The tumor suppressor function of LECT2 in human hepatocellular carcinoma makes it a potential therapeutic target

Global research trends and hotspots for leukocyte cell-derived chemotaxin-2 from the past to 2023: a combined bibliometric review

Leukocyte cell-derived chemotaxin-2 (LECT2) is an important cytokine synthesized by liver. Significant research interest is stimulated by its crucial involvement in inflammatory response, immune regulation, disease occurrence and development. However, bibliometric study on LECT2 is lacking. In order to comprehend the function and operation of LECT2 in human illnesses, we examined pertinent studies on LECT2 investigation in the Web of Science database, followed by utilizing CiteSpace, VOSview, and Scimago Graphica for assessing the yearly quantity of papers, countries/regions involved, establishments, authors, publications, citations, and key terms. Then we summarized the current research hotspots in this field. Our study found that the literature related to LECT2 has a fluctuating upward trend. "Angiogenesis", "ALECT2", "diagnosis", and "biliary atresia" are the current investigative frontiers. Our findings indicated that liver diseases (e.g. liver fibrosis and hepatic cell carcinoma), systemic inflammatory disease, and amyloidosis are the current research focus of LECT2. The current LECT2 research outcomes are not exceptional. We hope to promote the scientific research of LECT2 and exploit its potential for clinical diagnosis and treatment of related diseases through a comprehensive bibliometric review.

A Critical Review on the Role of Probiotics in Lung Cancer Biology and Prognosis

Lung cancer remains the leading cause of cancer-related deaths worldwide. According to the American Cancer Society (ACS), it ranks as the second most prevalent type of cancer globally. Recent findings have highlighted bidirectional gut-lung interactions, known as the gut-lung axis, in the pathophysiology of lung cancer. Probiotics are live microorganisms that boost host immunity when consumed adequately. The immunoregulatory mechanisms of probiotics are thought to operate through the generation of various metabolites that impact both the gut and distant organs (e.g., the lungs) through blood. Several randomized controlled trials have highlighted the pivotal role of probiotics in gut health especially for the prevention and treatment of malignancies, with a specific emphasis on lung cancer. Current research indicates that probiotic supplementation positively affects patients, leading to a suppression in cancer symptoms and a shortened disease course. While clinical trials validate the therapeutic benefits of probiotics, their precise mechanism of action remains unclear. This narrative review aims to provide a comprehensive overview of the present landscape of probiotics in the management of lung cancer.

Loss of LECT2 promotes ovarian cancer progression by inducing cancer invasiveness and facilitating an immunosuppressive environment

Leukocyte cell-derived chemotaxin 2 (LECT2) is a multifunctional cytokine that can bind to several receptors and mediate distinct molecular pathways in various cell settings. Changing levels of LECT2 have been implicated in multiple human disease states, including cancers. Here, we have demonstrated reduced serum levels of LECT2 in patients with epithelial ovarian cancer (EOC) and down-regulated circulating Lect2 as the disease progresses in a syngeneic mouse ID8 EOC model. Using the murine EOC model, we discovered that loss of Lect2 promotes EOC progression by modulating both tumor cells and the tumor microenvironment. Lect2 inhibited EOC cells' invasive phenotype and suppressed EOC's transcoelomic metastasis by targeting c-Met signaling. In addition, Lect2 downregulation induced the accumulation and activation of myeloid-derived suppressor cells (MDSCs). This fostered an immunosuppressive microenvironment in EOC by inhibiting T-cell activation and skewing macrophages toward an M2 phenotype. The therapeutic efficacy of programmed cell death-1 (PD-1)/PD-L1 pathway blockade for the ID8 model was significantly hindered. Overall, our data highlight multiple functions of Lect2 during EOC progression and reveal a rationale for synergistic immunotherapeutic strategies by targeting Lect2.

Splice-switch oligonucleotide-based combinatorial platform prioritizes synthetic lethal targets CHK1 and BRD4 against MYC-driven hepatocellular carcinoma

Deregulation of MYC is among the most frequent oncogenic drivers in hepatocellular carcinoma (HCC). Unfortunately, the clinical success of MYC-targeted therapies is limited. Synthetic lethality offers an alternative therapeutic strategy by leveraging on vulnerabilities in tumors with MYC deregulation. While several synthetic lethal targets of MYC have been identified in HCC, the need to prioritize targets with the greatest therapeutic potential has been unmet. Here, we demonstrate that by pairing splice-switch oligonucleotide (SSO) technologies with our phenotypic-analytical hybrid multidrug interrogation platform, quadratic phenotypic optimization platform (QPOP), we can disrupt the functional expression of these targets in specific combinatorial tests to rapidly determine target-target interactions and rank synthetic lethality targets. Our SSO-QPOP analyses revealed that simultaneous attenuation of CHK1 and BRD4 function is an effective combination specific in MYC-deregulated HCC, successfully suppressing HCC progression in vitro. Pharmacological inhibitors of CHK1 and BRD4 further demonstrated its translational value by exhibiting synergistic interactions in patient-derived xenograft organoid models of HCC harboring high levels of MYC deregulation. Collectively, our work demonstrates the capacity of SSO-QPOP as a target prioritization tool in the drug development pipeline, as well as the therapeutic potential of CHK1 and BRD4 in MYC-driven HCC.

Comprehensive analysis of SLC43A2 on the tumor immune microenvironment and prognosis of liver hepatocellular carcinoma

Background: Tumor cells outcompete T cells for methionine via overexpressing SLC43A2, causing T cells exhaustion. We explored the influence of SLC43A2 on tumor immune microenvironment (TIME), immune-related genes (IRGs) and the prognosis of liver hepatocellular carcinoma (LIHC) patients.

Methods: The TCGA-LIHC dataset (n = 374) and the ICGC-LIRI-JP-LIHC (n = 231) datasets were used as training and validation cohort, respectively. IRGs were obtained from ImmPort. Statistical analyses were performed using R (V 4.0.5). Online databases such as GEPIA, GSCALite, the Kaplan–Meier plotter, KEGG, TIMER2, and CMap were used for differential expression, immune infiltration, functional enrichment, survival, and drug-induced gene perturbation analysis.

