Abstract 5260: Different cell metabolism by FAP-α overexpression in triple negative breast cancer cells
Authors: Mori Noriko , Krishnamachary Balaji , Jin Jiefu , Barnett James , Mironchik Yelena , Bhujwalla Zaver M. 
Published: August 2019

Fibroblast activation protein-α (FAP-α) is a cell surface serine protease that is attracting increasing interest because of its role in immune suppression and cancer metastasis. To understand the role of FAP-α in cancer cell metabolism we engineered triple negative MDA-MB-231 cells to stably overexpress FAP-α and compared metabolic profiles of parental and FAP-α overexpressing cells using 1H MR spectroscopy. We observed a significant increase of aspartate, glycerophosphocholine, lactate, myoinositol and phosphatidylcholine with FAP-α overexpression. These results identify a previously unknown role of FAP-α in modifying cancer cell metabolism that may provide new insights in its functional roles in cancer progression.

MDA-231luc (parent cells), derived from MDA-MB-231, were purchased from Sibtech Inc. MDA-231luc-FAPα (231-FAPα) cells were engineered using the gene for human FAP that was subcloned into lentiviral vector pMA3211. Immunoblot analysis with FAP-α antibody confirmed the overexpression of FAP-α protein in 231-FAPα cells. Approximately 3.5x107 cells were used for dual-phase cell extraction as previously described [1]. 1H MR spectra were recorded on a Bruker Biospin Avance-III 750 MHz NMR spectrometer and analyzed using TOPSPIN 3.5 software. Integrals of the metabolites of interest were determined and normalized to the number of cells and internal standard. Metabolite levels were quantified as arbitrary units (A.U.) from three experimental samples from each cell line. Statistical significance was evaluated using the unpaired one tailed Student t test.

We identified 18 metabolites from the aqueous phase (8 amino acids, 3 choline metabolites and 7 others) and 10 signals from the lipid phase (7 Fatty acids (FA), Cholesterol, Phosphatidylethanolamine (PtdE), -N(CH3)3: Phosphatidylcholine (PtdCho) & Sphingomyelin (SM)) using 1H MR spectra. We found that 4 metabolites (aspartate, glycerophosphocholine (GPC), lactate and myo-inositol) from the aqueous phase and 2 signals (FA: -CH2-CH2-CH=, and -N(CH3)3) from the lipid phase were significantly higher in 231-FAPα cells. It is likely that PtdCho level was significantly higher in 231-FAPα cells since the majority of -N(CH3)3 signals are from PtdCho. All the FA signals tended to be higher in 231-FAPα cells compared to parental cells. Since the average cell numbers at the time of cell collection were similar, cell density differences did not contribute to differences in metabolite levels. We are currently investigating the molecular mechanisms underlying these differences. The significant differences in water-soluble and lipid-soluble extracts provide new insights into the metabolic modulatory role of FAP-α.

[1] Krishnamachary B, et al. Cancer Res. 2009;15;69(8):3464-71

This work was supported by NIH R35CA209960.

Citation Format: Noriko Mori, Balaji Krishnamachary, Jiefu Jin, James Barnett, Yelena Mironchik, Zaver M. Bhujwalla. Different cell metabolism by FAP-α overexpression in triple negative breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5260.