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Hypoxia Up-Regulates Galectin-3 in Mammary Tumor Progression and Metastasis.

de Oliveira JT, Ribeiro C, Barros R, Gomes C, de Matos AJ, Reis CA, Rutteman GR, Gärtner F - PLoS ONE (2015)

Bottom Line: Increased galectin-3 expression was confirmed at the mRNA level.Under hypoxic conditions the expression of galectin-3 shifts from a predominant nuclear location to cytoplasmic and membrane expressions.In in vivo studies, galectin-3 was overexpressed in hypoxic areas of primary tumors and well-established metastases.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Institute of Molecular Pathology and Immunology (IPATIMUP), University of Porto, Porto, Portugal; Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), University of Porto, Porto, Portugal; Faculty of Veterinary Medicine of the Lusophone University of Humanities and Technologies, Lisbon, Portugal.

ABSTRACT
The tumor microenvironment encompasses several stressful conditions for cancer cells such as hypoxia, oxidative stress and pH alterations. Galectin-3, a well-studied member of the beta-galactoside-binding animal family of lectins has been implicated in multiple steps of metastasis as cell-cell and cell-ECM adhesion, promotion of angiogenesis, cell proliferation and resistance to apoptosis. However, both its aberrantly up- and down-regulated expression was observed in several types of cancer. Thus, the mechanisms that regulate galectin-3 expression in neoplastic settings are not clear. In order to demonstrate the putative role of hypoxia in regulating galectin-3 expression in canine mammary tumors (CMT), in vitro and in vivo studies were performed. In malignant CMT cells, hypoxia was observed to induce expression of galectin-3, a phenomenon that was almost completely prevented by catalase treatment of CMT-U27 cells. Increased galectin-3 expression was confirmed at the mRNA level. Under hypoxic conditions the expression of galectin-3 shifts from a predominant nuclear location to cytoplasmic and membrane expressions. In in vivo studies, galectin-3 was overexpressed in hypoxic areas of primary tumors and well-established metastases. Tumor hypoxia thus up-regulates the expression of galectin-3, which may in turn increase tumor aggressiveness.

No MeSH data available.


Related in: MedlinePlus

Galectin-3 mRNA expression under hypoxic conditions.(A) mRNA extracted from malignant CMT-U27 cell line was converted to cDNA and analyzed by real-time polymerase chain reaction (PCR) to assess quantitatively galectin-3 expression in CMT-U27 cells under hypoxic conditions. An increase in galectin-3 mRNA was observed only upon 24 hours of hypoxia treatment. No differences were seen in the transcription of HIF-1α, however the transcription of GAPDH and GLUT-1 seemed to early respond to hypoxia. cDNA contents were normalized on the basis of predetermined levels of 18S. (B) Representative mRNA expression of galectin-3, was visualized using a set of Stellaris RNA fluorescence in situ hybridization probes. GLUT-1 (green color) was used as a hypoxia control. Blue color shows the nucleus stained by DAPI. CMT-U27 cells exposed for 24 hours to hypoxia presented intense red FISH signals that are predominantly located in the cytoplasm and reflect the galectin-3 mRNA. Each spot corresponds to a single mRNA molecule.
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pone.0134458.g004: Galectin-3 mRNA expression under hypoxic conditions.(A) mRNA extracted from malignant CMT-U27 cell line was converted to cDNA and analyzed by real-time polymerase chain reaction (PCR) to assess quantitatively galectin-3 expression in CMT-U27 cells under hypoxic conditions. An increase in galectin-3 mRNA was observed only upon 24 hours of hypoxia treatment. No differences were seen in the transcription of HIF-1α, however the transcription of GAPDH and GLUT-1 seemed to early respond to hypoxia. cDNA contents were normalized on the basis of predetermined levels of 18S. (B) Representative mRNA expression of galectin-3, was visualized using a set of Stellaris RNA fluorescence in situ hybridization probes. GLUT-1 (green color) was used as a hypoxia control. Blue color shows the nucleus stained by DAPI. CMT-U27 cells exposed for 24 hours to hypoxia presented intense red FISH signals that are predominantly located in the cytoplasm and reflect the galectin-3 mRNA. Each spot corresponds to a single mRNA molecule.

Mentions: In order to determine whether the differing levels of galectin-3 expression levels reflected transcriptional regulation, we measured the lectin’s mRNA levels in CMT-U27 cells upon 6, 12, and 24 hours of hypoxia exposure. In fact, cells displayed higher expression levels of galectin-3 mRNA (4-fold increase) upon 24 hours of hypoxia exposure when compared with normoxic controls. We further investigated HIF-1α, GLUT-1 and GAPDH transcription in the hypoxic cells. After 6 hours of hypoxia, GLUT-1 and GAPDH mRNA levels were found to be 16- and 4-fold increased, respectively. When compared with normoxic cells, HIF-1α mRNA levels were not significantly altered at the studied time points (Fig 4A). To further assess galectin-3 mRNA expression by cells under hypoxic conditions (0.1% O2 for 24 hours), FISH analyses were performed, showing an increase of galectin-3 mRNA expression in a subset of the cells (Fig 4B). These results suggest that changes in of galectin-3 transcription may be a late response to hypoxia, when compared with GLUT-1 and GAPDH, in malignant CMT.