Results: SLC43A2 expression was higher in LIHC, correlated with worse survival, but could not predict prognosis of LIHC separately (AUC = 0.467). SLC43A2 positively correlated with immune exhaustion markers (all p < 0.001) and with increased infiltration of Tregs, macrophages and myeloid-derived suppressor cells (MDSC) (all p < 0.05). SLC43A2 may regulate 120 IRGs. A prognostic risk score model was developed using the TCGA-LIHC cohort and validated by the ICGC-LIRI-JP cohort. Arachidonic acid, SB-202190 and guanethidine were identified as possible immunomodulators pharmacologically targeting SLC43A2 in LIHC.

Conclusion: SLC43A2 may create suppressive tumor microenvironment and regulate related IRGs, thus affecting the prognosis of LIHC. Arachidonic acid, SB-202190, and guanethidine may be worthy of further study as immunomodulators on SLC43A2.

A strategy of vascular-targeted therapy for liver fibrosis

BACKGROUND AND AIMS

No effective treatments are available for liver fibrosis. Angiogenesis is deeply involved in liver fibrogenesis. However, current controversial results suggest it is difficult to treat liver fibrosis through vascular targeting. There are three different microvessels in liver: portal vessels, liver sinusoids, and central vessels. The changes and roles for each of the three different vessels during liver fibrogenesis are unclear. We propose that they play different roles during liver fibrogenesis, and a single vascular endothelial cell (EC) regulator is not enough to fully regulate these three vessels to treat liver fibrosis. Therefore, a combined regulation of multiple different EC regulatory signaling pathway may provide new strategies for the liver fibrosis therapy. Herein, we present a proof-of-concept strategy by combining the regulation of leukocyte cell-derived chemotaxin 2 (LECT2)/tyrosine kinase with immunoglobulin-like and epidermal growth factor-like domains 1 signaling with that of vascular endothelial growth factor (VEGF)/recombinant VEGF (rVEGF) signaling.

APPROACH AND RESULTS

The CCl₄ -induced mouse liver fibrosis model and NASH model were both used. During fibrogenesis, vascular changes occurred at very early stage, and different liver vessels showed different changes and played different roles: decreased portal vessels, increased sinusoid capillarization and the increased central vessels the increase of portal vessels alleviates liver fibrosis, the increase of central vessels aggravates liver fibrosis, and the increase of sinusoid capillarization aggravates liver fibrosis. The combinational treatment of adeno-associated viral vector serotype 9 (AAV9)-LECT2-short hairpin RNA (shRNA) and rVEGF showed improved therapeutic effects, but it led to serious side effects. The combination of AAV9-LECT2-shRNA and bevacizumab showed both improved therapeutic effects and decreased side effects.

CONCLUSIONS

Liver vascular changes occurred at very early stage of fibrogenesis. Different vessels play different roles in liver fibrosis. The combinational treatment of AAV9-LECT2-shRNA and bevacizumab could significantly improve the therapeutic effects on liver fibrosis.

Leukocyte cell-derived chemotaxin 2 regulates epithelial-mesenchymal transition and cancer stemness in hepatocellular carcinoma

Leukocyte cell-derived chemotaxin 2 (LECT2) acts as a tumor suppressor in hepatocellular carcinoma (HCC). However, the antineoplastic mechanism of LECT2, especially its influence on hepatic cancer stem cells (CSCs), remains largely unknown. In The Cancer Genome Atlas cohort, LECT2 mRNA expression was shown to be associated with stage, grade, recurrence, and overall survival in human HCC patients, and LECT2 expression was downregulated in hepatoma tissues compared with the adjacent nontumoral liver. Here, we show by immunofluorescence and immunoblot analyses that LECT2 was expressed at lower levels in tumors and in poorly differentiated HCC cell lines. Using functional assays, we also found LECT2 was capable of suppressing oncogenic behaviors such as cell proliferation, anchorage-independent growth, migration, invasiveness, and epithelial-mesenchymal transition in hepatoma cells. Moreover, we show exogenous LECT2 treatment inhibited CSC functions such as tumor sphere formation and drug efflux. Simultaneously, hepatic CSC marker expression was also downregulated, including expression of CD133 and CD44. This was supported by infection with adenovirus encoding LECT2 (Ad-LECT2) in HCC cells. Furthermore, in animal experiments, Ad-LECT2 gene therapy showed potent efficacy in treating HCC. We demonstrate LECT2 overexpression significantly promoted cell apoptosis and reduced neovascularization/CSC expansion in rat hepatoma tissues. Mechanistically, we showed using immunoblot and immunofluorescence analyses that LECT2 inhibited β-catenin signaling via the suppression of the hepatocyte growth factor/c-MET axis to diminish CSC properties in HCC cells. In summary, we reveal novel functions of LECT2 in the suppression of hepatic CSCs, suggesting a potential alternative strategy for HCC therapy.

LECT2: A pleiotropic and promising hepatokine, from bench to bedside

LECT2 (leucocyte cell-derived chemotaxin 2) is a 16-kDa protein mainly produced by hepatocytes. It was first isolated in PHA-activated human T-cell leukaemia SKW-3 cells and originally identified as a novel neutrophil chemotactic factor. However, many lines of studies suggested that LECT2 was a pleiotropic protein, it not only functioned as a cytokine to exhibit chemotactic property, but also played multifunctional roles in some physiological conditions and pathological abnormalities, involving liver regeneration, neuronal development, HSC(haematopoietic stem cells) homeostasis, liver injury, liver fibrosis, hepatocellular carcinoma, metabolic disorders, inflammatory arthritides, systemic sepsis and systemic amyloidosis. Among the above studies, it was discovered that LECT2 could be a promising molecular biomarker and therapeutic target. This review summarizes LECT2-related receptors and pathways, basic and clinical researches, primarily in mice and human, for a better comprehension and management of these diseases in the future.

The Crosstalk Between Liver Sinusoidal Endothelial Cells and Hepatic Microenvironment in NASH Related Liver Fibrosis

Chronic liver injury can be caused by many factors, including virus infection, alcohol intake, cholestasis and abnormal fat accumulation. Nonalcoholic steatohepatitis (NASH) has become the main cause of liver fibrosis worldwide. Recently, more and more evidences show that hepatic microenvironment is involved in the pathophysiological process of liver fibrosis induced by NASH. Hepatic microenvironment consists of various types of cells and intercellular crosstalk among different cells in the liver sinusoids. Liver sinusoidal endothelial cells (LSECs), as the gatekeeper of liver microenvironment, play an irreplaceable role in the homeostasis and alterations of liver microenvironment. Many recent studies have reported that during the progression of NASH to liver fibrosis, LSECs are involved in various stages mediated by a series of mechanisms. Therefore, here we review the key role of crosstalk between LSECs and hepatic microenvironment in the progression of NASH to liver fibrosis (steatosis, inflammation, and fibrosis), as well as promising therapeutic strategies targeting LSECs.

