Abstract 1203: Metastasis-associated oncogene RhoC as a regulator of glutamine metabolism in the inflammatory breast cancer cell line SUM149

Metabolic reprogramming is increasingly recognized as a fundamental hallmark of cancer. While the Warburg effect and normal proliferative metabolism are similar, they are not equivalent. We hypothesize that there are key drivers of malignant metabolism that can be modulated to impede cancer proliferation without substantial effects on normal tissue growth. Using 13C-labeled glucose and glutamine tracers in combination with mass spectrometry and measurements of extracellular glucose, lactate, and glutamine flux, we have characterized system level differences in a series of breast cancer cell lines as well as normal-like breast epithelial cells. We observed an increase in the reductive carboxylation of glutamine-derived citrate and alpha-ketoglutarate in the triple-negative inflammatory breast cancer cell line SUM149. We also observed that the SUM149 exhibit high levels of HIF-1α and low levels of oxygen consumption under normoxia, suggesting that the cell line is highly adapted to hypoxia. Surprisingly, the stable depletion of HIF-1α via shRNA had no significant effect on the metabolic profile of these cells. Previous work by our lab and others has demonstrated that the GTPase RhoC is a driver of the metastatic phenotype exhibited by inflammatory breast cancer. Activation of RhoC is known to induce cytoskeletal rearrangements and increase invasive potential. The Rho GTPase family of proteins has also recently been linked to metabolism, specifically regulation of glutaminase activity. Here we show that stable knockdown of RhoC in SUM149 cells results in a marked decrease in the rate of both glutamine uptake and intracellular reductive carboxylation. This work reinforces the role of RhoC as an important driver of inflammatory breast cancer metastatic potential. We conclude that RhoC remains an important clinical target with the potential to alter patient outcomes. Citation Format: Joel A. Yates, Michelle L. Wynn, ZhiFen Wu, Charles R. Evans, Charles Burant, Santiago D. Schnell, Sofia D. Merajver. Metastasis-associated oncogene RhoC as a regulator of glutamine metabolism in the inflammatory breast cancer cell line SUM149. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1203. doi:10.1158/1538-7445.AM2015-1203