Uncovering receptor-ligand interactions using a high-avidity CRISPR activation screening platform.

The majority of clinically approved drugs target proteins that are secreted or cell surface bound. However, further advances in this area have been hindered by the challenging nature of receptor deorphanization, as there are still many secreted and cell-bound proteins with unknown binding partners. Here, we developed an advanced screening platform that combines CRISPR-CAS9 guide-mediated gene activation (CRISPRa) and high-avidity bead-based selection. The CRISPRa platform incorporates serial enrichment and flow cytometry-based monitoring, resulting in substantially improved screening sensitivity for well-known yet weak interactions of the checkpoint inhibitor family. Our approach has successfully revealed that siglec-4 exerts regulatory control over T cell activation through a low affinity trans-interaction with the costimulatory receptor 4-1BB. Our highly efficient screening platform holds great promise for identifying extracellular interactions of uncharacterized receptor-ligand partners, which is essential to develop next-generation therapeutics, including additional immune checkpoint inhibitors.

Engineering CD276/B7-H3-targeted antibody-drug conjugates with enhanced cancer-eradicating capability.

CD276/B7-H3 represents a promising target for cancer therapy based on widespread overexpression in both cancer cells and tumor-associated stroma. In previous preclinical studies, CD276 antibody-drug conjugates (ADCs) exploiting a talirine-type pyrrolobenzodiazepine (PBD) payload showed potent activity against various solid tumors but with a narrow therapeutic index and dosing regimen higher than that tolerated in clinical trials using other antibody-talirine conjugates. Here, we describe the development of a modified talirine PBD-based fully human CD276 ADC, called m276-SL-PBD, that is cross-species (human/mouse) reactive and can eradicate large 500-1,000-mm3 triple-negative breast cancer xenografts at doses 10- to 40-fold lower than the maximum tolerated dose. By combining CD276 targeting with judicious genetic and chemical ADC engineering, improved ADC purification, and payload sensitivity screening, these studies demonstrate that the therapeutic index of ADCs can be substantially increased, providing an advanced ADC development platform for potent and selective targeting of multiple solid tumor types.

Polyethyleneimine/polyethylene glycol-conjugated gold nanoparticles as nanoscale positive/negative controls in nanotoxicology: testing in frog embryo teratogenesis assay-Xenopus and mammalian tissue culture system.

Despite the great potential of using positively charged gold nanoparticles (AuNPs) in nanomedicine, no systematic studies have been reported on their synthesis optimization or colloidal stability under physiological conditions until a group at the National Institute of Standards and Technology recently succeeded in producing remarkably stable polyethyleneimine (PEI)-coated AuNPs (Au-PEI). This improved version of Au-PEI (Au-PEI25kB) has increased the demand for toxicity and teratogenicity information for applications in nanomedicine and nanotoxicology. In vitro assays for Au-PEI25kB in various cell lines showed substantial active cytotoxicity. For advanced toxicity research, the frog embryo teratogenesis assay-Xenopus (FETAX) method was employed in this study. We observed that positively-charged Au-PEI25kB exhibited significant toxicity and teratogenicity, whereas polyethylene glycol conjugated AuNPs (Au-PEG) used as comparable negative controls did not. There is a characteristic avidity of Au-PEI25kB for the jelly coat, the chorionic envelope (also known as vitelline membrane) and the cytoplasmic membrane, as well as a barrier effect of the chorionic envelope observed with Au-PEG. To circumvent these characteristics, an injection-mediated FETAX approach was utilized. Like treatment with the FETAX method, the injection of Au-PEI25kB severely impaired embryo development. Notably, the survival/concentration curve that was steep when the standard FETAX approach was employed became gradual in the injection-mediated FETAX. These results suggest that Au-PEI25kB may be a good candidate as a nanoscale positive control material for nanoparticle analysis in toxicology and teratology.

Urine 5-Eicosatetraenoic Acids as Diagnostic Markers for Obstructive Sleep Apnea.

