Lysyl oxidase-like 2 (LOXL2), a new regulator of cell polarity required for metastatic dissemination of basal-like breast carcinomas.
Bottom Line: 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.
Affiliation: Departamento de Bioquímica, UAM, Instituto de Investigaciones Biomédicas "Alberto Sols", CSIC-UAM, IdiPAZ, Instituto de Investigación Sanitaria La Paz, Madrid, Spain. firstname.lastname@example.orgShow MeSH
Related in: MedlinePlus
Mentions: To ascertain whether the marked effect of LOXL2 silencing on the phenotype and migratory capacity was restricted to MDA-MB-231 cells or rather represents a general effect on basal cells, stable knockdown of LOXL2 was also performed in BT549 and HBL100 basal cell lines (Supporting Information Fig S3B). Again, LOXL2 silencing in both of these cell lines resulted in a marked reversion towards the epithelial phenotype that was particularly evident in high density cultures of BT549-shLOXL2 cells (Supporting Information Fig S3C). LOXL2 silencing also led to a dramatic inhibition of cell motility in BT549 and HBL100 cells (Supporting Information Fig S3D and E) and suppression of invasiveness in BT549 cells (Supporting Information Fig S4C). Noteworthy, no re-expression of E-cadherin was detected in BT549 or HBL100 cells after LOXL2 silencing (Supporting Information Fig S3B), but BT549-shLOXL2 cells maintained noticeable N-cadherin and cadherin11 levels (Supporting Information Fig S4A). Moreover, BT549 cells do not express endogenous Snail1 and remained unchanged after LOXL2 silencing (Supporting Information Fig S4A). In addition, reorganization of F-actin and downregulation of vimentin is observed after LOXL2 silencing in BT549 cells (Supporting Information Fig S4B). These results indicate that LOXL2 silencing induces a MET-like process in basal cell lines associated with decreased invasive and migratory properties. They are also in concordance with our previous observation and those by other groups showing that ectopic expression of LOXL2 in luminal MCF7 cells induces a mesenchymal-like phenotype and migratory and invasive potential (Fig 3B; Akiri et al, 2003; Hollosi et al, 2009). The present results support that LOXL2 is involved in the maintenance of the mesenchymal phenotype in basal carcinoma cells.
Affiliation: Departamento de Bioquímica, UAM, Instituto de Investigaciones Biomédicas "Alberto Sols", CSIC-UAM, IdiPAZ, Instituto de Investigación Sanitaria La Paz, Madrid, Spain. email@example.com