Multi-SUMOylation of NAC1 is essential for the growth of prostate cancer cells.

Nucleus accumbens-associated 1 (NAC1) is a member of pox virus and zinc finger/bric-a-brac tramtrack broad complex (BTB/POZ) gene family. Overexpression of NAC1 is implicated in cancer development, recurrence and chemotherapy resistance. In our previous study, we found NAC1 was a potential small ubiquitin-like modifier (SUMO) substrate in prostate cancer cells. However, there was still lack of evidences to further support and validate the result. In this work, we found that NAC1 is a multi-SUMO-sites acceptor. The SUMO acceptor lysines were K167, K318, K368, K483 and K498. SUMOylation didn't alter the localization of NAC1, but facilitated the formation of NAC1 nuclear bodies. Compared with NAC1 wild type (NAC1 WT), the SUMO-sites mutant of NAC1 (NAC1 SM) suppressed cell proliferation and tumor growth in cellular and animal levels. This work uncovered the function of SUMOylation of NAC1 in prostate cancer cells.

Microfluidic Immunoassays for Sensitive and Simultaneous Detection of IgG/IgM/Antigen of SARS-CoV-2 within 15 min.

The outbreak of SARS-CoV-2 is posing serious global public health problems. Facing the emergence of this pandemic, we established a portable microfluidic immunoassay system for easy-to-use, sensitive, rapid (<15 min), multiple, and on-site detection of IgG/IgM/Antigen of SARS-CoV-2 simultaneously. This integrated method was successfully applied for detecting SARS-CoV-2 IgM and IgG antibodies in clinical human serum as well as SARS-CoV-2 antigen in pharyngeal swabs from 26 patients with COVID-19 infection and 28 uninfected people. The assay demonstrated high sensitivity and specificity, which is promising for the diagnosis and monitoring as well as control of SARS-CoV-2 worldwide.

Type VI secretion system contributes to Enterohemorrhagic Escherichia coli virulence by secreting catalase against host reactive oxygen species (ROS).

Enterohemorrhagic Escherichia coli (EHEC) is one major type of contagious and foodborne pathogens. The type VI secretion system (T6SS) has been shown to be involved in the bacterial pathogenicity and bacteria-bacteria competition. Here, we show that EHEC could secrete a novel effector KatN, a Mn-containing catalase, in a T6SS-dependent manner. Expression of katN is promoted by RpoS and OxyR and repressed by H-NS, and katN contributes to bacterial growth under oxidative stress in vitro. KatN could be secreted into host cell cytosol after EHEC is phagocytized by macrophage, which leads to decreased level of intracellular reactive oxygen species (ROS) and facilitates the intramacrophage survival of EHEC. Finally, animal model results show that the deletion mutant of T6SS was attenuated in virulence compared with the wild type strain, while the deletion mutant of katN had comparable virulence to the wild type strain. Taken together, our findings suggest that EHEC could sense oxidative stress in phagosome and decrease the host cell ROS by secreting catalase KatN to facilitate its survival in the host cells.

Important role of SUMOylation of Spliceosome factors in prostate cancer cells.

Sentrin/SUMO (small ubiquitin-like modifier)-specific proteases (SENPs) have been implicated in the development of prostate cancer. However, due to the low abundance of SUMO-modified proteins and high activity of SENPs, the SUMO substrates affected by SENPs in prostate cancer cells are largely unknown. Here, we identified SI2, a novel cell-permeable SENP-specific inhibitor, by high-throughput screening. Using SI2 as a way of inhibiting the activity of SENPs and the SUMO stably transfected PC3 cells as a prostate cancer model, in combination with the stable isotope labeling with amino acids (SILAC) quantitative proteomic technique, we identified more than 900 putative target proteins of SUMO, in which 231 proteins were further subjected to bioinformatic analysis. In the highly enriched spliceosome pathway, we validated that USP39, HSPA1A, and HSPA2 were novel target proteins of SUMO. Furthermore, we demonstrated that K6, K16, K29, K51, and K73 were the SUMOylation sites of USP39. Mutation of these SUMO modification sites of USP39 further promoted the proliferation-enhancing effect of USP39 on prostate cancer cells. This study provides the SUMOproteome of PC3 cells and reveals that SUMOylation of spliceosome factors may be implicated in the pathogenesis of prostate cancer. Optimization of SI2 for isotype-specific SENP inhibitors warrants further investigation.

