Role of Ezrin in Osteosarcoma Metastasis

Abstract

The cause of death for the vast majority of cancer patients is the development of metastases at sites distant from that of the primary tumor. For most pediatric sarcoma patients such as those with osteosarcoma (OS), despite successful management of the primary tumor through multimodality approaches, the development of metastases, commonly to the lungs, is the cause of death. Significant improvements in long-term outcome for these patients have not been seen in more than 30 years. Furthermore, the long-term outcome for patients who present with metastatic disease is grave [1-5]. New treatment options are needed.Opportunities to improve outcomes for patients who present with metastases and those at-risk for progression and metastasis require an improved understanding of cancer progression and metastasis. With this goal in mind we and others have identified ezrin as a metastasis-associated protein that associated with OS and other cancers. Ezrin is the prototypical ERM (Ezrin/Radixin/Moesin) protein family member. ERMs function as linker proteins connecting the actin cytoskeleton and the plasma membrane. Since our initial identification of ezrin in pediatric sarcoma, an increasing understanding the role of ezrin in metastasis has emerged. Briefly, ezrin appears to allow metastatic cells to overcome a number of stresses experienced during the metastatic cascade, most notably the stress experienced as cells interact with the microenvironment of the secondary site. Cells must rapidly adapt to this environment in order to survive. Evidence now suggests a connection between ezrin expression and a variety of mechanisms linked to this important cellular adaptation including the ability of metastatic cells to initiate the translation of new proteins and to allow the efficient generation of ATP through a variety of sources. This understanding of the role of ezrin in the biology of metastasis is now sufficient to consider ezrin as an important therapeutic target in osteosarcoma patients. This chapter reviews our understanding of ezrin and the related ERM proteins in normal tissues and physiology, summarizes the expression of ezrin in human cancers and associations with clinical parameters of disease progression, reviews reports that detail a biological understanding of ezrin's role in metastatic progression, and concludes with a rationale that may be considered to target ezrin and ezrin biology in osteosarcoma.

The clinical significance of changes in ezrin expression in osteosarcoma of children and young adults

“…In our opinion, it is important to understand the role of ezrin in the biology of osteosarcoma metastasis because ezrin could become the meaningful therapeutic target for osteosarcoma and other cancers [13,36]. Shang et al [37] designed three siRNAs targeting ezrin mRNA, which downregulated the expression level of ezrin mRNA and protein, inhibited cellular proliferation, and effectively promoted cellular apoptosis.…”

Ezrin Inhibition Up-regulates Stress Response Gene Expression

“…Translation of biological knowledge into clinical practice remains challenging because there is currently a lack of anti-metastatic compounds specifically targeting metastatic regulators (30,31). Ezrin has been validated as a key determinant in the development of metastatic osteosarcoma, which supports the development of small molecule ezrin inhibitors (12,19). Ezrin is involved in all phases of metastasis including invasion, motility, and survival in a new environment, thereby highlighting its importance as a key therapeutic target in cancer (32).…”

“…A high level of ezrin is associated with a poor prognosis in pediatric osteosarcoma patients and in spontaneous canine osteosarcomas (12,19). Ezrin directly increases the metastatic capability of osteosarcoma cells by providing an early survival advantage for cancer cells reaching the lung in a mouse model (12,19). Therefore, development of novel tar-geted therapeutics that effectively inhibit ezrin to prevent pulmonary metastasis is urgently needed.…”

“…The development of metastasis, commonly to the lungs, remains the major cause of death in osteosarcoma patients (18). A high level of ezrin is associated with a poor prognosis in pediatric osteosarcoma patients and in spontaneous canine osteosarcomas (12,19). Ezrin directly increases the metastatic capability of osteosarcoma cells by providing an early survival advantage for cancer cells reaching the lung in a mouse model (12,19).…”

Baicalein Inhibits Proliferation Activity of Human Colorectal Cancer Cells HCT116 Through Downregulation of Ezrin

“…The ERM protein family contains a series of linking proteins which function in connecting the actin cytoskeleton and the plasma membrane [13]. Increasing researches focus on the role of Ezrin in cancer invasion and metastasis since its initial identification.…”