Early detection of obstructive sleep apnea (OSA) is needed to reduce cardiovascular sequelae and mortality. Full-night polysomnography has been used for diagnosing OSA, but it is too expensive and inconvenient for patients to handle. Metabolome-wide analyses were performed to find and validate surrogate markers for OSA. We further investigated the mechanism underlying hypoxic induction of the markers in human cells and mice. Arachidonic acid derivatives 5-HETE and 5-oxoETE were detected in urine samples. The levels (mean ± SD, ng per mg creatinine) of 5-HETE and 5-oxoETE were 56.4 ± 26.2 and 46.9 ± 18.4 in OSA patients, respectively, which were significantly higher than those in controls (22.5 ± 4.6 and 18.7 ± 3.6). Both levels correlated with the apnea-hypopnea index and the lowest oxygen saturation on polysomnography. After the treatment with the continuous positive airway pressure, the metabolite levels were significantly reduced compared with those before the treatment. In human mononuclear cells subjected to intermittent hypoxia, 5-HETE and 5-oxoETE productions were induced by hypoxia-inducible factor 1 and glutathione peroxidase. When mice were exposed to intermittent hypoxia, 5-HETE and 5-oxoETE were excreted more in urine. They were identified and verified as new OSA markers reflecting hypoxic stress. The OSA markers could be used for OSA diagnosis and therapeutic evaluation.

Cervical cancer is addicted to SIRT1 disarming the AIM2 antiviral defense.

Mammalian cells are equipped with antiviral innate immunity. To survive and grow, human papilloma virus (HPV)-infected cervical cancer cells must overcome this host defense system. However, the precise mechanism whereby cervical cancer cells evade the immunity is not fully understood. We noted that Sirtuin 1 (SIRT1) is overexpressed in HPV-infected cervical cancer cells and hypothesized that SIRT1 counteracts antiviral immunity. Here, we found that cervical cancer cells undergo massive death by SIRT1 knockdown, but this effect is reversed by SIRT1 restoration. SIRT1-knocked-down cells showed representative features of pyroptosis, as well as highly expressed absent in melanoma 2 (AIM2) and its downstream genes related to the inflammasome response. Mechanistically, SIRT1 repressed the NF-κB-driven transcription of the AIM2 gene by destabilizing the RELB mRNA. Interestingly, pyroptotic death signaling in SIRT1-knocked-down cells was transmitted to naïve cervical cancer cells, which was mediated by extracellular vesicles carrying AIM2 inflammasome proteins. Furthermore, the growth of cervical cancer xenografts was significantly inhibited by either SIRT1-targeting siRNAs or SIRT1-knockdown-derived extracellular vesicles. Immunohistochemical analyses showed that SIRT1 expression correlated with poor clinical outcomes in cervical cancer. In conclusion, SIRT1 enabled HPV-infected cervical cancer cells to continue growing by nullifying AIM2 inflammasome-mediated immunity. Without SIRT1, cervical cancer cells could no longer survive because of the derepression of the AIM2 inflammasome. SIRT1 could therefore be a target for the effective treatment of cervical cancer.

Accelerated tumor growth under intermittent hypoxia is associated with hypoxia-inducible factor-1-dependent adaptive responses to hypoxia.

Mounting evidence has revealed a causative role of intermittent hypoxia (IH) in cancer progression in mouse models of obstructive sleep apnea (OSA), but most studies have focused on the effects of IH following tumor implantation using an exposure to single IH frequency. Thus, we aimed to investigate 1) the potential effect of IH on the initial tumor growth in patients with OSA without an interaction with other mechanisms induced by IH in mice and 2) the influence of the IH frequency on tumor growth, which were tested using pre-conditioning with IH (Pre-IH) and 2 different IH frequencies, respectively. Pre-IH was achieved by alternatively maintaining melanoma cells between normoxia (10 min, 21% O2) and hypoxia (50 min, 1% O2) for 7 days (12 cycles per day) before administering them to mice. The conditions for IH-1 and IH-2 were 90 s of 12% FiO2 followed by 270s of 21% FiO2 (10 cycles/h), and 90 s of 12% FiO2 and 90 s of 21% FiO2 (20 cycles/h), respectively, for 8 h per day. Tumor growth was significantly higher in the Pre-IH group than in the normoxia group. In addition, the IH-2 group showed more accelerated tumor growth compared to the normoxia and IH-1 groups. Immunohistochemistry and gene-expression results consistently showed the up-regulation of molecules associated with HIF-1α-dependent hypoxic adaptation in tumors of the Pre-IH and IH-2 groups. Our findings reveal that IH increased tumor progression in a frequency-dependent manner, regardless of whether it was introduced before or after in vivo tumor cell implantation.

