ANGPTL2 promotes tumor metastasis in hepatocellular carcinoma

The Two Faces of Angiopoietin-Like Protein 2 in Cancer

The tumor microenvironment is composed of tumor cells and various stromal cell types, such as immune cells, fibroblasts, and vascular cells. Signaling interactions between tumor and stromal cells orchestrate the tumor microenvironment's contribution to tumor progression. Angiopoietin-like protein 2 (ANGPTL2) is a secreted glycoprotein homologous to angiopoietins. Previous studies indicate that tumor cell-derived ANGPTL2 serves as a tumor promoter. However, recent studies suggest that tumor stroma-derived ANGPTL2 shows tumor-suppressive activity by enhancing anti-tumor immune responses, supporting a dual function for ANGPTL2 in cancer pathology. Such complexity can complicate development of effective therapeutic strategies targeting ANGPTL2. In this Review, we focus on ANGPTL2 activity in the tumor microenvironment and its function in anti-cancer immunity.

Periodontitis promotes hepatocellular carcinoma in Stelic Animal model (STAM) mice

Periodontitis is a prevalent oral inflammatory disease that leads to alveolar bone loss and may exert an adverse impact on systemic health. Periodontal disease may be associated with hepatocellular carcinoma (HCC); however, the mechanism of such an association is unknown. In this study, Stelic Animal model (STAM) mice, a model of nonalcoholic steatohepatitis (NASH)-HCC, were induced to develop periodontitis and subjected to histopathological and immunological analyses. HCC progression was greater in STAM mice with experimental periodontitis compared with that in STAM mice without experimental periodontitis. Tumor necrosis factor-α (TNFα), matrix metalloproteinase-9 (MMP9), collagen 1, and angiopoietin-like protein 2 (ANGPTL2) gene expression was significantly increased in the liver of the periodontitis group. ANGPTL2 was previously reported to be involved in the pathogenesis of periodontitis, and HCC and ANGPTL2 protein tended to be more abundant in the pocket epithelium of STAM mice with experimental periodontitis than in control STAM mice. ANGPTL2 levels in the serum of STAM mice with experimental periodontitis tended to be higher than in control STAM mice. Our results indicate that ANGPTL2 is produced in chronically inflamed periodontal tissue and then travels to the liver via the bloodstream where it accumulates to promote the progression of hepatocellular carcinoma.

Role of the angiopoietin-like protein family in the progression of NAFLD

Non-alcoholic fatty liver disease (NAFLD) is the most frequent cause of chronic liver disease, with a range of conditions including non-alcoholic fatty liver, non-alcoholic steatohepatitis, cirrhosis, and hepatocellular carcinoma (HCC). Currently recognized as the liver component of the metabolic syndrome, NAFLD is intimately linked to metabolic diseases. Angiopoietin-like proteins (ANGPTLs) comprise a class of proteins that resemble angiopoietins structurally. It is closely related to obesity, insulin resistance and lipid metabolism, and may be the critical factor of metabolic syndrome. In recent years, many studies have found that there is a certain correlation between ANGPTLs and the occurrence and progression of NAFLD disease spectrum. This article reviews the possible mechanisms and roles of ANGPTL protein in the pathogenesis and progression of NAFLD.

ANGPTL2+cancer-associated fibroblasts and SPP1+macrophages are metastasis accelerators of colorectal cancer

Background

Liver metastasis (LM) is a leading cause of cancer-related deaths in CRC patients, whereas the associated mechanisms have not yet been fully elucidated. Therefore, it is urgently needed to deeply explore novel metastasis accelerators and therapeutic targets of LM-CRC.

Methods

The bulk RNA sequencing data and clinicopathological information of CRC patients were enrolled from the TCGA and GEO databases. The single-cell RNA sequencing (scRNA-seq) datasets of CRC were collected from and analyzed in the Tumor Immune Single-cell Hub (TISCH) database. The infiltration levels of cancer-associated fibroblasts (CAFs) and macrophages in CRC tissues were estimated by multiple immune deconvolution algorithms. The prognostic values of genes were identified by the Kaplan-Meier curve with a log-rank test. GSEA analysis was carried out to annotate the significantly enriched gene sets. The biological functions of cells were experimentally verified.

Results

In the present study, hundreds of differentially expressed genes (DEGs) were selected in LM-CRC compared to primary CRC, and these DEGs were significantly associated with the regulation of endopeptidase activity, blood coagulation, and metabolic processes. Then, SPP1, CAV1, ANGPTL2, and COLEC11 were identified as the characteristic DEGs of LM-CRC, and higher expression levels of SPP1 and ANGPTL2 were significantly associated with worse clinical outcomes of CRC patients. In addition, ANGPTL2 and SPP1 mainly distributed in the tumor microenvironment (TME) of CRC tissues. Subsequent scRNA-seq analysis demonstrated that ANGPTL2 and SPP1 were markedly enriched in the CAFs and macrophages of CRC tissues, respectively. Moreover, we identified the significantly enriched gene sets in LM-CRC, especially those in the SPP1+macrophages and ANGPTL2+CAFs, such as the HALLMARK_EPITHELIAL_MESENCHYMAL_TRANSITION and the HALLMARK_COMPLEMENT. Finally, our in vitro experiments proved that ANGPTL2+CAFs and SPP1+macrophages promote the metastasis of CRC cells.

