Nanobody-siRNA Conjugates for Targeted Delivery of siRNA to Cancer Cells.

Targeted extrahepatic delivery of siRNA remains a challenging task in the field of nucleic acid therapeutics. An ideal delivery tool must internalize siRNA exclusively into the cells of interest without affecting the silencing activity of siRNA. Here, we report the use of anti-EGFR Nanobodies (trademark of Ablynx N.V.) as tools for targeted siRNA delivery. A straightforward procedure for site-specific conjugation of siRNA to an engineered C-terminal cysteine residue on the Nanobody (trademark of Ablynx N.V.) is described. We show that siRNA-conjugated Nanobodies (Nb-siRNA) retain their binding to EGFR and enter EGFR-positive cells via receptor-mediated endocytosis. The activity of Nb-siRNAs was assessed by measuring the knockdown of a housekeeping gene (AHSA1) in EGFR-positive and EGFR-negative cells. We demonstrate that Nb-siRNAs are active in vitro and induce mRNA cleavage in the targeted cell line. In addition, we discuss the silencing activity of siRNA conjugated to fused Nbs with various combinations of EGFR-binding building blocks. Finally, we compare the performance of Nb-siRNA joined by four different linkers and discuss the advantages and limitations of using cleavable and noncleavable linkers in the context of Nanobody-mediated siRNA delivery.

Engagement of community stakeholders to develop a framework to guide research dissemination to communities.

BACKGROUND: Dissemination of research findings to past study participants and the community-at-large is important. Yet, a standardized process for research dissemination is needed to report results to the community. OBJECTIVE: We developed a framework and strategies to guide community-academic partnerships in community-targeted, dissemination efforts. METHODS: From 2017 to 2019, a community-academic partnership was formed in Nashville, Tennessee, and iteratively developed a framework and strategies for research dissemination using cognitive interviews. A deductive, constant comparative analysis was conducted on interview responses to examine framework and strategy content. Feedback was used to finalize the framework and strategies for the evaluation. Using existing data, the framework's utility was evaluated in seven town hall meetings (n = 117). Bivariate analyses determined its effect on community members' trust and willingness to participate in research using pre- and post-surveys. Evaluation results were used to finalize the framework. RESULTS: The Community-Engaged Research Dissemination (CERD) framework has two phases. Phase one is a preliminary planning phase with two steps, and phase two is the four-step dissemination process. There are five standards to be upheld conducting these phases. We provide competencies for each component. Three feasible, culturally adapted strategies were developed as exemplars to disseminate research findings. Using pre- and post-surveys for intervention evaluation, there was a significant difference in trust in medical research and researchers (P = .006) and willingness to participate in research (P = .013). DISCUSSION AND CONCLUSION: The CERD framework can potentially standardize the process and compare the effect of dissemination efforts on the community's trust and willingness to participate in research.

Epigenetic and Transcriptional Regulation of IRAK-M Expression in Macrophages.

During macrophage activation, expression of IL-1R-associated kinase (IRAK)-M is induced to suppress TLR-mediated responses and is a hallmark of endotoxin tolerance. Endotoxin tolerance requires tight regulation of genes occurring at the transcriptional and epigenetic levels. To identify novel regulators of IRAK-M, we used RAW 264.7 macrophages and performed a targeted RNA interference screen of genes encoding chromatin-modifying enzymes, signaling molecules, and transcription factors involved in macrophage activation. Among these, the transcription factor CCAAT/enhancer binding protein (C/EBP)ß, known to be involved in macrophage inactivation, was necessary for the induction of IRAK-M expression. Chromatin immunoprecipitation showed that C/EBPß was recruited to the IRAK-M promoter following LPS stimulation and was indispensable for IRAK-M transcriptional activation. Among histone 3-modifying enzymes, our screen showed that knockdown of the histone 3 lysine 27 (H3K27) methyltransferase and part of the polycomb recessive complex 2, enhancer of Zeste 2, resulted in IRAK-M overexpression. In contrast, knockdown of the H3K27 demethylase ubiquitously transcribed tetratricopeptide repeat X chromosome suppressed the induction of IRAK-M in response to LPS stimulation. Accordingly, we demonstrated that H3K27 on the IRAK-M promoter is trimethylated in unstimulated cells and that this silencing epigenetic mark is removed upon LPS stimulation. Our data propose a mechanism for IRAK-M transcriptional regulation according to which, in the naive state, polycomb recessive complex 2 repressed the IRAK-M promoter, allowing low levels of expression; following LPS stimulation, the IRAK-M promoter is derepressed, and transcription is induced to allow its expression.

