Unbiased interrogation of functional lysine residues in human proteome.

CRISPR screens have empowered the high-throughput dissection of gene functions; however, more explicit genetic elements, such as codons of amino acids, require thorough interrogation. Here, we establish a CRISPR strategy for unbiasedly probing functional amino acid residues at the genome scale. By coupling adenine base editors and barcoded sgRNAs, we target 215,689 out of 611,267 (35%) lysine codons, involving 85% of the total protein-coding genes. We identify 1,572 lysine codons whose mutations perturb human cell fitness, with many of them implicated in cancer. These codons are then mirrored to gene knockout screen data to provide functional insights into the role of lysine residues in cellular fitness. Mining these data, we uncover a CUL3-centric regulatory network in which lysine residues of CUL3 CRL complex proteins control cell fitness by specifying protein-protein interactions. Our study offers a general strategy for interrogating genetic elements and provides functional insights into the human proteome.

STUB1/CHIP: New insights in cancer and immunity.

The STUB1 gene (STIP1 homology and U-box-containing protein 1), located at 16q13.3, encodes the CHIP (carboxyl terminus of Hsc70-interacting protein), an essential E3 ligase involved in protein quality control. CHIP comprises three domains: an N-terminal tetratricopeptide repeat (TPR) domain, a middle coiled-coil domain, and a C-terminal U-box domain. It functions as a co-chaperone for heat shock protein (HSP) via the TPR domain and as an E3 ligase, ubiquitinating substrates through its U-box domain. Numerous studies suggest that STUB1 plays a crucial role in various physiological process, such as aging, autophagy, and bone remodeling. Moreover, emerging evidence has shown that STUB1 can degrade oncoproteins to exert tumor-suppressive functions, and it has recently emerged as a novel player in tumor immunity. This review provides a comprehensive overview of STUB1's role in cancer, including its clinical significance, impact on tumor progression, dual roles, tumor stem cell-like properties, angiogenesis, drug resistance, and DNA repair. In addition, we explore STUB1's functions in immune cell differentiation and maturation, inflammation, autoimmunity, antiviral immune response, and tumor immunity. Collectively, STUB1 represents a promising and valuable therapeutic target in cancer and immunology.

High Expression of DLGAP5 Indicates Poor Prognosis and Immunotherapy in Lung Adenocarcinoma and Promotes Proliferation through Regulation of the Cell Cycle.

Background: Lung adenocarcinoma (LUAD) is one of the most common types of cancer in the respiratory system, with a high mortality and recurrence rate. The role of disc large-associated protein 5 (DLGAP5) in LUAD progression and tumor microenvironment (TME) remains unclear. This study is aimed at revealing the functional role of DLGAP5 in LUAD based on bioinformatics analysis and experimental validation. Methods: Differential expression analysis, protein-protein interaction (PPI) network, and Cox regression analysis were applied to screen potential prognostic biomarkers. The mRNA and protein levels of DLGAP5 were analyzed using The Cancer Genome Atlas (TCGA) and the Human Protein Atlas (HPA) databases. The CCK-8 and colony formation assays were performed to assess the effect of DLGAP5 on cell proliferation. RNA sequencing (RNA-seq) and enrichment analyses were utilized to explore the biological functions of DLGAP5. Furthermore, flow cytometry was used to explore the role of DLGAP5 on the cell cycle. The ssGSEA algorithm in the R package "GSVA" was applied to quantify immune infiltrating cells, and the tumor immune dysfunction and exclusion (TIDE) algorithm was used to predict the efficacy of immunotherapy. Moreover, analyses using the cBioPortal and MethSurv databases were performed to evaluate the mutation and methylation of DLGAP5, respectively. Finally, the prognostic value of DLGAP5 was estimated using the TCGA and the Gene Expression Omnibus (GEO) databases. The nomogram model was constructed using the TCGA-LUAD cohort and evaluated by adopting calibration curves, time-dependent receiver operating characteristic (ROC) curves, and decision curve analysis (DCA). Results: DLGAP5 mRNA and protein abundance were significantly elevated in LUAD, and knockdown of DLGAP5 remarkably suppressed lung cancer cell proliferation through induction of cell cycle G1 arrest. In addition, DLGAP5 expression was positively correlated with Th2 cells and negatively correlated with B cells, T follicular helper cells, and mast cells. LUAD patients with high DLGAP5 expression may be resistant to immunotherapy. Hypermethylation levels of the cg23678254 site of DLGAP5 or its enhanced expression were unfavorable for the survival of LUAD patients. Meanwhile, DLGAP5 expression was associated with TNM stages, tumor status, and therapy outcome. Notably, the prognostic model constructed based on DLGAP5 expression exhibited great predictive capability, which was promising for clinical applications. Conclusion: DLGAP5 promotes lung cancer cell proliferation through regulation of the cell cycle and is associated with multiple immune infiltrating cells. Furthermore, DLGAP5 predicts poor prognosis and response to immunotherapy in lung adenocarcinoma.