Conclusion

Our study selected four characteristic genes of LM-CRC and identified ANGPTL2+CAFs and SPP1+macrophages subtypes as metastasis accelerators of CRC which provided a potential therapeutic target for LM-CRC.

Synaptotagmin 11 scaffolds MKK7-JNK signaling process to promote stem-like molecular subtype gastric cancer oncogenesis

Background

Identifying biomarkers related to the diagnosis and treatment of gastric cancer (GC) has not made significant progress due to the heterogeneity of tumors. Genes involved in histological classification and genetic correlation studies are essential to develop an appropriate treatment for GC.

Methods

In vitro and in vivo lentiviral shRNA library screening was performed. The expression of Synaptotagmin (SYT11) in the tumor tissues of patients with GC was confirmed by performing Immunohistochemistry, and the correlation between the expression level and the patient’s survival rate was analyzed. Phospho-kinase array was performed to detect Jun N-terminal kinase (JNK) phosphorylation. SYT11, JNK, and MKK7 complex formation was confirmed by western blot and immunoprecipitation assays. We studied the effects of SYT11 on GC proliferation and metastasis, real-time cell image analysis, adhesion assay, invasion assay, spheroid formation, mouse xenograft assay, and liver metastasis.

Results

SYT11 is highly expressed in the stem-like molecular subtype of GC in transcriptome analysis of 527 patients with GC. Moreover, SYT11 is a potential prognostic biomarker for histologically classified diffuse-type GC. SYT11 functions as a scaffold protein, binding both MKK7 and JNK1 signaling molecules that play a role in JNK1 phosphorylation. In turn, JNK activation leads to a signaling cascade resulting in cJun activation and expression of downstream genes angiopoietin-like 2 (ANGPTL2), thrombospondin 4 (THBS4), Vimentin, and junctional adhesion molecule 3 (JAM3), which play a role in epithelial-mesenchymal transition (EMT). SNU484 cells infected with SYT11 shRNA (shSYT11) exhibited reduced spheroid formation, mouse tumor formation, and liver metastasis, suggesting a pro-oncogenic role of SYT11. Furthermore, SYT11-antisense oligonucleotide (ASO) displayed antitumor activity in our mouse xenograft model and was conferred an anti-proliferative effect in SNU484 and MKN1 cells.

Conclusion

SYT11 could be a potential therapeutic target as well as a prognostic biomarker in patients with diffuse-type GC, and SYT11-ASO could be used in therapeutic agent development for stem-like molecular subtype diffuse GC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02420-3.

Identification of Feature Genes of a Novel Neural Network Model for Bladder Cancer

Background: The combination of deep learning methods and oncogenomics can provide an effective diagnostic method for malignant tumors; thus, we attempted to construct a reliable artificial neural network model as a novel diagnostic tool for Bladder cancer (BLCA). Methods: Three expression profiling datasets (GSE61615, GSE65635, and GSE100926) were downloaded from the Gene Expression Omnibus (GEO) database. GSE61615 and GSE65635 were taken as the train group, while GSE100926 was set as the test group. Differentially expressed genes (DEGs) were filtered out based on the logFC and FDR values. We also performed Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses to explore the biological functions of the DEGs. Consequently, we utilized a random forest algorithm to identify feature genes and further constructed a neural network model. The test group was given the same procedures to validate the reliability of the model. We also explored immune cells' infiltration degree and correlation coefficients through the CiberSort algorithm and corrplot R package. The qRT-PCR assay was implemented to examine the expression level of the feature genes in vitro. Results: A total of 265 DEGs were filtered out and significantly enriched in muscle system processes, collagen-containing and focal adhesion signaling pathways. Based on the random forest algorithm, we selected 14 feature genes to construct the neural network model. The area under the curve (AUC) of the training group was 0.950 (95% CI: 0.850-1.000), and the AUC of the test group was 0.667 (95% CI: 0.333-1.000). Besides, we observed significant differences in the content of immune infiltrating cells and the expression levels of the feature genes. Conclusion: After repeated verification, our neural network model had clinical feasibility to identify bladder cancer patients and provided a potential target to improve the management of BLCA.

The Role of ANGPTL Gene Family Members in Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is highly aggressive with a poor prognosis and survival rate. Certain ANGPTL members have been implicated in tumor progression. However, the relevance of the ANGPTL gene family to HCC remains poorly understood. In this study, we explored the role of ANGPTLs in the prognosis of HCC.