Enhanced Anti-Cancer Effects of Conditioned Medium from Hypoxic Human Adult Dermal Fibroblasts on Cervical Cancer Cells

Hypoxia regulates fibroblast function by changing intracellular signaling and secretion factors, that influence the states of nearby cells. In this work, we investigated how medium (CM) from human adult dermal fibroblasts (HDFs) cultured in normoxic and hypoxic conditions affected cervical cancer (HeLa) cells. The HeLa cells showed decreased cell viability, increased apoptosis, and cell cycle arrest in response to CM from hypoxic-cultured HDFs (H-CM) compared with CM from normoxic-cultured HDFs (N-CM). Among the proteins up-regulated (>2-fold) in H-CM compared with N-CM, lymphotoxin-beta receptor (LTBR) decreased the viability of HeLa cells. Among the intracellular proteins down-regulated (>2-fold) in HeLa cells treated with H-CM compared with N-CM, the most enriched biological process GO term and KEGG pathway were protein deubiquitination and hsa05166:HTLV-I infection, respectively. In the protein−protein interaction network of intracellular proteins with altered expression (>2-fold), 1 up-regulated (TNF) and 8 down-regulated (ESR1, MCL1, TBP, CD19, LCK, PCNA, CHEK1, and POLA1) hub proteins were defined. Among the down-regulated hub proteins, the most enriched biological process GO term and KEGG pathway were leading strand elongation and hsa05166:HTLV-I infection, respectively. This study reveals that H-CM had stronger anti-cancer effects on cervical cancer cells than N-CM and induced intracellular signaling patterns related to those enhanced anti-cancer effects.

Hepatic PTEN Signaling Regulates Systemic Metabolic Homeostasis through Hepatokines-Mediated Liver-to-Peripheral Organs Crosstalk

Liver-derived circulating factors deeply affect the metabolism of distal organs. Herein, we took advantage of the hepatocyte-specific PTEN knockout mice (LPTENKO), a model of hepatic steatosis associated with increased muscle insulin sensitivity and decreased adiposity, to identify potential secreted hepatic factors improving metabolic homeostasis. Our results indicated that protein factors, rather than specific metabolites, released by PTEN-deficient hepatocytes trigger an improved muscle insulin sensitivity and a decreased adiposity in LPTENKO. In this regard, a proteomic analysis of conditioned media from PTEN-deficient primary hepatocytes identified seven hepatokines whose expression/secretion was deregulated. Distinct expression patterns of these hepatokines were observed in hepatic tissues from human/mouse with NAFLD. The expression of specific factors was regulated by the PTEN/PI3K, PPAR or AMPK signaling pathways and/or modulated by classical antidiabetic drugs. Finally, loss-of-function studies identified FGF21 and the triad AHSG, ANGPTL4 and LECT2 as key regulators of insulin sensitivity in muscle cells and in adipocytes biogenesis, respectively. These data indicate that hepatic PTEN deficiency and steatosis alter the expression/secretion of hepatokines regulating insulin sensitivity in muscles and the lipid metabolism in adipose tissue. These hepatokines could represent potential therapeutic targets to treat obesity and insulin resistance.

LECT-2 amyloidosis: what do we know?

Amyloidosis is a rare group of diseases characterized by abnormal folding of proteins and extracellular deposition of insoluble fibrils. It can be localized to one organ system or can have systemic involvement. The kidney is the most common organ to be involved in systemic amyloidosis often leading to renal failure and the nephrotic syndrome. The two most common types of renal amyloidosis are immunoglobulin light chain-derived amyloidosis (AL) and reactive amyloidosis (AA). A novel form of amyloidosis (ALECT2) derived from leukocyte chemotactic factor 2 (LECT-2) and primarily involving the kidneys was first described by Benson et al in 2008. The liver was subsequently identified as the second most common organ involved in ALECT2 amyloidosis. LECT-2 is a unique protein that can form amyloid deposits even in its unmutated form. Patients with ALECT2 present with minimal proteinuria in contrast to other forms of amyloidosis especially AL and AA. They may present with slightly elevated serum creatinine. Nephrotic syndrome and hematuria are rare. ALECT2 can be found in association with other types of amyloidosis as well as malignancies or autoimmune diseases. ALECT2 may be confused with amyloidosis associated with light and heavy chain monoclonal gammopathy if the immunofluorescence is positive with anti-light chain and anti-AA sera. The other organs involved are the duodenum, adrenal gland, spleen, prostate, gall bladder, pancreas, small bowel, parathyroid gland, heart, and pulmonary alveolar septa, but consistently uninvolved organs included brain and fibroadipose tissue. A renal biopsy along with characteristic features found on immunohistochemistry and mass spectrometry is diagnostic of ALECT2. ALECT2 should be suspected when all markers for AL and AA are negative. Proper diagnosis of ALECT2 can determine need for supportive care versus more aggressive interventions.

LECT2, A Novel and Direct Biomarker of Liver Fibrosis in Patients With CHB

Chronic hepatitis B (CHB) patients with severe liver fibrosis would be more likely to progress to a poorer prognosis. Treatment is considered once the liver fibrosis reaches significant liver fibrosis (≥S2). Leukocyte cell-derived chemotaxin-2 (LECT2) has been shown to contribute to liver fibrosis progression. No research has focused on the role of LECT2 in liver fibrosis in CHB patients. This study enrolled 227 CHB patients and divided them into the training group (n = 147) and validation group (n = 80), respectively. The expression of LECT2 in serum, protein and mRNA of the human liver tissues was detected to analyze the possible associations between LECT2 and liver fibrosis. A receiver operating characteristic curve (ROC) was used to estimate the efficacy of LECT2 for predicting liver fibrosis. The data showed that there was a positive relationship between LECT2 and the progression of liver fibrosis. In the training group, LECT2 was demonstrated to have better effectiveness than APRI and FIB-4. The AUC was 0.861, 0.698, and 0.734 for significant liver fibrosis, and 0.855, 0.769, and 0.752 for advanced liver fibrosis. Besides, the efficacy of LECT2 in different statuses of patients with CHB was examined and the effectiveness of LECT2 had also been confirmed in the validation group. All the results confirmed that LECT2 could act as a perfect predictor and thus offers a novel and direct biomarker to estimate liver fibrosis more accurately.

