Lysyl oxidase-like-2 promotes tumour angiogenesis and is a potential therapeutic target in angiogenic tumours

Abstract

Lysyl oxidase-like 2 (LOXL2), a secreted enzyme that catalyzes the cross-linking of collagen, plays an essential role in developmental angiogenesis. We found that administration of the LOXL2-neutralizing antibody AB0023 inhibited bFGF-induced angiogenesis in Matrigel plug assays and suppressed recruitment of angiogenesis promoting bone marrow cells. Small hairpin RNA-mediated inhibition of LOXL2 expression or inhibition of LOXL2 using AB0023 reduced the migration and network-forming ability of endothelial cells, suggesting that the inhibition of angiogenesis results from a direct effect on endothelial cells. To examine the effects of AB0023 on tumour angiogenesis, AB0023 was administered to mice bearing tumours derived from SKOV-3 ovarian carcinoma or Lewis lung carcinoma (LLC) cells. AB0023 treatment significantly reduced the microvascular density in these tumours but did not inhibit tumour growth. However, treatment of mice bearing SKOV-3-derived tumours with AB0023 also promoted increased coverage of tumour vessels with pericytes and reduced tumour hypoxia, providing evidence that anti-LOXL2 therapy results in the normalization of tumour blood vessels. In agreement with these data, treatment of mice bearing LLC-derived tumours with AB0023 improved the perfusion of the tumour-associated vessels as determined by ultrasonography. Improved perfusion and normalization of tumour vessels after treatment with anti-angiogenic agents were previously found to improve the delivery of chemotherapeutic agents into tumours and to result in an enhancement of chemotherapeutic efficiency. Indeed, treatment with AB0023 significantly enhanced the anti-tumourigenic effects of taxol. Our results suggest that inhibition of LOXL2 may prove beneficial for the treatment of angiogenic tumours.

Tumor Cell Invasion Can Be Blocked by Modulators of Collagen Fibril Alignment That Control Assembly of the Extracellular Matrix

“…The HDF cells were incubated with 0.4% Triton, 1.5 mol/L NaCl, 50 mmol/L Tris pH 8, and 50 mmol/L EDTA for 48 hours in 4 C, washed gently with water, incubated with 0.5% sodium deoxycholate for 1 hour at 25 C, and finally with PBS (þMgCl 2 ) and 100 ngr/mL DNase at 37 C for 1 hour to remove DNA contamination.…”

“…In addition, overexpression of these enzymes in cancer has been correlated with distinct events during tumor progression. LOXL2 is highly overexpressed in invasive metastatic tumors compared with noninvasive ones (12) and is linked to promoting tumor cell invasion and angiogenesis (18,25). However, the exact molecular mechanisms by which these enzyme execute their enzymatic activities and how they contribute to tumor malignancy is not fully understood, mainly due to the complexity of ECM molecules and the technical challenges associated with structurally characterizing these molecules in high resolution.…”

Lysyl oxidases: emerging promoters of senescence escape, tumor initiation and progression

“…This complex mechanism involves proliferation and migration of endothelial cells and remodeling of the basal membrane of blood vessels [27] and is coordinated by LOX and LOXL2. This has been reported in various models including using a zebrafish model during capillary formation [28] and in various tumor xenograft models in mice [29,30] . LOX and LOXL2 might impact angiogenesis by regulating endothelial cell proliferation and migration by collagen assembly and scaffolding [28] and by impacting the production of VEGF [30] .…”

Stroma as an Active Player in the Development of the Tumor Microenvironment

“…An example of LOX family deregulated activity has been documented for LOXL2. Remodeling of ECM promoted by LOXL2 was found to be associated with regulation of epithelial-to-mesenchymal transition, epithelial cell polarity and differentiation mediated by transcriptional repression mechanisms [51], sprouting angiogenesis by modulation of type IV collagen assembly in endothelial basement membrane [52] and fibroblast activation [53]. LOX and LOXL2 resulted in being regulated by hypoxia, with a relevant role in hypoxia-induced metastases [54].…”