Methods

From the CCLE database, we studied the expression of ANGPTLs in a range of cancer cell lines. The UCSC, HCCDB, and Human Protein Atlas databases were used to analyze the differences in mRNA and protein expression of ANGPTLs in HCC tissues. Additionally, the correlation between ANGPTL mRNA and methylation levels and clinicopathological features were assessed in the TCGA database. The correlation between ANGPTL mRNA and overall survival was determined by the Kaplan-Meier plotter. cBioPortal database was used to analyze ANGPTL genomic alterations. Genes associated with ANGPTLs were determined by enrichment with KEGG. Moreover, the differentially expressed genes of ANGPTLs were analyzed by the LinkedOmics database, and the KEGG pathway and miRNA targets of ANGPTLs were also enriched.

Results

There was a significant correlation between the ANGPTL members (excluding ANGPTL2) and the prognosis of HCC patients according to the Kaplan-Meier plotter analysis (p < 0.05). ANGPTL1 was the gene with the highest mutation frequency. ANGPTLs are involved in certain pathways that may influence the development of HCC.

Conclusion

In summary, the expression of some members of ANGPTLs was significantly correlated with HCC prognosis, suggesting that the ANGPTL gene family members may be promising molecular markers for HCC treatment and prognosis.

Relationship between miR-204 and ANGPTL2 expression and diagnosis, pathological stage, and prognosis in patients with colon cancer

Background

Angiopoietin-like protein 2 (ANGPTL2) is linked to various tumors. MicroRNA-204 (miR-204) is associated with colorectal cancer (CRC). Bioinformatic analysis has demonstrated a targeting relationship between miR-204 and ANGPTL2. The present study aimed to investigate the role of miR-204 in the proliferation and apoptosis of colorectal tumor cells.

Methods

Colorectal tumor tissues were collected. Normal colon mucosa was used as a control. The relationship between miR-204 and ANGPTL2 expression and tumor stage and prognosis was analyzed. The dual-luciferase reporter assay confirmed targeted regulation between miR-204 and ANGPTL2. SW480 cells were allocated to the miR-NC group and the miR-204 mimic group, followed by apoptotic analysis using flow cytometry and cellular proliferation analysis using EdU staining.

Results

Compared with normal colonic mucosa, miR-204 expression was decreased in colorectal tumor tissues and ANGPTL2 expression was increased, which correlated with TNM staging. The prognosis of patients with low miR-204 expression and high ANGPTL2 expression was worse than for patients with high miR-204 expression and low ANGPTL2 expression. The dual-luciferase reporter assay confirmed a targeting regulation relationship between miR-204 and ANGPTL2. Transfection of miR-204 mimic significantly inhibited the expression of ANGPTL2 and cell proliferation in SW480 cells and promoted apoptosis.

Conclusions

Downregulating miR-204 expression plays a vital role in upregulating ANGPTL2 expression and promoting the pathogenesis of CRC. MiR-204 is able to hinder the proliferation of colorectal tumor cells and encourage apoptosis by targeting the inhibition of ANGPTL2 expression.

Hepatocellular Carcinoma: Molecular Pathogenesis and Therapeutic Advances

Hepatocellular carcinoma (HCC), the most common form of liver cancer, continues to be a serious medical problem with poor prognosis, without major therapeutic improvement for years and increasing incidence. Fortunately, advances in systemic treatment options are finally arriving for HCC patients. After a decade of sorafenib as a standard therapy for advanced HCC, several tyrosine kinase inhibitors (TKIs), antiangiogenic antibodies, and immune checkpoint inhibitors have reached the clinic. Although infections by hepatitis B virus and hepatitis C virus remain principal factors for HCC development, the rise of non- alcoholic steatohepatitis from diabetes mellitus or metabolic syndrome is impeding HCC decline. Knowledge of specific molecular mechanisms, based on the etiology and the HCC microenvironment that influence tumor growth and immune control, will be crucial for physician decision-making among a variety of drugs to prescribe. In addition, markers of treatment efficacy are needed to speed the movement of patients towards other potentially effective treatments. Consequently, research to provide scientific data for the evidence-based management of liver cancer is guaranteed in the coming years and discussed here.

