[Abstract unavailable

Cancer is a leading cause of death worldwide. Tumor cells exploit various signaling pathways to promote their growth and metastasis. To our knowledge, the role of angiopoietin-like 4 protein (ANGPTL4) in cancer remains undefined. Here, we found that elevated ANGPTL4 expression is widespread in tumors, and its suppression impairs tumor growth associated with enhanced apoptosis. Tumor-derived ANGPTL4 interacts with integrins to stimulate NADPH oxidase-dependent production of O(2)(-). A high ratio of O(2)(-):H(2)O(2) oxidizes/activates Src, triggering the PI3K/PKBα and ERK prosurvival pathways to confer anoikis resistance, thus promoting tumor growth. ANGPTL4 deficiency results in diminished O(2)(-) production and a reduced O(2)(-):H(2)O(2) ratio, creating a cellular environment conducive to apoptosis. ANGPTL4 is an important redox player in cancer and a potential therapeutic target.

A retrospective cohort study including 112 patients suffering from esophageal squamous cell carcinoma (ESCC) was performed to investigate the expression of B7-H4 in ESCC and determine its association with patient's clinicopathological parameters and survival. Expression levels of B7-H4 on tumor cells and densities of tumor infiltrating lymphocytes (TILs) in the surgical specimens of ESCC tissues were characterized using immunohistochemical assays. Uni- and multivariate analyses were performed to evaluate the prognostic value of B7-H4 expression levels and densities of TILs in tumor sections. Positive B7-H4 immunostaining was observed in 107 of 112 (95.5%) of ESCC tissue sections. We further divided all patients into two major subgroups, a lower B7-H4 expression group with 46 patients and a higher B7-H4 expression group with 66 patients. We found that expression levels of B7-H4 on tumor cells were significantly correlated with patient's gender (P = 0.0288), distant metastasis (P = 0.0500), and TNM stage (P = 0.0258). Moreover, tumor cell B7-H4 expression was inversely correlated with densities of CD3(+) T cells in tumor nest (P = 0.0424) and CD8(+) T cells in tumor stroma (P = 0.0229). The overall survival rate of the patients with higher B7-H4 expression was significantly worse than that of the patients with lower B7-H4 expression (P = 0.0105, Hazard Ratio: 1.854, 95%CI:1.152-2.902). Markers of cell-mediated immune responses such as CD3, CD8, and T-bet were associated with better patient survival. The present study demonstrated that B7-H4 expression in human ESCC is associated with cancer progression, reduced tumor immunosurveillance and worse patient outcomes. B7-H4 can serve as a novel prognostic predictor for human ESCC and a potential target for the immune therapy against this malignancy.

No abstract

Trastuzumab shows remarkable efficacy in treatment of ErbB2-positive breast cancers when used alone or in combination with other chemotherapeutics. However, acquired resistance develops in most treated patients, necessitating alternate treatment strategies. Increased aerobic glycolysis is a hallmark of cancer and inhibition of glycolysis may offer a promising strategy to preferentially kill cancer cells. In this study, we investigated the antitumor effects of trastuzumab in combination with glycolysis inhibitors in ErbB2-positive breast cancer. We found that trastuzumab inhibits glycolysis via downregulation of heat shock factor 1 (HSF1) and lactate dehydrogenase A (LDH-A) in ErbB2-positive cancer cells, resulting in tumor growth inhibition. Moreover, increased glycolysis via HSF1 and LDH-A contributes to trastuzumab resistance. Importantly, we found that combining trastuzumab with glycolysis inhibition synergistically inhibited trastuzumab-sensitive and -resistant breast cancers in vitro and in vivo, due to more efficient inhibition of glycolysis. Taken together, our findings show how glycolysis inhibition can dramatically enhance the therapeutic efficacy of trastuzumab in ErbB2-positive breast cancers, potentially useful as a strategy to overcome trastuzumab resistance.

