Reversibly Reactive Affinity Selection-Mass Spectrometry Enables Identification of Covalent Peptide Binders.

Covalent peptide binders have found applications as activity-based probes and as irreversible therapeutic inhibitors. Currently, there is no rapid, label-free, and tunable affinity selection platform to enrich covalent reactive peptide binders from synthetic libraries. We address this challenge by developing a reversibly reactive affinity selection platform termed ReAct-ASMS enabled by tandem high-resolution mass spectrometry (MS/MS) to identify covalent peptide binders to native protein targets. It uses mixed disulfide-containing peptides to build reversible peptide-protein conjugates that can enrich for covalent variants, which can be sequenced by MS/MS after reduction. Using this platform, we identified covalent peptide binders against two oncoproteins, human papillomavirus 16 early protein 6 (HPV16 E6) and peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 protein (Pin1). The resulting peptide binders efficiently and selectively cross-link Cys58 of E6 at 37 °C and Cys113 of Pin1 at room temperature, respectively. ReAct-ASMS enables the identification of highly selective covalent peptide binders for diverse molecular targets, introducing an applicable platform to assist preclinical therapeutic development pipelines.

Ultrathin Boundary-Less SnO2 Films with Surface-Activated Two-Dimensional Nanograins Enable Fast and Sensitive Hydrogen Gas Sensing.

Fast and reliable semiconductor hydrogen sensors are crucially important for the large-scale utilization of hydrogen energy. One major challenge that hinders their practical application is the elevated temperature required, arising from undesirable surface passivation and grain-boundary-dominated electron transportation in the conventional nanocrystalline sensing layers. To address this long-standing issue, in the present work, we report a class of highly reactive and boundary-less ultrathin SnO2 films, which are fabricated by the topochemical transformation of 2D SnO transferred from liquid Sn-Bi droplets. The ultrathin SnO2 films are purposely made to consist of well-crystallized quasi-2D nanograins with in-plane grain sizes going beyond 30 nm, whereby the hydroxyl adsorption and grain boundary side-effects are effectively suppressed, giving rise to an activated (101)-dominating dangling-bond surface and a surface-controlled electrical transportation with an exceptional electron mobility of 209 cm2 V-1 s-1. Our work provides a new cost-effective strategy to disruptively improve the gas reception and transduction of SnO2. The proposed chemiresistive sensors exhibit fast, sensitive, and selective hydrogen sensing performance at a much-reduced working temperature of 60 °C. The remarkable sensing performance as well as the simple and scalable fabrication process of the ultrathin SnO2 films render the thus-developed sensors attractive for long awaited practical applications in hydrogen-related industries.

Diffuse Pneumonitis after Lutetium-177-PSMA-617 Treatment in a Patient with Metastatic Castration-Resistant Prostate Cancer.

We present the case of a patient with heavily pretreated metastatic castration-resistant prostate cancer (mCRPC) who received lutetium Lu-177 vipivotide tetraxetan (also known as 177Lu-PSMA-617) due to progressive disease despite chemotherapy, hormonal therapy and radiation, including palliative mediastinal and central nervous system radiation. He was subsequently hospitalised for worsening acute onset dyspnoea despite clinically responding to therapy. Interval imaging revealed progressive multifocal ground-glass opacities superimposed on a background of underlying peribronchovascular fibrosis. Further workup, including an extensive workup to identify a possible infectious aetiology, ruled out most aetiologies leaving radiation pneumonitis (RP), radiation recall pneumonitis (RRP) and drug-induced pneumonitis as possible diagnoses secondary to 177Lu -PSMA-617. The associated imaging findings of ground-glass opacities and consolidation can be like other aetiologies such as acute infection and subsequently may be treated incorrectly. In the use of theragnostics like 177Lu -PSMA-617, it is fundamental to apply the practices of radioprotection learnt from radiotherapy, as well as to consider prior radiotherapy treatments and their possible side effects when used in conjunction.

Structure of the p53 degradation complex from HPV16.

