BH4 domain of bcl-2 protein is required for its proangiogenic function under hypoxic condition

Chiara Gabellini, Teresa De Luca, Daniela Trisciuoglio, Marianna Desideri, Marta Di Martile, Daniela Passeri, Antonio Candiloro, Mauro Biffoni, Maria Giulia Rizzo, Augusto Orlandi, Donatella Del Bufalo

Research output: Contribution to journalArticlepeer-review

Abstract

Beyond its classical role as apoptosis inhibitor, bcl-2 protein promotes tumor angiogenesis and the removal of N-terminal bcl-2 homology (BH4) domain abrogates bcl-2-induced hypoxia-inducible factor 1 (HIF-1)-mediated vascular endothelial growth factor (VEGF) expression in hypoxic cancer cells. Using M14 human melanoma cell line and its derivative clones stably overexpressing bcl-2 wild-type or deleted of its BH4 domain, we found that conditioned media (CM) from cells expressing BH4-deleted bcl-2 protein showed a reduced capability to increase in vitro human endothelial cells proliferation and differentiation, and in vivo neovascularization compared with CM from cells overexpressing wild-type bcl-2. Moreover, xenografts derived from cells expressing bcl-2 lacking BH4 domain showed a reduction of metastatic potential compared with tumors derived from wild-type bcl-2 transfectants injection. Stably expressing the Flag-tagged N-terminal sequence of bcl-2 protein, encompassing BH4 domain, we found that this domain is sufficient to enhance the proangiogenic HIF-1/VEGF axis under hypoxic condition. Indeed, lacking of BH4 domain abolishes the interaction between bcl-2 and HIF-1α proteins and the capability of exogenous bcl-2 protein to localize in the nucleus. Moreover, when endoplasmic reticulumtargeted bcl-2 protein is overexpressed in cells, this protein lost the capability to synergize with hypoxia to induce the proangiogenic HIF-1/VEGF axis as shown by wild-type bcl-2 protein. These results demonstrate that BH4 domain of bcl-2 is required for the ability of this protein to increase tumor angiogenesis and progression and indicate that bcl-2 nuclear localization may be required for bcl-2-mediated induction of HIF-1/VEGF axis.

Original languageEnglish
Pages (from-to)2558-2567
Number of pages10
JournalCarcinogenesis
Volume34
Issue number11
DOIs
Publication statusPublished - Nov 2013

ASJC Scopus subject areas

  • Cancer Research

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