Molecular defects affecting tumor-suppressor genes are an important step in the genesis of sarcomas. For example, inheritance of a defective Rb or p53 gene predisposes the carrier to develop osteosarcoma, among other malignancies. In this study, we have assessed the occurrence of p53, Rb and MDM2 alterations in the same samples of osteosarcomas, along with representative samples of various other sarcomas. Point mutations of the p53 gene were found in 13 of 42 osteosarcomas and 1 of 8 leiomyosarcomas, and gross rearrangement of the p53 gene was demonstrated in 5 of 37 osteosarcomas. The retinoblastoma susceptibility gene (Rb) was either rearranged or deleted in 7 of 37 osteosarcomas, 1 of 7 soft-tissue sarcomas and 1 of 4 Ewing sarcomas. Remarkably, 5 of the osteosarcomas having Rb alterations also had p53 mutations. Amplification and overexpression of the MDM2 oncogene may lead to increased MDM2-p53 binding resulting in inactivation of p53 function. A two- to threefold increase in the copy number of MDM2 was detected in 7 of 37 samples, 5 of which were osteosarcomas. Amplification of the MDM2 gene occurred independently of p53 mutation; one sample having threefold amplification of MDM2 also had a p53 mutation. In summary, 34 alterations of the p53, Rb and MDM2 genes were found in 26 of 42 (62%) osteosarcomas.

Adipose tissue secretes adipocytokines for energy homeostasis, but recent evidence indicates that some adipocytokines also have a profound local impact on wound healing. Upon skin injury, keratinocytes use various signaling molecules to promote reepithelialization for efficient wound closure. In this study, we identify a novel function of adipocytokine angiopoietin-like 4 (ANGPTL4) in keratinocytes during wound healing through the control of both integrin-mediated signaling and internalization. Using two different in vivo models based on topical immuno-neutralization of ANGPTL4 as well as ablation of the ANGPTL4 gene, we show that ANGPTL4-deficient mice exhibit delayed wound reepithelialization with impaired keratinocyte migration. Human keratinocytes in which endogenous ANGPTL4 expression was suppressed by either siRNA or a neutralizing antibody show impaired migration associated with diminished integrin-mediated signaling. Importantly, we identify integrins ␤1 and ␤5, but not ␤3, as novel binding partners of AN-GPTL4. ANGPTL4-bound integrin ␤1 activated the FAKSrc-PAK1 signaling pathway, which is important for cell migration. The findings presented herein reveal an unpredicted role of ANGPTL4 during wound healing and demonstrate how ANGPTL4 stimulates intracellular signaling mechanisms to coordinate cellular behavior. Our findings provide insight into a novel cell migration control mechanism and underscore the physiological importance of the modulation of integrin activity in cancer metastasis.

Angiopoietin-like 4 (ANGPTL4) is best known for its role as an adipokine involved in the regulation of lipid and glucose metabolism. The characterization of ANGPTL4 as an adipokine is largely due to our limited understanding of the interaction partners of ANGPTL4 and how ANGPTL4 initiates intracellular signaling. Recent findings have revealed a critical role for ANGPTL4 in cancer growth and progression, anoikis resistance, altered redox regulation, angiogenesis, and metastasis. Emerging evidence suggests that ANGPTL4 function may be drastically altered depending on the proteolytic processing and posttranslational modifications of ANGPTL4, which may clarify several conflicting roles of ANGPTL4 in different cancers. Although the N-terminal coiled-coil region of ANGPTL4 has been largely responsible for the endocrine regulatory role in lipid metabolism, insulin sensitivity, and glucose homeostasis, it has now emerged that the COOH-terminal fibrinogen-like domain of ANGPTL4 may be a key regulator in the multifaceted signaling during cancer development. New insights into the mechanistic action of this functional domain have opened a new chapter into the possible clinical application of ANGPTL4 as a promising candidate for clinical intervention in the fight against cancer. This review summarizes our current understanding of ANGPTL4 in cancer and highlights areas that warrant further investigation. A better understanding of the underlying cellular and molecular mechanisms of ANGPTL4 will reveal novel insights into other aspects of tumorigenesis and the potential therapeutic value of ANGPTL4. Mol Cancer Res; 10(6); 677-88. Ó2012 AACR.