Epidermal growth factor receptor activity upregulates lactate dehydrogenase A expression, lactate dehydrogenase activity, and lactate secretion in cultured IB3-1 cystic fibrosis lung epithelial cells

MASSIP-COPIZ, MARÍA MACARENA; MORI, CONSUELO; SANTA-COLOMA, TOMÁS A.; CLAUZURE, MARIÁNGELES; AGUILAR, MARÍA Á.; VALDIVIESO, ÁNGEL G.; ASENSIO, CRISTIAN J.A.

BIOCHEMISTRY AND CELL BIOLOGY

NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS

Lugar: OTAWA; Año: 2020 vol. 99 p. 476 - 487

0829-8211

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. It has been postulated that reduced HCO3- transport through CFTR may lead to a decreased airway surface liquid pH. In contrast, others have reported no changes in the extracellular pH (pHe). We have recently reported that in carcinoma Caco-2/pRS26 cells (transfected with short hairpin RNA for CFTR) or CF lung epithelial IB3-1 cells, the mutation in CFTR decreased mitochondrial complex I activity and increased lactic acid production, owing to an autocrine IL-1β loop. The secreted lactate accounted for the reduced pHe, because oxamate fully restored the pHe. These effects were attributed to the IL-1β autocrine loop and the downstream signaling kinases c-Src and JNK. Here we show that the pHe of IB3-1 cells can be restored to normal values (∼7.4) by incubation with the epidermal growth factor receptor (EGFR, HER1, ErbB1) inhibitors AG1478 and PD168393. PD168393 fully restored the pHe values of IB3-1 cells, suggesting that the reduced pHe is mainly due to increased EGFR activity and lactate. Also, in IB3-1 cells, lactate dehydrogenase A mRNA, protein expression, and activity are downregulated when EGFR is inhibited. Thus, a constitutive EGFR activation seems to be responsible for the reduced pHe in IB3-1 cells.