A novel micropeptide, Slitharin, exerts cardioprotective effects in myocardial infarction

PURPOSE

Micropeptides are an emerging class of proteins that play critical roles in cell signaling. Here, we describe the discovery of a novel micropeptide, dubbed slitharin (Slt), in conditioned media from Cardiosphere-derived cells (CDCs), a therapeutic cardiac stromal cell type.

EXPERIMENTAL DESIGN

We performed mass spectrometry of peptide-enriched fractions from the conditioned media of CDCs and a therapeutically inert cell type (human dermal fibrobasts). We then evaluated the therapeutic capacity of the candidate peptide using an in vitro model of cardiomyocyte injury and a rat model of myocardial infarction.

RESULTS

We identified a novel 24-amino acid micropeptide (dubbed Slitharin [Slt]) with a non-canonical leucine start codon, arising from long intergenic non-coding (LINC) RNA 2099. Neonatal rat ventricular myocytes (NRVMs) exposed to Slt were protected from hypoxic injury in vitro compared to a vehicle or scrambled control. Transcriptomic analysis of cardiomyocytes exposed to Slt reveals cytoprotective capacity, putatively through regulation of stress-induced MAPK-ERK. Slt also exerted cardioprotective effects in rats with myocardial infarction as shown by reduced infarct size 48 h post-injury. Conclusions and clinical relavance: Thus, Slt is a non-coding RNA-derived micropeptide, identified in the extracellular space, with a potential cardioprotective function.

Targeting prostate tumor low-molecular weight tyrosine phosphatase for oxidation-sensitizing therapy

Protein tyrosine phosphatases (PTPs) play major roles in cancer and are emerging as therapeutic targets. Recent reports suggest low-molecular weight PTP (LMPTP)-encoded by the ACP1 gene-is overexpressed in prostate tumors. We found ACP1 up-regulated in human prostate tumors and ACP1 expression inversely correlated with overall survival. Using CRISPR-Cas9-generated LMPTP knockout C4-2B and MyC-CaP cells, we identified LMPTP as a critical promoter of prostate cancer (PCa) growth and bone metastasis. Through metabolomics, we found that LMPTP promotes PCa cell glutathione synthesis by dephosphorylating glutathione synthetase on inhibitory Tyr270. PCa cells lacking LMPTP showed reduced glutathione, enhanced activation of eukaryotic initiation factor 2-mediated stress response, and enhanced reactive oxygen species after exposure to taxane drugs. LMPTP inhibition slowed primary and bone metastatic prostate tumor growth in mice. These findings reveal a role for LMPTP as a critical promoter of PCa growth and metastasis and validate LMPTP inhibition as a therapeutic strategy for treating PCa through sensitization to oxidative stress.

Sumoylation of methionine adenosyltransferase alpha 1 promotes mitochondrial dysfunction in alcohol-associated liver disease

BACKGROUND AND AIMS

Methionine adenosyltransferase alpha1 (MATα1) is responsible for the biosynthesis of S-adenosylmethionine in normal liver. Alcohol consumption enhances MATα1 interaction with peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (PIN1), which blocks MATα1 mitochondrial targeting, resulting in lower mitochondrial MATα1 content and mitochondrial dysfunction in alcohol-associated liver disease (ALD) in part through upregulation of cytochrome P450 2E1. Conversely, alcohol intake enhances SUMOylation, which enhances cytochrome P450 2E1 expression. MATα1 has potential SUMOylation sites, but whether MATα1 is regulated by SUMOylation in ALD is unknown. Here, we investigated if MATα1 is regulated by SUMOylation and, if so, how it impacts mitochondrial function in ALD.

APPROACH AND RESULTS

Proteomics profiling revealed hyper-SUMOylation of MATα1, and prediction software identified lysine 48 (K48) as the potential SUMOylation site in mice (K47 in humans). Experiments with primary hepatocytes, mouse, and human livers revealed that SUMOylation of MAT1α by SUMO2 depleted mitochondrial MATα1. Furthermore, mutation of MATα1 K48 prevented ethanol-induced mitochondrial membrane depolarization, MATα1 depletion, and triglyceride accumulation. Additionally, CRISPR/CRISPR associated protein 9 gene editing of MATα1 at K48 hindered ethanol-induced MATα1-PIN1 interaction, degradation, and phosphorylation of MATα1 in vitro. In vivo, CRISPR/CRISPR associated protein 9 MATα1 K48 gene-edited mice were protected from ethanol-induced fat accumulation, liver injury, MATα1-PIN1 interaction, mitochondrial MATα1 depletion, mitochondrial dysfunction, and low S-adenosylmethionine levels.

CONCLUSIONS

Taken together, our findings demonstrate an essential role for SUMOylation of MATα1 K48 for interaction with PIN1 in ALD. Preventing MATα1 K48 SUMOylation may represent a potential treatment strategy for ALD.

Functional divergence of a bacterial enzyme promotes healthy or acneic skin

Acne is a dermatologic disease with a strong pathologic association with human commensal Cutibacterium acnes. Conspicuously, certain C. acnes phylotypes are associated with acne, whereas others are associated with healthy skin. Here we investigate if the evolution of a C. acnes enzyme contributes to health or acne. Two hyaluronidase variants exclusively expressed by C. acnes strains, HylA and HylB, demonstrate remarkable clinical correlation with acne or health. We show that HylA is strongly pro-inflammatory, and HylB is modestly anti-inflammatory in a murine (female) acne model. Structural and phylogenic studies suggest that the enzymes evolved from a common hyaluronidase that acquired distinct enzymatic activity. Health-associated HylB degrades hyaluronic acid (HA) exclusively to HA disaccharides leading to reduced inflammation, whereas HylA generates large-sized HA fragments that drive robust TLR2-dependent pathology. Replacing an amino acid, Serine to Glycine near the HylA catalytic site enhances the enzymatic activity of HylA and produces an HA degradation pattern intermediate to HylA and HylB. Selective targeting of HylA using peptide vaccine or inhibitors alleviates acne pathology. We suggest that the functional divergence of HylA and HylB is a major driving force behind C. acnes health- and acne- phenotype and propose targeting of HylA as an approach for acne therapy.

Genetic coding variant in complement factor B (CFB) is associated with increased risk for perianal Crohn's disease and leads to impaired CFB cleavage and phagocytosis

OBJECTIVE

Perianal Crohn's disease (pCD) occurs in up to 40% of patients with CD and is associated with poor quality of life, limited treatment responses and poorly understood aetiology. We performed a genetic association study comparing CD subjects with and without perianal disease and subsequently performed functional follow-up studies for a pCD associated SNP in Complement Factor B (CFB).

DESIGN

Immunochip-based meta-analysis on 4056 pCD and 11 088 patients with CD from three independent cohorts was performed. Serological and clinical variables were analysed by regression analyses. Risk allele of rs4151651 was introduced into human CFB plasmid by site-directed mutagenesis. Binding of recombinant G252 or S252 CFB to C3b and its cleavage was determined in cell-free assays. Macrophage phagocytosis in presence of recombinant CFB or serum from CFB risk, or protective CD or healthy subjects was assessed by flow cytometry.

RESULTS

Perianal complications were associated with colonic involvement, OmpC and ASCA serology, and serology quartile sum score. We identified a genetic association for pCD (rs4151651), a non-synonymous SNP (G252S) in CFB, in all three cohorts. Recombinant S252 CFB had reduced binding to C3b, its cleavage was impaired, and complement-driven phagocytosis and cytokine secretion were reduced compared with G252 CFB. Serine 252 generates a de novo glycosylation site in CFB. Serum from homozygous risk patients displayed significantly decreased macrophage phagocytosis compared with non-risk serum.

CONCLUSION

pCD-associated rs4151651 in CFB is a loss-of-function mutation that impairs its cleavage, activation of alternative complement pathway, and pathogen phagocytosis thus implicating the alternative complement pathway and CFB in pCD aetiology.

