Tumour-suppressive microRNA-29s directly regulate LOXL2 expression and inhibit cancer cell migration and invasion in renal cell carcinoma
FEBS LETTERS
Authors: Nishikawa, Rika; Chiyomaru, Takeshi; Enokida, Hideki; Inoguchi, Satoru; Ishihara, Tomoaki; Matsushita, Ryosuke; Goto, Yusuke; Fukumoto, Ichiro; Nakagawa, Masayuki; Seki, Naohiko
Abstract
Here, we found that members of the microRNA-29 family (miR-29a/b/c; "miR-29s") were significantly reduced in clear cell renal cell carcinoma (ccRCC) tissues, suggesting that they functioned as tumour suppressors. Restoration of all mature members of the miR-29 family inhibited cancer cell proliferation, migration and invasion. LOXL2 was a direct target gene of miR-29s, as shown by genome-wide gene expression analysis and luciferase reporter assay. Overexpressed LOXL2 was confirmed in ccRCC clinical specimens, and silencing of LOXL2 inhibited cancer cell migration and invasion in ccRCC cell lines. Our data demonstrated that the miR-29s-LOXL2 axis contributed to cancer cell migration and invasion in ccRCC. (C) 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
The Enzymatic Activity of Lysyl Oxidas-like-2 (LOXL2) Is Not Required for LOXL2-induced Inhibition of Keratinocyte Differentiation
JOURNAL OF BIOLOGICAL CHEMISTRY
Authors: Lugassy, Jennie; Zaffryar-Eilot, Shelly; Soueid, Sharon; Mordoviz, Amit; Smith, Victoria; Kessler, Ofra; Neufeld, Gera
Abstract
Lysyl oxidase-like-2 (LOXL2) induces tumor progression and fibrosis. It also inhibits the differentiation of keratinocytes promoting development of squamous cell carcinomas. Stimulation of HaCaT skin keratinocytes with exogenous LOXL2 or overexpression of LOXL2 in these cells inhibits their differentiation as manifested by inhibition of calcium or vitamin D-induced involucrin expression. The inhibition was abrogated by the LOXL2 function-blocking monoclonal antibody AB0023 as well as by an anti-LOXL2 polyclonal antibody. Surprisingly, a point-mutated form of LOXL2 (LOXL2(Y689F)) lacking enzymatic activity, as well as a LOXL2 deletion mutant lacking the entire catalytic domain, also inhibited calcium or vitamin D-induced up-regulation of involucrin expression, suggesting that the enzymatic activity of LOXL2 is not required for this activity. This conclusion was supported by experiments that showed that beta-aminoproprionitrile, an irreversible competitive inhibitor of the enzymatic activity of all lysyl oxidases, is unable to abolish the LOXL2-induced inhibition of HaCaT cell differentiation. The activity of LOXL2(Y689F) required the presence of the fourth scavenger receptor-cysteine-rich (SRCR) domain of LOXL2, which is also the binding target of AB0023. Epitope-tagged LOXL2(Y689F) was internalized at 37 degrees C by HaCaT cells. The internalization was inhibited by AB0023 and by competition with unlabeled LOXL2, suggesting that these cells may express a LOXL2 receptor. Our results suggest that agents that inhibit the enzymatic activity of LOXL2 may not suffice to inhibit completely the effects of LOXL2 on complex processes that involve altered states of cellular differentiation.