Angiopoietin-like protein 2 renders colorectal cancer cells resistant to chemotherapy by activating spleen tyrosine kinase-phosphoinositide 3-kinase-dependent anti-apoptotic signaling

Mechanisms by which obesity regulates inflammation and anti-tumor immunity in cancer

Obesity is associated with an increased risk for 13 different cancers. The increased risk for cancer in obesity is mediated by obesity-associated changes in the immune system. Obesity has distinct effects on different types of inflammation that are tied to tumorigenesis. For example, obesity promotes chronic inflammation in adipose tissue that is tumor-promoting in peripheral tissues. Conversely, obesity inhibits acute inflammation that rejects tumors. Obesity therefore promotes cancer by differentially regulating chronic versus acute inflammation. Given that obesity is chronic, the initial inflammation in adipose tissue will lead to systemic inflammation that could induce compensatory anti-inflammatory reactions in peripheral tissues to suppress chronic inflammation. The overall effect of obesity in peripheral tissues is therefore dependent on the duration and severity of obesity. Adipose tissue is a complex tissue that is composed of many cell types in addition to adipocytes. Further, adipose tissue cellularity is different at different anatomical sites throughout the body. Consequently, the sensitivity of adipose tissue to obesity is dependent on the anatomical location of the adipose depot. For example, obesity induces more inflammation in visceral than subcutaneous adipose tissue. Based on these studies, the mechanisms by which obesity promotes tumorigenesis are multifactorial and immune cell type-specific. The objective of our paper is to discuss the cellular mechanisms by which obesity promotes tumorigenesis by regulating distinct types of inflammation in adipose tissue and the tumor microenvironment.

Angiopoietin-Like Protein 2 Expression in Tumor Cells Supports Tumor-Associated Macrophage-Induced Tumor Progression in Esophageal Cancer

BACKGROUND

Tumor-associated macrophages (TAM), a major component of the tumor microenvironment, play key roles in tumor formation and progression; however, mechanisms underlying TAM-induced tumor progression are complex and not well known. We previously reported that tumor cell-derived angiopoietin-like protein 2 (ANGPTL2) functions as a tumor promoter in some cancer contexts.

METHODS

We examined ANGPTL2 expression in paraffin-embedded tumor samples from resected specimens of 221 patients with esophageal cancer. Patients were subdivided into four groups based on immunohistochemistry scores described above: ANGPTL2-low/TAM-low, ANGPTL2-low/TAM-high, ANGPTL2-high/TAM-low, and ANGPTL2-high/TAM-high groups. Gene expression datasets of esophageal cancer cell lines were obtained from the cancer cell line encyclopedia public database.

RESULTS

In this study, we demonstrate that TAM infiltration is associated with poor prognosis in patients with esophageal cancer whose tumor cells show relatively higher ANGPTL2 expression levels; however, TAM infiltration did not affect prognosis in patients with ANGPTL2-low-expressing esophageal cancer, suggesting that ANGPTL2 expression in esophageal cancer cells is required for TAM-induced tumor progression. Our analysis of public datasets indicates a potential positive correlation of ANGPTL2 expression levels with that of transforming growth factor (TGF)-β, a TAM-activating factor, in esophageal cancer cell lines.

CONCLUSION

We conclude that ANGPTL2 signaling in tumor cells supports TAM-induced tumor progression and contributes to poor prognosis in patients with esophageal cancer. These findings overall provide novel insight into pro-tumor ANGPTL2 functions and illustrate the essential role of cancer cell/TAM crosstalk in cancer progression.