ONECUT2 Activates Diverse Resistance Drivers of Androgen Receptor-Independent Heterogeneity in Prostate Cancer

Androgen receptor- (AR-) indifference is a mechanism of resistance to hormonal therapy in prostate cancer (PC). Here we demonstrate that the HOX/CUT transcription factor ONECUT2 (OC2) activates resistance through multiple drivers associated with adenocarcinoma, stem-like and neuroendocrine (NE) variants. Direct OC2 targets include the glucocorticoid receptor and the NE splicing factor SRRM4, among others. OC2 regulates gene expression by promoter binding, enhancement of chromatin accessibility, and formation of novel super-enhancers. OC2 also activates glucuronidation genes that irreversibly disable androgen, thereby evoking phenotypic heterogeneity indirectly by hormone depletion. Pharmacologic inhibition of OC2 suppresses lineage plasticity reprogramming induced by the AR signaling inhibitor enzalutamide. These results demonstrate that OC2 activation promotes a range of drug resistance mechanisms associated with treatment-emergent lineage variation in PC. Our findings support enhanced efforts to therapeutically target this protein as a means of suppressing treatment-resistant disease.

The homeodomain drives favorable DNA binding energetics of prostate cancer target ONECUT2

The ONECUT transcription factors feature a CUT and a homeodomain, evolutionarily conserved elements that bind DNA cooperatively, but the process remains mechanistically enigmatic. Using an integrative DNA binding analysis of ONECUT2, a driver of aggressive prostate cancer, we show that the homeodomain energetically stabilizes the ONECUT2-DNA complex through allosteric modulation of CUT. Further, evolutionarily conserved base-interactions in both the CUT and homeodomain are necessary for the favorable thermodynamics. We have identified a novel arginine pair unique to the ONECUT family homeodomain that can adapt to DNA sequence variations. Base interactions in general, including by this arginine pair, are critical for optimal DNA binding and transcription in a prostate cancer model. These findings provide fundamental insights into DNA binding by CUT-homeodomain proteins with potential therapeutic implications.

One-Sentence Summary

Base-specific interactions regulate homeodomain-mediated stabilization of DNA binding by the ONECUT2 transcription factor.

Stimulation of antitumor immunity by FoxP3-targeting PROTAC

CD4 + regulatory T cells (Tregs) play a central role in regulating and suppressing anti-tumor immune responses. FoxP3 is a transcription factor and master regulator of the Treg lineage. We developed and characterized a proteolysis targeting chimeric (PROTAC) drug that targets FoxP3 (PF). PF was created by linking the FoxP3 binding peptide P60 to pomalidomide, a ligand for E3 ligase. Ternary complex formation between PF, FoxP3, and cereblon (component of an E3 ligase) was confirmed using surface plasmon resonance assay (cooperativity factor of 2.27). PF decreased mouse and human FoxP3 expression in vitro in a proteasome-dependent manner. In mice, PF decreased FoxP3 in both the spleen and peripheral lymphocytes. PF-treated lymphocytes (human or mice) were better at stimulating CD8 + lymphocyte proliferation and activation. PF treatment decreased RENCA tumor growth in mice. PF enhanced antitumor immunity associated with αPD1 or mTOR inhibitor (mTORi). Lymphocytes from mice treated with PF and mTORi showed reduced metastatic tumor growth in untreated mice, providing further evidence for an adaptive immune response as the mechanism of action. We showed that PF binds FoxP3 and decreases FoxP3 expression in Tregs, reducing Treg function and generating antitumor immunity.

Glioma immunotherapy enhancement and CD8-specific sialic acid cleavage by isocitrate dehydrogenase (IDH)-1

The promise of adaptive cancer immunotherapy in treating highly malignant tumors such as glioblastoma multiforme (GBM) can only be realized through expanding its benefits to more patients. Alleviating various modes of immune suppression has so far failed to achieve such expansion, but exploiting endogenous immune enhancers among mutated cancer genes could represent a more direct approach to immunotherapy improvement. We found that Isocitrate Dehydrogenase-1 (IDH1), which is commonly mutated in gliomas, enhances glioma vaccine efficacy in mice and discerns long from short survivors after vaccine therapy in GBM patients. Extracellular IDH1 directly enhanced T cell responses to multiple tumor antigens, and prolonged experimental glioma cell lysis. Moreover, IDH1 specifically bound to and exhibited sialidase activity against CD8. By contrast, mutant IDH1R132H lacked sialidase activity, delayed killing in glioma cells, and decreased host survival after immunotherapy. Overall, our findings identify IDH1 as an immunotherapeutic enhancer that mediates the known T cell-enhancing reaction of CD8 desialylation. This uncovers a new axis for immunotherapeutic improvement in GBM and other cancers, reveals novel physiological and molecular functions of IDH1, and hints at an unexpectedly direct link between lytic T cell function and metabolic activity in target cells.

Dual kinase inhibitor for EGFR mutants and ErbB2 limit breast cancer

Mutations in the epidermal growth factor receptor (EGFR) have been found in more than 10% of non-small cell lung cancer (NSCLC) patients in North America. The vast majority of these differences are L858R point mutations in Exon 21. Currently, monoclonal antibodies directed against the extracellular domain of EGFR or small molecule/tyrosine kinase inhibitors (TKI) are the stalwarts of NSCLC therapy. Resistance, however, gradually develops because of the T790 mutation towards first and second generation TKIs. The third generation TKI AZD9291 (Osimertinib) has a high affinity for both activating and the acquired resistant mutation (T790 M) in EGFR, with a low affinity towards wild-type EGFR. Recent research, however, suggests that the EGFR (C797S) mutation in the tyrosine kinase domain is a likely cause of resistance to AZD9291. Another significant transformation mechanism associated with this resistance is erbB2 amplification. Our laboratory has developed a small kinase inhibitor, ER121 (MW: ∼500), that inhibits the erbB2/HER2 tyrosine kinases in addition to the EGFR C797S mutations. We have identified a TKI, ER121 targeting the mutant EGFR(T790 M). Using in vitro and in vivo models, examined the efficacy of ER121 on mutant EGFR cell lines. This has enabled us to establish that ER121 is well tolerated when administered orally and produces significant inhibitory activity against human cancers generated by mutant EGFR and amplified ErbB2.

Harnessing Antibody Polyspecificity for Cancer Immunotherapy

Targeting the diverse glycan repertoire expressed on tumor cells is considered a viable therapeutic strategy to deal with tumor cell heterogeneity. Inherently polyspecific, natural, glycan-reactive antibodies are purported to be protective in thwarting infections and in cancer immunotherapy. Tumor-associated carbohydrate antigens (TACAs) are related to pathogen glycans, to which nascent or natural antibodies exist and IgM responses are elicited. To capture the polyspecific nature of anticarbohydrate responses, we have focused on the rational design of carbohydrate mimetic peptides (CMPs) cross-reactive with TACA reactive antibodies. In particular, we have focused on the development of CMPs that display reactivity to GD2 and Lewis Y (LeY) reactive monoclonal antibodies. They would serve as templates for pan-immunogens inducing biosimilar polyreactive antibodies. In the design, we relied on structural analyses of CMP's enhanced binding to the templates using molecular modeling. Glycan reactivity patterns of affinity CMP-purified human antibodies further refined specificity profiles in comparison with the immune response to the CMP in clinical trials. In this study, we further define the molecular characteristics for this mimicry by considering the polyspecificity of LeY and GD2 reactive antibodies binding to the lacto-ceramide core Galβ(1,4)Glcβ(1-1')Cer. Binding to this minimum building block can be capitalized on for cancer therapy and diagnostics and illustrates a new approach in designing cancer vaccines taking advantage of the latent polyspecificity of antibodies and the relevance of natural antibodies in antigen discovery and design.

