Opposite prognostic roles of HIF1α and HIF2α expressions in bone metastatic clear cell renal cell cancer
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Attila Szendrői1,*, A. Marcell Szász2,*, Magdolna Kardos2,*, Anna-Mária Tőkés2,3, Roni Idan2, Miklós Szűcs1, Janina Kulka2, Péter Nyirády1, Miklós Szendrői4, Zoltán Szállási5,6, Balázs Győrffy7,8, József Tímár2,3,*
1Department of Urology, Semmelweis University, Budapest 1082, Hungary
22nd Department of Pathology, Semmelweis University, Budapest 1091, Hungary
3Molecular Oncology Research Group, Hungarian Academy of Sciences and Semmelweis University, Budapest 1091, Hungary
4Department of Orthopedics, Semmelweis University, Budapest 1113, Hungary
5Children's Hospital Informatics Program at the Harvard-MIT Division of Health Sciences and Technology, Harvard Medical School, Boston, MA 02115, USA
6Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Lyngby 2800, Denmark
7MTA-TTK Lendület Cancer Biomarker Research Group, Budapest 1117, Hungary
82nd Department of Pediatrics, Semmelweis University, Budapest 1082, Hungary
*These authors have contributed equally to this work
József Tímár, email: email@example.com
Keywords: renal cell cancer, prognosis, bone metastasis, hypoxia inducible factor
Received: August 20, 2015 Accepted: April 10, 2016 Published: May 27, 2016
BACKGROUND: Prognostic markers of bone metastatic clear cell renal cell cancer (ccRCC) are poorly established. We tested prognostic value of HIF1α/HIF2α and their selected target genes in primary tumors and corresponding bone metastases.
RESULTS: Expression of HIF2α was lower in mRCC both at mRNA and protein levels (p/mRNA/=0.011, p/protein/=0.001) while HIF1α was similar to nmRCC. At the protein level, CAIX, GAPDH and GLUT1 were increased in mRCC. In all primary RCCs, low HIF2α and high HIF1α as well as CAIX, GAPDH and GLUT1 expressions correlated with adverse prognosis, while VEGFR2 and EPOR gene expressions were associated with favorable prognosis. Multivariate analysis confirmed high HIF2α protein expression as an independent risk factor. Prognostic validation of HIFs, LDH, EPOR and VEGFR2 in RNA-Seq data confirmed higher HIF1α gene expression in primary RCC as an adverse (p=0.07), whereas higher HIF2α and VEGFR2 expressions as favorable prognostic factors. HIF1α/HIF2α-index (HIF-index) proved to be an independent prognostic factor in both the discovery and the TCGA cohort.
PATIENTS AND METHODS: Expressions of HIF1α and HIF2α as well as their 7 target genes were analysed on the mRNA and protein level in 59 non-metastatic ccRCCs (nmRCC), 40 bone metastatic primary ccRCCs (mRCC) and 55 corresponding bone metastases. Results were validated in 399 ccRCCs from the TCGA project.
CONCLUSIONS: We identified HIF2α protein as an independent marker of the metastatic potential of ccRCC, however, unlike HIF1α, increased HIF2α expression is a favorable prognostic factor. The HIF-index incorporated these two markers into a strong prognostic biomarker of ccRCC.
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