Comparative transcriptomic analysis validates iPSC derived in-vitro progressive fibrosis model as a screening tool for drug discovery and development in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by vasculopathy, immune dysregulation, and systemic fibrosis. Research on SSc has been hindered largely by lack of relevant models to study the progressive nature of the disease and to recapitulate the cell plasticity that is observed in this disease context. Generation of models for fibrotic disease using pluripotent stem cells is important for recapitulating the heterogeneity of the fibrotic tissue and are a potential platform for screening anti-fibrotic drugs. We previously reported a novel in-vitro model for fibrosis using induced pluripotent stem cell-derived mesenchymal cells (iSCAR). Here we report the generation of a "scar-like phenotype" when iPSC derived mesenchymal cells are cultured on hydrogel that mimicks a wound healing/scarring response (iSCAR). First, we performed RNA sequencing (RNA-seq) based transcriptome profiling of iSCAR culture at 48 h and 13 days to characterize early and latestage scarring phenotypes. The next generation RNA-seq of these iSCAR culture at different timepoints detected expression 92% of early "scar associated" genes and 85% late "scar associated" genes, respectively. Comparative transcriptomic analysis of a gene level SSc compendium matrix to the iSCAR wound associated model revealed genes common in both data sets. Early scar formation genes showed biological processes of hypoxia (27.5%), vascular development (13.7%) and glycolysis (27.5), while late scar formation showed genes associated with senescence (22.6%). Next we show the effects of two different antifibrotic compounds to validate the utility of the model as a screening tool to study early and late-stagelate-stage fibrosis. An autotaxin inhibitor was used to validate the iSCAR late stage fibrotic model (iSCAR-T) and an antifibrotic tool screening compound of unknown mechanism (EX00015097) was used to study and validate both early (iSCAR-P) and late-stage (iSCAR-T) fibrosis in the iSCAR model.

Host ANGPTL2 establishes an immunosuppressive tumor microenvironment and resistance to immune checkpoint therapy

Use of immune checkpoint inhibitors (ICIs) as cancer immunotherapy has advanced rapidly in the clinic; however, mechanisms underlying resistance to ICI therapy, including impaired T cell infiltration, low immunogenicity, and tumor "immunophenotypes" governed by the host, remain unclear. We previously reported that in some cancer contexts, tumor cell-derived angiopoietin-like protein 2 (ANGPTL2) has tumor-promoting functions. Here, we asked whether ANGPTL2 deficiency could enhance antitumor ICI activity in two inflammatory contexts: a murine syngeneic model of colorectal cancer and a mouse model of high-fat diet (HFD)-induced obesity. Systemic ANGPTL2 deficiency potentiated ICI efficacy in the syngeneic model, supporting an immunosuppressive role for host ANGPTL2. Relevant to the mechanism, we found that ANGPTL2 induces pro-inflammatory cytokine production in adipose tissues, driving generation of myeloid-derived suppressor cells (MDSCs) in bone marrow and contributing to an immunosuppressive tumor microenvironment and resistance to ICI therapy. Moreover, HFD-induced obese mice showed impaired responsiveness to ICI treatment, suggesting that obesity-induced chronic inflammation facilitated by high ANGPTL2 expression blocks ICI antitumor effects. Our findings overall provide novel insight into protumor ANGPTL2 functions and illustrate the essential role of the host system in ICI responsiveness.

Tumor stroma-derived ANGPTL2 potentiates immune checkpoint inhibitor efficacy

Use of immune checkpoint inhibitors (ICIs) as cancer immunotherapy has advanced rapidly in the clinic. We recently reported that tumor stroma-derived angiopoietin-like protein 2 (ANGPTL2) has tumor suppressive activity by enhancing dendritic cell-mediated CD8+ T cell anti-tumor immune responses. However, a direct impact of ANGPTL2 on ICI anti-tumor effect remains unclear. Here, we use a murine syngeneic model to show that host ANGPTL2 facilitates CD8+ T cell cross-priming and contributes to anti-tumor responses to ICIs in this context. Importantly, our analysis of public datasets indicated that ANGPTL2 expression is associated with positive responses to ICI therapy by human melanoma patients. We conclude that ANGPTL2-mediated stromal cell crosstalk facilitates anti-tumor immunity and ICI responsiveness. These findings overall provide novel insight into ANGPTL2 anti-tumor function and regulation of ICI-induced anti-tumor immunity.

ANGPTL2-mediated epigenetic repression of MHC-I in tumor cells accelerates tumor immune evasion

Loss or downregulation of major histocompatibility complex class I (MHC-I) contributes to tumor immune evasion. We previously demonstrated that angiopoietin-like protein 2 (ANGPTL2) promotes tumor progression using a Xp11.2 translocation renal cell carcinoma (tRCC) mouse model. However, molecular mechanisms underlying ANGPTL2 tumor-promoting activity in the tRCC model remained unclear. Here, we report that ANGPTL2 deficiency in renal tubular epithelial cells slows tumor progression in the tRCC mouse model and promotes activated CD8+ T-cell infiltration of kidney tissues. We also found that Angptl2-deficient tumor cells show enhanced interferon γ-induced expression of MHC-I and increased susceptibility to CD8+ T-cell-mediated anti-tumor immune responses. Moreover, we provide evidence that the ANGPTL2-α5β1 integrin pathway accelerates polycomb repressive complex 2-mediated repression of MHC-I expression in tumor cells. These findings suggest that ANGPTL2 signaling in tumor cells contributes to tumor immune evasion and that suppressing that signaling in tumor cells could serve as a potential strategy to facilitate tumor elimination by T-cell-mediated anti-tumor immunity.

