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The Leucine Metabolic Pathway is Differentially Regulated by c‐MYC and NFAT in T cells and Their Cancerous Counterpart EL‐4 lymphoma cells
Author(s) -
Brenner Michelle,
Torres Ashley,
Hutson Susan,
Ananieva Elitsa
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.964.4
Subject(s) - nfat , cancer cell , transcription factor , biology , t cell , enzyme , gene , biochemistry , chemistry , microbiology and biotechnology , immune system , cancer , genetics
Tumor cells can escape immune surveillance by competing with T cells for common metabolites and redirecting nutrients for their own advantage. Leucine is a nutrient that stimulates protein biosynthesis, while the degradation of leucine provides energy and metabolites for the TCA cycle. The first two enzymatic steps in leucine degradation are catalyzed by the branched‐chain aminotransferase (cytosolic BCATc and mitochondrial BCATm, step 1) and the branched‐chain α‐ketoacid dehydrogenase complex (BCKDC) that is composed of three enzymes, E1, E2, and E3 (step 2). The gene regulation of these enzymes is largely unknown but important to understand how T cells and cancer cells interact on metabolic level in the tumor microenvironment. The objective of this research was to compare the gene regulation of BCATc, BCATm, the E1α subunit of E1, and E2 in T cells and their cancerous counterpart, EL‐4 lymphoma cells, and better understand the function of the leucine metabolic pathway in these cells. Bioinformatic analysis revealed that the transcription factors c‐Myc and NFAT (nuclear factor of activated T cells) have binding sites at the promoter regions of the genes encoding for BCATm, BCATc, E1α, and E2. We consequently treated activated T cells and EL‐4 lymphoma cells with 1μM cyclosporine A (CsA) and 100μM 10058‐F4, which inhibit NFAT and c‐Myc, respectively. Next, we explored the impact of CsA and NFAT treatments on the mRNA and protein expression of the BCAT and BCKDC enzymes and found that 10058‐F4 inhibited all genes in both activated T cells and EL‐4 cells. These results suggest that T cells and EL‐4 lymphoma cells use c‐Myc to up‐regulate the leucine metabolic pathway upon T cell activation and/or EL‐4 lymphoma growth. CsA, on the other hand, inhibited the protein expression of BCATc and E2 in T cells only implying that NFAT pathway activates the first two steps in leucine degradation in activated T cells but not in EL‐4 lymphoma cells. This research will aid in exploring possibilities to modulate the leucine metabolic pathway in a direction that provides an advantage to T cells to better combat cancer cells in the tumor microenvironment. Support or Funding Information IOER startup, Des Moines University (Ananieva, EA)