Low-density Lipoprotein Receptor-related Protein Research Articles

PPARs (Peroxisome Proliferator-activated Receptors) and Their Agonists in Alzheimer's Disease.

Alzheimer's disease (AD) is a neurodegenerative disease leading to dementia because of complex phathomechanisms like amyloid β (Aβ) aggregation, tau aggregates, and neurofibrillary tangles. Peroxisome proliferator-activated receptor (PPAR) agonists have been reported recently with neuroprotective and anti-inflammatory properties. PPARs belong to the superfamily of nuclear hormone receptors and function as ligand-activated transcription factors. These have emerged as crucial players in the pathogenesis of AD. This review presented the potential of PPARs and their agonists in treating neurodegenerative diseases like AD. <P> </P> PPARs regulate the expression of specific genes vital for synaptic function and neurotransmitter release. PPAR agonists play a critical role in increasing the clearance of Aβ peptides by lowdensity lipoprotein receptor-related protein 1 (LRP1) in the microvascular endothelial cells of the human brain. Studies have shown that PPAR agonists reduce the level of APoE-mRNA, contributing to the accumulation of Aβ plaques and up-regulation of PPAR. A knockout of miR-128 has been found to inhibit AD-like cognitive decline, amyloid precursor protein (APP) amyloidogenic processing, and inflammatory responses in AD. <P> </P> PPARs are involved in the pathomechanism of AD, and therefore, PPAR agonists could be viable options for controlling the neurodegenerative symptoms and may be useful in treating AD.

Functional Signature of LRP4 Antibodies in Myasthenia Gravis.

Antibodies (Abs) specific for the low-density lipoprotein receptor-related protein 4 (LRP4) occur in up to 5% of patients with myasthenia gravis (MG). The objective of this study was to profile LRP4-Ab effector actions. We evaluated the efficacy of LRP4-specific compared with AChR-specific IgG to induce Ab-dependent cellular phagocytosis (ADCP), Ab-dependent cellular cytotoxicity (ADCC), and Ab-dependent complement deposition (ADCD). Functional features were additionally assessed in an independent AChR-Ab+ MG cohort. Levels of circulating activated complement proteins and frequency of Fc glycovariants were quantified and compared with demographically matched 19 healthy controls. Effector actions that required binding of Fc domains to cellular FcRs such as ADCC and ADCP were detectable for both LRP4-specific and AChR-specific Abs. In contrast to AChR-Abs, LRP4-binding Abs showed poor efficacy in inducing complement deposition. Levels of circulating activated complement proteins were not substantially increased in LRP4-Ab-positive MG. Frequency of IgG glycovariants carrying 2 sialic acid residues, indicative for anti-inflammatory IgG activity, was decreased in patients with LRP4-Ab-positive MG. LRP4-Abs are more effective in inducing cellular FcR-mediated effector mechanisms than Ab-dependent complement activation. Their functional signature is different from AChR-specific Abs.

A novel hypergraph model for identifying and prioritizing personalized drivers in cancer.

Cancer development is driven by an accumulation of a small number of driver genetic mutations that confer the selective growth advantage to the cell, while most passenger mutations do not contribute to tumor progression. The identification of these driver genes responsible for tumorigenesis is a crucial step in designing effective cancer treatments. Although many computational methods have been developed with this purpose, the majority of existing methods solely provided a single driver gene list for the entire cohort of patients, ignoring the high heterogeneity of driver events across patients. It remains challenging to identify the personalized driver genes. Here, we propose a novel method (PDRWH), which aims to prioritize the mutated genes of a single patient based on their impact on the abnormal expression of downstream genes across a group of patients who share the co-mutation genes and similar gene expression profiles. The wide experimental results on 16 cancer datasets from TCGA showed that PDRWH excels in identifying known general driver genes and tumor-specific drivers. In the comparative testing across five cancer types, PDRWH outperformed existing individual-level methods as well as cohort-level methods. Our results also demonstrated that PDRWH could identify both common and rare drivers. The personalized driver profiles could improve tumor stratification, providing new insights into understanding tumor heterogeneity and taking a further step toward personalized treatment. We also validated one of our predicted novel personalized driver genes on tumor cell proliferation by vitro cell-based assays, the promoting effect of the high expression of Low-density lipoprotein receptor-related protein 1 (LRP1) on tumor cell proliferation.