Plasma angiopoietin-like protein 2 levels and mortality risk among younger-old Japanese people: a population-based case-cohort study

Aging is important medical and social problem. Excessive angiopoietin-like protein (ANGPTL)-2 signaling causes chronic tissue inflammation, promoting development and progression of aging-related diseases. Moreover, circulating ANGPTL2 levels reportedly predict risk of some aging-related diseases and subsequent death. However, there are as yet no reports of whether circulating ANGPTL2 levels predict vital prognosis in younger-old, community-dwelling populations. This study investigated associations between plasma ANGPTL2 levels and all-cause and specific-cause mortality in this population. The case-cohort study was abstracted from an on-going, age-specific prospective cohort study: the New Integrated Suburban Seniority Investigation Project. This project enrolled 3073 participants aged 64 years at the beginning of the investigation from 1996 through 2005. A sub-cohort of 714 randomly sampled participants plus 387 cases representing deceased participants followed through 2015 underwent survival analysis. Plasma ANGPTL2 concentrations were positively associated with >80% and 100% higher risk of all-cause mortality and cancer mortality, respectively, after adjustment for gender, smoking, alcohol consumption, walking time, sleep duration, caloric intake, medical status, disease history, BMI, and triglyceride, creatinine, uric acid, and high sensitivity C-reactive protein levels. More robust association between ANGPTL2 levels and all-cause and cancer mortality was seen in subjects with either frailties or with lifestyles of heavier drinking or current smoking. Elevated plasma ANGPTL2 levels are associated with high all-cause and cancer mortality in a community-dwelling sample of younger-old adults. These findings expand our knowledge of human aging and associated diseases.

Angptl2 is a Marker of Cellular Senescence: The Physiological and Pathophysiological Impact of Angptl2-Related Senescence

Cellular senescence is a cell fate primarily induced by DNA damage, characterized by irreversible growth arrest in an attempt to stop the damage. Senescence is a cellular response to a stressor and is observed with aging, but also during wound healing and in embryogenic developmental processes. Senescent cells are metabolically active and secrete a multitude of molecules gathered in the senescence-associated secretory phenotype (SASP). The SASP includes inflammatory cytokines, chemokines, growth factors and metalloproteinases, with autocrine and paracrine activities. Among hundreds of molecules, angiopoietin-like 2 (angptl2) is an interesting, although understudied, SASP member identified in various types of senescent cells. Angptl2 is a circulatory protein, and plasma angptl2 levels increase with age and with various chronic inflammatory diseases such as cancer, atherosclerosis, diabetes, heart failure and a multitude of age-related diseases. In this review, we will examine in which context angptl2 was identified as a SASP factor, describe the experimental evidence showing that angptl2 is a marker of senescence in vitro and in vivo, and discuss the impact of angptl2-related senescence in both physiological and pathological conditions. Future work is needed to demonstrate whether the senescence marker angptl2 is a potential clinical biomarker of age-related diseases.

Emerging roles of angiopoietin-like proteins in inflammation: Mechanisms and potential as pharmacological targets

Angiopoietin-like proteins (ANGPTLs), a family of eight secreted glycoproteins termed ANGTPL1-8, are involved in angiogenesis, lipid metabolism, cancer progression, and inflammation. Their roles in regulating lipid metabolism have been intensively studied, as some ANGPTLs are promising pharmacological targets for hypertriglyceridemia and associated cardiovascular disease. Recently, the emerging roles of ANGPTLs in inflammation have attracted great attention. First, elevated levels of multiple circulating ANGPTLs in inflammatory diseases make them potential disease biomarkers. Second, multiple ANGPTLs regulate acute or chronic inflammation via various mechanisms, including triggering inflammatory signaling through their action as ligands for integrin or forming homo- /hetero-oligomers to regulate signal transduction via extra- or intracellular mechanisms. As dysregulation of the inflammatory response is a critical trigger in many diseases, understanding the roles of ANGPTLs in inflammation will aid in drug/therapy development. Here, we summarize the roles, mechanisms, and potential therapeutic values for ANGPTLs in inflammation and inflammatory diseases.

Hepatokines and adipokines in NASH-related hepatocellular carcinoma

The incidence of hepatocellular carcinoma (HCC) is increasing in industrialised societies; this is likely secondary to the increasing burden of non-alcoholic fatty liver disease (NAFLD), its progressive form non-alcoholic steatohepatitis (NASH), and the metabolic syndrome. Cumulative studies suggest that NAFLD-related HCC may also develop in non-cirrhotic livers. However, prognosis and survival do not differ between NAFLD- or virus-associated HCC. Thus, research has increasingly focused on NAFLD-related risk factors to better understand the biology of hepatocarcinogenesis and to develop new diagnostic, preventive, and therapeutic strategies. One important aspect thereof is the role of hepatokines and adipokines in NAFLD/NASH-related HCC. In this review, we compile current data supporting the use of hepatokines and adipokines as potential markers of disease progression in NAFLD or as early markers of NAFLD-related HCC. While much work must be done to elucidate the mechanisms and interactions underlying alterations to hepatokines and adipokines, current data support the possible utility of these factors - in particular, angiopoietin-like proteins, fibroblast growth factors, and apelin - for detection or even as therapeutic targets in NAFLD-related HCC.