1-Monopalmitin promotes lung cancer cells apoptosis through PI3K/Akt pathway in vitro

Lung cancer is the leading cause of cancer-related death worldwide and non-small cell lung cancer (NSCLC) represents 85%. Mougeotia nummuloides and Spirulina major have been reported to possess anticancer properties. 1-Monopalmitin (1-Mono) is the principle active constituent in these natural plants. It is debating whether 1-Mono exerts antitumor effects. Therefore, we explored the role of 1-Mono in lung cancer in vitro. Results showed that 1-Mono significantly inhibited A549 and SPC-A1 cell proliferation, induced G2/M arrest and caspase-dependent apoptosis. Moreover, it suppressed the protein expression of inhibitors of apoptosis proteins (IAPs). It was further demonstrated that 1-Mono activated the PI3K/Akt pathway, suppression of PI3K/Akt activities with LY294002 and Wortmannin partially attenuated 1-Mono-mediated anticancer activities, indicating that 1-Mono-induced antitumor effects is dependent on PI3K/Akt pathway. 1-Mono induced cytoprotective autophagy since autophagy inhibitor Chloroquine dramatically enhanced 1-Mono-induced cytotoxicity. In summary, our results showed 1-Mono kills lung cancer through PI3K/Akt pathway, providing novel options for lung cancer administration.

Tumor cell-derived ANGPTL2 promotes β-catenin-driven intestinal tumorigenesis

Uncontrolled proliferation of intestinal epithelial cells caused by mutations in genes of the WNT/β-catenin pathway is associated with development of intestinal cancers. We previously reported that intestinal stromal cell-derived angiopoietin-like protein 2 (ANGPTL2) controls epithelial regeneration and intestinal immune responses. However, the role of tumor cell-derived ANGPTL2 in intestinal tumorigenesis remained unclear. Here, we show that tumor cell-derived ANGPTL2 promotes β-catenin-driven intestinal tumorigenesis. ANGPTL2 deficiency suppressed intestinal tumor development in an experimental mouse model of sporadic colon cancer. We also found that increased ANGPTL2 expression in colorectal cancer (CRC) cells augments β-catenin pathway signaling and promotes tumor cell proliferation. Relevant to mechanism, our findings suggest that tumor cell-derived ANGPTL2 upregulates expression of OB-cadherin, which then interacts with β-catenin, blocking destruction complex-independent proteasomal degradation of β-catenin proteins. Moreover, our observations support a model whereby ANGPTL2-induced OB-cadherin expression in CRC cells is accompanied by decreased cell surface integrin α5β1 expression. These findings overall provide novel insight into mechanisms of β-catenin-driven intestinal tumorigenesis.

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.

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.

Angiopoietin-like Proteins in Colorectal Cancer-A Literature Review

Colorectal cancer (CRC) is one of the most common types of malignancy, with an annual incidence of about 10% of the total number of new cases. Despite well-developed screening tests, mortality from this type of cancer remains unchanged. Therefore, it is important to search for more accurate markers that are useful in the detection of colorectal cancer (especially in its early stages), and treatment. Angiopoietin-like proteins (ANGPTLs) are a family of eight proteins with a diversity of applications, including pro- and anti-angiogenic properties. Consequently, we performed an extensive search of the literature, pertaining to our investigation, via the MEDLINE/PubMed database. Based on the available literature, we summarize that some of those proteins are characterized by increased or decreased concentrations during the course of CRC. We can also assume that some ANGPTLs can inhibit the development of CRC, while others induce its progress. Moreover, some factors are dependent on the stage or histological type of the tumor, the presence of hypoxia, or metastases. Most importantly, some ANGPTLs can be useful in anti-cancer therapy. Therefore, further studies on ANGPTLs as potential markers of CRC should be continued.