A Machine learning model for predicting sepsis based on an optimized assay for microbial cell-free DNA sequencing.

OBJECTIVE: To integrate an enhanced molecular diagnostic technique to develop and validate a machine-learning model for diagnosing sepsis. METHODS: We prospectively enrolled patients suspected of sepsis from August 2021 to August 2023. Various feature selection algorithms and machine learning models were used to develop the model. The best classifier was selected using 5-fold cross validation set and then was applied to assess the performance of the model in the testing set. Additionally, we employed the Shapley Additive exPlanations (SHAP) method to illustrate the effects of the features. RESULTS: We established an optimized mNGS assay and proposed using the copies of microbe-specific cell-free DNA per milliliter of plasma (CPM) as the detection signal to evaluate the real burden, with strong precision and high accuracy. In total, 237 patients were eligible for participation, which were randomly assigned to either the training set (70 %, n = 165) or the testing set (30 %, n = 72). The random forest classifier achieved accuracy, AUC and F1 scores of 0.830, 0.918 and 0.856, respectively, outperforming other machine learning models in the training set. Our model demonstrated clinical interpretability and achieved good prediction performance in differentiating between bacterial sepsis and non-sepsis, with an AUC value of 0.85 and an average precision of 0.91 in the testing set. Based on the SHAP value, the top nine features of the model were PCT, CPM, CRP, ALB, SBPmin, RRmax, CREA, PLT and HRmax. CONCLUSION: We demonstrated the potential of machine-learning approaches for predicting bacterial sepsis based on optimized mcfDNA sequencing assay accurately.

2-(4-Chlorophenyl)-2-oxoethyl 4-benzamidobenzoate derivatives, a novel class of SENP1 inhibitors: Virtual screening, synthesis and biological evaluation.

Prostate cancer is one of the most prevalent types of malignant cancers in men and has a high mortality rate among all male cancers. Previous studies have demonstrated that Sentrin/SUMO-specific protease 1 (SENP1) plays an important role in the occurrence and development of prostate cancer, and has been identified as a novel drug target for development of small molecule drugs against prostate cancer. In this paper, we used virtual screening and docking to identify compound J5 as a novel lead compound inhibiting SENP1, from SPECS library. We further investigated the SAR (structure-activity relationship) of the benzoate substituent of compound J5, and discovered compounds 8d and 8e as better small molecule inhibitors of SENP1. Both compounds are the high potent SENP1 small molecule inhibitors discovered up to date, and further lead optimization may lead to a series of novel anti-SENP1 agents. Further SAR studies are in process and will be reported in due course.

Ikaros is degraded by proteasome-dependent mechanism in the early phase of apoptosis induction.

Ikaros is an important transcription factor involved in the development and differentiation of hematopoietic cells. In this work, we found that chemotherapeutic drugs or ultraviolet radiation (UV) treatment could reduce the expression of full-length Ikaros (IK1) protein in less than 3h in leukemic NB4, Kasumi-1 and Jurkat cells, prior to the activation of caspase-3. Etoposide treatment could not alter the mRNA level of IK1 but it could shorten the half-life of IK1. Co-treatment with the proteasome inhibitor MG132 or epoxomicin but not calpain inhibitor calpeptin inhibited etoposide-induced Ikaros downregulation. Overexpression of IK1 could accelerate etoposide-induced apoptosis in NB4 cells, as evidenced by the increase of Annexin V positive cells and the more early activation of caspase 3. To our knowledge, this is the first report to show that upon chemotherapy drugs or UV treatment, IK1 could be degraded via the proteasome system in the early phase of apoptosis induction. These data might shed new insight on the role of IK1 in apoptosis and the post-translational regulation of IK1.