Lrp13a and Lrp13b serve as vitellogenin receptors in the ovary of zebrafish†.

In oviparous animals, egg yolk is largely derived from vitellogenin, which is taken up from the maternal circulation by the growing oocytes via the vitellogenin receptor. Recently, a novel member of the lipoprotein receptor superfamily termed low-density lipoprotein receptor-related protein 13 was identified and proposed as a candidate of vitellogenin receptor in oviparous animals. However, the roles of low-density lipoprotein receptor-related protein 13 in vitellogenesis are still poorly defined. Here, we investigated the expression, vitellogenin-binding properties, and function of low-density lipoprotein receptor-related protein 13 in zebrafish. Two different lrp13 genes termed lrp13a and lrp13b were found in zebrafish. Reverse transcription polymerase chain reaction and quantitative polymerase chain reaction revealed both lrp13s to be predominantly expressed in zebrafish ovary, and in situ hybridization detected both lrp13s transcripts in the ooplasm of early stage oocytes. Two yeast hybrid studies showed that among eight vitellogenins of zebrafish, Vtg1, 2, and 3 bind to Lrp13a, while Vtg1, 2, and 5 bind to Lrp13b. We created zebrafish lrp13a and lrp13b mutant lines using CRISPR/Cas9. Knockout of lrp13a leads to a male-biased sex ratio and decreased diameter of embryo yolk, while knockout of lrp13b and double knockout of lrp13a and lrp13b leads to the delay of vitellogenesis, followed by follicular atresia. These phenotypes of mutants can be explained by the disruption of vitellogenesis in the absence of Lrp13s. Taken together, our results indicate that both Lrp13a and Lrp13b can serve as vitellogenin receptors in zebrafish among other vitellogenin receptors that are not yet described.

Proteomic Analysis of Salivary Secretions from the Tea Green Leafhopper, Empoasca flavescens Fabrecius.

Saliva plays a crucial role in shaping the compatibility of piercing-sucking insects with their host plants. Understanding the complex composition of leafhopper saliva is important for developing effective and eco-friendly control strategies for the tea green leafhopper, Empoasca flavescens Fabrecius, a major piercing-sucking pest in Chinese tea plantations. This study explored the saliva proteins of tea green leafhopper adults using a custom collection device, consisting of two layers of Parafilm stretched over a sucrose diet. A total of 152 proteins were identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) following the filter-aided sample preparation (FASP). These proteins were categorized into six groups based on their functions, including enzymes, transport proteins, regulatory proteins, cell structure proteins, other proteins, and unknown proteins. Bioinformatics analyses predicted 16 secreted proteins, which were successfully cloned and transcriptionally analyzed across various tissues and developmental stages. Genes encoding putative salivary secretory proteins, including Efmucin1, EfOBP1, EfOBP2, EfOBP3, Efmucin2, low-density lipoprotein receptor-related protein (EfLRP), EFVg1, and EFVg2, exhibited high expressions in salivary gland (SG) tissues and feeding-associated expressions at different developmental stages. These findings shed light on the potential elicitors or effectors mediating the leafhopper feeding and defense responses in tea plants, providing insights into the coevolution of tea plants and leafhoppers. The study's conclusions open avenues for the development of innovative leafhopper control technologies that reduce the reliance on pesticides in the tea industry.

Clinical features, treatment, and follow-up of OPPG and high-bone-mass disorders: LRP5 is a key regulator of bone mass.

Low-density lipoprotein receptor-related protein 5 (LRP5) is involved in the canonical Wnt signaling pathway. The gain-of-function mutation leads to high bone mass (LRP5-HBM), while the loss-of-function mutation leads to osteoporosis-pseudoglioma syndrome (OPPG). In this study, the clinical manifestations, disease-causing mutations, treatment, and follow-up were summarized to improve the understanding of these two diseases. Two OPPG patients and four LRP5-HBM patients were included in this study. The clinical characteristics, biochemical and radiological examinations, pathogenic mutations, and structural analysis were summarized. Furthermore, several patients were followed up to observe the treatment effect and disease progress. Congenital blindness, persistent bone pain, low bone mineral density (BMD), and multiple brittle fractures were the main clinical manifestations of OPPG. Complex heterozygous mutations were detected in two OPPG patients. The c.1455G > T mutation in exon 7 was first reported. During the follow-up, BMD of two patients was significantly improved after bisphosphonate treatment. On the contrary, typical clinical features of LRP5-HBM included extremely high BMD without fractures, torus palatinus and normal vision. X-ray showed diffuse osteosclerosis. Two heterozygous missense mutations were detected in four patients. In addition, age-related bone loss was found in one LRP5-HBM patient after 12-year of follow-up. This study deepened the understanding of the clinical characteristics, treatment, and follow-up of OPPG and LRP5-HBM; expanded the pathogenic gene spectrum of OPPG; and confirmed that bisphosphonates were effective for OPPG. Additionally, it was found that Ala242Thr mutation could not protect LRP5-HBM patients from age-related bone loss. This phenomenon deserves further study.

