ABSTRACT
Previous studies have suggested that overexpression of the oncogenic protein epithelial membrane protein-2 (EMP2) correlates with endometrial carcinoma progression and ultimately poor survival from disease. To understand the role of EMP2 in the etiology of disease, gene analysis was performed to show transcripts that are reciprocally regulated by EMP2 levels. In particular, EMP2 expression correlates with and helps regulate the expression of several cancer stem cell associated markers including aldehyde dehydrogenase 1 (ALDH1). ALDH expression significantly promotes tumor initiation and correlates with the levels of EMP2 expression in both patient samples and tumor cell lines. As therapy against cancer stem cells in endometrial cancer is lacking, the ability of anti-EMP2 IgG1 therapy to reduce primary and secondary tumor formation using xenograft HEC1A models was determined. Anti-EMP2 IgG1 reduced the expression and activity of ALDH and correspondingly reduced both primary and secondary tumor load. Our results collectively suggest that anti-EMP2 therapy may be a novel method of reducing endometrial cancer stem cells.
Subject(s)
Endometrial Neoplasms/metabolism , Gene Expression Regulation, Neoplastic/drug effects , Immunoglobulin G/pharmacology , Isoenzymes/metabolism , Membrane Glycoproteins/antagonists & inhibitors , Neoplastic Stem Cells/metabolism , Retinal Dehydrogenase/metabolism , Aldehyde Dehydrogenase 1 Family , Animals , Biomarkers, Tumor/genetics , Biomarkers, Tumor/metabolism , Carcinogenesis/drug effects , Carcinogenesis/metabolism , Carcinogenesis/pathology , Cell Line, Tumor , Endometrial Neoplasms/drug therapy , Endometrial Neoplasms/pathology , Female , Gene Expression Profiling , Humans , Isoenzymes/genetics , Membrane Glycoproteins/genetics , Membrane Glycoproteins/metabolism , Mice , Mice, Inbred BALB C , Mice, Nude , Mice, SCID , Neoplastic Stem Cells/drug effects , Neoplastic Stem Cells/pathology , Retinal Dehydrogenase/genetics , Xenograft Model Antitumor AssaysABSTRACT
Understanding tumor-induced angiogenesis is a challenging problem with important consequences for the diagnosis and treatment of cancer. In this study, we define a novel function for epithelial membrane protein-2 (EMP2) in the control of angiogenesis. EMP2 functions as an oncogene in endometrial cancer, and its expression has been linked to decreased survival. Using endometrial cancer xenografts, modulation of EMP2 expression resulted in profound changes to the tumor microvasculature. Under hypoxic conditions, upregulation of EMP2 promoted vascular endothelial growth factors (VEGF) expression through a HIF-1α-dependent pathway and resulted in successful capillary-like tube formation. In contrast, reduction of EMP2 correlated with reduced HIF-1α and VEGF expression with the net consequence of poorly vascularized tumors in vivo. We have previously shown that targeting of EMP2 using diabodies in endometrial cancer resulted in a reduction of tumor load, and since then we have constructed a fully human EMP2 IgG1. Treatment of endometrial cancer cells with EMP2-IgG1 reduced tumor load with a significant improvement in survival. These results support the role of EMP2 in the control of the tumor microenvironment and confirm the cytotoxic effects observed by EMP2 treatment in vivo.
Subject(s)
Endometrial Neoplasms/blood supply , Membrane Glycoproteins/physiology , Neovascularization, Pathologic , Vascular Endothelial Growth Factor A/biosynthesis , Cell Line, Tumor , Endometrial Neoplasms/metabolism , Female , Humans , Immunoglobulin G/immunology , Membrane Glycoproteins/immunology , Survival AnalysisABSTRACT
A murine homologue of the epithelial membrane protein 2 (EMP2) gene was identified in a search for genes associated with B-cell lymphoma tumorigenicity by using suppression subtractive hybridization. Expression of EMP2 messenger RNA in primary mouse tissues was limited to certain epithelial cell types and the peritoneal lymphoid compartment. EMP2 was expressed in the poorly tumorigenic DAC B-lymphoma cell line but was significantly down-regulated in a subline selected for in vivo tumor formation in Balb/c mice. Recombinant restoration of EMP2 expression in the subline suppressed its tumorigenicity, suggesting that loss of EMP2 was a causal factor in the malignant phenotype. Recombinant overexpression of EMP2 was studied in B lymphoma and NIH3T3 cells. EMP2 in both cell types induced cell death on serum deprivation. EMP2-induced cell death correlated with the expression level of EMP2 protein and was prevented by caspase inhibitors Z-VAD and Z-DEVD. These findings for the first time describe an apoptotic effect of a GAS3 family gene in lymphocytes. They also suggest that EMP2 may influence B-lymphoma tumorigenicity through a functional tumor suppressor phenotype. (Blood. 2001;97:3890-3895)
Subject(s)
Lymphoma, B-Cell/genetics , Lymphoma, B-Cell/therapy , Membrane Glycoproteins/genetics , Membrane Glycoproteins/pharmacology , 3T3 Cells/drug effects , Animals , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , DNA, Complementary/isolation & purification , Epithelial Cells/chemistry , Gene Transfer Techniques , Genes, Tumor Suppressor , Genetic Therapy , Mice , Mice, Inbred BALB C , Neoplasm Transplantation , Tumor Cells, Cultured/cytology , Tumor Cells, Cultured/drug effectsABSTRACT
Fizzy-related (fzr) is a recently identified 7WD domain family member implicated in cell cycle regulation of Drosophila and yeast. In this study, the murine homologue of fzr was isolated by suppression subtractive hybridization as a gene with decreased expression during malignant progression of a murine B-lymphoma cell line. Retroviral overexpression of fzr in B-lymphoma cells reduced tumor formation. Those tumors that did arise had diminished or extinguished retroviral Fzr. Surprisingly, fzr overexpression dramatically increased B-lymphoma cell susceptibility to natural killer cell (NK) cytotoxicity, a host-resistant mechanism for tumor formation in this model system. These findings implicate fzr as a new category of genes suppressing B-cell tumorigenesis and suggest a novel role for fzr in the target cell interaction with NK cells.
