PI3K/Akt/HIF-1α signaling pathway mediates HPV-16 oncoprotein-induced expression of EMT-related transcription factors in non-small cell lung cancer cells

Jinhua Liu; Bingyu Huang; Zihan Xiu; Zhiyuan Zhou; Jiao Liu; Xiangyong Li; Xudong Tang

doi:10.7150/jca.26112

PI3K/Akt/HIF-1α signaling pathway mediates HPV-16 oncoprotein-induced expression of EMT-related transcription factors in non-small cell lung cancer cells

J Cancer. 2018 Sep 8;9(19):3456-3466. doi: 10.7150/jca.26112. eCollection 2018.

Authors

Jinhua Liu¹, Bingyu Huang¹, Zihan Xiu¹, Zhiyuan Zhou¹, Jiao Liu¹, Xiangyong Li^{1

2

3}, Xudong Tang^{1

2

3

4}

Affiliations

¹ Institute of Biochemistry and Molecular Biology, Guangdong Medical University, Zhanjiang 524023, P.R. China.
² Collaborative innovation center for antitumor active substance research and development, Guangdong Medical University, Zhanjiang 524023, P.R. China.
³ Dongguan Key Laboratory of Medical Bioactive Molecular Developmental and Translational Research, Guangdong Medical University, Dongguan 523808, P.R. China.
⁴ Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Guangdong Medical University, Dongguan 523808, P.R. China.

Abstract

Background: Our previous studies have demonstrated that human papillomaviruse (HPV)-16 oncoproteins promoted epithelial-mesenchymal transition (EMT), leading to non-small cell lung cancer (NSCLC) progression, but the underlying molecular mechanisms still remain unclear. PI3K/Akt/HIF-1α signaling pathway has been reported to mediate hypoxia-induced EMT. In this study, we further explored the role of PI3K/Akt/HIF-1α signaling pathway in HPV-16 oncoprotein-induced EMT in NSCLC cells. Methods: A549 and NCI-H460 NSCLC cells were transiently transfected with pEGFP-HPV-16 E6 or E7 constructs. Western blotting and RT-qPCR were respectively performed to determine the protein and mRNA expression of EMT-related transcription factors. HPV-16 E6 or E7-transfected NSCLC cells were co-transfected with specific HIF-1α-siRNA or pretreated with different concentrations of LY294002, a specific PI3K inhibitor, followed by the analysis of expression of EMT-related transcription factors. The correlation between HIF-1α and EMT-related transcription factors in NSCLC tissues was analyzed by immunohistochemical staining and Spearman rank correlation coefficient. Results: HPV-16 E6 and E7 oncoproteins upregulated the expression of Slug and Twist1, the EMT-related transcription factors, at both protein and mRNA levels in A549 and NCI-H460 cells. The co-transfection with specific HIF-1α-siRNA, but not the non-specific (NS)-siRNA, significantly abrogated HPV-16 oncoprotein-induced upregulation of ZEB1, Snail1, Slug, and Twist1 at both protein and mRNA levels. Additionally, pretreatment with LY294002 obviously blocked HPV-16 E6- and E7-induced Snail1, Slug, and Twist1 protein expression in A549 and NCI-H460 cells. Further analysis of clinical specimens showed that HIF-1α protein was strongly expressed in NSCLC tissues, which was positively correlated with ZEB1, Snail1, Slug, and Twist1 protein expression. Conclusions: PI3K/Akt/HIF-1α may contribute to the progression of HPV-associated NSCLC via mediating the expression of EMT-related transcription factors in NSCLC cells.

Keywords: PI3K/Akt/HIF-1α; epithelial-mesenchymal transition (EMT); human papillomaviruse (HPV)-16; non-small cell lung cancer (NSCLC); transcription factor.