Receptor-interacting protein kinase 2 (RIPK2) stabilizes c-Myc and is a therapeutic target in prostate cancer metastasis

Despite progress in prostate cancer (PC) therapeutics, distant metastasis remains a major cause of morbidity and mortality from PC. Thus, there is growing recognition that preventing or delaying PC metastasis holds great potential for substantially improving patient outcomes. Here we show receptor-interacting protein kinase 2 (RIPK2) is a clinically actionable target for inhibiting PC metastasis. RIPK2 is amplified/gained in ~65% of lethal metastatic castration-resistant PC. Its overexpression is associated with disease progression and poor prognosis, and its genetic knockout substantially reduces PC metastasis. Multi-level proteomics analyses reveal that RIPK2 strongly regulates the stability and activity of c-Myc (a driver of metastasis), largely via binding to and activating mitogen-activated protein kinase kinase 7 (MKK7), which we identify as a direct c-Myc-S62 kinase. RIPK2 inhibition by preclinical and clinical drugs inactivates the noncanonical RIPK2/MKK7/c-Myc pathway and effectively impairs PC metastatic outgrowth. These results support targeting RIPK2 signaling to extend metastasis-free and overall survival.

Co-Variation of Serum Osteoprotegerin and Pigment-Epithelial Derived Factor as Biomarker of Pancreatic Cancer

Pancreatic cancer is one the most lethal cancers. Currently, there are reliable predictive markers to assess cancer development. Widely used CA19-9 molecular marker has been less effective in the diagnosis of early stages of cancer.

OBJECTIVE

To study if the soluble Osteoprotegerin (OPG) and pigment-epithelial derived factor (PEDF) levels in serum will be an indicator of cancer progression.

METHODS

Soluble OPG and PEDF were measured from human pancreatic cancer patients by ELISA.

RESULTS

We show that while OPG has been less predictive features, PEDF is more sensitive than CA19-9 in cancer detection. More importantly, PEDF and CA19-9 as combined markers showed higher sensitivity in stratifying early stages of pancreatic cancer.

CONCLUSION

Results from the pilot studies suggest that PEDF is useful biomarker for pancreatic cancer.

Neuropilin 1 regulates bone marrow vascular regeneration and hematopoietic reconstitution

Ionizing radiation and chemotherapy deplete hematopoietic stem cells and damage the vascular niche wherein hematopoietic stem cells reside. Hematopoietic stem cell regeneration requires signaling from an intact bone marrow (BM) vascular niche, but the mechanisms that control BM vascular niche regeneration are poorly understood. We report that BM vascular endothelial cells secrete semaphorin 3 A (SEMA3A) in response to myeloablation and SEMA3A induces p53 - mediated apoptosis in BM endothelial cells via signaling through its receptor, Neuropilin 1 (NRP1), and activation of cyclin dependent kinase 5. Endothelial cell - specific deletion of Nrp1 or Sema3a or administration of anti-NRP1 antibody suppresses BM endothelial cell apoptosis, accelerates BM vascular regeneration and concordantly drives hematopoietic reconstitution in irradiated mice. In response to NRP1 inhibition, BM endothelial cells increase expression and secretion of the Wnt signal amplifying protein, R spondin 2. Systemic administration of anti - R spondin 2 blocks HSC regeneration and hematopoietic reconstitution which otherwise occurrs in response to NRP1 inhibition. SEMA3A - NRP1 signaling promotes BM vascular regression following myelosuppression and therapeutic blockade of SEMA3A - NRP1 signaling in BM endothelial cells accelerates vascular and hematopoietic regeneration in vivo.

Challenges in Detection of Serum Oncoprotein: Relevance to Breast Cancer Diagnostics

Breast cancer is a highly prevalent malignancy that shows improved outcomes with earlier diagnosis. Current screening and monitoring methods have improved survival rates, but the limitations of these approaches have led to the investigation of biomarker evaluation to improve early diagnosis and treatment monitoring. The enzyme-linked immunosorbent assay (ELISA) is a specific and robust technique ideally suited for the quantification of protein biomarkers from blood or its constituents. The continued clinical relevancy of this assay format will require overcoming specific technical challenges, including the ultra-sensitive detection of trace biomarkers and the circumventing of potential assay interference due to the expanding use of monoclonal antibody (mAb) therapeutics. Approaches to increasing the sensitivity of ELISA have been numerous and include employing more sensitive substrates, combining ELISA with the polymerase chain reaction (PCR), and incorporating nanoparticles as shuttles for detection antibodies and enzymes. These modifications have resulted in substantial boosts in the ability to detect extremely low levels of protein biomarkers, with some systems reliably detecting antigen at sub-femtomolar concentrations. Extensive utilization of mAb therapies in oncology has presented an additional contemporary challenge for ELISA, particularly when both therapeutic and assay antibodies target the same protein antigen. Resolution of issues such as epitope overlap and steric hindrance requires a rational approach to the design of diagnostic antibodies that takes advantage of modern antibody generation pipelines, epitope binning techniques and computational methods to strategically target biomarker epitopes. This review discusses technical strategies in ELISA implemented to date and their feasibility to address current constraints on sensitivity and problems with interference in the clinical setting. The impact of these recent advancements will depend upon their transformation from research laboratory protocols into facile, reliable detection systems that can ideally be replicated in point-of-care devices to maximize utilization and transform both the diagnostic and therapeutic monitoring landscape.

Rational Design of Constrained Peptides as Protein Interface Inhibitors

The lack of progress in developing targeted therapeutics directed at protein–protein complexes has been due to the absence of well-defined ligand-binding pockets and the extensive intermolecular contacts at the protein–protein interface. Our laboratory has developed approaches to dissect protein–protein complexes focusing on the superfamilies of erbB and tumor necrosis factor (TNF) receptors by the combined use of structural biology and computational biology to facilitate small molecule development. We present a perspective on the development and application of peptide inhibitors as well as immunoadhesins to cell surface receptors performed in our laboratory.

The Effects of Receptor Activator of NF-κB Ligand-Binding Peptides on Bone Resorption and Bone Formation

Receptor activator of NF-κB ligand (RANKL)-binding peptides inhibit bone resorption and were recently shown to activate bone formation. The stimulatory mechanism underlying bone formation associated with these peptides was explained as RANKL-reverse signaling, wherein RANKL molecules on osteoblasts work as receptors to stimulate osteoblast differentiation. However, why RANKL-binding peptides stimulate osteoblast differentiation while osteoprotegerin (OPG), which is well known to bind to RANKL, cannot activate osteoblast differentiation has remained unclear. In this mini-review, we introduce three main issues: (1) The inhibitory effects of two RANKL-binding peptides (W9 and OP3-4) on bone resorption; (2) The stimulatory effects of the RANKL-binding peptides on osteoblast differentiation; and (3) The accumulation and membrane clustering of RANKL molecules at the cell surface of osteoblasts as a potential molecular switch stimulating osteoblast differentiation by RANKL-binding peptides.

Disabling the Nuclear Translocalization of RelA/NF-κB by a Small Molecule Inhibits Triple-Negative Breast Cancer Growth

INTRODUCTION

Constitutive activation of NF-κB has been implicated as being contributive to cancer cell growth, drug resistance, and tumor recurrence in many cancers including breast cancer. Activation of NF-κB leads to nuclear translocation of RelA, a critical component of the NF-κB transcription factor complex, which subsequently binds to specific DNA sites and activates a multitude of genes involved in diverse cell functions. Studies show that triple-negative breast cancer (TNBC) cells possess constitutively active NF-κB and concomitantly have higher levels of nuclear localization of RelA than cytoplasmic RelA. This feature is considered to be associated with the response to chemotherapy. However, currently, there is no specific inhibitor to block nuclear translocation of RelA.