Human papillomavirus (HPV) is a significant contributor to the global cancer burden, and its carcinogenic activity is facilitated in part by the HPV early protein 6 (E6), which interacts with the E3-ligase E6AP, also known as UBE3A, to promote degradation of the tumor suppressor, p53. In this study, we present a single-particle cryoEM structure of the full-length E6AP protein in complex with HPV16 E6 (16E6) and p53, determined at a resolution of ~3.3 Å. Our structure reveals extensive protein-protein interactions between 16E6 and E6AP, explaining their picomolar binding affinity. These findings shed light on the molecular basis of the ternary complex, which has been pursued as a potential therapeutic target for HPV-driven cervical, anal, and oropharyngeal cancers over the last two decades. Understanding the structural and mechanistic underpinnings of this complex is crucial for developing effective therapies to combat HPV-induced cancers. Our findings may help to explain why previous attempts to disrupt this complex have failed to generate therapeutic modalities and suggest that current strategies should be reevaluated.

Predictive Biomarkers of Immune Checkpoint Inhibitor-Based Mono- and Combination Therapies for Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is among the most frequent and deadly human cancers worldwide. It has been shown that interaction between immune checkpoint receptors and ligands plays a crucial role in inhibition of T cell-mediated anti-tumor immune responses, thereby assisting tumor cells to evade the host immune surveillance. Therefore, several immune checkpoint inhibitors (ICIs) that selectively block immune checkpoint receptors or ligands have been developed as clinically effective and safe immunotherapeutic agents for treating HCC, including the inhibitors targeting cytotoxic T lymphocyte-associated antigen 4, programmed death 1, and programmed death ligand 1. In addition, various combinations of ICIs and other ICIs or tyrosine kinase inhibitors or vascular endothelial growth factor inhibitors have also emerged as clinically beneficial treatments for HCC. However, the overall response rates of ICI mono-therapy and combination therapy in HCC patients remain unsatisfied, highlighting the urgent need for discovering valuable predictive biomarkers to achieve personalized therapy. This review comprehensively summarizes the literature-based evidence validating a variety of biomarkers with predictive significance for treatment responses and outcomes in HCC patients receiving various ICI-based mono- and combination therapies.

HSF1 Inhibits Antitumor Immune Activity in Breast Cancer by Suppressing CCL5 to Block CD8+ T-cell Recruitment.

Heat shock factor 1 (HSF1) is a stress-responsive transcription factor that promotes cancer cell malignancy. To provide a better understanding of the biological processes regulated by HSF1, here we developed an HSF1 activity signature (HAS) and found that it was negatively associated with antitumor immune cells in breast tumors. Knockdown of HSF1 decreased breast tumor size and caused an influx of several antitumor immune cells, most notably CD8+ T cells. Depletion of CD8+ T cells rescued the reduction in growth of HSF1-deficient tumors, suggesting HSF1 prevents CD8+ T-cell influx to avoid immune-mediated tumor killing. HSF1 suppressed expression of CCL5, a chemokine for CD8+ T cells, and upregulation of CCL5 upon HSF1 loss significantly contributed to the recruitment of CD8+ T cells. These findings indicate that HSF1 suppresses antitumor immune activity by reducing CCL5 to limit CD8+ T-cell homing to breast tumors and prevent immune-mediated destruction, which has implications for the lack of success of immune modulatory therapies in breast cancer. SIGNIFICANCE: The stress-responsive transcription factor HSF1 reduces CD8+ T-cell infiltration in breast tumors to prevent immune-mediated killing, indicating that cellular stress responses affect tumor-immune interactions and that targeting HSF1 could improve immunotherapies.

Electrophile Scanning Reveals Reactivity Hotspots for the Design of Covalent Peptide Binders.

