The LPA1/ZEB1/miR-21-activation pathway regulates metastasis in basal breast cancer

// Debashish Sahay 1 , Raphael Leblanc 1 , Thomas G. P. Grunewald 2 , Srikant Ambatipudi 3 , Johnny Ribeiro 1 , Philippe Clézardin 1 , Olivier Peyruchaud 1 1 INSERM, UMR1033, UCB Lyon 1, Faculté de Médecine Lyon Est, Lyon, France 2 Laboratory for Pediatric Sarcoma Biology, Institute of Pathology, LMU Munich, Munich, Germany 3 Epigenetics Group, International Agency for Research on Cancer, Lyon, France Correspondence to: Olivier Peyruchaud, e-mail: olivier.peyruchaud@inserm.fr Keywords: lysophosphatidic acid, ZEB1, miR-21, breast cancer, metastasis Received: March 03, 2015 Accepted: April 15, 2015 Published: April 27, 2015 ABSTRACT Lysophosphatidic acid (LPA) is a bioactive lipid promoting cancer metastasis. LPA activates a series of six G protein-coupled receptors (LPA 1-6 ). While blockage of LPA 1 in vivo inhibits breast carcinoma metastasis, down-stream genes mediating LPA-induced metastasis have not been yet identified. Herein we showed by analyzing publicly available expression data from 1488 human primary breast tumors that the gene encoding the transcription factor ZEB1 was the most correlated with LPAR1 encoding LPA 1 . This correlation was most prominent in basal primary breast carcinomas and restricted to cell lines of basal subtypes. Functional experiments in three different basal cell lines revealed that LPA-induced ZEB1 expression was regulated by the LPA 1 /Phosphatidylinositol-3-Kinase (Pi3K) axis. DNA microarray and real-time PCR analyses further demonstrated that LPA up-regulated the oncomiR miR-21 through an LPA 1 /Pi3K/ZEB1-dependent mechanism. Strikingly, treatment with a mirVana miR-21 inhibitor, or silencing LPA 1 or ZEB1 completely blocked LPA-induced cell migration in vitro , invasion and tumor cell bone colonization in vivo , which can be restored with a mirVana miR-21 mimic. Finally, high LPAR1 expression in basal breast tumors predicted worse lung-metastasis-free survival. Collectively, our results elucidate a new molecular pathway driving LPA-induced metastasis, thus underscoring the therapeutic potential of targeting LPA 1 in patients with basal breast carcinomas.