Phosphorylated Ezrin Is Located in the Nucleus of the Osteosarcoma Cell In Vitro and In Vivo
C Di Cristofano, M Leopizzi, A Miraglia, B Sardella, V Moretti, A Ferrara, V Petrozza, C Della Rocca. Sapienza University of Rome, Polo Pontino, I.C.O.T., Latina, Italy
Background: The survival of osteosarcoma patients is connected to metastasis. The ezrin expression was 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. The study evaluated ezrin and phosphorylated ezrin (p-ezrinTyr354 and p-ezrinThr567) expression and its sub-cellular localization in osteosarcoma.
Design: We studied 50 osteosarcoma patients (mean follow-up 9,8 yrs). Ezrin expression were assessed using immunohistochemistry (IHC) and immunofluorescence (IF) analysis on tissue microarray (TMA) and cultured cells of human osteosarcoma (143B). The Western Blot (WB) analysis was performed on 143B.
Results: The majority of osteosarcomas, shown cytoplasmic positivity for ezrin, phosphorylated and un-phosphorylated, were associated with membranous and nuclear positivity for p-ezrinThr567 and p-ezrinTyr354 respectively. The IF and WB analysis confirmed the nuclear localization of p-ezrinTyr354. Ezrin expression was associated with high grade osteosarcoma (p=0,04), with metastasis (p=0,04) and with tumors that developed metastasis (p=0,04); p-ezrinThr567 expression was present mostly in tumors with respect to metastasis (p=0,01) and in osteosarcomas that didn't develop metastasis (p=0,002). The osteosarcoma patients with ezrin expression have a short survival.
Conclusions: The cytoplasmic ezrin expression matches with its role of membrane-cytoskeleton linker protein, also in osteosarcoma. The p-ezrinTyr354 nuclear localization suggests its possible role as a nuclear factor in osteosarcoma. The ezrinThr567 phosphorylation may not be necessary in osteosarcoma metastatic progression but it was modulated. The ezrin expression is associated with a more aggressive osteosarcomas and with the metastatic process.
Category: Bone & Soft Tissue
Tuesday, March 23, 2010 9:30 AM
Poster Session III # 27, Tuesday Morning