Protein-protein interactions (PPIs) are intriguing targets in drug discovery and development. Peptides are well suited to target PPIs, which typically present with large surface areas lacking distinct features and deep binding pockets. To improve binding interactions with these topologies and advance the development of PPI-focused therapeutics, potential ligands can be equipped with electrophilic groups to enable binding through covalent mechanisms of action. We report a strategy termed electrophile scanning to identify reactivity hotspots in a known peptide ligand and demonstrate its application in a model PPI. Cysteine mutants of a known ligand are used to install protein-reactive modifiers via a palladium oxidative addition complex (Pd-OAC). Reactivity hotspots are revealed by cross-linking reactions with the target protein under physiological conditions. In a model PPI with the 9-mer peptide antigen VL9 and major histocompatibility complex (MHC) class I protein HLA-E, we identify two reactivity hotspots that afford up to 87% conversion to the protein-peptide conjugate within 4 h. The reactions are specific to the target protein in vitro and dependent on the peptide sequence. Moreover, the cross-linked peptide successfully inhibits molecular recognition of HLA-E by CD94-NKG2A possibly due to structural changes enacted at the PPI interface. The results illustrate the potential application of electrophile scanning as a tool for rapid discovery and development of covalent peptide binders.

Discovery of reactive peptide inhibitors of human papillomavirus oncoprotein E6.

Human papillomavirus (HPV) infections account for nearly all cervical cancer cases, which is the fourth most common cancer in women worldwide. High-risk variants, including HPV16, drive tumorigenesis in part by promoting the degradation of the tumor suppressor p53. This degradation is mediated by the HPV early protein 6 (E6), which recruits the E3 ubiquitin ligase E6AP and redirects its activity towards ubiquitinating p53. Targeting the protein interaction interface between HPV E6 and E6AP is a promising modality to mitigate HPV-mediated degradation of p53. In this study, we designed a covalent peptide inhibitor, termed reactide, that mimics the E6AP LXXLL binding motif by selectively targeting cysteine 58 in HPV16 E6 with quantitative conversion. This reactide provides a starting point in the development of covalent peptidomimetic inhibitors for intervention against HPV-driven cancers.

Diagnosis and management of gastrointestinal SMARCA4-deficient undifferentiated tumors.

SMARCA4-deficient undifferentiated tumors are a rare clinical entity with an aggressive clinical course, poor prognosis, and no standard-of-care therapeutic approach. These have most frequently been documented in the lung and thoracic cavity. There is a growing body of evidence for the role of immunotherapy in SMARCA4-deficient lung cancer, a disease process that historically does very poorly with cytotoxic chemotherapy alone. We present three cases where the primary tumors were instead found within the gastrointestinal system: two originating from the small bowel and one from the esophagus. In all three cases, clinical response was seen with pembrolizumab therapy, with two of the three patients receiving long-term benefit. Our series suggests that anti-PD1 immunotherapy may have promising efficacy for undifferentiated carcinomas of the gastrointestinal tract with SMARCA4 deficiency.

Percutaneous Coronary Intervention in Men, Women, and Minorities With a Previous Coronary Artery Bypass Graft Surgery (from the Pooled PLATINUM Diversity and PROMUS Element Plus Registries).

There is limited data on new-generation stent outcomes in patients with previous coronary artery bypass graft (CABG) and the associated risk of gender and race/ethnicity is unclear. We investigated 1-year outcomes after platinum chromium everolimus-eluting stent implantation in a diverse population of men, women, and minorities with previous CABG pooled from the PLATINUM Diversity (NCT02240810) and PROMUS Element Plus (NCT01589978) registries. Our primary outcome was major adverse cardiac events (MACE), a composite of all-cause death, myocardial infarction (MI), and target vessel revascularization (TVR) at 1-year post percutaneous coronary intervention (PCI). Secondary end points included all-cause death, MI, TVR, target vessel failure, and stent thrombosis. A total of 4,175 patients were included in the analysis, including 1,858 women (44.5%), 1,057 minorities (25.3%), and 662 (15.9%) with previous CABG. Patients with previous CABG were older, included more men and White patients, and had more co-morbidities compared with patients without previous CABG. At 1 year, patients with previous CABG had a higher risk of MACE (12.6% vs 7.5%, hazard ratio 1.70, 95% confidence interval 1.32 to 2.19, p <0.001) and end points, including death/MI, TVR, and target vessel failure. After multivariate adjustment, no differences were observed in MACE (adjusted hazard ratio 1.11, 95% confidence interval 0.82 to 1.49, p = 0.506) or any secondary end points. No interaction was observed between previous CABG and gender or minority status. In conclusion, in a contemporary PCI population, patients with previous CABG remain at high risk for PCI because of their elevated risk profile. Previous CABG status was however not independently associated with worse outcomes after adjustment, nor was any interaction observed with gender or race/ethnicity.