Sirtuin 1 attenuates nasal polypogenesis by suppressing epithelial-to-mesenchymal transition.

BACKGROUND: Nasal polyps (NPs) imply a refractory clinical course in patients with chronic rhinosinusitis (CRS). Previously, we showed that hypoxia-inducible factor (HIF) 1 could mediate nasal polypogenesis through epithelial-to-mesenchymal transition (EMT). Sirtuin 1 (SIRT1), a histone deacetylase, reportedly suppresses the transcriptional activity of HIF-1. Thus we hypothesized that SIRT1 attenuates nasal polyposis by inhibiting HIF-1-induced EMT. OBJECTIVE: We sought to determine the role of SIRT1 in patients with nasal polyposis. METHODS: The effects of SIRT1 on nasal polypogenesis were investigated in previously developed murine models. Immunohistochemistry, immunoblotting, and immunoprecipitation were done to evaluate SIRT1, EMT, and hypoxic markers in human nasal epithelial cells or sinonasal tissues from the mice and the patients with CRS with or without NPs. RESULTS: SIRT1 transgenic mice had significantly fewer mucosal lesions with epithelial disruption and fewer NPs than wild-type (WT) mice. In addition, resveratrol (a SIRT1 activator) treatment suppressed nasal polypogenesis in WT mice; however, sirtinol (a SIRT1 inhibitor) administration increased the polyp burden in SIRT1 transgenic mice. In sinonasal specimens from patients with CRS, SIRT1 was downregulated in the mucosa from patients with polyps compared with levels seen in patients without polyps. SIRT1 overexpression or activation reversed hypoxia-induced EMT in human nasal epithelial cells. The intranasal transfection of a small hairpin SIRT1 lentiviral vector induced more nasal polypoid lesions in SIRT1 transgenic mice. Finally, mucosal extracts from patients with CRS without NPs increased SIRT1 expression in nasal epithelial cells, whereas those from patients with CRS with NPs did not. CONCLUSION: SIRT1 suppressed NP formation, possibly because of inhibition of HIF-1-induced EMT. Thus nasal epithelium SIRT1 might be a therapeutic target for NPs.

HIF-1α Upregulation due to Depletion of the Free Ubiquitin Pool.

Hypoxia-inducible factor 1alpha (HIF-1α), which transactivates a variety of hypoxia-induced genes, is rapidly degraded under nomoxia through the hydroxylation-ubiquitination-proteasome pathway. In this study, we addressed how HIF-1α is stabilized by proteasome inhibitors. The ubiquitin pool was rapidly reduced after proteasome inhibition, followed by the accumulation of non-ubiquitinated HIF-1α. The poly-ubiquitination of HIF-1α was resumed by restoration of free ubiquitin, which suggests that the HIF-1α stabilization under proteasome inhibition is attributed to depletion of the free ubiquitin pool. Ni(2+) and Zn(2+) also stabilized HIF-1α with depletion of the free ubiquitin pool and these effects of metal ions were attenuated by restoration of free ubiquitin. Ni(2+) and Zn(2+) may disturb the recycling of free ubiquitin, as MG132 does. Based on these results, the state of the ubiquitin pool seems to be another critical factor determining the cellular level of HIF-1α.

IL-25 as a novel therapeutic target in nasal polyps of patients with chronic rhinosinusitis.

