DOK7V1 influences the malignant phenotype of lung cancer cells through PI3K/AKT/mTOR and FAK/paxillin signaling pathways

Abstract

Downstream of tyrosine kinase 7 transcript variant 1 (DOK7V1) is a docking protein mediating signal transduction between receptors and intracellular downstream molecules. Our previous study indicated that DOK7V1 was decreased in lung cancer and its lower expression was associated with a decreased survival rate. The 5‑year overall survival rate for patients with lung cancer was 20.2 and 18.6% for high and low DOK7 expression, respectively; the 5‑year disease‑free survival rate for patients with lung cancer was 14.3 and 16.9% for high and low DOK7 expression, respectively. DOK7V1 inhibited proliferation and migration, but enhanced adhesion, of lung cancer cells. In the present study, the effect of DOK7V1 and its domains [pleckstrin homology (PH) and phosphotyrosine‑binding (PTB) domain] on the malignant phenotype and associated signaling pathway in lung cancer cells was investigated. The results indicated that truncation of DOK7V1 domains (DOK7V1Δ‑PH and DOK7V1Δ‑PTB) inhibited the proliferation and migration of lung cancer cells which exhibited the same trend as DOK7V1, whereas DOK7V1Δ‑PH and DOK7V1Δ‑PTB exhibited different functions from those of DOK7V1 in cell matrix adhesion. Consistently, DOK7V1 overexpression in lung cancer cells suppressed the phosphoinositide 3‑kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathways, but activated the focal adhesion kinase (FAK)/paxillin signaling pathway. Taken together, these results indicate that DOK7V1 may inhibit proliferation and migration via negatively regulating the PI3K/AKT/mTOR signaling pathway, and increase adhesion by upregulating the FAK/paxillin signaling pathway in lung cancer cells.

Keywords: downstream of tyrosine kinase 7; phosphotyrosinebinding domain; pleckstrin homology domain; proliferation; AKT; FAK.