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

• Published in: PloS one 2014-07, Vol.9 (7), p.e103440
• Main Authors: Zhang, Erying, Feng, Xiaowei, Liu, Fei, Zhang, Peihua, Liang, Jie, Tang, Xudong
• Format: Article
• Language: English
• Subjects: 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
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0103440

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.