Jmjd3 inhibits reprogramming by upregulating expression of INK4a/Arf and targeting PHF20 for ubiquitination.

Although somatic cell reprogramming to generate inducible pluripotent stem cells (iPSCs) is associated with profound epigenetic changes, the roles and mechanisms of epigenetic factors in this process remain poorly understood. Here, we identify Jmjd3 as a potent negative regulator of reprogramming. Jmjd3-deficient MEFs produced significantly more iPSC colonies than did wild-type cells, whereas ectopic expression of Jmjd3 markedly inhibited reprogramming. We show that the inhibitory effects of Jmjd3 are produced through both histone demethylase-dependent and -independent pathways. The latter pathway involves Jmjd3 targeting of PHF20 for ubiquitination and degradation via recruitment of an E3 ligase, Trim26. Importantly, PHF20-deficient MEFs could not be converted to fully reprogrammed iPSCs, even with knockdown of Jmjd3, Ink4a, or p21, indicating that PHF20 is required for reprogramming. Our findings demonstrate, to the best of our knowledge, a previously unrecognized role of Jmjd3 in cellular reprogramming and provide molecular insight into the mechanisms by which the Jmjd3-PHF20 axis controls this process.

Correction: Stage-Dependent and Locus-Specific Role of Histone Demethylase Jumonji D3 (JMJD3) in the Embryonic Stages of Lung Development.

[This corrects the article DOI: 10.1371/journal.pgen.1004524.].

Cross-Regulation of Two Type I Interferon Signaling Pathways in Plasmacytoid Dendritic Cells Controls Anti-malaria Immunity and Host Mortality.

Type I interferon (IFN) is critical for controlling pathogen infection; however, its regulatory mechanisms in plasmacytoid cells (pDCs) still remain unclear. Here, we have shown that nucleic acid sensors cGAS-, STING-, MDA5-, MAVS-, or transcription factor IRF3-deficient mice produced high amounts of type I IFN-α and IFN-ß (IFN-α/ß) in the serum and were resistant to lethal plasmodium yoelii YM infection. Robust IFN-α/ß production was abolished when gene encoding nucleic acid sensor TLR7, signaling adaptor MyD88, or transcription factor IRF7 was ablated or pDCs were depleted. Further, we identified SOCS1 as a key negative regulator to inhibit MyD88-dependent type I IFN signaling in pDCs. Finally, we have demonstrated that pDCs, cDCs, and macrophages were required for generating IFN-α/ß-induced subsequent protective immunity. Thus, our findings have identified a critical regulatory mechanism of type I IFN signaling in pDCs and stage-specific function of immune cells in generating potent immunity against lethal YM infection.

USP3 plays a critical role in the induction of innate immune tolerance.

Microbial products, such as lipopolysaccharide (LPS), can elicit efficient innate immune responses against invading pathogens. However, priming with LPS can induce a form of innate immune memory, termed innate immune "tolerance", which blunts subsequent NF-κB signaling. Although epigenetic and transcriptional reprogramming has been shown to play a role in innate immune memory, the involvement of post-translational regulation remains unclear. Here, we report that ubiquitin-specific protease 3 (USP3) participates in establishing "tolerance" innate immune memory through non-transcriptional feedback. Upon NF-κB signaling activation, USP3 is stabilized and exits the nucleus. The cytoplasmic USP3 specifically removes the K63-linked polyubiquitin chains on MyD88, thus negatively regulating TLR/IL1ß-induced inflammatory signaling activation. Importantly, cytoplasmic translocation is a prerequisite step for USP3 to deubiquitinate MyD88. Additionally, LPS priming could induce cytoplasmic retention and faster and stronger cytoplasmic translocation of USP3, enabling it to quickly shut down NF-κB signaling upon the second LPS challenge. This work identifies a previously unrecognized post-translational feedback loop in the MyD88-USP3 axis, which is critical for inducing normal "tolerance" innate immune memory.

NLRC5 negatively regulates the NF-kappaB and type I interferon signaling pathways.

