Identification of mRNA splicing factors as the endothelial receptor for carbohydrate-dependent lung colonization of cancer cells.
Cell surfaces of epithelial cancer are covered by complex carbohydrates, whose structures function in malignancy and metastasis. However, the mechanism underlying carbohydrate-dependent cancer metastasis has not been defined. Previously, we identified a carbohydrate-mimicry peptide designated I-peptide, which inhibits carbohydrate-dependent lung colonization of sialyl Lewis X-expressing B16-FTIII-M cells in E/P-selectin doubly-deficient mice. We hypothesized that lung endothelial cells express an unknown carbohydrate receptor, designated as I-peptide receptor (IPR), responsible for lung colonization of B16-FTIII-M cells. Here, we visualized IPR by in vivo biotinylation, which revealed that the major IPR is a group of 35-kDa proteins. IPR proteins isolated by I-peptide affinity chromatography were identified by proteomics as Ser/Arg-rich alternative pre-mRNA splicing factors or Sfrs1, Sfrs2, Sfrs5, and Sfrs7 gene products. Bacterially expressed Sfrs1 protein bound to B16-FTIII-M cells but not to parental B16 cells. Recombinant Sfrs1 protein bound to a series of fucosylated oligosaccharides in glycan array and plate-binding assays. When anti-Sfrs antibodies were injected intravenously into mice, antibodies labeled a subset of lung capillaries. Anti-Sfrs antibodies inhibited homing of I-peptide-displaying phage to the lung colonization of B16-FTIII-M cells in vivo in the mouse. These results strongly suggest that Sfrs proteins are responsible for fucosylated carbohydrate-dependent lung metastasis of epithelial cancers.
Hatakeyama
Shingo
S
Tumor Microenvironment Program, Cancer Research Center, Burnham Institute for Medical Research, La Jolla, CA 92037, USA.
Sugihara
Kazuhiro
K
Nakayama
Jun
J
Akama
Tomoya O
TO
Wong
Shuk-Man Annie
SM
Kawashima
Hiroto
H
Zhang
Jianing
J
Smith
David F
DF
Ohyama
Chikara
C
Fukuda
Minoru
M
Fukuda
Michiko N
MN
D000818:Animals; D000906:Antibodies / Q000276:immunology; D050260:Carbohydrate Metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism*; D008175:Lung Neoplasms / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009687:Nuclear Proteins / Q000378:metabolism*
D000906:Antibodies; D009687:Nuclear Proteins