Paradoxical induction of growth arrest and apoptosis by EGF via the up-regulation of PTEN by activating Redox factor-1/Egr-1 in human lung cancer cells

// Je-won Ryu 1, * , Sung Sik Choe 2, * , Seung-Hee Ryu 1 , Eun-Young Park 1 , Byoung Wook Lee 3 , Tae Keun Kim 4 , Chang Hoon Ha 3 , Sang-wook Lee 1 1 Department of Radiation Oncology, Asan Medical Center and University of Ulsan College of Medicine, Seoul, Republic of Korea 2 Department of Biological Sciences, Institute of Molecular Biology and Genetics, National Creative Research Institutive Center for Adipose Tissue Remodeling, Seoul National University, Seoul, Republic of Korea 3 Asan Institute for Life Science, Asan Medical Center and University of Ulsan College of Medicine, Seoul, Republic of Korea 4 Department of Life Science, College of Natural Science, Hallym University, Kyeongki Province, Republic of Korea * These authors contributed equally to this work Correspondence to: Chang Hoon Ha, email: chhoonha@gmail.com Sang-Wook Lee, email: lsw@amc.seoul.kr Keywords: Epidermal Growth Factor (EGF), Purinergic Receptor 2(P2Y), Redox Factor-1(Ref-1), Zinc Finger-containing Transcriptional Regulator 1(EGR1), Phosphatase and Tensin Homolog (PTEN) Received: September 30, 2016 Accepted: November 24, 2016 Published: December 07, 2016 ABSTRACT Epidermal growth factor (EGF) signaling promotes cell proliferation and survival in several types of cancer. Here, however, we showed that EGF inhibits proliferation and promotes programmed cell death in non-small cell lung cancer (NSCLC) cells. In A549 cells, EGF increased redox factor-1 (Ref-1) expression and the association of Ref-1 with zinc finger-containing transcriptional regulator (EGR1) via activation of p22 phox , RAC1, and an NADPH oxidase subunit. EGF increased p22 phox and RAC1 expression through activation of purinergic receptors (P2Y). Elevated Ref-1/EGR1 levels increased phosphatase and tensin homolog (PTEN) levels, leading to inhibition of the Akt pathway. EGF-induced PTEN upregulation increased apoptosis and autophagy-induced damage in A549 cells, whereas Ref-1 knockdown blocked EGF-induced PTEN upregulation in an NADPH oxidase p22 phox subunit-independent manner. In addition, p22 phox knockdown restored EGF-induced effects, implying that changes in P2Y activity caused by EGF, which activates NADPH oxidase via RAC1, influenced Ref-1-mediated redox regulation. Finally, EGF similarly attenuated cell proliferation and promoted autophagy and apoptosis in vivo in a xenograft model using A549 cells. These findings reveal that EGF-induced redox signaling is linked to Ref-1-induced death in NSCLC cells.