Stroma-derived ANGPTL2 establishes an anti-tumor microenvironment during intestinal tumorigenesis

Previous studies show that tumor cell-derived angiopoietin-like protein 2 (ANGPTL2) functions as a tumor promoter in some cancer contexts. However, we recently reported that host ANGPTL2 also shows tumor suppressive activity by enhancing dendritic cell-mediated CD8⁺ T cell anti-tumor immune responses in mouse kidney cancer and murine syngeneic models. However, mechanisms underlying ANGPTL2-mediated tumor suppression are complex and not well known. Here, we investigated ANGPTL2 tumor suppressive function in chemically-induced intestinal tumorigenesis. ANGPTL2 deficiency enhanced intestinal tumor growth in an experimental mouse colitis-associated colon cancer (CAC) model. Angptl2-deficient mice also showed a decrease not only in CD8⁺ T cell responses but in CD4⁺ T cell responses during intestinal tumorigenesis. Furthermore, we show that stroma-derived ANGPTL2 can activate the myeloid immune response. Notably, ANGPTL2 drove generation of immunostimulatory macrophages via the NF-κB pathway, accelerating CD4⁺ T helper 1 (Th1) cell activation. These findings overall provide novel insight into the complex mechanisms underlying ANGPTL2 anti-tumor function in cancer pathology.

Knockdown of angiopoietin-like 2 induces clearance of vascular endothelial senescent cells by apoptosis, promotes endothelial repair and slows atherogenesis in mice

Elimination of senescent cells (SnC) is anti-atherogenic, but the specific contribution of senescent vascular endothelial cells (EC) is unknown. We inactivated angiopoietin like-2 (angptl2), a marker of SnEC and a pro-atherogenic cytokine in LDLr^-/-, hApoB₁₀₀^+/+ atherosclerotic (ATX) mice. Three months after a single vascular delivery of a small hairpin (sh)Angptl2 in 3-month old ATX mice using an adeno-associated virus serotype 1 (AAV1), aortic atheroma plaque progression was slowed by 58% (p<0.0001). In the native aortic endothelium, angptl2 expression was decreased by 80%, in association with a reduced expression of p21, a cyclin-dependent kinase inhibitor overexpressed in growth-arrested SnC. Endothelial activation was reduced (lower Icam-1, Il-1β and Mcp-1 expression), decreasing monocyte Cd68 expression in the endothelium. One week post-injection, the ratio Bax/Bcl2 increased in the endothelium only, suggesting that angptl2⁺/p21⁺ SnEC were eliminated by apoptosis. Four weeks post-injection, the endothelial progenitor marker Cd34 increased, suggesting endothelial repair. In arteries of atherosclerotic patients, we observed a strong correlation between p21 and ANGPTL2 (r=0.727, p=0.0002) confirming the clinical significance of angptl2-associated senescence. Our data suggest that therapeutic down-regulation of vascular angptl2 leads to the clearance of SnEC by apoptosis, stimulates endothelial repair and reduces atherosclerosis.

Dual functions of angiopoietin-like protein 2 signaling in tumor progression and anti-tumor immunity

Angiopoietin-like protein 2 (ANGPTL2) is a secreted glycoprotein homologous to angiopoietins. Previous studies suggest that tumor cell-derived ANGPTL2 has tumor-promoting function. Here, we conducted mechanistic analysis comparing ANGPTL2 function in cancer progression in a murine syngeneic model of melanoma and a mouse model of translocation renal cell carcinoma (tRCC). ANGPTL2 deficiency in tumor cells slowed tRCC progression, supporting a tumor-promoting role. However, systemic ablation of ANGPTL2 accelerated tRCC progression, supporting a tumor-suppressing role. The syngeneic model also demonstrated a tumor-suppressing role of ANGPTL2 in host tumor microenvironmental cells. Furthermore, the syngeneic model showed that PDGFRα⁺ fibroblasts in the tumor microenvironment express abundant ANGPTL2 and contribute to tumor suppression. Moreover, host ANGPTL2 facilitates CD8⁺ T-cell cross-priming and enhances anti-tumor immune responses. Importantly, ANGPTL2 activates dendritic cells through PIR-B-NOTCH signaling and enhances tumor vaccine efficacy. Our study provides strong evidence that ANGPTL2 can function in either tumor promotion or suppression, depending on what cell type it is expressed in.