Immune checkpoint PTPN2 predicts prognosis and immunotherapy response in human cancers.

Background: PTPN2, a member of the non-receptor protein tyrosine phosphatases family, holds a crucial role in tumorigenesis and cancer immunotherapy. However, most studies on the role of PTPN2 in cancer are limited to specific cancer types. Therefore, this study aimed to investigate the prognostic significance of PTPN2 in human cancers and its function in the tumor microenvironment. Methods: To shed light on this matter, we investigated the expression level, prognostic value, genomic alterations, molecular function, immune function, and immunotherapeutic predictive ability of PTPN2 in human cancers using the TCGA, GTEx, CGGA, GEO, cBioPortal, STRING, TISCH, TIMER2.0, ESTIMATE, and TIDE databases. Furthermore, the CCK-8 assay was utilized to detect the effect of PTPN2 on cell proliferation. Cell immunofluorescence analysis was performed to probe the cellular localization of PTPN2. Western blot was applied to examine the molecular targets downstream of PTPN2. Finally, a Nomogram model was constructed using the TCGA-LGG cohort and evaluated with calibration curves and time-dependent ROCs. Results: PTPN2 was highly expressed in most cancers and was linked to poor prognosis in ACC, GBM, LGG, KICH, and PAAD, while the opposite was true in OV, SKCM, and THYM. PTPN2 knockdown promoted the proliferation of melanoma cells, while significantly inhibiting proliferation in colon cancer and glioblastoma cells. In addition, TC-PTP, encoded by the PTPN2 gene, was primarily localized in the nucleus and cytoplasm and could negatively regulate the JAK/STAT and MEK/ERK pathways. Strikingly, PTPN2 knockdown significantly enhanced the abundance of PD-L1. PTPN2 was abundantly expressed in Mono/Macro cells and positively correlated with multiple immune infiltrating cells, especially CD8+ T cells. Notably, DLBC, LAML, OV, and TGCT patients in the PTPN2-high group responded better to immunotherapy, while the opposite was true in ESCA, KIRC, KIRP, LIHC, and THCA. Finally, the construction of a Nomogram model on LGG exhibited a high prediction accuracy. Conclusion: Immune checkpoint PTPN2 is a powerful biomarker for predicting prognosis and the efficacy of immunotherapy in cancers. Mechanistically, PTPN2 negatively regulates the JAK/STAT and MEK/ERK pathways and the abundance of PD-L1.

Research On Maize Disease Identification Methods In Complex Environments Based On Cascade Networks And Two-Stage Transfer Learning.

Achieving accurate and reliable maize disease identification in complex environments is a huge challenge. This is because disease images obtained from natural environments are often in complex contexts that may contain elements similar to disease characteristics or symptoms. Based on cascade network and two-stage transformation learning, the new method is proposed in this paper and applied the improved method to the task of identification and classification of four maize leaf types in a complex environment. The proposed method has a cascade structure which consists of a Faster R-CNN leaf detector (denoted as LS-RCNN) and a CNN disease classifier, named CENet(Complex Environment Network). The LS-RCNN detector with an attention mechanism was used to detect maize leaves from the image, and the CENet model further classified the leaf images detected in the first stage into four categories: Cercospora leaf spot, Common rust, Northern Leaf Blight, and Healthy, which allowed image features to be extracted more efficiently. The subsequent use of a two-stage transfer learning strategy to train CENet models of disease images in complex contexts allows for faster training of the models while ensuring accuracy. The experimental results show that the proposed method is used to identify four types of maize leaves with an F1-score of 99.70%, which is better than some popular CNN models and others' methods, and has a more obvious advantage in terms of training speed. The model proposed in this experiment has a positive significance for exploring other Crop variety identification and classification under complex backgrounds.