METHODS

A structure-based approach was used to develop a small-molecule inhibitor of RelA nuclear translocation. The interaction between this molecule and RelA was verified biophysically through isothermal titration calorimetry and microscale thermophoresis. TNBC cell lines MDA-MB-231 and MDA-MB-468 and a human TNBC xenograft model were used to verify in vitro and in vivo efficacy of the small molecule, respectively.

RESULTS

We found that the small molecule, CRL1101, bound specifically to RelA as indicated by the biophysical assays. Further, CRL1101 blocked RelA nuclear translocation in breast cancer cells in vitro, and markedly reduced breast tumor growth in a triple-negative breast cancer xenograft model.

CONCLUSION

Our study demonstrates that CRL1101 may lead to new NF-κB-targeted therapeutics for TNBC. Further, blocking of nuclear translocation of shuttling transcription factors may be a useful general strategy in cancer drug development.

Elevated Asparagine Biosynthesis Drives Brain Tumor Stem Cell Metabolic Plasticity and Resistance to Oxidative Stress

Asparagine synthetase (ASNS) is a gene on the long arm of chromosome 7 that is copy-number amplified in the majority of glioblastomas. ASNS copy-number amplification is associated with a significantly decreased survival. Using patient-derived glioma stem cells (GSC), we showed that significant metabolic alterations occur in gliomas when perturbing the expression of ASNS, which is not merely restricted to amino acid homeostasis. ASNS-high GSCs maintained a slower basal metabolic profile yet readily shifted to a greatly increased capacity for glycolysis and oxidative phosphorylation when needed. This led ASNS-high cells to a greater ability to proliferate and spread into brain tissue. Finally, we demonstrate that these changes confer resistance to cellular stress, notably oxidative stress, through adaptive redox homeostasis that led to radiotherapy resistance. Furthermore, ASNS overexpression led to modifications of the one-carbon metabolism to promote a more antioxidant tumor environment revealing a metabolic vulnerability that may be therapeutically exploited. IMPLICATIONS: This study reveals a new role for ASNS in metabolic control and redox homeostasis in glioma stem cells and proposes a new treatment strategy that attempts to exploit one vulnerable metabolic node within the larger multilayered tumor network.

Perspective on Crystallographic Studies of Antibody Structures

In the past 50 years, there has been a great progress made in understanding and deploying antibodies in biology, medicine, and therapy. In this study, a brief overview is presented on how the crystal structures of antibody fragments guided therapeutic strategies emanating from our laboratories along with some historical perspective.

Impact of oral diseases on daily activities among 12- to 15-year-old institutionalized orphan and non-orphan children in Bengaluru city: A cross-sectional analytical study

Background and Objective

As parents are the primary decision-makers of child's health, a study was conducted to assess and compare the oral health status and impact of oral diseases on daily activities among 12- to 15-year-old institutionalized orphan and non-orphan children in Bengaluru city.

Materials and Methods

This cross-sectional analytical study was conducted among 210 orphans and 210 government school children living with parents. Data with regard to the impact of oral diseases on daily activities were collected by means of Child Oral Impacts on Daily Performances (C-OIDP) index, and oral health status was determined using WHO Oral Health Assessment Form 1997.

Statistical Analysis

Descriptive statistics of the key variables were reported and data were analyzed using Pearson's Chi-square test, Mann-Whitney U-test, One-way analysis of variance and Step-wise multiple linear regression analysis. Statistical significance was set at P < 0.05 for this study.

Results

Common oral health problems perceived by orphans and non-orphans were bleeding gums (16.8% and 12.4%) and toothache (12.7% and 13.7%), respectively. The daily performances most affected were cleaning mouth (33.3%; orphans 5.35 ± 4.22; non-orphans 7.05 ± 7.55; P = 0.000) and eating (33.1%; orphans 6.91 ± 6.09; non-orphans 7.07 ± 6.78; P = 0.003). Oral mucosal condition, dental fluorosis, dentofacial anomalies, and calculus showed significant difference among orphans and non-orphans (P = 0.000).

Conclusion

C-OIDP score was high in orphans. Age, dental fluorosis, and decayed teeth were the significant factors for determining C-OIDP score. More than half of the study subjects were suffering from oral diseases which required treatment to improve their quality of life.

Dual targeting of GSK3B and HDACs reduces tumor growth and improves survival in an ovarian cancer mouse model

Objective.

To investigate the anti-tumor effect of a newly-developed dual inhibitor (APCS-540) of glycogen synthase kinase 3 beta (GSK3B) and histone deacetylases (HDACs) in ovarian cancer cells.

Methods.

The effects of APCS-540 on cancer cell proliferation, migration, invasion and cancer stemness were investigated in vitro in human (KURAMOCHI, OVCA420, OVSAHO) and mouse (BR-Luc, ID8, MOSE-HRas-Myc) ovarian cancer cells. Cisplatin-sensitive (A2780) and cisplatin-resistant (A2780cis) cell lines were used to evaluate APCS-540’s effect on chemoresistance. The immunocompetent syngeneic mouse model BR-Luc was used to test the effect of APCS-540 on ovarian cancer progression and survival.

Results.

APCS-540 showed significant anti-tumor effects in vitro in both human and mouse ovarian cancer cells. Importantly, APCS-540 demonstrated marked cytotoxicity against cisplatin-resistant cancer cells and reversed cisplatin-resistance when used in combination with platinum. APCS-540 significantly decreased cancer cell invasion. A significant 66% increase in survival was observed in mice treated with APCS-540 compared to control mice.

Conclusion.

Dual inhibition of GSK3B and HDACs via APCS-540 showed potent anti-tumor activity in vitro and in vivo, suggesting that APCS-540 may provide a novel treatment option for ovarian cancer, including the platinum-resistant disease.

Impact of Health Education Intervention on Breast Cancer Awareness among Rural Women of Tamil Nadu

Background:

The most common cancer among Indian females is breast cancer. Limited access to early detection and treatment is responsible for more than half of the deaths, primarily in rural areas, where organized mammography screening is neither affordable nor feasible. Therefore, imparting awareness on breast health and breast self-examination (BSE) is highly recommended. This study aimed to assess the impact of a health education interventional program on breast health awareness and BSE among rural women of Tamil Nadu.

Methodology:

A quasi-experimental study was conducted among 266 women. A preinterventional survey was done using a pretested validated questionnaire. A multipronged breast health education intervention was administered and its effectiveness was measured after 3 months using the same tool.

Results:

There was a statistically significant (P = 0.0001) improvement in the knowledge of breast health, perceived susceptibility, and reasons for practice and proficiency of BSE practice of the interventional group from pre- to post-test. After the interventional program, 71.8% of increase in knowledge about breast health and BSE was observed. In addition, 64.7% of the women practiced BSE compared to 7.14% pretest.

