Abstract 1088: HOXB13 inhibition of succinate dehydrogenase leads to epithelial-to-mesenchymal transition in mouse ovarian cancer cell lines.

HOXB13 is a homeobox gene whose dysregulation has been implicated in cancer. We have previously shown that HOXB13 plays an oncogenic role in ovarian cancer by driving epithelial-to-mesenchymal transition (EMT); however the mechanism by which this occurs has not been established. Global metabolomics profiling revealed that overexpression of HOXB13 in genetically defined mouse ovarian cancer cell lines inhibits succinate dehydrogenase (SDH) activity. Targeted-knockdown of the SDH subunit SdhB by shRNA results in mislocalization of E-cadherin and a spindle-shaped morphology suggestive of EMT. Metabolomics and real-time flux analysis showed that knockdown of SdhB results in elevated levels of succinate as well as defective mitochondrial respiration. Despite the mitochondrial respiration defect, SdhB knockdown cells display increased anchorage-independent growth in soft agar and enhanced xenograft tumor formation. Elevated levels of succinate have been shown to inhibit α-ketoglutarate requiring enzymes such as the Jumanji C (JmjC)-domain containing H3K27 demethylases, UTX and JMJD3. Indeed, knockdown of SdhB results in a hypermethylated epigenome as evidenced by increased levels of H3K27me2 and H3K27me3. Both the epigenetic and EMT phenotypes can be recapitulated by pharmacological inhibition of UTX and JMJD3 in control cells. These data point to a mechanism wherein modulation of oncometabolite levels can affect the epigenome, thereby influencing cancer cell morphology and tumorigenic properties. Citation Format: Paul-Joseph Aspuria, Dong-Joo Cheon, Maricel Gozo, Brenda Salumbides, Laurent Vergnes, John Asara, Karen Reue, Elizabeth Kensicki, Beth Karlan, Sandra Orsulic. HOXB13 inhibition of succinate dehydrogenase leads to epithelial-to-mesenchymal transition in mouse ovarian cancer cell lines. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1088. doi:10.1158/1538-7445.AM2013-1088