ABSTRACT
CRIPTO (CR-1, TDGF1) is a cell surface/secreted oncoprotein actively involved in development and cancer. Here, we report that high expression of CRIPTO correlates with poor survival in stratified risk groups of prostate cancer (PCa) patients. CRIPTO and its signaling partner glucose-regulated protein 78 (GRP78) are highly expressed in PCa metastases and display higher levels in the metastatic ALDHhigh sub-population of PC-3M-Pro4Luc2 PCa cells compared with non-metastatic ALDHlow. Coculture of the osteotropic PC-3M-Pro4Luc2 PCa cells with differentiated primary human osteoblasts induced CRIPTO and GRP78 expression in cancer cells and increases the size of the ALDHhigh sub-population. Additionally, CRIPTO or GRP78 knockdown decreases proliferation, migration, clonogenicity and the size of the metastasis-initiating ALDHhigh sub-population. CRIPTO knockdown reduces the invasion of PC-3M-Pro4Luc2 cells in zebrafish and inhibits bone metastasis in a preclinical mouse model. These results highlight a functional role for CRIPTO and GRP78 in PCa metastasis and suggest that targeting CRIPTO/GRP78 signaling may have significant therapeutic potential.
Subject(s)
Bone Neoplasms/secondary , GPI-Linked Proteins/metabolism , Heat-Shock Proteins/metabolism , Intercellular Signaling Peptides and Proteins/metabolism , Neoplasm Proteins/metabolism , Prostatic Neoplasms/pathology , Animals , Bone Neoplasms/metabolism , Cell Line, Tumor , Cell Movement , Cell Proliferation , Endoplasmic Reticulum Chaperone BiP , GPI-Linked Proteins/genetics , Gene Knockdown Techniques , Heat-Shock Proteins/genetics , Humans , Intercellular Signaling Peptides and Proteins/genetics , Kaplan-Meier Estimate , Male , Mice , Mice, Nude , Neoplasm Proteins/genetics , Neoplasm Transplantation , Prostatic Neoplasms/geneticsABSTRACT
Ewing sarcoma is characterized by the expression of the chimeric EWSR1-FLI1 transcription factor. Proteomic analyses indicate that the decrease of EWSR1-FLI1 expression leads to major changes in effectors of the dynamics of the actin cytoskeleton and the adhesion processes with a shift from cell-to-cell to cell-matrix adhesion. These changes are associated with a dramatic increase of in vivo cell migration and invasion potential. Importantly, EWSR1-FLI1 expression, evaluated by single-cell RT-ddPCR/immunofluorescence analyses, and activity, assessed by expression of EWSR1-FLI1 downstream targets, are heterogeneous in cell lines and in tumours and can fluctuate along time in a fully reversible process between EWSR1-FLI1high states, characterized by highly active cell proliferation, and EWSR1-FLI1low states where cells have a strong propensity to migrate, invade and metastasize. This new model of phenotypic plasticity proposes that the dynamic fluctuation of the expression level of a dominant oncogene is an intrinsic characteristic of its oncogenic potential.
