Effect of physicochemical parameters on the L-methioninase activity of Methylobacterium sp. and its in vitro anticancer activity in combination with tamoxifen citrate

Abstract

BackgroundMethionine dependence is a metabolic abnormality observed exclusively in cancer cells. Methionine depletion using methioninase is therefore an attractive strategy for cancer treatment. The current study focuses on the purification of L-Methioninase from a bacterial isolate, Methylobacterium sp. JUBTK33, for its anticancer application in conjunction with Tamoxifen in MCF-7, HepG2, and HeLa cancer cell lines.ResultsL-methioninase was purified from Methylobacterium sp. JUBTK33 using a DEAE-Sephadex G-200 column, resulting in a 6.15-fold purification with a specific activity of 17.89 U/mg. At 40 °C and pH 8.5, the enzymatic biochemical characteristics demonstrated increased enzyme activity. Na+ ions (1 mM) significantly enhanced the enzyme’s activity, while Li+, Mn++, Ni++, Fe++, and K+ had little impact. The highest activity was observed at a 225 µM (2.5%) substrate concentration of methionine, with Vmax and Km values of 0.48 U/mL/min and 48.23 µM, respectively. The enzyme’s potential anticancer effect in combination with TAM was evaluated on HepG2, MCF-7, and HeLa cell lines. It was found to be highly effective on MCF-7 cell lines, with a combination of L-MET-TAM (5 and 10 µg/mL) resulting in 3.72% and 1.0% cell viabilities, and IC50 values of 9.701 µg/mL and 5.72 µg/mL, respectively. On the normal HEK-293 cell line, the combination of L-MET-TAM (10 µg/mL) demonstrated approximately an 18% protective effect compared to TAM alone.ConclusionThe combination approach demonstrated remarkable success against cancer cells in vitro, highlighting the need for further investigations to develop it into an effective treatment strategy.