The molecular structure and role of LECT2 or CHM-II in arthritis, cancer, and other diseases

Leukocyte cell-derived chemotaxin-2 (LECT2 or LECT-2), also called chondromodulin II (ChM-II or CHM2) plays a versatile role in various tissues. It was first identified as a chemotactic factor to promote the migration of neutrophils. It was also reported as a hepatokine to regulate glucose metabolism, obesity, and nonalcoholic fatty liver disease. As a secreted factor, LECT2 binds to several cell surface receptors CD209a, Tie1, and Met to regulate inflammatory reaction, fibrogenesis, vascular invasion, and tumor metastasis in various cell types. As an intracellular molecule, it is associated with LECT2-mediated amyloidosis, in which LECT2 misfolding results in insoluble fibrils in multiple tissues such as the kidney, liver, and lung. Recently, LECT2 was found to be associated with the development of rheumatoid arthritis and osteoarthritis, involving the dysregulation of osteoclasts, mesenchymal stem cells, osteoblasts, chondrocytes, and endothelial cells in the bone microenvironment. LECT2 is implicated in the development of cancers, such as hepatocellular carcinoma via MET-mediated PTP1B/Raf1/ERK signaling pathways and is proposed as a biomarker. The mechanisms by which LECT2 regulates diverse pathogenic conditions in various tissues remain to be fully elucidated. Further research to understand the role of LECT2 in a tissue tropism-dependent manner would facilitate the development of LECT2 as a biomarker for diagnosis and therapeutic target.

LECT2 Protects Nile Tilapia (Oreochromis niloticus) Against Streptococcus agalatiae Infection

Leukocyte cell-derived chemotaxin 2 (LECT2) is a multifunctional cytokine that especially plays an important role in innate immune. However, the roles of LECT2 in the immune response of the economically important fish Nile tilapia (Oreochromis niloticus) against bacterial infection remains unclear. In this study, a lect2 gene from Nile tilapia (On-lect2) was identified, and its roles in the fish’s immune response against bacterial infection were determined and characterised. On-lect2 contains an open reading frame of 456 bp that encodes a peptide of 151 amino acids, as well as the conservative peptidase M23 domain. On-LECT2 is 62%–84% identical to other fish species and about 50% identical to mammals. The highest transcriptional level of On-lect2 was detected in the liver, whereas the lowest levels were detected in the other tissues. Moreover, the On-LECT2 protein is located mainly in the brain and head kidney. The transcriptional levels of On-lect2 substantially increased in the head kidney, brain, liver and spleen after Streptococcus agalactiae infection. Knockdown On-lect2 led to higher mortality due to liver necrosis or haemorrhage and splenomegaly. In vitro analysis indicated that the recombinant protein of On-LECT2 improved phagocytic activity of head kidney-derived macrophages. In vivo challenge experiments revealed several functions of On-LECT2 in the immune response of Nile tilapia against bacterial infection, including promotion of inflammation, reduction of tissue damages and improvement of survival rate.

LECT2 as a hepatokine links liver steatosis to inflammation via activating tissue macrophages in NASH

It remains unclear how hepatic steatosis links to inflammation. Leukocyte cell-derived chemotaxin 2 (LECT2) is a hepatokine that senses fat in the liver and is upregulated prior to weight gain. The aim of this study was to investigate the significance of LECT2 in the development of nonalcoholic steatohepatitis (NASH). In human liver biopsy samples, elevated LECT2 mRNA levels were positively correlated with body mass index (BMI) and increased in patients who have steatosis and inflammation in the liver. LECT2 mRNA levels were also positively correlated with the mRNA levels of the inflammatory genes CCR2 and TLR4. In C57BL/6J mice fed with a high-fat diet, mRNA levels of the inflammatory cytokines Tnfa and Nos2 were significantly lower in Lect2 KO mice. In flow cytometry analyses, the number of M1-like macrophages and M1/M2 ratio were significantly lower in Lect2 KO mice than in WT mice. In KUP5, mouse kupffer cell line, LECT2 selectively enhanced the LPS-induced phosphorylation of JNK, but not that of ERK and p38. Consistently, LECT2 enhanced the LPS-induced phosphorylation of MKK4 and TAB2, upstream activators of JNK. Hepatic expression of LECT2 is upregulated in association with the inflammatory signature in human liver tissues. The elevation of LECT2 shifts liver residual macrophage to the M1-like phenotype, and contributes to the development of liver inflammation. These findings shed light on the hepatokine LECT2 as a potential therapeutic target that can dissociate liver steatosis from inflammation.

Transcriptional analysis and differentially expressed gene screening of spontaneous liver tumors in CBA/CaJ mice

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related deaths worldwide due to its frequent metastasis, tumor recurrence, and lack of curative treatment. However, the underlying molecular mechanisms involved in HCC progression remain unclear. Here, we analyzed the global gene expression of spontaneous liver tumor tissue from CBA/CaJ mice by RNA-Seq and identified 10,706 and 10,374 genes in the normal and liver tumor groups, respectively. Only 9793 genes were expressed in both, 913 genes were identified in only the liver tumor group, and 581 genes were found in normal liver tissues. There were 2054 differentially expressed genes (DEGs), with 975 down-regulated genes and 1079 up-regulated genes. Gene ontology (GO) term enrichment analysis showed that 43 up-regulated genes were significantly associated with cell cycle regulation and hundreds of up-regulated genes were related to cell migration, adhesion, or metabolic processes. KEGG pathway enrichment also demonstrated that some DEGs were tightly associated with the cell cycle, extracellular matrix (ECM)-receptor interactions, as well as protein digestion and absorption pathways, indicating that the activation of these oncogenic cascades was closely related to tumor liver progression in CBA/CaJ mice. Ninety-three genes with elevated expression levels preferentially localized in microtubules, kinetochores, and spindles play an important role during mitosis and meiosis and are associated with the reorganization of the cytoskeleton in cancer cells during migration and invasion. Some ECM-related genes were significantly different in the tumor group, including collagen types I, III, IV, V, and VI, non-collagenous glycoproteins, laminin, and fibronectin. We further validated the functions of upregulated genes, such as cyclin-dependent kinase 1 (CDK1) and polo-like kinase 1 (PLK1), with regards to cell cycle regulation, apoptosis, and proliferation in normal human liver or liver tumor-derived cell lines. Our results indicated that the cell cycle dysregulation, ECM-receptor interaction, and cytoskeleton-associated genes in mouse livers may promote HCC progression and deciphering the function of the genes will help investigators understand the underlying molecular mechanism of HCC.