Recurrent Spontaneous Coronary Artery Dissection: A Case of Triple Trouble.

SCAD (Spontaneous Coronary Artery Dissection) is a rare disorder which rarely recurs. It is increasingly diagnosed as a cause for acute coronary syndrome (ACS) with limited insight into its pathophysiology and treatment. Lack of randomized trials and consensus guidelines make this a unique and challenging disease to manage. We describe a complex case of recurrent idiopathic SCAD with prior history of NSTE-ACS (Non-ST elevation Acute Coronary Syndrome) and discuss its management based on current clinical practices.

Exclusive Recognition of CO2 from Hydrocarbons by Aluminum Formate with Hydrogen-Confined Pore Cavities.

Exclusive capture of carbon dioxide (CO2) from hydrocarbons via adsorptive separation is an important technology in the petrochemical industry, especially for acetylene (C2H2) production. However, the physicochemical similarities between CO2 and C2H2 hamper the development of CO2-preferential sorbents, and CO2 is mainly discerned via C recognition with low efficiency. Here, we report that the ultramicroporous material Al(HCOO)3, ALF, can exclusively capture CO2 from hydrocarbon mixtures, including those containing C2H2 and CH4. ALF shows a remarkable CO2 capacity of 86.2 cm3 g-1 and record-high CO2/C2H2 and CO2/CH4 uptake ratios. The inverse CO2/C2H2 separation and exclusive CO2 capture performance from hydrocarbons are validated via adsorption isotherms and dynamic breakthrough experiments. Notably, the hydrogen-confined pore cavities with appropriate dimensional size provide an ideal pore chemistry to specifically match CO2 via a hydrogen bonding mechanism, with all hydrocarbons rejected. This molecular recognition mechanism is unveiled by in situ Fourier-transform infrared spectroscopy, X-ray diffraction studies, and molecular simulations.

Noncryogenic Air Separation Using Aluminum Formate Al(HCOO)3 (ALF).

Separating oxygen from air to create oxygen-enriched gas streams is a process that is significant in both industrial and medical fields. However, the prominent technologies for creating oxygen-enriched gas streams are both energy and infrastructure intensive as they use cryogenic temperatures or materials that adsorb N2 from air. The latter method is less efficient than the methods that adsorb O2 directly. Herein, we show, via a combination of gas adsorption isotherms, gas breakthrough experiments, neutron and synchrotron X-ray powder diffraction, Raman spectroscopy, and computational studies, that the metal-organic framework, Al(HCOO)3 (ALF), which is easily prepared at low cost from commodity chemicals, exhibits substantial O2 adsorption and excellent time-dependent O2/N2 selectivity in a range of 50-125 near dry ice/solvent (≈190 K) temperatures. The effective O2 adsorption with ALF at ≈190 K and ≈0.21 bar (the partial pressure of O2 in air) is ≈1.7 mmol/g, and at ice/salt temperatures (≈250 K), it is ≈0.3 mmol/g. Though the kinetics for full adsorption of O2 near 190 K are slower than at temperatures nearer 250 K, the kinetics for initial O2 adsorption are fast, suggesting that O2 separation using ALF with rapid temperature swings at ambient pressures is a potentially viable choice for low-cost air separation applications. We also present synthetic strategies for improving the kinetics of this family of compounds, namely, via Al/Fe solid solutions. To the best of our knowledge, ALF has the highest O2/N2 sorption selectivity among MOF adsorbents without open metal sites as verified by co-adsorption experiments..

