Abstract B22: Uncovering the role of lysyl oxidase-like 2 in rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft-tissue malignancy in childhood and adolescence that originates as a consequence of regulatory disruption in the growth and differentiation of muscle precursor cells. Members of the lysyl oxidase family of proteins (LOX and LOXL1-4) are amine oxidases that catalyze the covalent crosslinking of collagen and elastin in the extracellular matrix. Apart from their traditional role, novel functions have been attributed to these proteins related to tumor progression. In this study we sought to unravel the potential role of this family of proteins during the progression of RMS. By qRT-PCR and Western blot, lysyl oxidase-like 2 (LOXL2) was found overexpressed in RMS cell lines compared to other sarcoma cells. Then we characterized LOXL2 in RMS cell lines by analyzing the subcellular localization by immunofluorescence and subcellular fractionation. Post-translational modifications were also analyzed: glycosylation and proteolytic processing by tunicamycin treatment and secretion by analysis of the conditioned media by Western blot. Moreover, we characterized the neoplastic phenotype after silencing LOXL2 in two RMS cell lines (RH4 and CW9019). Stable LOXL2 knockdown resulted in a decrease in their clonogenic, proliferative, and cell migratory capabilities. On the other hand, reexpression of LOXL2 in RH28 cells using wild-type or mutated (catalytically inactive) constructs resulted in an increase in cell proliferation and migration, independently of its catalytic activity. Finally, in vivo experiments using an orthotopic model of tumor generation inside the muscle will be carried out to further evaluate the tumorigenic role of LOXL2. Taking all into consideration, our results suggest an oncogenic role of LOXL2 in RMS. Citation Format: Olga Almacellas Rabaiget, Juan Huertas Martínez, Silvia Garcia Monclús, Santiago Rello Varona, David Herrero Martín, Roser López Alemany, Oscar M. Tirado. Uncovering the role of lysyl oxidase-like 2 in rhabdomyosarcoma [abstract]. In: Proceedings of the AACR Conference on Advances in Sarcomas: From Basic Science to Clinical Translation; May 16-19, 2017; Philadelphia, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(2_Suppl):Abstract nr B22.