Detection and Analysis of Genes Affecting the Number of Thoracic Vertebrae in Licha Black Pigs.

The number of thoracic vertebrae (NTV) in pigs is an important economic trait that significantly influences pork production. While the Licha black pig is a well-known Chinese pig breed with multiple thoracic vertebrae, the genetic mechanism is still unknown. Here, we performed a selective signal analysis on the genome of Licha black pigs, comparing individuals with 15 NTV versus those with 16 NTV to better understand functional genes associated with NTV. A total of 2265 selection signal regions were detected across the genome, including 527 genes and 1073 QTL that overlapped with the selection signal regions. Functional enrichment analysis revealed that LRP5 and SP5 genes were involved in biological processes such as bone morphogenesis and Wnt protein binding. Furthermore, three genes, LRP8, DEF6, and SCUBE3, associated with osteoblast differentiation and bone formation, were located within or close to the QTL related to bone development and vertebrae number. These five genes were hypothesized to be potential candidates for regulating the NTV trait in Licha black pigs. Our findings revealed several candidate genes that play crucial roles in NTV regulation and provide a theoretical foundation to understand the genetic mechanism of the NTV trait in pig breeding.

LDL receptor-related protein 5 selectively transports unesterified polyunsaturated fatty acids to intracellular compartments

Polyunsaturated fatty acids (PUFAs), which cannot be synthesized by animals and must be supplied from the diet, have been strongly associated with human health. However, the mechanisms for their accretion remain poorly understood. Here, we show that LDL receptor-related protein 5 (LRP5), but not its homolog LRP6, selectively transports unesterified PUFAs into a number of cell types. The LDLa ligand-binding repeats of LRP5 directly bind to PUFAs and are required and sufficient for PUFA transport. In contrast to the known PUFA transporters Mfsd2a, CD36 and FATP2, LRP5 transports unesterified PUFAs via internalization to intracellular compartments including lysosomes, and n-3 PUFAs depend on this transport mechanism to inhibit mTORC1. This LRP5-mediated PUFA transport mechanism suppresses extracellular trap formation in neutrophils and protects mice from myocardial injury during ischemia-reperfusion. Thus, this study reveals a biologically important mechanism for unesterified PUFA transport to intracellular compartments.

LRP1 facilitates hepatic glycogenesis by improving the insulin signaling pathway in HFD-fed mice.

LDL receptor-related protein-1 (LRP1) is a cell-surface receptor that functions in diverse physiological pathways. We previously demonstrated that hepatocyte-specific LRP1 deficiency (hLRP1KO) promotes diet-induced insulin resistance and increases hepatic gluconeogenesis in mice. However, it remains unclear whether LRP1 regulates hepatic glycogenesis. Insulin signaling, glycogenic gene expression, and glycogen content were assessed in mice and HepG2 cells. The pcDNA 3.1 plasmid and adeno-associated virus serotype 8 vector (AAV8) were used to overexpress the truncated β-chain (β∆) of LRP1 both invitro and invivo. On a normal chow diet, hLRP1KO mice exhibited impaired insulin signaling and decreased glycogen content. Moreover, LRP1 expression in HepG2 cells was significantly repressed by palmitate in a dose- and time-dependent manner. Both LRP1 knockdown and palmitate treatment led to reduced phosphorylation of Akt and GSK3β, increased levels of phosphorylated glycogen synthase (GYS), and diminished glycogen synthesis in insulin-stimulated HepG2 cells, which was restored by exogenous expression of the β∆-chain. By contrast, AAV8-mediated hepatic β∆-chain overexpression significantly improved the insulin signaling pathway, thus activating glycogenesis and enhancing glycogen storage in the livers of high-fat diet (HFD)-fed mice. Our data revealed that LRP1, especially its β-chain, facilitates hepatic glycogenesis by improving the insulin signaling pathway, suggesting a new therapeutic strategy for hepatic insulin resistance-related diseases.