Increased plasma levels of monocyte chemoattractant protein-1 in patients with hepatitis B virus pre-S2 gene deletion mutation predict a higher risk of hepatocellular carcinoma recurrence after curative surgical resection.

BACKGROUND: Despite resection surgery as a curative therapy for hepatocellular carcinoma (HCC), the high rate of postoperative HCC recurrence remains a big challenge for patient survival. Chronic hepatitis B virus (HBV) infection is the most important risk factor for HCC. Deletion mutation in the HBV pre-S2 gene leads to expression of an essential viral oncoprotein called pre-S2 mutant and represents an independent prognostic biomarker for HCC recurrence after curative surgical resection. Additionally, cytokines are multifunctional secreted proteins and implicated in all stages of HBV-related HCC tumorigenesis. METHODS: This study aimed to identify the cytokines whose plasma levels were associated with pre-S2 gene deletion mutation and HCC recurrence and evaluate their potential to be combined with pre-S2 gene deletion mutation in predicting HCC recurrence. RESULTS: Among a panel of 27 cytokines examined, plasma levels of monocyte chemoattractant protein-1 (MCP-1) were significantly upregulated in patients with pre-S2 gene deletion mutation or HCC recurrence. MCP-1 was validated as an independent prognostic biomarker for HCC recurrence. Moreover, patients with both the presence of pre-S2 gene deletion mutation and high levels of MCP-1 displayed a higher risk of HCC recurrence than patients with either one or none of these two biomarkers. The combination of pre-S2 gene deletion mutation and MCP-1 levels exhibited a better prognostic performance for HCC recurrence than each biomarker alone. CONCLUSIONS: This study discovered that MCP-1 levels had a significance to be as a combination biomarker with pre-S2 gene deletion mutation providing an improved performance in predicting HCC recurrence after curative surgical resection.

Branched Multimeric Peptides as Affinity Reagents for the Detection of α-Klotho Protein.

α-Klotho, an aging-related protein found in the kidney, parathyroid gland, and choroid plexus, acts as an essential co-receptor with the fibroblast growth factor 23 receptor complex to regulate serum phosphate and vitamin D levels. Decreased levels of α-Klotho are a hallmark of age-associated diseases. Detecting or labeling α-Klotho in biological milieu has long been a challenge, however, hampering the understanding of its role. Here, we developed branched peptides by single-shot parallel automated fast-flow synthesis that recognize α-Klotho with improved affinity relative to their monomeric versions. These peptides were further shown to selectively label Klotho for live imaging in kidney cells. Our results demonstrate that automated flow technology enables rapid synthesis of complex peptide architectures, showing promise for future detection of α-Klotho in physiological settings.

Aluminum formate, Al(HCOO)3: An earth-abundant, scalable, and highly selective material for CO2 capture.

A combination of gas adsorption and gas breakthrough measurements show that the metal-organic framework, Al(HCOO)3 (ALF), which can be made inexpensively from commodity chemicals, exhibits excellent CO2 adsorption capacities and outstanding CO2/N2 selectivity that enable it to remove CO2 from dried CO2-containing gas streams at elevated temperatures (323 kelvin). Notably, ALF is scalable, readily pelletized, stable to SO2 and NO, and simple to regenerate. Density functional theory calculations and in situ neutron diffraction studies reveal that the preferential adsorption of CO2 is a size-selective separation that depends on the subtle difference between the kinetic diameters of CO2 and N2. The findings are supported by additional measurements, including Fourier transform infrared spectroscopy, thermogravimetric analysis, and variable temperature powder and single-crystal x-ray diffraction.

Structure of the PAPP-ABP5 complex reveals mechanism of substrate recognition.