Akt2 deficiency protects from acute lung injury via alternative macrophage activation and miR-146a induction in mice.

Acute respiratory distress syndrome (ARDS) is a major cause of respiratory failure, with limited effective treatments available. Alveolar macrophages participate in the pathogenesis of ARDS. To investigate the role of macrophage activation in aseptic lung injury and identify molecular mediators with therapeutic potential, lung injury was induced in wild-type (WT) and Akt2(-/-) mice by hydrochloric acid aspiration. Acid-induced lung injury in WT mice was characterized by decreased lung compliance and increased protein and cytokine concentration in bronchoalveolar lavage fluid. Alveolar macrophages acquired a classical activation (M1) phenotype. Acid-induced lung injury was less severe in Akt2(-/-) mice compared with WT mice. Alveolar macrophages from acid-injured Akt2(-/-) mice demonstrated the alternative activation phenotype (M2). Although M2 polarization suppressed aseptic lung injury, it resulted in increased lung bacterial load when Akt2(-/-) mice were infected with Pseudomonas aeruginosa. miR-146a, an anti-inflammatory microRNA targeting TLR4 signaling, was induced during the late phase of lung injury in WT mice, whereas it was increased early in Akt2(-/-) mice. Indeed, miR-146a overexpression in WT macrophages suppressed LPS-induced inducible NO synthase (iNOS) and promoted M2 polarization, whereas miR-146a inhibition in Akt2(-/-) macrophages restored iNOS expression. Furthermore, miR-146a delivery or Akt2 silencing in WT mice exposed to acid resulted in suppression of iNOS in alveolar macrophages. In conclusion, Akt2 suppression and miR-146a induction promote the M2 macrophage phenotype, resulting in amelioration of acid-induced lung injury. In vivo modulation of macrophage phenotype through Akt2 or miR-146a could provide a potential therapeutic approach for aseptic ARDS; however, it may be deleterious in septic ARDS because of impaired bacterial clearance.

Small Interfering RNAs Containing Dioxane- and Morpholino-Derived Nucleotide Analogues Show Improved Off-Target Profiles and Chirality-Dependent In Vivo Knock-Down.

To expand the applicability of recently developed dioxane- and morpholino-based nucleotide analogues, their seed region destabilizing properties in small interfering RNAs (siRNAs) were investigated in order to improve potential off-target profiles. For this purpose, the corresponding adenosine analogues were synthesized in two diastereomeric series as building blocks for the automated oligonucleotide synthesis. The obtained nucleotide precursors were integrated at position 7 of an siRNA antisense strand, targeting transthyretin messenger RNA. Evaluation of the melting temperatures revealed significant differences in the obtained duplex stabilities between the two diastereomeric series, while the influence of the central scaffold was small. All siRNAs containing these novel nucleotide structures showed improved off-target profiles in vitro compared to their parent sequence with the common 2'-OMe-modified adenosine at the same position. In contrast, in vivo potencies were highly dependent on the chirality within the six-membered nucleotide scaffolds and showed high mRNA downregulations for the (2R,6R)-configured diastereomers.

Syntheses of Morpholine-Based Nucleotide Analogs for Hepatic siRNA Targeting and Stabilization.

A morpholine-based nucleotide analog was developed as a building block for hepatic siRNA targeting and stabilization. Attachment of an asialoglycoprotein-binding GalNAc ligand at the morpholine nitrogen was realized with different linkers. The obtained morpholino GalNAc scaffolds were coupled to the sense strand of a transthyretin-targeting siRNA and tested for their knockdown potency in vitro and in vivo. A clear structure-activity relationship was developed with regard to the linker type and length as well as the attachment site of the morpholino GalNAc moieties at the siRNA sense strand. Further, simple alkylation of the morpholine nitrogen led to a nucleotide analog, which increased siRNA stability, when used as a double 3'-overhang at the sense strand sequence. Combination of the best morpholino GalNAc building blocks as targeting nucleotides with an optimized stabilizing alkyl-substituted morpholine as 3'-overhangs resulted in siRNAs without any phosphorothioate stabilization in the sense strand and clearly improved the duration of action in vivo.

IL-12 enhances efficacy and shortens enrichment time in cytokine-induced killer cell immunotherapy.

