Abstract 37: Alterations in the metabolism of highly motile cells: Implications for cancer metastasis
Authors: Van Wassenhove Lauren D. , Jaffe Erica R. , Wynn Michelle L. , Merajver Sofia D. 
Published: February 2011

Abstract
It has been known for some time that cancer cells have aberrant metabolism. Our lab observed that highly proliferative cells are not very motile, and likewise, highly motile cells do not proliferate rapidly. Thus, we hypothesized that cells direct their metabolism toward rapidly dividing or toward moving, but not both processes. This may be important in the progression of cancer from primary tumor to end-stage metastasis. By understanding how the metabolism and signaling pathways change in these very different situations, it may be possible to discover new drug targets to prevent cancers from progressing.
Traditionally, studies of cellular metabolism and proliferation have been measured in fixed cells. In order to truly understand a living system, quantitative measurements in live cells are necessary. To this end, we utilized the Fluorescent Ubiquitination-based Cell Cycle Indicator or FUCCI, developed by Sakaue-Sawano et al. This system involves two vectors, one of which encodes Geminin fused to a green fluorescent probe, and the other which encodes Cdt1 fused to a red fluorescent probe. The levels of these proteins are regulated inversely during the cell cycle, with Geminin at its highest level during S, G2, and M phase, while Cdt1 is highest during G1. Therefore, when our stable transfectants are dividing (in S, G2, or M phases), their nuclei fluoresce green, while in the G1 phase of the cell cycle, their nuclei fluoresce red.
Utilizing this system in our aggressive breast cancer cell lines enabled us to measure proliferation and metabolism in live cells. This also allowed us to directly test our hypothesis that actively motile cells are not proliferating (red), and proliferating cells (green) are not actively motile. By treating with different anti-proliferative and metabolic agents, we measured what percentage of cells cease dividing, and what percentage continued to grow. We used flow cytometry to separate these different populations and to determine genetic differences that may make them more or less resistant to these drugs.
We also examined known genes involved in both metabolism and motility. To do this, we measured protein and mRNA expression of several proteins in the glycolysis, lipid metabolism, and cholesterol synthesis pathways, as well as the small motility-related GTPases. From our findings, a preliminary model of the interaction between metabolism and metastasis is emerging. The proteins likely involved in metastasis are small GTPases. These proteins are modified by prenylation, allowing them to localize to the cell membrane and direct motility. Our results suggest that MDA-MB-231 cells may have a slower rate of glycolysis, but display increased cholesterol synthesis to prenylate proteins, while SUM 149 cells have an increased rate of glycolysis. This may help explain the differences in the phenotypes of these cancers, and may allow for the prediction of future drug targets to prevent cancer metastasis.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 37.