ABSTRACT
Lymphocytic choriomeningitis virus (LCMV) is a rodent-borne zoonotic arenavirus that causes congenital abnormalities and can be fatal for transplant recipients. Using a genome-wide loss-of-function screen, we identify host factors required for LCMV entry into cells. We identify the lysosomal mucin CD164, glycosylation factors, the heparan sulfate biosynthesis machinery, and the known receptor alpha-dystroglycan (α-DG). Biochemical analysis revealed that the LCMV glycoprotein binds CD164 at acidic pH and requires a sialylated glycan at residue N104. We demonstrate that LCMV entry proceeds by the virus switching binding from heparan sulfate or α-DG at the plasma membrane to CD164 prior to membrane fusion, thus identifying additional potential targets for therapeutic intervention.
Subject(s)
Lymphocytic choriomeningitis virus/physiology , Virus Internalization , A549 Cells , CRISPR-Cas Systems , Endolyn/physiology , Gene Editing , HEK293 Cells , HeLa Cells , Host-Pathogen Interactions , Humans , Hydrogen-Ion Concentration , Lymphocytic choriomeningitis virus/pathogenicity , Membrane Fusion , Virulence FactorsABSTRACT
BACKGROUND: CD164 (endolyn), a sialomucin, has been reported to play a role in the proliferation, adhesion, and differentiation of hematopoietic stem cells. The potential association of CD164 with tumorigenicity remains unclear. METHODS: The clinicopathological correlation of ovarian cancer with CD164 was assessed in a 97-patient tumor tissue microarray. Overexpression or silence CD164 was to analyze the effect of CD164 on the proliferation, colony formation and apoptosis via a mouse xenograft and western blotting analysis. The subcellular localization of CD164 was collected in the immunohistochemical and confocal analysis. RESULTS: Our data demonstrated that higher expression levels of CD164 were identified in malignant ovarian cancer cell lines, such as SKOV3 and HeyA8. The clinicopathological correlation analysis showed that the upregulation of CD164 protein was significantly associated with tumor grade and metastasis. The overexpression of CD164 in human ovarian epithelial surface cells promoted cellular proliferation and colony formation and suppressed apoptosis. These tumorigenicity effects of CD164 were reconfirmed in a mouse xenograft model. We also found that the overexpression of CD164 proteins increased the amounts of CXCR4 and SDF-1α and activated the SDF-1α/CXCR4 axis, inducing colony and sphere formation. Finally, we identified the subcellular localization of CD164 in the nucleus and cytosol and found that nuclear CD164 might be involved in the regulation of the activity of the CXCR4 promoter. CONCLUSIONS: Our findings suggest that the increased expression of CD164 is involved in ovarian cancer progression via the SDF-1α/CXCR4 axis, which promotes tumorigenicity. Thus, targeting CD164 may serve as a potential ovarian cancer biomarker, and targeting CD164 may serve as a therapeutic modality in the management of high-grade ovarian tumors.
Subject(s)
Chemokine CXCL12/metabolism , Neoplasms, Glandular and Epithelial/metabolism , Ovarian Neoplasms/metabolism , Receptors, CXCR4/metabolism , Animals , Biomarkers, Tumor/metabolism , Cell Line, Tumor , Cell Transformation, Neoplastic/metabolism , Endolyn/physiology , Epithelial Cells/metabolism , Epithelial Cells/pathology , Female , Gene Expression Regulation, Neoplastic , Humans , Mice , Mice, Nude , Middle Aged , Neoplasm Transplantation , Neoplasms, Glandular and Epithelial/pathology , Neoplastic Stem Cells/metabolism , Ovarian Neoplasms/pathology , Phosphatidylinositol 3-Kinases/metabolism , Prognosis , Promoter Regions, Genetic , Proto-Oncogene Proteins c-akt/metabolism , Receptors, CXCR4/genetics , Tissue Array Analysis , Transcription Factors/genetics , Transcription Factors/metabolism , Transcriptional Activation , Tumor BurdenABSTRACT
BACKGROUND: CD164 (Endolyn) is a sialomucin, which has been found to play roles in regulating proliferation, adhesion, and differentiation of hematopoietic stem cells. Possible association of CD164 with solid cancer development remains unknown. METHODS AND RESULTS: We first studied CD164 expression in biopsies from colorectal cancer, breast, and ovary cancer patients by semi-quantitative immunohistochemistry, and found that CD164 was strongly expressed in all the colorectal cancer samples compared to the matching normal colon tissues. The possible roles of CD164 in colon cancer development were further investigated using a well-established human colon cancer cell line HCT116. We found that knockdown of CD164 expression in HCT116 cells significantly inhibited cell proliferation, mobility, and metastasis in vitro and in vivo. The knockdown of CD164 expression was associated with decreased chemokine receptor CXCR4 expression HCT116 cell surface and immunoprecipitation studies showed that CD164 formed complexes with CXCR4. CONCLUSIONS: CD164 is highly expressed in the colon cancer sites, and it promotes HCT116 colon cancer cell proliferation and metastasis both in vitro and in vivo, and the effects may act through regulating CXCR4 signaling pathway. Therefore, CD164 may be a new target for diagnosis and treatment for colon cancer.
