LRIG1 overexpression inhibits PTEN expression in esophageal squamous cell carcinoma cell lines. (A) Eca-109 (magnification, ×50) and (B) KYSE-450 cells (magnification, ×100) were transfected with pLRIG1-GFP or pEGFP-N1 (control) for 48 h, after which the cells were observed under a microscope. (C) The mRNA expression levels of LRIG1 and PTEN in Eca-109 and KYSE-450 cells were analyzed by reverse transcription-quantitative polymerase chain reaction. The mRNA expression levels of LRIG1 were increased 11,680-fold (Eca-109) and 3,351 (KYSE-450) compared with the negative control. (D) The protein expression levels of LRIG1 and PTEN in Eca-109 and KYSE-450 cells were determined by western blotting and densitometry. The protein expression levels of LRIG1 were increased by ~10.1% in KYSE-450 cells and 50.5% in Eca-109 cells compared with the negative control cells. The mRNA and protein expression levels of PTEN were decreased in pLRIG1-GFP-transfected cell lines. Data are presented as the mean ± standard deviation of three independent experiments. *P<0.05 vs. the control. LRIG1, leucine-rich repeats and immunoglobulin-like domain protein 1; PTEN, phosphatase and tensin homolog; GFP, green fluorescent protein.