Suppression of anaplerotic enzyme pyruvate carboxylase expression inhibits proliferation and invasion of breast cancer cell line MDA-MB-231

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 292-302-Breast & Prostate Cancer
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-299
Phatchariya Phannasil* and Sarawut Jitrapakdee
Mahidol University, Bangkok, Thailand
Tumor cells require macromolecular precursors to satisfy their requirements for growth and proliferation. Interruption of this supply has been proposed as a therapeutic strategy in cancer. Most tumor cells require Krebs cycle intermediates as precursors for the biosynthesis of lipids, nucleic acids and proteins (1). Anaplerosis (refilling the pool of precursor molecules) in this pathway is crucial for maintaining cell growth. Previous studies have shown that anaplerosis via pyruvate carboxylase (PC) dependent pyruvate carboxylation is increased in lung cancer (1) and glioblastoma (2). The high rate of pyruvate carboxylation was proposed to support anaplerosis required during the transition from normal to malignant growth. To examine whether PC is over-expressed in other types of cancer and if there is a correlation to the degree of metastasis, we investigated the expression of PC in breast cancer cell lines that possess different metastatic potentials, i.e. MCF-7 (low metastasis) and MDA-MB-231 (high metastasis) cell lines. Quantitative real time PCR and Western blotting clearly demonstrates that the MDA-MB-231 cell line express 5-fold higher PC than the MCF-7 cell line. To examine whether over-expression of PC in both MCF-7 and MDA-MB-231 cell lines contributes to the high rate of proliferation and metastatic potential, PC expression was suppressed by siRNA. Reducing PC expression by 90% in MDA-MB-231 cells reduces their viability and proliferation by 30-40% and inhibits invasion through Matrigel by 40%, suggesting that pyruvate carboxylation via PC is required for both proliferation and metastasis of breast cancer. RT-PCR analysis of cDNAs prepared from both MCF-7 and MDA-MB-231 cells shows that the gluconeogenic/lipogenic (P1) promoter of the PC gene is switched on in both cell lines, indicating the selective activation of this promoter in breast cancer.

(1) Tzuling Cheng, et al. (2011) Pyruvate carboxylase is required for glutamine-independent growth of tumor cells. PNAS 8674–8679. (2) Teresa WM Fan, et al. (2009) Altered regulation of metabolic pathways in human lung cancer discerned by 13C stable isotope-resolved metabolomics (SIRM). Molecular Cancer  8:41 doi:10.1186/1476-4598-8-41

Nothing to Disclose: PP, SJ

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Sources of Research Support: RGJ-Ph.D., Thailand Research Fund