LECT2, a Ligand for Tie1, Plays a Crucial Role in Liver Fibrogenesis

Liver fibrosis is a very common condition seen in millions of patients with various liver diseases, and yet no effective treatments are available owing to poorly characterized molecular pathogenesis. Here, we show that leukocyte cell-derived chemotaxin 2 (LECT2) is a functional ligand of Tie1, a poorly characterized endothelial cell (EC)-specific orphan receptor. Upon binding to Tie1, LECT2 interrupts Tie1/Tie2 heterodimerization, facilitates Tie2/Tie2 homodimerization, activates PPAR signaling, and inhibits the migration and tube formations of EC. In vivo studies showed that LECT2 overexpression inhibits portal angiogenesis, promotes sinusoid capillarization, and worsens fibrosis, whereas these changes were reversed in Lect2-KO mice. Adeno-associated viral vector serotype 9 (AAV9)-LECT2 small hairpin RNA (shRNA) treatment significantly attenuates fibrosis. Upregulation of LECT2 is associated with advanced human liver fibrosis staging. We concluded that targeting LECT2/Tie1 signaling may represent a potential therapeutic target for liver fibrosis, and serum LECT2 level may be a potential biomarker for the screening and diagnosis of liver fibrosis.

Transcriptional regulation of chicken leukocyte cell-derived chemotaxin 2 in response to toll-like receptor 3 stimulation

Objective

Leukocyte cell-derived chemotaxin 2 (LECT2) is associated with several physiological processes including inflammation, tumorigenesis, and natural killer T cell generation. Chicken LECT2 (chLECT2) gene was originally identified as one of the differentially expressed genes in chicken kidney tissue, where the chickens were fed with different calcium doses. In this study, the molecular characteristics and gene expression of chLECT2 were analyzed under the stimulation of toll-like receptor 3 (TLR3) ligand to understand the involvement of chLECT2 expression in chicken metabolic disorders.

Methods

Amino acid sequence of LECT2 proteins from various species including fowl, fish, and mammal were retrieved from the Ensembl database and subjected to Insilco analyses. In addition, the time- and dose-dependent expression of chLECT2 was examined in DF-1 cells which were stimulated with polyinosinic:polycytidylic acid (poly [I:C]), a TLR3 ligand. Further, to explore the transcription factors required for the transcription of chLECT2, DF-1 cells were treated with poly (I:C) in the presence or absence of the nuclear factor κB (NFκB) and activated protein 1 (AP-1) inhibitors.

Results

The amino acid sequence prediction of chLECT2 protein revealed that along with duck LECT2 (duLECT2), it has unique signal peptide different from other vertebrate orthologs, and only chLECT2 and duLECT2 have an additional 157 and 161 amino acids on their carboxyl terminus, respectively. Phylogenetic analysis suggested that chLECT2 is evolved from a common ancestor along with the actinopterygii hence, more closely related than to the mammals. Our quantitative polymerase chain reaction results showed that, the expression of chLECT2 was up-regulated significantly in DF-1 cells under the stimulation of poly (I:C) (p<0.05). However, in the presence of NFκB or AP-1 inhibitors, the expression of chLECT2 is suppressed suggesting that both NFκB and AP-1 transcription factors are required for the induction of chLECT2 expression.

Conclusion

The present results suggest that chLECT2 gene might be a target gene of TLR3 signaling. For the future, the expression pattern or molecular mechanism of chLECT2 under stimulation of other innate immune receptors shall be studied. The protein function of chLECT2 will be more clearly understood if further investigation about the mechanism of LECT2 in TLR pathways is conducted.

Lect2 Controls Inflammatory Monocytes to Constrain the Growth and Progression of Hepatocellular Carcinoma

Leukocyte cell-derived chemotaxin-2 (LECT2) was originally identified as a hepatocyte-secreted chemokine-like factor and a positive target of β-catenin signaling. Here, we dissected out the mechanisms by which LECT2 modulates hepatocellular carcinoma (HCC) development using both HCC mouse models and human HCC samples. We have demonstrated that LECT2 exhibits dual abilities as it has profound repercussions on the tumor phenotype itself and the immune microenvironment. Its absence confers Ctnnb-1-mutated tumor hepatocytes a stronger ability to undergo epithelial to mesenchymal transition and fosters the accumulation of pejorative inflammatory monocytes harboring immunosuppressive properties and strong tumor-promoting potential. Consistent with our HCC mouse model, a low level of LECT2 in human HCC is strongly associated with high tumor grade and the presence of inflammatory infiltrates, emphasizing the clinical value of LECT2 in human liver tumorigenesis. Conclusion: Our findings have demonstrated that LECT2 is a key player in liver tumorigenesis because its absence reshapes the tumor microenvironment and the tumor phenotype, revealing LECT2 as a promising immunotherapeutic option for HCC.

Lect2 deficiency is characterised by altered cytokine levels and promotion of intestinal tumourigenesis

Leukocyte cell-derived chemotaxin 2 (Lect2) is a chemokine-like chemotactic factor that has been identified as a downstream target of the Wnt signalling pathway. Whilst the primary function of Lect2 is thought to be in modulating the inflammatory process, it has recently been implicated as a potential inhibitor of the Wnt pathway. Deregulation of the Wnt pathway, often due to loss of the negative regulator APC, is found in ~80% of colorectal cancer (CRC). Here we have used the ApcMin/+Lect2-/- mouse model to characterise the role of Lect2 in Wnt-driven intestinal tumourigenesis. Histopathological, immunohistochemical, PCR and flow cytometry analysis were employed to identify the role of Lect2 in the intestine. The ApcMin/+Lect2-/- mice had a reduced mean survival and a significantly increased number of adenomas in the small intestine with increased severity. Analysis of Lect2 loss indicated it had no effect on the Wnt pathway in the intestine but significant differences were observed in circulating inflammatory markers, CD4+ T cells, and T cell lineage-specification factors. In summary, in the murine intestine loss of Lect2 promotes the initiation and progression of Wnt-driven colorectal cancer. This protection is performed independently of the Wnt signalling pathway and is associated with an altered inflammatory environment during Wnt-driven tumorigenesis.

