CELLS DERIVED FROM CLEAR RENAL CELL CARCINOMA HAVE A DIFFERENT NHE1 CELL LOCALIZATION THAN CELLS DERIVED FROM HEALTHY RENAL PROXIMAL EPITHELIA

MECHALI A; VAN BALEN V; AMABILE MN; BELTRAMONE N; CAPURRO C; DI GIUSTO G; FORD P; RIVAROLA V

Mar del Plata

Congreso; Reunion Conjunta SAIC SAI SAFIS; 2022

Sociedad Argentina de Fisiologia

Even though pH homeostasis is critical for cell survival, extracellular acidosis is a hallmark of cancers. It has been described that the NHE1 isoform of the Na+/H+ exchanger would be associated with the adaptation of cancer cells to an acid extracellular environment. However, our previous studies in healthy and clear cell cancer-derived proximal cells, showed that total NHE1 expression was higher in healthy renal proximal epithelial than in cancer cells. This study aimed to investigate whether NHE1 cell localization or its function was different in cancer cells as compared to healthy ones. We use three renal cell models: HK2, derived from normal human proximal epithelial cells; 786-O and Caki-1 cells, derived from human renal clear cell carcinoma. We analyzed NHE1 cell localization with immunofluorescence followed by confocal microscopy using two NHE1 antibodies: one directed to an extracellular epitope (NHE1 plasmatic membrane expression) and the other to an intracellular one (total NHE1 expression). We also analyzed the NHE1 activity with ammonium pulse pHi experiments using BCECF cell fluorescence. Results showed that even though HK2 cells have high total NHE1 expression, most of it was localized inside the cell. On the contrary, both 786-O and Caki-1 cells have high NHE1 both, inside the cells and in their plasma membrane. Moreover, NHE1 function correlated with plasma membrane expression as NHE1-associated ammonium pulse recovery was higher in cancer-derived cells than in HK2 cells (NHE1 recovery, 10-5 pH units. s-1, HK2: 63 ± 7; 786-O: 175 ± 11; Caki-1: 99 ± 9. HK2 vs 786-O p