Nuclear localization of Galectin-3 in transformed thyroid cells: a role in transcriptional regulation

https://doi.org/10.1016/S0006-291X(03)00151-7Get rights and content

Abstract

The differential proteomic approach (2D gel analysis coupled to MALDI-MS analysis) of nuclear proteins can provide an extremely useful tool to understand control of cell proliferation and differentiation. In order to identify possible markers of dedifferentiation between normal and cancerous thyroid cells, we used a differential proteomics approach by comparing nuclear extracts from the normal rat thyroid cell line FRTL-5 and the completely undifferentiated Ki-mol cell line, obtained by transformation with the Ki-ras oncogene. Galectin-3 (Gal-3) was identified as highly expressed, in the nuclear compartment, only in the transformed cell line. By using different human cancer cell lines, we showed that Gal-3 is maximally expressed in nuclei of papillary cancer cells. We focused on the functional relationship existing between Gal-3 and the thyroid-specific transcription factor TTF-1, whose expression is maintained in papillary cancer where it can contribute to the proliferating status. By using gel-retardation and transient tranfection assays, we demonstrate that Gal-3 upregulates the TTF-1 transcriptional activity. GST-pulldown experiments demonstrate the occurrence of interaction between Gal-3 and TTF-1 homeodomain. Since several lines of evidence suggest a role for Gal-3 in controlling proliferation and tumor progression in thyroid cancer, the stimulatory activity played by Gal-3 over TTF-1 would account for a possible molecular mechanism through which the galectin controls proliferation in thyroid cells.

Section snippets

Experimental procedures

Oligodeoxynucleotide synthesis and DNA constructs. Oligodeoxynucleotides were purchased from MWG-Biotech, Ebersberg, Germany.

Plasmid encoding for recombinant TTF-1 homeodomain was described elsewhere [6]. Plasmid pTACAT3 contains the wild-type Tg promoter linked to the CAT gene and was already described [7]. Plasmid expressing protein TTF-1 was described elsewhere [8]. Plasmid encoding for Gal-3 was kindly provided by Dr. C. Hughes (National Institute for Medical Research, Mill Hill, London).

2D-PAGE analysis of nuclear extracts from Ki-mol and FRTL-5 cell lines

In order to investigate the presence of nuclear proteins differently expressed between the highly differentiated FRTL-5 rat thyroid cell line and the completely undifferentiated Ki-mol cell line, nuclear extracts were prepared as previously described [10]. The quality of the nuclear extracts was tested for the presence of the nuclear-specific transcription factor Pax-8 by Western blot analysis (data not shown). Then, expression profiles of nuclear proteins from FRTL-5 and Ki-mol cell lines were

Discussion

Thyroid cancers consist of diverse groups of neoplasms exhibiting different degrees of differentiation and aggressiveness [28]. In order to identify possible markers of dedifferentiation in thyroid cells, we used a differential proteomics approach comparing nuclear extracts from normal rat thyroid cell line FRTL-5 and transformed Ki-mol cell line.

Gal-3 was identified as expressed in the transformed cell line but not in the normal counterpart [19], [20], [21]. However, our results for the first

Acknowledgements

This work was supported by grants from the Italian National Research Council, Target Project on Biotechnology and from the Ministero per l’Università e la Ricerca Scientifica e Tecnologica (MIUR) to G.D. and from the University of Trieste to G.T.

References (43)

  • L. Wang et al.

    Galectin-3 is a nuclear matrix protein which binds RNA

    Biochem. Biophys. Res. Commun.

    (1995)
  • C. Liu et al.

    GATA-6 and thyroid transcription factor-1 directly interact and regulate surfactant protein-C gene expression

    J. Biol. Chem.

    (2002)
  • T. Yoshii et al.

    Galectin-3 phosphorylation is required for its anti-apoptotic function and cell cycle arrest

    J. Biol. Chem.

    (2002)
  • H. Inohara et al.

    Galectin-3 stimulates cell proliferation

    Exp. Cell. Res.

    (1998)
  • B.K. Moon et al.

    Galectin-3 protects human breast carcinoma cells against nitric oxide-induced apoptosis: implication of galectin-3 function during metastasis

    Am. J. Pathol.

    (2001)
  • X. Sanjuan et al.

    Differential expression of galectin 3 and galectin 1 in colorectal cancer progression

    Gastroenterology

    (1997)
  • O. Huber et al.

    Nuclear localization of β-catenin by interaction with transcription factor LEF-1

    Mech. Dev.

    (1996)
  • G. Damante et al.

    A unique combination of transcription factors controls differentiation of thyroid cells

    Prog. Nucleic Acids Res.

    (2001)
  • F.S. Ambesi-Impiombato et al.

    Culture of hormone-dependent functional epithelial cells from rat thyroids

    Proc. Natl. Acad. Sci. USA

    (1980)
  • A. Fusco et al.

    One- and two-step transformations of rat thyroid epithelial cells by retroviral oncogenes

    Mol. Cell. Biol.

    (1987)
  • G. Damante et al.

    Several regions of Antennapedia and thyroid transcription factor 1 homeodomains contribute to DNA binding specificity

    Proc. Natl. Acad. Sci. USA

    (1991)
  • Cited by (99)

    • Leukemia cells apoptosis by a newly discovered heterogeneous polysaccharide from Angelica sinensis (Oliv.) Diels

      2020, Carbohydrate Polymers
      Citation Excerpt :

      Gal-3 on cell surfaces and in the extracellular matrix is bound to its extracellular counterparts such as glycoproteins and glycolipids, to deliver signals inside the cell, regulate mitosis, apoptosis and cell-cycle progression in tumor cells (Liu & Rabinovich, 2005; van den Brule, Califice, & Castronovo, 2002). Furthermore, it has been reported that the nuclear Gal-3 increases with malignant transformation of thyroid cells (Paron et al., 2003). Different expression of Gal-3 in tumor cells is associated with the occurance, progression and metastasis of the tumor (Cheng et al., 2013).

    • Galectin-3 is expressed in the myocardium very early post-myocardial infarction

      2015, Cardiovascular Pathology
      Citation Excerpt :

      It is found on the cell surface and within the extracellular matrix, as well as in the cytoplasm and the nucleus of cells. Its localization depends on factors such as cell type and proliferation state [6–10], cultivation conditions [11], and neoplastic progression [12–16] and transformation [17,18]. The distribution in many types of cells, together with varied subcellular localization, indicates that GAL-3 has many different roles in normal and pathophysiological conditions [19,20].

    View all citing articles on Scopus
    View full text