Circulating LECT2 levels in newly diagnosed type 2 diabetes mellitus and their association with metabolic parameters: An observational study

Leukocyte cell-derived chemotaxin 2 (LECT2) is a hepatokine expressed in hepatocytes and appears to be involved in energy metabolism. The aim of this study was to determine plasma LECT2 levels in newly diagnosed type 2 diabetic patients and to correlate the results with various metabolic parameters.A total of 93 newly diagnosed type 2 diabetic patients and 80 age- and sex-matched nondiabetes mellitus ones were enrolled in the study. Plasma LECT2 levels were measured by enzyme-linked immunosorbent assay.Circulating LECT2 levels were approximately 1.3 times higher in newly diagnosed type 2 diabetic patients than in controls (mean 30.30 vs 23.23 ng/mL, P < .001). Correlation analysis showed that LECT2 was negatively associated with high-density lipoprotein-cholesterol (HDL-C) levels in type 2 diabetic patients and obese subjects (P < .05). In multiple stepwise regression analysis, HDL-C, HOMA-IR, BMI, FINS, and TG were significantly independent determinants for LECT2 (P < .05).Our study showed that circulating LECT2 concentrations are significantly higher in newly diagnosed type 2 diabetic patients and further elevated in obese type 2 diabetic patients. LECT2 concentrations are significantly negatively associated with HDL-cholesterol levels in newly diagnosed type 2 diabetic patients and obese subjects.

Characterization of the LECT2 gene and its protective effects against microbial infection via large lymphocytes in Lampetra japonica

Leukocyte cell-derived chemotaxin 2 (LECT2) is a multifunctional protein of the innate immune system that defends against bacterial infections and chemotactic activity. However, its precise function in lamprey remains unclear. In this study, a novel LECT2 gene was first cloned from Lampetra japonica. The full-length cDNA sequence of L-LECT2 consists of a 606-bp ORF encoding a protein of 201 amino acid residues. L-LECT2 has greater than 50% sequence identity with its homologs in jawed vertebrates. FACS and immunohistochemistry assays were used to determine that the L-LECT2 protein was primarily distributed in the intestines and supraneural body tissues of lamprey, also marginally detectable in leukocytes. However, the expression of L-LECT2 was differentially upregulated in the intestines and heart after treatment with LPS. The recombinant L-LECT2 resulted in significant promoting migration of the leukocytes in vitro. Our data demonstrate that L-LECT2 treatment could enhance phagocytosis in lamprey large lymphocytes. Thus, our results suggest that LECT2 can modulate the host defense in lamprey and mediate antibacterial protection against E.coli through large lymphocytes.

Alleviation of lipopolysaccharide/d-galactosamine-induced liver injury in leukocyte cell-derived chemotaxin 2 deficient mice

Leukocyte cell-derived chemotaxin 2 (LECT2) is a secreted pleiotropic protein that is mainly produced by the liver. We have previously shown that LECT2 plays an important role in the pathogenesis of inflammatory liver diseases. Lipopolysaccharide/d-galactosamine (LPS/d-GalN)-induced acute liver injury is a known animal model of fulminant hepatic failure. Here we found that this hepatic injury was alleviated in LECT2-deficient mice. The levels of TNF-α and IFN-γ, which mediate this hepatitis, had significantly decreased in these mice, with the decrease in IFN-γ production notably greater than that in TNF-α. We therefore analyzed IFN-γ-producing cells in liver mononuclear cells. Flow cytometric analysis showed significantly reduced IFN-γ production in hepatic NK and NKT cells in LECT2-deficient mice compared with in wild-type mice. We also demonstrated a decrease in IFN-γ production in LECT2-deficient mice after systemic administration of recombinant IL-12, which is known to induce IFN-γ in NK and NKT cells. These results indicate that a decrease of IFN-γ production in NK and NKT cells was involved in the alleviation of LPS/d-GalN-induced liver injury in LECT2-deficient mice.

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LECT2-deficient mice are less sensitive to LPS/d-GalN-induced hepatitis.

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The IFN-γ level in hepatic NK and NKT cells is lower in LECT2-deficient mice.

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IL-12-induced IFN-γ production is diminished in LECT2-deficient mice.

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The pathological role of LECT2 in hepatitis could depend on the initiation of immune response cells.

Amyloidosis: Insights from Proteomics

Amyloidoses are a spectrum of disorders caused by abnormal folding and extracellular deposition of proteins. The deposits lead to tissue damage and organ dysfunction, particularly in the heart, kidneys, and nerves. There are at least 30 different proteins that can cause amyloidosis. The clinical management depends entirely on the type of protein deposited, and thus on the underlying pathogenesis, and often requires high-risk therapeutic intervention. Application of mass spectrometry-based proteomic technologies for analysis of amyloid plaques has transformed the way amyloidosis is diagnosed and classified. Proteomic assays have been extensively used for clinical management of patients with amyloidosis, providing unprecedented diagnostic and biological information. They have shed light on the pathogenesis of different amyloid types and have led to identification of numerous new amyloid types, including ALECT2 amyloidosis, which is now recognized as one of the most common causes of systemic amyloidosis in North America.

Reduced serum level of leukocyte cell-derived chemotaxin 2 is associated with the presence of diabetic retinopathy

BACKGROUND

Vascular endothelial growth factor (VEGF) signaling is an important pathway in the development of diabetic retinopathy (DR). A recent report showed that leukocyte cell-derived chemotaxin 2 (LECT2) suppresses the VEGF signaling in endothelial cells. However, the clinical relevance of LECT2 in DR is unknown. This study aimed to investigate serum LECT2 levels and the presence of DR.

METHODS

The study included 230 people with type 2 diabetes mellitus (DM), 95 with DR and 135 without DR. Serum LECT2 levels were measured using an enzyme-linked immunosorbent assay. Data were evaluated using Spearman's rank correlation, univariate and multivariate logistic regression.