Design, synthesis, and biological evaluation of benzodiazepine-based SUMO-specific protease 1 inhibitors.

As the best-characterized ubiquitin-like protein (UBL), small ubiquitin-related modifier (SUMO) was found to conjugate with a number of proteins to regulate cellular functions including transcription, signal transduction, and cell cycle. While E1, E2 and E3 ligases are responsible for the forward SUMOylation reaction, SUMO-specific proteases (SENPs) reversibly remove SUMO from the SUMOylated proteins. Recently, SENP1 was found to be a potential therapeutic target for the treatment of prostate cancers, but the design and synthesis of its inhibitors have not been reported. We designed and synthesized a series of benzodiazepine-based SENP1 inhibitors, and they showed inhibitory activity as good as IC(50)=9.2µM (compound 38). The structure-activity relationship was also discussed.

Plasma Microbial Cell-Free DNA Sequencing Technology for the Diagnosis of Sepsis in the ICU.

Sepsis is a common life-threatening disease in the intensive care unit (ICU) that is usually treated empirically without pathogen identification. As a non-invasive and high-throughput technology, plasma microbial cell-free DNA (mcfDNA) sequencing can detect unknown pathogens independent of previous clinical or laboratory information. In this study, a total of 199 cases suspected of bloodstream infection (BSI) from January 2020 to June 2020 were collected, and potential pathogens were detected by simultaneous blood culture and plasma mcfDNA sequencing. Other clinical microbiological assays were performed within 7 days of plasma mcfDNA sequencing, including smear, culture of samples taken from relevant infected sites, and ß-D-glucan/galactomannan (BDG/GM) tests, among others. The diagnoses were classified as sepsis [94 (47.2%)], non-sepsis [87 (43.7%)], and non-infectious disease [18 (9.0%)]. The sensitivity and specificity of plasma mcfDNA sequencing for diagnosing sepsis were 68.1 and 63.2%, respectively, which were significantly better than those of blood culture, especially for the common bacteria that cause hospital-acquired infection, namely, Acinetobacter baumannii (p < 0.01) and Klebsiella pneumoniae (p < 0.01), and DNA viruses (plasma mcfDNA sequencing only, p < 0.01). However, there was no significant difference in the rate of positivity between plasma mcfDNA sequencing and blood culture for antibiotic-non-exposed cases (43.6 vs. 30.9%, p = 0.17). In the non-sepsis group, 44.8% of cases (13/29) detected only by plasma mcfDNA sequencing showed infections in other parts of the body, such as lower respiratory infection (LRI), intra-abdominal infection (IAI) and central nervous system infection (CNSI). For some common pathogens (not including anaerobes), turnaround time (TAT) 3 (TAT from the initiation of blood sample processing by nucleic acid extraction to the completion of sequencing analysis) was longer than TAT1 (TAT from blood culture bottles in Virtuo to off Virtuo). With disease progression, significant dynamic changes in microbial species were clearly detected by plasma mcfDNA sequencing.

Sample-to-Answer and Routine Real-Time RT-PCR: A Comparison of Different Platforms for SARS-CoV-2 Detection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is spreading all over the world and has caused millions of deaths. Several sample-to-answer platforms, including Cepheid Xpert Xpress SARS-CoV-2 (Xpert Xpress), have received emergency use authorization for SARS-CoV-2 nucleic acid detection as a point of care test in the United States. However, their application niche is unclear when compared with real-time RT-PCR assays cleared by the National Medical Products Administration in China. In this study, the clinical performance, sensitivity, and workflow of Xpert Xpress and two real-time RT-PCR kits (BioGerm kit and Sansure kit) were evaluated by the specimens from 86 symptomatic patients. The positive percent agreement of Xpert Xpress was 100% compared with 96.15% for the BioGerm kit and 90% for the Sansure kit. The negative percent agreement was 100% for all three assays. The limit of detection is 100 copies/mL for Xpert Xpress and 500 copies/mL for the BioGerm kit and Sansure kit. By serially diluting five positive specimens, the Xpert Xpress had better detection capability. In the workflow and throughput analysis, the turnaround time was 51 minutes for Xpert Xpress, 150 minutes for the BioGerm kit, and 210 minutes for the Sansure kit. This study provides some indication for diagnosis methods selection.