Critical roles of PTPN family members regulated by non-coding RNAs in tumorigenesis and immunotherapy.

Since tyrosine phosphorylation is reversible and dynamic in vivo, the phosphorylation state of proteins is controlled by the opposing roles of protein tyrosine kinases (PTKs) and protein tyrosine phosphatase (PTPs), both of which perform critical roles in signal transduction. Of these, intracellular non-receptor PTPs (PTPNs), which belong to the largest class I cysteine PTP family, are essential for the regulation of a variety of biological processes, including but not limited to hematopoiesis, inflammatory response, immune system, and glucose homeostasis. Additionally, a substantial amount of PTPNs have been identified to hold crucial roles in tumorigenesis, progression, metastasis, and drug resistance, and inhibitors of PTPNs have promising applications due to striking efficacy in antitumor therapy. Hence, the aim of this review is to summarize the role played by PTPNs, including PTPN1/PTP1B, PTPN2/TC-PTP, PTPN3/PTP-H1, PTPN4/PTPMEG, PTPN6/SHP-1, PTPN9/PTPMEG2, PTPN11/SHP-2, PTPN12/PTP-PEST, PTPN13/PTPL1, PTPN14/PEZ, PTPN18/PTP-HSCF, PTPN22/LYP, and PTPN23/HD-PTP, in human cancer and immunotherapy and to comprehensively describe the molecular pathways in which they are implicated. Given the specific roles of PTPNs, identifying potential regulators of PTPNs is significant for understanding the mechanisms of antitumor therapy. Consequently, this work also provides a review on the role of non-coding RNAs (ncRNAs) in regulating PTPNs in tumorigenesis and progression, which may help us to find effective therapeutic agents for tumor therapy.

A novel metabolic-immune related signature predicts prognosis and immunotherapy response in lung adenocarcinoma.

Background: Lung adenocarcinoma (LUAD) is one of the most frequent types of lung cancer, with a high mortality and recurrence rate. This study aimed to design a RiskScore to predict the prognosis and immunotherapy response of LUAD patients due to a lack of metabolic and immune-related prognostic models. Methods: To identify prognostic genes and generate a RiskScore, we conducted differential gene expression analysis, bulk survival analysis, Lasso regression analysis, and univariate and multivariate Cox regression analysis using TCGA-LUAD as a training subset. GSE31210 and GSE50081 were used as validation subsets to validate the constructed RiskScore. Following that, we explored the connection between RiskScore and clinicopathological characteristics, immune cells infiltration, and immunotherapy. In addition, we investigated into RiskScore's biological roles and constructed a Nomogram model. Results: A RiskScore was identified consisting of five genes (DKK1, CCL20, NPAS2, GNPNAT1 and MELTF). In the RiskScore-high group, LUAD patients showed decreased overall survival rates and shorter progression-free survival. Multiple clinicopathological characteristics and immune cells infiltration in TME, in particular, have been linked to RiskScore. Of note, RiskScore-related genes have been implicated to substance metabolism, carcinogenesis, and immunological pathways, among other things. Finally, the C-index of the RiskScore-based Nomogram model was 0.804 (95% CI: 0.783-0.825), and time-dependent ROC predicted probabilities of 1-, 3- and 5-year survival for LUAD patients were 0.850, 0.848 and 0.825, respectively. Conclusion: The RiskScore, which integrated metabolic and immunological features with DKK1, CCL20, NPAS2, GNPNAT1, and MELTF, could reliably predict prognosis and immunotherapy response in LUAD patients. Moreover, the RiskScore-based Nomogram model had a promising clinical application.

Identification of ERCC8 as a novel cisplatin-resistant gene in esophageal cancer based on genome-scale CRISPR/Cas9 screening.

