Hypoxia inducible factor-1 mediates expression of galectin-1: the potential role in migration/invasion of colorectal cancer cells

Abstract

The expression of galectin-1, one of the most important lectins participating in the malignant tumor development, has been shown to be regulated by hypoxia, but its exact mechanism remains elusive. Here, we find that ectopically expressed hypoxia-inducible factor (HIF) 1alpha protein, an oxygen-sensitive subunit of HIF-1 that is a master factor for cellular response to hypoxia, significantly increases galectin-1 expression in both messenger RNA and protein levels in all four colorectal cancer (CRC) cell lines tested. However, hypoxia-induced galectin-1 expression cannot be seen in sentrin/SUMO-specific protease 1 homozygous-null mouse embryonic fibroblasts that fail to accumulate HIF-1alpha protein. Furthermore, silence of HIF-1alpha or HIF-1beta expression by specific short hairpin RNAs (shRNAs) antagonizes hypoxia-induced galectin-1 expression. All these results propose that galectin-1 is a direct target of transcriptional factor HIF-1. Applying luciferase reporter assay and chromatin immunoprecipitation, we identify that two hypoxia-responsive elements located at -441 to -423 bp upstream to transcriptional start site of galectin-1 gene are essential for HIF-1-mediated galectin-1 expression. Finally, the knockdown of galectin-1 by its specific shRNA can significantly reduce hypoxia-induced invasion and migration of CRC cell line, and the ectopic expression of galectin-1 can remarkably restore invasion and migration abilities of HIF-1alpha-knocked SW620 cells, proposing that galectin-1 mediates the HIF-1-induced migration and invasion of CRC cells during hypoxia. Taken together, our results shed new light for understanding mechanism for hypoxia/HIF-1-mediated migration/invasion of CRC cells.

Synergistic Induction of Galectin-1 by CCAAT/Enhancer Binding Protein α and Hypoxia-inducible Factor 1α and Its Role in Differentiation of Acute Myeloid Leukemic Cells

“…S2B). These results suggest that HIF-1␣ directly targets the promoter of galectin-1, like that found in colorectal cancer cell lines (13). Considering that C/EBP␣ can interact with HIF-1␣ protein (27) and that galectin-1 is also a direct target of C/EBP␣, we addressed the potential relationship between C/EBP␣ and HIF-1␣ on the expression of galectin-1.…”

“…Chromatin Immunoprecipitation (ChIP) and ChIP Followed by ChIP (ChIP-reChIP) Assay-A ChIP assay was performed according to our previous report (13). Briefly, U937 cells were grown under normoxia or hypoxia for 24 h and then crosslinked with 1% formaldehyde at room temperature for 10 min.…”

“…Design and Transfection of shRNA-The target shRNA sequences for galectin-1, HIF-1␣, and C/EBP␣ were synthesized, annealed, and ligated into pSilencer 3.1-H1-neo according to the manufacturer's instructions (Ambion, Austin, TX) as described previously (13,17,18). Then, these targets and negative control shRNA-containing plasmids were transfected into U937T cells using the Bio-Rad Gene-Pulser II for electroporation.…”

“…It consists of an oxygen-sensitive ␣ subunit (HIF-1␣) and constitutively expressed ␤ subunit (HIF-1␤, also designated as aryl hydrocarbon receptor nuclear translocator) (12). We showed previously that galectin-1 is a direct target of the HIF-1 protein (13) and that HIF-1␣ can interact with and enhance the transcriptional activity of CCAAT/enhancer binding protein ␣ (C/EBP␣) (14), one of the master transcriptional factors involved in the differentiation of hematopoietic cells (15,16). Here we report that C/EBP␣ directly up-regulates the transcriptional expression of galectin-1 and presents a synergistic effect with HIF-1␣ for the induction of galectin-1 expression.…”

Presence of galectin-1 in the epidermal and dermal thickening of keloid tissues

“…Interestingly, abnormal vascularization has been associated not only with pronounced proliferation of endothelial cells [60] and hypoxia [11,61], but also with an elevated Gal-1 expression [62,63]. In fact, studies have shown that Gal-1 can induce endothelial cell proliferation [64,65] and that Gal-1 expression can be regulated by hypoxia [66,67]. Also of significance, some studies have provided evidence that local hypoxia not only promotes keratinocyte motility and migration during wound healing [68] but also stimulates the deposition of collagen by fibroblasts in wounds and keloids [69][70][71] and abnormal vascularization in keloids [11].…”