Stringent control of the NF-kappaB and type I interferon signaling pathways is critical to effective host immune responses, yet the molecular mechanisms that negatively regulate these pathways are poorly understood. Here, we show that NLRC5, a member of the highly conserved NOD-like protein family, can inhibit the IKK complex and RIG-I/MDA5 function. NLRC5 inhibited NF-kappaB-dependent responses by interacting with IKKalpha and IKKbeta and blocking their phosphorylation. It also interacted with RIG-I and MDA5, but not with MAVS, to inhibit RLR-mediated type I interferon responses. Consistent with these observations, NLRC5-specific siRNA knockdown not only enhanced the activation of NF-kappaB and its responsive genes, TNF-alpha and IL-6, but also promoted type I interferon signaling and antiviral immunity. Our findings identify NLRC5 as a negative regulator that blocks two central components of the NF-kappaB and type I interferon signaling pathways and suggest an important role for NLRC5 in homeostatic control of innate immunity.

Assembly of the WHIP-TRIM14-PPP6C Mitochondrial Complex Promotes RIG-I-Mediated Antiviral Signaling.

Mitochondrial antiviral signaling platform protein (MAVS) acts as a central hub for RIG-I receptor proximal signal propagation. However, key components in the assembly of the MAVS mitochondrial platform that promote RIG-I mitochondrial localization and optimal activation are still largely undefined. Employing pooled RNAi and yeast two-hybrid screenings, we report that the mitochondrial adaptor protein tripartite motif (TRIM)14 provides a docking platform for the assembly of the mitochondrial signaling complex required for maximal activation of RIG-I-mediated signaling, consisting of WHIP and protein phosphatase PPP6C. Following viral infection, the ubiquitin-binding domain in WHIP bridges RIG-I with MAVS by binding to polyUb chains of RIG-I at lysine 164. The ATPase domain in WHIP contributes to stabilization of the RIG-I-dsRNA interaction. Moreover, phosphatase PPP6C is responsible for RIG-I dephosphorylation. Together, our findings define the WHIP-TRIM14-PPP6C mitochondrial signalosome required for RIG-I-mediated innate antiviral immunity.

NLRP4 negatively regulates type I interferon signaling by targeting the kinase TBK1 for degradation via the ubiquitin ligase DTX4.

Stringent control of the type I interferon signaling pathway is important for maintaining host immune responses and homeostasis, yet the molecular mechanisms responsible for its tight regulation are still poorly understood. Here we report that the pattern-recognition receptor NLRP4 regulated the activation of type I interferon mediated by double-stranded RNA or DNA by targeting the kinase TBK1 for degradation. NLRP4 recruited the E3 ubiquitin ligase DTX4 to TBK1 for Lys48 (K48)-linked polyubiquitination at Lys670, which led to degradation of TBK1. Knockdown of either DTX4 or NLRP4 abrogated K48-linked ubiquitination and degradation of TBK1 and enhanced the phosphorylation of TBK1 and the transcription factor IRF3. Our results identify a previously unrecognized role for NLRP4 in the regulation of type I interferon signaling and provide molecular insight into the mechanisms by which NLRP4-DTX4 targets TBK1 for degradation.

TRIM14 Inhibits cGAS Degradation Mediated by Selective Autophagy Receptor p62 to Promote Innate Immune Responses.

Cyclic GMP-AMP synthase (cGAS) is an essential DNA virus sensor that triggers type I interferon (IFN) signaling by producing cGAMP to initiate antiviral immunity. However, post-translational regulation of cGAS remains largely unknown. We report that K48-linked ubiquitination of cGAS is a recognition signal for p62-depdendent selective autophagic degradation. The induction of TRIM14 by type I IFN accelerates cGAS stabilization by recruiting USP14 to cleave the ubiquitin chains of cGAS at lysine (K) 414. Knockout of TRIM14 impairs herpes simplex virus type 1 (HSV-1)-triggered antiviral responses in a cGAS-dependent manner. Due to impaired type I IFN production, Trim14-/- mice are highly susceptible to lethal HSV-1 infection. Taken together, our findings reveal a positive feedback loop of cGAS signaling generated by TRIM14-USP14 and provide insights into the crosstalk between autophagy and type I IFN signaling in innate immunity.

USP38 Inhibits Type I Interferon Signaling by Editing TBK1 Ubiquitination through NLRP4 Signalosome.