Cytokine-induced killer (CIK) cells are T cell derived ex vivo expanded cells with both NK and T cell properties. They exhibit potent anti-tumor efficacy against various malignancies in preclinical models and have proven safe and effective in clinical studies. We combined CIK cell adoptive immunotherapy with IL-12 cytokine immunotherapy in an immunocompetent preclinical breast cancer model. Combining CIK cells with IL-12 increased anti-tumor efficacy in vivo compared to either therapy alone. Combination led to full tumor remission and long-term protection in 75% of animals. IL-12 treatment sharply increased the anti-tumor efficacy of short-term cultured CIK cells that exhibited no therapeutic effect alone. Bioluminescence imaging based in vitro cytotoxicity and in vivo homing assays revealed that short-term cultured CIK cells exhibit full cytotoxicity in vitro, but display different tumor homing properties than fully expanded CIK cells in vivo. Our data suggest that short-term cultured CIK cells can be "educated" in vivo, producing fully expanded CIK cells upon IL-12 administration with anti-tumor efficacy in a mouse model. Our findings demonstrate the potential to improve current CIK cell-based immunotherapy by increasing efficacy and shortening ex vivo expansion time. This holds promise for a highly efficacious cancer therapy utilizing synergistic effects of cytokine and cellular immunotherapy.

Triantennary GalNAc Molecular Imaging Probes for Monitoring Hepatocyte Function in a Rat Model of Nonalcoholic Steatohepatitis.

Nonalcoholic steatohepatitis (NASH) is a progressive form of nonalcoholic fatty liver disease that can lead to irreversible liver cirrhosis and cancer. Early diagnosis of NASH is vital to detect disease before it becomes life-threatening, yet noninvasively differentiating NASH from simple steatosis is challenging. Herein, bifunctional probes have been developed that target the hepatocyte-specific asialoglycoprotein receptor (ASGPR), the expression of which decreases during NASH progression. The results show that the probes allow longitudinal, noninvasive monitoring of ASGPR levels by positron emission tomography in the newly developed rat model of NASH. The probes open new possibilities for research into early diagnosis of NASH and development of drugs to slow or reverse its progression.

Quantifying cell-surface biomarker expression in thick tissues with ratiometric three-dimensional microscopy.

The burgeoning fields of in vivo three-dimensional (3D) microscopy and endomicroscopy, as well as ex vivo tissue cytometry have introduced new challenges for tissue preparation and staining with exogenous molecular contrast agents. These challenges include effective delivery of the agents, and once delivered, distinguishing between bound verses unbound molecular probes. If applied topically, there are additional issues with rinsing off unbound probe, which can be nonuniform and inefficient in thick tissues, thus leading to ambiguous contrast and a large nonspecific background that may obscure molecule-specific staining. Therefore, we have developed a ratiometric 3D microscopy scheme that not only reduces the effects of nonspecific sources of contrast, but also enables quantification of the relative binding affinity of imaging probes to their biomarker targets. Here we demonstrate this ratiometric approach by simultaneously imaging a HER2/neu (erbB2)-targeted monoclonal antibody labeled with one fluorophore and an isotype-matched negative control antibody labeled with another fluorophore. By taking a pixel-by-pixel calibrated ratio between the signals from each fluorescent image channel, accurate quantification of specific versus nonspecific binding affinity is achieved with cultured cells, yielding data that are in agreement with analyses via flow cytometry. We also demonstrate quantitative 3D microscopic imaging of biomarker expression in tissue models and in thick human biopsy samples of normal, HER2-negative, and HER2-positive breast tumors. This strategy enables rapid, quantitative, and unambiguous volumetric microscopy of biomarker expression in thick tissues, including whole biopsies, and will enable real-time optical assessment of disease markers in the living body.

Utility of the RIG-I Agonist Triphosphate RNA for Melanoma Therapy.

The pattern recognition receptor RIG-I plays an important role in the recognition of nonself RNA and antiviral immunity. RIG-I's natural ligand, triphosphate RNA (ppp-RNA), is proposed to be a valuable addition to the growing arsenal of cancer immunotherapy treatment options. In this study, we present comprehensive data validating the concept and utility of treatment with synthetic RIG-I agonist ppp-RNA for the therapy of human cancer, with melanoma as potential entry indication amenable to intratumoral treatment. Using mRNA expression data of human tumors, we demonstrate that RIG-I expression is closely correlated to cellular and cytokine immune activation in a wide variety of tumor types. Furthermore, we confirm susceptibility of cancer cells to ppp-RNA treatment in different cellular models of human melanoma, revealing unexpected heterogeneity between cell lines in their susceptibility to RNA agonist features, including sequence, secondary structures, and presence of triphosphate. Cellular responses to RNA treatment (induction of type I IFN, FasR, MHC-I, and cytotoxicity) were demonstrated to be RIG-I dependent using KO cells. Following ppp-RNA treatment of a mouse melanoma model, we observed significant local and systemic antitumor effects and survival benefits. These were associated with type I IFN response, tumor cell apoptosis, and innate and adaptive immune cell activation. For the first time, we demonstrate systemic presence of tumor antigen-specific CTLs following treatment with RIG-I agonists. Despite potential challenges in the generation and formulation of potent RIG-I agonists, ppp-RNA or analogues thereof have the potential to play an important role for cancer treatment in the next wave of immunotherapy.