Conclusion:

This study highlights the awareness needs by the women and application of extensive strategies to increase the acceptance of cancer screening programs.

c-Rel Is a Myeloid Checkpoint for Cancer Immunotherapy

Immunotherapy that targets lymphoid cell checkpoints holds great promise for curing cancer. However, a majority of cancer patients do not respond to this form of therapy. In addition to lymphoid cells, myeloid cells play essential roles in controlling immunity to cancer. Whether myeloid checkpoints exist that can be targeted to treat cancer is not well established. Here we show that c-Rel, a member of the nuclear factor (NF)-B family, specified the generation of myeloid-derived suppressor cells (MDSCs) by selectively turning on pro-tumoral genes while switching off anti-tumoral genes through a c-Rel enhanceosome. c-Rel deficiency in myeloid cells markedly inhibited cancer growth in mice, and pharmaceutical inhibition of c-Rel had the same effect. Combination therapy that blocked both c-Rel and the lymphoid checkpoint protein PD1 was more effective in treating cancer than blocking either alone. Thus, c-Rel is a myeloid checkpoint that can be targeted for treating cancer.

iPSC modeling of young-onset Parkinson's disease reveals a molecular signature of disease and novel therapeutic candidates

Young-onset Parkinson's disease (YOPD), defined by onset at <50 years, accounts for approximately 10% of all Parkinson's disease cases and, while some cases are associated with known genetic mutations, most are not. Here induced pluripotent stem cells were generated from control individuals and from patients with YOPD with no known mutations. Following differentiation into cultures containing dopamine neurons, induced pluripotent stem cells from patients with YOPD showed increased accumulation of soluble α-synuclein protein and phosphorylated protein kinase Cα, as well as reduced abundance of lysosomal membrane proteins such as LAMP1. Testing activators of lysosomal function showed that specific phorbol esters, such as PEP005, reduced α-synuclein and phosphorylated protein kinase Cα levels while increasing LAMP1 abundance. Interestingly, the reduction in α-synuclein occurred through proteasomal degradation. PEP005 delivery to mouse striatum also decreased α-synuclein production in vivo. Induced pluripotent stem cell-derived dopaminergic cultures reveal a signature in patients with YOPD who have no known Parkinson's disease-related mutations, suggesting that there might be other genetic contributions to this disorder. This signature was normalized by specific phorbol esters, making them promising therapeutic candidates.

EC359: A First-in-Class Small-Molecule Inhibitor for Targeting Oncogenic LIFR Signaling in Triple-Negative Breast Cancer

Leukemia inhibitory factor receptor (LIFR) and its ligand LIF play a critical role in cancer progression, metastasis, stem cell maintenance, and therapy resistance. Here, we describe a rationally designed first-in-class inhibitor of LIFR, EC359, which directly interacts with LIFR to effectively block LIF/LIFR interactions. EC359 treatment exhibits antiproliferative effects, reduces invasiveness and stemness, and promotes apoptosis in triple-negative breast cancer (TNBC) cell lines. The activity of EC359 is dependent on LIF and LIFR expression, and treatment with EC359 attenuated the activation of LIF/LIFR-driven pathways, including STAT3, mTOR, and AKT. Concomitantly, EC359 was also effective in blocking signaling by other LIFR ligands (CTF1, CNTF, and OSM) that interact at LIF/LIFR interface. EC359 significantly reduced tumor progression in TNBC xenografts and patient-derived xenografts (PDX), and reduced proliferation in patient-derived primary TNBC explants. EC359 exhibits distinct pharmacologic advantages, including oral bioavailability, and in vivo stability. Collectively, these data support EC359 as a novel targeted therapeutic that inhibits LIFR oncogenic signaling.See related commentary by Shi et al., p. 1337.

Abstract P2-06-02: Development of a first-in-class small molecule inhibitor (EC359) targeting oncogenic LIF/LIFR signaling for the treatment of triple negative breast cancer

Background: Leukemia inhibitory factor (LIF) and its receptor LIFR are over-expressed in multiple solid tumors and play a key role in tumor growth, progression, and resistance to standard anti-cancer treatments. Triple-negative breast cancer (TNBC) lacks targeted therapies and represents a disproportional share of breast cancer (BCa) mortality. TNBC exhibits autocrine stimulation of the LIF/LIFR axis and overexpression of LIF is associated with poorer relapse-free survival in BCa patients. LIF signaling also promotes maintenance of stem cells. Therefore, targeting the LIF/LIFR axis may have therapeutic utility in TNBC.

Methods: We rationally designed a small organic molecule (EC359) that emulates the LIF/LIFR binding site and functions as a LIFR inhibitor from a library of compounds. In silico docking studies were used to identify the putative interaction of the EC359 and LIF/LIFR complex. Direct binding of EC359 to LIFR was confirmed using surface plasmon resonance (SPR) and microscale thermophoresis technique (MST) assays. In vitro activity was tested using Cell-Titer Glo, MTT, invasion, and apoptosis assays. Mechanistic studies were conducted using Western blot, reporter gene assays, and RNA-seq analysis. Xenograft, patient-derived xenograft (PDX), and patient-derived explant (PDEX) models were used for preclinical evaluation and toxicity.

Results: Molecular docking studies showed that EC359 interacts at the LIF/LIFR binding interface. SPR and MST studies confirmed direct interaction of EC359 to LIFR. EC359 reduced the growth of TNBC cells with high potency (IC50 50-100nM) and promoted apoptosis. Further, EC359 treatment reduced invasion and stemness of TNBC cells. EC359 activity is dependent on the expression levels of LIFR and showed little or no activity on TNBC cells that have low levels of LIFR or ER+ve BCa cells. Further, EC359 significantly reduced the viability of cisplatin and taxane-resistant TNBC cells and enhanced the efficacy of HDAC inhibitors. Mechanistic and biochemical studies showed that EC359 interacts with LIFR and effectively blocking LIF/LIFR interactions. EC359 also blocked LIFR interactions with other LIFR ligands such as oncostatin M, ciliary neurotrophic factor, and cardiotrophin-1. EC359 treatment attenuated the activation of LIF/LIFR driven pathways including STAT3, mTOR, AKT, and MAPK. RNA-seq analysis identified regulation of apoptosis as one of the important pathway modulated by EC359. In TNBC xenograft and PDX assays, EC359 significantly reduced tumor progression. Further, using human primary BCa PDEX cultures, we demonstrated that EC359 has the potential to substantially reduce the proliferation of human BCa. Pharmacologically, EC359 exhibited high oral bioavailability and long half-life with a wide therapeutic window.

Conclusions: EC359 is a novel targeted therapeutic agent that inhibits LIF/LIFR oncogenic signaling in TNBC via a unique mechanism of action. EC359 has the distinct pharmacologic advantages of oral bioavailability, in vivo stability, and is associated with minimal systemic side effects. (DOD BCRP grant #BC170312)

Citation Format: Viswanadhapalli S, Luo Y, Sareddy GR, Santhamma B, Zhou M, Li M, Pratap UP, Altwegg KA, Li X, Srinivasan U, Ma S, Chang A, Riveros AC, Zhang KY, Dileep KV, Pan X, Murali R, Bajda M, Raj G, Brenner A, Manthati V, Rao M, Tekmal RR, Nair HB, Nickisch KJ, Vadlamudi RK. Development of a first-in-class small molecule inhibitor (EC359) targeting oncogenic LIF/LIFR signaling for the treatment of triple negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-06-02.

The induction of RANKL molecule clustering could stimulate early osteoblast differentiation

We recently found that the membrane-bound receptor activator of NF-κB ligand (RANKL) on osteoblasts works as a receptor to stimulate osteoblast differentiation, however, the reason why the RANKL-binding molecules stimulate osteoblast differentiation has not been well clarified. Since the induction of cell-surface receptor clustering is known to lead to cell activation, we hypothesized that the induction of membrane-RANKL clustering on osteoblasts might stimulate osteoblast differentiation. Immunoblotting showed that the amount of RANKL on the membrane was increased by the RANKL-binding peptide OP3-4, but not by osteoprotegerin (OPG), the other RANKL-binding molecule, in Gfp-Rankl-transfected ST2 cells. Observation under a high-speed atomic force microscope (HS-AFM) revealed that RANKL molecules have the ability to form clusters. The induction of membrane-RANKL-OPG-Fc complex clustering by the addition of IgM in Gfp-Rankl-transfected ST2 cells could enhance the expression of early markers of osteoblast differentiation to the same extent as OP3-4, while OPG-Fc alone could not. These results suggest that the clustering-formation of membrane-RANKL on osteoblasts could stimulate early osteoblast differentiation.

An Inhibitor of GSK3B and HDACs Kills Pancreatic Cancer Cells and Slows Pancreatic Tumor Growth and Metastasis in Mice

BACKGROUND & AIMS

Growth, progression, and drug resistance of pancreatic ductal adenocarcinomas (PDACs) have been associated with increased levels and activity of glycogen synthase kinase 3 beta (GSK3B) and histone deacetylases (HDACs). We designed and synthesized molecules that simultaneously inhibit the activities of both enzymes. We tested the effects of one of these molecules, Metavert, in pancreatic cancer cells and mice with pancreatic tumors.