Insulin-like growth factor (IGF) signaling is highly conserved and tightly regulated by proteases including Pregnancy-Associated Plasma Protein A (PAPP-A). PAPP-A and its paralog PAPP-A2 are metalloproteases that mediate IGF bioavailability through cleavage of IGF binding proteins (IGFBPs). Here, we present single-particle cryo-EM structures of the catalytically inactive mutant PAPP-A (E483A) in complex with a peptide from its substrate IGFBP5 (PAPP-ABP5) and also in its substrate-free form, by leveraging the power of AlphaFold to generate a high quality predicted model as a starting template. We show that PAPP-A is a flexible trans-dimer that binds IGFBP5 via a 25-amino acid anchor peptide which extends into the metalloprotease active site. This unique IGFBP5 anchor peptide that mediates the specific PAPP-A-IGFBP5 interaction is not found in other PAPP-A substrates. Additionally, we illustrate the critical role of the PAPP-A central domain as it mediates both IGFBP5 recognition and trans-dimerization. We further demonstrate that PAPP-A trans-dimer formation and distal inter-domain interactions are both required for efficient proteolysis of IGFBP4, but dispensable for IGFBP5 cleavage. Together the structural and biochemical studies reveal the mechanism of PAPP-A substrate binding and selectivity.

Patient-derived tumor organoids as a platform of precision treatment for malignant brain tumors.

Malignant brain tumors consist of malignancies originated primarily within the brain and the metastatic lesions disseminated from other organs. In spite of intensive studies, malignant brain tumors remain to be a medical challenge. Patient-derived organoid (PDO) can recapitulate the biological features of the primary tumor it was derived from and has emerged as a promising drug-screening model for precision therapy. Here we show a proof-of-concept based on early clinical study entailing the organoids derived from the surgically resected tumors of 26 patients with advanced malignant brain tumors enrolled during December 2020 to October 2021. The tumors included nine glioma patients, one malignant meningioma, one primary lymphoma patient, and 15 brain metastases. The primary tumor sites of the metastases included five from the lungs, three from the breasts, two from the ovaries, two from the colon, one from the testis, one of melanoma origin, and one of chondrosarcoma. Out of the 26 tissues, 13 (50%) organoids were successfully generated with a culture time of about 2 weeks. Among these patients, three were further pursued to have the organoids derived from their tumor tissues tested for the sensitivity to different therapeutic drugs in parallel to their clinical care. Our results showed that the therapeutic effects observed by the organoid models were consistent to the responses of these patients to their treatments. Our study suggests that PDO can recapitulate patient responses in the clinic with high potential of implementation in personalized medicine of malignant brain tumors.

Diagnosis and Management of Atypical Chronic Myeloid Leukemia with a t(2;13)(q33;q12) Translocation.

Atypical chronic myeloid leukemia (aCML) is a rare myeloproliferative disorder that shares clinical features with chronic myeloid leukemia but lacks the classic t(9;22) BCR-ABL1 translocation and features prominent dysgranulopoiesis and granulocytic dysplasia. Challenges of this diagnosis include clinical and biologic heterogeneity, the high risk of transformation to acute myeloid leukemia, and the lack of standard treatment options. Allogeneic hematopoietic stem cell transplant is likely the preferred treatment, but this can be limited by patient psychosocial support, age, concomitant medical conditions, and availability of an appropriate donor. We report the case of a 61-year-old male with no significant past medical history diagnosed with aCML with a rare t(2;13)(q33;q12). He presented with weight loss, night sweats, splenomegaly, hyperleukocytosis, a leukoerythroblastic differential with a predominant neutrophilia, anemia, and thrombocytopenia. Subsequent peripheral blood and bone marrow studies lead to the diagnosis of aCML. He was recommended to undergo an allogeneic stem cell transplant evaluation and declined. He was initially treated with hydroxyurea and imatinib to which he responded for approximately three years. After clinical progression, he was treated with sorafenib, a multiprotein kinase inhibitor more commonly used in the treatment of hepatocellular and renal cell carcinoma due to its off target FLT3 inhibition. The patient achieved complete hematologic response which has been sustained for 7 years with tolerable side effects.