further investigate the mechanism of lung cancer lymph node metastasis, we performed cancer genome analysis and found that EFNA4, a member of the ephrin (EPH) family, is amplified and up-regulated in lung tumor patients, especially in patients with lymph node metastases. In vitro and in vivo experiments show that overexpression of EFNA4 promotes lung tumor cell proliferation and migration, while knockdown or knockout of EFNA4 inhibits cell proliferation and migration. Altogether, our results suggest that the DNA amplification of EFNA4 genome locus could play an oncogenic function in promoting lung cancer lymph node metastasis.

cancer biology↗

Pan-cancer quantification of neoantigen-mediated immunoediting in cancer evolution

Immunoediting, which includes three temporally distinct stages, termed elimination, equilibrium, and escape, has been proposed to explain the interactions between cancer cells and the immune system during the evolution of cancer. However the status of immunoediting in cancer remains unclear, and the existence of neoantigen depletion signal in untreated cancer has been debated. Here we developed a distribution pattern based method for quantifying neoantigen mediated negative selection in cancer evolution. Our method provides a robust and reliable quantification for immunoediting signal in an individual cancer patient. The prevalence of immunoediting signal in immunotherapy untreated cancer genome has been demonstrated with this method. Importantly, the elimination and escape stages of immunoediting can be quantified separately, tumor types with strong immunoediting-elimination tend to have weak immunoediting-escape signal, and vice versa. Quantified immunoediting-elimination signal predicts cancer immunotherapy clinical response. Immunoediting quantification provides an evolutional perspective for evaluating the antigenicity of neoantigen, and reveals a potential biomarker for cancer precision immunotherapy.

cancer biology↗

Hiplot: a comprehensive and easy-to-use web service boosting publication-ready biomedical data visualization

Modern web techniques provide an unprecedented opportunity for leveraging complex biomedical data generating in clinical, omics, and mechanism experiments. Currently, the functions for carrying out publication-ready biomedical data visualization represent primary technical hurdles in the state-of-art omics-based web services, whereas the demand for visualization-based interactive data mining is ever-growing. Here, we propose an easy-to-use web service, Hiplot (https://hiplot.com.cn), equipping with comprehensive and interactive biomedical data visualization functions (230+) including basic statistics, multi-omics, regression, clustering, dimensional reduction, meta-analysis, survival analysis, risk modeling, etc. We used the demo and real datasets to demonstrate the usage workflow and the core functions of Hiplot. It permits users to conveniently and interactively complete a few specialized visualization tasks that previously could only be done by senior bioinformatics or biostatistics researchers. A modern web client with efficient user interfaces and interaction methods has been implemented based on the custom components library and the extensible plugin system. The versatile output can also be produced in different environments via using the cross-platform portable command-line interface (CLI) program, Hctl. A switchable view between the editable data table and the file uploader/path selection could facilitate data importing, previewing, and exporting, while the plumber-based response strategy significantly reduced the time costs for generating basic scientific graphics. Diversified layouts, themes/styles, and color palettes in this website allow users to create high-quality and publication-ready graphics. Researchers devoted to both life and data science may benefit from the emerging web service.

bioinformatics↗

Extrachromosomal DNA is associated with decreased immune cell infiltration and antigen presentation, represents a potential cancer immune evasion mechanism

Extrachromosomal DNA (ecDNA) is a type of circular and tumor specific genetic element. EcDNA has been reported to display open chromatin structure, facilitate oncogene amplification and genetic material unequal segregation, and is associated with poor cancer patients prognosis. The ability of immune evasion is a typical feature for cancer progression, however the tumor intrinsic factors that determine immune evasion remain poorly understood. Here we show that the presence of ecDNA is associated with markers of tumor immune evasion, and obtaining ecDNA could be one of the mechanisms employed by tumor cells to escape immune surveillance. Tumors with ecDNA usually have comparable TMB and neoantigen load, however they have lower immune cell infiltration and lower cytotoxic T cell activity. The microenvironment of tumors with ecDNA shows increased immune desert, decreased immune enriched fibrotic types. Both MHC class I and class II antigen presentation genes expression are decreased in tumors with ecDNA, and this could be the underlying mechanism for ecDNA associated immune evasion. This study provides evidence that the presence of ecDNA is an immune escape mechanism for cancer cells.

