Dysregulation of Ezrin Phosphorylation Prevents Metastasis and Alters Cellular Metabolism in Osteosarcoma

Abstract

Ezrin links the plasma membrane to the actin cytoskeleton where it plays a pivotal role in the metastatic progression of several human cancers (1, 2), however, the precise mechanistic basis for its role remains unknown. Here we define transitions between active (phosphorylated open) and inactive (dephosphorylated closed) forms of Ezrin that occur during metastatic progression in osteosarcoma. In our evaluation of these conformations we expressed C-terminal mutant forms of Ezrin that are open (phosphomimetic T567D) or closed (phosphodeficient T567A) and compared their biological characteristics to full length wild-type Ezrin in osteosarcoma cells. Unexpectedly, cells expressing open, active Ezrin could form neither primary orthotopic tumors nor lung metastases. In contrast, cells expressing closed, inactive Ezrin were also deficient in metastasis but were unaffected in their capacity for primary tumor growth. By imaging single metastatic cells in the lung, we found that cells expressing either open or closed Ezrin displayed increased levels of apoptosis early after their arrival in the lung. Gene expression analysis suggested dysregulation of genes that are functionally linked to carbohydrate and amino acid metabolism. In particular, cells expressing closed, inactive Ezrin exhibited reduced lactate production and basal or ATP-dependent oxygen consumption. Collectively, our results suggest that dynamic regulation of Ezrin phosphorylation at amino acid T567 that controls structural transitions of this protein plays a pivotal role in tumor progression and metastasis, possibly in part by altering cellular metabolism.

Bioinformatics Analyses of m-RNA Profiling Following Ezrin Knockdown in Esophageal Squamous Cell Carcinoma

“…One of the advantages of the subpathway method is that it identifies more pathways than the traditional pathway enrichment. Using SubpathwayMiner, we found several metabolismrelated subpathways for the DEGs in this study, supporting recent findings about the relationship between Ezrin and cellular metabolism [26]. Ren et al found differentially expressed genes that obtained from mutant Ezrin overexpression in osteosarcoma were functionally linked to carbohydrate and amino acid metabolism.…”

“…Ren et al found differentially expressed genes that obtained from mutant Ezrin overexpression in osteosarcoma were functionally linked to carbohydrate and amino acid metabolism. In particular, cells expressing closed, inactive Ezrin exhibited reduced lactate production and basal or ATP-dependent oxygen consumption [26]. It suggests that the correlation between Ezrin and metabolism might be a common phenomenon in different cell type of cancers.…”

Ezrin Inhibition Up-regulates Stress Response Gene Expression

“…Disseminated metastatic cells encounter various microenvironmental stresses in the circulation or after reaching a new environment where they must adapt and endure these stresses to survive and establish secondary tumors (33,34). Studies using human and mouse osteosarcoma cells expressing inactive ezrin demonstrated that dysregulation of ezrin function results in a consistent increase in apoptosis of cells early after their arrival in the lung with no effect on the growth of primary tumor (35). In the present study, the comparison of global gene expression changes in response to NSC305787 and NSC668394 treatment indicated a common transcriptional regulation of genes with functional relevance to integrated stress response, suggesting a specific ezrin-mediated response in both human and mouse osteosarcoma cells (Table 4).…”

Protein phosphatase 2A Cα regulates proliferation, migration, and metastasis of osteosarcoma cells

“…It was demonstrated that low metastatic tumor cells have lower oxygen consumption than high metastatic tumors, including osteosarcoma. 30,31 Although many studies reported a shift from oxidative phosphorylation to glycolysis to provide energy for cellular activities in cancer cells, 32 cancer cells have also been reported to rely on oxidative phosphorylation and mitochondrial bioenergetics pathways for anabolism and energy production. 33 Our present finding indicates that PP2A Cα is involved in the regulation of mitochondrial respiratory capacity.…”