Multicenter assessment of shotgun metagenomics for pathogen detection.

BACKGROUND: Shotgun metagenomics has been used clinically for diagnosing infectious diseases. However, most technical assessments have been limited to individual sets of reference standards, experimental workflows, and laboratories. METHODS: A reference panel and performance metrics were designed and used to examine the performance of shotgun metagenomics at 17 laboratories in a coordinated collaborative study. We comprehensively assessed the reliability, key performance determinants, reproducibility, and quantitative potential. FINDINGS: Assay performance varied significantly across sites and microbial classes, with a read depth of 20 millions as a generally cost-efficient assay setting. Results of mapped reads by shotgun metagenomics could indicate relative and intra-site (but not absolute or inter-site) microbial abundance. INTERPRETATION: Assay performance was significantly impacted by the microbial type, the host context, and read depth, which emphasizes the importance of these factors when designing reference reagents and benchmarking studies. Across sites, workflows and platforms, false positive reporting and considerable site/library effects were common challenges to the assay's accuracy and quantifiability. Our study also suggested that laboratory-developed shotgun metagenomics tests for pathogen detection should aim to detect microbes at 500 CFU/mL (or copies/mL) in a clinically relevant host context (10^5 human cells/mL) within a 24h turn-around time, and with an efficient read depth of 20M. FUNDING: This work was supported by National Science and Technology Major Project of China (2018ZX10102001).

Hexokinase 2 Depletion Confers Sensitization to Metformin and Inhibits Glycolysis in Lung Squamous Cell Carcinoma.

Lung squamous cell carcinomas (SCCs) are highly aggressive tumors, and there is currently no effective targeted therapy owing to the lack of specific mutation targets. Compared with lung adenocarcinoma (ADCs), lung SCCs reportedly utilized higher levels of glucose metabolism to meet the anabolic and catabolic needs required to sustain rapid tumor growth. Hexokinase 2 (HK2) is an enzyme that catalyzes the rate-limit and first committed step in glucose metabolism. Here, we investigated the expression and effect of HK2 in lung SCCs. We found a significantly higher HK2 expression in lung SCCs, but not lung ADC or normal tissues. HK2 depletion or inhibition decreased the glycolysis and tumor growth via activating AMPK signaling pathway, which downregulated mTORC1 activity. Furthermore, we found an increased oxygen respiration rate compensating for HK2 depletion. Thus, metformin treatment showed combinatorial therapeutic value, which resulted in greater induction of lung SCC apoptosis in vitro and in vivo. Our study suggests that HK2 depletion in combination with metformin might be a novel effective strategy for lung SCCs therapy.

A CRISPR-Cas12a-based specific enhancer for more sensitive detection of SARS-CoV-2 infection.