TBK1 is a component of the type I interferon (IFN) signaling pathway, yet the mechanisms controlling its activity and degradation remain poorly understood. Here we report that USP38 negatively regulates type I IFN signaling by targeting the active form of TBK1 for degradation in vitro and in vivo. USP38 specifically cleaves K33-linked poly-ubiquitin chains from TBK1 at Lys670, and it allows for subsequent K48-linked ubiquitination at the same position mediated by DTX4 and TRIP. Knockdown or knockout of USP38 increases K33-linked ubiquitination, but it abrogates K48-linked ubiquitination and degradation of TBK1, thus enhancing type I IFN signaling. Our findings identify an essential role for USP38 in negatively regulating type I IFN signaling, and they provide insights into the mechanisms by which USP38 regulates TBK1 ubiquitination through the NLRP4 signalosome.

The value on SUV-derived parameters assessed on 18F-FDG PET/CT for predicting mediastinal lymph node metastasis in non-small cell lung cancer.

PURPOSE: To explore valuable predictors for mediastinal lymph node metastasis in non-small cell lung cancer (NSCLC) patients, we analyzed the potential roles of standardized uptake value (SUV)-derived parameters from preoperative 18F-FDG PET/CT combined with clinical characteristics. METHODS: Data from 224 NSCLC patients who underwent preoperative 18F-FDG PET/CT scans in our hospital were collected. Then, a series of clinical parameters including SUV-derived features [SUVmax of mediastinal lymph node and primary-tumor SUVmax, SUVpeak, SUVmean, metabolic tumor volume (MTV) and total lesion glycolysis (TLG)] were evaluated. The best possible cutoff points for all measuring parameters were calculated using receiver operating characteristic curve (ROC) analysis. Predictive analyses were performed using a Logistic regression model to determine the predictive factors for mediastinal lymph node metastasis in NSCLC and lung adenocarcinoma patients. After multivariate model construction, data of another 100 NSCLC patients were recorded. Then, 224 patients and 100 patients were enrolled to validate the predictive model by the area under the receiver operating characteristic curve (AUC). RESULTS: The mediastinal lymph node metastasis rates in 224 patients for model construction and 100 patients for model validation were 24.1% (54/224) and 25% (25/100), respectively. It was found that SUVmax of mediastinal lymph node ≥ 2.49, primary-tumor SUVmax ≥ 4.11, primary-tumor SUVpeak ≥ 2.92, primary-tumor SUVmean ≥ 2.39, primary-tumor MTV ≥ 30.88 cm3, and primary-tumor TLG ≥ 83.53 were more prone to mediastinal lymph node metastasis through univariate logistic regression analyses. The multivariate logistic regression analyses showed that the SUVmax of mediastinal lymph nodes (≥ 2.49: OR 7.215, 95% CI 3.326-15.649), primary-tumor SUVpeak (≥ 2.92: OR 5.717, 95% CI 2.094-15.605), CEA (≥ 3.94 ng/ml: OR 2.467, 95% CI 1.182-5.149), and SCC (< 1.15 ng/ml: OR 4.795, 95% CI 2.019-11.388) were independent predictive factors for lymph node metastasis in the mediastinum. It was found that SUVmax of the mediastinal lymph node (≥ 2.49: OR 8.067, 95% CI 3.193-20.383), primary-tumor SUVpeak (≥ 2.92: OR 9.219, 95% CI 3.096-27.452), and CA19-9 (≥ 16.6 U/ml: OR 3.750, 95% CI 1.485-9.470) were significant predictive factors for mediastinal lymph node metastasis in lung adenocarcinoma patients. The AUCs for the predictive value of the NSCLC multivariate model through internal and external validation were 0.833 (95% CI 0.769- 0.896) and 0.811 (95% CI 0.712-0.911), respectively. CONCLUSION: High SUV-derived parameters (SUVmax of mediastinal lymph node and primary-tumor SUVmax, SUVpeak, SUVmean, MTV and TLG) might provide varying degrees of predictive value for mediastinal lymph node metastasis in NSCLC patients. In particular, the SUVmax of mediastinal lymph nodes and primary-tumor SUVpeak could be independently and significantly associated with mediastinal lymph node metastasis in NSCLC and lung adenocarcinoma patients. Internal and external validation confirmed that the pretherapeutic SUVmax of the mediastinal lymph node and primary-tumor SUVpeak combined with serum CEA and SCC can effectively predict mediastinal lymph node metastasis of NSCLC patients.

RTP4 inhibits IFN-I response and enhances experimental cerebral malaria and neuropathology.

