Hypoxia up-regulates SERPINB3 through HIF-2α in human liver cancer cells

• Published in: Oncotarget 2015-02, Vol.6 (4), p.2206-2221
• Main Authors: Cannito, Stefania, Turato, Cristian, Paternostro, Claudia, Biasiolo, Alessandra, Colombatto, Sebastiano, Cambieri, Irene, Quarta, Santina, Novo, Erica, Morello, Elisabetta, Villano, Gianmarco, Fasolato, Silvano, Musso, Tiziana, David, Ezio, Tusa, Ignazia, Rovida, Elisabetta, Autelli, Riccardo, Smedile, Antonina, Cillo, Umberto, Pontisso, Patrizia, Parola, Maurizio
• Format: Article
• Language: English
• Subjects: Antigens, Neoplasm - genetics; Antigens, Neoplasm - metabolism; Base Sequence; Basic Helix-Loop-Helix Transcription Factors - genetics; Basic Helix-Loop-Helix Transcription Factors - metabolism; Blotting, Western; Carcinoma, Hepatocellular - genetics; Carcinoma, Hepatocellular - metabolism; Carcinoma, Hepatocellular - pathology; Cell Hypoxia; Cell Line, Tumor; Gene Expression Regulation, Neoplastic; Hep G2 Cells; HT29 Cells; Humans; Immunohistochemistry; Liver Neoplasms - genetics; Liver Neoplasms - metabolism; Liver Neoplasms - pathology; Molecular Sequence Data; Promoter Regions, Genetic - genetics; Protein Binding; Reactive Oxygen Species - metabolism; Research Paper; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Serpins - genetics; Serpins - metabolism; Up-Regulation
• ISSN: 1949-2553; 1949-2553
• DOI: 10.18632/oncotarget.2943

SERPINB3 is a cysteine-proteases inhibitor up-regulated in a significant number of cirrhotic patients carrying hepatocellular carcinoma (HCC) and recently proposed as a prognostic marker for HCC early recurrence. SERPINB3 has been reported to stimulate proliferation, inhibit apoptosis and, similar to what reported for hypoxia, to trigger epithelial-to-mesenchymal transition (EMT) and increased invasiveness in liver cancer cells. This study has investigated whether SERPINB3 expression is regulated by hypoxia-related mechanisms in liver cancer cells. Exposure of HepG2 and Huh7 cells to hypoxia up-regulated SERPINB3 transcription, protein synthesis and release in the extracellular medium. Hypoxia-dependent SERPINB3 up-regulation was selective (no change detected for SERPINB4) and operated through hypoxia inducible factor (HIF)-2α (not HIF-1α) binding to SERPINB3 promoter, as confirmed by chromatin immuno-precipitation assay and silencing experiments employing specific siRNAs. HIF-2α-mediated SERPINB3 up-regulation under hypoxic conditions required intracellular generation of ROS. Immuno-histochemistry (IHC) and transcript analysis, performed in human HCC specimens, revealed co-localization of the two proteins in liver cancer cells and the existence of a positive correlation between HIF-2α and SERPINB3 transcript levels, respectively. Hypoxia, through HIF-2α-dependent and redox-sensitive mechanisms, up-regulates the transcription, synthesis and release of SERPINB3, a molecule with a high oncogenic potential.