Phosphorylated ezrin is located in the nucleus of the osteosarcoma cell

Abstract

The survival of osteosarcoma patients is connected to metastasis. The ezrin expression is associated with the development of metastasis and poor outcome in osteosarcoma. Ezrin is present in the cytoplasm and after phosphorylation assumes an active form and links F-actin to the cell membrane. This study evaluated ezrin and phosphorylated ezrin at site Tyr354 and Thr567 expression and its subcellular localization in osteosarcoma. We studied 50 osteosarcoma patients (mean follow-up 9.8 years). Ezrin expression was assessed using immunohistochemical and immunofluorescence analysis on tissue microarray and cultured cells of human osteosarcoma 143B. The western blot analysis was carried out on cultured cells. The majority of osteosarcomas, showing cytoplasmic positivity for ezrin, phosphorylated and unphosphorylated, were associated with membranous and nuclear positivity for phosphorylated ezrin Thr567 and phosphorylated ezrin Tyr354, respectively. Ezrin expression was associated with high-grade osteosarcoma (P ¼ 0.04), with metastasis (P ¼ 0.04) and with tumors that developed metastasis (P ¼ 0.04); phosphorylated ezrin Thr567 expression was present mostly in tumors with metastasis (P ¼ 0.01) and in osteosarcomas that did not develop metastasis (P ¼ 0.002). The osteosarcoma patients with ezrin expression have a short survival. The cytoplasmic ezrin expression in osteosarcoma matches its role of membrane-cytoskeleton linker protein. The subcellular trafficking of ezrin is not blocked and it is linked to ezrin phosphorylation, also in cancer. The phosphorylated ezrin Tyr354 nuclear localization suggests its possible role as a nuclear factor in osteosarcoma. The phosphorylated ezrin Thr567 phosphorylation may not be necessary in osteosarcoma metastatic progression but it was modulated. The ezrin expression is associated with more aggressive osteosarcomas and with metastasis.

Ezrin silencing remodulates the expression of Phosphoinositide‐specific Phospholipase C enzymes in human osteosarcoma cell lines

“…ERM proteins bind actin and, by means of their N-terminal domains, simultaneously the PIP2 located at the plasma membrane (Niggli, V et al 2008, Gilmore and Burridge 1996Isenberg and Niggli 1998, Nakamura et al 1999, Eberle et al 1990, Dobos et al 1992, Apgar 1995, Gachet et al 1997, Gratacap et al 1998. Once activated, Ezrin, commonly localized in the cytoplasm in its inactive form, moves and tethers actin to the cortical membrane, thus promoting cytoskeleton reorganization and subsequent cell morphology alterations (Dard et al 2004;Zhu et al 2007;Di Cristofano et al 2010;Yang et al 2012;Zhao et al 2011;Tan and Yang 2010). Beside phosphorylation, activation of ERM proteins also occurs after interaction with PIP2 (Gilmore and Burridge 1996, Hirao et al 1996, Legg and Isacke 1998, Nakamura et al 1999.…”

Phosphorylated T567 ezrin is associated with merlin expression in KIT-mutant gastrointestinal stromal tumors

“…This finding was supported by Di Cristofano et al and Cui et al who evaluated p-ezrinTyr353 and p-ezrinThr567 expression in osteosarcoma and pancreatic ductal adenocarcinoma, respectively, and pinpointed that p-ezrinThr567 expression could be observed mostly in tumors and related to tumor progression. However, there is no strong evidence supporting the promotion of tumor metastatis (41,42).…”

Ezrin expression and its phosphorylation in gastric carcinoma with lymphoid stroma and Epstein-Barr virus infection

“…In the present study, anti-ezrin unphosphorylated type and anti-ERM [ezrin (Thr567)/radixin (Thr564)/moesin (Thr558), Cell Signaling Technology, Inc.] antibody was used as the anti-ezrin phosphorylated form at the Thr567 site, also used as the p-ezrin antibody at Thr567 in previously published studies (26,27). The phosphorylation of residual Thr567 in ezrin alters the protein to expose its binding sites (28) thus resulting in oncogene-induced transformation (29).…”