Journal Article

Roles of PI3K/Akt and c-Jun Signaling Pathways in Human Papillomavirus Type 16 Oncoprotein-Induced HIF-1α, VEGF, and IL-8 Expression and In Vitro Angiogenesis in Non-Small Cell Lung Cancer Cells

Feng, Xiaowei, Liang, Jie, Zhang, Peihua, Liu, Fei, Zhang, Erying, Tang, Xudong

2014

Overview

Human papillomavirus (HPV)-16 infection may be related to non-smoking associated lung cancer. Our previous studies have found that HPV-16 oncoproteins promoted angiogenesis via enhancing hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), and interleukin-8 (IL-8) expression in non-small cell lung cancer (NSCLC) cells. In this study, we further investigated the roles of PI3K/Akt and c-Jun signaling pathways in it. Human NSCLC cell lines, A549 and NCI-H460, were stably transfected with pEGFP-16 E6 or E7 plasmids. Western blotting was performed to analyze the expression of HIF-1α, p-Akt, p-P70S6K, p-P85S6K, p-mTOR, p-JNK, and p-c-Jun proteins. VEGF and IL-8 protein secretion and mRNA levels were determined by ELISA and Real-time PCR, respectively. The in vitro angiogenesis was observed by human umbilical vein endothelial cells (HUVECs) tube formation assay. Co-immunoprecipitation was performed to analyze the interaction between c-Jun and HIF-1α. HPV-16 E6 and E7 oncoproteins promoted the activation of Akt, P70S6K, P85S6K, mTOR, JNK, and c-Jun. LY294002, a PI3K inhibitor, inhibited HPV-16 oncoprotein-induced activation of Akt, P70S6K, and P85S6K, expression of HIF-1α, VEGF, and IL-8, and in vitro angiogenesis. c-Jun knockdown by specific siRNA abolished HPV-16 oncoprotein-induced HIF-1α, VEGF, and IL-8 expression and in vitro angiogenesis. Additionally, HPV-16 oncoproteins promoted HIF-1α protein stability via blocking proteasome degradation pathway, but c-Jun knockdown abrogated this effect. Furthermore, HPV-16 oncoproteins increased the quantity of c-Jun binding to HIF-1α. PI3K/Akt signaling pathway and c-Jun are involved in HPV-16 oncoprotein-induced HIF-1α, VEGF, and IL-8 expression and in vitro angiogenesis. Moreover, HPV-16 oncoproteins promoted HIF-1α protein stability possibly through enhancing the interaction between c-Jun and HIF-1α, thus making a contribution to angiogenesis in NSCLC cells.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: 1-Phosphatidylinositol 3-kinase / Activation / AKT protein / Angiogenesis / Biology and Life Sciences / c-Jun protein / Cancer / Carcinoma, Non-Small-Cell Lung - blood supply / Carcinoma, Non-Small-Cell Lung - metabolism / Carcinoma, Non-Small-Cell Lung - virology / Cell Line, Tumor / Chromones - pharmacology / Endothelial cells / Enzyme-linked immunosorbent assay / Genes, jun - drug effects / Human papillomavirus / Humans / Hypoxia / Hypoxia-Inducible Factor 1, alpha Subunit / Hypoxia-inducible factors / Immunoprecipitation / In Vitro Techniques / Interleukin 8 / Interleukin-8 - metabolism / Kinases / Laboratories / Lung cancer / Lung diseases / Lung Neoplasms - blood supply / Lung Neoplasms - metabolism / Lung Neoplasms - virology / MAP Kinase Signaling System - drug effects / Medicine and Health Sciences / Morpholines - pharmacology / mRNA / Neovascularization, Pathologic - metabolism / Neovascularization, Pathologic - virology / Non-small cell lung carcinoma / Oncogene Proteins, Viral - genetics / Oncogene Proteins, Viral - metabolism / Oncoproteins / Papillomavirus E7 Proteins - genetics / Papillomavirus E7 Proteins - metabolism / Plasmids / Proteasomes / Proteins / Repressor Proteins - genetics / Repressor Proteins - metabolism / Signal transduction / Signaling / siRNA / Smoking / Stability / TOR protein / Transcription factors / Umbilical vein / Vascular endothelial growth factor / Vascular Endothelial Growth Factor A / Western blotting