LDL Receptor-Related Protein 1B Polymorphisms Associated with Increased Risk of Lymph Node Metastasis in Oral Cancer Group with Diabetes Mellitus.

Oral cancer ranks fourth among malignancies among Taiwanese men and is the eighth most common cancer among men worldwide in terms of general diagnosis. The purpose of the current study was to investigate how low-density lipoprotein receptor-related protein 1B (LDL receptor related protein 1B; LRP1B) gene polymorphisms affect oral squamous cell carcinoma (OSCC) risk and progression in individuals with diabetes mellitus (DM). Three LRP1B single-nucleotide polymorphisms (SNPs), including rs10496915, rs431809, and rs6742944, were evaluated in 311 OSCC cases and 300 controls. Between the case and control groups, we found no evidence of a significant correlation between the risk of OSCC and any of the three specific SNPs. Nevertheless, in evaluating the clinicopathological criteria, individuals with DM who possess a minimum of one minor allele of rs10496915 (AC + CC; p = 0.046) were significantly associated with tumor size compared with those with homozygous major alleles (AA). Similarly, compared to genotypes homologous for the main allele (GG), rs6742944 genotypes (GA + AA; p = 0.010) were more likely to develop lymph node metastases. The tongue and the rs6742944 genotypes (GA + AA) exhibited higher rates of advanced clinical stages (p = 0.024) and lymph node metastases (p = 0.007) when compared to homozygous alleles (GG). LRP1B genetic polymorphisms appear to be prognostic and diagnostic markers for OSCC and DM, as well as contributing to genetic profiling research for personalized medicine.

Lrp8 knockout mice fed a selenium-replete diet display subtle deficits in their spatial learning and memory function.

Selenium is an essential trace element that is delivered to the brain by the selenium transport protein selenoprotein P (SEPP1), primarily by binding to its receptor low-density lipoprotein receptor-related protein 8 (LRP8), also known as apolipoprotein E receptor 2 (ApoER2), at the blood-brain barrier. Selenium transport is required for several important brain functions, with transgenic deletion of either Sepp1 or Lrp8 resulting in severe neurological dysfunction and death in mice fed a selenium-deficient diet. Previous studies have reported that although feeding a standard chow diet can prevent these severe deficits, some motor coordination and cognitive dysfunction remain. Importantly, no single study has directly compared the motor and cognitive performance of the Sepp1 and Lrp8 knockout (KO) lines. Here, we report the results of a comprehensive parallel analysis of the motor and spatial learning and memory function of Sepp1 and Lrp8 knockout mice fed a standard mouse chow diet. Our results revealed that Sepp1 knockout mice raised on a selenium-replete diet displayed motor and cognitive function that was indistinguishable from their wild-type littermates. In contrast, we found that although Lrp8-knockout mice fed a selenium-replete diet had normal motor function, their spatial learning and memory showed subtle deficits. We also found that the deficit in baseline adult hippocampal neurogenesis exhibited by Lrp8-deficit mice could not be rescued by dietary selenium supplementation. Taken together, these findings further highlight the importance of selenium transport in maintaining healthy brain function. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Enhanced LRP8 expression induced by Helicobacter pylori drives gastric cancer progression by facilitating β-Catenin nuclear translocation

IntroductionHelicobacter pylori (H. pylori) infection has been associated with gastric carcinogenesis. However, the precise involvement of LRP8, the low-density lipoprotein receptor-related protein 8, in H. pylori pathogenesis and gastric cancer (GC) remains poorly understood. ObjectivesTo investigate the potential role of LRP8 in H. pylori infection and gastric carcinogenesis. MethodsThree-dimensional human-derived gastric organoids (hGO) and gastric cancer organoids (hGCO) were synthesized from the tissues obtained from human donors. In this work, multi-omics combined with in vivo and in vitro studies were conducted to investigate the potential involvement of LRP8 in H. pylori-induced GC. ResultsWe found that H. pylori infection significantly upregulated the expression of LRP8 in human GC tissues, cells, organoids, and mouse gastric mucous. In particular, LRP8 exhibited a distinct enrichment in cancer stem cells (CSC). Functionally, silencing of LRP8 affected the formation and proliferation of tumor spheroids, while increased expression of LRP8 was associated with increased proliferation and stemness of GC cells and organoids. Mechanistically, LRP8 promotes the binding of E-cadherin to β-catenin, thereby promoting nuclear translocation and transcriptional activity of β-catenin. Furthermore, LRP8 interacts with the cytotoxin-associated gene A (CagA) to form the CagA/LRP8/β-catenin complex. This complex further amplifies H. pylori-induced β-catenin nuclear translocation, leading to increased transcription of inflammatory factors and CSC markers. Clinical analysis demonstrated that abnormal overexpression of LRP8 is correlated with a poor prognosis and resistance to 5-Fluorouracil in patients with GC. ConclusionOur findings provide valuable information on the molecular intricacies of H. pylori-induced gastric carcinogenesis, offering potential therapeutic targets and prognostic markers for GC.