Esophageal cancer (ESCA) is one of the most common malignant tumors of the digestive system worldwide. As a first-line drug for chemotherapy, cisplatin resistance is the major obstacle in the successful treatment of esophageal cancer. Previous studies largely failed to identify the key genes associated with cisplatin resistance. Hence, the aim of this study was to screen the cisplatin resistance-related genes of esophageal cancer using CRISPR/Cas9 gene-editing technology and Brunello iBar library. Of note, we identified ERCC8 as a novel cisplatin-resistant gene by high-throughput sequencing and cisplatin resistance assays. Based on KEGG and GO analysis, we hypothesized that the mechanism of ERCC8 involvement in cisplatin resistance is through binding to damaged DNA to perform nucleotide excision repair, contributing to the restoration of basic DNA functions and cellular life activities in ESCA. In addition, Cell proliferation and wound healing assay confirmed that ERCC8 had little effect on the proliferation and migration of esophageal cancer cells in vitro. Survival analysis showed that ERCC8 expression was not associated with OS, DSS, or FPI in patients with ESCA. Immuno-infiltration analysis indicated that increased ERCC8 expression is associated with NK cells, macrophages, T helper cells, Th1 cells, and Th2 cells. Collectively, ERCC8 may serve as a new biomarker for predicting cisplatin resistance and have the prospect of becoming an effective target for the clinical treatment of cisplatin resistance in ESCA.

SNAIL1: Linking Tumor Metastasis to Immune Evasion.

The transcription factor Snail1, a key inducer of epithelial-mesenchymal transition (EMT), plays a critical role in tumor metastasis. Its stability is strictly controlled by multiple intracellular signal transduction pathways and the ubiquitin-proteasome system (UPS). Increasing evidence indicates that methylation and acetylation of Snail1 also affects tumor metastasis. More importantly, Snail1 is involved in tumor immunosuppression by inducing chemokines and immunosuppressive cells into the tumor microenvironment (TME). In addition, some immune checkpoints potentiate Snail1 expression, such as programmed death ligand 1 (PD-L1) and T cell immunoglobulin 3 (TIM-3). This mini review highlights the pathways and molecules involved in maintenance of Snail1 level and the significance of Snail1 in tumor immune evasion. Due to the crucial role of EMT in tumor metastasis and tumor immunosuppression, comprehensive understanding of Snail1 function may contribute to the development of novel therapeutics for cancer.

Elevated IgE promotes cardiac fibrosis by suppressing miR-486a-5p.

Rationale: Cardiac fibrosis is an important feature of cardiac remodeling and is a hallmark of heart failure. Recent studies indicate that elevated IgE plays a causal role in pathological cardiac remodeling. However, the underlying mechanism of how IgE promotes cardiac fibrosis has not been fully elucidated. Methods and Results: To explore the function of IgE in cardiac fibrosis, we stimulated mouse primary cardiac fibroblasts (CFs) with IgE and found that both IgE receptor (FcεR1) and fibrosis related proteins were increased after IgE stimulation. Specific deletion of FcεR1 in CFs alleviated angiotensin II (Ang II)-induced cardiac fibrosis in mice. To investigate the mechanisms underlying the IgE-mediated cardiac fibrosis, deep miRNA-seq was performed. Bioinformatics and signaling pathway analysis revealed that IgE upregulated Col1a1 and Col3a1 expression in CFs by repressing miR-486a-5p, with Smad1 participating downstream of miR-486a-5p in this process. Lentivirus-mediated overexpression of miR-486a-5p was found to alleviate Ang II-induced myocardial interstitial fibrosis in mice. Moreover, miR-486-5p serum levels were lower in patients with heart failure than in healthy controls, and were negatively correlated with NT-proBNP levels. Conclusions: Our study demonstrates that elevated IgE promotes pathological cardiac fibrosis by modulating miR-486a-5p and downstream factors, such as Smad1. These findings suggest new targets for pathological cardiac fibrosis intervention.

OTUB1 promotes esophageal squamous cell carcinoma metastasis through modulating Snail stability.

Snail is a key regulator of epithelial-mesenchymal transition (EMT) and plays an important role in tumor progression and metastasis. Snail is rapidly degraded in the cells and its protein level is critically controlled. Although several E3 ligases regulating Snail degradation have been defined, the deubiquitinases (DUBs) responsible for Snail deubiquitination are less studied. We identified ovarian tumor domain-containing ubiquitin aldehyde binding protein 1 (OTUB1) as a DUB that stabilizes Snail through preventing its ubiquitination and proteasomal degradation. Functionally, OTUB1 facilitates metastasis of esophageal squamous cell carcinoma (ESCC) through promoting Snail protein stability. Moreover, OTUB1 is highly expressed in ESCC and higher expression of OTUB1 predicts poor prognosis. These findings suggest that OTUB1 is an essential regulator of Snail and plays a critical role in facilitating esophageal cancer progression.

