Methionine γ-Lyase 2-AminoButyrate Deaminase (MEGL-2ABD) as a Gene Therapeutic Agent for Cancers

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Methionine is a key nutrient that is required for many metabolic processes/pathways. In bacteria methionine is cleaved into methanethiol and 2-aminobutyrate which is deaminated into α-ketobutyrate and ammonia by methionine γ-lyase 2-aminobutyrate deaminase (MEGL-2ABD); an enzyme that is absent in mammals. We have molecularly cloned Porphyromonas gingivalis, DNA (FJ875028) of MEGL-2ABD gene into pEGFP-C3 mammalian expression vector and have transfected the construct into various cancer cell lines such as Hela, HEK-AD293T, BHK-21, methionine dependent prostate PC-3, and independent DU-145 cancer cell lines. Confocal microscopy evinced two interesting observations that occur under methionine deprivation due to MEGL-2ABD. 1. Severe cell aggregation and 2.Cell death perhaps due to apoptotic signaling. Both of these processes are reversed by propargylglycine, an inhibitor of MEGL-2ABD. The severity of cell aggregation or cell death varied depending on the cell types. When MEGL-2ABD gene therapeutic agent was compared to existing anticancer drugs such as methotrexate, MEGL2ABD had about equal cell death measured by MTT assay. Combination of MEGL-2ABD, along with methotrexate, AraC and vesicular stomatitis virus (VSV) had much higher cell death in prostate cancer PC3 and DU145 cell lines. Exogenously, MEGL-2ABD treated culture media had same effects to that of transfected cells. Thus, cytoplasmic localization of MEGL-2ABD has great potential as a gene therapeutic agent to control cancer cell division.