BACKGROUND: Chronic rhinosinusitis (CRS) with nasal polyps (NPs) in Western populations is associated with TH2 cytokine polarization. IL-25, an IL-17 family cytokine, was recently reported to induce TH2-type immune responses and to contribute to several allergic diseases, such as atopic dermatitis and asthma. However, the role of IL-25 in Asian patients with nasal polyposis remains unclear. OBJECTIVE: We sought to determine the role of IL-25 in Asian patients with nasal polyposis and CRS. METHODS: We investigated IL-25 expression and its cellular origins in NPs of human subjects using immunohistochemistry (IHC), quantitative RT-PCR, and ELISA of NP tissues. Correlations between IL-25 expression and expression of other inflammatory markers in NP tissues were also explored. Anti-IL-25 neutralizing antibody was administered in an ovalbumin- and staphylococcal enterotoxin B-induced murine NP model to confirm the function of IL-25 during nasal polypogenesis. RESULTS: IL-25 expression was upregulated in NP mucosa from patients with CRS with NPs compared with uncinate process tissue from control subjects and those with CRS without NPs. Overexpression of epithelial IL-25 was confirmed by using IHC, and double IHC staining showed that tryptase-positive cells were one of the main sources of IL-25 among immune cells. Furthermore, IL-17 receptor B levels were also increased in immune cells of patients with NPs compared with those in control subjects. In NPs IL-25 mRNA expression positively correlated with the expression of several inflammatory markers, including T-box transcription factor, RAR-related orphan receptor C, GATA3, eosinophil cationic protein, TGF-ß1, and TGF-ß2. IL-25 was more abundant in the murine NP model compared with control mice, and similar correlations between IL-25 and inflammatory markers were observed in murine models. Anti-IL-25 treatment reduced the number of polyps, mucosal edema thickness, collagen deposition, and infiltration of inflammatory cells, such as eosinophils and neutrophils. This treatment also inhibited expression of local inflammatory cytokines, such as IL-4 and IFN-γ. Furthermore, expression of CCL11, CXCL2, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1 in the nasal mucosa was suppressed in the anti-IL-25-treated group. CONCLUSION: Our results suggest that IL-25 secreted from the sinonasal epithelia and infiltrating mast cells plays a crucial role in the pathogenesis of CRS with NPs in Asian patients. In addition, our results suggest the novel possibility of treating nasal polyposis with anti-IL-25 therapy.

ITF2 prevents activation of the ß-catenin-TCF4 complex in colon cancer cells and levels decrease with tumor progression.

BACKGROUND & AIMS: Immunoglobulin transcription factor 2 (ITF2) was believed to promote neoplastic transformation via activation of ß-catenin. However, ITF2 recently was reported to suppress colon carcinogenesis. We investigated the roles of ITF2 in colorectal cancer cell lines and tumor formation and growth in mice. METHODS: Levels of ITF2, ß-catenin, and c-Myc were measured in 12 human colorectal tumor samples and by immunohistochemistry. ITF2 regulation of ß-catenin and T-cell factor (TCF) were analyzed using luciferase reporter, reverse-transcription quantitative polymerase chain reaction, flow cytometry, and immunoblot analyses. Mice were given subcutaneous injections of human colorectal cancer cell lines that stably express ITF2, small hairpin RNAs to reduce levels of ITF2, or control plasmids; xenograft tumor growth was assessed. Human colorectal carcinoma tissue arrays were used to associate levels of ITF2 expression and clinical outcomes. RESULTS: Levels of ß-catenin, cMyc, and ITF2 were increased in areas of human colon adenomas and carcinomas, compared with nontumor areas of the same tissues. ITF2 levels were reduced and cMyc levels were increased in areas of carcinoma, compared with adenoma. In human colorectal cancer cell lines, activation of the ß-catenin-TCF4 complex and expression of its target genes were regulated negatively by ITF2. ITF2 inhibited formation of the ß-catenin-TCF4 complex by competing with TCF4 for ß-catenin binding. Stable transgenic expression of ITF2 in human colorectal cancer cell lines reduced their proliferation and tumorigenic potential in mice, whereas small hairpin RNA knockdown of ITF2 promoted growth of xenograft tumors in mice. In an analysis of colorectal tumor tissue arrays, loss of ITF2 from colorectal tumor tissues was associated with poor outcomes of patients. A gene set enrichment analysis supported the negative correlation between the level of ITF2 and activity of the ß-catenin-TCF4 complex. CONCLUSIONS: In human colorectal cancer cell lines and tissue samples, ITF2 appears to prevent activation of the ß-catenin-TCF4 complex and transcription of its gene targets. Loss of ITF2 promotes the ability of colorectal cancer cells to form xenograft tumors, and is associated with tumor progression and shorter survival times of patients.