LOXL2 upregulates hypoxia-inducible factor-1 alpha signaling through Snail-FBP1 axis in hepatocellular carcinoma cells
ONCOLOGY REPORTS
Authors: Fan, Zhiyong; Zheng, Wei; Li, Hui; Wu, Wujun; Liu, Xiaogang; Sun, Zhongjie; Hu, Haitian; Du, Lixue; Jia, Qingan; Liu, Qingguang
Abstract
Lysyl oxidase-like 2 (LOXL2), a member of the lysyl oxidase gene family, is involved in the progression of hepatocellular carcinoma progression and metastasis. Increased expression of LOXL2 has been identified in several types of cancer, including hepatocellular carcinoma. Recently, LOXL2 has been reported to promote epithelial-mesenchymal transition by reducing E-cadherin expression via the upregulation of Snail expression. The present study provided evidence demonstrating that LOXL2 inhibited the expression of fructose-1, 6-biphosphatase (FBP1) and enhanced the glycolysis of Huh7 and Hep3B hepatocellular carcinoma cell lines in a Snail-dependent manner. Overexpression of the point-mutated form of LOXL2 [LOXL2(Y689F)], which lacks enzymatic activity, does not affect the expression of Snail1 or FBP1. Notably, targeting extracellular LOXL2 of Huh7 cells with a therapeutic antibody was unable to abolish its regulation on the expression of Snail and FBP1. Knockdown of LOXL2 also interrupted the angiogenesis of Huh7 and Hep3B cells, and this effect could be rescued by the overexpression of Snail. Furthermore, upregulation of hypoxia-inducible factor 1 alpha (HIF-1 alpha) and vascular endothelial growth factor (VEGF) expression was observed in Huh7 and Hep3B cells expressing wild-type LOXL2. Notably, the selective LOXL2 inhibitor LOXL2-IN-1 could upregulate the expression of FBP1 and inhibit the expression of Snail, HIF-1 alpha and VEGF in HCC cells, but not in FBP1-knockdown cells. The results of the present study indicated that the intracellular activity of LOXL2 upregulated HIF-1 alpha/VEGF signaling pathways via the Snail-FBP1 axis, and this phenomenon could be inhibited by LOXL2 inhibition. Collectively, these findings further support that LOXL2 exhibits an important role in the progression of hepatocellular carcinoma and implicates LOXL2 as a potential therapeutic agent for the treatment of this disease.
Lysyl oxidase-like 2 (LOXL2), a new regulator of cell polarity required for metastatic dissemination of basal-like breast carcinomas
EMBO MOLECULAR MEDICINE
Authors: Moreno-Bueno, Gema; Salvador, Fernando; Martin, Alberto; Floristan, Alfredo; Cuevas, Eva P.; Santos, Vanesa; Montes, Amalia; Morales, Saleta; Angeles Castilla, Maria; Rojo-Sebastian, Alejandro; Martinez, Alejandra; Hardisson, David; Csiszar, Katalin; Portillo, Francisco; Peinado, Hector; Palacios, Jose; Cano, Amparo
Abstract
Basal-like breast carcinoma is characterized by the expression of basal/myoepithelial markers, undifferentiated phenotype, highly aggressive behaviour and frequent triple negative status (ESR-, PR-, Her2neu-). We have previously shown that epithelial mesenchymal transition (EMT) occurs in basal-like breast tumours and identified Lysyl-oxidase-like 2 (LOXL2) as an EMT player and poor prognosis marker in squamous cell carcinomas. We now show that LOXL2 mRNA is overexpressed in basal-like human breast carcinomas. Breast carcinoma cell lines with basal-like phenotype show a specific cytoplasmic/perinuclear LOXL2 expression, and this subcellular distribution is significantly associated with distant metastatic incidence in basal-like breast carcinomas. LOXL2 silencing in basal-like carcinoma cells induces a mesenchymal-epithelial transition (MET) associated with a decrease of tumourigenicity and suppression of metastatic potential. Mechanistic studies indicate that LOXL2 maintains the mesenchymal phenotype of basal-like carcinoma cells by a novel mechanism involving transcriptional downregulation of Lgl2 and claudin1 and disorganization of cell polarity and tight junction complexes. Therefore, intracellular LOXL2 is a new candidate marker of basal-like carcinomas and a target to block metastatic dissemination of this aggressive breast tumour subtype.