The Impact of Calcineurin B Homologous Protein Isoform 2 Expression on Non‐small Cell Lung Cancer Cell Function under Hypoxic Conditions

Abstract

The Na+‐H+ exchanger isoform 1 (NHE1) is a transmembrane protein that regulates a range of cellular functions essential for cancer progression including cell adhesion, proliferation and migration. The calcineurin B homologous proteins (CHP1 and CHP2) appear to be essential cofactors to support NHE1 function. CHP2 is expressed primarily in tumor cells where it binds to NHE1 with a 5‐10 fold higher affinity than CHP1. In these studies we investigate the role of hypoxia in the regulation of CHP2 expression and the role of this expression in the regulation of cell proliferation, migration, and invasion. To evaluate the role of CHP2 and NHE1 in NSCLC progression we use three cell lines. H1299 cells are a human NSCLC carcinoma cell line. H1299 CHP2KD is a modified H1299 cell line that lacks CHP2 expression and H1299 NHE1KD which lacks NHE1 expression. We have assessed the expression of CHP1, CHP2 and NHE1 in normal (10%) and low (0.5%) serum conditions under both normoxic (21%) and hypoxic (1%) conditions through western blot analysis. While CHP1 and NHE1 expression does not change under these conditions, CHP2 expression is increased in both low serum and hypoxic conditions. We will present data evaluating the role of CHP2 expression in cellular functions including proliferation, migration, and invasion measured using Electric Cell‐substrate Impedance Sensing (ECIS). ECIS is a real‐time, label‐free method to measure changes in cell properties.