New Blood Biomarkers for the Diagnosis of AFP-Negative Hepatocellular Carcinoma

An early diagnosis of hepatocellular carcinoma (HCC) followed by effective treatment is currently critical for improving the prognosis and reducing the associated economic burden. Alpha-fetoprotein (AFP) is the most widely used biomarker for HCC diagnosis. Based on elevated serum AFP levels as well as typical imaging features, AFP-positive HCC (APHC) can be easily diagnosed, but AFP-negative HCC (ANHC) is not easily detected due to lack of ideal biomarkers and thus mainly reliance on imaging. Imaging for the diagnosis of ANHC is probably insufficient in sensitivity and/or specificity because most ANHC tumors are small and early-stage HCC, and it is involved in sophisticated techniques and high costs. Moreover, ANHC accounts for nearly half of HCC and exhibits a better prognosis compared with APHC. Therefore, the diagnosis of ANHC in clinical practice has been a critical issue for the early treatment and prognosis improvement of HCC. In recent years, tremendous efforts have been made to discover new biomarkers complementary to AFP for HCC diagnosis. In this review, we systematically review and discuss the recent advances of blood biomarkers for HCC diagnosis, including DNA biomarkers, RNA biomarkers, protein biomarkers, and conventional laboratory metrics, focusing on their diagnostic evaluation alone and in combination, in particular on their diagnostic performance for ANHC.

Mining the role of angiopoietin-like protein family in gastric cancer and seeking potential therapeutic targets by integrative bioinformatics analysis

BACKGROUND

The indistinctive effects of antiangiogenesis agents in gastric cancer (GC) can be attributed to multifaceted gene dysregulation associated with angiogenesis. Angiopoietin-like (ANGPTL) proteins are secreted proteins regulating angiogenesis. They are also involved in inflammation and metabolism. Emerging evidences have revealed their various roles in carcinogenesis and metastasis development. However, the mRNA expression profiles, prognostic values, and biological functions of ANGPTL proteins in GC are still elucidated.

METHODS

We compared the transcriptional expression levels of ANGPTL proteins between GC and normal gastric tissues using ONCOMINE and TCGA-STAD. The prognostic values were evaluated by LinkedOmics and Kaplan-Meier Plotter, while the association of expression levels with clinicopathological features was generated through cBioPortal. We conducted the functional enrichment analysis with Metascape.

RESULTS

The expression of ANGPTL1/3/6 was lower in GC tissues than in normal gastric tissues. High expression of ANGPTL1/2/4 was correlated with short overall survival and post-progression survival in GC patients. Upregulated ANGPTL1/2 was correlated with higher histological grade, non-intestinal Lauren classification, and advanced T stage, while ANGPTL4 exhibited high expression in early T stage, M1 stage, and non-intestinal Lauren classification.

CONCLUSIONS

Integrative bioinformatics analysis suggests that ANGPTL1/2/4 may be potential therapeutic targets in GC patients. Among them, ANGPTL2 acts as a GC promoter, while ANGPTL1/4's role in GC is still uncertain.

Expression of ANGPTL2 and its impact on papillary thyroid cancer

Background

Although the most thyroid carcinoma patients have good prognosis, around 20% of papillary thyroid carcinoma (PTC) patients have a high rate of metastasis and recurrence after routine treatment, which causes high lethality with these patients. Tumor proliferation, metastasis, and invasion are important predictors of PTC invasiveness and are key factors in cancer-related death. Angiopoietin-like 2 (ANGPTL2), a secreted protein which belongs to the angiopoietin (ANGPTL) family, was reported to be involved in the regulation of several different type of cancer cell proliferation and metastasis. However, whether ANGPTL2 plays a role in the progression of PTC, particularly in metastasis and recurrence of PTC, remains unclear. Hence, the purpose of this study was to evaluate the level of ANGPTL2 in PTC and normal thyroid, as well as para-cancerous tissue. Furthermore, the impact of ANGPTL2 on PTC cell proliferation, metastasis, recurrence and invasion was assessed to investigate the possibility whether ANGPTL2 may become a novel target for PTC therapy and cancer prognosis.

Materials and methods

The level of ANGPTL2 in PTC and para-cancerous tissue was assessed by immunohistochemistry. The biological effect of ANGPTL2 on thyroid cancer cell proliferation and metastasis was investigated by the Cell Counting Kit-8 (CCK8) assay, cell scratch test, and transwell assay. Correlations of ANGPTL2 expression levels with proliferation, migration, and metastasis of thyroid cancer were assessed with the TCGA data set and analyzed by gene set enrichment analysis. Receiver operating characteristic analysis was used to evaluate the utility of ANGPTL2 as a biomarker for prediction of thyroid cancer. Survival analysis was performed using the thyroid cancer database in K-M Plotter to detect correlations between survival time and ANGPTL2 levels.