Efficacy of Sailuotong on neurovascular unit in amyloid precursor protein/presenilin-1 transgenic mice with Alzheimer's disease.

To discuss the influence of Sailuotong (, SLT) on the Neurovascular Unit (NVUs) of amyloid precursor protein (APP)/presenilin-1(PS1) mice and evaluate the role of gas supplementation in activating blood circulation during the progression of Alzheimer's disease (AD). The mice were allocated into the following nine groups: (a) the C57 Black (C57BL) sham-operated group (control group), (b) ischaemic treatment in C57BL mice (the C57 ischaemic group), (c) the APP/PS1 sham surgery group (APP/PS1 model group), (d) ischaemic treatment in APP/PS1 mice (APP/PS1 ischaemic group), (e) C57BL mice treated with aspirin following ischaemic treatment (C57BL ischaemic + aspirin group), (f) C57BL mice treated with SLT following ischaemic treatment (C57BL ischaemic + SLT group), (g) APP/PS1 mice treated with SLT (APP/PS1 + SLT group), (h) APP/PS1 mice treated with donepezil hydrochloride following ischaemic treatment (APP/PS1 ischaemic + donepezil hydrochloride group) and (i) APP/PS1 mice treated with SLT following ischaemic treatment (APP/PS1 ischaemic + SLT group). The ischaemic model was established by operating on the bilateral common carotid arteries and creating a microembolism. The Morris water maze and step-down tests were used to detect the spatial behaviour and memory ability of mice. The hippocampus of each mouse was observed by haematoxylin and eosin (HE) and Congo red staining. The ultrastructure of NVUs in each group was observed by electron microscopy, and various biochemical indicators were detected by enzyme-linked immunosorbent assay (ELISA). The protein expression level was detected by Western blot. The mRNA expression was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The results of the Morris water maze and step-down tests showed that ischemia reduced learning and memory in the mice, which were restored by SLT. The results of HE staining showed that SLT restored the pathological changes of the NVUs. The Congo red staining results revealed that SLT also improved the scattered orange-red sediments in the upper cortex and hippocampus of the APP/PS1 and APP/PS1 ischaemic mice. Furthermore, SLT significantly reduced the content of Aβ, improved the vascular endothelium and repaired the mitochondrial structures. The ELISA detection, western blot detection and qRT-PCR showed that SLT significantly increased the vascular endothelial growth factor (VEGF), angiopoietin and basic fibroblast growth factor, as well as the levels of gene and protein expression of low-density lipoprotein receptor-related protein-1 (LRP-1) and VEGF in brain tissue. By increasing the expression of VEGF, SLT can promote vascular proliferation, up-regulate the expression of LRP-1, promote the clearance of Aβ and improve the cognitive impairment of APP/PS1 mice. These results confirm that SLT can improve AD by promoting vascular proliferation and Aβ clearance to protect the function of NVUs.