BACKGROUND: Real-time reverse transcription-PCR (rRT-PCR) has been the most effective and widely implemented diagnostic technology since the beginning of the COVID-19 pandemic. However, fuzzy rRT-PCR readouts with high Ct values are frequently encountered, resulting in uncertainty in diagnosis. METHODS: A Specific Enhancer for PCR-amplified Nucleic Acid (SENA) was developed based on the Cas12a trans-cleavage activity, which is specifically triggered by the rRT-PCR amplicons of the SARS-CoV-2 Orf1ab (O) and N fragments. SENA was first characterized to determine its sensitivity and specificity, using a systematic titration experiment with pure SARS-CoV-2 RNA standards, and was then verified in several hospitals, employing a couple of commercial rRT-PCR kits and testing various clinical specimens under different scenarios. FINDINGS: The ratio (10 min/5 min) of fluorescence change (FC) with mixed SENA reaction (mix-FCratio) was defined for quantitative analysis of target O and N genes, and the Limit of Detection (LoD) of mix-FCratio with 95% confidence interval was 1.2≤1.6≤2.1. Totally, 295 clinical specimens were analyzed, among which 21 uncertain rRT-PCR cases as well as 4 false negative and 2 false positive samples were characterized by SENA and further verified by next-generation sequencing (NGS). The cut-off values for mix-FCratio were determined as 1.145 for positive and 1.068 for negative. INTERPRETATION: SENA increases both the sensitivity and the specificity of rRT-PCR, solving the uncertainty problem in COVID-19 diagnosis and thus providing a simple and low-cost companion diagnosis for combating the pandemic. FUNDING: Detailed funding information is available at the end of the manuscript.

PU.1, a novel caspase-3 substrate, partially contributes to chemotherapeutic agents-induced apoptosis in leukemic cells.

PU.1 is one of key regulators of hematopoietic cell development, a tightly-regulated lineage-specific process. Here we provide the first evidence that PU.1 protein is cleaved into two fragments of 24 kDa and 16 kDa during apoptosis progression in leukemic cell lines and primary leukemic cells. Further experiments with specific capase-3 inhibitor Z-DEVD-fmk and the in vitro proteolytic system confirmed that PU.1 is a direct target of caspase-3. Using site-directed mutagenesis analyses, the aspartic acid residues at positions 97 and 151 of PU.1 protein were identified as capsase-3 target sites. More intriguingly, the suppression of PU.1 expression by small interfering RNAs (siRNAs) significantly inhibits DNA-damaging agents NSC606985 and etoposide-induced apoptosis in leukemic cells, together with the up-regulated expression of anti-apoptotic bcl-2 gene. These results would provide new insights for understanding the mechanism of PU.1 protein in hematopoiesis and leukemogenesis.

Gprc5a depletion enhances the risk of smoking-induced lung tumorigenesis and mortality.

AIMS: Lung cancer remains the leading cause of cancer incidence and mortality. Although cigarette smoke is regarded as a high risk factor for lung tumor initiation, the role of the lung tumor suppressor GPRC5A in smoking-induced lung cancer is unclear. MAIN METHODS: We obtained two lung cancer cohorts from the TCGA and GEO databases. Bioinformatics analysis showed differential gene expression in the cohorts. Quantitative real-time PCR, Western Blot and Gprc5a-/- mice uncovered the relationship between cigarette smoke and lung cancer in the GPRC5A deletion system in vitro and in vivo. KEY FINDINGS: Bioinformatics analysis showed that the smoking lung cancer patients with low expression of GPRC5A had poor overall survival compared to the patients with high GPRC5A expression. Further analysis revealed that cancer-related stemness pathways such as the Hippo signaling pathway were induced in smoking patients with low GPRC5A expression. Additionally, we detected enriched expression of WNT5A and DLX5 in normal human lung epithelial 16HBE cells and human lung cancer H1299 cells in vitro. A relationship between cigarette smoke extract (NNK) and lung tumor initiation was observed in Gprc5a-/- mice. SIGNIFICANCE: The lung tumor suppressor gene GPRC5A played a protective role in cigarette smoke-induced lung tumor initiation, providing a target for the prevention of lung cancer development and monitoring of prognosis.

Streptococcus agalactiae Inhibits Candida albicans Hyphal Development and Diminishes Host Vaginal Mucosal TH17 Response.

