E-7820

Integrins are transmembrane proteins that mediate cell adhesion to extracellular matrix. Whereas expression of integrin alpha 2 is associated with motility, invasiveness and cellular differentiation in various tumors, the role of integrin alpha 2 in lung cancer has not been studied in detail. The aim of this study was to determine whether and how aberrant integrin alpha 2 expression in non-small cell lung cancer leads to different outcomes.

We measured expression of integrin alpha 2 by quantitative polymerase chain reaction in 100 samples collected from non-small cell lung cancer patients who had undergone surgical resection. We assigned patients to high and low expression groups and analyzed survival. Cellular morphology, adhesion, proliferation, migration and invasion were examined in human lung cancer cell lines.

Among 100 cases, 41 were female, with a median age of 71 years. High expression of integrin alpha 2 in non-small cell lung cancer was associated with lower recurrence-free survival (P = 0.004). Overexpression of integrin alpha 2 in cell lines had no effect on cell proliferation or invasion but resulted in increased cell size (1416 μm2 versus 470 μm2 in H522 cells, P < 0.001; 1822 μm2 versus 1029 μm2 in H661 cells, P = 0.02), adhesion (P < 0.001 in H522 and H661 cells) and migration (gap area filled was 71% versus 36% in H522 cells, P < 0.001; 57% versus 26% in H661 cells, P = 0.001). These changes were suppressed by E7820, an inhibitor of integrin alpha 2.

Integrin alpha 2 may play a significant role in lung cancer adhesion and migration, and may lead to a higher risk of recurrence.

Methotrexate (MTX) is widely used to treat various diseases. However, it induces adverse reactions like serious lung injury, including pulmonary fibrosis. Increasing evidence suggests that epithelial-mesenchymal transition (EMT) in injured alveolar epithelium contributes to the development of the pathophysiological state of the lung. We demonstrated that MTX induced EMT in cultured alveolar epithelial cell lines. Integrin-mediated signaling is considered a significant factor in recognizing the EMT process. However, the relationship between MTX-induced EMT and integrin family members is poorly understood. In the present study, we aimed to clarify the role of integrin in MTX-induced EMT in A549 and NCI-H1299 (H1299) cells by focusing on the integrin alpha 2 (ITGA2) subunit, selected based on our microarray analysis. MTX treatment for 72 h significantly increased the mRNA and cell surface expression of ITGA2 in both cell lines. However, this upregulation by MTX was suppressed by co-treatment with SB431542 and folic acid, which are inhibitors of MTX-induced EMT in A549 cells. The mRNA expression levels of EMT-related genes were more affected in the MTX-treated A549 cells with high ITGA2 expression than in those with low ITGA2 expression. Finally, E7820, an ITGA2 inhibitor, suppressed MTX-induced EMT-related phenotypic changes, such as morphology and mRNA and protein expression of α-smooth muscle actin, a representative EMT marker. These findings suggest that ITGA2 may play a key role in MTX-induced EMT in alveolar epithelial cells.