Deubiquitinating enzyme PSMD14 promotes tumor metastasis through stabilizing SNAIL in human esophageal squamous cell carcinoma.

The epithelial-mesenchymal transition (EMT) transcription factor SNAIL is associated with distant metastasis and poor prognosis of esophageal squamous cell carcinoma (ESCC) patients. The proteolysis of SNAIL is mediated by the ubiquitin-proteasome system. Several E3 ligases have been characterized to promote SNAIL ubiquitination and degradation. However, the reverse process - deubiquitination of SNAIL remains largely unknown. In this study, we performed a mass spectrometry to examine the interaction between SNAIL and deubiquitinating enzyme(s). Subsequently, the deubiquitinating enzyme PSMD14 was identified to target SNAIL for deubiquitination and stabilization. Furthermore, knockdown of PSMD14 significantly blocks SNAIL-induced EMT and then suppresses tumor cell migration and invasion in vitro and tumor metastasis in vivo. In addition, the high expression level of PSMD14 predicts poor prognosis for esophageal cancer patients. These findings suggest PSMD14 as a bona fide deubiquitinating enzyme to regulate SNAIL at the post-translational level and provide a promising therapeutic strategy against tumor metastasis of esophageal cancer.

The E3 ligase HECTD3 promotes esophageal squamous cell carcinoma (ESCC) growth and cell survival through targeting and inhibiting caspase-9 activation.

Apoptosis resistance is an acquired hallmark of cancer cells and many factors can contribute to the tumor cell apoptosis resistance. In this study, we demonstrated that HECTD3, overexpressed in human esophageal squamous cell carcinoma (ESCC), confers cells resistance to cisplatin-induced apoptosis and promotes cancer cell survival. HECTD3 can bind and ubiquitinate caspase-9, which leads to inhibiting caspase-9 oligomerization and association with Apaf-1, and results in suppressing caspase-9 activation and inhibiting apoptosis. Furthermore, this antiapoptotic function of HECTD3 is dependent on its Thr-157 phosphorylation by ERK. HECTD3, but not T157A mutant, facilitates cell survival in ESCC cells in survival assay in vitro and promotes tumor growth in a xenograft mouse model in vivo. These findings establish a new mechanism of cancer cell resistance to apoptosis and provide a new potential strategy for ESCC treatment.

Brain microvascular endothelium induced-annexin A1 secretion contributes to small cell lung cancer brain metastasis.

Small cell lung cancer is the most aggressive histologic subtype of lung cancer, with a strong predilection for metastasizing to brain early. However, the cellular and molecular basis is poorly known. Here, we provided evidence to reveal the role of annexin A1 in small cell lung cancer metastasis to brain. Firstly, the elevated annexin A1 serum levels in small cell lung cancer patients were associated with brain metastasis. The levels of annexin A1 were also upregulated in NCI-H446 cells, a small cell lung cancer cell line, upon migration into the mice brain. More interestingly, annexin A1 was secreted by NCI-H446 cells in a time-dependent manner when co-culturing with human brain microvascular endothelial cells, which was identified with the detections of annexin A1 in the co-cultured cellular supernatants by ELISA and western blot. Further results showed that blockage of annexin A1 in the co-cultured cellular supernatants using a neutralized antibody significantly inhibited NCI-H446 cells adhesion to brain endothelium and its transendothelial migration. Conversely, the addition of Ac2-26, an annexin A1 mimic peptide, enhanced these effects. Furthermore, knockdown of annexin A1 in NCI-H446 cells prevented its transendothelial migration in vitro and metastasis to mice brain in vivo. Our data showed that small cell lung cancer cell in brain microvasculature microenvironment could express much more annexin A1 and release it outside, which facilitated small cell lung cancer cell to gain malignant properties of entry into brain. These findings provided a potential target for the management of SCLC brain metastasis.