ANGPTL6-mediated angiogenesis promotes alpha fetoprotein-producing gastric cancer progression

Alpha-fetoprotein (AFP)-producing gastric cancer (AFPGC) is regarded as a rare but highly malignant gastric adenocarcinoma subtype and its clinic pathological presentation mimics hepatocellular carcinoma. However, the underlying mechanism of this disease remains elusive. The level of ANGPTL6 in AFPGC cell lines is much higher than that of common types of gastric cancer cells. A high level of ANGPTL6 confers a poor prognosis and is correlated with the expression of CD34 (an endothelial cell marker). ANGPTL6 promotes endothelial cell migration and tube formation, Moreover, ANGPTL6 knockdown inhibits cancer cell apoptosis and invasiveness. Mechanistically, ANGPTL6 activates the ERK1/2 and AKT pathways. Treatment of ERK1/2 or AKT inhibitor can attenuated cell migration and tube formation. ANGPTL6 loss results in tumor growth in vivo. Our study revealed that ANGPTL6 is an important driver gene of angiogenesis in AFPGC development. These findings provide not only an effective biomarker for diagnosis but also an attractive therapeutic target for use in AFPGC patients.

Roles of angiopoietin-like proteins in regulation of stem cell activity

Various types of stem cells reside in the body and self-renew throughout an organism's lifetime. Such self-renewal is essential for maintenance of tissue homeostasis and is co-ordinately regulated by stem cell-intrinsic signals and signals from stem cell niche. Angiopoietin is a niche-derived signalling molecule well known to contribute to maintenance of haematopoietic stem cells (HSCs). Angiopoietin-like proteins (ANGPTLs) are structurally similar to angiopoietin, and recent studies reveal that they function in angiogenesis, lipid and energy metabolism and regulation of inflammation. However, unlike angiopoietins, activities of ANGPTLs in stem cell maintenance have remained unclear. Recently, several studies have reported an association of ANGPTL signalling with stem cell maintenance. Here, we summarize those findings with a focus on HSCs, intestinal stem cells, neural stem cells and cancer stem cells and discuss mechanisms underlying ANGPTL-mediated stem cell maintenance.

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.

Cordycepin sensitizes breast cancer cells toward irradiation through elevating ROS production involving Nrf2

Radiation therapy toward malignancies is often ineffective owing to radioresistance of cancer cells. On the basis of anti-tumor properties of cordycepin, we examined the effects of cordycepin on sensitizing breast cancer cells toward radiotherapy. Cordycepin administration promoted G2/M arrest and apoptosis of MCF-7 and MDA-MB-231 cells resulting in restraining the proliferation of the cells in vitro and in vivo following irradiation. Mechanistic investigations showed that the breast cancer cells cultured with cordycepin harbored higher levels of intracellular reactive oxygen species (ROS) and incremental numbers of γ-H2AX foci after irradiation exposure. Importantly, cordycepin treatment down-regulated the expression levels of Nuclear factor erythroid 2-related factor (Nrf2) and a series of downstream genes, such as heme oxygenase-1 (HO-1), to enhance ROS in breast cancer cells exposed to irradiation. Together, our observations demonstrate that cordycepin treatment sensitizes breast carcinoma cells toward irradiation via Nrf2/HO-1/ROS axis. Thus, our findings provide novel insights into the function and the underlying mechanism of cordycepin in radiotherapy, and suggest that cordycepin might be employed as a radiosensitizer during radiotherapy toward breast cancer in a pre-clinical setting.

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.

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.

ANGPTL2 expression in the intestinal stem cell niche controls epithelial regeneration and homeostasis

The intestinal epithelium continually self-renews and can rapidly regenerate after damage. Dysregulation of intestinal epithelial homeostasis leads to severe inflammatory bowel disease. Additionally, aberrant signaling by the secreted protein angiopoietin-like protein 2 (ANGPTL2) causes chronic inflammation in a variety of diseases. However, little is known about the physiologic role of ANGPTL2 in normal tissue homeostasis and during wound repair following injury. Here, we assessed ANGPTL2 function in intestinal physiology and disease in vivo Although intestinal development proceeded normally in Angptl2-deficient mice, expression levels of the intestinal stem cell (ISC) marker gene Lgr5 decreased, which was associated with decreased transcriptional activity of β-catenin in Angptl2-deficient mice. Epithelial regeneration after injury was significantly impaired in Angptl2-deficient relative to wild-type mice. ANGPTL2 was expressed and functioned within the mesenchymal compartment cells known as intestinal subepithelial myofibroblasts (ISEMFs). ANGPTL2 derived from ISEMFs maintained the intestinal stem cell niche by modulating levels of competing signaling between bone morphogenetic protein (BMP) and β-catenin. These results support the importance of ANGPTL2 in the stem cell niche in regulating stemness and epithelial wound healing in the intestine.