METHODS

We tested the ability of Metavert to bind GSK3B and HDACs using surface plasmon resonance. MIA PaCa-2, Bx-PC3, HPAF-II, and HPDE6 cell lines were incubated with different concentrations of Metavert, with or without paclitaxel or gemcitabine, or with other inhibitors of GSK3B and HDACs; cells were analyzed for apoptosis and migration and by immunoblotting, immunofluorescence, and real-time polymerase chain reaction. Krasþ/LSLG12D;Trp53þ/LSLR172H;Pdx-1-Cre (KPC) mice (2 months old) were given injections of Metavert (5 mg/kg, 3 times/week) or vehicle (control). B6.129J mice with tumors grown from UN-KPC961-Luc cells were given injections of Metavert or vehicle. Tumors and metastases were counted and pancreata were analyzed by immunohistochemistry. Glucose metabolism was measured using 13C-glucose tracer and mass spectroscopy and flow cytometry. Cytokine levels in blood samples were measured using multiplexing enzyme-linked immunosorbent assay.

RESULTS

Metavert significantly reduced survival of PDAC cells but not nontransformed cells; the agent reduced markers of the epithelial-to-mesenchymal transition and stem cells in PDAC cell lines. Cells incubated with Metavert in combination with irradiation and paclitaxel or gemcitabine had reduced survival compared with cells incubated with either agent alone; Metavert increased killing of drug-resistant PDAC cells by paclitaxel and gemcitabine. PDAC cells incubated with Metavert acquired normalized glucose metabolism. Administration of Metavert (alone or in combination with gemcitibine) to KPC mice or mice with syngeneic tumors significantly increased their survival times, slowed tumor growth, prevented tumor metastasis, decreased tumor infiltration by tumor-associated macrophages, and decreased blood levels of cytokines.

CONCLUSIONS

In studies of PDAC cells and 2 mouse models of PDAC, we found a dual inhibitor of GSK3B and HDACs (Metavert) to induce cancer cell apoptosis, reduce migration and expression of stem cell markers, and slow growth of tumors and metastases. Metavert had synergistic effects with gemcitabine.

Baicalein Targets GTPase-Mediated Autophagy to Eliminate Liver Tumor-Initiating Stem Cell-Like Cells Resistant to mTORC1 Inhibition

Drug resistance is a major problem in the treatment of liver cancer. Mammalian Target of Rapamycin 1 (mTORC1) inhibitors have been tested for the treatment of liver cancer based on hyperactive mTOR in this malignancy. However, their clinical trials showed poor outcome, most likely due to their ability to upregulate CD133 and promote chemoresistance. The CD133⁺ tumor-initiating stem cell-like cells (TICs) isolated from mouse and human liver tumors are chemoresistant, and identification of an approach to abrogate this resistance is desired. In search of a compound that rescinds resistance of TICs to mTORC1 inhibition and improves chemotherapy, we identified baicalein (BC), which selectively chemosensitizes TICs and the human hepatocellular carcinoma (HCC) cell line Huh7 cells but not mouse and human primary hepatocytes. Nanobead pull-down and mass-spectrometric analysis, biochemical binding assay, and three-dimensional computational modeling studies reveal BC's ability to competitively inhibit guanosine triphosphate binding of SAR1B guanosine triphosphatase, which is essential for autophagy. Indeed, BC suppresses autophagy induced by an mTORC1 inhibitor and synergizes cell death caused by mTORC1 inhibition in TIC and Huh7 spheroid formation and in the patient-derived xenograft model of HCC. The BC-induced chemosensitization is rescued by SAR1B expression and phenocopied by SAR1B knockdown in cancer cells treated with a mTORC1 inhibitor. Conclusion: These results identify SAR1B as a target in liver TICs and HCC cells resistant to mTORC1 inhibition.

Abstract A047: ONECUT2 is a targetable master regulator of aggressive variants of castration-resistant prostate cancer

Background: Treatment of prostate cancer by hormone suppression leads to the appearance of aggressive variants of metastatic castration-resistant prostate cancer (mCRPC) with variable or no dependence on the androgen receptor (AR). Here we identify the neural transcription factor ONECUT2 as a negative regulator of the AR axis, that emerges in aggressive PC variants to control transcriptional networks linked to CRPC and neuroendocrine (NE) differentiation. We further demonstrate that ONECUT2 can be targeted with a small molecule that inhibits mCRPC metastasis in mice.

Methods: ONECUT2 was confirmed as a mCRPC-relevant protein and to be targetable by computational modeling and bioinformatics, enforced expression, silencing, microarray, ChIP-Seq, immunohistochemistry, immunofluorescence, quantitative imaging, functional assays, in vivo experiments, and surface plasmon resonance.

Results: We have performed a master regulator analysis using 260 mCRPC transcriptome profiles and developed a model transcription factor network for mCRPC that associates ONECUT2 for the first time with metastatic progression. Gene expression profiling of ONECUT2-engineered PC cell lines has allowed us to generate a ONECUT2 activity signature that reveals high positive correlation with pro-neural and aggressive PC signatures, and a negative correlation with AR activation pathways. We find that ONECUT2 is a negative regulator of AR expression and a repressor of its transcriptional program through direct binding to AR target genes. We also find that ONECUT2 is significantly increased in human NEPC and confers NE properties to CRPC through direct downregulation of the NEPC inhibitor FOXA1 and direct upregulation of the NEPC driver PEG10. Finally, we show that ONECUT2 is required for cell growth and survival and that it can be targeted with a small molecule that, by binding to the ONECUT2 C-terminal DNA binding domain, inhibits mCRPC metastasis in mice.

Conclusions: OC2 is a master regulator of aggressive mCRPC variants that drives AR-dependent adenocarcinoma toward NEPC differentiation by blocking AR/FOXA1-activity and inducing PEG10. OC2 can be targeted with a drug-like small molecule that inhibits CRPC metastasis in mice. Patients with OC2 active tumors may benefit from OC2 inhibitor therapy.

Citation Format: Mirja Rotinen, Sungyong You, Julie Yang, Simon Coetzee, Wen-Chin Huang, Fangjin Huang, Xinlei Pan, Alberto Yáñez, Dennis Hazelett, Chia-Yi Chu, Leland Chung, Stephen Freedland, Dolores Di Vizio, Isla Garraway, Ramachandran Murali, Beatrice Knudsen, Michael Freeman. ONECUT2 is a targetable master regulator of aggressive variants of castration-resistant prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A047.

Nuclear receptor/Wnt beta-catenin interactions are regulated via differential CBP/p300 coactivator usage

Over 400 million years ago, the evolution of vertebrates gave rise to a life cycle in which the organism began to live longer particularly as an adult. To accommodate such a longer lifespan, the organism underwent adaptation, developing a mechanism for long-lived cellular homeostasis. This adaptation required a population of long-lived relatively quiescent somatic stem cells (SSCs) along with a more proliferative differentiated daughter cell population, and was necessary to safeguard the genetic attributes with which SSCs were endowed. Intriguingly, cAMP response element binding protein (CREB)-binding protein (CBP) and E1A-binding protein, 300 kDa (p300), the highly homologous Kat3 coactivators had diverged, through duplication of ancestral Kat3, immediately preceding the evolution of vertebrates, given that both CBP and p300 have been detected in nearly all vertebrates versus non-vertebrates. We now demonstrate that a relatively small, highly evolutionarily conserved, amino terminal 9 amino acid deletion in CBP versus p300, plays a critical role in allowing for both robust maintenance of genomic integrity in stem cells and the initiation of a feed-forward differentiation mechanism by tightly controlling the interaction of the nuclear receptor family with the Wnt signaling cascade in either an antagonistic or synergistic manner.