Oncogenic dependency on ß-catenin in liver cancer cell lines correlates with pathway activation.

Hepatocellular carcinoma (HCC) represents a serious public health challenge with few therapeutic options available to cancer patients.Wnt/ß-catenin pathway is thought to play a significant role in HCC pathogenesis. In this study, we confirmed high frequency of CTNNB1 (ß-catenin) mutations in two independent cohorts of HCC patients and demonstrated significant upregulation of ß-catenin protein in the overwhelming majority of HCC patient samples, patient-derived xenografts (PDX) and established cell lines. Using genetic tools validated for target specificity through phenotypic rescue experiments, we went on to investigate oncogenic dependency on ß-catenin in an extensive collection of human HCC cells lines. Our results demonstrate that dependency on ß-catenin generally tracks with its activation status. HCC cell lines that harbored activating mutations in CTNNB1 or displayed elevated levels of non-phosphorylated (active) ß-catenin were significantly more sensitive to ß-catenin siRNA treatment than cell lines with wild-type CTNNB1 and lower active ß-catenin. Finally, significant therapeutic benefit of ß-catenin knock-down was demonstrated in established HCC tumor xenografts using doxycycline-inducible shRNA system. ß-catenin downregulation and tumor growth inhibition was associated with reduction in AXIN2, direct transcriptional target of ß-catenin, and decreased cancer cell proliferation as measured by Ki67 staining. Taken together, our data highlight fundamental importance of aberrant ß-catenin signaling in the maintenance of oncogenic phenotype in HCC.

Options for visualizing metastatic disease in the living body.

Detection and observation of primary tumor growth and metastasis in living subjects is an important task in clinical and basic cancer research. Recently several approaches and techniques emerged which offer a huge variety of options with respect to the specific objectives and questions of a given study. Recent developments in the field of in vivo imaging not only allow the assessment of anatomic information but also functional processes with cellular resolution and molecular sensitivity. This chapter will provide an overview of the most common imaging techniques which are currently available for the detection and observation of metastasizing tumor cells. General capacities, advantages, limitations and drawbacks will be discussed. These techniques include computed tomography (CT), molecular resonance imaging (MRI), positron emission tomography (PET), single photon emission computed tomography (SPECT), fluorescence imaging (FI), and bioluminescent imaging (BLI). The objective is to provide the cancer researcher with information that will help solve the dilemma of how best to apply the latest imaging tools for studying biological questions in the context of the living body.

Activation mechanism of pro-astacin: role of the pro-peptide, tryptic and autoproteolytic cleavage and importance of precise amino-terminal processing.

Astacin (EC 3.4.24.21) is a prototype for the astacin family and for the metzincin superfamily of zinc peptidases, which comprise membrane-bound and secreted enzymes involved in extracellular proteolysis during tissue development and remodelling. Generally, metzincins are translated as pro-enzymes (zymogens), which are activated by removal of an N-terminal pro-peptide. In astacin, however, the mode of zymogen activation has been obscured, since the pro-form does not accumulate in vivo. Here we report the detection of pro-astacin in midgut glands of brefeldin A-treated crayfish (Astacus astacus) by immunoprecipitation and mass spectrometry. We demonstrate that the pro-peptide is able to shield the active site of mature astacin as a transient inhibitor, which is degraded slowly. In vitro studies with recombinant pro-astacin in the absence of another protease reveal a potential of auto-proteolytic activation. The initial cleavage in this autoactivation appears to be an intramolecular event. This is supported by the fact that the mutant E93A-pro-astacin is incapable of autoactivation, and completely resistant to cleavage by mature astacin. However, this mutant is cleaved by Astacus trypsin within the pro-peptide. This probably reflects the in vivo situation, where Astacus trypsin and astacin work together during pro-astacin activation. In a first step, trypsin produces amino-terminally truncated pro-astacin derivatives. These are trimmed subsequently by each other and by astacin to yield the mature amino terminus, which forms a salt-bridge with Glu103 in the active site. The disruption of this salt-bridge in the mutants E103A and E103Q results in extremely heat labile proteins, whose catalytic activities are not altered drastically, however. This supports a concept according to which the linkage of Glu103 to the precisely trimmed amino terminus is a crucial structural prerequisite throughout the astacin family.