Balancing signals in the intestinal niche

During intestinal regeneration, opposing gradients of Wnt and BMP signaling ensure successful differentiation along the crypt/villus axis. In this issue of The EMBO Journal, Horiguchi et al (2017) show how intestinal subepithelial myofibroblasts can influence cell fate decisions in the regenerating intestine via autocrine secretion of angiopoietin‐like protein 2 (ANGPTL2).

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.

Suppression of Spleen Tyrosine Kinase (Syk) by Histone Deacetylation Promotes, Whereas BAY61-3606, a Synthetic Syk Inhibitor Abrogates Colonocyte Apoptosis by ERK Activation

Spleen tyrosine kinase (Syk), a non-receptor tyrosine kinase, regulates tumor progression, either negatively or positively, depending on the tissue lineage. Information about the role of Syk in colorectal cancers (CRC) is limited, and conflicting reports have been published. We studied Syk expression and its role in differentiation and apoptosis of the colonocytes. Here, we reported for the first time that expression of two transcript variants of Syk is suppressed in colonocytes during butyrate-induced differentiation, which mediates apoptosis of HT-29 cells. Despite being a known HDAC inhibitor, butyrate deacetylates histone3/4 around the transcription start site (TSS) of Syk. Histone deacetylation precludes the binding of RNA Polymerase II to the promoter and inhibits transcription. Since butyrate is a colonic metabolite derived from undigested fibers, our study offers a plausible explanation of the underlying mechanisms of the protective role of butyrate as well as the dietary fibers against CRC through the regulation of Syk. We also report that combined use of butyrate and highly specific Syk inhibitor BAY61-3606 does not enhance differentiation and apoptosis of colonocytes. Instead, BAY completely abolishes butyrate-induced differentiation and apoptosis in a Syk- and ERK1/2-dependent manner. While butyrate dephosphorylates ERK1/2 in HT-29 cells, BAY re-phosphorylates it, leading to its activation. This study describes a novel mechanism of butyrate action in CRC and explores the role of Syk in butyrate-induced differentiation and apoptosis. In addition, our study highlights those commercial small molecule inhibitors, although attractive drug candidates should be used with concern because of their frequent off-target effects. J. Cell. Biochem. 118: 191-203, 2017. © 2016 Wiley Periodicals, Inc.

A phase I trial of mFOLFOX6 combined with the oral PI3K inhibitor BKM120 in patients with advanced refractory solid tumors

PURPOSE

The oral PI3K inhibitor BKM120 has been reported as safe and well tolerated in early phase clinical trials of advanced cancer patients. We performed a phase I trial of BKM120 plus mFOLFOX6 (5-FU/LV + oxaliplatin), a common chemotherapeutic backbone in GI malignancies, to establish the maximum tolerated dose (MTD) and characterize the safety and tolerability of the combination.

METHODS

Patients with advanced solid tumors received oral BKM120 daily combined with standard doses of mFOLFOX6 every 2 weeks of a 28 day cycle. The study utilized a standard 3 + 3 dose escalation schema.

RESULTS

A total of 17 patients received treatment with BKM120, 13 of which were evaluate for dose limited toxicity (DLT). The most common tumor types were colorectal cancer, cholangiocarcinoma, pancreatic cancer and hepatocellular carcinoma. DLT included grade 3 hyperglycemia, grade 3 AST/ALT elevation, grade 4 neutropenia and grade 4 thrombocytopenia. A total of 76 % of patients experienced treatment related grade 3/4 adverse events (AEs), the most common of which were neutropenia, fatigue, leukopenia, hyperglycemia and thrombocytopenia. One patient demonstrated an unconfirmed partial response and three patients had stable disease.

DISCUSSION

The MTD of BKM120 in combination with standard doses of mFOLFOX6 was 40 mg daily, which is well below the 100 mg daily dose proven effective and tolerable both as a single agent and in combination with other chemotherapeutics. In addition, the regimen of BKM120 with mFOLFOX6 in patients with refractory solid tumors resulted in increased toxicity than would be expected from either the PI3K inhibitor or the chemotherapy backbone alone.