17 variants interaction of Wnt/β-catenin pathway associated with development of osteonecrosis of femoral head in Chinese Han population

The genes of Wnt/β-catenin pathway may have potential roles in fat accumulation of Non-traumatic osteonecrosis of the femoral head (ONFH), but the effects of their variants in the pathway on ONFH development have been remained unclear. To explore the potential roles of the variants in the development of ONFH, we completed the investigation of the paired interactions as well as their related biological functions of 17 variants of GSK3β, LRP5, and FRP4 genes etc. in the pathway. The genotyping of the 17 variants were finished by MASS ARRAY PLATFORM in a 560 ONFH case–control system. The association of variants interactions with ONFH risk and clinical traits was evaluated by logistic regression analysis etc. and bioinformatics technology. The results showed that the genotype, allele frequency, and genetic models of Gsk3β rs334558 (G/A), SFRP4 rs1052981 (A/G), and LRP5 rs312778 (T/C) were significantly associated with the increased and decreased ONFH risk and clinical traits, respectively (P < 0.001–0.0002). Particularly, the paired interactions of six variants as well as eight variants also showed statistically increased and decreased ONFH risk, bilateral hip lesions risk and stage IV risk of ONFH, respectively (P < 0.044–0.004). Our results not only at the first time simultaneously showed exact serum lipid disorder and abnormal platelet function of ONFH in the same study system with the 17 variants polymorphisms of Wnt/β-catenin pathway but also shed light on the variants closely intervening the lipid disorder and abnormal coagulation of ONFH.

Low-density lipoprotein receptor-related protein 5/6 promotes endometrial cancer progression and cancer cell immune escape.

The study investigated the potential association of the low-density lipoprotein (LDL) genome with endometrial cancer progression based on the Gene Expression Omnibus data set and The Cancer Genome Atlas data set. Differential and weighted gene coexpression network analysis was performed on endometrial cancer transcriptome datasets GSE9750 and GSE106191. The protein-protein interaction network was built using LDL-receptor proteins and the top 50 tumor-associated genes. Low-density lipoprotein-related receptors 5/6 (LRP5/6) in endometrial cancer tissues were correlated with oncogenes, cell cycle-related genes, and immunological checkpoints using Spearman correlation. MethPrimer predicted the LRP5/6 promoter CpG island. LRP2, LRP6, LRP8, LRP12, low-density lipoprotein receptor-related protein-associated protein, and LRP5 were major LDL-receptor-related genes associated with endometrial cancer. LRP5/6 was enriched in various cancer-related pathways and may be a key LDL-receptor-related gene in cancer progression. LRP5/6 may be involved in the proliferation process of endometrial cancer cells by promoting the expression of cell cycle-related genes. LRP5/6 may be involved in the proliferation of endometrial cancer cells by promoting the expression of cell cycle-related genes. LRP5/6 may promote the immune escape of cancer cells by promoting the expression of immune checkpoints, promoting endometrial cancer progression. The MethPrimer database predicted that the LRP5/6 promoter region contained many CpG islands, suggesting that DNA methylation can occur in the LRP5/6 promoter region. LRP5/6 may aggravate endometrial cancer by activating the phosphoinositide 3-kinase/protein kinase B pathway.

Abstract 1374: Targeting CD47/SIRPɑ axis in urologic cancer triggers enhanced phagocytosis of tumor cell and induces tumor growth inhibition

Abstract Signal regulatory protein-α (SIRPα; CD172a or SHPS-1) is a transmembrane molecule that highly expressed on myeloid population. Binding of CD47 (integrin-associated protein, IAP) to SIRPα inhibits phagocytosis in macrophages, which acts as a mechanism of maintaining homeostasis. Tumor cells however, often time upregulate CD47 to evade immune response. Using publicly available dataset, we found that human prostate cancer cells upregulate expression of both CD47 and calreticulin, a “eat me” signal when engaged with Low density lipoprotein receptor-related protein 1 (LRP1). In addition, macrophages, monocytes and dendritic cells in human prostate cancer do have relatively high level of SIRPɑ and LRP1 expression. This finding provides the rationale of targeting CD47/SIRPɑ axis in prostate cancer to shift the balance between pro-phagocytosis and anti-phagocytosis signaling. We then moved to RM1 and B6Cap, two syngeneic prostate cancer models in immunocompetent mice. Significant tumor growth inhibition was seen in both models with anti SIRPɑ blocking antibody. Furthermore, we observed in vitro that CD47 or SIRPɑ blockage led to enhanced PC3 cell line phagocytosis by human monocyte derived macrophages (HMDMs). Same finding was found using mouse bone marrow derived macrophages (BMDMs). We then utilized ovalbumin expressing MB49 bladder cancer cell line and cocultured those with BMDMs. CD8+ T cell from OT1 mice exhibited higher expression of activation makers when cocultured BMDMs treated by either anti CD47 or SIRPɑ antibody, indicating that enhanced phagocytosis subsequently increases antigen cross presentation in macrophages. In summary, we identified that CD47 is overexpressed in human prostate cancer; blocking CD47/SIRPɑ did inhibit tumor growth through enhanced phagocytosis and antigen presentation. Citation Format: Fan Shen, Monali Praharaj, Alex J. Lee, Thomas R. Nirschl, Xiaoxu Wang. Targeting CD47/SIRPɑ axis in urologic cancer triggers enhanced phagocytosis of tumor cell and induces tumor growth inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1374.