Results

Current study revealed that: (1) ANGPTL2 was highly expressed in thyroid cancer in comparison with adjacent normal thyroid tissue; (2) ANGPTL2 expression was increased with thyroid tumor progression; (3) ANGPTL2 increased proliferation of thyroid cancer cells; (4) ANGPTL2 promoted migration and invasion of thyroid cancer cells; (5) high level of ANGPTL2 in thyroid cancer patients were significantly associated with a poor prognosis. The patients showed a higher metastasis and recurrence rate.

Conclusion

ANGPTL2 promoted and enhanced proliferation, metastasis, and invasion of thyroid cancer cells. ANGPTL2 may be considered as a potential biomarker for diagnosis and prognosis of thyroid cancer patients. Further evaluation needs to be done to analyze the possibility of taking ANGPTL2 as a prognostic marker and therapeutic target for papillary thyroid cancer.

Diagnostic value of angiopoietin-like protein 2 for CHB-related hepatocellular carcinoma

Purpose

Angiopoietin-like protein 2 (ANGPTL2) is a secretory glycoprotein with various functions in vascular biology, inflammation and tumor development. As shown in our previous studies, ANGPTL2 expression positively correlates with liver fibrosis stages in chronic hepatitis B (CHB) patients. The aim of this study was further to assess whether ANGPTL2 represents a potential biomarker for detecting hepatocellular carcinoma (HCC).

Patients and methods

This study enrolled 361 participants including healthy controls (HCs) and patients with CHB, liver cirrhosis (LC) and HCC. A discovery cohort consisted of 35 HCs and 55 patients with HCC. A total of 271 participants, including 45 HCs, 125 patients with CHB, 38 patients with LC, and 63 patients with HCC were enrolled in a validation cohort. Serum ANGPTL2 levels were detected using a human ANGPTL2 assay kit, and hepatic expression of ANGPTL2 was analyzed using immunohistochemistry.

Results

In the discovery cohort, a significantly higher serum ANGPTL2 level was detected in HCC than in HCs (73.49±33.87 vs 30.54±9.86; p<0.001). The results of the receiver operating characteristic curve indicated a significantly higher area under the curve for the ability of the ANGPTL2 to predict HCC than alpha fetoprotein (AFP). In the validation cohort, serum ANGPTL2 level gradually increased with the progression of chronic hepatitis B virus infection and reached the highest level in HCC. Immunohistochemical staining also confirmed these findings. The serum ANGPTL2 displayed better diagnostic efficiency not only for differentiating HCC from HC but also for differentiating HCC from high-risk controls (CHB+LC). Furthermore, the combination of ANGPTL2 and AFP may increase the diagnostic accuracy for HCC compared to ANGPTL2 or AFP alone. Importantly, ANGPTL2 levels also correlated with the detection of AFP-negative HCC.

Conclusions

ANGPTL2 may be used as a promising biomarker for the diagnosis of CHB-related HCC.

The Roles of ANGPTL Families in Cancer Progression

Angiopoietins play important roles in angiogenesis and the maintenance of hematopoietic stem cells. Angiopoietin-like proteins (ANGPTLs) are identified as proteins structurally similar to angiopoietins, and the ANGPTL family now consists of eight members. ANGPTLs are secretary proteins, and some ANGPTLs are not only angiogenic factors but also proteins with multiple functions such as glucose metabolism, lipid metabolism, redox regulation and chronic inflammation. Chronic inflammation is one of the key factors in carcinogenesis and cancer growth, proliferation, invasion and metastasis. ANGPTL 2, 3, 4, 6 and 7 are pro-inflammatory factors and regulate cancer progression, while ANGPTL1 inhibits tumor angiogenesis and metastasis. In this review, we describe the roles of ANGPTLs in cancer progression and discuss the possibility of disturbing the progression of cancer by regulating ANGPTLs expression.

Angiopoietin-Like Proteins in Angiogenesis, Inflammation and Cancer

Altered expression of secreted factors by tumor cells or cells of the tumor microenvironment is a key event in cancer development and progression. In the last decade, emerging evidences supported the autocrine and paracrine activity of the members of the Angiopoietin-like (ANGPTL) protein family in angiogenesis, inflammation and in the regulation of different steps of carcinogenesis and metastasis development. Thus, ANGPTL proteins become attractive either as prognostic or predictive biomarkers, or as novel target for cancer treatment. Here, we outline the current knowledge about the functions of the ANGPTL proteins in angiogenesis, cancer progression and metastasis. Moreover, we discuss the most recent evidences sustaining their role as prognostic or predictive biomarkers for cancer therapy. Although the role of ANGPTL proteins in cancer has not been fully elucidated, increasing evidence suggest their key effects in the proliferative and invasive properties of cancer cells. Moreover, given the common overexpression of ANGPTL proteins in several aggressive solid tumors, and their role in tumor cells and cells of the tumor microenvironment, the field of research about ANGPTL proteins network may highlight new potential targets for the development of future therapeutic strategies.