RESULTS

Serum LECT2 levels were significantly lower in participants with DM having DR than in those not having DR (35.6±14.9ng/ml vs. 44.5±17.6ng/ml, P<0.001). Spearman's rank correlation analysis revealed a significant association between serum LECT2 levels and the presence of DR (P<0.001). Multiple regression analysis revealed that serum LECT2 levels were independently related to DR (P<0.001).

CONCLUSIONS

These findings indicated that serum LECT2 level is negatively associated with the presence of DR and suggest that low circulating LECT2 level is a risk factor for DR.

LECT2 drives haematopoietic stem cell expansion and mobilization via regulating the macrophages and osteolineage cells

Haematopoietic stem cells (HSCs) can differentiate into cells of all lineages in the blood. However, the mechanisms by which cytokines in the blood affect HSC homeostasis remain largely unknown. Here we show that leukocyte cell-derived chemotaxin 2 (LECT2), a multifunctional cytokine, induces HSC expansion and mobilization. Recombinant LECT2 administration results in HSC expansion in the bone marrow and mobilization to the blood via CD209a. The effect of LECT2 on HSCs is reduced after specific depletion of macrophages or reduction of osteolineage cells. LECT2 treatment reduces the tumour necrosis factor (TNF) expression in macrophages and osteolineage cells. In TNF knockout mice, the effect of LECT2 on HSCs is reduced. Moreover, LECT2 induces HSC mobilization in irradiated mice, while granulocyte colony-stimulating factor does not. Our results illustrate that LECT2 is an extramedullar cytokine that contributes to HSC homeostasis and may be useful to induce HSC mobilization.

Inhibition of VEGF165/VEGFR2-dependent signaling by LECT2 suppresses hepatocellular carcinoma angiogenesis

Hepatocellular carcinoma (HCC) relies on angiogenesis for growth and metastasis. Leukocyte cell-derived chemotaxin 2 (LECT2) is a cytokine and preferentially expressed in the liver. Previous studies have found that LECT2 targets to both immune and tumor cells to suppress HCC development and vascular invasion. Although LECT2 did not affect HCC cells growth in vitro, it still suppressed HCC xenografts growth in immune-deficient mice, suggesting other cells such as stroma cells may also be targeted by LECT2. Here, we sought to determine the role of LECT2 in tumor angiogenesis in HCC patients. We found that LECT2 expression inhibited tumor growth via angiogenesis in the HCC xenograft model. Specifically, we demonstrated that recombinant human LECT2 protein selectively suppressed vascular endothelial growth factor (VEGF)₁₆₅-induced endothelial cell proliferation, migration, and tube formation in vitro and in vivo. Mechanistically, LECT2 reduced VEGF receptor 2 tyrosine phosphorylation and its downstream extracellular signal-regulated kinase and AKT phosphorylation. Furthermore, LECT2 gene expression correlated negatively with angiogenesis in HCC patients. Taken together, our findings demonstrate that LECT2 inhibits VEGF₁₆₅-induced HCC angiogenesis through directly binding to VEGFR2 and has broad applications in treating VEGF-mediated solid tumors.

Crystal Structure of Human Leukocyte Cell-derived Chemotaxin 2 (LECT2) Reveals a Mechanistic Basis of Functional Evolution in a Mammalian Protein with an M23 Metalloendopeptidase Fold

Human leukocyte cell-derived chemotaxin 2 (LECT2), which is predominantly expressed in the liver, is a multifunctional protein. LECT2 is becoming a potential therapeutic target for several diseases of worldwide concern such as rheumatoid arthritis, hepatocellular carcinoma, and obesity. Here, we present the crystal structure of LECT2, the first mammalian protein whose structure contains an M23 metalloendopeptidase fold. The LECT2 structure adopts a conserved Zn(II) coordination configuration but lacks a proposed catalytic histidine residue, and its potential substrate-binding groove is blocked in the vicinity of the Zn(II)-binding site by an additional intrachain loop at the N terminus. Consistent with these structural features, LECT2 was found to be catalytically inactive as a metalloendopeptidase against various types of peptide sequences, including pentaglycine. In addition, a surface plasmon resonance analysis demonstrated that LECT2 bound to the c-Met receptor with micromolar affinity. These results indicate that LECT2 likely plays its critical roles by acting as a ligand for the corresponding protein receptors rather than as an enzymatically active peptidase. The intrachain loop together with the pseudo-active site groove in LECT2 structure may be specific for interactions between LECT2 and receptors. Our study reveals a mechanistic basis for the functional evolution of a mammalian protein with an M23 metalloendopeptidase fold and potentially broadens the implications for the biological importance of noncatalytic peptidases in the M23 family.

Leukocyte Cell-Derived Chemotaxin 2-Associated Amyloidosis: A Recently Recognized Disease with Distinct Clinicopathologic Characteristics

Amyloidosis derived from leukocyte cell-derived chemotaxin 2 is a recently recognized form of amyloidosis, and it has already been established as a frequent form of systemic amyloidosis in the United States, with predominant involvement of kidney and liver. The disease has a strong ethnic bias, affecting mainly Hispanics (particularly Mexicans). Additional ethnic groups prone to develop amyloidosis derived from leukocyte cell-derived chemotaxin 2 include Punjabis, First Nations people in British Columbia, and Native Americans. Most patients are elderly who present with chronic renal insufficiency and bland urinary sediment. Proteinuria is variable, being absent altogether in about one third of patients. Liver involvement is frequently an incidental finding. Amyloidosis derived from leukocyte cell-derived chemotaxin 2 deposits shows a characteristic distribution: in the kidney, there is consistent involvement of cortical interstitium, whereas in the liver, there is a preferential involvement of periportal and pericentral vein regions. Concurrent renal disease is frequent, with diabetic nephropathy and IgA nephropathy being the most common. Patient survival is excellent, likely because of the rarity of cardiac involvement, whereas renal survival is guarded, with a median renal survival of 62 months in those without concurrent renal disease. There is currently no efficacious therapy for amyloidosis derived from leukocyte cell-derived chemotaxin 2 amyloidosis. Renal transplantation seems to be a reasonable treatment for patients with advanced renal failure, although the disease may recur in the allograft. The pathogenesis of amyloidosis derived from leukocyte cell-derived chemotaxin 2 amyloidosis has not yet been elucidated. It could be a result of leukocyte cell-derived chemotaxin 2 overexpression by hepatocytes either constitutively (controlled by yet-uncharacterized genetic defects) or secondary to hepatocellular damage. It is critical not to misdiagnose amyloidosis derived from leukocyte cell-derived chemotaxin 2 amyloidosis as Ig light chain-derived amyloidosis to avoid harmful chemotherapy.

