Publication Date:
2012-05-16
Description:
Sialyl Lewis x (sLex) and sialyl Lewis a (sLea) glycans are expressed on highly metastatic colon cancer cells. They promote extravasation of cancer cells and tumor angiogenesis via interacting with E-selectin on endothelial cells. Recently, epithelial–mesenchymal transition (EMT) has been noted as a critical phenotypic alteration in metastatic cancer cells. To address the association between sLex/a expression and EMT, we assessed whether sLex/a are highly expressed on colon cancer cells undergoing EMT. Treatment of HT29 and DLD-1 cells with EGF and/or basic FGF (bFGF) induced EMT and significantly increased sLex/a expression resulting in enhanced E-selectin binding activity. The transcript levels of the glycosyltransferase genes ST3GAL1/3/4 and FUT3 were significantly elevated and that of FUT2 was significantly suppressed by the treatment. We provide evidence that ST3GAL1/3/4 and FUT3 are transcriptionally up-regulated by c-Myc with probable involvement of Ser62 phosphorylation, and that FUT2 is transcriptionally down-regulated through the attenuation of CDX2. The contribution of c-Myc and CDX2 to the sLex/a induction was proved to be significant by knockdown or forced expression experiments. Interestingly, the cells undergoing EMT exhibited significantly increased VEGF secretion, which can promote tumor angiogenesis in cooperation with sLex/a. Finally, immunohistological study indicated high E-selectin ligand expression on cancer cells undergoing EMT in vivo, supporting their coexistence observed in vitro. These results suggest a significant link between sLex/a expression and EMT in colon cancer cells and a pivotal role of c-Myc and CDX2 in regulating sLex/a expression during EMT.
Print ISSN:
0027-8424
Electronic ISSN:
1091-6490
Topics:
Biology
,
Medicine
,
Natural Sciences in General
Permalink