Angiopoietin-like protein as a novel marker for liver fibrosis in chronic hepatitis B patients with normal to minimally raised ALT

Background

For hepatitis B patients who do not meet the treatment criteria recommended by guidelines, therapy decisions depend on hepatic histology. Angiopoietin-like protein 2 (Angptl2) is a mediator of chronic inflammation that contributes to extracellular matrix remodeling. The aim of this study was to explore the predictive value of Angptl2 as a novel biomarker of liver histology.

Methods

Hepatitis B patients with normal to minimally raised ALT were recruited. Serum Angptl2 concentrations were detected using commercial ELISA kit. The fibrosis score were assessed according to Ishak criteria. Significant fibrosis was defined as ISHAK score ≥ 3.

Results

Of 460 patients, 223 cases served as training cohort and 237 ones as validation cohort. Serum Angptl2 concentration was significantly associated with fibrosis scores in both training and validation group. Angptl2 combined index (ACI) for assessing significant fibrosis was developed from training cohort, based on Angptl2 and conventional variables. ACI showed areas under receiver-operating characteristic curve (AUC) of 0.835 for predicting significant fibrosis, which was superior to APRI (AUC = 0.776, P = 0.049), FIB-4 (AUC = 0.750, P = 0.010), Hui model (AUC = 0.756, P = 0.028), and had a better trend than Forn’s index (AUC = 0.796, P = 0.083) in training cohort. Finally, validation cohort revealed its robustness and reliability.

Conclusion

Higher Angptl2 level represents as a potential biomarker independently associated with fibrosis stages. Compared with APRI, Hui model, FIB-4, Forn’s index, ACI did better in diagnosing significant fibrosis in hepatitis B patients.

Trial registration

The complete clinical trials protocol is available by request at clinicaltrials.gov (NCT01962155) and chictr.org (ChiCTR-DDT-13003724).

Electronic supplementary material

The online version of this article (10.1186/s12879-017-2728-7) contains supplementary material, which is available to authorized users.

High Circulating Levels of ANGPTL2: Beyond a Clinical Marker of Systemic Inflammation

Angiopoietin-like 2 (ANGPTL2) is a proinflammatory protein belonging to the angiopoietin-like family. ANGPTL2 is secreted and detected in the systemic circulation. Different observational clinical studies reported that circulating levels of ANGPTL2 increase significantly in various chronic inflammatory diseases and showed associations between ANGPTL2 levels and diagnosis and/or prognosis of cardiovascular diseases, diabetes, chronic kidney disease, and various types of cancers. However, these studies did not address the following questions: (a) what are the sources of circulating ANGPTL2? (b) How and by which mechanisms an increase in circulating ANGPTL2 contributes to the pathogenesis of chronic inflammatory diseases? (c) Does an increase in circulating levels of ANGPTL2 measured in a well-defined chronic medical condition originate from a specific cell type? Mechanistic hypotheses have been proposed based on studies performed in mice and cultured cells, and proinflammatory, prooxidative, proangiogenic, proliferative, and antiapoptotic properties of ANGPTL2 have been reported. The aim of this review is to propose answers concerning the potential sources of circulating ANGPTL2 and its common pathological properties associated with various chronic inflammatory diseases and death in humans. We believe that high circulating ANGPTL2 levels are more than an inflammatory marker and may reflect the senescent cellular load of an individual.

LILRB receptor-mediated regulation of myeloid cell maturation and function

The leukocyte immunoglobulin-like receptor (LILR) family comprises a set of paired immunomodulatory receptors expressed among human myeloid and lymphocyte cell populations. While six members of LILR subfamily A (LILRA) associate with membrane adaptors to signal via immunoreceptor tyrosine-based activating motifs (ITAM), LILR subfamily B (LILRB) members signal via multiple cytoplasmic immunoreceptor tyrosine-based inhibitory motifs (ITIM). Ligand specificity of some LILR family members has been studied in detail, but new perspective into the immunoregulatory aspects of this receptor family in human myeloid cells has been limited. LILRB receptors and the murine ortholog, paired immunoglobulin-like receptor B (PIRB), have been shown to negatively regulate maturation pathways in myeloid cells including mast cells, neutrophils, dendritic cells, as well as B cells. Our laboratory further demonstrated in mouse models that PIRB regulated functional development of myeloid-derived suppressor cell and the formation of a tumor-permissive microenvironment. Based on observations from the literature and our own studies, our laboratory is focusing on how LILRs modulate immune homeostasis of human myeloid cells and how these pathways may be targeted in disease states. Integrity of this pathway in tumor microenvironments, for example, permits a myeloid phenotype that suppresses antitumor adaptive immunity. This review presents the evidence supporting a role of LILRs as myeloid cell regulators and ongoing efforts to understand the functional immunology surrounding this family.