Leukocyte cell-derived chemotaxin 2 antagonizes MET receptor activation to suppress hepatocellular carcinoma vascular invasion by protein tyrosine phosphatase 1B recruitment

Leukocyte cell-derived chemotoxin 2 (LECT2) has been shown to act as a tumor suppressor in hepatocellular carcinoma (HCC). However, the underlying mechanism has not yet been completely defined. Here, we employ a LECT2-affinity column plus liquid chromatography coupled with tandem mass spectrometry to identify LECT2-binding proteins and found that MET receptor strongly interacted with LECT2 protein. Despite the presence of hepatocyte growth factor, the LECT2 binding causes an antagonistic effect to MET receptor activation through recruitment of protein tyrosine phosphatase 1B. The antagonistic effect of LECT2 on MET activation also mainly contributes to the blockage of vascular invasion and metastasis of HCC. Furthermore, serial deletions and mutations of LECT2 showed that the HxGxD motif is primarily responsible for MET receptor binding and its antagonistic effects.

CONCLUSION

These findings reveal a novel, specific inhibitory function of LECT2 in HCC by the direct binding and inactivation of MET, opening a potential avenue for treating MET-related liver cancer.

iTRAQ-based proteomics reveals novel biomarkers of osteoarthritis

Objective:

We performed comprehensive proteomic analyses of articular cartilage by using the isobaric tags for relative and absolute quantitation (iTRAQ) method, and searched for candidate biomarkers for osteoarthritis (OA).

Methods:

Articular cartilage was collected from patients with OA or femoral neck fracture for the control group. Molecular variations were detected by the iTRAQ method, and quantitative analyses were performed by western blot.

Results:

Using the iTRAQ method, we identified 76 proteins with different expression levels in OA patients and the control group. Among these proteins, we selected LECT2 (leukocyte cell-derived chemotaxin-2), BAALC (brain and acute leukemia, cytoplasmic), and PRDX6 (peroxiredoxin-6), which had not been reported as biomarkers for OA.

Conclusions:

Use of these proteins in combination with conventional OA biomarkers may better reflect the grade and prognosis of OA.

Crystallization and preliminary X-ray analysis of human leukocyte cell-derived chemotaxin 2 (LECT2)

Human leukocyte cell-derived chemotaxin 2 (LECT2) is a chemotactic factor for neutrophils that plays multifunctional roles in liver regeneration, regulation of neuritic development and proliferation of chondrocytes and osteoblasts. In addition, the C-terminal region of LECT2 belongs to the zinc metalloendopeptidase M23 (PF01551) family. Purified LECT2 was crystallized using the sitting-drop vapour-diffusion method at 293 K. Crystals of selenomethionine-substituted LECT2 that diffracted X-rays to 1.94 Å resolution were obtained using a reservoir solution consisting of 0.2 M ammonium sulfate, 0.1 M HEPES pH 7.5, 25%(w/v) PEG 8000. The crystal belonged to space group P2₁2₁2₁, with unit-cell parameters a=59.4, b=63.5, c=64.0 Å. The calculated Matthews coefficient (VM=2.10 Å3 Da(-1), solvent content 40%) indicates that the crystal consists of two molecules per asymmetric unit.

LECT2 protects mice against bacterial sepsis by activating macrophages via the CD209a receptor

Leukocyte cell–derived chemotaxin 2 enhances phagocytosis and bacterial killing of macrophages to improve the outcome of bacterial-induced sepsis.

Leukocyte cell–derived chemotaxin 2 (LECT2) is a multifunctional cytokine and reduced plasma levels were found in patients with sepsis. However, precise functions and mechanisms of LECT2 remain unclear. The aim of the present study was to determine the role of LECT2 in modulating immune responses using mouse sepsis models. We found that LECT2 treatment improved outcome in mice with bacterial sepsis. Macrophages (MΦ), but not polymorphonuclear neutrophils, mediated the beneficial effect of LECT2 on bacterial sepsis. LECT2 treatment could alter gene expression and enhance phagocytosis and bacterial killing of MΦ in vitro. CD209a was identified to specifically interact with LECT2 and mediate LECT2-induced MΦ activation. CD209a-expressing MΦ was further confirmed to mediate the effect of LECT2 on sepsis in vivo. Our data demonstrate that LECT2 improves protective immunity in bacterial sepsis, possibly as a result of enhanced MΦ functions via the CD209a receptor. The modulation of MΦ functions by LECT2 may serve as a novel potential treatment for sepsis.

Oncogenic β-catenin triggers an inflammatory response that determines the aggressiveness of hepatocellular carcinoma in mice

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Its pathogenesis is frequently linked to liver inflammation. Gain-of-function mutations in the gene encoding β-catenin are frequent genetic modifications found in human HCCs. Thus, we investigated whether inflammation was a component of β-catenin-induced tumorigenesis using genetically modified mouse models that recapitulated the stages of initiation and progression of this tumoral process. Oncogenic β-catenin signaling was found to induce an inflammatory program in hepatocytes that involved direct transcriptional control by β-catenin and activation of the NF-κB pathway. This led to a specific inflammatory response, the intensity of which determined the degree of tumor aggressiveness. The chemokine-like chemotactic factor leukocyte cell-derived chemotaxin 2 (LECT2) and invariant NKT (iNKT) cells were identified as key interconnected effectors of liver β-catenin-induced inflammation. In genetic deletion models lacking the gene encoding LECT2 or iNKT cells, hepatic β-catenin signaling triggered the formation of highly malignant HCCs with lung metastasis. Thus, our results identify inflammation as a key player in β-catenin-induced liver tumorigenesis. We provide strong evidence that, by activating pro- and antiinflammatory mediators, β-catenin signaling produces an inflammatory microenvironment that has an impact on tumoral development. Our data are consistent with the fact that most β-catenin-activated HCCs are of better prognosis.