Infection by malaria parasites triggers dynamic immune responses leading to diverse symptoms and pathologies; however, the molecular mechanisms responsible for these reactions are largely unknown. We performed Trans-species Expression Quantitative Trait Locus analysis to identify a large number of host genes that respond to malaria parasite infections. Here we functionally characterize one of the host genes called receptor transporter protein 4 (RTP4) in responses to malaria parasite and virus infections. RTP4 is induced by type I IFN (IFN-I) and binds to the TANK-binding kinase (TBK1) complex where it negatively regulates TBK1 signaling by interfering with expression and phosphorylation of both TBK1 and IFN regulatory factor 3. Rtp4-/- mice were generated and infected with malaria parasite Plasmodiun berghei ANKA. Significantly higher levels of IFN-I response in microglia, lower parasitemia, fewer neurologic symptoms, and better survival rates were observed in Rtp4-/- than in wild-type mice. Similarly, RTP4 deficiency significantly reduced West Nile virus titers in the brain, but not in the heart and the spleen, of infected mice, suggesting a specific role for RTP4 in brain infection and pathology. This study reveals functions of RTP4 in IFN-I response and a potential target for therapy in diseases with neuropathology.

The E3 ubiquitin ligase MARCH1 regulates antimalaria immunity through interferon signaling and T cell activation.

Malaria infection induces complex and diverse immune responses. To elucidate the mechanisms underlying host-parasite interaction, we performed a genetic screen during early (24 h) Plasmodium yoelii infection in mice and identified a large number of interacting host and parasite genes/loci after transspecies expression quantitative trait locus (Ts-eQTL) analysis. We next investigated a host E3 ubiquitin ligase gene (March1) that was clustered with interferon (IFN)-stimulated genes (ISGs) based on the similarity of the genome-wide pattern of logarithm of the odds (LOD) scores (GPLS). March1 inhibits MAVS/STING/TRIF-induced type I IFN (IFN-I) signaling in vitro and in vivo. However, in malaria-infected hosts, deficiency of March1 reduces IFN-I production by activating inhibitors such as SOCS1, USP18, and TRIM24 and by altering immune cell populations. March1 deficiency increases CD86+DC (dendritic cell) populations and levels of IFN-γ and interleukin 10 (IL-10) at day 4 post infection, leading to improved host survival. T cell depletion reduces IFN-γ level and reverse the protective effects of March1 deficiency, which can also be achieved by antibody neutralization of IFN-γ. This study reveals functions of MARCH1 (membrane-associated ring-CH-type finger 1) in innate immune responses and provides potential avenues for activating antimalaria immunity and enhancing vaccine efficacy.

Radioiodination, purification, and evaluation of antihuman tumor-derived immunoglobulin G light chain monoclonal antibody in tumor-bearing nude mice.

We report the synthesis and biological evaluation of 131 I-labeled antihuman tumor-derived immunoglobulin G (IgG) light chain monoclonal antibody (4E9) ([131 I]I-4E9) as a promising probe for tumor imaging. [131 I]I-4E9 was synthesized in radiochemical yield of 89.9 ± 4.7% with radiochemical purity of more than 99%. [131 I]I-4E9 showed high stability in normal saline and human serum. In cell uptake studies, [131 I]I-4E9 exhibited favorable binding affinity and high specificity in HeLa MR cells. In biodistribution studies, [131 I]I-4E9 showed high tumor uptake, high tumor/non-tumor ratios, and specific binding in BALB/c nu/nu mice bearing human HeLa MR xenografts. Single-photon emission computerized tomography (SPECT) imaging of [131 I]I-4E9 in the HeLa MR xenograft model demonstrated clear visualization of tumor after 48 h and confirmed specific binding in tumor. These findings suggest that [131 I]I-4E9 possesses favorable biological characteristics and warrants further investigation as a prospective probe for imaging and treatment of cancers.

LRRC25 inhibits type I IFN signaling by targeting ISG15-associated RIG-I for autophagic degradation.

The RIG-I-like receptors (RLRs) are critical for protection against RNA virus infection, and their activities must be stringently controlled to maintain immune homeostasis. Here, we report that leucine-rich repeat containing protein 25 (LRRC25) is a key negative regulator of RLR-mediated type I interferon (IFN) signaling. Upon RNA virus infection, LRRC25 specifically binds to ISG15-associated RIG-I to promote interaction between RIG-I and the autophagic cargo receptor p62 and to mediate RIG-I degradation via selective autophagy. Depletion of either LRRC25 or ISG15 abrogates RIG-I-p62 interaction as well as the autophagic degradation of RIG-I. Collectively, our findings identify a previously unrecognized role of LRRC25 in type I IFN signaling activation by which LRRC25 acts as a secondary receptor to assist RIG-I delivery to autophagosomes for degradation in a p62-dependent manner.