Abstract 5875: Development of LIFR inhibitor EC359 as a novel therapeutic for ovarian cancer

Background: Ovarian cancer (OCa) is the deadliest of all gynecologic cancers. OCa patients initially respond to standard combinations of surgical and cytotoxic therapy; however, ~80% will develop recurrence and inevitably succumb to chemotherapy-resistant disease. OCa stem cells are implicated in the tumor initiation and therapy resistance. LIFR signaling plays a critical role in OCa progression and stemness. Further, high circulating LIF levels correlate with tumor recurrence and chemoresistance. The autocrine loop involving LIF, LIFR and STAT3 axis drives sustained fibroblast production of inflammatory mediators. This represents a significant problem and a critical need exists for development of novel therapies targeting the LIFR axis for treating OCa.

Methods: We have rationally designed and synthesized a small organic molecule (EC359) that emulates the LIF-LIFR binding site and functions as a LIFR inhibitor from a library of compounds. In silico docking studies were used to identify the putative interaction of the EC359 and LIF/LIFR complex. Binding of EC359 to LIFR was confirmed using surface plasmon resonance (SPR) and IP assays. Mechanistic studies were conducted using Western, RT-qPCR, and RNA-Seq analysis. Xenograft models were used for preclinical evaluation and toxicity. The efficacy of EC359 was tested using Patient-Derived eXplants (PDeX).

Results: Global analysis of online databases revealed negative correlation of OCa survival with LIFR expression. Molecular docking studies showed EC359 interacts at the LIF-LIFR binding interface. SPR studies confirmed interaction of EC359 to LIFR. Western analysis of eight cells that represent four subtypes of OCa confirmed higher expression of LIF and LIFR. EC359 reduced the growth of eight OCa cells with high potency (IC50 10-50 nM) and promoted apoptosis. EC359 treatment reduced stemness of OCa cells. EC359 activity is dependent on the level of expression of LIFR with little activity on cells that do not express LIFR. EC359 significantly reduced the viability of carboplatin- and taxol-resistant OCa cells. Mechanistic studies showed EC359 interacts with LIFR and block its interaction with LIF. EC359 treatment reduced the STAT3 phosphorylation, mTOR and downstream survival signaling cascades. RNA sequencing revealed unique pathways blocked by EC359. Treatment of xenograft tumors with EC359 significantly reduced the tumor volume compared to control. Further, using PDeX of OCa, we demonstrated that EC359 has potential to reduce the proliferation. Pharmacologically, EC359 exhibited high oral bioavailability and long half-life with a wide therapeutic window.

Conclusions: EC359 is a novel agent that targets LIF-LIFR axis and has activity against chemotherapy-resistant and primary OCa tumors. EC359 has the distinct pharmacologic advantages of oral bioavailability, in vivo stability, and is associated with minimal systemic side effects.

Citation Format: Suryavathi Viswanadhapalli, Hareesh B Nair, Bindu Santhamma, Gangadhara R Sareddy, Yiliao Luo, Xinlei Pan, Edward R Kost, Ramachandran Murali, Rajeshwar Rao Tekmal, Klaus J Nickisch, Ratna K Vadlamudi. Development of LIFR inhibitor EC359 as a novel therapeutic for ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5875.

Structure of a Thyrotropin Receptor Monoclonal Antibody Variable Region Provides Insight into Potential Mechanisms for its Inverse Agonist Activity

BACKGROUND

The high constitutive, or ligand-independent, activity of the thyrotropin receptor (TSHR) is of clinical importance in some thyroid conditions, particularly well-differentiated thyroid carcinoma remnants following incomplete ablative therapy (surgery and radioiodine). Under these conditions, even total suppression of TSH by thyroid hormone administration does not fully reduce TSHR activity, a driver of thyrocyte growth.

METHODS

CS-17 is a murine monoclonal antibody that has inverse agonist activity in that it suppresses TSHR constitutive activity. This study crystallized the CS-17 Fab and determined its atomic structure at a resolution of 3.4 Å.

RESULTS

In silico docking of this structure to that of the TSHR extracellular domain was accomplished by targeting to TSHR residue tyrosine 195 (Y195) known to contribute to the CS-17 epitope. High affinity interaction between these two molecules, primarily by the CS-17 immunoglobulin heavy chain, was validated by energetic analysis (K_D of 8.7 × 10^-11 M), as well as by previously obtained data on a number of individual TSHR amino acids in three regions whose mutagenesis reduced CS-17 binding as detected by flow cytometry.

CONCLUSIONS

Structural insight at atomic resolution of a TSHR antibody with inverse agonist activity opens the way for the development of a molecule with therapeutic potential, particularly in thyroid carcinoma. For this purpose, CS-17 will require "humanization" by substitution of its constant region (Fc component). In addition, with its epitope defined, the CS-17 affinity can be increased further by mutagenesis of selected amino acids in its heavy- and light-chain complementarity determining regions.

Abstract 4331: Novel Wnt-SCD-LRP5/6 pathway linking liver fibrosis to cancer

Activated hepatic stellate cells (HSCs) are primarily responsible for the genesis of liver fibrosis which promotes liver tumor development. Stearoyl-CoA desaturase (SCD) which synthesizes monounsaturated fatty acid (MUFA such as oleic acid or palmitoleic acid), is implicated in metabolic syndrome, tumorigenesis and stemness. Indeed, we demonstrate SCD upregulation in both HSCs and liver tumor cells in patients. Further, SCD correlates with the advancing grade of HCC and mortality in patients. However, its causality in tumorigenesis and mesenchyme-tumor crosstalk, and underlying mechanisms, are unknown. The present study aimed to determine whether and how SCD promotes and links liver fibrosis and cancer. In both HSCs and liver tumor-initiating stem cell-like cells (TIC), we reveal that the Wnt effector β-catenin is a potent co-activator for SREBP-1-dependent Scd transcription as demonstrated by promoter-reporter assay and re-ChIP analysis. We also discover β-catenin which drives SCD expression is in turn stabilized by SCD-derived MUFA. To identify molecular targets of MUFA mediating this SCD-β-catenin positive loop, we performed MUFA-nano-beads pull-down assay with TIC lysate, ESI-MS based identification of MUFA interacting proteins, computational docking analysis, co-IP and ribonucleoprotein-IP. These analyses reveal that MUFA is essential for LRP5/6 expression: MUFA interferes Transportin-1 and Ran-1 interaction, resulting in suppressed nuclear import of the mRNA binding protein HuR, HuR cytoplasmic accumulation, and increased HuR binding to and stabilization of Wnt co-receptor Lrp5/6 mRNA. As such, genetic or pharmacologic SCD inhibition reduces cytosolic HuR, LRP5/6 expression, β-catenin stabilization, HSC activation and TIC self-renewal and attenuates liver fibrosis and tumorigenesis in mice. Moreover, conditional genetic ablation of Scd2 in HSCs not only abrogates HSC-mediated promotion of TIC-derived tumorigenesis in a xenograft mouse model but also inhibits DEN-induced liver tumor development in Col1a1-Cre; Scd2flox/flox mice (tumor volume reduced to 21.5 + 7.9 vs. 360.9 + 193 mm3 in Scd2flox/flox mice; tumor multiplicity decreased to 18 + 5.4 vs. 45 + 8.4 in Scd2flox/flox mice, both p&lt;0.05). Collectively, our findings support that a newly disclosed Wnt-SCD-LRP5/6 loop may serve as a novel therapeutic target for liver cancer and underlies a known crosstalk between liver mesenchyme and liver tumor development.