Abstract 3005: Low-density lipoprotein receptor-related protein 1B (LRP1B) depletion promotes tumorigenicity by modulating fibroblasts in the tumor microenvironment in esophageal squamous cell carcinoma

Abstract Background: Esophageal squamous cell carcinoma (ESCC) is widespread worldwide with a poor survival rate. Tumor cells shedding from tumor tissues traveling to other organs through the blood circulatory system are called circulating tumor cells (CTCs). The CTCs in the blood of ESCC patients were enriched and then subjected to CTC mutational profiling by target sequencing. Our results suggested that CTC mutations in low-density lipoprotein receptor-related protein 1B (LRP1B) may have a potential prognostic role for ESCC. LRP1B belongs to the low-density receptor (LDLR) family with diverse roles in cellular functions and development, but the function of LRP1B in ESCC remains unclear. Therefore, this study aims to do a functional characterization of LRP1B. Methods: The CRISPR cas9 system was used to functionally knock down the candidate gene in ESCC cell lines with the highest endogenous level of LRP1B. The in vitro cell proliferation rate and viability were measured by MTT assay, colony formation assay, and wound healing assay. The in vivo tumorigenicity assay was performed to evaluate the tumor suppressive effect by subcutaneous injection. To examine the clinical relevance of LRP1B, we also performed immunohistochemistry (IHC) in tumor tissue microarray (TMA). Results: The reduction or loss of LRP1B mRNA was demonstrated in 60% of a panel of 15 ESCC cell lines. The depletion of LRP1B did not influence cell proliferation, cell clonogenic ability, or cell migration in ECSS cell lines. However, LRP1B depletion significantly promoted the growth of tumors in mouse xenograft models. Therefore, we hypothesize that LRP1B may be involved in modulating the tumor microenvironment (TME) by impacting various stromal components leading to an immuno-suppressive TME. We utilized RT-qPCR to investigate markers of various stromal components and observed that fibroblast markers (acta2, pdgfrb, and vimentin) had significantly higher expression levels after LRP1B downregulation in ESCC cell-derived mouse xenografts. The higher level of fibroblast cells was then verified by IHC staining. Further molecular mechanistic studies are underway and are expected to provide novel therapeutic insights by targeting the LRP1B genes. The LRP1B ESCC TMA data analysis is underway and statistical analysis will be presented. Conclusions: LRP1B plays a tumor-suppressive role in ESCC by modulating the tumor-associated fibroblasts in the TME. Acknowledgements: TBRS grant T12-701/17R and HMRF grant 05160926 to MLL Citation Format: KaiYan Xu, Josephine Mun-yee KO, Valen Zhuo you Yu, Maria Li LUNG. Low-density lipoprotein receptor-related protein 1B (LRP1B) depletion promotes tumorigenicity by modulating fibroblasts in the tumor microenvironment in esophageal squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3005.

Peripheral amyloid-β clearance mediates cognitive impairment in non-alcoholic fatty liver disease