Hypoxia Up-Regulates Galectin-3 in Mammary Tumor Progression and Metastasis.

de Oliveira JT, Ribeiro C, Barros R, Gomes C, de Matos AJ, Reis CA, Rutteman GR, Gärtner F - PLoS ONE (2015)

Galectin-3 mRNA expression under hypoxic conditions.(A) mRNA extracted from malignant CMT-U27 cell line was converted to cDNA and analyzed by real-time polymerase chain reaction (PCR) to assess quantitatively galectin-3 expression in CMT-U27 cells under hypoxic conditions. An increase in galectin-3 mRNA was observed only upon 24 hours of hypoxia treatment. No differences were seen in the transcription of HIF-1α, however the transcription of GAPDH and GLUT-1 seemed to early respond to hypoxia. cDNA contents were normalized on the basis of predetermined levels of 18S. (B) Representative mRNA expression of galectin-3, was visualized using a set of Stellaris RNA fluorescence in situ hybridization probes. GLUT-1 (green color) was used as a hypoxia control. Blue color shows the nucleus stained by DAPI. CMT-U27 cells exposed for 24 hours to hypoxia presented intense red FISH signals that are predominantly located in the cytoplasm and reflect the galectin-3 mRNA. Each spot corresponds to a single mRNA molecule.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4519331&req=5

pone.0134458.g004: Galectin-3 mRNA expression under hypoxic conditions.(A) mRNA extracted from malignant CMT-U27 cell line was converted to cDNA and analyzed by real-time polymerase chain reaction (PCR) to assess quantitatively galectin-3 expression in CMT-U27 cells under hypoxic conditions. An increase in galectin-3 mRNA was observed only upon 24 hours of hypoxia treatment. No differences were seen in the transcription of HIF-1α, however the transcription of GAPDH and GLUT-1 seemed to early respond to hypoxia. cDNA contents were normalized on the basis of predetermined levels of 18S. (B) Representative mRNA expression of galectin-3, was visualized using a set of Stellaris RNA fluorescence in situ hybridization probes. GLUT-1 (green color) was used as a hypoxia control. Blue color shows the nucleus stained by DAPI. CMT-U27 cells exposed for 24 hours to hypoxia presented intense red FISH signals that are predominantly located in the cytoplasm and reflect the galectin-3 mRNA. Each spot corresponds to a single mRNA molecule.
Mentions: In order to determine whether the differing levels of galectin-3 expression levels reflected transcriptional regulation, we measured the lectin’s mRNA levels in CMT-U27 cells upon 6, 12, and 24 hours of hypoxia exposure. In fact, cells displayed higher expression levels of galectin-3 mRNA (4-fold increase) upon 24 hours of hypoxia exposure when compared with normoxic controls. We further investigated HIF-1α, GLUT-1 and GAPDH transcription in the hypoxic cells. After 6 hours of hypoxia, GLUT-1 and GAPDH mRNA levels were found to be 16- and 4-fold increased, respectively. When compared with normoxic cells, HIF-1α mRNA levels were not significantly altered at the studied time points (Fig 4A). To further assess galectin-3 mRNA expression by cells under hypoxic conditions (0.1% O2 for 24 hours), FISH analyses were performed, showing an increase of galectin-3 mRNA expression in a subset of the cells (Fig 4B). These results suggest that changes in of galectin-3 transcription may be a late response to hypoxia, when compared with GLUT-1 and GAPDH, in malignant CMT.

Bottom Line: Increased galectin-3 expression was confirmed at the mRNA level.Under hypoxic conditions the expression of galectin-3 shifts from a predominant nuclear location to cytoplasmic and membrane expressions.In in vivo studies, galectin-3 was overexpressed in hypoxic areas of primary tumors and well-established metastases.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Institute of Molecular Pathology and Immunology (IPATIMUP), University of Porto, Porto, Portugal; Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), University of Porto, Porto, Portugal; Faculty of Veterinary Medicine of the Lusophone University of Humanities and Technologies, Lisbon, Portugal.

ABSTRACT
The tumor microenvironment encompasses several stressful conditions for cancer cells such as hypoxia, oxidative stress and pH alterations. Galectin-3, a well-studied member of the beta-galactoside-binding animal family of lectins has been implicated in multiple steps of metastasis as cell-cell and cell-ECM adhesion, promotion of angiogenesis, cell proliferation and resistance to apoptosis. However, both its aberrantly up- and down-regulated expression was observed in several types of cancer. Thus, the mechanisms that regulate galectin-3 expression in neoplastic settings are not clear. In order to demonstrate the putative role of hypoxia in regulating galectin-3 expression in canine mammary tumors (CMT), in vitro and in vivo studies were performed. In malignant CMT cells, hypoxia was observed to induce expression of galectin-3, a phenomenon that was almost completely prevented by catalase treatment of CMT-U27 cells. Increased galectin-3 expression was confirmed at the mRNA level. Under hypoxic conditions the expression of galectin-3 shifts from a predominant nuclear location to cytoplasmic and membrane expressions. In in vivo studies, galectin-3 was overexpressed in hypoxic areas of primary tumors and well-established metastases. Tumor hypoxia thus up-regulates the expression of galectin-3, which may in turn increase tumor aggressiveness.

No MeSH data available.


Related in: MedlinePlus