ANGPTL2 expression in gastric cancer tissues and cells and its biological behavior

AIM

To explore expression of angiopoietin-like protein 2 (ANGPTL2) and its effect on biological behavior such as proliferation and invasiveness in gastric cancer.

METHODS

Western blotting was used to detect expression of ANGPTL2 in 60 human normal gastric tissues, 60 human gastric cancer tissues and gastric cell lines including GES-1, N87, SGC7901, BGC823 and PAMC82. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Transwell assay were used to detect the proliferation and invasive ability of gastric cancer cells.

RESULTS

Compared to normal tissues, ANGPTL2 protein levels were significantly upregulated in gastric tissues, and this level was closely correlated with gastric tumor grade, clinical stage and lymph node metastasis. Compared to GES-1 cells, ANGPTL2 mRNA and protein levels were significantly increased in gastric cancer cells including N87, SGC7901, BGC823 and PAMC82. The expression of ANGPTL2 in highly malignant gastric cancer cell lines BGC823 and PAMC82 was significantly higher than in low malignancy gastric cancer cell lines N87 and SGC7901. MTT and Transwell experiments indicated that the proliferation rate and invasive ability of stable overexpressed gastric cancer cells was faster than in cells transfected with Lv-NC and blank control cells, and the invasive ability of stable overexpressed gastric cancer cells was higher than that of cells transfected with Lv-NC and blank control cells.

CONCLUSION

ANGPTL2 contributed to proliferation and invasion of gastric cancer cells. In clinical treatment, ANGPTL2 may become a new target for treatment of gastric cancer.

A role for novel adipose tissue-secreted factors in obesity-related carcinogenesis

Obesity, a pandemic disease, is caused by an excessive accumulation of fat that can have detrimental effects on health. Adipose tissue plays a very important endocrine role, secreting different molecules that affect body physiology. In obesity, this function is altered, leading to a dysfunctional production of several factors, known as adipocytokines. This process has been linked to various comorbidities associated with obesity, such as carcinogenesis. In fact, several classical adipocytokines with increased levels in obesity have been demonstrated to exert a pro-carcinogenic role, including leptin, TNF-α, IL-6 and resistin, whereas others like adiponectin, with decreased levels in obesity, might have an anti-carcinogenic function. In this expanding field, new proteomic techniques and approaches have allowed the identification of novel adipocytokines, a number of which exhibit an altered production in obesity and type 2 diabetes and thus are related to adiposity. Many of these novel adipocytokines have also been identified in various tumour types, such as that of the breast, liver or endometrium, thereby increasing the list of potential contributors to carcinogenesis. This review is focused on the regulation of these novel adipocytokines by obesity, including apelin, endotrophin, FABP4, lipocalin 2, omentin-1, visfatin, chemerin, ANGPTL2 or osteopontin, emphasizing its involvement in tumorigenesis.

Serum angiopoietin-like protein 2 as a potential biomarker for diagnosis, early recurrence and prognosis in gastric cancer patients

Chronic inflammation of gastric mucosa by Helicobacter pylori infection can initiate gastric carcinogenesis. As angiopoietin-like protein 2 (ANGPTL2) mediates inflammation and inflammation-associated carcinogenesis, we investigated the functional and clinical significance of ANGPTL2 in human gastric cancer (GC). SiRNA knockdown studies were performed for the functional assessment of ANGPTL2 in GC cell lines. ANGPTL2 expression was evaluated immunohistochemically in 192 tissue specimens from GC patients. In addition, we screened serum ANGPTL2 levels from 32 GC patients and 23 healthy controls; and validated these results in 194 serum samples from GC patients and 45 healthy controls by ELISA. ANGPTL2 knockdown caused anoikis and inhibited proliferation, invasion and migration in GC cells. ANGPTL2 expression was upregulated in GC tissues compared to normal gastric mucosa; and high ANGPTL2 expression was significantly associated with tumor progression, early recurrence (P = 0.003) and poor prognosis (P = 0.007). Serum ANGPTL2 in GC patients was significantly higher than for healthy controls (P < 0.05), and accurately distinguished GC patients from healthy control (AUC = 0.865). The validation step confirmed significantly higher serum ANGPTL2 levels in GC patients than healthy controls (P < 0.0001). Receiver operating characteristic curves yielded robust AUC value (0.831) accompanied by high sensitivity (73.0%) and specificity (82.2%) in distinguishing GC patients from healthy controls. High serum ANGPTL2, rather than its expression in matched tissues, was significantly associated with tumor progression, and emerged as an independent marker for recurrence (HR: 5.05, P = 0.0004) and prognosis (HR: 3.6, P = 0.01). Serum ANGPTL2 expression is a potential noninvasive biomarker for diagnosis, early recurrence and prognosis of GC patients.