Citation Format: Keane Lai, Soo-Mi Kweon, Feng Chi, Edward Hwang, Raymond Wu, Yasuaki Kabe, Ramachandran Murali, Lopa Mishra, James Ntambi, Hidekazu Tsukamoto. Novel Wnt-SCD-LRP5/6 pathway linking liver fibrosis to cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4331. doi:10.1158/1538-7445.AM2017-4331

Direct Antimicrobial Activity of IFN-β

Type I IFNs are a cytokine family essential for antiviral defense. More recently, type I IFNs were shown to be important during bacterial infections. In this article, we show that, in addition to known cytokine functions, IFN-β is antimicrobial. Parts of the IFN-β molecular surface (especially helix 4) are cationic and amphipathic, both classic characteristics of antimicrobial peptides, and we observed that IFN-β can directly kill Staphylococcus aureus Further, a mutant S. aureus that is more sensitive to antimicrobial peptides was killed more efficiently by IFN-β than was the wild-type S. aureus, and immunoblotting showed that IFN-β interacts with the bacterial cell surface. To determine whether specific parts of IFN-β are antimicrobial, we synthesized IFN-β helix 4 and found that it is sufficient to permeate model prokaryotic membranes using synchrotron x-ray diffraction and that it is sufficient to kill S. aureus These results suggest that, in addition to its well-known signaling activity, IFN-β may be directly antimicrobial and be part of a growing family of cytokines and chemokines, called kinocidins, that also have antimicrobial properties.

Yes1 signaling mediates the resistance to Trastuzumab/Lap atinib in breast cancer

Background

Overexpression of human epidermal growth factor receptor 2 (HER2) is observed in approximately 15–23% of breast cancers and these cancers are classified as HER2-positive breast cancer. Trastuzumab is the first-line targeted therapeutic drug for HER2-positive breast cancer and has improved patient overall survival. However, acquired resistance to trastuzumab is still a critical issue in breast cancer treatment. We previously established a trastuzumab-resistant breast cancer cell line (named as BT-474-R) from a trastuzumab-sensitive HER2-amplified cell line BT-474. Lapatinib is also a molecular-targeted drug for HER2-positive breast cancer, which acquired the resistance to trastuzumab. Acquired resistance to lapatinib is also an issue to be conquered.

Methods

We established trastuzumab/lapatinib-dual resistant cell line (named as BT-474-RL2) by additionally treating BT-474-R with lapatinib. We analyzed the mechanisms of resistance to trastuzumab and lapatinib. Besides, we analyzed the effect of the detected resistance mechanism in HER2-positive breast cancer patients.

Results

Proto-oncogene tyrosine-protein kinase Yes1, which is one of the Src family members, was amplified, overexpressed and activated in BT-474-R and BT-474-RL2. Silencing of Yes1 by siRNA induced both BT-474-R and BT-474-RL2 to restore the sensitivity to trastuzumab and lapatinib. Pharmaceutical inhibition of Yes1 by the Src inhibitor dasatinib was also effective to restore the sensitivity to trastuzumab and lapatinib in the two resistant cell lines. Combination treatment with dasatinib and trastuzumab induced down-regulation of signaling molecules such as HER2 and Akt. Moreover, the combination treatments induced G1-phase cell-cycle arrest and apoptosis. Consistent with cell line data, high expression of Yes1 mRNA was correlated with worse prognosis in patients with HER2-positive breast cancer.

Conclusion

Yes1 plays an important role in acquired resistance to trastuzumab and lapatinib in HER2-positive breast cancer. Our data suggest that pharmacological inhibition of Yes1 may be an effective strategy to overcome resistance to trastuzumab and lapatinib.

Group B Streptococcus Evades Host Immunity by Degrading Hyaluronan

In response to tissue injury, hyaluronan (HA) polymers are cleaved by host hyaluronidases, generating small fragments that ligate Toll-like receptors (TLRs) to elicit inflammatory responses. Pathogenic bacteria such as group B Streptococcus (GBS) express and secrete hyaluronidases as a mechanism for tissue invasion, but it is not known how this activity relates to immune detection of HA. We found that bacterial hyaluronidases secreted by GBS and other Gram-positive pathogens degrade pro-inflammatory HA fragments to their component disaccharides. In addition, HA disaccharides block TLR2/4 signaling elicited by both host-derived HA fragments and other TLR2/4 ligands, including lipopolysaccharide. Application of GBS hyaluronidase or HA disaccharides reduced pulmonary pathology and pro-inflammatory cytokine levels in an acute lung injury model. We conclude that breakdown of host-generated pro-inflammatory HA fragments to disaccharides allows bacterial pathogens to evade immune detection and could be exploited as a strategy to treat inflammatory diseases.

HER2-positive breast cancer targeting and treatment by a peptide-conjugated mini nanodrug

HER2+ breast cancer is one of the most aggressive forms of breast cancer. The new polymalic acid-based mini nanodrug copolymers are synthesized and specifically characterized to inhibit growth of HER2+ breast cancer. These mini nanodrugs are highly effective and in the clinic may substitute for trastuzumab (the marketed therapeutic antibody) and antibody-targeted nanobioconjugates. Novel mini nanodrugs are designed to have slender shape and small size. HER2+ cells were recognized by the polymer-attached trastuzumab-mimetic 12-mer peptide. Synthesis of the nascent cell-transmembrane HER2/neu receptors by HER2+ cells was inhibited by antisense oligonucleotides that prevented cancer cell proliferation and significantly reduced tumor size by more than 15 times vs. untreated control or PBS-treated group. We emphasize that the shape and size of mini nanodrugs can enhance penetration of multiple bio-barriers to facilitate highly effective treatment. Replacement of trastuzumab by the mimetic peptide favors reduced production costs and technical efforts, and a negligible immune response.

The Potential Role of Solvation in Antibody Recognition of the Lewis Y Antigen

Solvents play an important role in protein folding, protein-protein associations, stability, and specificity of recognition as in the case of antibody-antigen interactions through hydrogen bonds. One of the underappreciated features of protein-associated waters is that it weakens inter- and intra-molecular interactions by modulating electrostatic interactions and influencing conformational changes. Such observations demonstrate the direct relationship between macroscopic solvent effects on protein-protein interactions and atom-scale solvent-protein interactions. Although crystallographic solvents do explain some aspects of solvent-mediated interactions, molecular simulation allows the study of the dynamic role of solvents. Thus, analysis of conformations from molecular simulations are employed to understand the role of solvent on the inherent polyspecificity of a Lewis Y reactive germline gene relative to its expanded hybridomas and a humanized anti-Lewis Y antibody. Our analysis reveals that solvent mediates critical contacts through charged residues to facilitate cross-reactivity to carbohydrate antigens, but also increases the flexibility of some anti-Lewis Y antibodies concomitant with mutations (amino acid substitutions) to the germline antibody. Such flexibility might better allow for recognition and binding of internal structures of extended carbohydrate structures on tumor cells.

Peptide drugs accelerate BMP-2-induced calvarial bone regeneration and stimulate osteoblast differentiation through mTORC1 signaling

Both W9 and OP3‐4 were known to bind the receptor activator of NF‐κB ligand (RANKL), inhibiting osteoclastogenesis. Recently, both peptides were shown to stimulate osteoblast differentiation; however, the mechanism underlying the activity of these peptides remains to be clarified. A primary osteoblast culture showed that rapamycin, an mTORC1 inhibitor, which was recently demonstrated to be an important serine/threonine kinase for bone formation, inhibited the peptide‐induced alkaline phosphatase activity. Furthermore, both peptides promoted the phosphorylation of Akt and S6K1, an upstream molecule of mTORC1 and the effector molecule of mTORC1, respectively. In the in vivo calvarial defect model, W9 and OP3‐4 accelerated BMP‐2‐induced bone formation to a similar extent, which was confirmed by histomorphometric analyses using fluorescence images of undecalcified sections. Our data suggest that these RANKL‐binding peptides could stimulate the mTORC1 activity, which might play a role in the acceleration of BMP‐2‐induced bone regeneration by the RANKL‐binding peptides.