64Cu-labeled daratumumab F(ab')2 fragment enables early visualization of CD38-positive lymphoma.

PURPOSE: Abnormal CD38 expression in some hematologic malignancies, including lymphoma, has made it a biomarker for targeted therapies. Daratumumab (Dara) is the first FDA-approved CD38-specific monoclonal antibody, enabling successfully immunoPET imaging over the past years. Radiolabeled Dara however has a long blood circulation and delayed tumor uptake which can limit its applications. The focus of this study is to develop 64Cu-labeled Dara-F(ab')2 for the visualization of CD38 in lymphoma models. METHODS: F(ab')2 fragment was prepared from Dara using an IdeS enzyme and purified with Protein A beads. Western blotting, flow cytometry, and surface plasmon resonance (SPR) were performed for in vitro assay. Probes were labeled with 64Cu after the chelation of 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA). Small animal PET imaging and quantitative analysis were performed after injection of 64Cu-labeled Dara-F(ab')2, IgG-F(ab')2, and Dara for evaluation in lymphoma models. RESULTS: Flow cytometry and SPR assay proved the specific binding ability of Dara-F(ab')2 and NOTA-Dara-F(ab')2 in vitro. Radiolabeling yield of [64Cu]Cu-NOTA-Dara-F(ab')2 was over 90% and with a specific activity of 4.0 ± 0.6 × 103 MBq/µmol (n = 5). PET imaging showed [64Cu]Cu-NOTA-Dara-F(ab')2 had a rapid and high tumor uptake as early as 2 h (6.9 ± 1.2%ID/g) and peaked (9.5 ± 0.7%ID/g) at 12 h, whereas [64Cu]Cu-NOTA-Dara reached its tumor uptake peaked at 48 h (8.3 ± 1.4%ID/g, n = 4). In comparison, IgG-F(ab')2 and HBL-1 control groups found no noticeable tumor uptake. [64Cu]Cu-NOTA-Dara-F(ab')2 had significantly lower uptake in blood pool, bone, and muscle than [64Cu]Cu-NOTA-Dara and its tumor-to-blood and tumor-to-muscle ratios were significantly higher than controls. CONCLUSIONS: [64Cu]Cu-NOTA-Dara-F(ab')2 showed a rapid and high tumor uptake in CD38-positive lymphoma models with favorable imaging contrast, showing its promise as a potential PET imaging agent for future clinical applications.

Noninvasive Evaluation of Multidrug Resistance via Imaging of ABCG2/BCRP Multidrug Transporter in Lung Cancer Xenograft Models.