BackgroundNon-alcoholic fatty liver disease (NAFLD) is a prevalent risk factor for cognitive impairment. Cerebral amyloid-β (Aβ) accumulation, as an important pathology of cognitive impairment, can be caused by impaired Aβ clearance in the periphery. The liver is the primary organ for peripheral Aβ clearance, but the role of peripheral Aβ clearance in NAFLD-induced cognitive impairment remains unclear. MethodsWe examined correlations between NAFLD severity, Aβ accumulation, and cognitive performance in female Sprague-Dawley rats. The impact of NAFLD on hepatic Aβ clearance and the involvement of low-density lipoprotein receptor-related protein 1 (LRP-1) were assessed in rat livers and cultured hepatocytes. Additionally, a case-control study, including 549 NAFLD cases and 549 controls (782 males, 316 females), investigated the interaction between NAFLD and LRP-1 rs1799986 polymorphism on plasma Aβ levels. FindingsThe severity of hepatic steatosis and dysfunction closely correlated with plasma and cerebral Aβ accumulations and cognitive deficits in rats. The rats with NAFLD manifested diminished levels of LRP-1 and Aβ in liver tissue, with these reductions inversely proportional to plasma and cerebral Aβ concentrations and cognitive performance. In vitro, exposure of HepG2 cells to palmitic acid inhibited LRP-1 expression and Aβ uptake, which was subsequently reversed by a peroxisome proliferator-activated receptor α (PPARα) agonist. The case-control study revealed NAFLD to be associated with an increment of 8.24% and 10.51% in plasma Aβ40 and Aβ42 levels, respectively (both P <0.0001). Moreover, the positive associations between NAFLD and plasma Aβ40 and Aβ42 levels were modified by the LRP-1 rs1799986 polymorphism (P for interaction = 0.0017 and 0.0015, respectively). InterpretationLRP-1 mediates the adverse effect of NAFLD on peripheral Aβ clearance, thereby contributing to cerebral Aβ accumulation and cognitive impairment in NAFLD. FundingMajor International (Regional) Joint Research Project, National Key Research and Development Program of China, National Natural Science Foundation of China, and the Angel Nutrition Research Fund.

Apolipoprotein E-containing lipoproteins and their extracellular interactions with LRP1 affect LPS-induced inflammation.

The linkage between low-density lipoprotein receptor-related protein (LRP)1-mediated metabolism of apolipoprotein (apo) E-containing lipoproteins (apoE-LP) and the lipopolysaccharide (LPS)-induced inflammatory response contributes to the pathogenesis of sepsis; however, the underlying mechanisms are unclear. Therefore, in this study, the effects of apoE-LP and their constituents on the mRNA expression of interleukin (IL)-6 and LRP1 were evaluated using a culture system of human fibroblasts supplemented with LPS and apoE-containing emulsion particles (apoE-EP). The affinity of apoE-LP for LPS was examined using the interaction between fluorescence-labeled LPS and serum lipoprotein fractions. LPS-induced inflammation significantly upregulated the mRNA expression of IL-6 andLRP1. This upregulation was markedly suppressed by pre-incubation of LPS with apoE-EP or its constituents (apoE or EP). The suppressive effect of apoE-EP on IL-6 upregulation was attenuated in the presence of lactoferrin, an inhibitor of LRP1. The prepared apoE-EP and serum triglyceride-rich lipoproteins showed significant affinity for LPS. However, these affinities appeared to be lower than expected based on the extent to which IL-6 upregulation was suppressed by pre-incubation of LPS with apoE-EP. Overall, these results indicate that LPS-induced inflammation may be regulated by1) the LPS-neutralizing effect of apoE-LP, 2) anti-inflammatory effect of apoE, and 3) LRP1-mediated metabolic pathways.

Aging and brain free cholesterol concentration on amyloid-β peptide accumulation in guinea pigs.

Alzheimer's disease is a complex multifactorial neurodegenerative disorder wherein age is a major risk factor. The appropriateness of the Hartley guinea pig (GP), which displays high sequence homologies of its amyloid-β (Aβ40 and Aβ42) peptides, Mdr1 and APP(amyloid precursor protein) and similarity in lipid handling to humans, was appraised among 9-40weeks old guinea pigs. Protein expression levels of P-gp (Abcb1) and Cyp46a1 (24(S)-hydroxylase) for Aβ40, and Aβ42 efflux and cholesterol metabolism, respectively, were decreased with age, whereas those for Lrp1 (low-density lipoprotein receptor related protein 1), Rage (receptor for advanced glycation endproducts) for Aβ efflux and influx, respectively, and Abca1 (the ATP binding cassette subfamily A member 1) for cholesterol efflux, were unchanged among the ages examined. There was a strong, negative correlation of the brain Aβ peptide concentrations and Abca1 protein expression levels with free cholesterol. The correlation of Aβ peptide concentrations with Cyp46a1 was, however, not significant, and concentrations of the 24(S)-hydroxycholesterol metabolite revealed a decreasing trend from 20weeks old toward 40weeks old guinea pigs. The composite data suggest a role for free cholesterol on brain Aβ accumulation. The decreases in P-gp and Lrp1 protein levels should further exacerbate the accumulation of Aβ peptides in guinea pig brain.