Image-guided genomic analysis of tissue response to laser-induced thermal stress.

The cytoprotective response to thermal injury is characterized by transcriptional activation of "heat shock proteins" (hsp) and proinflammatory proteins. Expression of these proteins may predict cellular survival. Microarray analyses were performed to identify spatially distinct gene expression patterns responding to thermal injury. Laser injury zones were identified by expression of a transgene reporter comprised of the 70 kD hsp gene and the firefly luciferase coding sequence. Zones included the laser spot, the surrounding region where hsp70-luc expression was increased, and a region adjacent to the surrounding region. A total of 145 genes were up-regulated in the laser irradiated region, while 69 were up-regulated in the adjacent region. At 7 hours the chemokine Cxcl3 was the highest expressed gene in the laser spot (24 fold) and adjacent region (32 fold). Chemokines were the most common up-regulated genes identified. Microarray gene expression was successfully validated using qRT- polymerase chain reaction for selected genes of interest. The early response genes are likely involved in cytoprotection and initiation of the healing response. Their regulatory elements will benefit creating the next generation reporter mice and controlling expression of therapeutic proteins. The identified genes serve as drug development targets that may prevent acute tissue damage and accelerate healing.

TOB1 is regulated by EGF-dependent HER2 and EGFR signaling, is highly phosphorylated, and indicates poor prognosis in node-negative breast cancer.

Clinical and animal studies have shown that coexpression of the receptor tyrosine kinases HER2 and epidermal growth factor (EGF) receptor (EGFR) indicates a highly metastatic phenotype of breast cancer. In a cellular model of this phenotype using differential gene expression analysis, we identified TOB1 to be up-regulated depending on EGF stimulation and transduction through phosphorylation of HER2 tyrosine 1248. mRNA expression analysis of breast cancers from a cohort of node-negative patients showed significantly shortened distant metastasis-free survival for patients with high TOB1 expression. In subsequent tissue microarray studies of 725 clinical samples, high HER2 and EGF protein levels were significantly correlated with TOB1 expression in breast cancer, whereas EGFR and EGF levels correlated with TOB1 phosphorylation. We did not observe a correlation between TOB1 expression and cyclin D1, which was previously suggested to mediate the antiproliferative effect of unphosphorylated TOB1. A positive correlation of TOB1 phosphorylation status with proliferation marker Ki67 suggests that elevated TOB1 phosphorylation might abrogate the antiproliferative effect of TOB1 in breast cancer. This suggests a new regulatory role for TOB1 in cancer progression with particular significance in HER2- and/or EGFR-positive breast cancers.

First evidence supporting a potential role for the BMP/SMAD pathway in the progression of oestrogen receptor-positive breast cancer.

Oestrogen receptor expression is generally a sign of better tumour differentiation and comparatively good clinical outcome in invasive breast cancer. However, oestrogen receptor-positive, poorly differentiated carcinomas with a poor clinical outcome exist. The underlying genetic mechanisms and the genes involved remain obscure, even though chromosome 7p gains seem to be associated with these uncommon tumours. In this study, we compared two subsets of oestrogen receptor-positive breast cancers, which differed in tumour grade, cytogenetic instability, and tumour proliferation, for their differential gene expression in order to identify proteins involved in the progression of oestrogen receptor-positive breast cancers. We were able to show by means of subtractive suppression hybridization, real-time reverse transcriptase PCR, and tissue microarray analysis that expression of the bone morphogenetic protein receptor IB (BMPR-IB) is a major hallmark of the progression and dedifferentiation of breast cancer. Strong expression of BMPR-IB was associated with high tumour grade, high tumour proliferation, cytogenetic instability, and a poor prognosis in oestrogen receptor-positive carcinomas. Western blot analysis revealed that downstream signalling of this receptor is mainly mediated via phosphorylation of SMAD 1 in oestrogen receptor-positive breast cancer. Even though BMPR-IB was expressed in oestrogen receptor-positive and -negative breast cancers, an impact on tumour grade, proliferation, and cytogenetic instability, as parameters of tumour progression, could only be demonstrated in oestrogen receptor-positive carcinomas. This pro-proliferative effect was complemented by significant anti-apoptotic activity, indicated by XIAP and IAP-2 expression in BMPR-IB-positive carcinomas. These results show that the BMP/SMAD pathway is activated in breast cancer and may contribute to breast cancer progression and dedifferentiation in oestrogen receptor-positive breast cancer. The definition of this pathway characterizes a new potential target in the molecular treatment of invasive breast cancer.