Chemotherapy is an important method for the treatment of lung cancer, but multidrug resistance (MDR) greatly reduces the efficacy. The superfamily of ATP-binding cassette (ABC) transport proteins is related to MDR. As a subfamily of ABC proteins, ABCG2/BCRP (breast cancer resistance protein, BCRP) is considered a major player in the development of cancer MDR. For the stratification of chemotherapeutic choices, we constructed Cy5.5- or 89Zr-labeled ABCG2-targeted monoclonal antibody (mAb) ABCG2-PKU1 for noninvasive evaluation of ABCG2 expression in lung cancer xenograft models. ABCG2 expression was screened in H460/MX (mitoxantrone resistant), H460, and H1299 human lung cancer cell lines using Western blotting. ELISA, flow cytometry, and cell immunofluorescent staining were used to evaluate the binding ability of ABCG2-PKU1 to ABCG2 antigen. Lung cancer murine xenograft models were built for in vivo experiments. ABCG2-PKU1 was labeled with Cy5.5 (Cy5.5-ABCG2) for fluorescent imaging and radiolabeled with 89Zr (89Zr-DFO-ABCG2) for immunoPET imaging following the conjugation with p-SCN-deferoxamine (DFO). In vivo imaging was performed in lung cancer models at 2, 24, 48, 72, 96, 120, 144, and 168 h postinjection. Ex vivo biodistribution was conducted after the terminal time point of imaging. Finally, tissue immunohistochemical staining was used to evaluate the tumor expression of ABCG2. Western blotting showed that the H460/MX cells had a high ABCG2 expression level whereas H460 and H1299 had moderate and low levels. ELISA, flow cytometry, and cell immunofluorescent staining results validated the good binding affinity between ABCG2-PKU1 and ABCG2. The H460/MX and H460 cells were used to build positive lung cancer models, and H1299 cells were used to build negative models. The fluorescent imaging showed that the tumor average radiant efficiency of Cy5.5-ABCG2 reached the maximum at 72 and 120 h in H460/MX and H460 respectively (n = 3, P < 0.01). The tumor uptake of Cy5.5-ABCG2 in H1299 (n = 3) was significantly lower than H460/MX and H460 (P < 0.01). ImmunoPET imaging showed that the tumor uptake of 89Zr-DFO-ABCG2 in H460/MX was significantly higher than H460, with a maximum of 4.15 ± 0.41 %ID/g and 2.81 ± 0.24 %ID/g at 168 and 144 h, respectively (n = 5, P < 0.01). The H1299 tumors showed significantly lower uptake than H460/MX and H460 (n = 5, P < 0.01). The radioactive uptake of 89Zr-DFO-ABCG2 among three groups in the heart, liver, and kidney gradually decreased over time. Ex vivo biodistribution verified the differential tumor uptake among the three groups (P < 0.01). Immunohistochemical staining revealed that the H460/MX tumor had the highest expression of ABCG2, whereas H460 and H1299 had the moderate and lowest expression, respectively. Therefore, in this study, fluorescent and immunoPET imaging of lung cancer MDR models using Cy5.5-ABCG2 and 89Zr-DFO-ABCG2 noninvasively evaluated the differential expression of ABCG2, which are expected to be used for the diagnosis and the selection for clinical treatment options for lung cancer MDR patients in future applications.

Telomerase therapy reverses vascular senescence and extends lifespan in progeria mice.

AIMS: Hutchinson-Gilford progeria syndrome (HGPS) is an accelerated ageing syndrome associated with premature vascular disease and death due to heart attack and stroke. In HGPS a mutation in lamin A (progerin) alters nuclear morphology and gene expression. Current therapy increases the lifespan of these children only modestly. Thus, greater understanding of the underlying mechanisms of HGPS is required to improve therapy. Endothelial cells (ECs) differentiated from induced pluripotent stem cells (iPSCs) derived from these patients exhibit hallmarks of senescence including replication arrest, increased expression of inflammatory markers, DNA damage, and telomere erosion. We hypothesized that correction of shortened telomeres may reverse these measures of vascular ageing. METHODS AND RESULTS: We generated ECs from iPSCs belonging to children with HGPS and their unaffected parents. Telomerase mRNA (hTERT) was used to treat HGPS ECs. Endothelial morphology and functions were assessed, as well as proteomic and transcriptional profiles with attention to inflammatory markers, DNA damage, and EC identity genes. In a mouse model of HGPS, we assessed the effects of lentiviral transfection of mTERT on measures of senescence, focusing on the EC phenotype in various organs. hTERT treatment of human HGPS ECs improved replicative capacity; restored endothelial functions such as nitric oxide generation, acetylated low-density lipoprotein uptake and angiogenesis; and reduced the elaboration of inflammatory cytokines. In addition, hTERT treatment improved cellular and nuclear morphology, in association with a normalization of the transcriptional profile, effects that may be mediated in part by a reduction in progerin expression and an increase in sirtuin 1 (SIRT1). Progeria mice treated with mTERT lentivirus manifested similar improvements, with a reduction in inflammatory and DNA damage markers and increased SIRT1 in their vasculature and other organs. Furthermore, mTERT therapy increased the lifespan of HGPS mice. CONCLUSION: Vascular rejuvenation using telomerase mRNA is a promising approach for progeria and other age-related diseases.

ImmunoPET of CD146 in Orthotopic and Metastatic Breast Cancer Models.