cancer biology↗

Essential role for Ggct in erythrocyte antioxidant defense

GGCT encodes {gamma}-glutamyl cyclotransferase enzyme activity, and its expression is up-regulated in various human cancers. {gamma}-glutamyl cyclotransferase enzyme activity was originally purified from human red blood cells (RBCs), however physiological function of GGCT in RBCs is still not clear. Here we reported that Ggct deletion in mouse leads to splenomegaly and progressive anemia phenotypes, due to elevated oxidative damage and shortened life span of Ggct-/- RBCs. Ggct-/- RBCs have increased reactive oxygen species (ROS), and are more sensitive to H2O2 induced damage compared to control RBCs. Glutathione (GSH) and GSH synthesis precursor L-cysteine are decreased in Ggct-/- RBCs. Our study suggests a critical function of Ggct in RBC redox balance and life span maintenance through regulating GSH metabolism.

genetics↗

Sigflow: an automated and comprehensive pipeline for cancer genome mutational signature analysis

SummaryMutational signatures are recurring DNA alteration patterns caused by distinct mutational events during the evolution of cancer. In recent years, several bioinformatics tools are available for mutational signature analysis. However, most of them focus on specific type of mutation, or have limited scope of application. A pipeline tool for comprehensive mutational signature analysis is still lacking. Here we present Sigflow pipeline, which provides an one-stop solution for de novo signature extraction, reference signature fitting, signature stability analysis, sample clustering based on signature exposure in different types of genome DNA alterations including single base substitution (SBS), doublet base substitution (DBS), small insertion and deletion (INDEL), and copy number alteration. A Docker image is constructed to solve the complex and time-consuming installation issues, and this enables reproducible research by version control of all dependent tools along with their environments. The Sigflow pipeline can be applied to both human and mouse genomes. Availability and implementationSigflow is an open source software under academic free license (AFL) v3.0 and it is freely available at https://github.com/ShixiangWang/sigminer.workflow or https://hub.docker.com/r/shixiangwang/sigflow. Contactliuxs@shanghaitech.edu.cn

genomics↗

Revisiting neoantigen depletion signal in the untreated cancer genome

This study is arising from Van den Eynden J. et al. Nature Genetics. Lack of detectable neoantigen depletion signals in the untreated cancer genome. Van den Eynden J. et al. tried to address a very important scientific question: could the immune system eliminate cancer cells with immunogenic mutations in untreated situation? Van den Eynden J. et al. first annotated the human exome into "HLA-binding regions" and "non HLA-binding regions" based on the predicted binding affinity of nonapeptides translated from the un-mutated reference coding genome with type I HLA alleles. They hypothesized that if neoantigen depletion signal exist, the nonsynonymous mutations in "HLA-binding regions" will be negatively selected during cancer evolution, while nonsynonymous mutation in "non HLA-binding regions" will not be negatively selected. This will lead to decreased nonsynonymous vs synonymous mutation ratio (n/s) in "HLA-binding regions" compared with "non HLA-binding regions". They defined HLA-binding mutation ratio (HBMR) as the ratio of n/s in "HLA-binding regions" to "non HLA-binding regions", and reported that HBMRs are close to 1 in different types of cancer after background corrections, meaning neoantigen depletion signals are not detectable in different types of cancer. The fundamental problem of their hypothesis lies in that the actual neoantigens with immunogenicity do not overlap with their defined "HLA-binding regions". Actually, most neoantigens with immunogenicity are not located in "HLA-binding regions", when dissimilarity between mutant and wild type peptide are considered. It is the neoantigen with immunogenicity, but not nonsynonymous mutation in their defined "HLA-binding regions" undergo immunoediting based negative selection. Thus the results reported in that study are fundamentally flawed, and at this current stage we could not draw a solid conclusion as to whether the neoantigen depletion signal exists or not.

genomics↗