Galectin 1 promotes tumor cell migration by enhancing Na+/H+ exchanger isoform 1 (NHE1) activity

BOCANEGRA VICTORIA; CROCI DIEGO; COSTANTINO VALERIA; GIL LORENZO ANDREA; GARRAMUÑO VALLÉS, PATRICIA; RAVINOVICH GABRIEL ADRIÁN; CACCIAMANI VALERIA

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

Tumor cells evade the immune response and modulate the microenvironment establishing a distinctive cell phenotype. Among these events Galectin 1 (Gal1), a glycan-binding protein, appear as a potent modulator of the tumor microenvironment through its binding to specific cell surface glycan structures. In solid tumors, the Na+/H+ exchanger isoform 1 (NHE1) favors cancer progression trough pH modulation. We aimed to elucidate the role of Gal1 on NHE1 regulation in murine melanoma cells and its possible role in tumor cell migration. To determine NHE1 activity we use a BCECF-AM flow cytometry kinetic assay. We observed increased NHE1 activity in tumor melanoma cells in comparison to a non-tumor cell line. To address if Gal1 could be involved in NHE1 hyperactivity, cells were treated with NHE1 inhibitor (Eipa), recombinant Gal1 (rGal1) or were silenced for Gal1 (shGal1). We observed diminished NHE1 activity after Eipa treatment with similar results after shGal1 silencing. Notably, rGal1 treatment induced increased NHE1 activity, even in the presence of Eipa reverting the Eipa-dependent inhibition of this Na+/H+ exchanger. Moreover, NHE1 upregulation was observe in response to exogenous administration of rhGal1 and silencing of Gal1 expression in melanoma cells decreased NHE1 expression. In this sense, we observed a specific coimmunoprecipitation of Gal1 with NHE1 suggesting that Gal1 could interacts and regulates the pH-dependent regulation of NHE1. To further address the biological significance of NHE1/Gal1 interaction, we evaluate migration of shGal1 melanoma cells. Both Gal1 signaling or NHE-1 inhibition impairs B16 cell migration. In, contrast to exogenous administration of rhGal1 restores migration in both conditions (p