Streptococcus agalactiae and Candida albicans often co-colonize the female genital tract, and under certain conditions induce mucosal inflammation. The role of the interaction between the two organisms in candidal vaginitis is not known. In this study, we found that co-infection with S. agalactiae significantly attenuated the hyphal development of C. albicans, and that EFG1-Hwp1 signal pathway of C. albicans was involved in this process. In a mouse model of vulvovaginal candidiasis (VVC), the fungal burden and the levels of pro-inflammatory cytokines, IL-1ß, IL-6 and TNF-α showed a increase on co-infection with S. agalactiae, while the level of TH17 T cells and IL-17 in the cervicovaginal lavage fluid were significantly decreased. Our results indicate that S. agalactiae inhibits C. albicans hyphal development by downregulating the expression of EFG1-Hwp1. The interaction between S. agalactiae and C. albicans may attenuate host vaginal mucosal TH17 immunity and contribute to mucosal colonization by C. albicans.

The Emerging Role of Polo-Like Kinase 1 in Epithelial-Mesenchymal Transition and Tumor Metastasis.

Polo-like kinase 1 (PLK1) is a serine/threonine kinase that plays a key role in the regulation of the cell cycle. PLK1 is overexpressed in a variety of human tumors, and its expression level often correlates with increased cellular proliferation and poor prognosis in cancer patients. It has been suggested that PLK1 controls cancer development through multiple mechanisms that include canonical regulation of mitosis and cytokinesis, modulation of DNA replication, and cell survival. However, emerging evidence suggests novel and previously unanticipated roles for PLK1 during tumor development. In this review, we will summarize the recent advancements in our understanding of the oncogenic functions of PLK1, with a focus on its role in epithelial-mesenchymal transition and tumor invasion. We will further discuss the therapeutic potential of these functions.

SUMOylation Promotes Nuclear Import and Stabilization of Polo-like Kinase 1 to Support Its Mitotic Function.

As a pivotal mitotic regulator, polo-like kinase 1 (PLK1) is under highly coordinated and multi-layered regulation. However, the pathways that control PLK1's activity and function have just begun to be elucidated. PLK1 has recently been shown to be functionally modulated by post-translational modifications (PTMs), including phosphorylation and ubiquitination. Herein, we report that SUMOylation plays an essential role in regulating PLK1's mitotic function. We found that Ubc9 was recruited to PLK1 upon initial phosphorylation and activation by CDK1/cyclin B. By in vivo and in vitro SUMOylation assays, PLK1 was identified as a physiologically relevant small ubiquitin-related modifier (SUMO)-targeted protein, preferentially modified by SUMO-1. We further showed that K492 on PLK1 is essential for SUMOylation. SUMOylation causes PLK1's nuclear import and significantly increases its protein stability, both of which are critical for normal mitotic progression and genomic integrity. Our findings suggest that SUMOylation is an important regulatory mechanism governing PLK1's mitotic function.

Targeting catalase but not peroxiredoxins enhances arsenic trioxide-induced apoptosis in K562 cells.

Despite considerable efficacy of arsenic trioxide (As2O3) in acute promyelocytic leukemia (APL) treatment, other non-APL leukemias, such as chronic myeloid leukemia (CML), are less sensitive to As2O3 treatment. However, the underlying mechanism is not well understood. Here we show that relative As2O3-resistant K562 cells have significantly lower ROS levels than As2O3-sensitive NB4 cells. We compared the expression of several antioxidant enzymes in these two cell lines and found that peroxiredoxin 1/2/6 and catalase are expressed at high levels in K562 cells. We further investigated the possible role of peroxirdoxin 1/2/6 and catalase in determining the cellular sensitivity to As2O3. Interestingly, knockdown of peroxiredoxin 1/2/6 did not increase the susceptibility of K562 cells to As2O3. On the contrary, knockdown of catalase markedly enhanced As2O3-induced apoptosis. In addition, we provide evidence that overexpression of BCR/ABL cannot increase the expression of PRDX 1/2/6 and catalase. The current study reveals that the functional role of antioxidant enzymes is cellular context and treatment agents dependent; targeting catalase may represent a novel strategy to improve the efficacy of As2O3 in CML treatment.