The overexpression of CD146 in breast cancer is considered a hallmark of tumor progression and metastasis, particularly in triple negative breast cancer. Aimed at imaging differential CD146 expressions in breast cancer, a noninvasive method for predictive prognosis and diagnosis was investigated using a 64Cu-labeled CD146-specific monoclonal antibody, YY146. CD146 expression was screened in human breast cancer cell lines using Western blotting. Binding ability was evaluated using flow cytometry and immunofluorescent staining. YY146 was conjugated with 1,4,7-triazacyclononane-triacetic acid (NOTA) and radiolabeled with 64Cu following standard procedures. Serial PET or PET/CT imaging was performed in orthotopic and metastatic breast cancer tumor models. Biodistribution was performed after the final time point of imaging. Finally, tissue immunofluorescent staining and hematoxylin and eosin (H&E) staining were performed on tumor tissues. The MDA-MB-435 cell line showed the highest CD146 expression level, whereas MCF-7 had the lowest level at the cellular level. ImmunoPET showed that MDA-MB-435 orthotopic tumors had high and clear radioactive accumulation after the administration of 64Cu-NOTA-YY146. The tumor uptake of 64Cu-NOTA-YY146 in MDA-MB-435 was significantly higher than that in MCF-7 and nonspecific IgG control groups (P < 0.01). Biodistribution verified the PET imaging results. For metastatic models, 64Cu-NOTA-YY146 allowed for the visualization of high radioactivity accumulation in metastatic MDA-MB-435 tumors, which was confirmed by ex vivo biodistribution of lung tissues. H&E staining proved the successful building of metastatic tumor models. Immunofluorescent staining verified the differential expression of CD146 in orthotopic tumors. Therefore, 64Cu-NOTA-YY146 could be used as an immunoPET probe to visualize CD146 in the breast cancer model and is potentially useful for cancer diagnosis, prognosis prediction, and monitoring therapeutic response.

TAK1 negatively regulates NF-κB and p38 MAP kinase activation in Gr-1+CD11b+ neutrophils.

Stringent control of NF-κB and mitogen-activated protein kinase (MAPK) signaling is critical during innate immune responses. TGF-ß activated kinase-1 (TAK1) is essential for NF-κB activation in T and B cells but has precisely the opposite activity in myeloid cells. Specific deletion of TAK1 (Map3k7(ΔM/ΔM)) led to development of splenomegaly and lymphomegaly associated with neutrophilia. Compared with wild-type cells, TAK1-deficient neutrophils enhanced the phosphorylation of the kinases IKK, p38, and JNK and the production of interleukin-1ß (IL-1ß), IL-6, tumor necrosis factor-α (TNF-α), and reactive oxygen species (ROS) after lipopolysaccharide (LPS) stimulation. Map3k7(ΔM/ΔM) mice were significantly more susceptible to LPS-induced septic shock and produced higher amounts of IL-1ß, IL-6, and TNF-α in plasma than do wild-type mice. Specific ablation of p38 rescued the phenotype and functional properties of Map3k7(ΔM/ΔM) mice. Our findings identify a previously unrecognized role of TAK1 as a negative regulator of p38 and IKK activation in a cell type-specific manner.

Arginine-Arginine-Leucine Peptide Targeting Heat Shock Protein 70 for Cancer Imaging.

Arg-Arg-Leu (RRL) is a potent tumor-homing tripeptide. However, the binding target is unclear. In this study, we intended to identify the binding target of RRL and evaluate the tumor targeting of 99mTc-MAG3-RRL in vivo. Biotin-RRL, 5-TAMRA-RRL, and 99mTc-MAG3-RRL were designed to trace the binding target and tumor lesion. Immunoprecipitation-mass spectrometry was conducted to identify the candidate proteins and determination of the subcellular localization was also performed. A pull-down assay was performed to demonstrate the immunoprecipitate. Fluorescence colocalization and cell uptake assays were performed to elucidate the correlation between the selected binding protein and RRL, and the internalization mechanism of RRL. Biodistribution and in vivo imaging were performed to evaluate the tumor accumulation and targeting of 99mTc-MAG3-RRL. The target for RRL was screened to be heat shock protein 70 (HSP70). The prominent uptake distribution of RRL was concentrated in the membrane and cytoplasm. A pull-down assay demonstrated the existence of HSP70 in the biotin-RRL captured complex. Regarding fluorescence colocalization and cell uptake assays, RRL may interact with HSP70 at the nucleotide-binding domain (NBD). Clathrin-dependent endocytosis and macropinocytosis could be a vital internalization mechanism of RRL. In vivo imaging and biodistribution both demonstrated that 99mTc-MAG3-RRL can trace tumors with satisfactory accumulation in hepatoma xenograft mice. The radioactive signals accumulated in tumor lesions can be blocked by VER-155008, which can bind to the NBD of HSP70. Our findings revealed that RRL may interact with HSP70 and that 99mTc-MAG3-RRL could be a prospective probe for visualizing overexpressed HSP70 tumor sections.