Estudo do envolvimento da metalo-peptidase PHEX em processos tumorais

• Autor(a) principal: Neves, Raquel Leao [UNIFESP]
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UNIFESP
• Texto Completo: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=6316793; https://repositorio.unifesp.br/handle/11600/53041
• topic: Phex; Xlh; Squamous cell carcinoma,; Osteopontina; Tumor; Squamous cell carcinoma; Osteopontin; Tumor

Mutations in PHEX gene result in a prevalent (1: 20,000) form of hereditary human rickets, the XLinked Hypophosphataemia (XLH). XLH is characterized by deficiency in phosphate reabsorption and vitamin D metabolism, and defects in bone mineralization. Using several methodologies and the murine XLH model, we identified the OPN (osteopontin) as the first PHEX physiological substrate. OPN is a multifunctional phosphoglycoprotein with tissuespecific activities that, among its functions, can act in bone as a potent inhibitor of bone mineralization, and in tumors, as a promoter of tumor progression. Considering these data, we extended our studies of this protease in head and neck squamous cell carcinoma (HNSCC). In the present work, we demonstrate for the first time the high expression of PHEX in nonbone tumor cells (SCC22B), and describe the modulation of tumor OPN (SCC22BOPN) by exogenous PHEX and characterize the temporal targeting of the PHEX protein to SCC22B cell membrane. We have found that cysteine proteases expressed in these cells can degrade/inactivate endogenous PHEX and the treatment of these cells with the E64 inhibitor results in increased of PHEX in membrane and the degradation of OPN tumor fragments (SCC22BOPN). To better understand the role of PHEX in SCC22B cells, proliferation and migration assays were performed using the wound healing method in two different SCC22B cell models constructed in our laboratory, SCC22B shRNAPHEX (reduced PHEX gene expression) and SCC22B secPHEX (overexpression of the secreted form of PHEX). The analyzes performed indicated that when compared to SCC22B, the SCC22B secPHEX cell lineage showed reduction in cell proliferation and migration, whereas a considerable increase was observed in SCC22B shRNAPHEX cells. In addition to these two models, recently we have also developed a third line that overexpresses PHEX with the integral transmembrane domain (SCC22B mbPHEX) and is being characterized by our group. Finally, using the Jurkat, Kasumi, KG1, K562 and Lucena cell lineages, we also demonstrated the expression of PHEX/PHEX in leukemia cells (nonsolid tumors). The results obtained represent an advance in the functional characterization of PHEX, and demonstrate that its expression and/or function are not restricted only to mineralized tissues.